Showing papers by "Trevor W. Robbins published in 1987"
TL;DR: Although DA and NA participate in qualitatively different behavioural processes, the effects of DNAB lesions on attentional processes depend on the level of DA activity within the nucleus accumbens, which is antagonised by systemic administration of the specific dopaminergic (DA) antagonist alpha-flupenthixol.
Abstract: A series of experiments examined the effects of lesions of the dorsal noradrenergic bundle (DNAB), induced by 6-hydroxydopamine (6-OHDA), on the behavioural response to systemic and intra-accumbens amphetamine, using a rat analogue of Leonard's 5-choice serial reaction time task for humans. Although the 6-OHDA DNAB lesion produced a profound depletion of cortical noradrenaline (NA) (to around 5% of control levels) it did not impair any aspect of performance on this task. Both systemic and intra-accumbens amphetamine increased behavioural measures of impulsivity of responding, but neither impaired discriminative accuracy in the sham-operated control rats. However, the DNAB lesioned rats did show a discriminative impairment following both low doses of systemic amphetamine, and intra-accumbens amphetamine. The latter effect was antagonised by systemic administration of the specific dopaminergic (DA) antagonist alpha-flupenthixol. The DNAB lesion did not alter the effect of amphetamine on any other behavioural measure, including speed and impulsivity of responding. These results suggest that although DA and NA participate in qualitatively different behavioural processes, the effects of DNAB lesions on attentional processes depend on the level of DA activity within the nucleus accumbens.
253 citations
TL;DR: The results do not indicate a simple relationship between cholinergic neuronal loss and the retention of response rules essential for performance of the task ("reference memory"), and contingency analysis of the behavioural, neurochemical and neuroanatomical data indicated that those animals with the largest decreases in choline acetyltransferase activity, or the largest areas of neuronal loss in the ventral and dorsal globus pallidus, were most impaired in the retention.
184 citations
TL;DR: In six experiments, the effects of lesions to either the dorsal or ventral noradrenergic bundle on the acquisition and extinction of the conditioned emotional response (CER) as measured in a conditioned suppression paradigm were studied, with reference to Gray's "anxiety" and Mason's "selective attention" theories of locus coeruleus function.
Abstract: In six experiments we studied the effects of lesions to either the dorsal or ventral noradrenergic bundle on the acquisition and extinction of the conditioned emotional response (CER) as measured in a conditioned suppression paradigm. Infusions of the neurotoxin 6-hydroxydopamine (6-OHDA) into the trajectory of the dorsal noradrenergic ascending bundle (DNAB) impaired the acquisition of on-the-baseline and off-the-baseline conditioned suppression. The acquisition impairment for on-the-baseline conditioning was also shown to still be present when training did not commence until 8 weeks following central noradrenergic depletion. However, in rats previously trained on the CER, DNAB lesions did not affect performance. There was also a small resistance to extinction following on-, but not off-the-baseline conditioning. The acquisition impairment was shown not to be because of an altered sensitivity to the footshock. In contrast, infusions of 6-OHDA into the ventral noradrenergic ascending bundle (VNAB) had no effect upon the acquisition of the CER in an on-the-baseline procedure, but retarded its extinction to a much greater extent. The results here are discussed in terms of other acquisition deficits shown by rats with DNAB lesions, and with reference to Gray's "anxiety" and Mason's "selective attention" theories of locus coeruleus function.
58 citations
TL;DR: The effects of lesions of the major catecholamine projections and terminal fields induced by 6-hydroxydopamine (6-OHDA), and of lesions of the cholinergic cells in the ventral pallidum/substantia innominata induced by ibotenic acid were compared within a single behavioural paradigm, the acquisition and performance of an appetitive conditional discrimination.
46 citations
TL;DR: The results emphasize the potential for long-term sequelae of the DNB lesion, and the existence of a critical NNC threshold (∼10–30% of control NNC values) which modulates postsynaptic α2 and β1-adrenoceptor density.
17 citations
TL;DR: Pyrithioxin had no effect on locomotor activity or swim speed, but enhanced one trial passive avoidance retention in both young and old animals, and enhanced sensitivity to foot shock and retention of the water maze in old animals.
Abstract: Behavioural effects were assessed in both young and old rats of the pyridine derivative pyrithioxin, which has been reported to elevate acetylcholine levels in several brain regions in old rats. Pyrithioxin was administered in rats' food according to two separate dosing regimens (200 and 600 mg kg -1) over a 6 week period. Spontaneous locomotor activity was measured weekly in photocell cages. Two measures of memory were used: one trial step-down passive avoidance, and spatial learning and retention in the Morris water maze. Pyrithioxin had no effect on locomotor activity or swim speed, but enhanced one trial passive avoidance retention in both young and old animals. The drug also enhanced sensitivity to foot shock and retention of the water maze in old animals.
6 citations