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Basal forebrain lesions in monkeys disrupt attention but not learning and memory
M L Voytko1, D S Olton, R T Richardson
1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196.
Summary
Lesions in the basal forebrain cholinergic system (BFCS) of monkeys primarily impaired attention, not memory. This suggests BFCS neuron degeneration in Alzheimer's disease may cause attention deficits.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Neurobiology
Background:
- Dysfunction of the basal forebrain cholinergic system (BFCS) is linked to cognitive impairments.
- Degeneration of BFCS neurons may contribute to cognitive deficits in Alzheimer's disease (AD).
Purpose of the Study:
- To investigate the effects of BFCS lesions on cognitive functions in primates.
- To determine if BFCS lesions impact mnemonic or attentional abilities in monkeys.
Main Methods:
- Systematic behavioral investigation using ibotenic acid injections in key BFCS nuclei (medial septum, nucleus of the diagonal band of Broca, nucleus basalis of Meynert) in cynomolgus monkeys.
- Evaluation across a range of cognitive tasks assessing mnemonic and attentional capacities.
- Assessment of scopolamine sensitivity in a delayed nonmatching-to-sample task post-lesion.
Main Results:
- BFCS lesions did not impair performance on various memory-related tasks, including delayed nonmatching-to-sample and delayed response.
- Lesions significantly disrupted attentional focusing abilities in the monkeys.
- BFCS-lesioned monkeys showed increased sensitivity to the cholinergic antagonist scopolamine.
Conclusions:
- The primate basal forebrain appears more critical for attentional processes than mnemonic functions.
- Degeneration of BFCS neurons in Alzheimer's disease may underlie the attention deficits observed in patients.