Neural correlates of motion after-effects in cat striate cortical neurones: monocular adaptation.
Motion after-effects were elicited from striate cortical cells in lightly-anaesthetized cats, by adapting with square-wave gratings or randomly textured fields drifting steadily and continuously in preferred or null directions. The time-course and recovery of responsiveness following adaptation were assessed with moving bars, gratings or textured fields. Results were compared with controls in which the adapting stimulus was replaced by a uniform field of identical mean luminance, and also assessed in relation to the strength and time course of adaptation. Within 30-60 s adaptation, firing declined to a steady-state. Induced after-effects were direction-specific, and manifest as a transitory depression in response to the direction of prior adaptation, recovering to control levels in 30-60 s. Maximal after-effects were induced by gratings of optimal drift velocity and spatial frequency. With rare exceptions after-effects were restricted to driven activity; no consistent effects on resting discharge were observed. The onset of adaptation, and the recovery period, were more rapid in simple cells, although after-effects of comparable strength were elicited from simple and from standard complex cells. Special complex cells, including many of the more profoundly texture-sensitive neurones in the cortex, were more resistant to adaptation. The results support the conclusion that psychophysically measured adaptation and induced motion after-effect phenomena reflect the known properties of cortical neurones.
Hammond
P
P
Department of Communication and Neuroscience, University of Keele, Staffordshire, U.K.
Mouat
G S
GS
Smith
A T
AT
D000818:Animals; D002415:Cats; D005074:Evoked Potentials, Visual; D007839:Functional Laterality / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000502:physiology; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology