Delayed alternation task

Fig. 14. Effects of diazepam and scopolamine on the 3 parameters measured during the acquisition of a delayed alternation task in the rat (mean performance over 10 sessions). Note that both diazepam and scopolamine significantly decrease the number of correct responses (impairment of learning/memory). Diazepam has no effect on simple reaction times whereas scopolamine significantly increases it (impairment of attention). Diazepam significantly decreases choice reaction times whereas choice reaction times are clearly increased by scopolamine. The increased choice reaction times with scopolamine probably reflect an impairment of information processing speed, whereas the decrease observed with diazepam probably reflects the disinhibitory effects of diazepam.

Roux S, Hubert I, Lenegre A et al. (1994) Effects of piracetam on indices of cognitive function in a delayed alternation task in young and aged rats. Pharmacol Biochem Behav 49 683-688... 

Dreher J-C, Guignon E, Burnod Y (2002) A model of prefrontal cortex dopaminergic modulatin during the delayed alternation task. J Cogn Neurosci. 

Critical to the interpretation of any memory-related deficits with the delayed alternation task is the inclusion of a zero-second or no-delay condition. The no-delay condition requires no memory, as there is no delay. Therefore, if a treatment is impairing accuracy under the no-delay condition as well as at the various delay intervals, it is likely that the effects are due to changes in behavioral processes other than remembering. The pattern of change consistent with a selective memory impairment of a toxicant, then, is one composed of no change in accuracy at the zero-second delay but a more pronounced decrease in... 

Gilbert, S.G., T.M. Burbacher, and D.C. Rice. 1993. Effects of in utero methylmercury exposure on a spatial delayed alternation task in monkeys. Toxicol. Appl. Pharmacol. 123(l) 130-6. Gilbert, S.G., D.C. Rice, and T.M. Burbacher. 1996. Fixed intervaFfixed ratio performance in adult monkeys exposed in utero to methylmercury. Neurotoxicol. Teratol. 18(5) 539-46. 

Rice, D.C., Gilbert, S.G., 1990a. Sensitive periods for lead-induced behavior impairment on a spatial delayed alternation task in monkeys. Toxicol. Appl. Pharmacol. 103, 364—373. 

Kodama T, Hikosaka K, Watanabe M. 2002. Differential changes in glutamate concentration in the primate prefrontal cortex during spatial delayed alternation and sensory-guided tasks. Exp Brain Res 145(2) 133-141. 

Pharmacological manipulation of DA, within mesostriatal, as well as mesofrontal domains, has profound effects on performance in spatial working memory tasks in both rodents and monkeys. Early work (reviewed by LeMoal and Simon, 1991) demonstrated that 6-OHDA-induced lesions of the meso-accumbens or meso-striatal, as well as the meso-cortical DA projections led to impaired delayed alternation performance in rats. However, there is a question of whether the capacity to hold on-line the location of the previous goal or choice response has been impaired or whether other behavioral capacities, such as the inhibition that is normally required for the spontaneous alternation of choices is disrupted, leading to perseverative responding. 

Other methods for measurement of memory function rely on explicit discrimination tasks. The matching to sample task described earlier is one example. In this paradigm, a sample stimulus is presented briefly to the subject. The subject must then pick the sample stimulus when subsequently presented with multiple stimulus options (i.e., the subject must match the sample). When delay intervals are imposed between the presentation of the sample stimulus and the subsequent presentation of multiple stimuli, the task becomes a memory task. In this case, the subject must remember the sample stimulus in order to perform correctly. As in the delayed alternation procedure. 

The spatial memory of the lower dose groups (50 and 100 / g/kg per day) was tested by a different procedure, delayed alternation. In this task the... 

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