Avoidance performance, cue and response-choice discrimination after neuroleptic treatment

Effects of pimozide, across doses and within sessions, on discriminated lever release performance in rats

“…In operant paradigms, neuroleptic treatment has been shown to increase lever press duration Fowler et al 1986a) and lick duration (Gramling et al 1984), findings which are congruent with the results reported here. In addition, the increased proportion of extended responses resulting from pimozide treatment is consistent with studies that interpret the failure of neuroleptic treated rats to make avoidance responses to be due to a reduced ability to initiate voluntary motor behavior (Posluns 1962;Anisman et al 1982); i.e., failure to initiate a response and failure to release the lever on cue may be manifestations of the same underlying mechanism. In the DLR task, the rat initiates a trial by depressing the lever, but it must also "initiate" a release.…”

“…This initiation deficit hypothesis is consistent with findings from catalepsy tests, where neuroleptics ar e thought to amplify postural support reflexes (DeRyck et al 1980;Wolgin 1985;Pellis et al 1986), from appetitive free operant paradigms, where neuroleptics increase operant response duration (Fowler 1974;Gramling et al 1984;Fowler et al 1986a, b), and Offprint requests to: S.C. Fowler from experiments on discriminated active avoidance (DAA), where neuroleptics attenuate avoidance responding while leaving escape responding largely intact (Posluns 1962;Cook and Catania 1964;Fibiger et al 1975;Anisman et al 1982). Moreover, in the case of DAA, several studies appear to rule out the possibility that neuroleptic-induced performance deficits are the result of difficulties in the animal's processing of stimulus-stimulus associations (Posluns 1962;Beninger et al 1980;Anisman et al 1982), thereby strengthening the initiation deficit hypothesis.…”

Response decrement patterns after neuroleptic and non-neuroleptic drugs

“…A number of researchers have suggested that the effects of neuroleptic drugs on avoidance behaviour may be due to a drug-induced interference with the capacity to initiate responses (Anisman et al 1982;Beninger et al 1980;Fibiger et al 1975;Posluns 1962) and it has also been proposed that such a mechanism may account for the effects of these drugs on water reinforced responding (Fowler et al 1984). The present results suggest that this cannot provide a complete explanation because, should neuroleptics simply interfere with motor control mechanisms, there seems no reason to suppose that responding would be unaffected on the first trial but completely blocked later in a session unless it is proposed that these drugs might induce fatigue in the response initiation process.…”

“…Most studies of the mechanisms by which neuroleptics interfere with avoidance behaviour have emphasised motor processes and, in particular, the ability of drugged animals to initiate responses (Anisman et al 1982;Beninger et al 1980;Fibiger etal. 1975;Posluns 1962).…”

Scopolamine attenuates the motor disruptions but not the attentional disturbances induced by haloperidol in a sustained attention task in the rat

“…In addition, it is important to note that rats trained to perform choice tasks, without a sustained attention requirement, do not show evidence of disrupted discriminative capabilities (Tombaugh et al 1980;Anisman et at. 1982).…”