Neural plasticity occurs in the auditory neocortex, and is thought to underlie some forms of learning. The goal of Dr. Metherate's research is to understand the cellular bases of neural plasticity. Neural plasticity is proposed to depend on the interactions between auditory and neuromodulatory inputs to cortical nerve cells. Auditory information is delivered via projections from the auditory thalamus. This information is then modified by inputs from neuromodulatory systems to produce neural plasticity. Dr. Metherate proposes the following mechanism: primary auditory inputs, which contact close to the cell bodies of cortical neurons, exert a strong influence over neuronal activity. While secondary auditory inputs relay plasticity information to distant parts of cortical neurons, and exert less influence over neuronal activity at the cell body. Modulation of cortical neurons makes them electrically more "compact". This allows the secondary inputs to "reach" the cell body, facilitating the integration of primary and secondary inputs, and lowering the threshold for plasticity to occur. In this study, Dr. Metherate will record the activity elicited by primary inputs to determine the threshold for one form of plasticity called long-term potentiation (LTP). He will examine modulation of neural activity, responses to secondary inputs, and LTP threshold by stimulating two kinds of neuromodulatory inputs: those from the nucleus basalis and locus coeruleus. This exciting project will advance the study of cortical plasticity by determining how parallel auditory pathways converge and interact at the cortex, and how neuromodulatory systems regulate auditory information processing. Dr. Metherate's research is an important model which has intuitive appeal in terms of cortical circuitry and in relation to memory and other cognitive disorders such as Alzheimer's disease.***//
