Faculty Detail / 研究室詳細

Shigeyoshi Fujisawa, Ph.D.

- Our goal is to elucidate the neuronal and network mechanisms underlying reward-related cognitive functions.

Laboratory for Systems Neurophysiology

Team Leader

Large-scale recordings of neuronal activities, Brain oscillation

Shigeyoshi  Fujisawa

Research Area

Our main research goal is to elucidate the neuronal and network mechanisms underlying reward-related cognitive functions, particularly the contribution of the dopaminergic circuits of the basal ganglia, the prefrontal cortex and the hippocampus. Studying the physiological mechanisms of cognitive functions requires understandings not only the responses of single neurons to external stimuli but also circuit computations at the level of networks of neurons during cognitive processing. To understand the ‘syntax’ underlying neuronal communications, methods for monitoring and quantifying cooperative neuronal activities during cognition are required. To this end, we have been performing large-scale high-density recordings of local circuits with multi-channel silicon probes, enabling the observation of simultaneous neuronal firing activities in up to 100 neurons, as well as local field potentials in behaving animals. In addition, we are developing a new technique that combines large-scale recording and targeted simultaneous optogenetic stimulations of specific cells, such as dopaminergic neurons, to clarify the role of the different types of neurons in network processing, in freely behaving mice. Taking advantage of these methods, we try to decipher circuit computations within local and between the inter-regional networks during reward-related cognitions such as decision making and working memory.

Selected Publications View All

  1. 1

    Patel J, Fujisawa S, Berényi A, Royer S, and Buzsáki G: "Traveling theta waves along the entire septotemporal axis of the hippocampus.", Neuron, 75(3), 410-7 (2012)

  2. 2

    Fujisawa S, and Buzsáki G: "A 4 Hz oscillation adaptively synchronizes prefrontal, VTA, and hippocampal activities.", Neuron, 72(1), 153-65 (2011)

  3. 3

    Sirota A, Montgomery S, Fujisawa S, Isomura Y, Zugaro M, and Buzsáki G: "Entrainment of neocortical neurons and gamma oscillations by the hippocampal theta rhythm.", Neuron, 60(4), 683-97 (2008)

  4. 4

    Fujisawa S, Amarasingham A, Harrison MT, and Buzsáki G: "Behavior-dependent short-term assembly dynamics in the medial prefrontal cortex.", Nat Neurosci, 11(7), 823-33 (2008)

  5. 5

    Fujisawa S, Matsuki N, and Ikegaya Y: "Single neurons can induce phase transitions of cortical recurrent networks with multiple internal States.", Cereb Cortex, 16(5), 639-54 (2006)

  6. 6

    Fujisawa S, Matsuki N, and Ikegaya Y: "Chronometric readout from a memory trace: gamma-frequency field stimulation recruits timed recurrent activity in the rat CA3 network.", J Physiol, 561(Pt 1), 123-31 (2004)

  7. 7

    Fujisawa S, Yamada MK, Nishiyama N, Matsuki N, and Ikegaya Y: "BDNF boosts spike fidelity in chaotic neural oscillations.", Biophys J, 86(3), 1820-8 (2004)