Nucleus incertus

The nucleus incertus is a region of the rodent pontine brainstem just ventral to the 4th ventricle.

The nucleus incertus has a bilateral structure which sits near the brainstem, and is often also called 'nucleus O'. It consists of mostly ascending GABAergic projection neurons and glutamatergic neurons which innervate a broad range of forebrain regions involved in behavioural activation and the response to stress.

This tegmental nucleus is part of the theta network. The nucleus incertus is a relay from the reticularis pontis oralis nucleus to the septo-hippocampal system. The stimulation of the nucleus incertus activates the hippocampal theta rhythm and either its lesion or inhibition suppress the theta oscillation induced by brainstem stimulation. The nucleus incertus itself presents theta oscillations coupled to the hippocampal theta rhythm.