Triple dissociation of anterior cingulate, posterior cingulate, and medial frontal cortices on visual discrimination tasks using a touchscreen testing procedure for the rat.

Abstract

Four experiments examined effects of quinolinic acid-induced lesions of the anterior cingulate, posterior cingulate, and medial frontal cortices on tests of visual discrimination learning, using a new "touchscreen" testing method for rats. Anterior cingulate cortex lesions impaired acquisition of an 8-pair concurrent discrimination task, whereas posterior cingulate cortex lesions facilitated learning but selectively impaired the late stages of acquisition of a visuospatial conditional discrimination. Medial frontal cortex lesions selectively impaired reversal learning when stimuli were difficult to discriminate; lesions of anterior and posterior cingulate cortex had no effect. These results suggest roles for the anterior cingulate, posterior cingulate, and medial frontal cortex in stimulus-reward learning, stimulus-response learning or response generation, and attention during learning, respectively.

Transfer Effects and Conditional Learning in Rats With Selective Lesions of Medial Septal/Diagonal Band Cholinergic Neurons.

“…An additional comparison of sessions to criterion permitted comparison of the amount of time required for each rat to master each discrimination problem. We also considered whether more detailed analysis of intermediate criterion levels (e.g., sessions to move from chance performance to statistically above chance) might reveal effects on different phases of learning (e.g., Bussey et al, 1997). Because not all of the rats in Experiments 1C and 2 reached criterion on the central-cue visual-spatial discrimination, we were only able to analyze the sessions required to move from chance performance to above chance (61% correct).…”

“…In this study, we sought to explore further the role of cholinergic MS/VDB neurons in visual-spatial conditional tasks, using computer-controlled automated tasks analogous to those used previously in nonhuman primates (Ridley et al, 1999) or in rats (Bussey et al, 1997(Bussey et al, , 2000. We found that lesions of MS/VDB cholinergic neurons were without effect on simple visual discriminations or on the double-cue visual-spatial conditional problem in which the animal responds to either the left or right object of an identical pair, contingent on which pair of objects was displayed.…”

“…The test apparatus was constructed according to the specifications of Bussey and colleagues (Bussey et al, 1994(Bussey et al, , 1997. A clear Plexiglas box (0.50 m ϫ 0.25 m ϫ 0.50 m) with a metal floor was fitted with a touch-sensitive computer screen on one end (Carroll Touch, Round Rock, TX).…”

“…As a follow-up, we tested rats' performance in a second centralcue visual-spatial conditional problem, in which a centrally located visual stimulus (X or Y) directs the rat to make a response to the left or right Bussey et al, 1997;. Although this latter task also requires the use of visual information to emit a spatially directed response, lesions of the fornix or MS/VDB in rats do not impair performance on this task (Bussey, Duck, Muir, & Aggleton, 2000;Marston, Everitt, & Robbins, 1993).…”

“…We used the somewhat impoverished environment produced by the touchscreen apparatus (Bussey, Muir, Everitt, & Robbins, 1997;Bussey, Muir, & Robbins, 1994) to present two-dimensional visual discrimination problems to rats. Rats received injections of the selective cholinergic immunotoxin 192 IgG-saporin into the MS/ VDB (Baxter, Bucci, Gorman, Wiley, & Gallagher, 1995) or a control surgery and then began training on the discrimination learning tasks.…”