P319 Interactions between functional microcircuits involving three inhibitory interneuron subtypes for the surround modulation in V1
Nobuhiko Wagatsuma*1, Tomoki Kurikawa2, Sou Nobukawa3,4
1Faculty of Science, Toho University, Funabashi, Chiba, Japan 2Future University Hakodate, Hakodate, Hokkaido, Japan 3Department of Computer Science, Narashino, Chiba Institute of Technology, Chiba, Japan 4Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
*Email: nwagatsuma@is.sci.toho-u.ac.jp
Introduction A functional microcircuit of V1 for interpreting the external world resides in layers 2/3 and consists of excitatory pyramidal (Pyr) neurons and three inhibitory interneuron subtypes: parvalbumin (PV), somatostatin (SOM), and vasoactive intestinal polypeptide (VIP). Recent physiological and computational studies suggest a structured organization of this microcircuit and distinct roles of inhibitory interneuron subtypes in modulating neural activity for visual perception [1,2]. Interactions between these microcircuits across receptive fields are crucial for integrating larger visual regions and forming perception, yet the precise structures and interneuron subtypes mediating these interactions remain unclear.
Methods We developed a computational microcircuit model of the functional unit with biologically plausible visual cortical layers 2/3 that combined excitatory Pyr neurons and three inhibitory interneuron subtypes and explored the role of specific inhibitory interneuron subtype for mediating the interactions between these two microcircuits via the lateral inhibition across receptive fields (Fig.(A)). We assumed that the receptive fields of these units, which share common orientation selectivity, are spatially adjacent in the visual field. In this study, two functional microcircuits interacted each other via the lateral inhibition from excitatory Pyr neurons in one unit to PV or SOM inhibitory interneurons in the other. Results We performed simulations of the model with inputs mimicking small and large visual stimuli used in the physiological experiment [3]. We assumed that the small stimulus was confined to the receptive field of a single unit, whereas the large stimulus extended across the receptive fields of two microcircuits. Model simulations with the large visual stimulus implied that the lateral inhibition from Pyr neurons in one microcircuit to SOM interneurons in the other preferentially induced neuronal firing at beta (13-30 Hz) frequency, in agreement with physiological responses for the surround suppression in V1 [3]. By contrast, the model with the lateral inhibition mediated by PV interneurons distinct modulation patterns from physiological results. Discussion Our model reproduced characteristic neuronal activities in V1 induced by the surround modulation when the lateral inhibition across the receptive fields was mediated by SOM interneurons. Our results of model simulations suggested the specific role of SOM interneurons in the long-range lateral interactions across receptive fields in V1, which might contribute to the generation of surround modulation.
Figure 1. (A) Proposed microcircuit model. These two microcircuits interacted each other via lateral connections from Pyr neurons in one unit to PV or SOM interneurons in the other. (B) Simulation results. Black and blue lines indicated the oscillatory responses of the model with the lateral inhibition mediated by SOM and PV interneurons, respectively. The red line was those with the small stimulus. Acknowledgements This work was partly supported by the Japanese Society for the Promotion of Science (JSPS) (KAKENHI grants 22K12138, 22K12183, 23H03697, and 23K06394) and a grant of the Research Initiative Program of Toho University (TUGRIP). References 1. https://doi.org/10.1093/cercor/bhac355 2. https://doi.org/10.1016/j.celrep.2018.10.029. 3. https://doi.org/10.1038/nn.4562.
