Principal Investigator: Carlos D Brody
Princeton Neuroscience Institute
Title: “Mechanisms of neural circuit dynamics in working memory”
BRAIN Category: Understanding Neural Circuits (RFA NS-14-009)
Dr. Brody and his colleagues will study the underlying neuronal circuitry that contributes to short-term “working” memory, using tools to record circuit activity across many brain areas simultaneously while rodents run on a track-ball through virtual mazes projected onto a screen.
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Figure: A decision-making task requiring accumulation of evidence over time. The capacity to gradually and steadily accumulate evidence favoring one choice or another is thought to be a core component of many different types of decision-making. In order to establish a rodent model of this cognitive process, we developed a task in which subjects hear simultaneously presented trains of randomly timed clicks, one train coming from a speaker to their left, the other from a speaker to their right. At the end of the trains, the subjects have to decide which side played the greater total number of clicks. We were able to train rats to perform this task, and to show that well-trained animals use a strategy of accumulating clicks over time. Having established a behavior that depends on gradual accumulation of sensory evidence, we are now using electrophysiological, pharmacological, optogenetic, and computational approaches to determine the neural basis of this cognitive process. From Brunton, B.W., Botvinick, M.M., and Brody C.D. 2013. Science 340:95–98.
Project Description
Working memory, the ability to temporarily hold multiple pieces of information for mental manipulation, is central to virtually all cognitive abiliies. Working memory has been closely associated with multiple kinds of neural activity dynamics, such as persistent neural activity, activity ramps, and activity sequences. The neural circuit mechanisms of these dynamics remain unclear. This proposal will apply advanced technologies such as virtual reality, automated monitoring of behavior, in vivo microscopy, ontogenetic, and neural circuit reconstruction to solve fundamental problems in the understanding of working memory. The accumulation of evidence over time scales of seconds, a type of working memory critical for decision-making, will be used as a test bed for studying working memory. The proposal will build upon a rodent evidence-accumulation paradigm that allows quantitative, temporally precise parameterization of working memory and decision-making. The paradigm will be implemented with head-fixed rodents behaving in a virtual reality system (Aim 1), providing mechanical stability that enables the use of two-photon calcium imaging to observe neural activity related to working memory in the neocortex, basal ganglia, and cerebellum (Aim 3). Brain activity will also be perturbed using ontogenetic to probe the roles of brain regions and specific cell types in the formation and stabilization of memory (Aim 2). Finally, we will develop methods for probing the roles of cell types and connectivity in working memory through correlative serial electron microscopy and light microscopy as well as imaging of population responses to ontogenetic stimulation of single cells or groups of cells (Aim 4). This three-year project will produce a catalog of the types of neural circuit dynamics that are related to working memory across many brain regions. In subsequent years, this catalog will be mechanistically investigated by the anatomical and physiological methods developed in Aim 4. The long-term goal of this project is to arrive at a complete, brain-wide understanding of the cellular and circut mechanisms of activity dynamics related to working memory. The understanding is expected to take the form of a new generation of models containing cognitive variables distributed across brain regions, as well as models that explicitly represent neural circuit dynamics. This achievement will be a crucial step towards a mechanistic understanding of the neural basis of cognition.
Public Health Relevance Statement
Working memory, the ability to temporarily hold multiple pieces of information for mental manipulation, is central to virtually all cognitive abilities and s disrupted in diseases such as schizophrenia. The long-term goals of this project are to characterize neural activity dynamics related to working memory in diverse brain regions, and to account for those dynamics in an integrated, brain-wide fashion in terms of cellular and circuit mechanisms. These goals will be achieved by observing, mapping, and perturbing brain circuits using advanced technologies which will be disseminated to the entire neuroscience community to accelerate progress towards understanding brain function and dysfunction.
NIH Spending Category
Basic Behavioral and Social Science; Behavioral and Social Science; Bioengineering; Neurosciences
Project Terms
Accounting; Achievement; Algorithms; Anatomy; Animal Model; Animals; awake; Basal Ganglia; base; Beds; Behavior; Behavior monitoring; Behavioral; Behavioral Model; Brain; Brain region; Breathing; Calcium; Cataloging; Catalogs; cell type; Cells; Cerebellum; Cognition; Cognitive; Communities; Complex; Data; Decision Making; Disease; Dopamine; Electron Microscopy; Foundations; Functional disorder; Future; Generations; Goals; Head; Image; improved; in vivo; Lead; light microscopy; Machine Learning; Maintenance; Maps; Mechanics; Memory; Methods; Microscopy; Modeling; Molecular Probes; Monitor; Neocortex; neural circuit; Neurons; Neurosciences; nonhuman primate; novel; optic imaging; Optics; optogenetics; Physics; Physiological; Play; Population; Property; Psyche structure; public health relevance; Ramp; reconstruction; relating to nervous system; Reporting; Resolution; response; Rodent; Role; Schizophrenia; Sensory Process; Short-Term Memory; social; System; Technology; Testing; theories; Time; tool; Training; two-photon; virtual reality; Whole-Cell Recordings