Synaptic Physiology Section
Dr. Diamond received his B.S. from Duke University in 1989 and his Ph.D. from the University of California, San Francisco in 1994, where he studied excitatory synaptic transmission in the retina with David Copenhagen. During a postdoctoral fellowship with Craig Jahr at the Vollum Institute, he investigated the effects of glutamate transporters on excitatory synaptic transmission in the hippocampus. Dr. Diamond joined NINDS as an investigator in 1999, was awarded the Presidential Early Career Award in Science and Engineering in 2000 and was promoted to Senior Investigator in 2007. His laboratory studies how synapses, neurons and small circuits perform computational tasks required for visual information processing in the mammalian retina.
Synapses mediate communication between neurons in the CNS. We have learned a great deal about the structural and molecular organization of these specialized contacts, but many important physiological questions remain unresolved. How do the morphological characteristics of the synaptic cleft and the biophysical properties of neurotransmitter receptors influence synaptic signaling? How do transporters, which bind free neurotransmitter and remove it from the extracellular space, limit the extent to which it diffuses from its point of release? Can neurotransmitter diffuse out of the synaptic cleft to activate receptors in neighboring synapses and, if so, how does this "spillover" degrade or enhance the information capacity of a neuronal network? How are these processes developmentally regulated? In the hippocampus, answers to these questions may give insight into the mechanisms by which learning and memory are implemented at the synaptic level. In the retina, they may help explain how visual information is transformed into a neural code and how the visual system's exquisite sensitivity and spatial acuity is preserved. We approach these questions experimentally using electrophysiological and imaging methods in hippocampal and retinal slice preparations.
Download data acquisition software used in the laboratory.
Reciprocal Synapses in the Retina
This figure shows a rendered three-dimensional EM reconstruction of a reciprocal synapse in the mammalian retina. Rod bipolar cells (RBC,orange) make excitatory, ribbon-type synapses onto A2 (purple) and A17 (red) amacrine cells. A2s relay the rod bipolar signal to the cone pathway, and A17s regulate this process through reciprocal GABAergic synapses back onto the RBC terminal. The three-dimensional reconstructions revealed (right panel) that each A17 synaptic varicosity receives one excitatory synapse (blue sphere) and returns two reciprocal inhibitory synapses (yellow sphere). Recent work in the lab has shown how the A17 transforms the excitatory input into inhibitory feedback and how hundreds of these individual feedback microcircuits operate independently within a single A17. For details, see Grimes, et al. (2010).
Dr. Cole Graydon, Ph.D.
Ms. Katie Kruk, B.S.
Post baccalaureate IRTA Fellow
Dr. Alon Poleg-Polsky, Ph.D.
Dr. Miloslav Sedlacek, Ph.D.
Ms. Hua Tian, B.S.
Dr. Jun Zhang, Ph.D.