Jun. Prof. Dr. Motoharu Yoshida, Neurophysiology, Faculty of Psychology
When we think, remember or recall, thousands of neurons are active in the brain. This activity changes rapidly with time, hence the activity is dynamic. Question we ask is how this activity of neurons are coordinated to enable us think, remember, recall, etc.
In our lab, we utilize two different methods to achieve this goal. One is in-vitro electrophysiology where we observe neural activity from individual live neurons. The other is computational modeling where we test how neural activity can contribute to brain function using computer simulation. By combining these two methods, we try to understand how neural activity contribute to brain functions.
We currently focus on functions of the medial temporal lobe which is crucial for learning and memory. After years of study, it still remains unclear how individual neuronal activity is coordinated to support learning and memory in this region. We study electropysiological properties of neurons in the medial temporal lobe that support memory encoding, memory consolidation and spatial navigation. Our current focus is on properties such as persistent firing and subthreshold membrane potential oscillations in the entorhinal cortex and other area in the medial temporal lobe.
Investigation of the roles of persistent firing on memory formation
Neurons in the entorhinal cortex have the ability to persistently fire following a short triggering stimulus. We investigate if this activity helps us to form new memories.
Contribution of persistent firing on brain rhythms
Neurons in the entorhinal cortex can elicit persistent firing as a single cell property. In this research, we investigate what will be the resulting activity at the level of neural network.
The role of persistent firing in the head-direction system
Head-direction system in the postsubiculum tracks the direction of our head. Persistent firing could be the key component of this tracking system. This study focuses on the mechanism of how persistent firing contributes to the head-direction system.
The role of subthreshold membrane potential oscillations in the medial temporal lobe
Neurons in the medial temporal lobe show oscillation at theta frequency (3-10 Hz) when the membrane potential is depolarized. This rhythm could contribute to spatial navigation function of the medial temporal lobe. This study will focus on the precise mechanism of how subthreshold oscillations contribute to spatial navigation.