Posterodorsal septal lesions impair performance on both shift and stay working memory tasks.

Abstract

Two groups of rats were trained preoperatively on either a shift or a stay problem in a T-maze. Training trials consisted of two runs, an "information run" in which a subject was forced to go down one of the two arms of the T-maze, followed immediately by a "choice run" in which the subject could choose either arm. In the shift condition, rats were rewarded with wet mash only for choosing the arm opposite the one they entered on the information run. In the stay condition, rats were rewarded for entering the arm that was entered on the information run. In both conditions, rats ultimately learned to perform with median accuracy of 100%, but the shift group reached this level of performance after fewer trials than the stay group. In a subsequent phase, the delay between information runs and choice runs was increased from 0 to 30, 60, 90, 210 and then decreased back to 0 s. Choice accuracy in both groups declined as the delay increased and returned to 100% at the 0-s delay. Half of the subjects in each condition then received either lesions of the posterodorsal septum-aimed at disconnecting the septum and hippocampus-or control surgery. Postoperative retention deficits resulted from posterodorsal septal lesions in both shift and stay conditions. There was some recovery of performance but no indication of "savings" during postoperative training. These results indicate that deficits in maze performance by rats with septo-hippocampal damage are not restricted to tasks that require alternation of spatial locations. This finding falsifies the notion that maze deficits reflect a spontaneous alternation deficit or changed "spatial strategy," but it supports the hypothesis of a working memory deficit in these animals.

GABA Affects Novel Object Recognition Memory and Working Memory in Rats

“…However, the accuracy rate was not correlated with an increase in the concentration of GABA. Stanton et al (26) showed that posterodorsal septal lesions impair behavioral functions, resulting in a decrease in the accuracy rate in both the delayed matching to sample (DMTS) and delayed non-matching to sample (DNMTS) tests. Furthermore, declines in the accuracy rate in the DNMTS task in T-maze test have been reported in relation to lesions in the inside septum (27), outside septum (28), entorhinal cortex (29), and the CA3 region of the hippocampus (30,31).…”

A new method for studying working memory by using the three-panel runway apparatus in rats.

“…Delayed matching to sample procedure (DMTS) is frequently used for studying short-term memory or working memory (1,2). In the rat experiment, there are usually two selections (right side or left side), so the chance level is high (50%).…”

Rats acquire win-stay more readily than win-shift in a water escape situation

“…Also, when given a choice, they typically enter a novel, previously unavailable alley rather than an alley in which they have been repeatedly reinforced (Means et al, 1974). Furthermore, in a study comparing acquisition of win-stay and win-shift responses during pairs of trials in aT-maze in which the animal was forced to a randomly selected goal box on the first trial and given a choice on the second trial, it was demonstrated that rats are capable of acquiring either response, but that it takes fewer trials to acquire the win-shift response (Stanton, Thomas, & Brito, 1984). Also, in the radial-arm maze rats spontaneously enter novel (unentered) alleys and more readily learn to enter previously unentered arms (win-shift) than to return to arms that have already been entered (win-stay), even if each arm is baited with food or water before all trials (Gaffan & Davies, 1981;Olton & Schlosberg, 1978).…”