SI CORTICAL RESPONSE TO CUTANEOUS FLUTTER VIBRATION

说明(改编自调查员摘要)：建议的 研究的目的是扩展目前关于这种机制的信息 负责对振动触觉的频率和幅度进行编码 刺激物。尽管可控震击一直是众多 心理物理和神经生理学检查，以及具体的 20年前，拉莫特和芒特卡斯尔提出了假说。 用于振动触觉刺激频率的皮质群体代码和 幅度，到目前为止还没有研究直接成像全球 对振动触觉刺激的初级体感皮质反应，或 该响应对其对后续输入驱动响应的影响。 体感皮质反应的全球模式也不是 有效地与其单个神经元的行为有关。在 拟议的研究将通过使用四种类型的 在猫身上制作的录音和已知的刺激条件 人类的振动触觉适应。在每个实验中， 关于SI前爪整体反应模式的前向活动 大脑皮质到受控的振动触觉刺激将首先表征 在高时间和空间分辨率下使用近红外(IR； 在730 850 nm处的反射率)本征信号的光学成像。 然后，微电极穿透将在凸起的 总体IR活动模式的区域。微电极 穿透将提供以下两种样本：(I)刺激诱发和 细胞外记录的自发棘波放电活动 单个神经元，和(Ii)局部场电位(LFP)反映 小神经元聚集体的总和活性。 检测和控制与刺激相关的可能贡献 皮肤机械感受性传入反应性的变化， 将同时记录刺激诱发的MRA抽射 出去。对记录的神经电数据的分析将使用各种 新程序的设计，以便于测量众所周知的 与有节奏的皮肤刺激相关的神经活动的夹带。 申请者的初步研究表明，这部小说 要使用的程序产生编码的有用的单次试验措施 由单个SI神经元和 MRA人群。以下是对时间依赖关系的描述 大脑皮层IR和SU响应，以及MRA群体对 已知的与以下因素相关的振动触觉刺激条件 在人类的知觉适应方面，他们将研究 静脉或局部给药的时间依赖性 已知通过选择性作用改变谷氨酸能神经传递 NMDA受体(氯胺酮、苯环利定和AP-5)。都是试验性的 调查结果将根据其与 申请者的工作模式是刺激诱发的，NMDA受体依赖的， 躯体感觉皮质内的皮质相互作用-一个模型 结合了连接细节和神经递质 新大脑皮层所有区域共有的机制。这项研究是 预计将直接导致对机制的更好理解 在SI中对振动触觉刺激进行编码，并在较长期内帮助 阐明在不同情况下涉及的皮质机制 精神分裂症和各种形式的药物滥用。

DESCRIPTION (Adapted from the Investigator's Abstract): The proposed research is designed to extend current information about the mechanisms responsible for encoding the frequency and amplitude of vibrotactile stimuli. Although vibrotaction has been the subject of numerous psychophysical and neurophysiological investigations, and specific hypotheses were advanced twenty years ago by LaMotte and Mountcastle as to the cortical population codes for vibrotactile stimulus frequency and amplitude, no study to date has directly imaged either the global primary somatosensory cortical response to vibrotactile stimulation, or the effect of that response on its response to subsequent input drive. Nor has the global pattern of somatosensory cortical response been related effectively to the behavior of its individual neurons. In the proposed research these objectives will be met by using four types of recordings made in cats and stimulus conditions known to produce vibrotactile adaptation in humans. In each experiment the impact of preceding activity on the global pattern of response of SI forepaw cortex to a controlled vibrotactile stimulus will first be characterized at high temporal and spatial resolution using near-infrared (IR; reflectance at 730 850 nm) optical imaging of intrinsic signals. Microelectrode penetrations will then be carried out within salient regions of the overall IR activity pattern. The microelectrode penetrations will provide samples of both (i) stimulus-evoked and spontaneous spike discharge activity recorded extracellularly from single neurons, and (ii) local field potentials (LFPs) reflecting the summated activity of small neuronal aggregates. To detect and control for possible contributions by stimulus-related changes in the responsivity of skin mechanoreceptive afferents (MRAs), concurrent recordings of the stimulus-evoked MRA volley will be carried out. Analysis of the recorded neuroelectrical data will employ a variety of novel procedures designed to facilitate measurement of the well-known entrainment of neural activity associated with rhythmic skin stimuli. The applicants' preliminary studies have demonstrated that the novel procedures to be used yield useful single trial measures of the coding of vibrotactile stimulus parameters by both single SI neurons and the MRA population. Following characterization of the time-dependencies of the cortical IR and SU responses, and of the MRA population to conditions of vibrotactile stimulation known to be associated with perceptual adaptation in humans, they will investigate the effects on those time dependencies of intravenous or topical administration of drugs known to modify glutaminergic neurotransmission via selective actions on NMDA receptors (ketamine, phencyclidine, and AP-5). All experimental findings will be assessed in terms of their consistency with the applicants' working model of stimulus-evoked, NMDA receptor-dependent, corticocortical interactions within somatosensory cortex - a model which incorporates connectional details and incorporate neurotransmitter mechanisms common to all regions of neocortex. The research is anticipated to lead directly to improved understanding of the mechanisms of vibrotactile stimulus coding in SI, and in the longer term to help elucidate the cortical mechanisms involved in conditions as diverse as schizophrenia and various forms of substance abuse.