Encoding of temporal intervals in the rat hindlimb sensorimotor cortex.
Encoding of temporal intervals in the rat hindlimb sensorimotor cortex.
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DOI：
10.3389/fnsys.2012.00067
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发表时间：
2012
影响因子：
3
通讯作者：
Moxon KA
中科院分区：
文献类型：
--
作者：
Knudsen EB;Flint RD;Moxon KA
在实验施加的延迟期内，神经活动逐渐积累，称为攀爬活动，这是有据可查的，是一种潜在的机制，通过这种机制，间隔时间被大脑中分布的皮质-丘脑-纹状体网络编码。此外，当多个延迟周期被合并时，该活动已被证明与延迟周期成比例地缩放其爬升速率。然而，目前还不清楚这些活动模式是否发生在专门用于后肢运动的运动皮层区域内。此外，行为训练的效果（例如，运动任务）但具有相似的行为输出。为了解决这一问题，我们记录了两组大鼠的后肢感觉运动皮层（HLSMC）的活动，这些大鼠执行熟练的后肢按压任务。在第一组中，大鼠只训练在提示呈现奖励后的有限窗口内进行有效按压（非间隔训练，n = 5），而第二组中的大鼠给予持续时间特定的提示，其中它们必须进行短时间或长时间的按压以获得奖励（间隔训练，IT; n = 6）。使用围事件时间直方图（PETH）分析，我们发现，从两组记录的细胞显示攀爬活动在任务期间的比例相似（35%IT和47%nIT），但是，只有攀爬活动从IT大鼠按时间缩放到按持续时间。此外，使用单次试验解码技术（维纳滤波器），我们表明，可以使用IT动物的攀爬活动（R = 0.61）推断按压持续时间，显著优于nIT动物（R = 0.507，p < 0.01），表明IT动物通过时间尺度的攀爬活动编码按压持续时间。因此，如果时间间隔与行为相关，则攀爬神经元的活动在时间上被缩放以编码时间的流逝。
The gradual buildup of neural activity over experimentally imposed delay periods, termed climbing activity, is well documented and is a potential mechanism by which interval time is encoded by distributed cortico-thalamico-striatal networks in the brain. Additionally, when multiple delay periods are incorporated, this activity has been shown to scale its rate of climbing proportional to the delay period. However, it remains unclear whether these patterns of activity occur within areas of motor cortex dedicated to hindlimb movement. Moreover, the effects of behavioral training (e.g., motor tasks) under different reward conditions but with similar behavioral output are not well addressed. To address this, we recorded activity from the hindlimb sensorimotor cortex (HLSMC) of two groups of rats performing a skilled hindlimb press task. In one group, rats were trained only to a make a valid press within a finite window after cue presentation for reward (non-interval trained, nIT; n = 5), while rats in the second group were given duration-specific cues in which they had to make presses of either short or long duration to receive reward (interval trained, IT; n = 6). Using perievent time histogram (PETH) analyses, we show that cells recorded from both groups showed climbing activity during the task in similar proportions (35% IT and 47% nIT), however, only climbing activity from IT rats was temporally scaled to press duration. Furthermore, using single trial decoding techniques (Wiener filter), we show that press duration can be inferred using climbing activity from IT animals (R = 0.61) significantly better than nIT animals (R = 0.507, p < 0.01), suggesting IT animals encode press duration through temporally scaled climbing activity. Thus, if temporal intervals are behaviorally relevant then the activity of climbing neurons is temporally scaled to encode the passage of time.