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CNBC Colloquium
Title: Neuronal mechanisms of visual categorization and decision making
Presenter: David Freedman, Ph.D.
Location: 6014 BST3
Abstract: We have a remarkable ability to recognize the behavioral significance, or category membership of a wide range of visual stimuli. While much is known about how simple visual features (such as color, orientation and direction of motion) are processed in early stages of the visual system, much less is known about how the brain learns and recognizes categorical information that gives meaning to incoming stimuli. This talk will review a series of neurophysiological and behavioral experiments aimed at understanding the neuronal representations underlying visual categorization and decision making with a focus on parietal and prefrontal cortices. We have found that the activity of individual neurons in both the posterior parietal and lateral prefrontal cortices can reflect the learned category membership of visual stimuli, and that these two areas play distinct roles in category-based decision making. The relationship between non-spatial cognitive signals and spatial signals (related to attention and eye movements) in parietal cortex will also be discussed.
Title: "The role of striatal microcircuits in basal ganglia disorders"
Presenter: Aryn Gittis, PhD
Location: 1495 BST3
Sponsored by the Department of Neurobiology
Department of Neurobiology, University of Pittsburgh Presents a Special Seminar:
Title: "Synaptic circuit organization of mouse motor cortex"
Presenter: Gordon M. G. Shepherd, MD, PhD
Location: 6014 Biomedical Science Tower 3
Ph.D. Dissertation Defense
Title: Characterizing the Spatiotemporal Neural Representation of Concrete Nouns Across Paradigms
Presenter: Gustavo Sudre -Neural Computation -Center for the Neural Basis of Cognition
Location: Gates 8102
Abstract: Most of the work investigating the representation of concrete nouns in the brain has focused on the locations that code the information. We present a model to study the contributions of perceptual and semantic features to the neural code representing concepts over time and space. The model is evaluated using magnetoencephalography data from different paradigms and not only corroborates previous findings regarding a distributed code, but provides further details about how the encoding of different subcomponents varies in the space-time spectrum. The model also successfully generalizes to novel concepts that it has never seen during training, which argues for the combination of specific properties in forming the meaning of concrete nouns in the brain. The results across paradigms are in agreement when the main differences among the experiments (namely, the number of repetitions of the stimulus, the task the subjects performed, and the type of stimulus provided) were taken into consideration. More specifically, these results suggest that features specific to the physical proper- ties of the stimuli are encoded in posterior regions of the brain in the first hundreds of milliseconds after stimulus onset. Then, properties inherent to the nouns are rep- resented in the signal starting at about 250 ms, focusing on more anterior parts of the cortex. The code for these different features was found to be distributed over time and space, and it was common for several regions to simultaneously code for a particular property. Moreover, most anterior regions were found to code for multiple features, and a complex temporal profile could be observed for the majority of properties. These findings complement much of the work previously described in the literature, and offer new insights about the temporal aspects of the neural encoding of concrete nouns. This model provides a spatiotemporal signature of the representation of objects in the brain. Paired with data from carefully-designed paradigms, the model is an important tool with which to analyze the commonalities of the neural code across stimulus modalities and tasks performed by the subjects.
Presenter: Warren Grill, PhD Addy Professor of Biomedical Engineering Duke University
Location: Margaret Morrison 103
Abstract: Deep brain stimulation (DBS) has developed from an experimental technique to an established therapy for the treatment of movement disorders including dystonia, essential tremor, and Parkinson's disease. High frequency stimulation results in outcomes similar to those resulting from ablative surgical lesions of target structures in the thalamus and basal ganglia, but debate remains over the effects of high frequency stimulation on neuronal and network activity. I will present both computational and experimental studies that illuminate the cellular and network mechanisms of DBS. I first will review the effects of extracellular stimulation on the activity in CNS neurons and use these results as motivation of a hypothesis that DBS acts by regularizing the activity in populations of neurons in the stimulated nucleus. Next, I will present experimental data from preclinical experiments demonstrating that effective DBS results in regularization of neuronal activity and that regularization is responsible for the observed behavioral effects. Third, I will present data from experiments in persons with Parkinson's disease that demonstrate the importance of the regularization of neuronal activity in the clinical efficacy of DBS in treatment of braddykinesia. This regularization acts to mask the patterns of pathological activity that are present in the basal ganglia and thalamus in movement disorders. This new understanding has important implications for novel methods of stimulation, and I will conclude with some recent results with novel temporal patterns of stimulation that increase efficacy or efficiency of DBS in persons with Parkinson's disease.
Presenter: Hugh Garavan, Ph.D.
Associate Professor of Psychiatry, The University of Vermont, and
Adjunct Associate Professor of Psychology, Trinity College, Dublin, Ireland
Location: A219B Langley Hall
Sponsored by the Department of Psychiatry
University of Pittsburgh
Title: Cultural-Existential Psychology:An Integrative Framework for Understanding Responses to Suffering and Threat
Presenter: Daniel Sullivan
Department of Psychology
University of Kansas
Location: Glaser Auditorium, 2nd Floor, LRDC
Abstract: How do people cope with negative events, such as natural disasters or a loved one’s death? Two sub-areas have arisen in social psychology that could shed light on these issues. One is existential psychology, which investigates how humans pursue meaning and self-esteem in the face of threats like awareness of impending mortality. Another is cultural psychology, which documents diversity in motivation and cognition across settings. Cultural-existential psychology is presented as a novel framework for integrating insights from these sub-areas to understand how people respond to intense suffering and threat. Specifically, this framework presumes that culture significantly filters people’s experience of threats and predisposes them to different coping mechanisms. Supporting this perspective, data are presented from experiments that ask people to imagine or witness threatening events, such as watching a video of a destructive tornado. Further data are presented from a cross-cultural study comparing threat responses of college undergraduates to those of a rural, conservative Mennonite population.
Sponsored by the Department of Psychology
Department of Neurology
Grand Rounds Series
Title: "Translational Stroke Research from Animal to Human: Problems and Hopes"
Presenter: Jun Chen, MD
Professor of Neurology and Pharmacology
Endowed Chair and Director
Center of Cerebrovascular Disease Research
University of Pittsburgh
Location: 1105AB Scaife Conference Center
Ph.D. Dissertation Defense
Title: Role of monkey prefrontal cortex in encoding multiple items in working memory
Presenter: Roma Konecky
Center for Neuroscience
Kenneth P. Dietrich School of Arts & Sciences/Neuroscience
Location: A219B Langley Hall
Title: Prefrontal and posterior parietal contributions to cognitive processing
Presenter: Christos Constantinidis, Ph.D.
Associate Professor
Department of Neurobiology & Anatomy
Wake Forest University School of Medicine
Location: A219B Langley Hall
(Sponsored by the Department of Neuroscience)