CiteULike: Author Pine

Multiple Light-Scattering Probes of Foam Structure and Dynamics

DJ Durian — 2007-04-18T19:27:19-00:00

Science, Vol. 252, No. 5006. (3 May 1991), pp. 686-688.

The structure and dynamics of three-dimensional foams are probed quantitatively by exploiting the strong multiple scattering of light that gives foams their familiar white color. Approximating the propagation of light as a diffusion process, transmission measurements provide a direct probe of the average bubble size. A model for dynamic light scattering is developed that can be used to interpret temporal fluctuations in the intensity of multiply scattered light. The results identify previously unrecognized internal dynamics of the foam bubbles. These light-scattering techniques are direct, noninvasive probes of bulk foams and therefore should find wide use in the study of their properties. 10.1126/science.252.5006.686

Microrheology as a tool for high-throughput screening

V Breedveld — 2008-06-28T21:41:05-00:00

Journal of Materials Science, Vol. 38, No. 22. (1 November 2003), pp. 4461-4470.

Microrheology can be used for high-throughput screening of the rheological properties of sample libraries of complex fluids. Two passive techniques are particularly suitable: video microscopy and diffusing-wave spectroscopy. The techniques complement each other very well and can be applied to samples that offer different experimental challenges. We offer a thorough analysis of the strengths and limitations of microrheology with the emphasis on high-throughput applications. To illustrate the potential of microrheology, results are presented for two representative cases: the rheological screening of aqueous solutions of a block copolypeptide library and the rheological phase diagram of a water/surfactant/salt system.

Amygdala and ventrolateral prefrontal cortex activation to masked angry faces in children and adolescents with generalized anxiety disorder.

CS Monk — 2008-06-12T02:42:31-00:00

Archives of general psychiatry, Vol. 65, No. 5. (May 2008), pp. 568-576.

CONTEXT: Vigilance for threat is a key feature of generalized anxiety disorder (GAD). The amygdala and the ventrolateral prefrontal cortex constitute a neural circuit that is responsible for detection of threats. Disturbed interactions between these structures may underlie pediatric anxiety. To date, no study has selectively examined responses to briefly presented threats in GAD or in pediatric anxiety. OBJECTIVE: To investigate amygdala and ventrolateral prefrontal cortex activation during processing of briefly presented threats in pediatric GAD. DESIGN: Case-control study. SETTING: Government clinical research institute. PARTICIPANTS: Youth volunteers, 17 with GAD and 12 without a psychiatric diagnosis. MAIN OUTCOME MEASURES: We used functional magnetic resonance imaging to measure blood oxygenation level-dependent signal. During imaging, subjects performed an attention-orienting task with rapidly presented (17 milliseconds) masked emotional (angry or happy) and neutral faces. RESULTS: When viewing masked angry faces, youth with GAD relative to comparison subjects showed greater right amygdala activation that positively correlated with anxiety disorder severity. Moreover, in a functional connectivity (psychophysiological interaction) analysis, the right amygdala and the right ventrolateral prefrontal cortex showed strong negative coupling specifically to masked angry faces. This negative coupling tended to be weaker in youth with GAD than in comparison subjects. CONCLUSIONS: Youth with GAD have hyperactivation of the amygdala to briefly presented masked threats. The presence of threat-related negative connectivity between the right ventrolateral prefrontal cortex and the amygdala suggests that the prefrontal cortex modulates the amygdala response to threat. In pediatric GAD, amygdala hyperresponse occurs in the absence of a compensatory increase in modulation by the ventrolateral prefrontal cortex.

Contextual Fear Conditioning in Humans: Cortical-Hippocampal and Amygdala Contributions

Ruben Alvarez — 2008-06-11T18:55:45-00:00

J. Neurosci., Vol. 28, No. 24. (11 June 2008), pp. 6211-6219.

Functional imaging studies of cued fear conditioning in humans have mostly confirmed findings in animals, but it is unclear whether the brain mechanisms that underlie contextual fear conditioning in animals are also preserved in humans. We investigated this issue using functional magnetic resonance imaging and virtual reality contexts. Subjects underwent differential context conditioning in which they were repeatedly exposed to two contexts (CXT+ and CXT-) in semirandom order, with contexts counterbalanced across participants. An unsignaled footshock was consistently paired with the CXT+, and no shock was ever delivered in the CXT-. Evidence for context conditioning was established using skin conductance and anxiety ratings. Consistent with animal models centrally implicating the hippocampus and amygdala in a network supporting context conditioning, CXT+ compared with CXT- significantly activated right anterior hippocampus and bilateral amygdala. In addition, context conditioning was associated with activation in posterior orbitofrontal cortex, medial dorsal thalamus, anterior insula, subgenual anterior cingulate, and parahippocampal, inferior frontal, and parietal cortices. Structural equation modeling was used to assess interactions among the core brain regions mediating context conditioning. The derived model indicated that medial amygdala was the source of key efferent and afferent connections including input from orbitofrontal cortex. These results provide evidence that similar brain mechanisms may underlie contextual fear conditioning across species. 10.1523/JNEUROSCI.1246-08.2008

Phase diagrams of nearly-hard-sphere binary colloids

AD Dinsmore — 2008-06-03T04:28:41-00:00

Physical Review E, Vol. 52, No. 4. (1 October 1995), 4045.

Effective parameters for stimulation of dissociated cultures using multi-electrode arrays.

DA Wagenaar — 2005-08-02T02:55:07-00:00

J Neurosci Methods, Vol. 138, No. 1-2. (30 September 2004), pp. 27-37.

Electrical stimulation through multi-electrode arrays is used to evoke activity in dissociated cultures of cortical neurons. We study the efficacies of a variety of pulse shapes under voltage control as well as current control, and determine useful parameter ranges that optimize efficacy while preventing damage through electrochemistry. For any pulse shape, stimulation is found to be mediated by negative currents. We find that positive-then-negative biphasic voltage-controlled pulses are more effective than any of the other pulse shapes tested, when compared at the same peak voltage. These results suggest that voltage-control, with its inherent control over limiting electrochemistry, may be advantageous in a wide variety of stimulation scenarios, possibly extending to in-vivo experiments.

Random organization in periodically driven systems

Laurent Corte — 2008-05-02T18:54:40-00:00

Nat Phys, Vol. 4, No. 5. (May 2008), pp. 420-424.

Is Structure Dependence an Innate Constraint? New Experimental Evidence From Children's Complex-Question Production

Ben Ambridge — 2008-04-30T13:56:49-00:00

Cognitive Science: A Multidisciplinary Journal, Vol. 32, No. 1. (2008), pp. 222-255.

According to Crain and Nakayama (1987), when forming complex yes/no questions, children do not make errors such as Is the boy who smoking is crazy? because they have innate knowledge of structure dependence and so will not move the auxiliary from the relative clause. However, simple recurrent networks are also able to avoid such errors, on the basis of surface distributional properties of the input (Lewis & Elman, 2001; Reali & Christiansen, 2005). Two new elicited production studies revealed that (a) children occasionally produce structure-dependence errors and (b) the pattern of children's auxiliary-doubling errors (Is the boy who is smoking is crazy?) suggests a sensitivity to surface co-occurrence patterns in the input. This article concludes that current data do not provide any support for the claim that structure dependence is an innate constraint, and that it is possible that children form a structure-dependent grammar on the basis of exposure to input that exhibits this property.

Dense Packing and Symmetry in Small Clusters of Microspheres

Vinothan Manoharan — 2007-04-04T07:42:56-00:00

Science, Vol. 301, No. 5632. (25 July 2003), pp. 483-487.

When small numbers of colloidal microspheres are attached to the surfaces of liquid emulsion droplets, removing fluid from the droplets leads to packings of spheres that minimize the second moment of the mass distribution. The structures of the packings range from sphere doublets, triangles, and tetrahedra to exotic polyhedra not found in infinite lattice packings, molecules, or minimum-potential energy clusters. The emulsion system presents a route to produce newcolloidal structures and a means to study howdifferent physical constraints affect symmetry in small parcels of matter. 10.1126/science.1086189

Self-Diffusion of Interacting Colloids Far from Equilibrium

Xia Qiu — 2008-04-26T00:12:25-00:00

Physical Review Letters, Vol. 61, No. 22. (28 November 1988), 2554.

Yielding and Rearrangements in Disordered Emulsions

P Hébraud — 2008-04-25T19:52:15-00:00

Physical Review Letters, Vol. 78, No. 24. (16 June 1997), 4657.

Depressive symptoms during childhood and adult obesity: the Zurich Cohort Study

G Hasler — 2005-04-19T18:12:16-00:00

Molecular Psychiatry, Vol. aop, No. current. (19 April 2005)

Preparation of monodisperse PMMA microspheres in nonpolar solvents by dispersion polymerization with a macromonomeric stabilizer

Sascham Klein — 2007-05-27T21:14:34-00:00

Colloid & Polymer Science, Vol. 282, No. 1. (1 December 2003), pp. 7-13.

We discuss a dispersion polymerization procedure for preparing monodisperse and micron-sized poly(methyl methacrylate) (PMMA) particles in hexanes with methacryloxypropyl-terminated polydimethylsiloxane stabilizers. We investigate the effects of the stabilizer molecular weight, stabilizer concentration, and monomer concentration on the particle size and polydispersity. We find that a minimum molecular weight of 10 000 g/mol is necessary to synthesize colloidally stable PMMA dispersions. The particle polydispersity is minimal (=5%) for stabilizer to monomer weight ratios of 0.02 to 0.1, while PMMA particles prepared under conditions outside this range are polydisperse. The particle diameter can be varied from 0.4 to 1.5 µm by appropriate choices of stabilizer and monomer concentrations. Stable PMMA suspensions can be prepared at up to 26.3% solids. The dispersions are stable in most liquid aliphatics, and are monodisperse enough to form ordered domains at high concentration. This single-stage synthesis, requiring only commercially available materials, may be of interest to those seeking a simple way to prepare highly monodisperse non-aqueous dispersions in the micron size range.

Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles

Andrew Nowak — 2008-02-28T21:40:29-00:00

Nature, Vol. 417, No. 6887. (23 May 2002), pp. 424-428.

Developmental neurotoxicity of ketamine: morphometric confirmation, exposure parameters, and multiple fluorescent labeling of apoptotic neurons.

AC Scallet — 2008-02-20T09:33:21-00:00

Toxicol Sci, Vol. 81, No. 2. (October 2004), pp. 364-370.

Ketamine is a widely used pediatric anesthetic recently reported (C. Ikonomidou et al., 1999, Science 283, 70-74) to enhance neuronal death in neonatal rats. To confirm and extend these results, we treated four groups of PND 7 rats with seven sc doses, one every 90 min, of either saline, 10 mg/kg ketamine, 20 mg/kg ketamine, or a single dose of 20 mg/kg ketamine. The repeated doses of 20 mg/kg ketamine increased the number of silver-positive (degenerating) neurons in the dorsolateral thalamus to a degree comparable to previous results (Ikonomidou et al., 1999, Science 283, 70-74), i.e., 28-fold vs. 31-fold respectively. However, blood levels of ketamine immediately after the repeated 20 mg/kg doses were about 14 micrograms/ml, about seven-fold greater than anesthetic blood levels in humans (J. M. Malinovsky et al., 1996, Br. J. Anaesth. 77, 203-207; R. A. Mueller and R. Hunt, 1998, Pharmacol. Biochem. Behav. 60, 15-22). Levels of ketamine in blood following exposure to the multiple 10 mg/kg doses of ketamine or to a single 20 mg/kg dose ranged around 2-5 micrograms/ml; although these blood levels are close to an anesthetic level in humans, they failed to produce neurodegeneration. To investigate the mode of ketamine-induced neuronal death, coronal sections were stained with both Fluoro-Jade B (a green fluorescent stain selective for neurodegeneration) and DAPI (a blue DNA stain), as well as for caspase-3 (using an antisera labeled red with rhodamine). These histochemical results confirmed the developmental neurotoxicity of ketamine, demonstrated that Fluoro-Jade B (FJ-B), like silver methods, successfully stained degenerating neurons in neonatal rats, and indicated that ketamine acts by increasing the rate of neuronal apoptosis.

Chaos and threshold for irreversibility in sheared suspensions

DJ Pine — 2005-12-14T22:24:06-00:00

Nature, Vol. 438, No. 7070., pp. 997-1000.

Characterization of the effect of sample quality on high density oligonucleotide microarray data using progressively degraded rat liver RNA

Karol Thompson — 2007-09-14T16:38:43-00:00

BMC Biotechnology, Vol. 7 (13 September 2007), 57.

Modulation of emotion by cognition and cognition by emotion

KS Blair — 2007-05-17T08:25:40-00:00

NeuroImage, Vol. 35, No. 1. (March 2007), pp. 430-440.

In this study, we examined the impact of goal-directed processing on the response to emotional pictures and the impact of emotional pictures on goal-directed processing. Subjects (N = 22) viewed neutral or emotional pictures in the presence or absence of a demanding cognitive task. Goal-directed processing disrupted the BOLD response to emotional pictures. In particular, the BOLD response within bilateral amygdala and inferior frontal gyrus decreased during concurrent task performance. Moreover, the presence of both positive and negative distractors disrupted task performance, with reaction times increasing for emotional relative to neutral distractors. Moreover, in line with the suggestion of the importance of lateral frontal regions in emotional regulation [Ochsner, K. N., Ray, R. D., Cooper, J. C., Robertson, E. R., Chopra, S., Gabrieli, J. D., et al. (2004). For better or for worse: neural systems supporting the cognitive down-and up-regulation of negative emotion. NeuroImage, 23(2), 483-499], connectivity analysis revealed positive connectivity between lateral superior frontal cortex and regions of middle frontal cortex previously implicated in emotional suppression [Beauregard, M., Levesque, J., and Bourgouin, P. (2001). Neural correlates of conscious self-regulation of emotion. J. Neurosci., 21 (18), RC165.; Levesque, J., Eugene, F., Joanette, Y., Paquette, V., Mensour, B., Beaudoin, G., et al. (2003). Neural circuitry underlying voluntary suppression of sadness. Biol. Psychiatry, 53 (6), 502-510.; Ohira, H., Nomura, M., Ichikawa, N., Isowa, T., Iidaka, T., Sato, A., et al. (2006). Association of neural and physiological responses during voluntary emotion suppression. NeuroImage, 29 (3), 721-733] and negative connectivity with bilateral amygdala. These data suggest that processes involved in emotional regulation are recruited during task performance in the context of emotional distractors.

Linking working memory and long-term memory: a computational model of the learning of new words

Jones — 2007-10-31T06:48:56-00:00

Developmental Science, Vol. 10, No. 6. (November 2007), pp. 853-873.

Essential Logic: Basic Reasoning Skills for the Twenty-First Century

Ronald Pine — 2007-12-05T05:42:05-00:00

(15 June 2002)

Essential Logic offers: BL Readability. A dialogue-like yet challenging style makes this introductory logic textbook engaging and interesting. BL Essentials. Deductive and inductive reasoning, formal and informal logic are placed within a philosophical perspective. BL Rigor. A careful sequence of learning steps communicates the essential skills of reasoning and directs students to write, support, and argue by connecting criticism to key concepts. BL Relevance. Explanations and examples take students' lives into consideration and are designed for students with diverse backgrounds and a wide range of experiences. BL A Theme. Traditional concepts are integrated with a discussion of modern technological issues and the world view of modern science. A unique chapter on Logic and Hope addresses questions students often ask and suggests a global perspective. BL Controversy. Students are encouraged to defend and critique positions--including those presented by the author. A unique final chapter on Fuzzy Logic is framed as a debate between Western and Eastern philosophy. BL Exercises. Students gain confidence in recognizing arguments, structuring them into premises and conclusions, identifying and critiquing informal fallacies, while learning to create, follow, and appreciate symbolic reasoning trails. BL Coverage. Chapters cover Argument Recognition and Language Analysis, Inductive Reasoning, Structuring Informal Fallacies, Symbolic Translation, Truth Tables, Formal Proofs of Validity, Quantification, and the basics of Fuzzy Set Theory and Propositional Logic.

Developmental differences in neuronal engagement during implicit encoding of emotional faces: an event-related fMRI study.

EE Nelson — 2007-05-12T04:48:43-00:00

J Child Psychol Psychiatry, Vol. 44, No. 7. (October 2003), pp. 1015-1024.

BACKGROUND: Prior studies document strong interactions between emotional and mnemonic processes. These interactions have been shown to vary across development and psychopathology, particularly mood and anxiety disorders. METHODS: The present study used functional neuroimaging to assess the degree to which adolescents and adults differ in patterns of neuronal engagement during implicit encoding of affective stimuli. Subjects underwent rapid event-related fMRI while viewing faces with angry, fearful, happy, and neutral expressions. A surprise post-scan memory test was administered. RESULTS: Consistent with previous findings, both adolescents and adults displayed engagement of left ventrolateral prefrontal cortex when viewing subsequently recognized stimuli. Age differences emerged in patterns of neuronal activation associated with subsequent recognition of specific face-emotion types. Relative to adults, adolescents displayed more activity in the anterior cingulate when viewing subsequently remembered angry faces, and more activity in the right temporal pole when viewing subsequently remembered fear faces. Conversely, adults displayed more activity in the subgenual anterior cingulate when viewing subsequently remembered happy faces and more activity in the right posterior hippocampus when viewing subsequently remembered neutral faces. These age-related differences emerged in the absence of differences in behavioral performance. CONCLUSIONS: These findings document developmental differences in the degree to which engagement of affective circuitry contributes to memory formation.

Attention Bias to Threat in Maltreated Children: Implications for Vulnerability to Stress-Related Psychopathology

Daniel Pine — 2007-11-29T16:25:34-00:00

Am J Psychiatry, Vol. 162, No. 2. (1 February 2005), pp. 291-296.

OBJECTIVE: Previous research in adults implicates attention bias in posttraumatic stress disorder (PTSD). To study attention bias in children, the authors used picture-based versions of the visual-probe attention bias task previously used with adults. They tested the hypothesis that attention bias to threatening facial photographs is associated with maltreatment and PTSD. METHOD: A visual-probe task that manipulated threat levels was used to test 34 children who had been maltreated and 21 children who had not been maltreated. The visual-probe task involved showing photographs of actors with faces depicting neutral, angry/threatening, or happy expressions for 500 msec each. RESULTS: Attention bias away from threat was associated with severity of physical abuse and diagnosis of PTSD. This association reflected the tendency for high levels of abuse or PTSD to predict attention avoidance of threatening faces. CONCLUSIONS: Previous studies examined the engagement of specific brain regions associated with attention orientation to angry/threatening faces. The current study used similar methods to document associations between attention bias and maltreatment in children. This sets the stage for studies examining relationships in children among perturbed brain function, psychopathology, attention bias, and maltreatment. 10.1176/appi.ajp.162.2.291

Colloidal Clusters of Silica or Polymer Microspheres

G-R Yi — 2007-05-27T21:16:49-00:00

Advanced Materials, Vol. 16, No. 14. (2004), pp. 1204-1208.

No abstract.

Effects of cryptic mortality and the hidden costs of using length limits in fishery management

Coggins — 2007-08-22T07:29:34-00:00

Fish and Fisheries, Vol. 8, No. 3. (September 2007), pp. 196-210.

Performance on a Virtual Reality Spatial Memory Navigation Task in Depressed Patients

Neda Gould — 2007-08-27T13:29:50-00:00

Am J Psychiatry, Vol. 164, No. 3. (1 March 2007), pp. 516-519.

OBJECTIVE: Findings on spatial memory in depression have been inconsistent. A navigation task based on virtual reality may provide a more sensitive and consistent measure of the hippocampal-related spatial memory deficits associated with depression. METHOD: Performance on a novel virtual reality navigation task and a traditional measure of spatial memory was assessed in 30 depressed patients (unipolar and bipolar) and 19 normal comparison subjects. RESULTS: Depressed patients performed significantly worse than comparison subjects on the virtual reality task, as assessed by the number of locations found in the virtual town. Between-group differences were not detected on the traditional measure. The navigation task showed high test-retest reliability. CONCLUSIONS: Depressed patients performed worse than healthy subjects on a novel spatial memory task. Virtual reality navigation may provide a consistent, sensitive measure of cognitive deficits in patients with affective disorders, representing a mechanism to study a putative endophenotype for hippocampal function. 10.1176/appi.ajp.164.3.516

Parental diagnoses in youth with narrow phenotype bipolar disorder or severe mood dysregulation.

MA Brotman — 2007-08-05T15:50:00-00:00

Am J Psychiatry, Vol. 164, No. 8. (August 2007), pp. 1238-1241.

OBJECTIVE: Controversy exists regarding whether nonepisodic irritability and hyperarousal (severe mood dysregulation) is a phenotype of pediatric bipolar disorder. The authors compared axis I diagnoses in parents of children with narrow phenotype bipolar disorder and parents of youth with severe mood dysregulation. METHOD: Parents of youth with narrow phenotype bipolar disorder (proband N=33, parent N=42) and youth with severe mood dysregulation (proband N=30, parent N=37) were interviewed by clinicians who were blind to the child's diagnostic status using the Diagnostic Interview for Genetic Studies. RESULTS: Compared to parents of youth with severe mood dysregulation, parents of youth with narrow phenotype bipolar disorder were significantly more likely to be diagnosed with bipolar disorder. There were no other diagnostic differences between the two groups. CONCLUSIONS: These data suggest that narrow phenotype bipolar disorder may be distinct from severe mood dysregulation in terms of familial aggregation. Additionally, the familiality of narrow phenotype bipolar disorder and adult DSM-IV bipolar disorder is high.

Elastic Electron-Proton Scattering at Large Four-Momentum Transfer

PN Kirk — 2007-08-05T22:36:41-00:00

Physical Review D, Vol. 8, No. 1. (1 July 1973), 63.

Electron-proton elastic-scattering cross sections have been measured at the Stanford Linear Accelerator Center for four-momentum transfers squared q 2 from 1.0 to 25.0 (GeV / c ) 2 . The electric ( G E p ) and magnetic ( G M p ) form factors of the proton were not separated; since angular distributions were not measured at each q 2 . However; values for G M p were derived assuming various relations between G E p and G M p . Several theoretical models for the behavior of the proton magnetic form factor at high values of q 2 are compared with the data.

The effects of prohibiting gestures on children's lexical retrieval ability

Karen Pine — 2007-07-23T19:32:35-00:00

Developmental Science, Vol. 0, No. 0. (0000), pp. ???-???.

Abstract Two alternative accounts have been proposed to explain the role of gestures in thinking and speaking. The Information Packaging Hypothesis (Kita, 2000) claims that gestures are important for the conceptual packaging of information before it is coded into a linguistic form for speech. The Lexical Retrieval Hypothesis (Rauscher, Krauss & Chen, 1996) sees gestures as functioning more at the level of speech production in helping the speaker to find the right words. The latter hypothesis has not been fully explored with children. In this study children were given a naming task under conditions that allowed and restricted gestures. Children named more words correctly and resolved more tip-of-the-tongue states when allowed to gesture than when not, suggesting that gestures facilitate access to the lexicon in children and are important for speech production as well as conceptualization.

Preparation of Doublet, Triangular, and Tetrahedral Colloidal Clusters by Controlled Emulsification

D Zerrouki — 2007-06-14T03:52:26-00:00

Langmuir, Vol. 22, No. 1. (3 January 2006), pp. 57-62.

Abstract: We describe a six-step method for making colloidal clusters of 2, 3, or 4 silica particles with a radius of 1.2 m. This method, originally described by Manoharan et al. (Manoharan, V. N.; Elsesser, M. T.; Pine, D. J. Science 2003, 301, 483), is based on the encapsulation of silica spheres in emulsion droplets. The originality of our work lies in the preparation of monodisperse emulsions, which allows us to obtain some high yields of small aggregates over a wide range of conditions. Using optical microscopy and disk centrifugation, we show that the relative fractions of 2, 3, and 4 particle aggregates are controlled by the emulsification conditions, particularly the concentration of silica in the dispersed phase. Our best yields are obtained using low to moderate shear rates, a highly viscous continuous phase, and intermediate amounts of silica. The sedimentation of the colloidal solution into a gradient of concentration leads to aqueous suspensions of identical clusters. Since the overall process can easily be scaled up, large quantities of identical clusters may be prepared, which should allow the thermodynamic properties of these new colloidal objects to be measured for the first time. These nonspherical particles could serve as building blocks for more complex assemblies, such as colloidal crystals which could find applications as photonic materials.

fMRI predictors of treatment outcome in pediatric anxiety disorders

Mcclure — 2007-03-14T10:13:13-00:00

Psychopharmacology, Vol. 191, No. 1. (March 2007), pp. 97-105.

Reduction of Trace but Not Delay Eyeblink Conditioning in Panic Disorder

Christian Grillon — 2007-05-23T19:44:51-00:00

Am J Psychiatry, Vol. 164, No. 2. (1 February 2007), pp. 283-289.

OBJECTIVE: Individuals with panic disorder perceive panic attacks as unpredictable. Because predictability is fundamental to Pavlovian conditioning, failure to predict panic attacks could be due to a basic deficit in conditioning. The present study examined trace eyeblink conditioning in order to test the hypothesis that individuals with panic disorder are impaired in associative learning tasks that depend on declarative memory. METHOD: Delay and trace eyeblink conditioning were tested in separate experimental sessions in 19 individuals meeting DSM-IV criteria for panic disorder and 19 sex- and age-matched healthy comparison subjects. In the delay paradigm, a mild puff was delivered to the eye at the end of a 500-msec tone; in the trace paradigm, the puff was delivered after a 700-msec empty "trace" interval that followed the end of the tone. RESULTS: Patients and comparison subjects showed similar rates of conditioned responses in the delay paradigm, but patients showed reduced rates of conditioned responses in the trace paradigm. CONCLUSIONS: These results suggest that individuals with panic disorder suffer from a deficit in declarative associative learning. Such a deficit points to impaired hippocampal function that may disrupt cognitive processing of internal and external cues predictive of a panic attack. 10.1176/appi.ajp.164.2.283

The Impact of Tryptophan Depletion and 5-HTTLPR Genotype on Passive Avoidance and Response Reversal Instrumental Learning Tasks

Elizabeth Finger — 2006-08-18T05:15:35-00:00

Neuropsychopharmacology, Vol. aop, No. current.

The impact of processing load on emotion.

DG Mitchell — 2007-05-18T04:33:19-00:00

Neuroimage, Vol. 34, No. 3. (1 February 2007), pp. 1299-1309.

This event-related fMRI study examined the impact of processing load on the BOLD response to emotional expressions. Participants were presented with composite stimuli consisting of neutral and fearful faces upon which semi-transparent words were superimposed. This manipulation held stimulus-driven features constant across multiple levels of processing load. Participants made either (1) gender discriminations based on the face; (2) case judgments based on the words; or (3) syllable number judgments based on the words. A significant main effect for processing load was revealed in prefrontal cortex, parietal cortex, visual processing areas, and amygdala. Critically, enhanced activity in the amygdala and medial prefrontal cortex seen during gender discriminations was significantly reduced during the linguistic task conditions. A connectivity analysis conducted to investigate theories of cognitive modulation of emotion showed that activity in dorsolateral prefrontal cortex was inversely related to activity in the ventromedial prefrontal cortex. Together, the data suggest that the processing of task-irrelevant emotional information, like neutral information, is subject to the effects of processing load and is under top-down control.

Cortical brain regions engaged by masked emotional faces in adolescents and adults: an fMRI study.

DS Pine — 2007-05-16T10:53:52-00:00

Emotion, Vol. 1, No. 2. (June 2001), pp. 137-147.

Face-emotion processing has shown signs of developmental change during adolescence. Functional magnetic resonance imaging (fMRI) was used on 10 adolescents and 10 adults to contrast brain regions engaged by a masked emotional-face task (viewing a fixation cross and a series of masked happy and masked fearful faces), while blood oxygen level dependent signal was monitored by a 1.5-T MRI scanner. Brain regions differentially engaged in the 2 age groups were mapped by using statistical parametric mapping. Summed across groups, the contrast of masked face versus fixation-cross viewing generated activations in occipital-temporal regions previously activated in passive face-viewing tasks. Adolescents showed higher maxima for activations in posterior association cortex for 3 of the 4 statistical contrasts. Adolescents and adults differed in the degree to which posterior hemisphere brain areas were engaged by viewing masked facial displays of emotion.

Ventrolateral prefrontal cortex activation and attentional bias in response to angry faces in adolescents with generalized anxiety disorder.

CS Monk — 2006-09-19T22:21:18-00:00

Am J Psychiatry, Vol. 163, No. 6. (June 2006), pp. 1091-1097.

OBJECTIVE: While adolescent anxiety disorders represent prevalent, debilitating conditions, few studies have explored their brain physiology. Using event-related functional magnetic resonance imaging (fMRI) and a behavioral measure of attention to angry faces, the authors evaluated differences in response between healthy adolescents and adolescents with generalized anxiety disorder. METHOD: In the primary trials of interest, 18 adolescents with generalized anxiety disorder and 15 comparison subjects of equivalent age/gender/IQ viewed angry/neutral face pairs during fMRI acquisition. Following the presentation of each face pair, subjects pressed a button to indicate whether a subsequent asterisk appeared on the same (congruent) or opposite (incongruent) side as the angry face. Reaction time differences between congruent and incongruent face trials provided a measure of attention bias to angry faces. RESULTS: Relative to the comparison subjects, patients with generalized anxiety disorder manifested greater right ventrolateral prefrontal cortex activation to trials containing angry faces. Patients with generalized anxiety disorder also showed greater attention bias away from angry faces. Ventrolateral prefrontal cortex activation differences remained evident when differences in attention bias were covaried. Finally, in an examination among patients of the association between degree of anxiety and brain activation, the authors found that as ventrolateral prefrontal cortex activation increased, severity of anxiety symptoms diminished. CONCLUSIONS: Adolescents with generalized anxiety disorder show greater right ventrolateral prefrontal cortex activation and attentional bias away from angry faces than healthy adolescents. Among patients, increased ventrolateral prefrontal cortex activation is associated with less severe anxiety, suggesting that this activation may serve as a compensatory response.

Emotion recognition deficits in pediatric anxiety disorders: implications for amygdala research.

J Easter — 2007-05-12T04:30:35-00:00

J Child Adolesc Psychopharmacol, Vol. 15, No. 4. (August 2005), pp. 563-570.

INTRODUCTION: Anxiety disorders in adults involve aberrant processing of emotional information that is hypothesized to reflect perturbations in the amygdala. This study examines the relationship between face-emotion recognition and anxiety in a sample of children and adolescents participating in a brain-imaging study of amygdala structure and function. METHODS: This study recruited 15 children and adolescents with ongoing anxiety disorders and 11 psychiatrically healthy comparisons group-matched on age, gender, and IQ. Face-emotion recognition was assessed using the Diagnostic Analysis of Nonverbal Accuracy Scale (DANVA). RESULTS: Children and adolescents with anxiety disorders exhibited significantly poorer performance on the face-emotion recognition task compared to healthy controls (z = 2.2; p < 0.05). This difference was found only for expressions posed by adults but not children. Discussion: Reduced accuracy on a face-emotion recognition test is consistent with perturbed amygdala function in pediatric anxiety disorders. CONCLUSION: As this study was conducted in a sample undergoing a neuroimaging investigation of amygdala integrity, future analyses will examine associations among amygdala function, clinical anxiety, and face-recognition abilities.

Affective neuroscience and the development of social anxiety disorder.

DS Pine — 2007-05-12T04:13:50-00:00

Psychiatr Clin North Am, Vol. 24, No. 4. (December 2001), pp. 689-705.

Recent studies on the familial distribution and longitudinal outcome of SAD emphasize developmental aspects of the syndrome, consistent with the developmental psychopathology perspective. Key questions in this area concern factors that mediate familial transmission and that predict outcome. Prior studies provide incomplete answers to these questions. Recent studies in affective neuroscience suggest potential avenues for answering these questions. As reviewed in the current article, fMRI studies of face processing provide examples of such potentially informative research directions.

Abnormal attention modulation of fear circuit function in pediatric generalized anxiety disorder.

EB McClure — 2007-05-10T11:07:04-00:00

Arch Gen Psychiatry, Vol. 64, No. 1. (January 2007), pp. 97-106.

CONTEXT: Considerable work implicates abnormal neural activation and disrupted attention to facial-threat cues in adult anxiety disorders. However, in pediatric anxiety, no research has examined attention modulation of neural response to threat cues. OBJECTIVE: To determine whether attention modulates amygdala and cortical responses to facial-threat cues differentially in adolescents with generalized anxiety disorder and in healthy adolescents. DESIGN: Case-control study. SETTING: Government clinical research institute. PARTICIPANTS: Fifteen adolescents with generalized anxiety disorder and 20 controls. MAIN OUTCOME MEASURES: Blood oxygenation level-dependent signal as measured via functional magnetic resonance imaging. During imaging, participants completed a face-emotion rating task that systematically manipulated attention. RESULTS: While attending to their own subjective fear, patients, but not controls, showed greater activation to fearful faces than to happy faces in a distributed network including the amygdala, ventral prefrontal cortex, and anterior cingulate cortex (P<.05, small-volume corrected, for all). Right amygdala findings appeared particularly strong. Functional connectivity analyses demonstrated positive correlations among the amygdala, ventral prefrontal cortex, and anterior cingulate cortex. CONCLUSIONS: This is the first evidence in juveniles that generalized anxiety disorder-associated patterns of pathologic fear circuit activation are particularly evident during certain attention states. Specifically, fear circuit hyperactivation occurred in an attention state involving focus on subjectively experienced fear. These findings underscore the importance of attention and its interaction with emotion in shaping the function of the adolescent human fear circuit.

Multiple Light-Scattering Probes of Foam Structure and Dynamics

DJ Durian — 2007-04-18T19:28:43-00:00

The structure and dynamics of three-dimensional foams are probed quantitatively by exploiting the strong multiple scattering of light that gives foams their familiar white color. Approximating the propagation of light as a diffusion process, transmission measurements provide a direct probe of the average bubble size. A model for dynamic light scattering is developed that can be used to interpret temporal fluctuations in the intensity of multiply scattered light. The results identify previously unrecognized internal dynamics of the foam bubbles. These light-scattering techniques are direct, noninvasive probes of bulk foams and therefore should find wide use in the study of their properties.

The design and analysis of field studies to estimate catch-and-release mortality

KH Pollock — 2007-03-20T11:22:16-00:00

Fisheries Management & Ecology, Vol. 14, No. 2. (April 2007), pp. 123-130.

Neural substrates of choice selection in adults and adolescents: Development of the ventrolateral prefrontal and anterior cingulate cortices.

N Eshel — 2007-03-05T19:11:58-00:00

Neuropsychologia, Vol. 45, No. 6. (2007), pp. 1270-1279.

A heightened propensity for risk-taking and poor decision-making underlies the peak morbidity and mortality rates reported during adolescence. Delayed maturation of cortical structures during the adolescent years has been proposed as a possible explanation for this observation. Here, we test the hypothesis of adolescent delayed maturation by using fMRI during a monetary decision-making task that directly examines risk-taking behavior during choice selection. Orbitofrontal/ventrolateral prefrontal cortex (OFC/VLPFC) and dorsal anterior cingulate cortex (ACC) were examined selectively since both have been implicated in reward-related processes, cognitive control, and resolution of conflicting decisions. Group comparisons revealed greater activation in the OFC/VLPFC (BA 47) and dorsal ACC (BA 32) in adults than adolescents when making risky selections. Furthermore, reduced activity in these areas correlated with greater risk-taking performance in adolescents and in the combined group. Consistent with predictions, these results suggest that adolescents engage prefrontal regulatory structures to a lesser extent than adults when making risky economic choices.

Impaired recognition of fear facial expressions in 5-HTTLPR S-polymorphism carriers following tryptophan depletion.

AA Marsh — 2007-02-20T22:42:08-00:00

Psychopharmacology (Berl), Vol. 189, No. 3. (December 2006), pp. 387-394.

RATIONALE: Genotype at the 5' promoter region (5-HTTLPR) of the serotonin transporter has been implicated in moderating the effects of acute tryptophan depletion on neurocognitive functioning. Acute tryptophan depletion has been associated with the processing of fear-relevant cues, such as emotional expressions, but the effect of genotype at the 5-HTTLPR has not been assessed. OBJECTIVE: The present study investigated the effects of acute tryptophan depletion on the recognition of standardized facial expressions of emotions in healthy volunteers classified as ll homozygotes or s carriers. MATERIALS AND METHODS: A double-blind between-groups design was used with volunteers randomly selected to ingest capsules containing an amino acid mixture specifically lacking tryptophan, or placebo capsules containing lactose. 5 h after capsule ingestion, subjects were required to identify anger, disgust, fear, happiness, sadness, and surprise expressions that progressed from neutral to each full emotional expression in 5% steps. RESULTS: Tryptophan depletion significantly impaired the recognition of fearful facial expressions in s carriers but not ll homozygotes. This impairment was specific to fear expressions. No significant differences in the recognition of other expressions were found. Free tryptophan levels were correlated with fear recognition in s carriers but not ll homozygotes. CONCLUSIONS: The effects of acute tryptophan depletion on the processing of emotional expressions varies as a function of genotype at the 5-HTTLPR. Depletion impairs the recognition of fear in s carriers but not ll homozygotes. This finding reinforces the importance of considering genotype when assessing the behavioral effects of pharmacologic modulation.

An fMRI examination of developmental differences in the neural correlates of uncertainty and decision-making

Krain — 2006-10-31T04:52:27-00:00

Journal of Child Psychology and Psychiatry and Allied Disciplines, Vol. 47, No. 10. (November 2006), pp. 1023-1030.

Improvement in the Reproducibility and Accuracy of DNA Microarray Quantification by Optimizing Hybridization Conditions.

Tao Han — 2007-01-10T15:56:07-00:00

BMC Bioinformatics, Vol. 7 Suppl 2 (26 September 2006)

ABSTRACT : BACKGROUND : DNA microarrays, which have been increasingly used to monitor mRNA transcripts at a global level, can provide detailed insight into cellular processes involved in response to drugs and toxins. This is leading to new understandings of signaling networks that operate in the cell, and the molecular basis of diseases. Custom printed oligonucleotide arrays have proven to be an effective way to facilitate the applications of DNA microarray technology. A successful microarray experiment, however, involves many steps: well-designed oligonucleotide probes, printing, RNA extraction and labeling, hybridization, and imaging. Optimization is essential to generate reliable microarray data. RESULTS : Hybridization and washing steps are crucial for a successful microarray experiment. By following the hybridization and washing conditions recommended by an oligonucleotide provider, it was found that the expression ratios were compressed greater than expected and data analysis revealed a high degree of non-specific binding. A series of experiments was conducted using rat mixed tissue RNA reference material (MTRRM) and other RNA samples to optimize the hybridization and washing conditions. The optimized hybridization and washing conditions greatly reduced the non-specific binding and improved the accuracy of spot intensity measurements. CONCLUSION : The results from the optimized hybridization and washing conditions greatly improved the reproducibility and accuracy of expression ratios. These experiments also suggested the importance of probe designs using better bioinformatics approaches and the need for common reference RNA samples for platform performance evaluation in order to fulfill the potential of DNA microarray technology.

Using RNA sample titrations to assess microarray platform performance and normalization techniques

Richard Shippy — 2006-09-09T05:29:36-00:00

Nature Biotechnology, Vol. 24, No. 9. (08 September 2006), pp. 1123-1131.

An extremely rich repertoire of bursting patterns during the development of cortical cultures.

DA Wagenaar — 2006-12-01T04:42:42-00:00

BMC Neurosci, Vol. 7 (2006)

BACKGROUND: We have collected a comprehensive set of multi-unit data on dissociated cortical cultures. Previous studies of the development of the electrical activity of dissociated cultures of cortical neurons each focused on limited aspects of its dynamics, and were often based on small numbers of observed cultures. We followed 58 cultures of different densities--3000 to 50,000 neurons on areas of 30 to 75 mm2--growing on multi-electrode arrays (MEAs) during the first five weeks of their development. RESULTS: Plating density had a profound effect on development. While the aggregate spike detection rate scaled linearly with density, as expected from the number of cells in proximity to electrodes, dense cultures started to exhibit bursting behavior earlier in development than sparser cultures. Analysis of responses to electrical stimulation suggests that axonal outgrowth likewise occurred faster in dense cultures. After two weeks, the network activity was dominated by population bursts in most cultures. In contrast to previous reports, development continued with changing burst patterns throughout the observation period. Burst patterns were extremely varied, with inter-burst intervals between 1 and 300 s, different amounts of temporal clustering of bursts, and different firing rate profiles during bursts. During certain stages of development bursts were organized into tight clusters with highly conserved internal structure. CONCLUSION: Dissociated cultures of cortical cells exhibited a much richer repertoire of activity patterns than previously reported. Except for the very sparsest cultures, all cultures exhibited globally synchronized bursts, but bursting patterns changed over the course of development, and varied considerably between preparations. This emphasizes the importance of using multiple preparations--not just multiple cultures from one preparation--in any study involving neuronal cultures. These results are based on 963 half-hour-long recordings. To encourage further investigation of the rich range of behaviors exhibited by cortical cells in vitro, we are making the data available to other researchers, together with Matlab code to facilitate access.

Choosing the Lesser of Two Evils, the Better of Two Goods: Specifying the Roles of Ventromedial Prefrontal Cortex and Dorsal Anterior Cingulate in Object Choice

Karina Blair — 2006-11-03T10:19:20-00:00

J. Neurosci., Vol. 26, No. 44. (1 November 2006), pp. 11379-11386.

The ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortices (ACd) are considered important for reward-based decision making. However, work distinguishing their individual functional contributions has only begun. One aspect of decision making that has received little attention is that making the right choice often translates to making the better choice. Thus, response choice often occurs in situations where both options are desirable (e.g., choosing between mousse au chocolat or creme caramel cheesecake from a menu) or, alternatively, in situations where both options are undesirable. Moreover, response choice is easier when the reinforcements associated with the objects are far apart, rather than close together, in value. We used functional magnetic resonance imaging to delineate the functional roles of the vmPFC and ACd by investigating these two aspects of decision making: (1) decision form (i.e., choosing between two objects to gain the greater reward or the lesser punishment), and (2) between-object reinforcement distance (i.e., the difference in reinforcements associated with the two objects). Blood oxygen level-dependent (BOLD) responses within the ACd and vmPFC were both related to decision form but differentially. Whereas ACd showed greater responses when deciding between objects to gain the lesser punishment, vmPFC showed greater responses when deciding between objects to gain the greater reward. Moreover, vmPFC was sensitive to reinforcement expectations associated with both the chosen and the forgone choice. In contrast, BOLD responses within ACd, but not vmPFC, related to between-object reinforcement distance, increasing as the distance between the reinforcements of the two objects decreased. These data are interpreted with reference to models of ACd and vmPFC functioning. 10.1523/JNEUROSCI.1640-06.2006

Spectroscopic constants for the 2.5 and 3.0 [mu]m bands of acetylene

WJ Lafferty — 2006-07-18T15:59:47-00:00

Journal of Molecular Spectroscopy, Vol. 141, No. 2. (June 1990), pp. 223-230.

Fourier-transform interferometer and difference-frequency laser spectra of acetylene have been recorded in the 2.5- and 3.0-[mu]m regions, yielding improved rotation-vibration constants for the [nu]3 fundamental and its Fermi-resonant partner, [nu]2 + [nu]4 + [nu]5, for their associated hot bands originating in the [nu]4 and [nu]5 bends, and for the C---H stretch-bend combination bands. An analysis of the Fermi resonance gives more reliable estimates for the deperturbed constants and the anharmonic coupling.

Limbic hyperactivation during processing of neutral facial expressions in children with bipolar disorder

Brendan Rich — 2006-06-07T05:59:08-00:00

PNAS, Vol. 103, No. 23. (6 June 2006), pp. 8900-8905.

Reflecting a paradigm shift in clinical neuroscience, many chronic psychiatric illnesses are now hypothesized to result from perturbed neural development. However, most work in this area focuses on schizophrenia. Here, we extend this paradigm to pediatric bipolar disorder (BD), thus demonstrating traction in the developmental psychobiology perspective. To study amygdala dysfunction, we examined neural mechanisms mediating face processing in 22 youths (mean age 14.21 +/- 3.11 yr) with BD and 21 controls of comparable age, gender, and IQ. Event-related functional MRI compared neural activation when attention was directed to emotional aspects of faces (hostility, subjects' fearfulness) vs. nonemotional aspects (nose width). Compared with controls, patients perceived greater hostility in neutral faces and reported more fear when viewing them. Also, compared with controls, patients had greater activation in the left amygdala, accumbens, putamen, and ventral prefrontal cortex when rating face hostility, and greater activation in the left amygdala and bilateral accumbens when rating their fear of the face. There were no between-group behavioral or neural differences in the nonemotional conditions. Results implicate deficient emotion-attention interactions in the pathophysiology of BD in youth and suggest that developmental psychobiology approaches to chronic mental illness have broad applicability. 10.1073/pnas.0603246103

Use of a mixed tissue RNA design for performance assessments on multiple microarray formats.

KL Thompson — 2006-01-19T01:50:44-00:00

Nucleic Acids Res, Vol. 33, No. 22. (2005)

The comparability and reliability of data generated using microarray technology would be enhanced by use of a common set of standards that allow accuracy, reproducibility and dynamic range assessments on multiple formats. We designed and tested a complex biological reagent for performance measurements on three commercial oligonucleotide array formats that differ in probe design and signal measurement methodology. The reagent is a set of two mixtures with different proportions of RNA for each of four rat tissues (brain, liver, kidney and testes). The design provides four known ratio measurements of >200 reference probes, which were chosen for their tissue-selectivity, dynamic range coverage and alignment to the same exemplar transcript sequence across all three platforms. The data generated from testing three biological replicates of the reagent at eight laboratories on three array formats provides a benchmark set for both laboratory and data processing performance assessments. Close agreement with target ratios adjusted for sample complexity was achieved on all platforms and low variance was observed among platforms, replicates and sites. The mixed tissue design produces a reagent with known gene expression changes within a complex sample and can serve as a paradigm for performance standards for microarrays that target other species.