Final answer:
Huntington's disease is characterized by the loss of GABAergic medium-sized spiny neurons and the neurotransmitter gamma-aminobutyric acid (GABA).
Step-by-step explanation:
Huntington's disease is characterized by the loss of GABAergic medium-sized spiny neurons, which release the neurotransmitter gamma-aminobutyric acid (GABA). The loss of these neurons results in a range of physical, psychological, cognitive symptoms. It has been suggested that weak glutamate antagonists may provide a clinically relevant outcome if they can be designed to block extrasynaptic NMDA receptors without preventing normal synaptic NMDA receptor activity.