一般口演
聴覚 / 視覚
Audition / Vision
座長：藤岡 正人（北里大学医学部） |
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| 2022年7月3日 9:00～9:15 沖縄コンベンションセンター 会議場A2 第7会場
4O07m1-01
難聴耳の左右差における脳構造・機能の変化について
～MRI研究より～
Changes of brain structure and function in patients with unilateral hearing loss
- a magnetic resonance imaging study-
*山本 桂(1)、倉田 二郎(2)、堤 剛(1)
1. 東京医科歯科大学、2. 東京慈恵会医科大学
*Katsura Yamamoto(1), Jiro Kurata(2), Takeshi Tsutsumi(1)
1. Tokyo Medical and Dental University , 2. Jikei University School of Medicine
Keyword: side of hearing loss, VBM, rest state functional connectivity
Hearing loss is potentially associated with cerebral functional and structural alterations that might lead to cognitive deteriorations. To reveal such alterations, we performed magnetic resonance imaging (MRI) of the brain in patients with severe hearing loss at either side of the ear, and examined between-group differences in cortical volume and functional connectivity. We tested a hypothesis that unilateral hearing loss might eventually affect cognitive function of the brain via similar mechanisms. We enrolled patients with severe right (n = 9) or left (n = 11) hearing loss, with an average hearing-loss duration of 16.2 years. They underwent whole-brain resting-state functional and 3-dimentional high-resolution anatomical MRI in a 3-Tesla MRI scanner following hearing tests of both ears. We examined between-group differences in gray matter volume by voxel-based morphometry (VBM), as well as in functional connectivity from the resting-state MRI data, using Matlab, SPM12, and CONN software packages. We found that gray matter volumes of the left superior temporal gyrus and the left middle temporal gyrus (LMTG) were larger in left hearing-loss patients than right hearing-loss patients. Next, we put region-of-interest at LMTG and analyzed its functional connectivity with the entire brain with age as a covariate. We found that the LMTG showed significantly high functional connectivity with the left superior frontal gyrus, left inferior frontal gyrus (Broca's area), left middle frontal gyrus, left frontal pole, and left lateral prefrontal cortex in left hearing-loss patients. The pattern of connectivity in right hearing-loss patients was slightly different from that of left hearing-loss patients. Duration of hearing loss was negatively correlated with connectivity between the LMTG and the left Broca's area, and positively correlated with connectivity between the LMTG and left middle frontal gyrus in left hearing-loss patients. In a between-group comparison, connectivity between the LMTG and right cerebellum in left-hearing loss patients was stronger than that of right-hearing loss patients. The present results might suggest that the right-ear audition is more influential than the left-ear one in inducing cerebral structural changes. Furthermore, the increase in age-related connectivity with the frontal pole, responsible for working memory and language, may also contribute to the structural changes in LMTG. The middle frontal gyrus may be the specific region for right-ear auditory stimuli. A high connectivity between LMTG and the right cerebellum in left-hearing loss patients might imply an altered auditory pathway to the cerebellum. The amount of auditory input and the difference of input between left/right ear might have affected connectivity strength. The dominant, left, hemisphere, appeared more likely to show plastic changes of the brain. | | 2022年7月3日 9:15～9:30 沖縄コンベンションセンター 会議場A2 第7会場
4O07m1-02
迷走神経刺激による聴覚野の神経活動の変化
Modulation of neural activities in auditory cortex by vagus nerve stimulation
*熊谷 真一(1,2)、松村 茜(2)、白松-磯口 知世(2)、川合 謙介(1)、高橋 宏知(2)
1. 自治医科大学大学院医学研究科、2. 東京大学大学院情報理工学系研究科
*Shinichi Kumagai(1,2), Akane Matsumura(2), Tomoyo I Shiramatsu(2), Kensuke Kawai(1), Hirokazu Takahashi(2)
1. Grad Sch Med, Jichi Med Univ, Tochigi, Japan, 2. Grad Sch Info Sci and Tech, Univ of Tokyo, Tokyo, Japan
Keyword: VAGUS NERVE STIMULATION, AUDITORY CORTEX, ERP
Vagus nerve stimulation (VNS) is an electrical stimulation therapy targeting the vagus nerve, one of the representative nerves of the autonomic nervous system, and has been used worldwide mainly as a palliative treatment for intractable epilepsy. VNS is likely to affect perception and cognition as a secondary effect, the mechanism of which still remains unknown. In this study, hypothesizing that VNS modulates neural representation at the level of sensory cortex, we investigated the effects of VNS on the auditory cortex using a microelectrode array. Wistar rats (9-12 weeks old, 12 rats in the VNS group and 12 rats in the control group) were used in this study. Rats were anesthetized with isoflurane during the surgery and recording. The neural activity of the auditory cortex was measured using a microelectrode array with 64 recording sites. A click was delivered as a test stimulus once a second. In the VNS group, intermittent electrical stimulation (output current 0.5mA; signal frequency 30Hz; pulse width 130μs; on time 30s; and off time 5min) was applied to the vagus nerve. Noradrenergic and cholinergic antagonists were administered to the auditory cortex to reveal the neural mechanisms of action of VNS. VNS increased the amplitude of the first positive peak (P1) in the auditory evoked potentials (AEPs) and the power in the high frequency band within 30ms after the presentation of the click sound. At 100-150ms after the stimulus onset, VNS increased the power in the high frequency band without significant change in the maximum amplitude of AEPs. The VNS-induced increase in the AEP amplitude and power in the high frequency band were not observed with either noradrenergic or cholinergic antagonists. The results suggest that VNS enhanced onset responses and high-frequency activities in the auditory cortex through noradrenergic and cholinergic neurons. | | 2022年7月3日 9:30～9:45 沖縄コンベンションセンター 会議場A2 第7会場
4O07m1-03
A parallel channel of state-dependent sensory signaling from the cholinergic basal forebrain to the auditory cortex
*Fangchen Zhu(1), Sarah Elnozahy(2), Jennifer Lawlor(1), Kishore Kuchibhotla(1,3)
1. Dept Psych and Brain Sci, Johns Hopkins Univ, Baltimore, Maryland, USA, 2. Sainsbury Wellcome Centre, London, UK, 3. Dept of Neuro, Johns Hopkins Sch of Med, Baltimore, Maryland, USA
Keyword: Cholinergic signaling, Neuromodulation, Two-photon imaging, Sensory system
The cholinergic basal forebrain (CBF) projects extensively to the auditory cortex (ACx). Previous studies have observed intrinsic sensory-evoked responses in CBF neurons but little is known about the characteristics of sensory information relayed by the CBF to the ACx. We asked if cholinergic axonal projections to the ACx provide a parallel pathway for stimulus-specific auditory information to reach the ACx. Using simultaneous two-color, two-photon imaging, we examined sound-evoked responses of CBF axons and cortical neurons in the ACx of head-fixed mice passively listening to a suite of auditory stimuli. We observed robust non-habituating phasic responses of CBF axons to the neutral auditory stimuli. These cholinergic transients were negatively correlated to baseline tonic cholinergic activity – a proxy for the behavioral state of the animal, suggesting a potential self-regulating mechanism for sensory-evoked neuromodulation. Interestingly, individual axon segments exhibited stable heterogenous responses to pure tones and complex sound which allowed for the identity of the auditory stimulus to be accurately decoded from network-wide cholinergic activity. Despite this microscopic heterogeneity, we observed no evidence of tonotopy in CBF projections to the primary ACx, which is in stark contrast to the distinctive tonotopy of cortical neurons in primary ACx. Our two-color imaging approach also revealed that the tuning of axon segments and nearby cortical neurons was uncoupled – the ACx receives two dissimilar auditory signals from the feedforward auditory pathway and the CBF which may act as a potential substrate to drive receptive field plasticity. Finally, using chemogenetic inactivation of the auditory thalamus while imaging CBF axons in the ACx, we demonstrated that inactivation of the auditory thalamus significantly dampened responsiveness of CBF axons.
Our work proposes a novel, non-canonical function for the CBF in which the basal forebrain receives auditory input from the auditory thalamus, modulates these signals based on brain state, and then projects the multiplexed signal to the ACx through a parallel pathway. These signals are temporally-synchronous with cortical responses but differ in their underlying tuning, thus providing a potential mechanism to influence cortical sensory representations during learning and task engagement. | | 2022年7月3日 9:45～10:00 沖縄コンベンションセンター 会議場A2 第7会場
4O07m1-04
時間残効のフォーマット依存性および空間選択性の検討
Format-dependent and spatially non-selective aftereffects induced by time adaptation
*林 正道(1,2)、天野 薫(1,2,3)
1. 情報通信研究機構未来ICT研究所脳情報通信融合研究センター、2. 大阪大学大学院生命機能研究科、3. 東京大学大学院情報理工学系研究科
*Masamichi J Hayashi(1,2), Kaoru Amano(1,2,3)
1. Center for Information and Neural Networks (CiNet), Advanced ICT Research Institute, National Institute for Information and Communications Technology, Suita, Japan, 2. Graduate School of Frontier Biosciences, Osaka University, Suita, Japan, 3. Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan
Keyword: time perception, adaptation, aftereffects
Humans and animals optimize their behavior based on the history of temporal experiences. Time intervals between onset and offset of a single continuous event (i.e., filled interval) and those between multiple brief events (i.e., empty interval) are two typical formats that shape our temporal experiences. However, it is still controversial whether time intervals are represented in an abstract, format-independent manner or rather redundant, format-dependent manner. To address this question, we performed a series of psychophysical experiments and tested whether adaptation to filled and empty intervals affect perceived intervals presented by the same or different stimulus format. In the adaptation phase, participants were adapted to filled or empty intervals of visual stimuli (200 or 700 ms), repeatedly presented forty times. Following the adaptation phase, an auditory reference (450 ms) followed by a visual test stimulus (300 - 600 ms) was presented in the same or different format as the adapting stimuli. Participants judged which one of the two intervals, auditory reference or visual test stimulus, lasted longer. The results showed that perceived time intervals of the test stimuli shifted away from the adapted intervals when the adaptor and test stimuli were presented in the same format, with greater aftereffect magnitude in filled than empty interval condition (Experiment 1). By contrast, the aftereffects were absent when adaptor and test stimuli were presented in different formats (Experiment 2). To identify at which stage of visual processing is involved in perception of each temporal format, we next examined the spatial selectivity of the aftereffect by manipulating the spatial locations of the adaptor and test stimulus presentations (Experiment 3). Crucially, the effect of adaptation fully transferred across the hemifield for both formats, suggesting that time-tuned neural populations for filled and empty intervals may exist at the relatively high level of visual processing hierarchy. Taken together, our findings indicate that filled and empty intervals may be represented by different populations of neurons both located at the higher level of visual processing, although a similar coding scheme (e.g., population coding by interval-tuned cells) may be involved. | |
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