Amnesia for discrete events in rats with fornicotomies: effects of interference on spatial alternation performance.

Rats, one groups with fornicotomies, and another group with control operations, were trained in several versions of a bar-press, spatial alternation task. In free operant conditions the fornicotomized rats showed adequate alternation performance when the bars were relatively separated by placement either at the ends of an alley or at the ends of the arms of a T-maze, but they were impaired when the bars were adjacent. Also, the fornicotomized rats failed to alternate after interpolation of either baffles or a 10-sec delay in the stem, both of which manipulations resulted in intervening turning responses before each choice. A failure to discriminate memories of relevant, discrete events from those of similar, intervening events appears best to account for the results.