Memory and perseveration on a win-stay, lose-shift task in rats exposed neonatally to alcohol.

OBJECTIVE

It is important to understand the relationship between perseverative responding resulting from perinatal exposure to alcohol and potential underlying causes, including attention, memory, or response-inhibition problems. The present study was designed to examine the relationship between perseveration and memory.

METHOD

Rats exposed neonatally to 6 g/kg/day alcohol from postnatal day (PD) 4 through PD 9 using an artificial rearing technique (n = 8) were compared with an artificially reared gastrostomy control group (n = 8) and a suckle control group (n = 8). Activity levels were assessed from PD 18-21. Beginning on PD 45, subjects were deprived of food and responded for food on a two-lever win-stay, lose-shift task in which reinforcement probability was a function of reinforcement delivery on the previous trial. If reinforcement was delivered, only a response on the same lever (stay) was reinforced. If reinforcement was not delivered, only a response on the opposite lever (shift) was reinforced. Effective responding depended on subjects remembering whether a reinforcer was delivered on the preceding trial. The intertrial interval varied across conditions (5 seconds or 60 seconds).

RESULTS

Alcohol-exposed rats showed increased activity during activity testing but did not differ from controls on win-stay, lose-shift accuracy. All groups showed a performance decrease at longer intertrial intervals. Alcohol-exposed rats showed increased lever pressing during the intertrial interval compared with suckle control rats but not with gastrostomy control rats.

CONCLUSIONS

Choice behavior was comparable for all groups on the win-stay, lose-shift task, indicating that memory, as assessed by this task, was not differentially affected by alcohol exposure. Alcohol-exposed rats responded more during the intertrial interval compared with suckle controls, suggesting increased activity without increased response inhibition. The win-stay, lose-shift procedure is a potentially useful tool for separating simple activity level effects, memory-related effects, and response-inhibition effects. This study also highlights the need for additional research describing the relationship between perseverative responding and underlying mechanisms.