"Regional heterogeneity of dopamine neuron transmission in the striatum" Dr. Nao Chuhma

Dr. Nao Chuhma

Associate Research Scientist/ Research Scientist

Psychiatry/ Molecular Therapeutics

Columbia University/ New York State Psychiatric Institute

Abstract

The striatum is the input nucleus in the basal ganglia and the major projection site of dopamine neurons in the ventral midbrain. Recent studies of ventral midbrain dopamine neurons and the striatum revealed that categorizing the striatum as ventral (nucleus accumbens) and the dorsal segments is too simplistic and does not accurately reflect the functional diversity of the striatum. Adding to this complexity, dopamine neurons are now known to corelease glutamate and GABA, which may add further regional heterogeneity to dopamine neuron transmission. Though it is likely that dopamine neurons transmit different signals among functionally different subregions, systematic studies of dopamine neuron synaptic connections among subregions of the striatum were sparse. To elucidate region-specific dopamine neuron transmission, I have studied fast and direct synaptic connections of ventral midbrain dopamine neurons to the striatum on identified populations of neurons in each subregion with optogenetic stimulation. Region specific recording from identified striatal neurons revealed a striking regional heterogeneity with differential blend of three transmitters released from dopamine neurons; dopamine, GABA and glutamate, novel synaptic responses and coiregionally different modulation of synaptic transmission. This study will be the first step of identifying the functional connectivity of dopamine neurons in their major projection area, providing the basic information for further studies of the microcircuitry underpinning functional diversity of the striatum.

Biography

Dr. Nao Chuhma received her MD in March 1994 from Kyoto University Faculty of Medicine, School of Medicine. She proceeded to Kyoto University Graduate School of Medicine in neuroscience. During graduate school, she studied postnatal development of high-fidelity fast synaptic transmission in the timing-coding pathway of the auditory brainstem in rats. She received her PhD in March 1998. After graduate training, she became interested in neuronal circuitry more directly relevant to neuropsychiatric disorders. In 2001, she joined the laboratory of Dr. Stephen Rayport in Columbia University, Department of Psychiatry as a post-doctoral research fellow to study dopamine neuron synaptic transmission, and showed glutamate cotransmission of dopamine neurons in the nucleus accumbens in brain slices. She was appointed to Associate Research Scientist in 2003 and Research Scientist in New York State Psychiatric Institute in 2005. She is currently working on synapse physiology in the basal ganglia, particularly in dopamine neurons and their projections.