Improved motion perception and impaired spatial suppression following disruption of cortical area MT/V5.
Improved motion perception and impaired spatial suppression following disruption of cortical area MT/V5.
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DOI：
10.1523/jneurosci.4121-10.2011
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发表时间：
2011-01-26
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影响因子：
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通讯作者：
Battelli L
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文献类型：
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作者：
Tadin D;Silvanto J;Pascual-Leone A;Battelli L
随着刺激大小的增加，高对比度图案的运动方向变得越来越难以感知。这种反直觉的行为结果，被称为“空间抑制”，被假设为反映了中心-周围对抗-一种在感觉系统中普遍存在的感受场特性。先前的研究表明，运动信号的空间抑制与皮层区MT的中心-周围拮抗直接相关。在这里，我们研究了人类MT/V5是否确实与运动信号的空间抑制有因果关系。关键的假设是，在空间抑制中起关键作用的神经机制的破坏可能使这些通常被抑制的运动信号达到知觉意识。因此，我们的假设是，MT/V5的中断应该削弱空间抑制，从而改善大型运动模式的运动感知。为了破坏MT/V5，我们使用离线1Hz经颅磁刺激(TMS) -一种暂时减弱目标皮层正常功能的方法。早期的视觉区域也被作为控制区域。结果支持了我们的假设，并表明MT/V5的破坏可能通过削弱周围抑制强度来改善对大型运动刺激的运动辨别。这种效应仅针对MT/V5刺激和对侧呈现的刺激。显然，限制大的、高对比度刺激的运动知觉的关键神经约束包括MT/V5。此外，我们的研究结果模拟了在一些患者群体中观察到的空间抑制缺陷，并暗示MT/V5过程受损可能与老年人、精神分裂症患者和有抑郁症病史的患者报告的感知异常有关。
As stimulus size increases, motion direction of high-contrast patterns becomes increasingly harder to perceive. This counterintuitive behavioral result, termed “spatial suppression,” is hypothesized to reflect center-surround antagonism – a receptive field property ubiquitous in sensory systems. Prior research proposed that spatial suppression of motion signals is a direct correlate of center-surround antagonism within cortical area MT. Here, we investigated whether human MT/V5 is indeed causally involved in spatial suppression of motion signals. The key assumption is that a disruption of neural mechanisms that play a critical role in spatial suppression could allow these normally suppressed motion signals to reach perceptual awareness. Thus, our hypothesis was that a disruption of MT/V5 should weaken spatial suppression and, consequently, improve motion perception of large, moving patterns. To disrupt MT/V5, we utilized offline 1Hz transcranial magnetic stimulation (TMS) – a method that temporarily attenuates normal functioning of the targeted cortex. Early visual areas were also targeted as a control site. The results supported our hypotheses and showed that disruption of MT/V5 improved motion discrimination of large, moving stimuli, presumably by weakening surround suppression strength. This effect was specific to MT/V5 stimulation and contralaterally presented stimuli. Evidently, the critical neural constraints limiting motion perception of large, high-contrast stimuli involve MT/V5. Additionally, our findings mimic spatial suppression deficits that are observed in several patient populations and implicate impaired MT/V5 processes as likely neural correlates for the reported perceptual abnormalities in the elderly, patients with schizophrenia and those with a history of depression.