Non-lateralization of a temporal discrimination task acquired under unilateral cortical spreading depression

Forty-nine rats were trained for three days to obtain water from a drinking tube for every 15th lick. On the next day 44 of them learned under unilateral cortical spreading depression to lick for differential reinforcement of low rates of responding (minimum interlick interval 6 sec - DRL 6). On day 5 the DRL 6 task was retrained with either the contralateral (n = 32) or ipsilateral (n = 12) cortical hemisphere depressed. Five rats served as unoperated controls. In all three groups DRL performance was significantly improved on day 5. The failure to achieve DRL lateralization by functional hemidecortication suggests that DRL responding has a strong non-neocortical component.