Senior Vice Chancellor's Research Seminar

Topic Overview:

The brain is often bombarded by streams of information from multiple sources simultaneously. In real world situations, rapidly changing contexts can shift the meaning of a sensory stimulus, requiring an animal to change its response to a given stimulus on the fly. The ability to flexibly and appropriately adjust behavioral responses in changing contexts is critical not only for survival but also to thrive in society. Indeed, disruptions in this ability characterize many brain disorders. The goal of Runyan’s lab is to understand the mechanisms that underlie the flexibility of information processing in cortical circuits, focusing on how inhibitory neurons gate the flow of information between sensory and association regions in a context-dependent manner. Runyan will discuss her recent findings that population codes differ fundamentally between sensory and association cortices, allowing these regions to encode information at different timescales. Activity in neural populations in auditory cortex (AC) and posterior parietal cortex (PPC) were monitored using two-photon imaging of calcium activity while mice performed an auditory localization task in virtual reality. Runyan and colleagues compared coding for sensory stimuli and behavioral choices in AC and PPC, finding that the areas had major differences in functional coupling between neurons, measured as activity correlations that could not be explained by task events. Coupling among PPC neurons was strong, extended over long-time lags, and contributed to a long timescale population code characterized by consistent representations of choice lasting more than two seconds. In contrast, coupling among AC neurons was weak, shorter-lived, and resulted in moment-to-moment fluctuations in stimulus and choice information. Results suggest that population coupling is a variable property that affects the timescale of information coding, and Runyan and colleagues hypothesize that local inhibitory circuits modulate these dynamics. Runyan will discuss ongoing work in the lab to dissect the roles of inhibitory circuits in shifting network dynamics across behavioral contexts and to examine the effects of these shifts on the transmission of information from sensory to association cortex.






							Topic Overview: The brain is often bombarded by streams of information from multiple sources simultaneously. In real world situations, rapidly changing contexts can shift the meaning of a sensory stimulus, requiring an animal to change its response to a given stimulus on the fly. The ability to flexibly and appropriately adjust behavioral responses in changing contexts is critical not only for survival but also to thrive in society. Indeed, disruptions in this ability characterize many brain disorders. The goal of Runyan’s lab is to understand the mechanisms that underlie the flexibility of information processing in cortical circuits, focusing on how inhibitory neurons gate the flow of information between sensory and association regions in a context-dependent manner. Runyan will discuss her recent findings that population codes differ fundamentally between sensory and association cortices, allowing these regions to encode information at different timescales. Activity in neural populations in auditory cortex (AC) and posterior parietal cortex (PPC) were monitored using two-photon imaging of calcium activity while mice performed an auditory localization task in virtual reality. Runyan and colleagues compared coding for sensory stimuli and behavioral choices in AC and PPC, finding that the areas had major differences in functional coupling between neurons, measured as activity correlations that could not be explained by task events. Coupling among PPC neurons was strong, extended over long-time lags, and contributed to a long timescale population code characterized by consistent representations of choice lasting more than two seconds. In contrast, coupling among AC neurons was weak, shorter-lived, and resulted in moment-to-moment fluctuations in stimulus and choice information. Results suggest that population coupling is a variable property that affects the timescale of information coding, and Runyan and colleagues hypothesize that local inhibitory circuits modulate these dynamics. Runyan will discuss ongoing work in the lab to dissect the roles of inhibitory circuits in shifting network dynamics across behavioral contexts and to examine the effects of these shifts on the transmission of information from sensory to association cortex.