The role of the mediodorsal thalamic nucleus in human olfaction

Abstract

Olfaction has a unique dual-route pathway to the neocortex - one being via the mediodorsal nucleus of the thalamus (MDNT). In this study we explored the role of the MDNT pathway, by comparing six patients with MDNT lesions, with 14 controls, on tests of general olfactory ability (i.e., odor acuity, discrimination, naming, recognition memory and hedonic judgement), visual control and neuropsychological tests, and tests of olfactory attention. The MDNT patients performed normally on most general olfactory tests but showed varying impairments on tests of olfactory attention. These findings suggest that the MDNT pathway is involved, either specifically or generically, in mediating human olfactory attention.