Grunewald A, Linden J F, Andersen R A
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
J Neurophysiol. 1999 Jul;82(1):330-42. doi: 10.1152/jn.1999.82.1.330.
The lateral intraparietal area (LIP) of macaques has been considered unresponsive to auditory stimulation. Recent reports, however, indicate that neurons in this area respond to auditory stimuli in the context of an auditory-saccade task. Is this difference in auditory responsiveness of LIP due to auditory-saccade training? To address this issue, LIP responses in two monkeys were recorded at two different times: before and after auditory-saccade training. Before auditory-saccade training, the animals had never been trained on any auditory task, but had been trained on visual tasks. In both sets of experiments, activity of LIP neurons was recorded while auditory and visual stimuli were presented and the animals were fixating. Before training, 172 LIP neurons were recorded. Among these, the number of cells responding to auditory stimuli did not reach significance, whereas about one-half of the cells responded to visual stimuli. An information theory analysis confirmed that no information about auditory stimulus location was available in LIP neurons in the experiments before training. After training, activity from 160 cells was recorded. These experiments showed that 12% of cells in area LIP responded to auditory stimuli, whereas the proportion of cells responding to visual stimuli remained about the same as before training. The information theory analysis confirmed that, after training, information about auditory stimulus location was available in LIP neurons. Auditory-saccade training therefore generated responsiveness to auditory stimuli de novo in LIP neurons. Thus some LIP cells become active for auditory stimuli in a passive fixation task, once the animals have learned that these stimuli are important for oculomotor behavior.
猕猴的外侧顶内区（LIP）一直被认为对听觉刺激无反应。然而，最近的报告表明，该区域的神经元在听觉扫视任务的背景下对听觉刺激有反应。LIP在听觉反应上的这种差异是由于听觉扫视训练吗？为了解决这个问题，在两只猴子身上于两个不同时间记录了LIP的反应：听觉扫视训练之前和之后。在听觉扫视训练之前，这些动物从未接受过任何听觉任务的训练，但接受过视觉任务的训练。在两组实验中，当呈现听觉和视觉刺激且动物处于注视状态时，记录LIP神经元的活动。训练前，记录了172个LIP神经元。其中，对听觉刺激有反应的细胞数量未达到显著水平，而约一半的细胞对视觉刺激有反应。信息论分析证实，在训练前的实验中，LIP神经元中没有关于听觉刺激位置的信息。训练后，记录了160个细胞的活动。这些实验表明，LIP区域中12%的细胞对听觉刺激有反应，而对视觉刺激有反应的细胞比例与训练前大致相同。信息论分析证实，训练后，LIP神经元中有关于听觉刺激位置的信息。因此，听觉扫视训练在LIP神经元中重新产生了对听觉刺激的反应性。这样一来，一旦动物了解到这些刺激对眼球运动行为很重要，一些LIP细胞在被动注视任务中就会对听觉刺激变得活跃。
