“Ectopic” theta oscillations and interictal activity during slow-wave state in the R6/1 mouse model of Huntington's disease

► We examined spontaneous cortical activity in R6/1, a model of Huntington's disease. ► The segregation between active and slow-wave states is altered in R6/1 mice. ► Slow wave sleep was invaded by “ectopic” theta episodes and interictal spikes in R6/1. ► Ectopic theta was reversed by the cholinergic antagonist atropine. ► Altered brain states and cholinergic systems might relate to cognitive decline in HD.