Susumu Tomita, PhD

My laboratory’s approach to understand brain is to reduce brain to various components and ultimately molecules. The primary functional component of brain is the neural circuit, which are comprised of anatomical neuronal wiring and synaptic transmission. Temporally, neurotransmission by a major excitatory neurotransmitter in brain, glutamate, is very quick and is clearly essential for brain function; however, the modulation of brain function underlying learning, memory, emotion, cognition, etc., happens on a different time scale than that of neurotransmission. Our broad goal is to understand how basic synaptic transmission can be modulated over seconds to hours, thereby supporting complex brain functions.The efficacy of synaptic transmission is determined by glutamate concentration at the synaptic cleft and by the number and channel properties of the glutamate receptors, which can be modulated by neuronal activation (synaptic plasticity).

It is therefore important to determine how many receptors are at synapses and how strongly these receptors are activated upon glutamate releases. We have uncovered a network of modulatory proteins for glutamate receptors to control their number and properties. By understanding the machinery that controls the number and channel properties of glutamate receptors, we hope to reveal the principal rules governing synaptic transmission and synaptic plasticity. Combined with neuronal wiring mapping, this should help us understand a big picture of neural circuits and the momentary changes that occur in neural circuits to control animal behavior.