Non-invasive brain stimulation approaches to visual system modeling and plasticity

非侵入性脑刺激方法，如经颅磁刺激（TMS）和经颅磁刺激（TMT）。 电刺激（TES）可用于两个目的，每个目的在基础视觉中具有广泛的应用 神经科学和视觉康复。在第一种情况下，刺激被用来操纵活动， 皮层网络，目标是理解目标网络在生成大脑中的因果作用 反应和感知/行为。在第二种情况下，刺激被用于神经调节作用，以诱导 皮质网络的可塑性重塑，无论是在短期还是长期的基础上。这项建议的重点是 开发新的实验系统，将视觉和电刺激相结合， 这些目标。这项研究的中心假设是经颅交流电刺激（TACS）， TES的一种变体，通过TACS场与细胞内 极化神经元的膜电位。这一假设和相关的假设，即短期 TACS的持续影响将与在线测量的影响成比例，将使用 结合功能性磁共振成像（FMRI）、稳态视觉诱发电位 （SSVEP）和感知报告。中心假设的基本原理基于以下几个观察结果： 第一，周期性视觉刺激产生视觉反应（SSVEP），这些视觉反应直接和精确地与 刺激频率。其次，由于TACS也是周期性的，并且是极窄带的，因此它应该是 可以通过突触电位和电位的总和直接针对周期性视觉反应本身 在任务活跃的神经元中。最后，由于先前的工作表明，外部施加的电场 主要调节细长的神经元，预测TAC的作用取决于 皮质组织和所施加的TACS场的方向。这一核心假设将在目标1中得到检验， 确定BOLD对视觉对比度的反应是否取决于TACS和视觉对比度的相对相位， 刺激以及皮质表面和所施加场的相对取向。目标2将测试 在双眼竞争和双眼倾斜辨别期间使用SSVEP和知觉报告的假设 任务目标1还将使用功能磁共振成像来确定刺激关闭后TACS效应是否持续，如果是， TACS效应是否取决于视觉和电刺激的相对相位， 如果中心假设是正确的。这项提案的实验将确定是否有两个 来自动物实验模型的TACS有效性的主要假设机制可以是 在人体内进行实验控制。他们还将确定TACS是否会导致短暂的- 长期持续影响视觉反应。该提案中开发的新实验方法 具有在视觉神经科学和眼科学中广泛应用的潜力， 对神经活动施加因果控制，并在复杂的视觉网络中引起可塑性变化。

Non-invasive brain stimulation approaches such as transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) can be used for two purposes, each with wide application in fundamental visual neuroscience and in visual rehabilitation. In the first of these, stimulation is used to manipulate activity in cortical networks with the goal understanding the causal role of the targeted network in generating brain responses and in perception/behavior. In the second, stimulation is used in a neuromodulatory role to induce plastic remodeling of cortical networks, either on a short-term or long-term basis. The focus of this proposal is the development of new experimental systems for combining visual and electrical stimulation that will achieve these goals. The central hypothesis of this research is that Transcranial Alternating Current Stimulation (TACS), a variant of TES, acts via constructive or destructive summation of the TACS field with the intracellular membrane potential of polarizable neurons. This hypothesis and the related hypothesis that short-term persistent effects of TACS will be proportional to the effects measured online will be tested using a combination of Functional Magnetic Resonance Imaging (FMRI), Steady-State Visual Evoked Potentials (SSVEPs) and perceptual reports. The rationale for the central hypothesis is based on several observations: first, periodic visual stimulation generates visual responses (SSVEPs) that are directly and precisely related to the stimulus frequency. Second, because TACS is also periodic and extremely narrowband, it should be possible to directly target the periodic visual response itself via summation of synaptic and electrical potentials within task-active neurons. Finally, because prior work has suggested that externally applied electric fields primarily modulate elongated neurons, the effects of TACs are predicted to depend on both the orientation of the cortical tissue and the direction of the applied TACS field. This central hypothesis will be tested in Aim 1 by determining whether BOLD responses to visual contrast depend on the relative phase of TACS and visual stimulation and the relative orientations of the cortical surface and the applied field. Aim 2 will test the hypothesis using the SSVEP and perceptual reports during binocular rivalry and binocular slant discrimination tasks. Aim 1 will also use FMRI to determine if TACS effects persist after the stimulation is turned off and if so, whether the TACS effect depends on the relative phase of visual and electrical stimulation as would be expected if the central hypothesis is correct. The experiments of this proposal will determine whether two of the main hypothesized mechanisms for TACS effectiveness derived from animal experimental models can be identified and brought under experimental control in human. They will also determine if TACS results in a short- term persistent effect on visual responsiveness. The new experimental approaches developed in this proposal have the potential for wide application in visual neuroscience and ophthalmology via their possible ability to exert causal control over neural activity and to elicit plastic changes in complex visual networks.