Effects
of drug-state changes upon starting and running responses in a
straight runway in shock-motivated rats
S. Iwahara & T. Takahashi |
Rats
were run 20 trials per day for 10 days, in the straight runway, shock
being administered from the floor if they failed to enter the safe
goal box within 5 sec. Half the rats were given either saline or
20 mg/kg, i.p, of CDP, 30 min prior to daily trials for Days 1 to
4. (L1), half of each group were shifted their drug state from L1
to L2 (Days 5 to 7), and finally half of the rats in each subgroup
were shifted their drug state from L2 to L3 (Days 8-10). Both starting
time (ST) and running time (RT) were increased by CDP and only ST
was state-dependent. In addition, ST tended to decrease if drug state
was shifted in L3 back to the original state in L1. The facts that
only ST showed ordinary learning curves and it was not correlated
with RT, suggested that only those responses which are shown to be
conditionable may be state-dependent.
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