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University of Pittsburgh Department of Psychology Colloquium
Title: Being Face-to-Face but Not Seeing Eye-to-Eye: Divergent Experiences and Goals during Intergroup Interactions
Presenter: J. Nicole Shelton, Ph.D.
Location: Martin Room 4127 Sennott Square
Abstract:
Interpersonal interactions can be enjoyable, rejuvenating, and fulfilling; but they can also be anxiety-provoking, exhausting, and disappointing. More often than not, these latter descriptors characterize interactions that occur across racial lines. Because of negative attitudes and expectancies, and oftentimes despite good intentions, interracial interactions are fertile ground for stress and misunderstandings. Nonetheless, interacting with out-group members can be valuable and is a requisite aspect of a multicultural society. In this talk, I will discuss how Whites’ and ethnic minorities’ interpersonal concerns with prejudice influence outcomes for the self and their partner during interracial interactions that often result in individuals having divergent experiences in the same situation. In addition, I will discuss how Whites’ and ethnic minorities’ behaviors evolve across time in divergent ways during interracial interactions, ultimately influencing the development of interracial friendships. In essence, I hope to illustrate that it is possible for multiple realities to exist within an interracial encounter, leaving Whites and ethnic minorities feeling as if they live in two different worlds.
Dissertation Defense
Title: Experience-dependent Plasticity of Layer 2/3 Circuits in Developing Somatosensory Neocortex
Presenter: Jing Wen
Location: Mellon Institute Room 448
Abstract: Experience-dependent plasticity is the adaptability of brain circuits as a result of
changes in neural activity, a phenomenon that has been proposed as the neural
basis for important brain functions in health and disease. The underlying
mechanisms of experience-dependent plasticity can take different forms,
depending on the organisms and brain areas under investigation. A better
understanding of these mechanisms will help to interpret normal brain functions
as well as to guide therapies for neurological diseases. Mouse vibrissa system
offers great experimental advantages to studying experience-dependent
plasticity and the underlying molecular mechanisms at different levels.
Using sensory experience paradigms of unbalanced whisker activity, we find that
sensory experience induces rapid synaptic strengthening at excitatory synapses
converged onto single layer 2/3 pyramidal neurons, although the plasticity at
these synapses displays remarkable input specificity. Furthermore, we discover
that recently potentiated layer 4-2/3 excitatory synapses are labile and subject to
activity-dependent weakening in vitro. Calcium-permeable AMPARs
(CP-AMPARs) that are sometimes associated with synaptic strengthening are not
essential for activity-induced synaptic weakening. Finally, we demonstrate that
ongoing sensory experience triggers distinct phases of synaptic plasticity, which
are tightly correlated with changes in NMDAR properties and function. Taken
together, the results from this thesis show distinct manifestations and
mechanisms of how sensory experience modulates synaptic properties and
neuronal function that may provide insights into information processing and
coding in the neocortex.
Title: Enhancements of sparse clustering with resampling and considerations on tuning parameter
Presenter: Wenzhu Bi
Location: A622 Crabtree Hall
Abstract:
Clustering methods are widely used to explore subgroupings in data when
the true group membership is unknown. These techniques are very useful
when identifying potential subpopulations of interest in the medical and
public health setting. Examples of these types of subpopulations include
subjects who have certain gene expression profiles related to a cancer
subtype, and subjects who are in the very early, asymptomatic phase, of
a chronic illness. All of these examples are of great public health
relevance.
Many of the datasets of interest arise from the development of new
technologies and are subject to the common problem where p, the number
of variables, is significantly larger than the sample size, n. The
relatively small sample size, n, may result from the difficulties of
subject recruitment and/or the financial burden of the actual data
collection in fields such as imaging and genetic analysis. The earlier
approaches to clustering treat all of the variables equally, which may
not work well when not all of them are relevant to the subgroupings.
Clustering methods with variable selection, also called sparse
clustering, have been recently developed to deal with this problem. We
propose a method to add resampling onto sparse clustering to improve
upon the current clustering methodology. The addition of resampling
methods to sparse clustering results in variable selection that is more
accurate. The method is also used to assign an “observed proportion of
cluster membership” to each observation, providing a new metric by which
to measure membership certainty. The performance of the method is
studied via simulation and illustrated in the motivating data example.
We also propose an alternative approach for the choice of tuning
parameter based on an adjusted Bayesian Information Criterion (BIC).
Variable selection in sparse clustering is realized by applying Lasso or
related penalties and the tuning parameter for these penalties has to be
determined beforehand. The gap statistic, a distance-based approach, is
used to choose the tuning parameter through permutation and it may
behave poorly at times. The proposed BIC approach is an alternative
developed under the more sophisticated model-based likelihood framework.
Its performance is evaluated with simulations.
Title: Neurosurgical Studies of Normal Human Brain Physiology
Presenter: Matthew A. Howard, III, MD
Location: 1495 BST
Abstract: TBA
Title: Roles of olfactory receptor neurons in establishing neural codes for odors
Presenter: Mark A. Stopfer, Ph.D.
Location: 2nd floor Auditorium, Learning Research Developemt Center
Abstract: TBA
Title: Reading and Writing the Neural Code in Sensory Pathways of the Brain
Presenter: Garrett Stanley, Ph.D.
Location: Margaret Morrison 103
Abstract:
The external world is represented in the brain as spatiotemporal
patterns of electrical activity. Sensory signals, such as light,
sound, and touch, are transduced at the periphery and subsequently
transformed by various stages of neural circuitry, resulting in
increasingly abstract representations through the sensory pathways of
the brain. It is these representations that ultimately give rise to
sensory perception. Deciphering the messages conveyed in the
representations is often referred to as “reading the neural code”.
True understanding of the neural code requires knowledge of not only
the representation of the external world at one particular stage of
the neural pathway, but ultimately how sensory information is
communicated from the periphery to successive downstream brain
structures. Our laboratory has focused on various challenges posed by
this problem, some of which I will discuss. In contrast, prosthetic
devices designed to augment or replace sensory function rely on the
principle of artificially activating neural circuits to induce a
desired perception, which we might refer to as “writing the neural
code”. This requires not only significant challenges in biomaterials
and interfaces, but also in knowing precisely what to tell the brain
to do. Our laboratory has begun some preliminary work in this
direction that I will discuss. Taken together, an understanding of
these complexities and others is critical for understanding how
information about the outside world is acquired and communicated to
downstream brain structures, in relating spatiotemporal patterns of
neural activity to sensory perception, and for the development of
engineered devices for replacing or augmenting sensory function lost
to trauma or disease.
Title: Neural substrates of motor skill learning in the healthy brain and after stroke
Presenter: Leonardo G. Cohen, M.D.
Location: Biomedical Science Tower 3, 6014
Abstract: TBA
Title: Functional transformations in the auditory midbrain: implications for hearing prosthetics
Presenter: Chen Chen, Ph.D.
Location: Keystone Building, 3520 Fifth Ave. Stoner Conference Room 2nd Floor
Abstract:
Sound information is decomposed into spectro-temporal components at the cochlea and distributed into parallel processing pathways via multiple brainstem nuclei. These diverse pathways ultimately all converge in the inferior colliculus (IC), the principal midbrain auditory structure. Sound information is comprehensively processed within the IC before being passed on to the thalamus and auditory cortex. Yet, little is known about this functional transformation, i.e. how it integrates and transforms incoming sensory inputs and produces processed neural responses for information readout. To characterize the transformation performed by the IC, large-scale electrodes arrays were used to measure neural population response to sound. In this talk I will describe the 1) transformation between brainstem inputs and target IC neurons; 2) how sound sensitivities are systematically organized in the IC volume; and 3) The efficiency of IC population codes. The results of these studies will help define how sound information is processed by the IC and will benefit next-generation hearing prosthetics (e.g. brainstem implants or midbrain implants).