Event Time and Location: Wednesday, October 18th @ 3PM in Steinman Hall Rm 402

David J. Christini, Ph.D. (Vice Dean, Weill Cornell Graduate School Professor, Department of Medicine Weill Cornell Medicine) Utilizing intact cardiac cell electrophysiological protocols to create more robust computational models

Abstract: The traditional paradigm for developing cardiac computational cell models utilizes data from
multiple cell types, species, laboratories, and experimental conditions to create a composite model.
While such models can accurately represent data in limited biological scenarios, their ability to predict
behavior outside of a narrow dynamic window is limited. This talk will describe novel
electrophysiological protocols that aim to densely sample the dynamics of intact cardiac myocytes. The
information-rich data from such protocols are then fit using complex parameter optimization
algorithms to tune multiple model parameters at one time. By so doing, this approach yields cell
models that fit wide-ranging cellular behavior, making them better suited to make physiological and
pathophysiological predictions.

Event Time and Location: Thursday 10/26 at noon in CDI 3.352

Samantha Cohen will lead a discussion of  the linked paper:
“Natural speech reveals the semantic maps that tile human cerebral cortex “
The meaning of language is represented in regions of the cerebral cortex collectively known as the ‘semantic system’. However, little of the semantic system has been mapped comprehensively, and the semantic selectivity of most regions is unknown. Here we systematically map semantic selectivity across the cortex using voxel-wise modelling of functional MRI (fMRI) data collected while subjects listened to hours of narrative stories. We show that the semantic system is organized into intricate patterns that seem to be consistent across individuals. We then use a novel generative model to create a detailed semantic atlas. Our results suggest that most areas within the semantic system represent information about specific semantic domains, or groups of related concepts, and our atlas shows which domains are represented in each area. This study demonstrates that data-driven methods—commonplace in studies of human neuroanatomy and functional connectivity—provide a powerful and efficient means for mapping functional representations in the brain.

Event Time and Location: Wednesday, October 18th @ 3PM in Steinman Hall Rm 402

Dr. Qi Wang (Department of Biomedical Engineering, Columbia University), Top-down and bottom-up modulation of neural coding in the somatosensory thalamus.

Abstract: The transformation of sensory signals into spatiotemporal patterns of neural activity in the brain is critical in forming our perception of the external world. Physical signals, such as light, sound, and force, are transduced to neural electrical impulses, or spikes, at the periphery, and these spikes are subsequently transmitted to the neocortex through the thalamic stage of the sensory pathways, ultimately forming the cortical representation of the sensory world. The bottom-up (by external stimulus properties) or top-down (by internal brain state) modulation of coding properties of thalamic relay neurons provides a powerful means by which to control and shape information flow to cortex. My talk will focus on two topics. First, I will show that sensory adaptation strongly shapes thalamic synchrony and dictates the window of integration of the recipient cortical targets, and therefore switches the nature of what information about the outside world is being conveyed to cortex. Second, I will discuss how the locus coeruleus – norepinephrine (LC-NE) system modulates thalamic sensory processing. Our data demonstrated that LC activation increased the feature sensitivity, and thus information transmission while decreasing their firing rate for thalamic relay neurons. Moreover, this enhanced thalamic sensory processing resulted from modulation of the dynamics of the thalamorecticulo-thalamic circuit by LC activation. Taken together, an understanding of the top-down and bottom-up modulation of thalamic sensory processing will not only provide insight about neurological disorders involving aberrant thalamic sensory processing, but also enable the development of neural interface technologies for enhancing sensory perception and learning.