Understanding Circuits

PROJECT SUMMARY The basic mechanisms underlying comprehension of spoken language are unknown. We are only beginning to understand how the human brain extracts the most fundamental linguistic elements (consonants and vowels) from a complex and highly variable acoustic signal. Traditional theories have posited a ‘universal’ phonetic inventory shared by all humans, but this has been challenged by other newer theories that each language has its own unique and specialized code.

PROJECT SUMMARY Actions are not mediated solely by cortical processes but rely on communication within basal ganglia- thalamocortical loops. Speech is one example, although how the basal ganglia participate in this uniquely human behavior is not clear, due to a lack of empirical data. For instance, the leading computational model of speech production ignores the hyperdirect cortical pathway to the subthalamic nucleus (STN), a basal ganglia node that has been implicated in multiple cognitive processes relevant to speech production (e.g.

Project Summary/Abstract Decades of research and clinical observations have established that successful spatial navigation and memory depend on the hippocampus and associated structures in the medial temporal lobe (MTL), including entorhinal, perirhinal and parahippocampal cortices [1, 2]. It is thought that the supporting neuronal mechanisms rely on key oscillatory patterns of activity within the MTL that change dynamically when navigating through an environment [3-10].

Project Summary The rapid formation of new memories and the recall of old memories to inform decisions is essential for human cognition, but the underlying neural mechanisms remain poorly understood. The long-term goal of this research is a circuit-level understanding of human memory to enable the development of new treatments for the devastating effects of memory disorders. Our experiments utilize the rare opportunity to record in-vivo from human single neurons simultaneously in multiple brain areas in patients undergoing treatment for drug resistant epilepsy.

Project Summary The same pattern of neural activity can correspond to multiple events in the world. Signals sweeping across the retina, for instance, might be generated by a moving object or by the animal's self-motion. The brain resolves this ambiguity by inferring what events best explain sensory activity. This process, called causal inference, is a foundation of action-perception loops in all sensory-motor systems. To support adaptive action, neural representations of variables involved in these computations should be internally consistent.

Resource Core 3 - Teaching/Training/Dissemination Core (TTDC) Leads: Maisie Lo PhD and Kristin Overton PhD Summary The TTDC’s teaching mission specifically leverages our educational infrastructure for advancing the application of modern neurotechnology methods in short (3-day) or extended-format (3-week) workshops.

PROJECT SUMMARY Goal-directed navigation often occurs in complex, large environments where the same goal can be reached from different starting point and through different routes which are often self-selected. The hippocampus is believed to play a central role in navigation yet it remains poorly understood how it supports the planning and execution of naturally emerging navigation patterns during goal-directed behaviors.

Project Summary Complex motor sequences are fundamental to many highly skilled behaviors, ranging from athletics to musical and vocal expression. Learning such complex movements requires both motor variability, to facilitate exploration important to reinforcement learning, and motor flexibility, to enable the adaptive modification of behavior in response to reinforcement signals. Studies of relatively simple skill learning, such as lever pressing or licking, emphasize that interactions between the motor cortex and the striatum are central to both exploration and reinforcement.

Project summary: Synaptic plasticity in brain structures like the hippocampus has been hypothesized to underlie an essential brain function - consolidating transient experiences into long-lasting memories. The importance of sleep for promoting long-term memory storage, and the disruptive effect of sleep deprivation on memory, have been appreciated for nearly a century. However, it remains unclear how sleep-associated changes in the activity of specific brain circuits contribute to synaptic plasticity in the hippocampus and other structures.

Project Summary/Abstract Sleep is necessary for all brain function and ultimately life. The core function by which sleep contributes to healthy cognition remains one of the great questions facing neuroscience. Recent theories point to powerful cellular rules, but these are controversial and have difficulty accounting for the effects of sleep in ethologically and developmentally diverse circumstances. We recently showed that cortical circuit dynamics are actively tuned to criticality, a computational regime that maximizes information processing.