Integrative Multisensory Perception Action & Cognition Team (ImpAct), Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France; Hospices Civils de Lyon, Neuro-immersion & Mouvement et Handicap, Lyon, France.
Integrative Multisensory Perception Action & Cognition Team (ImpAct), Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France; Hospices Civils de Lyon, Neuro-immersion & Mouvement et Handicap, Lyon, France; Department of Psychology, University of Bologna, Bologna, Italy.
Cortex. 2017 Dec;97:23-31. doi: 10.1016/j.cortex.2017.09.015. Epub 2017 Oct 3.
Rightward prismatic adaptation (RPA) can reduce neglect symptoms in patients whereas adaptation to leftward deviating prisms (LPA) can induce neglect-like behavior in healthy subjects. One influential anatomo-functional model of prismatic adaptation (PA) postulates that it inhibits activity of the posterior parietal cortex (PPC) contralateral to the prismatic deviation. By hypo-activating the PPC and thus eventually acting on interhemispheric balance, both LPA and RPA could possibly affect visuospatial perception in healthy subjects, however, such behavioral modulation has seldom been reported after RPA. In the light of recent evidence showing that LPA-induced visuospatial shift need time to develop we hypothesized that RPA might induce significant changes in visuospatial cognition on a longer time scale. We thus assessed the Landmark task, as well as sensorimotor aftereffects, several times over 8 h after a single session of either LPA or RPA. In agreement with previous reports, sensorimotor effects were symmetrical and long-lasting, with both LPA and RPA inducing shifts of comparable amplitudes in the direction opposite to the deviation that lasted up to 8 h. Visuospatial cognition assessed by Landmark performance, was also significantly modulated for up to 8 h, but only after LPA. Interestingly, the timing and direction of this modulation differed according to participants' baseline bias. An initial leftward bias led to a rapid, but short-lasting rightward shift, whereas an initial rightward bias led to a slower-developing and longer-lasting leftward shift. These findings shed new light on a so-far relatively overlooked feature of spatial cognition that may interact with the effect of PA: the state of the visuospatial system prior to PA should be taken into account when attempting to understand and modulate visuospatial cognition in healthy and brain-damaged populations. This highlights the need for refining current models of PA's mechanisms of action.
右侧棱镜片适应（RPA）可减少患者的忽视症状，而适应左侧偏斜棱镜片（LPA）可在健康受试者中引起类似忽视的行为。一种有影响力的棱镜片适应（PA）的解剖-功能模型假设，它抑制了与棱镜片偏差相对侧的后顶叶皮层（PPC）的活动。通过对 PPC 的低激活，最终影响到大脑两半球间的平衡，LPA 和 RPA 都可能影响健康受试者的视空间感知，然而，这种行为调节在 RPA 后很少被报道。鉴于最近的证据表明，LPA 诱导的视空间转移需要时间来发展，我们假设 RPA 可能会在更长的时间尺度上引起视空间认知的显著变化。因此，我们在单次 LPA 或 RPA 后 8 小时内多次评估了地标任务以及感觉运动后效。与之前的报告一致，感觉运动效应是对称且持久的，LPA 和 RPA 都在与偏差相反的方向上诱导了相当幅度的移位，持续时间长达 8 小时。地标任务的视空间认知评估也显著受到影响，持续时间长达 8 小时，但仅在 LPA 后。有趣的是，这种调节的时间和方向根据参与者的基线偏差而有所不同。初始的左偏导致快速但短暂的右移，而初始的右偏导致较慢发展和持久的左移。这些发现为空间认知这一迄今为止相对被忽视的特征提供了新的认识，这可能与 PA 的效果相互作用：在试图理解和调节健康和脑损伤人群的视空间认知时，应考虑 PA 之前视空间系统的状态。这凸显了需要细化当前 PA 作用机制模型的必要性。
