Research Areas

Neuronal circuits in the brain are not rigidly fixed, but can be altered by neuronal activities. This use-dependent plasticity of circuits may be a neuronal basis of higher brain functions such as learning and memory. In this research team, we attempt to elucidate mechanisms underlying such experience-dependent plasticity of neuronal circuits in the cerebral cortex. The developing visual cortex is one of the cortical regions, in which such activity-dependent plasticity of neuronal circuits has extensively been studied since the following Hubel and Wiesel's original findings: Monocular visual deprivation in kittens induces functional changes in binocular visual responses of neurons and morphological changes in ocular dominance columns in the visual cortex. In this context the questions that we are addressing in this research team are as follows.

1. What is a functional role of each of GABAergic inhibitory neurons and glutamatergic excitatory neurons in the experience-dependent plasticity of neuronal circuits in the developing visual cortex? For this objective, we take advantage of various transgenic mice in which GABAergic neurons are marked with fluorescence protein and combine electrophysiology with in vivo two-photon functional calcium imaging of neuronal activities.
2. In the previous studies we found that brain-derived neurotrophic factor (BDNF) play a role in the induction of long-term potentiation (LTP) and endocannabinoids (eCBs) are involved in the induction of long-term depression (LTD) in the developing visual cortex. So, questions are: what mechanisms are involved in the BDNF-dependent LTP and eCB-dependent LTD in visual cortex ?

Research Subject

1. Elucidation of mechanisms underlying long-term potentiation/depression in developing visual cortex
2. Analysis of input-dependent changes in visual cortical neurons by long-lasting functional imaging
3. Functional roles of neurotrophic factors and endocannabinoids in visual cortical plasticity
4. Difference in response selectivity between inhibitory and excitaotry neurons in visual cortex
5. Difference in plasticity between inhibitory and excitatory neurons in developing visual cortex

Related links

1. RIKEN Brain Science Institute Website_Laboratories Page
2. Individual Website Laboratory Page

Press release

April 29, 2010

Marijuana-like substance in the brain identified as important for brain growth

January 27, 2010

Changes in neurons identified even after 'critical period' of brain development

February 19, 2008

Regulating the chemistry of learning
A new study sheds light on how synaptic nerve signals are regulated in the developing brain.

February 21, 2007

Dr. Tadaharu Tsumoto of RIKEN BSI and JST (Japan Science Technology Agency) has developed a new in vivo functional technique which enables simultaneous observation of both inhibitory and excitatory neurons in cerebral cortex of transgenic mice, thereby, revealing a large difference in response to visual cortex stimulation between these neurons.

RIKEN RESEARCH

July 16, 2010

Critical viewing
The maturation of inhibitory synapses in the visual cortex is modulated by visual experience

March 26, 2010

Eyes wide shut
Different cell types in the visual cortex respond differently to changes in visual experience