In many mammals, seasonal variations in thyroid hormone levels coincide with changes in both whole-body metabolism and exploratory behaviour, such as foraging. Hochbaum et al. now show that thyroid hormone remodels cortical circuits to modulate exploration in male mice.

The authors discovered that administration of the active form of thyroid hormone, T3, promotes exploration in several behavioural tests in adult male mice, consistent with a role for the hormone in driving this adaptive behaviour.