Biology subjects

Yamazaki, R.

Publications and source records attributed to Yamazaki, R..

5 recordsLinked to original sources

bioRxiv2026

Vestibular signals enhance the temporal precision of predictive movements to musical rhythms

Humans exhibit head movements synchronized with musical rhythms, frequently observed during instrument playing or dancing (e.g., hip hop). We conjectured that vestibular input from head movements could aid motor execution anticipatory of musical rhythms, known as sensorimotor synchronization (SMS). To examine this, we applied subthreshold galvanic vestibular stimulation (GVS) simultaneously with musical beats while healthy adults performed SMS to those beats. We designed a GVS waveform where the current rose steeply before each beat onset, which was expected to trigger intense vestibular afferent firing before the beats (as actual head movements would). Participants flexed their index finger in synchrony with the beats of syncopated auditory rhythms. In GVS trials, the SMS timing variability was significantly lower than in trials without GVS, suggesting that vestibular input stabilizes SMS to musical beats. Additionally, a control experiment using a waveform with a gradually increasing current revealed no significant difference in SMS variability between trials with and without GVS. This study provides causal evidence that the vestibular system is involved in synchronized movement to music. In addition, the results suggest that a specific parameter of the GVS waveform could influence predictive motor execution anticipatory of upcoming auditory events.

neuroscience↗

bioRxiv2026

A Scalable Cross-Modal Workflow for Linking In Vivo Neural Activity to Neuronal Cell Types via Spatial Gene Profiling

A central challenge in systems neuroscience research is to elucidate how distinct neuronal cell types coordinate to produce complex behaviors: an endeavor that requires linking their molecular identity, connectivity and activity patterns in behaving animals. Recent advances in single-cell RNA sequencing and spatial transcriptomics have revealed remarkable molecular diversity among neurons. However, most functional recording techniques, including in vivo two-photon calcium imaging, do not reveal the molecular cell identities of recorded cells. Although manual one-to-one matching between functional imaging and post hoc molecular profiling has been achieved for dozens to a few hundred neurons, these approaches are typically labor-intensive, difficult to scale, and capture only a limited fraction of cell types. Integrating these two modalities at large scale remains challenging, limiting our ability to fully understand the general logic of neural computation. Here we present a cross-modal workflow that integrates in vivo two-photon calcium imaging in behaving mice with Expansion-Assisted Iterative Fluorescence In Situ Hybridization (EASI-FISH), a thick-tissue spatial transcriptomic approach. As a proof of concept, we apply this workflow to the mouse dorsal hippocampus, a brain region with high neuronal density and small cell size where manual cell matching is impractical, making it a stringent test for the accuracy and scalability of this method. Using our approach, we achieved highly accurate alignment between in vivo neural activity and ex vivo molecular cell-type identity across hundreds to thousands of neurons, enabling direct mapping of neural dynamics to molecularly defined neuronal populations. We showed that longitudinal neural recordings followed by molecular mapping reveal distinct neural activity patterns that emerge as animals learn a spatial navigation task. By linking activity patterns to molecularly defined cell types, this method provides a framework for testing whether neural representations are organized through cell-type-specific coding or distributed population activity, offering insight into the computational logic by which neural circuits generate complex behaviors.

neuroscience↗

bioRxiv2025

GABA mediates experience-dependent regulation of myelination in the mouse visual pathway.

Myelination in the visual pathway is critical for transmitting visual information from retina to the brain. Reducing visual experience shortens myelin sheath length and slows the conduction velocity of the optic nerve. However, the mechanism underlying such experience-dependent myelination is unclear. Here, we found that closing both eyes, binocular deprivation (BD), during the juvenile period less affects the optic nerve myelination than monocular deprivation (MD) via GABA signaling. RNA-seq analysis of optic nerves from MD and BD mice revealed that GABAergic signaling is downregulated on the deprived side of MD compared to the intact side and BD. Inhibition of GABAergic signaling during the juvenile period resulted in myelin sheath shortening and excessive oligodendrocyte generation in normal mice, similar to the changes observed in MD mice. Enhancing GABAergic signaling rescued the myelin sheath shortening and excessive oligodendrocyte generation in the optic nerve of MD mice. Furthermore, we identified novel GABAergic neurons located within the optic nerve, whose neurites form belt-like presynaptic structures with the oligodendrocyte lineage cells, suggesting a potential source of the GABAergic inputs into oligodendrocytes. Our results indicate that the myelination of visual pathway is maintained by binocular visual inputs via intra-nerve GABA signaling.

neuroscience↗

bioRxiv2024

The flow state is not accompanied by frontal-midline theta activity: An EEG investigation of more than 700 video gameplay sessions

People sometimes experience a "flow state"--characterized by hyperfocus, time distortion, and loss of self-awareness--during sports or video gameplay. Previous neuropsychological studies using simple laboratory tasks have reported that the flow state is associated with activation in the frontal lobe, reflected in theta (4-7 Hz) band rhythmic neural activity in medial prefrontal regions (frontal-midline theta [FMT] activity). However, the findings of previous studies might be problematic because they did not appropriately capture the neural activity associated with the flow state for the following reasons: 1) they used unfamiliar and unmotivating tasks; 2) they defined the neural basis of the flow state as neural activity occurring during tasks of optimal difficulty, disregarding trial-to-trial variations in subjective experience of the flow state; 3) the duration of the experiment or the number of trials was not sufficient to capture the rare experience of flow; or 4) they ignored individual differences in neural activities related to flow experiences. Thus, we examined the relationship between the flow state and FMT activity, recorded via scalp electroencephalography, in an experimental paradigm that addressed these four issues. First, participants played their favorite competitive video games, which they had been routinely playing. Second, task difficulty was kept as uniform as possible across trials by employing rank matching to directly examine the correlation between subjective flow level and FMT activity across trials. Third, to address the concern regarding the low frequency of the flow experience, more than 100 trials were completed over 10 days by each participant. Lastly, we adopted a within-participant statistical approach to examine individual differences in the nature of the flow experience. The results showed no correlation between FMT activity and the degree of subjective flow in six out of seven participants, contrary to previous reports. Our results challenge the conventional view that frontal lobe activity, as reflected in FMT activity, is instrumental in entering into the flow state.

neuroscience↗

bioRxiv2023

Axonal selectivity of myelination by single oligodendrocytes established during development in mouse cerebellar white matter

Myelin formation by oligodendrocytes regulates conduction velocity and functional integrity of neuronal axons. While individual oligodendrocytes form myelin sheaths around multiple axons and control the functions of neural circuits in the brains, it remains unclear if oligodendrocytes selectively form myelin sheaths around the specific types of axons. In this study, we developed a method for observing a single oligodendrocyte and its myelin sheaths around different types of axons in the mouse cerebellar white matter. This was achieved by combining sparse fluorescent labeling of oligodendrocytes by attenuated rabies virus and subsequent immunostaining for axonal markers along with tissue clearing. We revealed that approximately half of the oligodendrocytes showed a preferential myelination of axons originating from Purkinje cells in the adult mice. The preference for Purkinje cell axons was more pronounced during development, when the process of myelination within cerebellar white matter was initiated; over 90% of oligodendrocytes preferentially myelinated the Purkinje cell axons. The transgenic mice that label early born oligodendrocytes showed that their myelin sheaths were predominantly formed around Purkinje cell axons in the adult cerebellar white matter. These results suggest that a significant proportion of oligodendrocytes preferentially myelinate functionally distinct axons in the cerebellar white matter, and the axonal preference of myelination is established during development.

neuroscience↗