STRUCTURAL BASIS OF AMBLYOPIA & STRABISMUS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: Transmission of Burst Firing at the Retinogeniculate Synapse: In the visual system, output from the retina is filtered through a thalamic relay station called the lateral geniculate nucleus (LGN) before transmission to the cortex. The probability that a given retinal action potential generates an action potential in a geniculate neuron is usually much less than 100%. It is possible, however, for a single retinal spike to generate more than one geniculate spike, because LGN firing behavior exists in two modes: tonic and burst. Burst spikes are defined as those occurring after a 100 ms pause, with an interspike interval of less than 4 ms. During the silent period, the low-threshold Ca2+ current (IT) becomes de-inactivated. Subsequently, a single retinal EPSP can cause a burst of geniculate action potentials riding on a large depolarizing Ca2+ current. We tested what happens to efficacy when an LGN neuron fires in burst mode, rather than tonic mode, during natural stimulation.