Role of retroactive interference in the spatial memory of normal rats and rats with hippocampal lesions.

Abstract

The importance of retroactive interference (RI) in memory for spatial locations was studied by using a 12-arm radial maze and a standard RI paradigm. Animals in the RI condition first learned to choose 4 of the 12 arms, followed by training to a second set of 4 arms. In the control condition for interference, rats learned the first set of arms but were not trained to approach the second set. Thereafter, animals in each interference condition were assigned to groups (hippocampal, cortical control, unoperated control), the operations were carried out, and then all animals were tested for retention of the set of arms learned first. Contrary to predictions of the cognitive map theory, O' Keefe & Nadel, 1978), RI was found in control animals. The severe memory deficit found in hippocampals was not influenced by the interference variable. In addition to impaired performance early in relearning, rats with hippocampal lesions continued to make many errors throughout the 10 wk of testing, including choices to unbaited arms and repeated entries into baited arms. However, hippocampals eventually learned not to reenter unbaited arms. These data indicate a deficit in the selection and utilization of sets of responses and are interpreted as implicating the hippocampus in retrieval processes.

Performance of hippocampectomized rats in a reference/working-memory task: Effects of preoperative versus postoperative training

“…On the other hand, Jarrard (1983;Jarrard & Elmes, 1982) reported results that do not agree with the present findings. Jarrard used a task similar to that used here-a radial-maze task with explicit working-memory and reference-memory components-and conducted in a similar experimental environment.…”

“…A precise comparison of the extent of the lesions in the two studies is not possible. However, the discrepant findings may be attributable to differences in the extent of the hippocampal lesions, to differences in the amount of neocortical tissue damage (which is greater in the Jarrard, 1983, andJarrard &Elmes, 1982, experiments than in the present experiment), or to other differential effects of the two techniques.…”

“…However, hippocampectomized rats are capable of inhibiting a punished approach response (e.g., Cogan & Reeves, 1979; in press). Thus, the deficit reported by Jarrard (1983;Jarrard & Elmes, 1982) may be at tributable to a performance deficit (failure to inhibit the nonrewarded response) rather than to a retention deficit. However, further research is necessary to test this hypothesis.…”

Primate models of interference control

“…Subsequent studies demonstrated that not only monkeys [11 ,12] but also pigeons [13,14] and rats [15][16][17][18][19] can also perform dualtasks in various conditions and also exhibit dual-task interference effects analogous to those in humans (Table 1). Recently, Smith et al [12] applied the dual-task method to examine whether or not metacognitive process can be dissociated from perceptual-level process using monkeys.…”

“…Combination of tasks Behavioral studies Moise [9] Monkey DMS a + simple reaction time task Washburn and Astur [10] Monkey DMS + overt OT b or numerical judgment task Basile and Hampton [11 ] Monkey DMS + motor, image perception, or image classification task Smith et al [12] Monkey DMS or DMP c + perceptual confidence judgment Kendrick and Rilling [13] Pigeon DMS + VI d , EXT e , or DRO f schedule Calder and White [14] Pigeon DMS + VI schedule Maki et al [15] Rat 8-arm WS g radial maze + 4-arm WS h radial maze Beatty and Shavalia [16] Rat 8-arm WS radial maze + 8-arm WS or WS radial maze Roberts [17] Rat 8-arm WS radial maze + 8-arm WS radial maze Cook and Brown [18] Rat 12-arm WS radial maze + 12-arm WS radial maze Jarrard and Elmes [19] Rat 12-arm WS radial maze + 4-arm WS radial maze Harper et al [45] Rat SPR i in 12-arm maze + food consumption Neurophysiological studies…”