The Effects of AMPA‐induced Lesions of the Medial Septum and Vertical Limb Nucleus of the Diagonal Band of Broca on Spatial Delayed Non‐matching to Sample and Spatial Learning in the Water Maze

Abstract

These experiments investigated in the rat the impact on spatial delayed non-matching to sample and on acquisition of the Morris water maze of (i) AMPA-induced lesions of the medial septal nucleus, which produced a marked reduction of hippocampal choline acetyltransferase activity and acetylcholine levels (measured using in vivo dialysis) together with lesser reductions in cholinergic markers in the cingulate cortex and (ii) similar AMPA-induced lesions of the vertical limb nucleus of the diagonal band of Broca (vDB), which produced more marked reductions in cholinergic markers in the cingulate cortex than in the hippocampus. Medial septal lesions produced a delay-dependent deficit in spatial working memory, while lesions of the vDB resulted in a delay-independent performance deficit. In addition, rats with vDB lesions adopted biased response strategies during the imposition of long delays. Neither lesion significantly affected the acquisition of a spatial reference memory task, the Morris water maze. The results are discussed in terms of cholinergic- and GABAergic-dependent functions of the hippocampal formation and cingulate cortex in spatial short-term and reference memory.

Automatic recording of mediating behavior in delayed matching- and nonmatching-to-position procedures in rats

“…The baseline accuracy of delayed matching and nonmatching behavior in the present study was comparable to the performance of rats in other DMTP and DNMTP studies that involved retractable levers (e.g., Bushnell 1988; Harper et al 2006) or illuminable nose-poke holes (Etherington et al 1987; McAlonan et al 1995). Treatment with amnestic drugs produced dose-dependent decreases in accuracy that were comparable to those seen in previous studies with scopolamine (Bushnell 1990; Chudasama and Muir 1997; Dunnett 1985) or THC (Mallet and Beninger 1998; Hampson and Deadwyler 2000; Heyser et al 1993).…”

Intraseptal injection of the 5-HT1A/5-HT7 agonist 8-OH-DPAT and working memory in rats

“…Such behaviour might reflect a deficit of non-mnemonic processes, possibly of attention or exploration strategies. Concerning attention, different authors suggested that spatial perturbations induced by septal lesions may reflect deficits of attention processes rather than a pure memory deficiency (McAlonan et al 1995;Brandner and Schenk 1998). In addition, 8-OH-DPAT administered systemically was shown to reduce performance in tasks assessing attention processes (Carli and Samanin 2000;Nakamura and Kurasawa 2000).…”

The Serotonin1AReceptor Partial Agonist S15535 [4-(Benzodioxan-5-yl)1-(indan-2-yl)piperazine] Enhances Cholinergic Transmission and Cognitive Function in Rodents: A Combined Neurochemical and Behavioral Analysis

“…"Delayed nonmatching to position" models of short-term, spatial working memory, in which rats choose between spatially separated, retractable levers, are dependent upon the operation of cholinergic mechanisms in the hippocampus and FCX (McAlonan et al, 1995;Herremans et al, 1996). Although it has been questioned whether mnemonic (compared with motor) factors underlie the perturbation of performance in this model provoked by activation of hippocampal 5-HT 1A receptors, stimulation of 5-HT 1A autoreceptors specifically improves cognitive function (Cole et al, 1994;Porsolt et al, 1995;Stanhope et al, 1995;Warburton et al, 1997;Pache et al, 2003).…”