An AC constant-response method for electrophysiological measurements of spectral sensitivity functions.
A number of methods have been used in the past to measure spectral sensitivity (S(lambda)) functions of electric responses in the visual system. We present here a microcomputer based, AC, constant-response method for automatic on-line measurement of S(lambda) in cells with or without a sustained tonic response. It is based on feedback adjustment of light intensity to obtain constant peak-to-peak amplitudes of response to a flickering stimulus as the spectrum is scanned between 300 and 700 nm in 4 nm steps. It combines the advantages of: (1) on-line presentation of S(lambda) curves; (2) constant light adaptation; (3) sampling of many points; and (4) fast data collection time. The system can be applied to sensitivity or threshold (e.g., S(lambda), dark adaptation, receptive field) measurements of any electrically recorded visual response.
Department of Experimental Psychology, University of São Peulo, Brazil. johns@usp.br
J M
JM
de Souza
R D
RD
DeVoe
C
C
Schoeps
D F
DF
Ventura
D000818:Animals; D001516:Bees; D010786:Photoreceptor Cells / Q000502:physiology*; D012680:Sensitivity and Specificity; D014793:Visual Cortex / Q000502:physiology*