Processing of periodic whisker deflections by neurons in the ventroposterior medial and thalamic reticular nuclei
Processing of periodic whisker deflections by neurons in the ventroposterior medial and thalamic reticular nuclei
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DOI：
10.1152/jn.00469.2003
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发表时间：
2003-11-01
影响因子：
2.5
通讯作者：
Simons, DJ
中科院分区：
文献类型：
--
作者：
Hartings, JA;Temereanca, S;Simons, DJ
老鼠利用有节奏的胡须运动来采样其感官环境中的信息。为了研究丘脑回路的频率调谐和过滤特性，我们记录了轻度麻醉大鼠的腹后内侧（VPm）和丘脑网状（Rt）神经元对1至40赫兹正弦和脉动胡须偏转的单单位反应。神经元夹带通过测量刺激频率下放电的相对调制（RM）来评估，该刺激频率由周期时间直方图的一次谐波（F1）除以平均放电率（F0）给出。正弦和周期性脉动胡须运动的 VPm 信号在 1-16 Hz 范围内逐渐改善，并在 20-40 Hz 时达到最大值。相比之下，Rt 响应的 RM 在 1-8 Hz 范围内增加，但在 12-40 Hz 范围内逐渐恶化。在 Rt 中，反应适应发生在较低的刺激频率下，并且比 VPm 中的反应适应程度更大。在一系列高频刺激中，Rt 反应逐渐减弱，这可能是由于抑制的积累，而 VPm 神经元的反应则增强。 Rt 的平均放电率在 1-40 Hz 范围内增加了 42 个尖峰/秒，在高频刺激期间提供强直（低 RM）抑制，可能会增强 VPm 信噪比。与这一观点一致，VPm 平均放电率在 1-40 Hz 范围内仅增加 13 个尖峰/秒，并且偏转间活动比刺激诱发的反应受到更大程度的抑制。 Rt 抑制可能与神经调节剂的作用协同作用，优化高频胡须运动的丘脑时间信号传导。
Rats employ rhythmic whisker movements to sample information in their sensory environment. To study frequency tuning and filtering characteristics of thalamic circuitry, we recorded single-unit responses of ventroposterior medial (VPm) and thalamic reticular (Rt) neurons to 1- to 40-Hz sinusoidal and pulsatile whisker deflection in lightly narcotized rats. Neuronal entrainment was assessed by a measure of the relative modulation (RM) of firing at the stimulus frequency given by the first harmonic (F1) of the cycle time histogram divided by the mean firing rate (F0). VPm signaling of both sinusoidal and periodic pulsatile whisker movements improved gradually over 1-16 and was maximal at 20-40 Hz. By contrast, the RM of Rt responses increased over 1-8 Hz, but deteriorated progressively over the 12- to 40-Hz range. In Rt, response adaptation occurred at lower stimulus frequencies and to a greater extent than in VPm. Within a train of high-frequency stimuli, Rt responses progressively decremented, possibly due to the accumulation of inhibition, whereas those of VPm neurons augmented. Mean firing rates in Rt increased 42 spikes/s over 1-40 Hz, providing tonic (low RM) inhibition during high-frequency stimulation that may enhance VPm signal-to-noise ratios. Consistent with this view, VPm mean firing rates increased only 13 spikes/s over 1-40 Hz, and inter-deflection activity was suppressed to a greater extent than stimulus-evoked responses. Rt inhibition is likely to act in concert with actions of neuromodulators in optimizing thalamic temporal signaling of high-frequency whisker movements.