The auditory cortex is a highly organized processing unit for sound in the brain. A variety of in vivo studies have shown that tuning curves can be modified with clear “learning-related” or activity dependent plasticity. I am interested in studying the cellular actions of neuromodulators on the primary auditory cortex with the assumption that this will provide us with cellular mechanisms that could explain the actions described in vivo. I am also investigating the role of the neurotransmitter acetylcholine (ACh), and given the interest of our lab I want to investigate the actions of certain neuropeptides on neuronal excitability as well. Increased activity within the nucleus basalis, an ACh-containing nucleus whose activity is related to learning processes and innervates the neocortex, can modulate tuning curve characteristics in primary auditory cortex. Despite clear evidence of the overall effect of ACh on receptive field properties, the underlying cellular mechanisms are unclear and will be a focus of my research. Thus, the immediate focus of my project is to carry out experiments to answer the question: How do ACh and other neuromodulators influence synaptic transmission in primary auditory cortex? In a different but related line of research, the primary auditory cortex receives thalamic input from the medial geniculate nucleus (MGN) of the thalamus. The MGN is divided in two pathways: magnocellular MGN (mMGN) which innervates neocortical layer IV, and ventral MGN (vMGN) which projects to layer I/II. The mMGN has traditionally been considered a “non-plastic” pathway, whereas the vMGN has been thought to be a plastic or modulatory pathway; however, this hypothesis has not been tested at the cellular level. I am testing how these two pathways converge and sculpt synaptic activity within the primary auditory cortex.