Oral
Vision-Ⅰ
一般口演
視覚-Ⅰ |
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| 7月25日（木）9:00～9:15 第7会場（朱鷺メッセ 2F 201B）
1O-07m1-1
Light dark cycle modulates gut microbiota through intrinsically photosensitive retinal ganglion cells
ShihKuo Chen（Chen ShihKuo）
National Taiwan University
It has been shown that gut microbes can influence the development of the brain and even trigger the degeneration of the neurons in the brain through the gut-brain axis. Interestingly, recent studies showed that some gut microbes display daily oscillation of their relative abundance which is disturbed when animals were housed under chronic jetlag condition. However, whether and how does the sensory system, which detects the light-dark cycle, modulate gut microbiota remain unclear. It is possible that aberrant light-dark cycle could directly influence the gut microbiota or indirectly modulate the gut microbiota through the disturbed circadian clock. To test whether light can modulate the gut microbiota, we housed mice under light at night (LAN) for 2 weeks and performed 16s rRNA sequencing analysis from fecal samples. The 12 hours bright light exposure and 12 hours dim light exposure keeps the animal entrained to 24 hours light-dark cycle and preserve the daily oscillation of master clock in the suprachiasmatic nucleus. Compared with control mice which housed in normal light-dark cycle, mice housed under LAN have distinct gut microbe composition. Furthermore, the daily oscillation of gut microbes was significantly dampened compared to control mice. Furthermore, genetically elimination of intrinsically photosensitive retinal ganglion cell (ipRGC), the atypical photoreceptor for non-image forming functions, strongly dampened the daily oscillation of gut microbes and LAN induced dysbiosis. Together, our results suggest that light could modulate the composition of gut microbiota through ipRGC. Furthermore, the light-dark cycle information transmitted by ipRGC is one of the factors that drive the daily oscillation of gut microbes. | | 7月25日（木）9:15～9:30 第7会場（朱鷺メッセ 2F 201B）
1O-07m1-2
V1 layer 6 corticothalamic feedback encodes behavioral state by complementary activity of distinct neuronal populations
Sigita Augustinaite（Augustinaite Sigita），Bernd Kuhn（Kuhn Bernd）
OIST
Layer 6 (L6), the deepest lamina of cerebral cortex, is one of the key structures regulating behavior state related information processing within cortex and various subcortical areas. However, very little is known about the functional significance of different L6 circuits in vivo. Here, we focus on primary visual cortex L6 feedback projections to visual thalamus (dorsal lateral geniculate nucleus, dLGN) which regulate visual signal transmission from retina to cortex. After injecting fluorescent microspheres into dLGN and AAV.CAG.flex.GCaMP6f into cortex, calcium imaging of retrogradely marked L6 corticothalamic (CT) neurons was performed in vivo with 2P microscopy in a head-fixed Ntsr1-cre mouse. The neuronal activity from the same neurons was recorded for several hours and / or repeatedly recorded during different days while presenting full-screen drifting gratings and monitor mouse activity state with electrocorticogram, pupil size and locomotion speed recordings. This allowed us to study the corticothalamic feedback during different behavior states, ranging from full alertness to sleep. We found, that the average strength of feedback to lateral geniculate nucleus depends on state: neuronal activity increases during more active / alert behavior and decreases with drowsiness. However, feedback is not homogeneous, but composed of complementary signals generated by two different neuronal populations: visual stimulus (i) activated or (ii) suppressed CT neurons. Moreover, even within these groups, distinct subpopulations were found, where neuronal responses differed with respect to preferred level of arousal or locomotion. In this way, L6 corticothalamic neurons continuously report the behavioral state, but during any particular condition, i.e. combination of external sensory input and internal network state, the feedback is generated by distinct sub-populations of neurons. | | 7月25日（木）9:30～9:45 第7会場（朱鷺メッセ 2F 201B）
1O-07m1-3
低次視覚経路と高次視覚経路の独立的な発達
Tomonari Murakami（村上 知成），Teppei Matsui（松井 鉄平），Kenichi Ohki（大木 研一）
東京大学医学部統合生理学
The visual cortical network consists of many areas connected in a highly structured manner. Although the network structure in mature visual cortex has been well studied, it remains unclear how the functional network among visual areas are organized through development. Spontaneous activities play a crucial role in the development of lower-order visual network, from retina to primary visual area (V1). Here, we tracked development of the entire mouse visual cortex simultaneously at multiple developmental stages before the eye opening using wide-field calcium imaging and neuro-tracing. The correlation analysis of spontaneous activity revealed that V1 and higher visual areas (HVAs) were segregated and had a retinotopic-like structure already at a few days after the birth. At this age, the strong functional correlation were observed among HVAs, whereas correlation between V1 and HVAs was much weaker. Consistent with the functional results, neuro-tracing and electrical stimulation confirmed that effective neural projections from V1 to HVAs was largely lacking at this stage. However, we found that connections among HVAs were very sparse at this age. Interestingly, we found that all HVAs, but not V1, received neural projections from lateral posterior nucleus (LPN) in the thalamus prior to the development of V1-HVA and HVA-HVA connections, suggesting that the retinotopically organized functional correlation among HVAs at early developmental stages was not driven by feedforward connections from the primary visual pathway to HVAs but by common subcortical drives from LPN. These results indicate that the visual network among LPN and HVAs develops independently from the primary visual pathway, and that LPN may play an instructive role for the development of the HVA network. | | 7月25日（木）9:45～10:00 第7会場（朱鷺メッセ 2F 201B）
1O-07m1-4
感覚間の情報統合における臨界仮説とその散逸構造
Miki Hirabayashi（平林 美樹）1,2，Hirotada Ohashi（大橋 弘忠）1
1東大院工シス創
2宇宙航空研究開発機構研開
Our objective is to verify the critical brain hypothesis in order to understand neural mechanisms of higher brain functions such as cognition. The idea that brain is self-organized to work in a critical state is called `criticality hypothesis' [1]. The critical state is observed in the order-disorder phase transition. By taking advantage of features of criticality, it is thought that the brain achieves the optimization of memory and the efficient information processing [2]. One of general features is the increase of the correlation length caused by the critical slowing down of the equilibrium-relaxation speed. As a result, several physical quantities follow a power-law distribution. Although it was reported that the size distribution or the duration time of neuronal avalanches (a cascade of neural firings) follows a power-law, it is still unclear how the critical state provides complex brain functions [2].
We already showed that the visual illusion called flash-lag effect [3] and the audio-visual illusion called double-flash illusion [4] can be controlled by the increase of the correlation length due to the critical slowing down of equilibrium relaxation speed [5]. Here, from the thermodynamic point of view, we present a new analysis on the mechanisms that the dissipative structure [6] of neural firings under non-equilibrium critical condition maintains the steady state and achieves the stable information processing. Our results will contribute to understand cognitive principles that realize stable and efficient information processing and to provide simple methods to implement higher-level functions to artificial intelligence.
[1] J. M. Beggs, Philos. Trans. R. Soc. A-Math. Phys. Eng. Sci., 366, 329-343, 2008.
[2] J. Hesse and T. Gross, Front. Sys., Neurosci., 8, 166, 1-14, 2014.
[3] S. Shimojo, Front. Psychol., 5, 196, 1-19, 2014.
[4] L. Shams et al., Nature, 408, 788, 2000.
[5] M. Hirabayashi and H. Ohashi, ICDL-EpiRob 2018, 278-283, 2018.
[6] I. Prigogine and G. Nicolis, Self-Organization in Non-Equilibrium Systems, Wiley, 1977. | |
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