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Clinical Brown Bag Series: Steve Brunwasser
September 8, 2015

Steve Brunwasser, Kennedy Center for Research, Vanderbilt University

Tuesday, Sept. 8, 2015

12:10 p.m. Wilson Hall, Room 316

Association Between Antenatal Depression & Anxiety and Neonatal Outcomes:

Maternal Pregnancy Complications as a Mediator

Perinatal mood and anxiety disorders (PMADs) are linked to adverse health outcomes both for mothers and exposed offspring, but little is known about the mechanisms driving these associations. In this session, I will describe an ongoing research project focused on evaluating whether the association between maternal antenatal depression and anxiety and neonatal health outcomes can be accounted for by maternal antenatal health complications. This study is still in its infancy so much of the session will be focused on methodological and statistical challenges, but I will also present preliminary findings. Data are drawn from administrative records of 228,876 pregnant women (ages 15-44) enrolled in Tennessee Medicaid from 1995-2007. Using structural equation modeling, we test the hypothesis that the effects of PMADs on neonatal health outcomes are primarily indirect through antenatal complications. ICD-9 codes are used to identify women carrying depression (n=8851, 4%) and anxiety (n=17958, 8%) diagnoses. The primary outcomes are child birthweight, 5-minute APGAR scores, and probability of neonatal intensive care unit (NICU) admission. We control for covariates including the number of filled antidepressant prescriptions, pre-pregnancy maternal health problems, and demographic variables. Additionally, among women with a depression diagnosis, we evaluate indirect effects of depression severity on neonatal outcomes, with depression severity conceptualized as a reflective latent variable defined by multiple indicators: ICD-9 depression severity code, number of mental health visits, suicide attempt, and psychiatric hospitalization.

 


CCN Brown Bag Series: Ming Meng
September 9, 2015

Ming Meng, Ph.D., Center for Social Brain Sciences. Dartmouth University

Wednesday, Sept. 9, 2015

12:10 p.m. Wilson Hall, Room 115

Fluctuations of fMRI activation patterns underlie the theta-band rhythmic effects of visual object priming

To efficiently interact with an ever-changing environment, the brain dynamically responds to sensory stimulation. Notably, whereas high-frequency gamma band activity may directly underlie neuronal spike coordination (Crick & Koch, 1990), slower waves carrying (multiplexing) faster waves appear to be a common perceptual coding strategy in the brain (VanRullen & Koch, 2003). Recent behavioral studies further suggest a theta-band rhythm (4-7 Hz) in the effects of attention and priming (e.g., Fiebelkorn, Saalmann, & Kastner, 2013; Song et al., 2014; Huang, Chen, & Luo, 2015). Here, I investigate three possible brain mechanisms that may lead to such rhythmic behavioral effects: 1) object representations may be rhythmic in the inferior temporal (IT) cortex; 2) Object representations may be constant, but attentional selection of the representations may be rhythmic; 3) Sensory sampling may be rhythmic as early as the primary visual cortex, therefore all the subsequent processes may also be rhythmic. To test these possibilities, activity corresponding to visual object priming was measured in regions of interest (ROIs) across the whole brain by using fMRI.  Critically, to examine rhythmic effects, time-resolved measurements of fMRI activation patterns were attained by varying trial-by-trial stimulus onset asynchrony (SOA) between prime and probe in small steps of 20ms (equivalent to a 50Hz sampling rate). Our behavioral results replicated previous findings, showing theta-band oscillations in the priming effects of reaction times as a function of SOA. More interestingly, multivariate pattern analysis of the fMRI data also demonstrated theta-band oscillations as a function of SOA and an out-of-phase relationship between congruent and incongruent conditions in the IT cortex. No such effects were found in the BA17 or the frontoparietal attention network. This study is the first to map theta-band rhythms across the whole human brain using fMRI. Our results suggest that object representation is oscillatory with theta-band rhythms in the IT cortex, providing insights to understanding the dynamic mechanisms underlying visual perception.

 


Neuroscience Brown Bag Series: Siyuan Yin
September 10, 2015

Siyuan Yin, Department of Psychology, Vanderbilt University

Thursday, Sept. 10, 2015

12:10 p.m. Wilson Hall 316

Do Supplementary Eye Field and Frontal Eye Field Encode Eye Position?

Since its identification in 1987 by Schlag & Schlag-Rey, the supplementary eye field (SEF) has been investigated from diverse perspectives. Initial and subsequent studies of SEF reported that both the direction and amplitude of saccades evoked by intracortical microstimulation as well as the discharge rate of neurons could often vary with eye position. As comparison, FEF was reported to encode actual saccade movement evoked by targets, but not targets spatial location or retinal location. To obtain an unbiased sample of neurons across depth, and to determine the laminar distribution of this orbital tuning in SEF, we analyzed the activity of neurons that were recorded with a linear electrode array oriented perpendicular to the cortex at sites from which contra-lateral, convergent saccades were evoked with low currents. Single unit recording in FEF was used to compare orbital dependence with SEF. The data were collected in three head-fixed macaque monkeys performing a saccade countermanding task. Orbital dependence was assessed from neuronal activity during the inter-trial interval when the monkey's gaze was unconstrained by fitting parabolic surfaces to the variation of discharge rates over gaze position.  Neurons were classified based on responses to the visual stimuli, correct and error saccade production and inhibition and reward anticipation and delivery. In a sample of 262 SEF neurons (96 recorded in monkey Eu; 166 in monkey X) we found that ~70% in Eu and ~30% in X showed orbital dependence based on significantly better fits of a parabolic surface given discharge rate peaked at eccentric gaze angles in multiple directions in some neurons. In a sample of 90 FEF neurons in monkey Br there were ~70% in Br, which showed orbital dependence fitted by quadratic regression model. Orbital tuning was also observed through an analysis contrasting discharge rates associated with two types of saccades, fixed vector and goal directed saccades. A pronounced preference of SEF for contra-lateral orbital positions was found, while no pronounced preference of FEF was found. In both monkeys we found similar proportions of neurons with orbital tuning in all layers of SEF. The presence of orbital tuning was not associated with any particular time or pattern of modulation observed during the countermanding trials. The variation in incidence across monkeys may arise from actual inhomogeneity within SEF or incidental greater number of recording penetrations in X relative to E. However, these results indicate that orbital tuning is a general property that SEF and FEF can distribute to both cortical and subcortical outputs.

 

 

 

 

 

 

 

 

 


CSLD Research Forum - language processing in conversation
September 11, 2015

CSLD Research Forum hosting: Sarah Brown-Schmidt, Ph.D., Associate Professor, University of Illinois

Title: Language processing in conversation

In conversation, each person brings to the conversation a different perspective on the world, including different background knowledge, beliefs and experiences. A central problem in the study of language processing is how speakers and listeners represent the perspectives of other people, and use these representations to facilitate communication. I will discuss several lines of research examining how language use and processing is tailored to the perspective of one’s conversational partner. This research examines both the process of language production (speaking) and language comprehension (listening), in both two-party conversation and conversations in larger groups. Complementary studies examine how partner-specific adaptations are affected in the face of severe declarative memory impairment (hippocampal amnesia).

The results of this research inform our understanding of how the most basic form of language use—interactive conversation—is tailored to different individuals as it is processed in real time. By comparing the performance of individuals with severe declarative memory impairment with healthy matched comparisons, we are able to expand our understanding of the memory systems that support these processes, as well as test long-standing claims of the dependence of partner-specific representations on declarative memory. Studies of language processing in multiparty conversation address theoretical questions regarding the representation of others’ belief states, and have implications for language use in a variety of settings, including educational contexts.

 


Clinical Brown Bag Series: Carissa Cascio
September 15, 2015

Carissa Cascio, Child and Adolescent Psychiatry, Vanderbilt University Medical Center

Tuesday, Sept. 15, 2015

12:10 p.m. Wilson Hall, Room 316

TITLE AND ABSTRACT: TBA


CCN Brown Bag Series: Miguel Eckstein
September 16, 2015

Rapidly looking at faces: A sensory optimization theory

Miguel P. Eckstein, Department of Psychological and Brain Sciences, University of California, Santa Barbara

Wednesday, Sept. 16, 2015

12:10 p.m. Wilson Hall, Room 115

When viewing a human face people first look towards the eyes. A prominent idea holds that these fixation patterns arise solely due to social norms.  Here, I propose that this behavior can be explained as an adaptive brain strategy to learn eye movement plans that optimize the rapid extraction of visual information for  evolutionarily important perceptual tasks. I show that humans move their eyes to points of fixation that maximize perceptual performance determining the identity, gender, and emotional state of a face. These initial optimal points of fixation, which vary moderately across tasks, are correctly predicted by a foveated Bayesian ideal observer (FIO) that takes into account the task, integrates information optimally across the face but is constrained by the decrease in resolution and sensitivity from the fovea towards the visual periphery.  A model that disregards the foveated nature of the visual system and makes eye movements either to the regions/features with the highest discriminative information or center of the face fails to predict the human fixations.   The preferred points of initial fixation are similar across cultural groups (East Asians vs. Caucasians).    However,  there are individual differences with a majority of observers (~ 85 %) looking just below the eyes while a minority ( ~ 15) closer to the tip of the nose and below.  The systematic differences in initial points of fixation persist over time and also correspond to individual variations in the points of fixation that maximize perceptual performance.   Finally , observers have difficulty changing their eye movement plans when confronted with unusual faces or simulated scotomas that make their over-practiced preferred points of fixation suboptimal.  Together, these results illustrate how the brain optimizes initial eye movements to rapidly extract information from faces based on the statistical distribution of discriminatory information, general properties of the human visual system and individual specific neural characteristics, and also highlight the ingrained nature of these highly practiced motor programs.

References:

Or, C.F.C., Peterson, M.F., Eckstein M.P., Initial eye movements during face identification are optimal and similar across cultures, Journal of Vision, 2015 (in press)

Peterson, M. F., & Eckstein, M. P. Learning optimal eye movements to unusual faces. Vision Research, 99, 57-68 (2014)

Peterson, M. F., & Eckstein, M. P. Individual Differences in Eye Movements During Face Identification Reflect Observer-Specific Optimal Points of Fixation , Psychological science, 24(7), 1216-25, (2013)

 

Peterson, M. F., & Eckstein, M. P. Looking just below the eyes is optimal across face recognition tasks. Proceedings of the National Academy of Sciences, 109(48), E3314-E3323  (2012).

 


Clinical Brown Bag Series: Andre Christie-Mizell
September 22, 2015

Andre Christie-Mizell, Ph.D., Sociology Department, Vanderbilt University

Tuesday, Sept. 22, 2015

12:10 p.m. Wilson Hall 316

TITLE AND ABSTRACT: TBA


CCN Brown Bag Series: Sean Polyn
September 23, 2015

Sean Polyn, Ph.D., Department of Psychology, Vanderbilt University

Wednesday, Sept. 23, 2015

12:10 p.m. Wilson Hall, Room 115

Title and Abstract: TBD


Clinical Brown Bag Series: No Talk Scheduled
September 29, 2015

NO TALKS SCHEDULED FOR THIS DATE  (Kennedy Center Science Day)


CCN Brown Bag Series: Joel Pearson
September 30, 2015

Joel Pearson, School of Psychology, University of New South Wales

Wednesday, Sept. 30, 2015

12:10 p.m. Wilson Hall, Room 115

Title and Abstract: TBD


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