To respond effectively to sensory stimuli, animals depend on neural circuits that assimilate sensory information and coordinate motor output. The habenula, a set of evolutionary conserved, bilateral nuclei, is a node in the vertebrate brain that connects the forebrain to the ventral midbrain and plays a key role in modulating a variety of behaviours, including arousal, fear, anxiety and reward. The habenula can be divided into anatomically and molecularly distinct nuclei termed the medial and lateral habenula in mammals or the dorsal (dHb) and ventral habenula (vHb) in lower vertebrates. The dorsal habenula is further divisible into two subnuclei - dHbM and dHbL. All three subdomains of the habenula differ substantially in the genes and neurotransmitters they express, the downstream targets they innervate, and the neuromodulators they control. It is therefore unsurprising that several studies have documented a relationship between habenula subdomains and behavior. In zebrafish, there is an olfactory response mainly residing in the right dHbM, contrasting with a light response that is largely localized to the left dHbL. However, knowledge of the precise role each subdomain plays in behavior is missing due to an inability to control neural activity in these regions selectively. Therefore, developing technologies that allow manipulation of habenula subnuclei either individually or in conjunction, is key to advancing our understanding of the neural mechanisms by which circuits orchestrate specific behaviour. Using CRISPRs for transgenesis, we are developing molecular techniques based on the principles of intersectional genetics to allow selective control of a subset of neurons or specific subnuclei of habenula. This poster will describe our progress so far.