CiteULike: gigiluk00's library [100 articles]

Training of executive functions in Parkinson's disease.

G Sammer — 2008-03-30T02:22:20-00:00

J Neurol Sci, Vol. 248, No. 1-2. (25 October 2006), pp. 115-119.

Cognitive disturbances are common in Parkinson's disease (PD). Examination of cognitive function often reveals deficits in executive functions, including maintenance and inhibition of attention, flexibility in thinking, and planning. The involvement of the dopaminergic system in cognitive executive functions has been suggested by numerous studies. The aim of the present study was to analyze the effect of cognitive training on cognitive performance of PD-patients (N=26). Half of the patients participated in a cognitive training regimen, while the other patients only received standard treatment. The outcome showed improved performance of the group with cognitive treatment in two executive tasks after the training period, while no improvement was seen in the standard-treatment group. The results indicate that specific training is required for improvement of executive functions, while general rehabilitation is not sufficient. Thus, PD-patients might benefit from a short-term cognitive executive function training program that is tailored to the individual patient's needs.

The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials

Sonja Kotz — 2008-03-27T23:38:10-00:00

Journal of Neurolinguistics, Vol. 17, No. 2-3. (March 2004), pp. 215-235.

Event-related brain potentials (ERP) studies show that L2 learners can exhibit relatively native-like processing patterns in semantics [Bilingual.: Lang. Cogn. 4 (2001) 123], but examining different semantic information types--associative and categorical--shows that L2 semantic processing is sensitive to proficiency. If the links between concepts and L2 words are weak for L2 learners [J. Memory Lang. 33 (1994) 149; Memory Cogn. 23 (1995) 166], then lower proficiency learners are less likely to show native-like RT and ERP N400 priming effects for categorical pairs (boy-junior) than are more advanced learners. If proficiency modulates the automaticity of processing in the L2 lexical network, less proficient late learners may also differ from advanced learners in associative priming (boy-girl). We report proficiency effects with ERP and RT data from word list priming performed by advanced and less proficient late German learners of English. The advanced learners showed associative RT and N400 ERP priming effects similar to early advanced learners and native speakers [Bilingual.: Lang. Cogn. 4 (2001) 143], but very limited categorical priming effects. The lower proficiency group showed no RT effects for either categorical or associative pairs but associative N400 priming. Results suggest that in a fast word list priming task, proficiency and the type of semantic information processed are important determinants of how autonomous L2 semantic processing can be.

Does bilingualism hamper lexical access in speech production

Iva Ivanova — 2008-01-25T01:38:38-00:00

Acta Psychologica, Vol. 127, No. 2. (February 2008), pp. 277-288.

In the present study, we tested the hypothesis that bilingualism may cause a linguistic disadvantage in lexical access even for bilinguals' first and dominant language. To this purpose, we conducted a picture naming experiment comparing the performance of monolinguals and highly-proficient, L1-dominant bilinguals. The results revealed that monolinguals name pictures faster than bilinguals, both when bilinguals perform picture naming in their first and dominant language and when they do so in their weaker second language. This is the first time it has been demonstrated that bilinguals show a naming disadvantage in their L1 in comparison to monolingual speakers.

The bilingual brain. Proficiency and age of acquisition of the second language.

D Perani — 2006-04-30T08:54:30-00:00

Brain, Vol. 121 ( Pt 10) (October 1998), pp. 1841-1852.

Functional imaging methods show differences in the pattern of cerebral activation associated with the subject's native language (L1) compared with a second language (L2). In a recent PET investigation on bilingualism we showed that auditory processing of stories in L1 (Italian) engages the temporal lobes and temporoparietal cortex more extensively than L2 (English). However, in that study the Italian subjects learned L2 late and attained a fair, but not an excellent command of this language (low proficiency, late acquisition bilinguals). Thus, the different patterns of activation could be ascribed either to age of acquisition or to proficiency level. In the current study we use a similar paradigm to evaluate the effect of early and late acquisition of L2 in highly proficient bilinguals. We studied a group of Italian-English bilinguals who acquired L2 after the age of 10 years (high proficiency, late acquisition bilinguals) and a group of Spanish-Catalan bilinguals who acquired L2 before the age of 4 years (high proficiency, early acquisition bilinguals). The differing cortical responses we had observed when low proficiency volunteers listened to stories in L1 and L2 were not found in either of the high proficiency groups in this study. Several brain areas, similar to those observed for L1 in low proficiency bilinguals, were activated by L2. These findings suggest that, at least for pairs of L1 and L2 languages that are fairly close, attained proficiency is more important than age of acquisition as a determinant of the cortical representation of L2.

Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgments. Blood oxygen level dependent.

MW Chee — 2008-03-27T23:33:15-00:00

Neuroimage, Vol. 13, No. 6 Pt 1. (June 2001), pp. 1155-1163.

The effect of relative language proficiency on the spatial distribution and magnitude of BOLD signal change was evaluated by studying two groups of right-handed English-Mandarin bilingual participants with contrasting language proficiencies as they made semantic judgments with words and characters. Greater language proficiency corresponded to shorter response times and greater accuracy in the semantic judgment task. Within the left prefrontal and parietal regions, the change in BOLD signal was smaller in a participant's more proficient language. The least proficient performance was associated with right, in addition to left, inferior frontal activation. The results highlight the importance of taking into consideration nature of task and relative language proficiency when drawing inferences from functional imaging studies of bilinguals.

Critical evidence: a test of the critical-period hypothesis for second-language acquisition.

K Hakuta — 2005-07-26T17:26:14-00:00

Psychol Sci, Vol. 14, No. 1. (January 2003), pp. 31-38.

The critical-period hypothesis for second-language acquisition was tested on data from the 1990 U.S. Census using responses from 2.3 million immigrants with Spanish or Chinese language backgrounds. The analyses tested a key prediction of the hypothesis, namely, that the line regressing second-language attainment on age of immigration would be markedly different on either side of the critical-age point. Predictions tested were that there would be a difference in slope, a difference in the mean while controlling for slope, or both. The results showed large linear effects for level of education and for age of immigration, but a negligible amount of additional variance was accounted for when the parameters for difference in slope and difference in means were estimated. Thus, the pattern of decline in second-language acquisition failed to produce the discontinuity that is an essential hallmark of a critical period.

Effect of Language Switching on Arithmetic: A Bilingual fMRI Study

Vinod Venkatraman — 2006-01-06T18:42:36-00:00

Journal of Cognitive Neuroscience, Vol. 18, No. 1. (January 2006), pp. 64-74.

Effects of syntactic complexity in L1 and L2; An fMRI study of Korean-English bilinguals

Soyoung Suh — 2007-03-21T20:49:10-00:00

Brain Research, Vol. 1136, No. 1. (9 March 2007), pp. 178-189.

The neural mechanisms underlying the syntactic processing of sentence comprehension in Korean (L1) and English (L2) by late bilinguals were investigated using functional MRI. The Korean native speakers were asked to read sentences with different levels of syntactic complexity in L1 and L2 and respond to comprehension questions concerning the sentences. The syntactic complexity was varied using a center-embedded sentence "The director that the maid introduced ignored the farmer" or a conjoined sentence "The maid introduced the director and ignored the farmer". It was found that the major areas involved in sentence processing such as the left inferior frontal gyrus (IFG), bilateral inferior parietal gyrus, and occipital lobe including cuneus, and lingual gyrus were commonly activated during the processing of both L1 and L2. However, the pattern of activation was different for L1 and L2 in the left IFG. The amount of activation was greater for embedded sentences than for conjoined sentences in L1 while no difference was found in L2. These results suggest that the cortical areas involved with syntactic processing in L1 and L2 are shared, but that the underlying neural mechanisms are different. The findings of the present study are discussed in comparison with Hasegawa et al.'s (Hasegawa, M., Carpenter, P.A., Just, M.A., 2002. An fMRI study of bilingual sentence comprehension and workload. NeuroImage 15, 647-660.) and Yokoyama et al.'s (Yokoyama, S., Okamoto, H., Miyamoto, T., Yoshimoto, K., Kim, J., Iwata, K., Jeong, H., Uchida, S., Ikuta, N., Sassa, Y., Nakamura, W., Horie, K., Sato, S., Kawashima, R., 2006. Cortical activation in the processing of passive sentences in L1 and L2: An fMRI study. NeuroImage 30, 570-579.) studies which also found common areas of activation but different patterns of activation during the processing of L1 and L2.

The attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain.

MF Rushworth — 2007-05-16T16:53:05-00:00

J Cogn Neurosci, Vol. 13, No. 5. (1 July 2001), pp. 698-710.

It is widely agreed that visuospatial orienting attention depends on a network of frontal and parietal areas in the right hemisphere. It is thought that the visuospatial orienting role of the right parietal lobe is related to its role in the production of overt eye movements. The experiments reported here test the possibility that other parietal regions may be important for directing attention in relation to response modalities other than eye movement. Specifically, we used positron emission tomography (PET) to test the hypothesis that a 'left' parietal area, the supramarginal gyrus, is important for attention in relation to limb movements (Rushworth et al., 1997; Rushworth, Ellison, & Walsh, in press). We have referred to this process as 'motor attention' to distinguish it from orienting attention. In one condition subjects spent most of the scanning period covertly attending to 'left' hand movements that they were about to make. Activity in this first condition was compared with a second condition with identical stimuli and movement responses but lacking motor attention periods. Comparison of the conditions revealed that motor attention-related activity was almost exclusively restricted to the 'left' hemisphere despite the fact that subjects only ever made ipsilateral, left-hand responses. Left parietal activity was prominent in this comparison, within the parietal lobe the critical region for motor attention was the supramarginal gyrus and the adjacent anterior intraparietal sulcus (AIP), a region anterior to the posterior parietal cortex identified with orienting attention. In a second part of the experiment we compared a condition in which subjects covertly rehearsed verbal responses with a condition in which they made verbal responses immediately without rehearsal. A comparison of the two conditions revealed verbal rehearsal-related activity in several anterior left hemisphere areas including Broca's area. The lack of verbal rehearsal-related activity in the left supra-marginal gyrus confirms that this area plays a direct role in motor attention that cannot be attributed to any strategy of verbal mediation. The results also provide evidence concerning the importance of ventral premotor (PMv) and Broca's area in motor attention and language processes.

The left parietal and premotor cortices: motor attention and selection

MFS Rushworth — 2008-03-27T23:27:49-00:00

NeuroImage, Vol. 20, No. Supplement 1. (November 2003), pp. S89-S100.

It is well established that the premotor cortex has a central role in the selection of movements. The role of parts of the parietal cortex in movement control has proved more difficult to describe but appears to be related to the preparation and the redirection of movements and movement intentions. We have referred to some of these processes as motor attention. It has been known since the time of William James that covert motor attention can be directed to an upcoming movement just as visuospatial attention can be directed to a location in space. While some parietal regions, particularly in the right hemisphere, are concerned with covert orienting and the redirecting of covert orienting it may be useful to consider other parietal regions, in the anterior inferior parietal lobule and in the posterior superior parietal lobule, particularly in the left hemisphere, as contributing to motor attention. Such parts of the parietal lobe are activated in neuroimaging experiments when subjects covertly prepare movements or switch intended movements. Lesions or transcranial magnetic stimulation (TMS) affect the redirecting of motor attention. The difficulties apraxic patients experience when sequencing movements may partly be due to an inability to redirect motor attention from one movement to another. The role of the premotor cortex in selecting movements is also lateralized to the left hemisphere. Damage to left hemisphere movement selection mechanisms may also contribute to apraxia. If, however, it remains intact after a stroke then the premotor cortex may contribute to the recovery of arm movements. A group of patients with unilateral left hemisphere lesions and impaired movements in the contralateral right hand was studied. Functional magnetic resonance imaging showed that in some cases the premotor cortex in the intact hemisphere was more active when the stroke-affected hand was used. TMS in the same area in the same patients had the most disruptive effect on movements. In summary, patterns of motor impairment and recovery seen after strokes can partly be explained with reference to the roles of the parietal and premotor cortices in motor attention and selection.

Early setting of grammatical processing in the bilingual brain.

I Wartenburger — 2008-03-27T23:26:43-00:00

Neuron, Vol. 37, No. 1. (9 January 2003), pp. 159-170.

The existence of a "critical period" for language acquisition is controversial. Bilingual subjects with variable age of acquisition (AOA) and proficiency level (PL) constitute a suitable model to study this issue. We used functional magnetic resonance imaging to investigate the effects of AOA and PL on neural correlates of grammatical and semantic judgments in Italian-German bilinguals who learned the second language at different ages and had different proficiency levels. While the pattern of brain activity for semantic judgment was largely dependent on PL, AOA mainly affected the cortical representation of grammatical processes. These findings support the view that both AOA and PL affect the neural substrates of second language processing, with a differential effect on grammar and semantics.

Left putaminal activation when speaking a second language: evidence from PET.

D Klein — 2008-03-27T23:25:52-00:00

Neuroreport, Vol. 5, No. 17. (21 November 1994), pp. 2295-2297.

The neural representation of the languages of the polyglot speaker has been highly controversial. We used positron emission tomography (PET) to investigate whether production in a second language (L2) involves the same neural substrates as that of a first language (L1) in normal bilingual subjects who learned L2 after the age of 5 years. Comparison of cerebral blood flow (CBF) when repeating words in L2 and repeating words in L1 yielded only a single significant CBF change: an increase in the left putamen. We hypothesize that this region plays a specific role for articulation in L2. The role of the putamen in articulation is supported by foreign accent syndrome (FAS), which can occur after left putaminal damage. The increased articulatory demands imposed by speaking a second language may require complex motor control for speech production in L2.

Language Control in the Bilingual Brain

J Crinion — 2006-06-10T15:37:19-00:00

Science, Vol. 312, No. 5779. (9 June 2006), pp. 1537-1540.

How does the bilingual brain distinguish and control which language is in use? Previous functional imaging experiments have not been able to answer this question because proficient bilinguals activate the same brain regions irrespective of the language being tested. Here, we reveal that neuronal responses within the left caudate are sensitive to changes in the language or the meaning of words. By demonstrating this effect in populations of German-English and Japanese-English bilinguals, we suggest that the left caudate plays a universal role in monitoring and controlling the language in use. 10.1126/science.1127761

Prefrontal cortex and basal ganglia control access to working memory.

Fiona McNab — 2007-12-17T21:10:03-00:00

Nat Neurosci (9 December 2007)

Our capacity to store information in working memory might be determined by the degree to which only relevant information is remembered. The question remains as to how this selection of relevant items to be remembered is accomplished. Here we show that activity in the prefrontal cortex and basal ganglia preceded the filtering of irrelevant information and that activity, particularly in the globus pallidus, predicted the extent to which only relevant information is stored. The preceding frontal and basal ganglia activity were also associated with inter-individual differences in working memory capacity. These findings reveal a mechanism by which frontal and basal ganglia activity exerts attentional control over access to working memory storage in the parietal cortex in humans, and makes an important contribution to inter-individual differences in working memory capacity.

Converging Evidence for a Fronto-Basal-Ganglia Network for Inhibitory Control of Action and Cognition

Adam Aron — 2007-12-19T22:52:04-00:00

J. Neurosci., Vol. 27, No. 44. (31 October 2007), pp. 11860-11864.

10.1523/JNEUROSCI.3644-07.2007

Triangulating a cognitive control network using diffusion-weighted magnetic resonance imaging (MRI) and functional MRI.

AR Aron — 2007-06-01T15:36:11-00:00

J Neurosci, Vol. 27, No. 14. (4 April 2007), pp. 3743-3752.

The ability to stop motor responses depends critically on the right inferior frontal cortex (IFC) and also engages a midbrain region consistent with the subthalamic nucleus (STN). Here we used diffusion-weighted imaging (DWI) tractography to show that the IFC and the STN region are connected via a white matter tract, which could underlie a "hyperdirect" pathway for basal ganglia control. Using a novel method of "triangulation" analysis of tractography data, we also found that both the IFC and the STN region are connected with the presupplementary motor area (preSMA). We hypothesized that the preSMA could play a conflict detection/resolution role within a network between the preSMA, the IFC, and the STN region. A second experiment tested this idea with functional magnetic resonance imaging (fMRI) using a conditional stop-signal paradigm, enabling examination of behavioral and neural signatures of conflict-induced slowing. The preSMA, IFC, and STN region were significantly activated the greater the conflict-induced slowing. Activation corresponded strongly with spatial foci predicted by the DWI tract analysis, as well as with foci activated by complete response inhibition. The results illustrate how tractography can reveal connections that are verifiable with fMRI. The results also demonstrate a three-way functional-anatomical network in the right hemisphere that could either brake or completely stop responses.

Automatic behaviour: Efficient not mindless

LL Saling — 2008-03-27T23:16:06-00:00

Brain Research Bulletin, Vol. 73, No. 1-3. (15 June 2007), pp. 1-20.

Automaticity is a core construct underpinning theoretical accounts of human performance and cognition. In spite of this, its current conceptualisation is plagued by circularity - automaticity is typically defined in terms of the very behaviour it seeks to explain - and a lack of internal consistency--defining features of automaticity do not reliably co-occur. Furthermore, invoking automaticity tends to be post hoc as it is used to explain violations of dominant theories of attention. Prevailing models of automaticity explain automatic processing as merely faster processing than controlled processing. We present an alternative conceptualisation of automaticity as efficient, elegant and economical but not fast. This is supported by functional imaging studies, which reveal a pattern of reduced global activation as well as a shift in activation from cortical to subcortical areas once automaticity has been achieved. Were automaticity to be faster processing, functional imaging would indicate greater activation when an automatic task is performed. We propose possible circuitry of automaticity incorporating the direct pathways of the basal ganglia.

Dissociation of neural systems mediating shifts in behavioral response and cognitive set.

KM Shafritz — 2005-11-04T21:58:40-00:00

Neuroimage, Vol. 25, No. 2. (1 April 2005), pp. 600-606.

The ability to generate appropriate behaviors in response to changing situations requires both the alteration of ongoing behavior and the understanding of the global rules governing stimulus categorization in a given context. Neuropsychological tests that have been developed to measure this form of cognitive flexibility, such as the Wisconsin Card Sorting Test, have reliably demonstrated that individuals with lesions in regions of the prefrontal cortex and basal ganglia have difficulty generating a cognitive set and altering rule-governed behavior. Recent neuroimaging studies have supported the role of these brain regions in the performance of response shifting and cognitive set shifting. However, the precise role of these regions in the individual components of these tasks remains a contentious issue. Here, we used event-related functional magnetic resonance imaging (fMRI) to dissociate the neural circuitry involved in the alteration of ongoing behavior and the shifting of cognitive set. Participants viewed geometric shapes as they appeared individually in rapid succession and responded with an appropriate button press based upon whether the individual shape was a predetermined target stimulus. Responses were required for each shape presented. The fMRI results indicated that response shifting specifically activated a dorsal neural circuit comprised of the dorsolateral prefrontal cortex, anterior cingulate, and intraparietal sulcus. Shifts in cognitive set were mediated by ventrolateral prefrontal cortex, anterior cingulate, and striatum. These findings suggest that the alteration of ongoing behavior and shifting of cognitive set are mediated by two distinct neural systems interconnected by the anterior cingulate.

The human striatum is necessary for responding to changes in stimulus relevance.

R Cools — 2008-03-27T23:13:59-00:00

J Cogn Neurosci, Vol. 18, No. 12. (December 2006), pp. 1973-1983.

Various lines of evidence suggest that the striatum is implicated in cognitive flexibility. The neuropsychological evidence has, for the most part, been based on research with patients with Parkinson's disease, which is accompanied by chemical disruption of both the striatum and the prefrontal cortex. The present study examined this issue by testing patients with focal lesions of the striatum on a task measuring two forms of cognitive switching. Patients with striatal, but not frontal lobe lesions, were impaired in switching between concrete sensory stimuli. By contrast, both patient groups were unimpaired when switching between abstract task rules relative to baseline nonswitch trials. These results reveal a dissociation between two distinct forms of cognitive flexibility, providing converging evidence for a role of the striatum in flexible control functions associated with the selection of behaviorally relevant stimuli.

The contribution of the medial prefrontal cortex, orbitofrontal cortex, and dorsomedial striatum to behavioral flexibility.

ME Ragozzino — 2008-03-27T23:12:37-00:00

Ann N Y Acad Sci, Vol. 1121 (December 2007), pp. 355-375.

Behavioral flexibility refers to the ability to shift strategies or response patterns with a change in environmental contingencies. The frontal lobe and basal ganglia are two brain regions implicated in various components for successfully adapting to changed environmental contingencies. This paper discusses a series of experiments that investigate the contributions of the rat prelimbic area, infralimbic area, orbitofrontal cortex, and dorsomedial striatum to behavioral flexibility. Orbitofrontal cortex inactivation did not impair initial learning of discrimination tests, but it impaired reversal learning due to perseverance in the previously learned choice pattern. Inactivation of the prelimbic area did not affect acquisition or reversal learning of different discrimination tests, but it selectively impaired learning when rats had to inhibit one strategy and shift to using a new strategy. However, comparable to orbitofrontal cortex inactivation, strategy-switching deficits following prelimbic inactivation resulted from a perseverance of the previously relevant strategy. Fewer studies have examined the infralimbic region, but there is some evidence suggesting that this region supports reversal learning by maintaining the reliable execution of a new choice pattern. Dorsomedial striatal inactivation impaired both reversal learning and strategy switching. The behavioral flexibility deficits following dorsomedial striatal inactivation resulted from the inability to maintain a new choice pattern once selected. Taken together, the results suggest that orbitofrontal and prelimbic subregions differentially contribute to behavioral flexibility, but they are both critical for the initial inhibition of a previously learned strategy, while the dorsomedial striatum plays a broader role in behavioral flexibility and supports a process that allows the reliable execution of a new strategy once selected.

Thalamic-prefrontal cortical-ventral striatal circuitry mediates dissociable components of strategy set shifting.

AE Block — 2008-03-27T23:00:43-00:00

Cereb Cortex, Vol. 17, No. 7. (July 2007), pp. 1625-1636.

The mediodorsal nuclei of thalamus (MD), prefrontal cortex (PFC), and nucleus accumbens core (NAc) form an interconnected network that may work together to subserve certain forms of behavioral flexibility. The present study investigated the functional interactions between these regions during performance of a cross-maze-based strategy set-shifting task. In Experiment 1, reversible bilateral inactivation of the MD via infusions of bupivacaine did not impair simple discrimination learning, but did disrupt shifting from response to visual cue discrimination strategy, and vice versa. This impairment was due to an increase in perseverative errors. In Experiment 2, asymmetrical disconnection inactivations of the MD on one side of the brain and PFC on the other also caused a perseverative deficit when rats were required to shift from a response to a visual cue discrimination strategy, as did disconnections between the PFC and the NAc. However, inactivation of the MD on one side of the brain and the NAc contralaterally resulted in a selective increase in never-reinforced errors, suggesting this pathway is important for eliminating inappropriate strategies during set shifting. These data indicate that set shifting is mediated by a distributed neural circuit, with separate neural pathways contributing dissociable components to this type of behavioral flexibility.

Learning and memory functions of the Basal Ganglia.

MG Packard — 2007-02-22T03:57:16-00:00

Annu Rev Neurosci, Vol. 25 (2002), pp. 563-593.

Although the mammalian basal ganglia have long been implicated in motor behavior, it is generally recognized that the behavioral functions of this subcortical group of structures are not exclusively motoric in nature. Extensive evidence now indicates a role for the basal ganglia, in particular the dorsal striatum, in learning and memory. One prominent hypothesis is that this brain region mediates a form of learning in which stimulus-response (S-R) associations or habits are incrementally acquired. Support for this hypothesis is provided by numerous neurobehavioral studies in different mammalian species, including rats, monkeys, and humans. In rats and monkeys, localized brain lesion and pharmacological approaches have been used to examine the role of the basal ganglia in S-R learning. In humans, study of patients with neurodegenerative diseases that compromise the basal ganglia, as well as research using brain neuroimaging techniques, also provide evidence of a role for the basal ganglia in habit learning. Several of these studies have dissociated the role of the basal ganglia in S-R learning from those of a cognitive or declarative medial temporal lobe memory system that includes the hippocampus as a primary component. Evidence suggests that during learning, basal ganglia and medial temporal lobe memory systems are activated simultaneously and that in some learning situations competitive interference exists between these two systems.

Effect of bilingualism on cognitive control in the Simon task: evidence from MEG.

E Bialystok — 2008-03-27T22:58:49-00:00

Neuroimage, Vol. 24, No. 1. (1 January 2005), pp. 40-49.

The present study used magneto-encephalography (MEG) to determine the neural correlates of the bilingual advantage previously reported for behavioral measures in conflict tasks. Bilingual Cantonese-English, bilingual French-English, and monolingual English speakers, performed the Simon task in the MEG. Reaction times were faster for congruent than for incongruent trials, and the Cantonese group was faster than the other two groups, which did not differ from each other. Analyses of the MEG data using synthetic aperture magnetometry (SAM) and partial last squares (PLS) showed that the same pattern of activity, involving signal changes in left and medial prefrontal areas, characterized all three groups. Correlations between activated regions and reaction times, however, showed that the two bilingual groups demonstrated faster reaction times with greater activity in superior and middle temporal, cingulate, and superior and inferior frontal regions, largely in the left hemisphere. The monolinguals demonstrated faster reaction times with activation in middle frontal regions. The interpretation is that the management of two language systems led to systematic changes in frontal executive functions.

An integrative theory of prefrontal cortex function.

EK Miller — 2006-01-23T23:03:09-00:00

Annu Rev Neurosci, Vol. 24 (2001), pp. 167-202.

The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

A topography of executive functions and their interactions revealed by functional magnetic resonance imaging

C Fassbender — 2008-03-27T22:50:46-00:00

Cognitive Brain Research, Vol. 20, No. 2. (July 2004), pp. 132-143.

We used fMRI to study the brain processes involved in the executive control of behavior. The Sustained Attention to Response Task (SART), which allows unpredictable and predictable NOGO events to be contrasted, was imaged using a mixed (block and event-related) fMRI design to examine tonic and phasic processes involved in response inhibition, error detection, conflict monitoring and sustained attention. A network of regions, including right ventral prefrontal cortex (PFC), left dorsolateral PFC (DLPFC) and right inferior parietal cortex, was activated for successful unpredictable inhibitions, while rostral anterior cingulate was implicated in error processing and the pre-SMA in conflict monitoring. Furthermore, the pattern of correlations between left dorsolateral PFC, implicated in task-set maintenance, and the pre-SMA were indicative of a tight coupling between prefrontally mediated control and conflict levels monitored more posteriorly. The results reveal that the executive control of behavior can be separated into distinct functions performed by discrete cortical regions.

Conflict monitoring and anterior cingulate cortex: an update.

MM Botvinick — 2006-03-25T15:09:42-00:00

Trends Cogn Sci, Vol. 8, No. 12. (December 2004), pp. 539-546.

One hypothesis concerning the human dorsal anterior cingulate cortex (ACC) is that it functions, in part, to signal the occurrence of conflicts in information processing, thereby triggering compensatory adjustments in cognitive control. Since this idea was first proposed, a great deal of relevant empirical evidence has accrued. This evidence has largely corroborated the conflict-monitoring hypothesis, and some very recent work has provided striking new support for the theory. At the same time, other findings have posed specific challenges, especially concerning the way the theory addresses the processing of errors. Recent research has also begun to shed light on the larger function of the ACC, suggesting some new possibilities concerning how conflict monitoring might fit into the cingulate's overall role in cognition and action.

The prefrontal cortex and flexible behavior.

H Barbas — 2008-02-04T19:29:37-00:00

Neuroscientist, Vol. 13, No. 5. (October 2007), pp. 532-545.

The prefrontal cortex in primates guides behavior by selecting relevant stimuli for the task at hand, mediated through excitatory bidirectional pathways with structures associated with sensory processing, memory, and emotions. The prefrontal cortex also has a key role in suppressing irrelevant stimuli through a mechanism that is not well understood. Recent findings indicate that prefrontal pathways interface with laminar-specific neurochemical classes of inhibitory neurons in sensory cortices, terminate extensively in the frontal and sensory sectors of the inhibitory thalamic reticular nucleus, and target the inhibitory intercalated masses of the amygdala. Circuit-based models suggest that prefrontal pathways can select relevant signals and efficiently suppress distractors, in processes that are disrupted in schizophrenia and in other disorders affecting prefrontal cortices.

Working memory and executive function: evidence from neuroimaging.

PA Carpenter — 2007-05-16T17:31:03-00:00

Curr Opin Neurobiol, Vol. 10, No. 2. (April 2000), pp. 195-199.

Traditional theories of working memory and executive function, when mapped in straightforward ways into the neural domain, yield predictions that are only partly supported by the recent neuroimaging studies. Neuroimaging studies suggest that some constituent functions, such as maintaining information in active form and manipulating it, are not discretely localized in prefrontal regions. Some hypothesized executive processes, such as goal management, have effects in several cortical regions, including posterior regions. Such results suggest a more dynamic and distributed view of the cortical organization of working memory and executive functions.

Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging

Jeffrey Binder — 2007-02-05T16:35:23-00:00

J. Neurosci., Vol. 17, No. 1. (1 January 1997), pp. 353-362.

Psychobiology of plasticity: effects of training and experience on brain and behavior

Mark Rosenzweig — 2008-03-27T22:43:30-00:00

Behavioural Brain Research, Vol. 78, No. 1. (June 1996), pp. 57-65.

Supporting Hebb's 1949 hypothesis of use-induced plasticity of the nervous system, our group found in the 1960s that training or differential experience induced neurochemical changes in cerebral cortex of the rat and regional changes in weight of cortex. Further studies revealed changes in cortical thickness, size of synaptic contacts, number of dendritic spines, and dendritic branching. Similar effects were found whether rats were assigned to differential experience at weaning (25 days of age), as young adults (105 days) or as adults (285 days). Enriched early experience improved performance on several tests of learning. Cerebral results of experience in an enriched environment are similar to results of formal training. Enriched experience and training appear to evoke the same cascade of neurochemical events in causing plastic changes in brain. Sufficiently rich experience may be necessary for full growth of species-specific brain characteristics and behavioral potential. Clayton and Krebs found in 1994 that birds that normally store food have larger hippocampi than related species that do not store. This difference develops only in birds given the opportunity to store and recover food. Research on use-induced plasticity is being applied to promote child development, successful aging, and recovery from brain damage; it is also being applied to benefit animals in laboratories, zoos and farms.

Functional MRI cerebral activation and deactivation during finger movement.

JD Allison — 2005-08-19T13:11:24-00:00

Neurology, Vol. 54, No. 1. (11 January 2000), pp. 135-142.

OBJECTIVE: To examine interhemispheric interactions of motor processes by using functional MRI (fMRI). BACKGROUND: Despite evidence of interhemispheric inhibition from animal, clinical, and transcranial magnetic stimulation (TMS) studies, fMRI has not been used to explore activation and deactivation during unilateral motor tasks. fMRI changes associated with motor activity have traditionally been described by comparing cerebral activation during motor tasks relative to a "resting state." In addition to this standard comparison, we examined fMRI changes in the resting state relative to a motor task. METHODS: Thirteen healthy volunteers performed self-paced sequential finger/thumb tapping for each hand. During fMRI data acquisition, four epochs were obtained; each comprised of 30 seconds of rest, 30 seconds of right hand activity, and 30 seconds of left hand activity. Resultant echoplanar images were spatially normalized and spatially and temporally smoothed. RESULTS: As expected, hand movements produced activation in the contralateral sensorimotor cortex and adjacent subcortical regions and, when present, the ipsilateral cerebellum. However, hand movement also produced a significant deactivation (i.e., decreased blood flow) in the ipsilateral sensorimotor cortex and subcortical regions, and when present, the contralateral cerebellum. Conjunction analysis demonstrated regions that are activated by one hand and deactivated by the contralateral hand. CONCLUSION: Unilateral hand movements are associated with contralateral cerebral activation and ipsilateral cerebral deactivation, which we hypothesize result from transcallosal inhibition.

Paul Broca's historic cases: high resolution MR imaging of the brains of Leborgne and Lelong.

NF Dronkers — 2008-03-27T22:41:07-00:00

Brain, Vol. 130, No. Pt 5. (May 2007), pp. 1432-1441.

In 1861, the French surgeon, Pierre Paul Broca, described two patients who had lost the ability to speak after injury to the posterior inferior frontal gyrus of the brain. Since that time, an infinite number of clinical and functional imaging studies have relied on this brain-behaviour relationship as their anchor for the localization of speech functions. Clinical studies of Broca's aphasia often assume that the deficits in these patients are due entirely to dysfunction in Broca's area, thereby attributing all aspects of the disorder to this one brain region. Moreover, functional imaging studies often rely on activation in Broca's area as verification that tasks have successfully tapped speech centres. Despite these strong assumptions, the range of locations ascribed to Broca's area varies broadly across studies. In addition, recent findings with language-impaired patients have suggested that other regions also play a role in speech production, some of which are medial to the area originally described by Broca on the lateral surface of the brain. Given the historical significance of Broca's original patients and the increasing reliance on Broca's area as a major speech centre, we thought it important to re-inspect these brains to determine the precise location of their lesions as well as other possible areas of damage. Here we describe the results of high resolution magnetic resonance imaging of the preserved brains of Broca's two historic patients. We found that both patients' lesions extended significantly into medial regions of the brain, in addition to the surface lesions observed by Broca. Results also indicate inconsistencies between the area originally identified by Broca and what is now called Broca's area, a finding with significant ramifications for both lesion and functional neuroimaging studies of this well-known brain area.

Cognitive control and parsing: reexamining the role of Broca's area in sentence comprehension.

JM Novick — 2008-03-27T22:38:57-00:00

Cogn Affect Behav Neurosci, Vol. 5, No. 3. (September 2005), pp. 263-281.

A century of investigation into the role of the human frontal lobes in complex cognition, including language processing, has revealed several interesting but apparently contradictory findings. In particular, the results of numerous studies suggest that left inferior frontal gyrus (LIFG), which includes Broca's area, plays a direct role in sentence-level syntactic processing. In contrast, other brain-imaging and neuropsychological data indicate that LIFG is crucial for cognitive control--specifically, for overriding highly regularized, automatic processes, even when a task involves syntactically undemanding material (e.g., single words, a list of letters). We provide a unifying account of these findings, which emphasizes the importance of general cognitive control mechanisms for the syntactic processing of sentences. On the basis of a review of the neurocognitive and sentence-processing literatures, we defend the following three hypotheses: (1) LIFG is part of a network of frontal lobe subsystems that are generally responsible for the detection and resolution of incompatible stimulus representations; (2) the role of LIFG in sentence comprehension is to implement reanalysis in the face of misinterpretation; and (3) individual differences in cognitive control abilities in nonsyntactic tasks predict correlated variation in sentence-processing abilities pertaining to the recovery from misinterpretation.

From Perception to Sentence Comprehension: The Convergence of Auditory and Visual Information of Language in the Left Inferior Frontal Cortex

Fumitaka Homae — 2008-03-27T22:38:02-00:00

NeuroImage, Vol. 16, No. 4. (August 2002), pp. 883-900.

We used functional magnetic resonance imaging (fMRI) to characterize cortical activation associated with sentence processing, thereby elucidating where in the brain auditory and visual inputs of words converge during sentence comprehension. Within one scanning session, subjects performed three types of tasks with different linguistic components from perception to sentence comprehension: nonword (NAV; auditory and visual), phrase (P; either auditory or visual), and sentence (S; either auditory or visual) tasks. In a comparison of the P and NAV tasks, the angular and supramarginal gyri showed bilateral activation, whereas the inferior and middle frontal gyri showed left-lateralized activation. A comparison of the S and P tasks, together with a conjunction analysis, revealed a ventral region of the left inferior frontal gyrus (F3t/F3O), which was sentence-processing selective and modality-independent. These results unequivocally demonstrated that the left F3t/F3O is involved in the selection and integration of semantic information that are separable from lexico-semantic processing.

The role of age of acquisition and language usage in early, high-proficient bilinguals: an fMRI study during verbal fluency.

D Perani — 2008-03-27T22:33:13-00:00

Hum Brain Mapp, Vol. 19, No. 3. (July 2003), pp. 170-182.

We assessed the effects of age of acquisition and language exposure on the cerebral correlates of lexical retrieval in high-proficient, early-acquisition bilinguals. Functional MRI was used to study Spanish-Catalan bilinguals who acquired either Spanish or Catalan as a first language in the first years of life. Subjects were exposed to the second language at 3 years of age, and have used both languages in daily life since then. Subjects had a comparable level of proficiency in the comprehension of both languages. Lexical retrieval with the verbal fluency task resulted in the well-established pattern of left hemispheric activation centered on the inferior frontal region. The effect of age of acquisition was assessed by dividing the subjects into two groups, on the basis of the language acquired first (Catalan-born or Spanish-born bilinguals). Functional comparisons indicated that less extensive brain activation was associated with lexical retrieval in the language acquired earlier in life. The two groups were also different in language usage/exposure, as assessed with a specific questionnaire; in particular, the exposure to the second language (Spanish) was less intensive in the case of Catalans. This was reflected in a significant interaction, indicating a more extensive activation in Catalans during production in Spanish. Overall, these results indicate that, during a production task, both age of acquisition and language exposure affect the pattern of brain activation in bilinguals, even if both languages are acquired early and with a comparable level of proficiency.

The development of inhibitory control in preschool children: effects of "executive skills" training.

SM Dowsett — 2008-03-27T22:31:51-00:00

Dev Psychobiol, Vol. 36, No. 2. (March 2000), pp. 161-174.

As one of several processes involved in the executive functioning of the cognitive system, inhibitory control plays a significant role in determining how various mental processes work together in the successful performance of a task. Studies of response inhibition have shown that although 3-year-old children have the cognitive capacity to learn the rules required for response control, indicated by the correct verbal response, developmental constraints prevent them from withholding the correct response (Bell & Livesey, 1985; Livesey & Morgan, 1991). Some argue that these abulic dissociations are relative to children's ability to reflect on the rules required for response control (Zelazo, Reznick, & Pinon, 1995). The current study showed that repeated exposure to tasks facilitating the acquisition of increasingly complex rule structures could improve inhibitory control (as measured by a go/no-go discrimination learning task), even in children aged 3 years. These tasks included a variant of Diamond and Boyer's (1989) modified version of the Wisconsin Card Sort Task and a simplification of the change paradigm (Logan & Burkell, 1986). It is argued that experience with these tasks increased the acquisition of complex rules by placing demands on executive processes. This includes response control and other executive functions, such as representational flexibility, the ability to maintain information in working memory, the selective control of attention, and proficiency at error correction. The role of experiential variables in the development of inhibitory control is discussed in terms of the interaction between neural development and appropriate executive task experience in the early years.

Processing speed, executive function, and age differences in remembering and knowing.

D Bunce — 2008-03-27T22:30:55-00:00

Q J Exp Psychol A, Vol. 58, No. 1. (January 2005), pp. 155-168.

A group of young (n = 52, M = 23.27 years) and old (n = 52, M = 68.62 years) adults studied two lists of semantically unrelated nouns. For one list a time of 2 s was allowed for encoding, and for the other, 5 s. A recognition test followed where participants classified their responses according to Gardiner's (1988) remember-know procedure. Age differences for remembering and knowing were minimal in the faster 2-s encoding condition. However, in the longer 5-s encoding condition, younger persons produced significantly more remember responses, and older adults a greater number of know responses. This dissociation suggests that in the longer encoding condition, younger adults utilized a greater level of elaborative rehearsal governed by executive processes, whereas older persons employed maintenance rehearsal involving short-term memory. Statistical control procedures, however, found that independent measures of processing speed accounted for age differences in remembering and knowing and that independent measures of executive control had little influence. The findings are discussed in the light of contrasting theoretical accounts of recollective experience in old age.

The effect of aging in recollective experience: The processing speed and executive functioning hypothesis

Aurelia Bugaiska — 2008-03-27T22:29:20-00:00

Consciousness and Cognition, Vol. 16, No. 4. (December 2007), pp. 797-808.

This study was designed to investigate the effects of aging on consciousness in recognition memory, using the Remember/Know/Guess procedure (Gardiner, J. M., & Richarson-Klavehn, A. (2000). Remembering and Knowing. In E. Tulving & F. I. M. Craik (Eds.), The Oxford Handbook of Memory. Oxford University Press.). In recognition memory, older participants report fewer occasions on which recognition is accompanied by recollection of the original encoding context. Two main hypotheses were tested: the speed mediation hypothesis (Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 3, 403-428) and the executive-aging hypothesis (West, R. L. (1996). An application of prefrontal cortex function theory to cognitive aging. Psychological Bulletin, 120, 272-292). A group of young and a group of older adults took a recognition test in which they classified their responses according to Gardiner, J. M., & Richarson-Klavehn, A. (2000). Remembering and Knowing. In E. Tulving & F. I. M. Craik (Eds.), The Oxford Handbook of Memory. Oxford University Press. remember-know-guess paradigm. Subsequently, participants completed processing speed and executive function tests. The results showed that among the older participants, R responses decreased, but K responses did not. Moreover, a hierarchical regression analysis supported the view that the effect of age in recollection experience is determined by frontal lobe integrity and not by diminution of processing speed.

Exercise, experience and the aging brain

James Churchill — 2008-03-27T22:28:35-00:00

Neurobiology of Aging, Vol. 23, No. 5. ( 2002), pp. 941-955.

While limited research is available, evidence indicates that physical and mental activity influence the aging process. Human data show that executive functions of the type associated with frontal lobe and hippocampal regions of the brain may be selectively maintained or enhanced in humans with higher levels of fitness. Similarly enhanced performance is observed in aged animals exposed to elevated physical and mental demand and it appears that the vascular component of the brain response may be driven by physical activity whereas the neuronal component may reflect learning. Recent results have implicated neurogenesis, at least in the hippocampus, as a component of the brain response to exercise, with learning enhancing survival of these neurons. Non-neuronal tissues also respond to experience in the mature brain, indicating that the brain reflects both its recent and its longer history of experience. Preliminary measures of brain function hold promise of increased interaction between human and animal researchers and a better understanding of the substrates of experience effects on behavioral performance in aging.

Characteristic functional networks in high- versus low-proficiency second language speakers detected also during native language processing: An explorative EEG coherence study in 6 frequency bands

Susanne Reiterer — 2006-04-10T22:20:29-00:00

Cognitive Brain Research, Vol. 25, No. 2. (October 2005), pp. 566-578.

An EEG coherence study was performed with a twofold objective: first, to scrutinize the theoretical concept of "cortical efficiency" in connection with second language (L2) acquisition and, second, to detect cooperations between cortical areas in specific frequency bands indicative for highly proficient L2 processing. Two groups differing only in their level of L2 proficiency were contrasted during presentation of natural language videos in English (L2) and German (native language, L1), with explorative coherence analysis in 6 frequency bands (0.5-31.5 Hz). The coherence brain maps revealed more pronounced and widespread increases in coherences in the [alpha]1-band (8-10 Hz) in low-proficiency than in the high-proficiency L2 speakers. Surprisingly, this difference was obtained also during L1 processing and corroborated for both languages by multivariate permutation tests. These tests revealed additional differences between the low- and the high-proficiency group also for coherences within the [beta]1- (13-18 Hz) and the [beta]2-band (18.5-31.5 Hz), again during L2 and L1 processing. Since the same group differences were observed during L1 and L2 processing, our high-proficiency group might have profited from a more generic advantage in language or text processing strategy. This strategic advantage was most evident at [alpha]1 frequencies, possibly related to a specific way of processing internal mental states (top-down processing).

Who's in Control? Proficiency and L1 Influence on L2 Processing

Kerrie Elston-Guttler — 2006-12-05T19:43:01-00:00

J. Cogn. Neurosci., Vol. 17, No. 10. (1 October 2005), 1593.

We report three reaction time (RT)/event-related brain potential (ERP) semantic priming lexical decision experiments that explore the following in relation to L1 activation during L2 processing: (1) the role of L2 proficiency, (2) the role of sentence context, and (3) the locus of L1 activations (orthographic vs. semantic). All experiments used German (L1) homonyms translated into English (L2) to form prime-target pairs (pine-jaw for Kiefer) to test whether the L1 caused interference in an all-L2 experiment. Both RTs and ERPs were measured on targets. Experiment 1 revealed reversed priming in the N200 component and RTs for low-proficiency learners, but only RT interference for high-proficiency participants. Experiment 2 showed that once the words were processed in sentence context, the low-proficiency participants still showed reversed N200 and RT priming, whereas the high-proficiency group showed no effects. Experiment 3 tested native English speakers with the words in sentence context and showed a null result comparable to the high-proficiency group. Based on these results, we argue that cognitive control relating to translational activation is modulated by (1) L2 proficiency, as the early interference in the N200 was observed only for low-proficiency learners, and (2) sentence context, as it helps high-proficiency learners control L1 activation. As reversed priming was observed in the N200 and not the N400 component, we argue that (3) the locus of the L1 activations was orthographic. Implications in terms of bilingual word recognition and the functional role of the N200 ERP component are discussed.

Brain potentials reveal unconscious translation during foreign-language comprehension.

G Thierry — 2008-03-27T22:14:59-00:00

Proc Natl Acad Sci U S A, Vol. 104, No. 30. (24 July 2007), pp. 12530-12535.

Whether the native language of bilingual individuals is active during second-language comprehension is the subject of lively debate. Studies of bilingualism have often used a mix of first- and second-language words, thereby creating an artificial "dual-language" context. Here, using event-related brain potentials, we demonstrate implicit access to the first language when bilinguals read words exclusively in their second language. Chinese-English bilinguals were required to decide whether English words presented in pairs were related in meaning or not; they were unaware of the fact that half of the words concealed a character repetition when translated into Chinese. Whereas the hidden factor failed to affect behavioral performance, it significantly modulated brain potentials in the expected direction, establishing that English words were automatically and unconsciously translated into Chinese. Critically, the same modulation was found in Chinese monolinguals reading the same words in Chinese, i.e., when Chinese character repetition was evident. Finally, we replicated this pattern of results in the auditory modality by using a listening comprehension task. These findings demonstrate that native-language activation is an unconscious correlate of second-language comprehension.

Bilingual lexical activation in sentence context

Ana Schwartz — 2008-03-27T22:12:55-00:00

Journal of Memory and Language, Vol. 55, No. 2. (August 2006), pp. 197-212.

The present study investigated the cognitive nature of second language (L2) lexical processing in sentence context. We examined bilinguals' L2 word recognition performance for language-ambiguous words [cognates (e.g., piano) and homographs (e.g., pan)] in two sentence context experiments with highly proficient Spanish-English bilinguals living in a bilingual community (Experiment 1) and with intermediate proficiency Spanish-English bilinguals living in a monolingual community (Experiment 2). To determine the influence of sentence constraint on cross-language activation, the critical words and their matched controls were inserted in low- and high-constraint sentences. In low-constraint sentences significant cognate facilitation was observed, suggesting that both languages were active and influencing processing. In high-constraint sentences, the effects of cognate facilitation were eliminated. This interaction between cognate status and sentence constraint demonstrates that sentence context can restrict non-selectivity when there is sufficient semantic information to suppress the non-target language. The fact that this interaction was observed for both bilingual groups suggests that even less proficient bilinguals, who do not communicate daily in the L2, can use context to constrain cross-language lexical competition. Implications for current models of bilingual lexical access are discussed.

The relations among inhibition and interference control functions: a latent-variable analysis.

NP Friedman — 2008-03-27T22:05:58-00:00

J Exp Psychol Gen, Vol. 133, No. 1. (March 2004), pp. 101-135.

This study used data from 220 adults to examine the relations among 3 inhibition-related functions. Confirmatory factor analysis suggested that Prepotent Response Inhibition and Resistance to Distractor Interference were closely related, but both were unrelated to Resistance to Proactive Interference. Structural equation modeling, which combined Prepotent Response Inhibition and Resistance to Distractor Interference into a single latent variable, indicated that 1 aspect of random number generation performance, task-switching ability, and everyday cognitive failures were related to Response-Distractor Inhibition, whereas reading span recall and unwanted intrusive thoughts were related to Resistance to Proactive Interference. These results suggest that the term inhibition has been overextended and that researchers need to be more specific when discussing and measuring inhibition-related functions.

Executive Function and the Frontal Lobes: A Meta-Analytic Review

Alvarez — 2006-07-04T22:51:23-00:00

Neuropsychology Review, Vol. 16, No. 1. (March 2006), pp. 17-42.

The Unity and Diversity of Executive Functions and Their Contributions to Complex "Frontal Lobe" Tasks: A Latent Variable Analysis

Akira Miyake — 2008-03-27T22:02:28-00:00

Cognitive Psychology, Vol. 41, No. 1. (August 2000), pp. 49-100.

This individual differences study examined the separability of three often postulated executive functions--mental set shifting ("Shifting"), information updating and monitoring ("Updating"), and inhibition of prepotent responses ("Inhibition")--and their roles in complex "frontal lobe" or "executive" tasks. One hundred thirty-seven college students performed a set of relatively simple experimental tasks that are considered to predominantly tap each target executive function as well as a set of frequently used executive tasks: the Wisconsin Card Sorting Test (WCST), Tower of Hanoi (TOH), random number generation (RNG), operation span, and dual tasking. Confirmatory factor analysis indicated that the three target executive functions are moderately correlated with one another, but are clearly separable. Moreover, structural equation modeling suggested that the three functions contribute differentially to performance on complex executive tasks. Specifically, WCST performance was related most strongly to Shifting, TOH to Inhibition, RNG to Inhibition and Updating, and operation span to Updating. Dual task performance was not related to any of the three target functions. These results suggest that it is important to recognize both the unity and diversity of executive functions and that latent variable analysis is a useful approach to studying the organization and roles of executive functions.

More use almost always means a smaller frequency effect: Aging, bilingualism, and the weaker links hypothesis

Tamar Gollan — 2008-03-27T22:00:03-00:00

Journal of Memory and Language, Vol. 58, No. 3. (April 2008), pp. 787-814.

The "weaker links" hypothesis proposes that bilinguals are disadvantaged relative to monolinguals on speaking tasks because they divide frequency-of-use between two languages. To test this proposal, we contrasted the effects of increased word use associated with monolingualism, language dominance, and increased age on picture naming times. In two experiments, younger and older bilinguals and monolinguals named pictures with high- or low-frequency names in English and (if bilingual) also in Spanish. In Experiment 1, slowing related to bilingualism and language dominance was greater for producing low- than high-frequency names. In Experiment 2, slowing related to aging was greater for producing low-frequency names in the dominant language, but when speaking the non-dominant language, increased age attenuated frequency effects and age-related slowing was limited exclusively to high-frequency names. These results challenge competition-based accounts of bilingual disadvantages in language production, and illustrate how between-group processing differences may emerge from cognitive mechanisms general to all speakers.

DRC, : A Dual Route Cascaded Model of Visual Word Recognition and Reading Aloud

Max Coltheart — 2006-11-29T05:51:33-00:00

Psychological Review, Vol. 108, No. 1. (January 2001), pp. 204-256.

This article describes the Dual Route Cascaded (DRC) model, a computational model of visual word recognition and reading aloud. The DRC is a computational realization of the dual-route theory of reading, and is the only computational model of reading that can perform the 2 tasks most commonly used to study reading: lexical decision and reading aloud. For both tasks, the authors show that a wide variety of variables that influence human latencies influence the DRC model's latencies in exactly the same way. The DRC model simulates a number of such effects that other computational models of reading do not, but there appear to be no effects that any other current computational model of reading can simulate but that the DRC model cannot. The authors conclude that the DRC model is the most successful of the existing computational models of reading.

William Healy (1869-1963): pioneer child psychiatrist and criminologist.

J Snodgrass — 2008-03-27T21:38:21-00:00

J Hist Behav Sci, Vol. 20, No. 4. (October 1984), pp. 332-339.

William Healy, M.D., a pioneer psychiatrist and criminologist, established the first child guidance clinic in the United States in 1909, and was an early advocate of both the "team approach" and the "child's own story" in treatment and research. One of the founders and the first president of the American Orthopsychiatric Association, Healy helped introduce Freudian thought into the United States. Among his contributions to the field of criminology are his book The Individual Delinquent (1915) and his "multifactor theory" of delinquency, which broadened the field and moved it away from European criminology's stress on genetic factors. Healy developed an elaborate methodology for the complete study of the offender by a variety of specialists. He was also a reformer in the field of corrections, based on his investigations of several institutions for delinquents.

Shared and separate systems in bilingual language processing: Converging evidence from eyetracking and brain imaging

Viorica Marian — 2008-03-27T21:35:04-00:00

Brain and Language, Vol. 86, No. 1. (July 2003), pp. 70-82.

The neurological and cognitive aspects of bilingual language processing were examined in late Russian-English bilinguals using headband-mounted eyetracking and functional neuroimaging. A series of three eyetracking studies suggested that, at early stages of word recognition, bilinguals can activate both languages in parallel, even when direct linguistic input is in one language only. A functional neuroimaging study suggested that, although the same general structures are active for both languages, differences within these general structures are present across languages and across levels of processing. For example, different centers of activation were associated with first versus second language processing within the left Inferior Frontal Gyrus, but not within the Superior Temporal Gyrus. We suggest that parallel activation (as found with eyetracking) and shared cortical structures (as found with fMRI) may be characteristic of early stages of language processing (such as phonetic processing), but the two languages may be using separate structures at later stages of processing (such as lexical processing).