Optical recording of membrane potential responses from early embryonic XXXX ganglia using voltage-sensitive dyes.

@entity2085 @entity1022 @entity4524 @entity60028 @entity1573 @entity972 @entity28859
Changes in absorbance of voltage-sensitive @entity28859 - @entity60028 dyes were used to monitor electrical responses in the semilunar ganglion of 4-10-day-old developing @entity1573 embryos. The electrical responses were simultaneously recorded from many positions in the ganglion. Stimulation of the afferent nerve fibers (the ophthalmic division of cranial nerve V) with a suction electrode led to changes in light absorption of the stained ganglia. With both the depolarizing and hyperpolarizing pulses, the change was largest at 700 nm and was eliminated at a wavelength of 620 nm where the voltage-dependent absorption change of the dyes disappears. In the 4-10-day-old @entity2085 , two types of optical membrane potential responses, 'non-conducted' and 'conducted' responses, were identified. The non-conducted response varied with the intensity of the stimulus and had the nature of an electrotonic spread. Furthermore, this non-conducted response exhibited an 'initial upstroke-response' followed by the steady-state plateau evoked by larger depolarizing pulses. The conducted responses were blocked by @entity1022 ( @entity4524 ) or by high external @entity972 concentration. The incidence of the conducted responses increased as development proceeded from the 5th to the 10th day of age. Thus, the @entity4524 -sensitive action potential activity is probably generated initially in the semilunar ganglion during the 5-10-day-stage of development. These data represent the first demonstration of membrane potential responses in early embryonic intact nervous system. Furthermore, these studies demonstrate the usefulness of voltage-sensitive dyes in the analysis of the organizing process of embryonic neuronal functions during these early stages of development.
