Department of Physiology, Wakayama Medical University, Wakayama, Japan.
Eur J Neurosci. 2024 Oct;60(7):5621-5657. doi: 10.1111/ejn.16510. Epub 2024 Aug 27.
The ventral posterolateral nucleus (VPL), being categorized as the first-order thalamic nucleus, is considered to be dedicated to uni-modal somatosensory processing. Cross-modal sensory interactions on thalamic reticular nucleus cells projecting to the VPL, on the other hand, suggest that VPL cells are subject to cross-modal sensory influences. To test this possibility, the effects of auditory or visual stimulation on VPL cell activities were examined in anaesthetized rats, using juxta-cellular recording and labelling techniques. Recordings were obtained from 70 VPL cells, including 65 cells responsive to cutaneous electrical stimulation of the hindpaw. Auditory or visual alone stimulation did not elicit cell activity except in three bi-modal cells and one auditory cell. Cross-modal alterations of somatosensory response by auditory and/or visual stimulation were recognized in 61 cells with regard to the response magnitude, latency (time and jitter) and/or burst spiking properties. Both early (onset) and late responses were either suppressed or facilitated, and de novo cell activity was also induced. Cross-modal alterations took place depending on the temporal interval between the preceding counterpart and somatosensory stimulations, the intensity and frequency of sound. Alterations were observed mostly at short intervals (< 200 ms) and up to 800 ms intervals. Sounds of higher intensities and lower frequencies were more effective for modulation. The susceptibility to cross-modal influences was related to cell location and/or morphology. These and previously reported similar findings in the auditory and visual thalamic nuclei suggest that cross-modal sensory interactions pervasively take place in the first-order sensory thalamic nuclei.
腹后外侧核（VPL），归类为一级丘脑核，被认为专门用于单一模态的躯体感觉处理。另一方面，投射到 VPL 的丘脑网状核细胞的跨模态感觉相互作用表明，VPL 细胞受到跨模态感觉的影响。为了检验这种可能性，在麻醉大鼠中使用细胞外记录和标记技术，检查了听觉或视觉刺激对 VPL 细胞活动的影响。从 70 个 VPL 细胞中记录到，包括 65 个对后足皮肤电刺激有反应的细胞。除了三个双模态细胞和一个听觉细胞外，听觉或视觉单独刺激不会引起细胞活动。在 61 个细胞中，通过听觉和/或视觉刺激对躯体感觉反应进行了跨模态改变，涉及反应幅度、潜伏期（时间和抖动）和/或爆发性 spike 属性。早期（起始）和晚期反应均被抑制或促进，并且还诱导了新的细胞活动。跨模态改变取决于前一个对应刺激和躯体感觉刺激之间的时间间隔、声音的强度和频率。改变主要发生在短间隔（<200ms）和长达 800ms 的间隔内。强度较高和频率较低的声音更有效进行调制。对跨模态影响的敏感性与细胞位置和/或形态有关。这些以及以前在听觉和视觉丘脑核中报告的类似发现表明，跨模态感觉相互作用普遍存在于一级感觉丘脑核中。
