Perceptual Learning in the Sensory Cortex: Circuit Dynamics and Regulation

Funding Round: 2 2014-2016

Research Question: Learning new skills depend on changes in the underlying neural activity, and in many cases, are improved by active engagement of the learner. What large-scale changes in cortical encoding underlie perceptual learning? How does norepinephrine, a key neuromodulator involved in cognitive alertness, influence cortical circuits to promote perceptual learning?

Interdisciplinary Approach: This project will use behavioral measurements in actively learning animals, cellular-resolution monitoring of neurons, and mechanistic intracellular analysis in brain slices to better understand the neural circuit basis of perceptual learning.

Potential Implications of Research: Our experiments will advance the science of learning toward an integrated view of the neurobiological basis of perceptual learning. Project results may facilitate development of methods for improving learning by directed manipulations of neuromodulatory systems in normal and diseased brains.

Project Description:  Perceptual learning is the progressive improvement of skill in performing a sensory task that occurs through practice. Perceptual learning occurs throughout the life of an organism and is thought to involve changes in the structure and function of neurons in the sensory cortex. This essential form of learning depends on active engagement from the learner, but the underlying neurobiology remains unclear. Norepinephrine released from locus coeruleus neurons is thought to enhance sensory processing by modulating the transfer of information through cortical circuits. Drugs that modulate norepinephrine, such as methylphenidate (e.g., Ritalin), a first-line therapy for Attention Deficit Hyperactivity Disorder (ADHD), further suggest that norepinephrine may play a role in effective learning. However, the mechanisms by which norepinephrine may regulate perceptual learning are not well understood.

Our project will investigate the role of norepinephrine in modulating cortical responses (Fig. 1) during a perceptual learning task and identify the underlying neuronal circuits and cell types that generate these responses. First, we will ask how two different populations of pyramidal neurons change their response properties during perceptual learning. Second, we will determine the responses of locus coeruleus neurons, the major source of norepinephrine in the central nervous system, during this task and ask how their activity patterns change during perceptual learning (Fig. 2). Third, we will quantify the responses of these two populations of cortical neurons to norepinephrine in vitro and investigate the underlying cellular mechanisms. These experiments will help provide an integrated view of how perceptual learning arises from changes in sensory cortical dynamics under the regulation of the brain’s norepinephrine system.