Spine Specific Targeting of Ion Channels in Striatal Neurons. (360G-Wellcome-092200_Z_10_Z)

My goal is to understand the cellular and molecular organisation of synaptic inputs onto MSNs in the striatum. First, I will use in vivo viral infection to express light-activated ion channels (channelrhodopsins) in functionally distinct brain areas that project to the striatum. I will use whole-cell recording to measure the physiological properties of MSNs in acute slices from these animals. Filling these neurons with morphological markers and calcium- sensitive dyes will enable me to visualise both dendrites and spines using 2-photon microscopy. I will then trigger synaptic transmission by illuminating channelrhodopsin-containing pre-synaptic inputs at specific dendritic locations. By measuring evoked fluorescence transients and exploiting selective pharmacology, I will determine where on the dendrites different inputs form synapses, and which glutamate receptors contribute to their spine calcium signals. Second, I will determine how these specific sets of glutamate receptors are targ eted to particular postsynaptic locations. I will use molecular approaches, including dominant negative expression constructs and synthetic peptides, to interfere with protein interactions controlling receptor trafficking. Receptor function will be assessed using electrophysiology and imaging, and quantum dot single-particle tracking will be used to investigate the lateral mobility and synaptic targeting of proteins.