Understanding Circuits

Project Summary Dopamine plays a central role in motivation and reinforcement learning, allowing animals to take advantage of their current circumstances to optimize both present and future behavior. Yet reconciling the diverse roles of dopamine has remained a challenge, in part due to the difficulty of understanding how a single neuromodulator can convey different signals to its cellular targets in distinct behavioral contexts.

PROJECT SUMMARY/ABSTRACT Humans and numerous other species live in complex social environments, requiring many of our most important decisions to be made in the context of social interactions. All of our social relationships rely on our ability to make context-appropriate decisions, including significant ties with committed partners, family, and friends. The social decision-making (SDM) network hypothesis suggests that the expression of a given social behavior is reflected by the overall activity of a network of structures rather than activity of any single structure.

Abstract The focus of this BRAIN Initiative funding opportunity is to use “innovative approaches to understand how circuit activity gives rise to a specific behavior”. Cognitive behaviors arise from collective interactions of multiple brain systems.

Abstract The neurobiology of perceptual decision-making elucidates fundamental neural mechanisms of higher cognitive function, the understanding of which will inspire new strategies to treat neurological and psychiatric diseases affecting thought, perception and awareness. The inquiry focuses on processes that intervene between the acquisition of sensory evidence and commitment to a proposition, behavioral choice, or plan.

Project Summary Understanding how neural circuits create animal behavior requires knowing the system-wide activity patterns that connect sensory experience to motor activities, all within the full set of feedback loops by which actuated motor decisions modulate the animal's perceptions of itself and the outside world during naturally executed and unrestrained behaviors. Mechanistic understanding further requires interpretation of system-wide activity patterns in terms of the connectivity, synaptic, and cellular properties of all relevant neurons.

Project Summary/Abstract Impairments in social functioning is a prominent, debilitating symptom in many neuropsychiatric disorders, such as autism spectrum disorders, schizophrenia, and major depressive disorder. Currently the neural underpinnings of these social deficits are poorly understood, and effective therapeutic approaches are still lacking. Elucidation of the neural circuit mechanisms for social behaviors will improve our understanding of the disease mechanisms of neuropsychiatric disorders, facilitating the development of potent treatments.

Project Abstract Our project aims to form a multi-site consortium that will carry out fundamental exper- iments to elucidate the mesoscopic and microscopic neural dynamics underlying human memory and use direct brain stimulation as a manipulative tool to study those dynamics. Additionally, we seek to create a dynamical timeseries model that predicts the evolution of brain activity during cognitive tasks and incorporates the e ects of stimulation-induced perturbations on the system.

PROJECT SUMMARY The thalamic reticular nucleus (TRN), the major source of thalamic inhibition, plays essential roles in sensory processing, arousal and cognition. Receiving inputs from cortical and subcortical regions, this structure is strategically positioned to influence thalamo-cortical interactions. During quiescence, the TRN participate in sleep rhythm generation, sleep stability and memory consolidation, while in active states, TRN neurons contribute to sensory filtering underlying attention.

NEURONAL CIRCUITS FOR CONTEXT-DRIVEN BIAS IN AUDITORY CATEGORIZATION In everyday life, because both sensory signals and neuronal responses are noisy, important cognitive tasks, such as auditory categorization, are based on uncertain information. To overcome this limitation, listeners incorporate other types of signals, such as the statistics of sounds over short and long time scales and signals from other sensory modalities into their categorization decision processes. At the behavioral level, such contextual signals bias categorization by shifting the listener's psychometric curve.

Project Summary/Abstract Speech perception is inherently multisensory: when conversing with someone that we can see, our brains combine auditory information from the voice with visual information from the face. Speech perception lies at the heart of our interactions with other people and is thus one of our most important cognitive abilities. However, there is a large gap in our knowledge about this uniquely human skill because most experimental techniques available in humans suffer from poor spatiotemporal resolution.