Understanding Circuits

Abstract This study aims to understand how the ensemble activity and network architecture of a neuronal population guides natural and learned behavior.

Development of predictive coding networks for spatial navigation Summary: Mammalian navigation uses internal models to predict the spatial-temporal statistical regularity of the sequence of environmental locations. Predictive coding theories view the brain as Bayesian interpreter that computes the difference between the external stimuli and an internal model of the world. It is increasingly understood that sequential spatial information is represented by temporal sequences of ensemble neuronal firing in the hippocampus.

Project Summary During behavior, the oculomotor system is tasked with selecting objects from an ever-changing visual field and guiding eye movements to these locations. The attentional priority given to sensory targets during selection can be strongly influenced by external stimulus properties (“bottom-up”) or internal goals based on previous experience (“top-down”).

ABSTRACT A major goal in clinical neuroscience is to develop efficient treatments to prevent or minimize the loss of brain function caused by pathological decreases or increases of neuronal activity, which are hallmarks of a wide variety of neurological disorders. Interestingly, in some instances, the brain has evolved mechanisms to partially correct abnormal neuronal function.

ABSTRACT Persistent neural activity, a sustained response following brief stimuli that is observed in many brain networks, needs to be appropriately tuned to meet the exacting demands of various motor and cognitive tasks. One task that has been particularly amenable to understanding persistent neural activity is the oculomotor control of gaze position.

Thalamocortical state control of tactile sensing: Mechanisms, Models, and Behavior Despite the fact that the sensory thalamus plays a major role in shaping sensory representations in cortex, and thus shaping our percepts, most of what we know has been determined through electrophysiological investigation of the thalamus in-vitro or in the anesthetized brain. Properties of thalamic activity such as mean firing rates, timing and synchrony, and tonic/burst firing directly determine how sensory inputs are represented in the spatiotemporal activation of cortex.

Project Summary / Abstract Our brain provides us with a sense of where we are in space.

ABSTRACT Top-down feedback connections between “higher” and “lower” brain areas are quite common, but their functional role remains a mystery. This general principle applies to the olfactory system, in which the olfactory bulb receives dense feedback innervation from its cortical targets. Here, we propose techniques with which feedback neurons can be targeted by a viral/transgenic intersectional strategy in mice. Using this strategy, we will identify feedback neurons during electrophysiological recordings by optogenetic tagging.

PROJECT SUMMARY The amygdala plays a central role in diverse learned behaviors. By integrating the sensory information with stress, punishment, and reward signals, the circuitry within the amygdala is thought to be modified during learning to mediate specific behavioral outcomes. However, the circuit principles governing what is changed and how different types of learning give rise to qualitatively distinct behaviors remains largely unknown.

Project Summary / Abstract A fundamental but unsolved question in neuroscience is how specific connections between brain cells (neurons) underlie information processing. Circuits in the cerebral cortex—the part of the mammalian brain that underlies high-level sensory, motor, and cognitive function—consists of tens of thousands of neurons, each of which sends and receives thousands of connections. Perhaps the biggest reason we don't understand the cerebral cortex is that we don't have an actual wiring diagram of any single cortical circuit.