Research

How does the brain transform sensory cues into behavioral decisions?

The olfactory system is connected to the hippocampus and prefrontal cortex without the relay of the thalamus. This anatomical configuration places the olfactory system as an ideal sensory system for investigating in details how sensory information is transformed into behavioral outputs at each brain region. The usage of olfaction is also advantageous for designing behavioral tasks for rodents, since rodents heavily rely on the olfactory system.

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Using this circuit, the Igarashi laboratory investigates:
(i) Internal representations for memory, perception and decision making
(ii) Neuromodulatory controls of internal representations

(iii) How internal representations degenerate in Alzheimer's disease and psychiatric disorders

To solve these problems, we are targeting the high-order olfactory regions, including the olfactory cortices, entorhinal cortex, neuromodulatory systems, and prefrontal cortex.

Our focus has been the lateral entorhinal cortex (LEC), where we found neurons for olfactory memory (Igarashi et al., Nature 2014). These neurons acquire olfactory memory using dopamine (Lee et al., Nature 2021), and work together with neurons in the medial prefrontal cortex for sorting out olfactory memory (Jun et al., Nature 2024).

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We use state-of-the-art systems neuroscience techniques including:

•  Optogenetic-assisted in vivo multi-unit spike and LFP recordings

• Olfactory-cued memory behavior tasks

• High-resolution functional anatomy

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These works have been supported by grants from NIH/NIA, NIH/NIMH, Whitehall Foundation, Alzheimer's Association, Brain Research Foundation, Office of Naval Research, Japan Science and Technology Agency, Donors Cure Foundation, and Brightfocus Foundation.