Light response differences in the superior colliculus of albino and pigmented rats

Abstract

Light response differences in the superior colliculus of albino and pigmented rats AbstractMulti-unit visual responses to light intensities ranging from −6.46 to 0.81 log cd/m 2 were recorded from the surface of the superior colliculus of dark-adapted normal pigmented and normal albino rats. Light sensitivity was significantly higher in albinos. The response onset latency was inversely proportional to the stimulus intensity. The progression of the stimulus intensity versus response onset latency curve showed a considerable difference between pigmented and albino rats. At low light levels, longer response onset latencies were recorded in pigmented rats than in albinos. This can be attributed to the transmission of rod-driven responses. The differences observed in the light response characteristics of albino rats may be indicative of their visual abnormalities.

Rat strain differences in startle gating-disruptive effects of apomorphine occur with both acoustic and visual prepulses

“…Nonetheless, we note that, compared to albino SD rats, pigmented LE rats exhibited less PPI in response to visual prepulses for all prepulse durations. This observation is consistent with reports of greater sensitivity to photic stimulation within the superior colliculus in albino vs. pigmented rats (Thomas et al, 2005).…”

Comparison of visual function in pigmented and albino rats by electroretinography and visual evoked potentials

“…Thomas et al [48] speculated that the longer rod-driven latencies in pigmented rats could be a manifestation of the inhibitory GABA system because GABA is presumably involved in rod-driven visual signals [34,38]. Furthermore, enhanced GABA in Long-Evans rat retinas could also contribute to the higher post-receptoral response found in our study.…”

“…Thomas et al [48] performed a different kind of investigation by recording multi-unit visual responses from the surface of the superior colliculus of albino and pigmented rats. In contrast to most of the other work in this field, they found a lower dark-adapted visual threshold in albino rats.…”

Behavioral evaluation of visual function of rats using a visual discrimination apparatus

“…The threshold luminance level of normal pigmented rats was found to be −5.37 ± 0.05 log cd/m 2 , an even lower threshold level than that obtained by direct electrophysiological recording from the visual center (SC) of the brain (−5.25 log cd/m 2 ) (Thomas et al, 2005). However, it should be noted that the SC visual responses were measured during fullfield light stimulation, whereas black and white stripes were used for behavioral visual stimulation in the visual discrimination apparatus.…”