Mjm. Lankheet et al., SPATIAL AND TEMPORAL PROPERTIES OF CAT HORIZONTAL CELLS AFTER PROLONGED DARK-ADAPTATION, Vision research, 36(24), 1996, pp. 3955-3967
We studied the change of spatial and temporal response properties for
cat horizontal (H-) cells during prolonged dark adaptation. H-cell res
ponses were recorded intracellularly in the optically intact, in vivo
eye, Spatial and temporal properties were first measured for light-ada
pted H-cells, followed by a period of dark adaptation, after which the
same measurements were repeated, During dark adaptation threshold sen
sitivity was measured at regular intervals, Stable, long lasting recor
dings allowed us to measure changes of sensitivity and receptive field
characteristics for adaptation periods up to 45 min. Although cat H-c
ells showed no signs of dark suppression or light sensitization, they
remained insensitive in the scotopic range, even after prolonged dark
adaptation, Absolute thresholds were in the low mesopic range. The sen
sitization was brought about by a shift from cone to rod input, and by
substantial increases of both spatial and temporal integration upon d
ark adaptation. The length constant in the light-adapted state was on
average about 4 deg, After dark adaptation it was up to a factor of th
ree larger, with a median ratio of 1.85. Response delays, latencies an
d durations for (equal amplitude) threshold flash responses substantia
lly increased during dark adaptation. Copyright (C) 1996 Elsevier Scie
nce Ltd