Arce-McShane Fritzie I, Sessle Barry J, Ram Yasheshvini, Ross Callum F, Hatsopoulos Nicholas G
Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, United States.
Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States.
Front Syst Neurosci. 2023 Sep 22;17:1213279. doi: 10.3389/fnsys.2023.1213279. eCollection 2023.
The precise control of bite force and gape is vital for safe and effective breakdown and manipulation of food inside the oral cavity during feeding. Yet, the role of the orofacial sensorimotor cortex (OSMcx) in the control of bite force and gape is still largely unknown. The aim of this study was to elucidate how individual neurons and populations of neurons in multiple regions of OSMcx differentially encode bite force and static gape when subjects generated different levels of bite force at varying gapes. We examined neuronal activity recorded simultaneously from three microelectrode arrays implanted chronically in the primary motor (MIo), primary somatosensory (SIo), and cortical masticatory (CMA) areas of OSMcx. We used generalized linear models to evaluate encoding properties of individual neurons and utilized dimensionality reduction techniques to decompose population activity into components related to specific task parameters. Individual neurons encoded bite force more strongly than gape in all three OSMCx areas although bite force was a better predictor of spiking activity in MIo vs. SIo. Population activity differentiated between levels of bite force and gape while preserving task-independent temporal modulation across the behavioral trial. While activation patterns of neuronal populations were comparable across OSMCx areas, the total variance explained by task parameters was context-dependent and differed across areas. These findings suggest that the cortical control of static gape during biting may rely on computations at the population level whereas the strong encoding of bite force at the individual neuron level allows for the precise and rapid control of bite force.
在进食过程中，精确控制咬合力和张口度对于在口腔内安全有效地分解和处理食物至关重要。然而，口面部感觉运动皮层（OSMcx）在控制咬合力和张口度方面的作用仍 largely unknown。本研究的目的是阐明当受试者在不同张口度下产生不同水平的咬合力时，OSMcx多个区域的单个神经元和神经元群体如何差异编码咬合力和静态张口度。我们检查了长期植入OSMcx的初级运动区（MIo）、初级体感区（SIo）和皮质咀嚼区（CMA）的三个微电极阵列同时记录的神经元活动。我们使用广义线性模型来评估单个神经元的编码特性，并利用降维技术将群体活动分解为与特定任务参数相关的成分。在所有三个OSMCx区域中，单个神经元对咬合力的编码比对张口度的编码更强，尽管咬合力在MIo与SIo中是尖峰活动的更好预测指标。群体活动在咬合力和张口度水平之间进行区分，同时在行为试验中保留与任务无关的时间调制。虽然神经元群体的激活模式在OSMCx区域之间具有可比性，但任务参数解释的总方差取决于上下文且在不同区域有所不同。这些发现表明，咬合过程中静态张口度的皮层控制可能依赖于群体水平的计算，而单个神经元水平对咬合力的强编码允许对咬合力进行精确和快速的控制。
