Communication between neurons (brain cells) occurs at specialized junctions known as synapses. The process involves presynaptic neurons releasing neurotransmitter molecules, which then bind to membrane receptors on the surface of postsynaptic neurons – triggering the postsynaptic neuron to “fire.” The normal function of the brain depends on balancing the number of active receptors at the synaptic junction, so that neurons fire appropriately. Alzheimer’s disease and mental retardation show decreased receptor activity, whereas epilepsy and stroke show an excess of receptor activation. In effect, these conditions are marked by neural transmissions that are either too weak or too strong. Dr. Jun Liu previously practiced as a neurosurgeon in his native China. Now, he is studying how cellular and molecular mechanisms in brain cells support learning and memory. Recent findings indicate that the number of receptors activated on postsynaptic neurons can be rapidly regulated, suggesting a novel and efficient means by which the strength of synaptic transmission can be altered. Liu is investigating how such rapid changes in the number of postsynaptic receptors, and hence synaptic transmission strength, are initiated and carried out. Improved understanding of how receptor activity is regulated will help researchers learn how to correct receptor imbalances, offering new hope for a number of debilitating neurological conditions.