Sanz-Leon Paula, Robinson P A
School of Physics, University of Sydney, NSW 2006, Australia; Center for Integrative Brain Function, University of Sydney, NSW 2006, Australia.
School of Physics, University of Sydney, NSW 2006, Australia; Center for Integrative Brain Function, University of Sydney, NSW 2006, Australia.
J Theor Biol. 2017 Nov 7;432:141-156. doi: 10.1016/j.jtbi.2017.07.015. Epub 2017 Aug 19.
Neural field theory of the corticothalamic system is used to analyze the properties of its steady-state solutions, including their linear stability, in the parameter space of synaptic couplings for physiological parameter ranges representing normal arousal waking states in adult humans. The independent connections of the corticothalamic model define an eight-dimensional parameter space, while specific combinations of these connections parameterize intracortical, corticothalamic, and intrathalamic loops. Multistable regions are systematically identified and the existence of up to five steady-state solutions is confirmed, up to three of which are linearly stable. A key determinant for the existence of five steady states is found to be the number of nonzero connections. This finding had not been previously proposed as the determining factor of high multiplicities of multistability in mesoscopic models of the brain. In the corticothalamic model presented here, multistability occurs when the intrathalamic loop is present (i.e., the reticular nucleus inhibits the relay nuclei), and when the net synaptic effect of the intracortical loop is inhibitory. The signature of these additional waking states is an overall increased level of thalamic activity. It is argued that the additional steady states found may represent hyperarousal states which occur when the corticothalamic projections do not attenuate the activity of the cortex.
皮质丘脑系统的神经场理论被用于分析其稳态解的性质，包括在代表成年人类正常觉醒状态的生理参数范围内突触耦合参数空间中的线性稳定性。皮质丘脑模型的独立连接定义了一个八维参数空间，而这些连接的特定组合对皮质内、皮质丘脑和丘脑内环路进行参数化。系统地识别出多稳态区域，并确认存在多达五个稳态解，其中多达三个是线性稳定的。发现存在五个稳态的一个关键决定因素是非零连接的数量。这一发现此前并未被提议作为大脑介观模型中多稳定性高多重性的决定因素。在此呈现的皮质丘脑模型中，当丘脑内环路存在时（即网状核抑制中继核），以及当皮质内环路的净突触效应为抑制性时，会出现多稳态。这些额外觉醒状态的特征是丘脑活动水平总体增加。有人认为，发现的额外稳态可能代表当皮质丘脑投射不减弱皮质活动时出现的过度觉醒状态。
