Research Interests

The mesolimbic dopamine system is the neural substrate for the human cognitive processes of reward, reinforcement and motivation. Exactly how the cells and circuits of this system function together to give rise to these processes is poorly understood. My research focuses on how various forms of synaptic transmission within and between the brain areas of the mesolimbic system are regulated and modulated, under both normal and pathological conditions like drug addiction, alcoholism and schizophrenia. To that end, I study the cellular and synaptic physiology of neurons in the ventral tegmental area and the nucleus accumbens. I use simultaneous paired whole-cell patch-clamp recording in acute brain slices to examine circuit and synaptic connectivity along with iontophoresis and single channel electrophysiology to investigate particular neurotransmitter receptors and ion channels. My current experiments are focused on the interactions between various neurotransmitters in the nucleus accumbens to understand more precisely how they influence neuronal excitability and information processing in the forebrain. This will lead to a more complete understanding of the neural basis of reward, reinforcement and motivation, and may also give us some insight into how these processes contribute to the cognitive nature of human brain.

Publications

Cui G, Bernier BE, Harnett MT, Morikawa H (2007). Differential regulation of action potential- and metabotropic glutamate receptor-induced Ca2+ signals by inositol 1,4,5-trisphosphate in dopamine neurons. J Neurosci 27(17): 4776-85. PubMed

Ponomarev I, Maiya R, Harnett MT, Schafer GL, Ryabinin AE, Blednov YA, Morikawa H, Boehm SL II, Homanics GE, Berman A, Lodowski KH, Bergeson SE, Harris RA (2006). Transcriptional signatures of cellular plasticity in mice lacking the α1 subunit of GABAA receptors. J Neurosci 26: 5673-5683. PubMed

Okamoto T, Harnett MT, Morikawa H (2006). Hyperpolarization-activated cation current (Ih) is an ethanol target in dopamine neurons of mice. J Neurophysiol 95: 619-626. PubMed

Boland LM, Jiang M, Lee SY, Fahrenkrug SC, Harnett MT, O'Grady SM (2003). Functional properties of a brain-specific N-terminally spliced modulator of Kv4 channels. Am J Physiol Cell Physiol 285(1): C161-70.