CANTAB delayed matching to sample task performance in juvenile baboons

Abstract

This study reports the administration of the Cambridge Neuropsychological Test Automated Battery system's delayed matching to sample (DMTS) task to juvenile baboons. Nine subjects (female=5, male=4) were trained with delay intervals ranging from 0 to 80s. Trial unique stimuli were utilized in combination with matching to sample, in contrast to non-matching to sample, to more accurately assess components of medial temporal lobe (hippocampal formation) mediated working memory. These parameters force subjects to rely on recognition for matching stimuli and overcome their innate tendency to choose novel stimuli (non-matching), thus increasing task difficulty. Testing with delays intervals of 0-2, 4, 8, and 16s revealed decreased percent correct responding as delay intervals increased. An effect of 1 vs. 3 distractor stimuli on accuracy was also noted. Increasing the number of distractors resulted in decreased observing response latencies. The increase in choice response latency seen with increasing delay interval was independent of number of distractor stimuli presented. There were no sex differences in task performance. Our laboratory is focused on understanding the functional consequences of suboptimal conditions during pregnancy and early postnatal life in offspring. The ability of juvenile baboons to perform the DMTS task demonstrates the utility of this non-human primate model in examining pre- and post-natal conditions that impact the development of working memory. Evaluation of causes and consequences of impaired working memory in a variety of human diseases will be assisted by the use of this task in nonhuman primate models of human health and disease.

Figure 1

Figure 1A) Accuracy comparisons between delay intervals under 1 distractor condition. Accuracy following 0 or 1sec delay intervals is higher than after 4, 8 and 16 sec delays (*, p<0.05); accuracy following 2 or 4 sec delays is higher than after 8 and 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1B) Accuracy comparisons between delay intervals under 3 distractor condition. Accuracy following 0 sec delay intervals is higher than after 8 and 16 sec delays (*, p<0.05); accuracy following 1, 2, 4 and 8 sec delays is higher than after 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1C) Accuracy comparisons between 1 (open bar) and 3 (closed bar) distractor conditions. An effect of number of distractors was determined at 0, 1, 2, and 16 sec delays (*, p<0.05). Mean ± SEM.

Figure 1

Figure 1A) Accuracy comparisons between delay intervals under 1 distractor condition. Accuracy following 0 or 1sec delay intervals is higher than after 4, 8 and 16 sec delays (*, p<0.05); accuracy following 2 or 4 sec delays is higher than after 8 and 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1B) Accuracy comparisons between delay intervals under 3 distractor condition. Accuracy following 0 sec delay intervals is higher than after 8 and 16 sec delays (*, p<0.05); accuracy following 1, 2, 4 and 8 sec delays is higher than after 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1C) Accuracy comparisons between 1 (open bar) and 3 (closed bar) distractor conditions. An effect of number of distractors was determined at 0, 1, 2, and 16 sec delays (*, p<0.05). Mean ± SEM.

Figure 1

Figure 1A) Accuracy comparisons between delay intervals under 1 distractor condition. Accuracy following 0 or 1sec delay intervals is higher than after 4, 8 and 16 sec delays (*, p<0.05); accuracy following 2 or 4 sec delays is higher than after 8 and 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1B) Accuracy comparisons between delay intervals under 3 distractor condition. Accuracy following 0 sec delay intervals is higher than after 8 and 16 sec delays (*, p<0.05); accuracy following 1, 2, 4 and 8 sec delays is higher than after 16 sec delays (+, p<0.05). Mean ± SEM. Figure 1C) Accuracy comparisons between 1 (open bar) and 3 (closed bar) distractor conditions. An effect of number of distractors was determined at 0, 1, 2, and 16 sec delays (*, p<0.05). Mean ± SEM.

Figure 2

Figure 2A) Observing response latency for all delay intervals under each distractor condition. Increasing number of distractors reduced observing response latency but did not reach significance p=0.3. Figure 2B) Choice response latencies per delay intervals under 1 distractor condition. Latency following 0 sec delay intervals is shorter than after 1, 2, 4, and 16 sec delays (*, p<0.05). Mean ± SEM. Figure 2C) Choice response latencies per delay intervals under 3 distractor condition. Latency following 0 and 2 sec delay intervals is shorter than after 4 and 16 sec delays (*, p<0.05); latency following 1 sec delays is shorter than after 16 sec delays (+, p<0.05). Mean ± SEM.

Figure 2

Figure 2A) Observing response latency for all delay intervals under each distractor condition. Increasing number of distractors reduced observing response latency but did not reach significance p=0.3. Figure 2B) Choice response latencies per delay intervals under 1 distractor condition. Latency following 0 sec delay intervals is shorter than after 1, 2, 4, and 16 sec delays (*, p<0.05). Mean ± SEM. Figure 2C) Choice response latencies per delay intervals under 3 distractor condition. Latency following 0 and 2 sec delay intervals is shorter than after 4 and 16 sec delays (*, p<0.05); latency following 1 sec delays is shorter than after 16 sec delays (+, p<0.05). Mean ± SEM.

Figure 2

Figure 2A) Observing response latency for all delay intervals under each distractor condition. Increasing number of distractors reduced observing response latency but did not reach significance p=0.3. Figure 2B) Choice response latencies per delay intervals under 1 distractor condition. Latency following 0 sec delay intervals is shorter than after 1, 2, 4, and 16 sec delays (*, p<0.05). Mean ± SEM. Figure 2C) Choice response latencies per delay intervals under 3 distractor condition. Latency following 0 and 2 sec delay intervals is shorter than after 4 and 16 sec delays (*, p<0.05); latency following 1 sec delays is shorter than after 16 sec delays (+, p<0.05). Mean ± SEM.