Aug. 30th, 2019

#1113, Wang Kezhen Building, Peking University

08:50      Opening Remark

09:00-09:25

Speaker: Dr. John-Dylan Haynes, Charité - Universitätsmedizin, Berlin

Topic: Distributed working memory representations in the human brain

Abstract:

Studies in humans and non-human primates have provided evidence for storage of working memory contents in multiple regions ranging from sensory to parietal and prefrontal cortex. We present two examples of a specialisation of areas in working memory encoding in humans. In a first study we looked into the role of attention. Items held in working memory can be either attended or not, depending on their current behavioral relevance. It has been suggested that unattended contents might be solely retained in an activity-silent form. We show that encoding unattended contents involves a division of labor. While visual cortex only maintains attended items, intraparietal areas and the frontal eye fields represent both attended and unattended items. In a second study we examined the role of continuous versus categorical representations using color stimuli that are memorized across brief delays. We found that during storage activity patterns already in visual regions exhibit a degree of categorical information. Taken together our results suggest that storage of working memory contents is based on a network of regions, rather than relying on a single location.

9:30-9:55

Speaker: Dr. Robert Desimone, Department of Brain and Cognitive Sciences, MIT

Topic: Autistic-like behavior and connectivity in SHANK3 mutant macaques

Abstract:

Mutation or disruption of the SHANK3 (SH3 domain and ankyrin repeat) gene represents a highly penetrant, monogenic risk-factor for Autism Spectrum Disorder (ASD) and is a cause of Phelan–McDermid syndrome (PMS). Recent advances in gene editing have enabled the creation of genetically engineered non-human primate (NHPs) models, which might better approximate the behavioral and neural abnormalities of ASD than rodent models and lead to more effective treatments. I will describe our CRISPR/Cas9-mediated generation of germline-transmissible cynomolgus macaques and their F1 offspring carrying SHANK3 mutations. Genotyping of somatic cells and brain biopsies confirmed mutations in the SHANK3 gene and reduced SHANK3 proteins. Analysis of fMRI data revealed altered local and global connectivity patterns indicative of circuit abnormalities. The founder mutants exhibited sleep disturbances, motor deficits, and increased repetitive behaviors, as well as social and learning impairments. Together, these results parallel some aspects of the gene-circuit-behavior dysfunction in human ASD and PMS. 

09:55-10:15      Coffee Break

10:15-10:40

Speaker: Dr. Daniel Kersten, Department of Psychology, University of Minnesota

Topic: The perception of natural flows

Abstract:

Human vision has the ability to draw rich interpretations of moving materials (e.g. water waves, smoke, windblown foliage, etc.). Vision's facility is remarkable given that the retinal input is a high-bandwidth, complex function of intrinsic physical, geometric and photometric properties of substances, and their interactions with light and viewpoint. I'll show examples of natural dynamic flows that illustrate our abilities to ``decode'' flow patterns to infer their properties and causes. Analogous to object perception, these observations demonstrate how inferences about flows range over levels of abstraction from  shallow properties such as color and optic flow, to deeper attributes such as viscosity and elasticity, and further to support affordances, for example whether a material is penetrable. The "depth" of these decisions depends critically on the spatial and temporal context. I'll describe results in which we measured perceptual judgments of material category, attributes, affordances, and between-flow similarities. I'll also review relevant work on modeling natural flows and the computational challenges for understanding how the brain supports flow perception and inferences that range from shallow to deep.

10:45-11:10

Speaker: Dr. Sheng He, State Key Laboratory of Brain & Cognitive Sciences

Topic: Processing words and faces in the Occipito-Temporal Cortex: selectivity, connectivity, and plasticity

Abstract:

The human occipito-temporal cortex (OTC) has many specialized regions, notably regions related to our expertise in word and face recognition. In this talk, I will report results from brain imaging studies targeting the word- and face-sensitive regions in the OTC. Specifically, I will describe their functional selectivity (what are the critical features in the stimuli that drive each ROI's response); functional connectivity (networks within and beyond the OTC for word and face processing), and their plasticity (training induced word and face selectivity after the critical period).