The dendrite branches of spiny neurons are littered with spines, or receptor sites, for neurotransmitters, including dopamine. Spiny neurons play a crucial role in initiating and regulating movements of the body, limbs, and eyes by receiving signals from neurons in other parts of the brain that produce dopamine. The Brain Mechanism for Behaviour Unit is studying these cells in order to understand their role in Parkinson’s disease. Gordon Arbuthnott, head of the Unit, had previously found that half of these spines are lost from the dendrites when dopamine is removed, as is the case in Parkinson’s.