The Regulatory Role of the Human Mediodorsal Thalamus.

The function of the human mediodorsal thalamic nucleus (MD) has so far eluded a clear definition in terms of specific cognitive processes and tasks. Although it was at first proposed to play a role in long-term memory, a set of recent studies in animals and humans has revealed a more complex, and broader, role in several cognitive functions. The MD seems to play a multifaceted role in higher cognitive functions together with the prefrontal cortex and other cortical and subcortical brain areas. Specifically, we propose that the MD is involved in the regulation of cortical networks especially when the maintenance and temporal extension of persistent activity patterns in the frontal lobe areas are required. Highlights The mediodorsal thalamic nucleus is involved in the cognitive deficits observed in several neurological and psychiatric disorders. The long-standing belief in a role of the mediodorsal thalamic nucleus mainly in long-term memory is now being reconsidered. Recent studies emphasize its function in many cognitive tasks related to the prefrontal cortex. The mediodorsal thalamic nucleus is required for the rapid and accurate performance of cognitive tasks and temporally extends the efficiency of cortical networks involving the prefrontal cortex. We propose that the common ground of multiple lines of evidence from human studies points to a role of the mediodorsal thalamic nucleus in regulating prefrontal activity patterns. These hypotheses can be tested by developing specific neuropsychological tasks, parceling the thalamus with high-resolution MRI, and using intracranial recordings in humans. [ABSTRACT FROM AUTHOR]