Imaging postsynaptic activities of teleost thalamic neurons at single cellresolution using a voltage-sensitive dye

Optical recording of neuronal activities using voltage-sensitive dyes (VSDs ) is a useful method for simultaneous multisite recording. However, it has been rather difficult to distinguish optical signals from individual, ident ified cells. We applied the optical recording technique using a high-speed charge coupled device (CCD) imaging system to a teleost thalamic nucleus, c orpus glomerulosum (CG) which has a well-defined histological organization and large postsynaptic dendrites. Patch-like dye (di-4-ANEPPS) signals were observed in the dendritic layer of the CG in response to afferent nerve st imulations. These responses were completely blocked by an alpha -amino-3-hy droxy-5-methyl-4-isoxazole-proprionate (AMPA) receptor antagonist, did not propagate, and the size of the patches were close to that of a single dendr itic tip of the 'large cell'. Thus, we found that these patch-like VSD sign als most likely represent postsynaptic potentials at individual dendritic t ips of the large cells. (C) 2001 Elsevier Science Ireland Ltd. All rights r eserved.