Saccade correlated potentials in optic tectum and cerebellum of Carassius auratus

Abstract

Summaryo(1)In the encéphale isolé goldfish, Carassius auratus, when recording in the dark adapted state, 50–200 msec after the onset of a conjugate eye saccade, a predominately negative potential, 150–200 msec in duration, with peak amplitudes ranging from 100 to 500 μV, appears over the lateral two-thirds of the optic tectum.(2)Recording at successive depths, the negative wave decreases in amplitude, disappearing at a depth of ∼500–750 μm. A positive going potential emerges at depths of 1000–1250 μm, whose peak corresponds in time to the superficial negative wave peak; it originates in the valvula.(3)Potentials in the optic tectum evoked by saccadic eye movement in the light show shorter latency, more uniform, multiphasic waveform and absence of detectable potentials in the surface to ∼300 μm levels of the tectal layers.(4)Stretch of the abducens eye muscle can produce a 5–10 msec latency, negative going wave in the contralateral tectum. Transection of all eye muscles of the globe reduces the amplitude of TSEP largely in the ipsilateral tectum, without change in waveform or timing. Also, saccadic movements of the opposite eye increase in amplitude.(5)The midline valvula of the cerebellum exhibits a pre-saccadic, positive going 200–600 μV slow wave. High amplitude slow potentials, starting before the saccade, occur 1200 μm beneath the valvula surface.(6)Mechanical distortion of the globe failed to produce any of these phenomena. In the encéphale isolé goldfish, Carassius auratus, when recording in the dark adapted state, 50–200 msec after the onset of a conjugate eye saccade, a predominately negative potential, 150–200 msec in duration, with peak amplitudes ranging from 100 to 500 μV, appears over the lateral two-thirds of the optic tectum. Recording at successive depths, the negative wave decreases in amplitude, disappearing at a depth of ∼500–750 μm. A positive going potential emerges at depths of 1000–1250 μm, whose peak corresponds in time to the superficial negative wave peak; it originates in the valvula. Potentials in the optic tectum evoked by saccadic eye movement in the light show shorter latency, more uniform, multiphasic waveform and absence of detectable potentials in the surface to ∼300 μm levels of the tectal layers. Stretch of the abducens eye muscle can produce a 5–10 msec latency, negative going wave in the contralateral tectum. Transection of all eye muscles of the globe reduces the amplitude of TSEP largely in the ipsilateral tectum, without change in waveform or timing. Also, saccadic movements of the opposite eye increase in amplitude. The midline valvula of the cerebellum exhibits a pre-saccadic, positive going 200–600 μV slow wave. High amplitude slow potentials, starting before the saccade, occur 1200 μm beneath the valvula surface. Mechanical distortion of the globe failed to produce any of these phenomena.