Circuit Diagrams

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.

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.

Project Summary To survive, organisms must both accurately represent stimuli in the outside world, and use that representation to generate beneficial behavioral actions. Historically, these two processes – the mapping from stimuli to neural responses, and the mapping from neural activity to behavior – have largely been treated separately. Of the two, the former has received the most attention. Often referred to as the “neural coding problem,” its goal is to determine which features of neural activity carry information about external stimuli.

Overview - Abstract Brainstem function is necessary for life-sustaining functions such as breathing and for survival functions, such as foraging for food. Individual motor actions are activated by specific brainstem cranial motor nuclei. The specificity of individual motor actions reflects the participation of motor nuclei in circuits within closed loops between sensors and muscle actuators. However, these loops are also nested and connect to feedback and feedforward pathways, which underlie coordination between orofacial motor actions.

PROJECT SUMMARY/ABSTRACT The mammalian brain has a remarkable ability to store and retrieve information. Detailed memories can be formed after as little as one exposure, and those memories can be retained for decades. This ability is compromised following damage to structures located in the medial temporal lobe, including the hippocampus and the adjacent cortex.

PROJECT SUMMARY Cervical spinal cord injury results in the loss of arm and hand function, which significantly limits independence and results in costs over the person’s lifespan. A brain-computer interface (BCI) can be used to bypass the injured tissue to enable control of a robotic arm and to provide somatosensory feedback. Two primary limitations of current state-of-the-art BCIs for arm and hand control are: (1) the inability to control the forces exerted by the prosthetic hand and (2) the lack of somatosensory feedback from the hand.

Understanding the cerebral cortex requires data-based theoretical models that can yield in- sight into the circuit mechanisms of cortical computation, and reproduce detailed cortical dynamics across stimuli and brain states. The primary visual cortex (V1) is the best-studied cortical area by both theorists and experimen- talists, yet current models - whether statistical or circuit based – only poorly capture how V1 neurons respond to complex stimuli, such as natural scenes.

Oxytocin is a peptide hormone synthesized and released from the hypothalamus for reproduction and maternal behavior. Recent studies have tagged oxytocin as a “trust” hormone, promising to improve social deficits in various mental disorders, such as autism. Despite the enthusiasm for oxytocin, contradictory results in the efficacy of oxytocin in improving human social behaviors have been reported. Such inconsistency in literature is likely due to our poor understanding of complexity of oxytocin action, which likely varies with behavioral state, experience and brain structures.