CiteULike: mbregman's library [57 articles]

Eye movements during visual mental imagery

Fred Mast — 2006-04-23T22:39:13-00:00

Trends in Cognitive Sciences, Vol. 6, No. 7. (1 July 2002), pp. 271-272.

It has long been debated whether eye movements play a functional role in visual mental imagery. A recent paper by Laeng and Teodorescu presents new evidence that eye movements are stored as a spatial index that is used to arrange the component parts correctly when mental images are generated.

Control of attention shifts between vision and audition in human cortex.

S Shomstein — 2007-09-11T21:07:39-00:00

J Neurosci, Vol. 24, No. 47. (24 November 2004), pp. 10702-10706.

Selective attention contributes to perceptual efficiency by modulating cortical activity according to task demands. Visual attention is controlled by activity in posterior parietal and superior frontal cortices, but little is known about the neural basis of attentional control within and between other sensory modalities. We examined human brain activity during attention shifts between vision and audition. Attention shifts from vision to audition caused increased activity in auditory cortex and decreased activity in visual cortex and vice versa, reflecting the effects of attention on sensory representations. Posterior parietal and superior prefrontal cortices exhibited transient increases in activity that were time locked to the initiation of voluntary attention shifts between vision and audition. These findings reveal that the attentional control functions of posterior parietal and superior prefrontal cortices are not limited to the visual domain but also include the control of crossmodal shifts of attention.

Dual processes in reasoning

PC Wason — 2008-04-02T04:02:36-00:00

Cognition, Vol. 3 (1975), pp. 141-154.

Finding useful questions: on bayesian diagnosticity, probability, impact, and information gain.

JD Nelson — 2005-11-17T02:14:27-00:00

Psychol Rev, Vol. 112, No. 4. (October 2005), pp. 979-999.

Several norms for how people should assess a question's usefulness have been proposed, notably Bayesian diagnosticity, information gain (mutual information), Kullback-Liebler distance, probability gain (error minimization), and impact (absolute change). Several probabilistic models of previous experiments on categorization, covariation assessment, medical diagnosis, and the selection task are shown to not discriminate among these norms as descriptive models of human intuitions and behavior. Computational optimization found situations in which information gain, probability gain, and impact strongly contradict Bayesian diagnosticity. In these situations, diagnosticity's claims are normatively inferior. Results of a new experiment strongly contradict the predictions of Bayesian diagnosticity. Normative theoretical concerns also argue against use of diagnosticity. It is concluded that Bayesian diagnosticity is normatively flawed and empirically unjustified. ((c) 2005 APA, all rights reserved).

Computer simulation of human thought

A Newell — 2008-04-02T01:28:20-00:00

Science, Vol. 134 (1961), pp. 2011-2017.

Computer science as empirical inquiry: symbols and search

Allen Newell — 2007-10-23T22:20:40-00:00

Commun. ACM, Vol. 19, No. 3. (March 1976), pp. 113-126.

Cochlear Implantation for the Treatment of Deafness

Benjamin Copeland — 2008-03-11T22:52:00-00:00

Annual Review of Medicine, Vol. 55, No. 1. (2004), pp. 157-167.

Cochlear implants have dramatically changed the treatment and prognosis for patients with profound sensorineural hearing loss. Deaf adults and children can be successfully (re)integrated into the hearing world through a multidisciplinary approach involving otolaryngologists, audiologists, and speech/language pathologists. As the technology of the cochlear prosthesis advances, the candidacy for these devices continues to broaden. This review addresses the basic technology, candidacy criteria, and important issues in the fields of adult and pediatric cochlear implantation. Cost utility and future directions in the treatment of the profoundly hearing impaired are discussed.

Evidence that cochlear-implanted deaf patients are better multisensory integrators.

J Rouger — 2007-04-04T15:24:33-00:00

Proc Natl Acad Sci U S A (2 April 2007)

The cochlear implant (CI) is a neuroprosthesis that allows profoundly deaf patients to recover speech intelligibility. This recovery goes through long-term adaptative processes to build coherent percepts from the coarse information delivered by the implant. Here we analyzed the longitudinal postimplantation evolution of word recognition in a large sample of CI users in unisensory (visual or auditory) and bisensory (visuoauditory) conditions. We found that, despite considerable recovery of auditory performance during the first year postimplantation, CI patients maintain a much higher level of word recognition in speechreading conditions compared with normally hearing subjects, even several years after implantation. Consequently, we show that CI users present higher visuoauditory performance when compared with normally hearing subjects with similar auditory stimuli. This better performance is not only due to greater speechreading performance, but, most importantly, also due to a greater capacity to integrate visual input with the distorted speech signal. Our results suggest that these behavioral changes in CI users might be mediated by a reorganization of the cortical network involved in speech recognition that favors a more specific involvement of visual areas. Furthermore, they provide crucial indications to guide the rehabilitation of CI patients by using visually oriented therapeutic strategies.

Emergence of rhythm during motor learning.

K Sakai — 2006-06-22T21:12:00-00:00

Trends Cogn Sci, Vol. 8, No. 12. (December 2004), pp. 547-553.

Complex motor skill often consists of a fixed sequence of movements. Recent studies show that a stereotyped temporal pattern or rhythm emerges as we learn to perform a motor sequence. This is because the sequence is reorganized during learning as serial chunks of movements in both a sequence-specific and subject-specific manner. On the basis of human imaging studies we propose that the formation of chunk patterns is controlled by the cerebellum, its posterior and anterior lobes contributing, respectively, to the temporal patterns before and after chunk formation. The motor rhythm can assist the motor networks in the cerebral cortex to control automatic movements within chunks and the cognitive networks to control non-automatic movements between chunks, respectively. In this way, organized motor skill can be performed automatically and flexibly.

Large-scale model of mammalian thalamocortical systems

Eugene Izhikevich — 2008-02-28T20:15:52-00:00

Proceedings of the National Academy of Sciences (21 February 2008), 0712231105.

The understanding of the structural and dynamic complexity of mammalian brains is greatly facilitated by computer simulations. We present here a detailed large-scale thalamocortical model based on experimental measures in several mammalian species. The model spans three anatomical scales. (i) It is based on global (white-matter) thalamocortical anatomy obtained by means of diffusion tensor imaging (DTI) of a human brain. (ii) It includes multiple thalamic nuclei and six-layered cortical microcircuitry based on in vitro labeling and three-dimensional reconstruction of single neurons of cat visual cortex. (iii) It has 22 basic types of neurons with appropriate laminar distribution of their branching dendritic trees. The model simulates one million multicompartmental spiking neurons calibrated to reproduce known types of responses recorded in vitro in rats. It has almost half a billion synapses with appropriate receptor kinetics, short-term plasticity, and long-term dendritic spike-timing-dependent synaptic plasticity (dendritic STDP). The model exhibits behavioral regimes of normal brain activity that were not explicitly built-in but emerged spontaneously as the result of interactions among anatomical and dynamic processes. We describe spontaneous activity, sensitivity to changes in individual neurons, emergence of waves and rhythms, and functional connectivity on different scales. 10.1073/pnas.0712231105

Neuron types in the rat lateral superior olive and developmental changes in the complexity of their dendritic arbors

Heike-Jana Rietzel — 2008-02-28T19:22:11-00:00

The Journal of Comparative Neurology, Vol. 390, No. 1. (1998), pp. 20-40.

The lateral superior olive (LSO), a conspicuous mammalian brainstem nucleus that is involved in sound localization, has become a model system for investigating the formation of topographically organized inhibitory and excitatory connections. In experiments employing intracellular injections of Lucifer yellow or neurobiotin into lightly fixed brain slices, we have examined the soma-dendritic morphology of 483 LSO neurons of rats between postnatal day (P) 4 and P36. A detailed analysis of the shape and complexity of dendritic arbors was performed in 238 neurons in order to identify different cell classes and to determine whether age-related changes occur that may relate to a topographical refinement. Regardless of age, seven classes of LSO neurons were identified, more than had been delineated previously with the Golgi technique. Bipolar neurons and multipolar neurons comprised the two major cell types, whereas small multipolar cells, banana-like cells, bushy cells, unipolar cells, and marginal cells were found less frequently. Age-related changes were analyzed in bipolar and multipolar neurons, and several modifications of their dendritic arbors were observed that are in accordance with a refinement of topography. For example, at P4, bipolar and multipolar cells had relatively broad dendritic arbors, with an average of 140 and 138 dendritic end branches, respectively. During further development, their numbers became drastically reduced by about 80%, such that an average of less than 30 endpoints remained by P36. As the dendritic arbors became smaller specifically along the transverse axis of the LSO, they became confined to a smaller frequency area. We conclude from our results that considerable remodeling takes place in the LSO and that the selective loss of dendritic branches may be a morphological correlate for the formation of exquisite tonotopy. J. Comp. Neurol. 390:20-40, 1998. © 1998 Wiley-Liss, Inc.

Learning in Spiking Neural Networks by Reinforcement of Stochastic Synaptic Transmission

Sebastian Seung — 2006-10-05T12:48:49-00:00

Neuron, Vol. 40, No. 6. (18 December 2003), pp. 1063-1073.

It is well-known that chemical synaptic transmission is an unreliable process, but the function of such unreliability remains unclear. Here I consider the hypothesis that the randomness of synaptic transmission is harnessed by the brain for learning, in analogy to the way that genetic mutation is utilized by Darwinian evolution. This is possible if synapses are "hedonistic," responding to a global reward signal by increasing their probabilities of vesicle release or failure, depending on which action immediately preceded reward. Hedonistic synapses learn by computing a stochastic approximation to the gradient of the average reward. They are compatible with synaptic dynamics such as short-term facilitation and depression and with the intricacies of dendritic integration and action potential generation. A network of hedonistic synapses can be trained to perform a desired computation by administering reward appropriately, as illustrated here through numerical simulations of integrate-and-fire model neurons.

The basal ganglia: learning new tricks and loving it.

AM Graybiel — 2006-02-06T19:49:44-00:00

Curr Opin Neurobiol, Vol. 15, No. 6. (December 2005), pp. 638-644.

The field of basal ganglia research is exploding on every level - from discoveries at the molecular level to those based on human brain imaging. A remarkable series of new findings support the view that the basal ganglia are essential for some forms of learning-related plasticity. Other new findings are challenging some of the basic tenets of the field as it now stands. Combined with the new evidence on learning-related functions of the basal ganglia, these studies suggest that the basal ganglia are parts of a brain-wide set of adaptive neural systems promoting optimal motor and cognitive control.

Elimination and strengthening of glycinergic/GABAergic connections during tonotopic map formation

Gunsoo Kim — 2008-02-25T19:28:02-00:00

Nat Neurosci, Vol. 6, No. 3. (March 2003), pp. 282-290.

Experience-dependent refinement of inhibitory inputs to auditory coincidence-detector neurons

Christoph Kapfer — 2008-02-20T18:52:04-00:00

Nat Neurosci, Vol. 5, No. 3. (March 2002), pp. 247-253.

Development and influence of inhibition in the lateral superior olivary nucleus

Dan Sanes — 2008-02-19T18:37:13-00:00

Hearing Research, Vol. 147, No. 1-2. (September 2000), pp. 46-58.

While studies of neuronal development and plasticity have focused on excitatory pathways, the inhibitory projection from the MNTB to the LSO provides a favorable model for studies of synaptic inhibition. This review covers recent studies from our laboratories indicating that inhibitory connections are quite dynamic during development. These findings suggest that there are two phases inhibitory transmission. During an initial depolarizing phase is growth and branching of pre- and postsynaptic elements in the LSO. During a second hyperpolarizing phase there is refinement of inhibitory afferent arborizations and the LSO dendrites that they innervate.

Path integration and the neural basis of the 'cognitive map'

Bruce Mcnaughton — 2006-07-21T19:08:00-00:00

Nature Reviews Neuroscience, Vol. 7, No. 8., pp. 663-678.

Sound localization by human listeners.

JC Middlebrooks — 2007-10-26T11:01:41-00:00

Annu Rev Psychol, Vol. 42 (1991), pp. 135-159.

In keeping with our promise earlier in this review, we summarize here the process by which we believe spatial cues are used for localizing a sound source in a free-field listening situation. We believe it entails two parallel processes: 1. The azimuth of the source is determined using differences in interaural time or interaural intensity, whichever is present. Wightman and colleagues (1989) believe the low-frequency temporal information is dominant if both are present. 2. The elevation of the source is determined from spectral shape cues. The received sound spectrum, as modified by the pinna, is in effect compared with a stored set of directional transfer functions. These are actually the spectra of a nearly flat source heard at various elevations. The elevation that corresponds to the best-matching transfer function is selected as the locus of the sound. Pinnae are similar enough between people that certain general rules (e.g. Blauert's boosted bands or Butler's covert peaks) can describe this process. Head motion is probably not a critical part of the localization process, except in cases where time permits a very detailed assessment of location, in which case one tries to localize the source by turning the head toward the putative location. Sound localization is only moderately more precise when the listener points directly toward the source. The process is not analogous to localizing a visual source on the fovea of the retina. Thus, head motion provides only a moderate increase in localization accuracy. Finally, current evidence does not support the view that auditory motion perception is anything more than detection of changes in static location over time.

The "ticktock" of our internal clock: direct brain evidence of subjective accents in isochronous sequences

Renaud Brochard — 2007-08-26T09:27:53-00:00

Psychological Science, Vol. 14, No. 4. (2003), pp. 362-366.

The phenomenon commonly known as subjective accenting refers to the fact that identical sound events within purely isochronous sequences are perceived as unequal. Although subjective accenting has been extensively explored using behavioral methods, no physiological evidence has ever been provided for it. In the present study, we tested the notion that these perceived irregularities are related to the dynamic deployment of attention. We disrupted listeners' expectancies in different positions of auditory equitone sequences and measured their responses through brain event-related potentials (ERPs). Significant differences in a late parietal (P3-like) ERP component were found between the responses elicited on odd-numbered versus even-numbered positions, suggesting that a default binary metric structure was perceived. Our findings indicate that this phenomenon has a rather cognitive, attention-dependent origin, partly affected by musical expertise.

Organizing principles of real-time memory encoding: neural clique assemblies and universal neural codes

Longnian Lin — 2006-09-05T08:50:16-00:00

Trends in Neurosciences, Vol. 29, No. 1. (January 2006), pp. 48-57.

Recent identification of network-level coding units, termed neural cliques, in the hippocampus has enabled real-time patterns of memory traces to be mathematically described, directly visualized, and dynamically deciphered. These memory coding units are functionally organized in a categorical and hierarchical manner, suggesting that internal representations of external events in the brain is achieved not by recording exact details of those events, but rather by recreating its own selective pictures based on cognitive importance. This neural-clique-based hierarchical-extraction and parallel-binding process enables the brain to acquire not only large storage capacity but also abstraction and generalization capability. In addition, activation patterns of the neural clique assemblies can be converted to strings of binary codes that would permit universal categorizations of internal brain representations across individuals and species.

A mechanism for cognitive dynamics: neuronal communication through neuronal coherence

Pascal Fries — 2005-09-23T14:12:08-00:00

Trends in Cognitive Sciences, Vol. 9, No. 10. (October 2005), pp. 474-480.

At any one moment, many neuronal groups in our brain are active. Microelectrode recordings have characterized the activation of single neurons and fMRI has unveiled brain-wide activation patterns. Now it is time to understand how the many active neuronal groups interact with each other and how their communication is flexibly modulated to bring about our cognitive dynamics. I hypothesize that neuronal communication is mechanistically subserved by neuronal coherence. Activated neuronal groups oscillate and thereby undergo rhythmic excitability fluctuations that produce temporal windows for communication. Only coherently oscillating neuronal groups can interact effectively, because their communication windows for input and for output are open at the same times. Thus, a flexible pattern of coherence defines a flexible communication structure, which subserves our cognitive flexibility.

Gamma-band activity reflects the metric structure of rhythmic tone sequences.

JS Snyder — 2006-02-09T21:34:36-00:00

Brain Res Cogn Brain Res, Vol. 24, No. 1. (June 2005), pp. 117-126.

Relatively little is known about the dynamics of auditory cortical rhythm processing using non-invasive methods, partly because resolving responses to events in patterns is difficult using long-latency auditory neuroelectric responses. We studied the relationship between short-latency gamma-band (20-60 Hz) activity (GBA) and the structure of rhythmic tone sequences. We show that induced (non-phase-locked) GBA predicts tone onsets and persists when expected tones are omitted. Evoked (phase-locked) GBA occurs in response to tone onsets with approximately 50 ms latency, and is strongly diminished during tone omissions. These properties of auditory GBA correspond with perception of meter in acoustic sequences and provide evidence for the dynamic allocation of attention to temporally structured auditory sequences.

Oscillatory gamma activity in humans and its role in object representation

Catherine Tallon-Baudry — 2006-11-22T10:25:51-00:00

Trends in Cognitive Sciences, Vol. 3, No. 4. (1 April 1999), pp. 151-162.

We experience objects as whole, complete entities irrespective of whether they are perceived by our sensory systems or are recalled from memory. However, it is also known that many of the properties of objects are encoded and processed in different areas of the brain. How then, do coherent representations emerge? One theory suggests that rhythmic synchronization of neural discharges in the gamma band (around 40 Hz) may provide the necessary spatial and temporal links that bind together the processing in different brain areas to build a coherent percept. In this article we propose that this mechanism could also be used more generally for the construction of object representations that are driven by sensory input or internal, top-down processes. The review will focus on the literature on gamma oscillatory activities in humans and will describe the different types of gamma responses and how to analyze them. Converging evidence that suggests that one particular type of gamma activity (induced gamma activity) is observed during the construction of an object representation will be discussed.

Expectancy, Attention, and Time

Ralph Barnes — 2008-02-12T01:20:51-00:00

Cognitive Psychology, Vol. 41, No. 3. (November 2000), pp. 254-311.

Seven experiments examine the influence of contextual timing manipulations on prospective time judgments. Subjects judged durations of standard vs comparison time intervals in the context of a preceding induction (context) sequence. In some experiments, the rate of the induction sequence was systematically manipulated relative to the range of to-be-judged standard time intervals; in others, the induction sequence was omitted. Time judgments were strongly influenced by the rate of an induction sequence with best performance occurring when the standard time interval ended as expected, given context rate. An expectancy profile, in the form of an inverted U, indicated that time estimation accuracy declined systematically as a standard interval differed from a context rate. A similar expectancy profile emerged when the context rate was based on a harmonic subdivision (one-half) of an expected standard interval. Results are discussed in terms of various stimulus-based models of prospective time judgments, including those which appeal to attentional periodicities and entrainment.

Attentional Preparation Based on Temporal Expectancy Modulates Processing at the Perceptual Level

Angel Correa — 2005-06-27T21:17:17-00:00

Psychonomic Bulletin & Review, Vol. 12, No. 2. (April 2005), pp. 328-334.

Neural correlates of rhythmic expectancy

Theodore Zanto — 2008-02-12T00:12:34-00:00

Advances in Cognitive Psychology, Vol. 2 (2006), pp. 221-231.

Temporal expectancy is thought to play a fundamental role in the perception of rhythm. This review summarizes recent studies that investigated rhythmic expectancy by recording neuroelectric activity with high temporal resolution during the presentation of rhythmic patterns. Prior event-related brain potential (ERP) studies have uncovered auditory evoked responses that reflectdetectionofonsets,offsets,sustains,and abrupt changes in acoustic properties such as frequency, intensity, and spectrum, in addition to indexing higher-order processes such as auditory sensory memory and the violation of expectancy. In our studies of rhythmic expectancy, we measured emitted responses – a type of ERP that occurs when an expected event is omitted from a regular series of stimulus events – in simple rhythms with temporal structures typical of music. Our observations suggest that middle-latency gamma band (20-60 Hz) activity (GBA) plays an essential role in auditory rhythm processing. Evoked (phase-locked) GBA occurs in the presence of physically presented auditory events and reflectsthedegreeofaccent.Induced (non-phase-locked) GBA reflectstemporally precise expectancies for strongly and weakly accented events in sound patterns. Thus far, these findingssupporttheoriesofrhythmperception that posit temporal expectancies generated by active neural processes.

The Dynamics of Attending: How People Track Time-Varying Events

Edward Large — 2008-02-11T22:44:04-00:00

Psychological Review, Vol. 106, No. 1. (1999), pp. 119-159.

Feeling the Beat: Movement Influences Infant Rhythm Perception

Jessica Phillips-Silver — 2006-03-07T00:53:43-00:00

Science, Vol. 308, No. 5727. (3 June 2005), 1430.

We hear the melody in music, but we feel the beat. We demonstrate that the perception of musical rhythm is a multisensory experience in infancy. In particular, movement of the body, by bouncing on every second versus every third beat of an ambiguous auditory rhythm pattern, influences whether that auditory rhythm pattern is encoded in duple form (a march) or in triple form (a waltz). Visual information is not necessary for the effect, indicating that it likely reflects a strong, early-developing interaction between auditory and vestibular information in the human nervous system.

Factors affecting the loudness of modulated sounds

Brian Moore — 2008-02-08T21:51:04-00:00

The Journal of the Acoustical Society of America, Vol. 105, No. 5. (1999), pp. 2757-2772.

Loudness matches were obtained between unmodulated carriers and carriers that were amplitude modulated either periodically (rates between 2 and 32 Hz, modulation sinusoidal either on a linear amplitude scale or on a dB scale; the latter is called dB modulation) or with the envelope of the speech of a single talker. The carrier was a 4-kHz sinusoid, white noise, or speech-shaped noise. Both normally hearing subjects and subjects with cochlear hearing loss were tested. Results were expressed as the root-mean-square (rms) level of the modulated carrier minus the level of the unmodulated carrier at the point of equal loudness. If this difference is positive, this indicates that the modulated carrier has a higher rms level at the point of equal loudness. For normally hearing subjects, the results show: (1) For a 4000-Hz sinusoidal carrier, the difference was slightly positive (averaging about 0.7 dB). There was no significant effect of modulation rate or level over the range 20–80 dB SL. (2) For a speech-shaped noise or white noise carrier, the difference was close to zero, although for large modulation depths it tended to be negative. There was no clear effect of level (over the range 35–75 dB SPL) or modulation rate. For the hearing-impaired subjects, the differences were small, but tended to be slightly negative for both the 4000-Hz carrier and the noise carriers, when the modulation rate was above 2 Hz. Again, there was no clear effect of overall level. However, for dB modulation, the differences became more negative with increasing modulation depth. For modulation rates in the range 4–32 Hz, the results could be fitted reasonably well using the assumption that the loudness of modulated sounds is based on the rms value of the time-varying intensity of the response of the basilar membrane (taking into account the compression that occurs in the normal cochlea). The implications of the results for the fitting of multi-band compression hearing aids and for the design of loudness meters are discussed. ©1999 Acoustical Society of America.

Loudness of dynamic stimuli in acoustic and electric hearing

Chaoying Zhang — 2008-02-08T21:45:45-00:00

The Journal of the Acoustical Society of America, Vol. 102, No. 5. (1997), pp. 2925-2934.

Traditional loudness models have been based on the average energy and the critical band analysis of steady-state sounds. However, most environmental sounds, including speech, are dynamic stimuli, in which the average level [e.g., the root-mean-square (rms) level] does not account for the large temporal fluctuations. The question addressed here was whether two stimuli of the same rms level but different peak levels would produce an equal loudness sensation. A modern adaptive procedure was used to replicate two classic experiments demonstrating that the sensation of "beats" in a two- or three-tone complex resulted in a louder sensation [E. Zwicker and H. Fastl, Psychoacoustics—Facts and Models (Springer-Verlag, Berlin, 1990)]. Two additional experiments were conducted to study exclusively the effects of the temporal envelope on the loudness sensation of dynamic stimuli. Loudness balance was performed by normal-hearing listeners between a white noise and a sinusoidally amplitude-modulated noise in one experiment, and by cochlear implant listeners between two harmonic stimuli of the same magnitude spectra, but different phase spectra, in the other experiment. The results from both experiments showed that, for two stimuli of the same rms level, the stimulus with greater temporal fluctuations sometimes produced a significantly louder sensation, depending on the temporal frequency and overall stimulus level. In normal-hearing listeners, the louder sensation was produced for the amplitude-modulated stimuli with modulation frequencies lower than 400 Hz, and gradually disappeared above 400 Hz, resulting in a low-pass filtering characteristic which bore some similarity to the temporal modulation transfer function. The extent to which loudness was greater was a nonmonotonic function of level in acoustic hearing and a monotonically increasingly function in electric hearing. These results suggest that the loudness sensation of a dynamic stimulus is not limited to a 100-ms temporal integration process, and may be determined jointly by a compression process in the cochlea and an expansion process in the brain. A level-dependent compression scheme that may better restore normal loudness of dynamic stimuli in hearing aids and cochlear implants is proposed. ©1997 Acoustical Society of America.

Swinging in the brain: shared neural substrates for behaviors related to sequencing and music

Petr Janata — 2008-02-08T01:02:50-00:00

Nat Neurosci, Vol. 6, No. 7. (July 2003), pp. 682-687.

Auditory cortical plasticity: a comparison with other sensory systems.

JP Rauschecker — 2008-02-06T01:09:40-00:00

Trends Neurosci, Vol. 22, No. 2. (February 1999), pp. 74-80.

The auditory cortex has a crucial role in higher cognitive functions, including the perception of speech, music and auditory space. Cortical plasticity, as in other sensory systems, is used in the fine tuning of the auditory system for these higher functions. Auditory cortical plasticity can also be demonstrated after lesions of the cochlea and it appears to participate in generating tinnitus. Early musical training leads to an expansion in the representation of complex harmonic sounds in the auditory cortex. Similarly, the early phonetic environment has a strong influence on speech development and, presumably, on the cortical organization of speech. In auditory spatial perception, the spectral cues generated by the head and outer ears vary between individuals and have to be calibrated by learning, which most probably takes place at the cortical level. The neural mechanisms of plasticity are likely to be the same across all cortical regions. It should be useful, therefore, to relate some of the findings and hypotheses about auditory cortical plasticity to previous studies of other sensory systems.

Rhythm and Beat Perception in Motor Areas of the Brain

Jessica Grahn — 2008-02-05T01:22:40-00:00

J. Cogn. Neurosci., Vol. 19, No. 5. (1 May 2007), pp. 893-906.

When we listen to rhythm, we often move spontaneously to the beat. This movement may result from processing of the beat by motor areas. Previous studies have shown that several motor areas respond when attending to rhythms. Here we investigate whether specific motor regions respond to beat in rhythm. We predicted that the basal ganglia and supplementary motor area (SMA) would respond in the presence of a regular beat. To establish what rhythm properties induce a beat, we asked subjects to reproduce different types of rhythmic sequences. Improved reproduction was observed for one rhythm type, which had integer ratio relationships between its intervals and regular perceptual accents. A subsequent functional magnetic resonance imaging study found that these rhythms also elicited higher activity in the basal ganglia and SMA. This finding was consistent across different levels of musical training, although musicians showed activation increases unrelated to rhythm type in the premotor cortex, cerebellum, and SMAs (pre-SMA and SMA). We conclude that, in addition to their role in movement production, the basal ganglia and SMAs may mediate beat perception.

Language, music, syntax and the brain.

AD Patel — 2007-01-04T21:52:06-00:00

Nat Neurosci, Vol. 6, No. 7. (July 2003), pp. 674-681.

The comparative study of music and language is drawing an increasing amount of research interest. Like language, music is a human universal involving perceptually discrete elements organized into hierarchically structured sequences. Music and language can thus serve as foils for each other in the study of brain mechanisms underlying complex sound processing, and comparative research can provide novel insights into the functional and neural architecture of both domains. This review focuses on syntax, using recent neuroimaging data and cognitive theory to propose a specific point of convergence between syntactic processing in language and music. This leads to testable predictions, including the prediction that that syntactic comprehension problems in Broca's aphasia are not selective to language but influence music perception as well.

Could information theory provide an ecological theory of sensory processing?

Joseph Atick — 2008-01-29T03:55:20-00:00

Network, Vol. 3 (1992), pp. 213-251.

Endless minds most beautiful

Barbara Finlay — 2006-12-22T11:40:02-00:00

Developmental Science, Vol. 10, No. 1. (January 2007), pp. 30-34.

Action in development

Von Hofsten — 2006-12-22T11:40:00-00:00

Developmental Science, Vol. 10, No. 1. (January 2007), pp. 54-60.

Epigenomic replication: Linking epigenetics to DNA replication

Adrian Mcnairn — 2008-01-28T23:44:45-00:00

BioEssays, Vol. 25, No. 7. (2003), pp. 647-656.

The information contained within the linear sequence of bases (the genome) must be faithfully replicated in each cell cycle, with a balance of constancy and variation taking place over the course of evolution. Recently, it has become clear that additional information important for genetic regulation is contained within the chromatin proteins associated with DNA (the epigenome). Epigenetic information also must be faithfully duplicated in each cell cycle, with a balance of constancy and variation taking place during the course of development to achieve differentiation while maintaining identity within cell lineages. Both the genome and the epigenome are synthesized at the replication fork, so the events occurring during S-phase provide a critical window of opportunity for eliciting change or maintaining existing genetic states. Cells discriminate between different states of chromatin through the activities of proteins that selectively modify the structure of chromatin. Several recent studies report the localization of certain chromatin modifying proteins to replication forks at specific times during S-phase. Since transcriptionally active and inactive chromosome domains generally replicate at different times during S-phase, this spatiotemporal regulation of chromatin assembly proteins may be an integral part of epigenetic inheritance. BioEssays 25:647-656, 2003. © 2003 Wiley Periodicals, Inc.

Audiovisual mirror neurons and action recognition

C Keysers — 2008-01-23T00:15:22-00:00

Experimental Brain Research, Vol. 153, No. 4. (1 December 2003), pp. 628-636.

Many object-related actions can be recognized both by their sound and by their vision. Here we describe a population of neurons in the ventral premotor cortex of the monkey that discharge both when the animal performs a specific action and when it hears or sees the same action performed by another individual. These 'audiovisual mirror neurons' therefore represent actions independently of whether these actions are performed, heard or seen. The magnitude of auditory and visual responses did not differ significantly in half the neurons. A neurometric analysis revealed that based on the response of these neurons, two actions could be discriminated with 97% accuracy.

Hearing sounds, understanding actions: action representation in mirror neurons.

E Kohler — 2006-09-27T05:35:58-00:00

Science, Vol. 297, No. 5582. (2 August 2002), pp. 846-848.

Many object-related actions can be recognized by their sound. We found neurons in monkey premotor cortex that discharge when the animal performs a specific action and when it hears the related sound. Most of the neurons also discharge when the monkey observes the same action. These audiovisual mirror neurons code actions independently of whether these actions are performed, heard, or seen. This discovery in the monkey homolog of Broca's area might shed light on the origin of language: audiovisual mirror neurons code abstract contents-the meaning of actions-and have the auditory access typical of human language to these contents.

When the brain plays music: auditory-motor interactions in music perception and production

Robert Zatorre — 2007-06-20T15:14:39-00:00

Nat Rev Neurosci, Vol. 8, No. 7. (July 2007), pp. 547-558.

Linking Cortical Spike Pattern Codes to Auditory Perception.

Kerry M M Walker — 2007-10-18T14:02:16-00:00

J Cogn Neurosci (5 October 2007)

Abstract Neurometric analysis has proven to be a powerful tool for studying links between neural activity and perception, especially in visual and somatosensory cortices, but conventional neurometrics are based on a simplistic rate-coding hypothesis that is clearly at odds with the rich and complex temporal spiking patterns evoked by many natural stimuli. In this study, we investigated the possible relationships between temporal spike pattern codes in the primary auditory cortex (A1) and the perceptual detection of subtle changes in the temporal structure of a natural sound. Using a two-alternative forced-choice oddity task, we measured the ability of human listeners to detect local time reversals in a marmoset twitter call. We also recorded responses of neurons in A1 of anesthetized and awake ferrets to these stimuli, and analyzed these responses using a novel neurometric approach that is sensitive to temporal discharge patterns. We found that although spike count-based neurometrics were inadequate to account for behavioral performance on this auditory task, neurometrics based on the temporal discharge patterns of populations of A1 units closely matched the psychometric performance curve, but only if the spiking patterns were resolved at temporal resolutions of 20 msec or better. These results demonstrate that neurometric discrimination curves can be calculated for temporal spiking patterns, and they suggest that such an extension of previous spike count-based approaches is likely to be essential for understanding the neural correlates of the perception of stimuli with a complex temporal structure.

Separate Neural Processing of Timbre Dimensions in Auditory Sensory Memory

Anne Caclin — 2007-04-04T14:42:10-00:00

J. Cogn. Neurosci., Vol. 18, No. 12. (1 December 2006), pp. 1959-1972.

Timbre is a multidimensional perceptual attribute of complex tones that characterizes the identity of a sound source. Our study explores the representation in auditory sensory memory of three timbre dimensions (acoustically related to attack time, spectral centroid, and spectrum fine structure), using the mismatch negativity (MMN) component of the auditory event-related potential. MMN is elicited by a discriminable change in a sound sequence and reflects the detection of the discrepancy between the current stimulus and traces in auditory sensory memory. The stimuli used in the present study were carefully controlled synthetic tones. MMNs were recorded after changes along each of the three timbre dimensions and their combinations. Additivity of unidimensional MMNs and dipole modeling results suggest partially separate MMN generators for different timbre dimensions, reflecting their mainly separate processing in auditory sensory memory. The results expand to timbre dimensions a property of separation of the representation in sensory memory that has already been reported between basic perceptual attributes (pitch, loudness, duration, and location) of sound sources.

The evolution of the music faculty: a comparative perspective

Marc Hauser — 2006-07-04T15:33:57-00:00

Nat Neurosci, Vol. 6, No. 7. (July 2003), pp. 663-668.

Oculomotor mechanisms activated by imagery and memory: eye movements to absent objects

Michael Spivey — 2008-01-18T21:31:08-00:00

Psychological Research, Vol. 65, No. 4. (14 November 2001), pp. 235-241.

It is hypothesized that eye movements are used to coordinate elements of a mental model with elements of the visual field. In two experiments, eye movements were recorded while observers imagined or recalled objects that were not present in the visual display. In both cases, observers spontaneously looked at particular blank regions of space in a systematic fashion, to manipulate and organize spatial relationships between mental and/or retinal images. These results contribute to evidence that interpreting a linguistic description of a visual scene requires a spatial (mental model) representation, and they support claims regarding the allocation of position markers in visual space for the manipulation of visual attention. More broadly, our results point to a concrete embodiment of cognition, in that a construction of a mental image is almost "acted out" by the eye movements, and a mental search of internal memory is accompanied by an ocolumotor search of external space.

In praise of tedious anatomy

Joseph Devlin — 2007-10-05T21:08:03-00:00

NeuroImage, Vol. 37, No. 4. (1 October 2007), pp. 1033-1041.

Functional neuroimaging is fundamentally a tool for mapping function to structure, and its success consequently requires neuroanatomical precision and accuracy. Here we review the various means by which functional activation can be localised to neuroanatomy and suggest that the gold standard should be localisation to the individual's or group's own anatomy through the use of neuroanatomical knowledge and atlases of neuroanatomy. While automated means of localisation may be useful, they cannot provide the necessary accuracy, given variability between individuals. We also suggest that the field of functional neuroimaging needs to converge on a common set of methods for reporting functional localisation including a common "standard" space and criteria for what constitutes sufficient evidence to report activation in terms of Brodmann's areas.

The Semantic Conception of Truth: and the Foundations of Semantics

Alfred Tarski — 2008-01-15T20:08:32-00:00

Philosophy and Phenomenological Research, Vol. 4, No. 3. (1944), pp. 341-376.

Deconstructing the gene and reconstructing molecular developmental systems

L Moss — 2008-01-15T20:06:38-00:00

(2001)

A developmental psychobiological systems view: Formulation and current status

G Gotlieb — 2008-01-15T20:04:36-00:00

(2001)

The Century of the Gene

EF Keller — 2008-01-15T20:01:57-00:00

(2000), pp. 66-72.