We work on neural computation and memory in cortical circuits. Using a modeling approach, at the interface between systems neuroscience and cellular neurophysiology, our goal is to uncover the principles of cortical functions in terms of cellular mechanisms, network connectivity, and large-scale population dynamics. We emphasize close collaboration with experimental laboratories.
Biophysical mechanisms of working memory.A major focus of our research is working memory, the brain's ability to hold and manipulate information on-line while ignoring distractions from the external world. The obligatory physical processes underlying working memory are persistent neural firing patterns that are self-sustained internally in a recurrent network. In collaboration with physiology labs, we develop biophysically realistic models to elucidate the synaptic and cellular mechanisms of stimulus-specific persistent activity underlying working memory, especially in the prefrontal cortex (see movie of our spatial working memory model).
Cognitive functions of working memory circuits.We investigate the operations of reverberatory cortical networks characterized by neural integration and persistent activity. In particular, we study how a reverberatory network is able to subserve perceptual decision making (which requires slow integration of ambiguous sensory data and formation of a categorical decision); or selective attention by providing a sustained top-down signal (by virtue of persistent activity) to sensory systems.
Physiology and computation of single neurons/synapses.We are interested in the cellular mechanism and computational power of bursting firing patterns, and in the neuronal and synaptic dynamics that underlie perceptual adaptation. Furthermore, we combine experimental, biophysical modeling, and information theory approaches to test the hypothesis that the same adaptation mechanisms can reduce redundancy of sensory data, thereby decorrelating the inputs and contributing to efficient neural coding of the external world.
Neural rhythms and synchronization.Coherent oscillations represent a commonly observed network phenomenon in the brain. We have previously discovered that mutual inhibition between interneurons provides a sychronizing mechanism for coupled neurons. We pursue our work in this direction, and advance biophysical models and analytical theory for various types of brain rhythms, including sleep oscillations in the thalamus, gamma oscillations during waking states, slow (< 1 Hz) oscillations and wave propagation in the neocortex, and theta oscillations in the limbic system.