Instituto de Neurociencias de Alicante, Universidad Miguel Hernández (UMH) - el Consejo Superior de Investigaciones Científicas (CSIC), Campus de San Juan, Sant Joan d'Alacant, Alicante, Spain.
PLoS One. 2006 Dec 27;1(1):e137. doi: 10.1371/journal.pone.0000137.
Neurons throughout the rat vibrissa somatosensory pathway are sensitive to the angular direction of whisker movement. Could this sensitivity help rats discriminate stimuli? Here we use a simple computational model of cortical neurons to analyze the robustness of directional selectivity. In the model, directional preference emerges from tuning of synaptic conductance amplitude and latency, as in recent experimental findings. We find that directional selectivity during stimulation with random deflection sequences is strongly dependent on the mean deflection frequency: Selectivity is weakened at high frequencies even when each individual deflection evokes strong directional tuning. This variability of directional selectivity is due to generic properties of synaptic integration by the neuronal membrane, and is therefore likely to hold under very general physiological conditions. Our results suggest that directional selectivity depends on stimulus context. It may participate in tasks involving brief whisker contact, such as detection of object position, but is likely to be weakened in tasks involving sustained whisker exploration (e.g., texture discrimination).
大鼠触须感觉通路中的神经元对触须运动的角度方向敏感。这种敏感性有助于老鼠辨别刺激吗？在这里，我们使用皮层神经元的简单计算模型来分析方向选择性的稳健性。在该模型中，正如最近的实验结果所示，突触电导幅度和延迟的调谐产生了方向偏好。我们发现，在随机偏转角序列刺激期间的方向选择性强烈依赖于平均偏转角频率：即使每个单独的偏转角引起强烈的方向调谐，在高频时选择性也会减弱。这种方向选择性的可变性是由于神经元膜的突触整合的通用特性引起的，因此很可能在非常一般的生理条件下成立。我们的结果表明，方向选择性取决于刺激环境。它可能参与涉及短暂触须接触的任务，例如检测物体位置，但在涉及持续触须探索的任务（例如纹理识别）中可能会减弱。
