Tramonti Fantozzi Maria Paola, De Cicco Vincenzo, Barresi Massimo, Cataldo Enrico, Faraguna Ugo, Bruschini Luca, Manzoni Diego
Department of Translational Research and of New Surgical and Medical Technologies, University of PisaPisa, Italy.
Institut des Maladies Neurodégénératives, University of BordeauxBordeaux, France.
Front Neuroanat. 2017 Aug 8;11:68. doi: 10.3389/fnana.2017.00068. eCollection 2017.
Trigeminal input to the ascending activating system is important for the maintenance of arousal and may affect the discharge of the noradrenergic neurons of the (LC), whose activity influences both vigilance state and pupil size, inducing mydriasis. For this reason, pupil size evaluation is now considered an indicator of LC activity. Since mastication activates trigeminal afferent neurons, the aims of the present study, conducted on healthy adult participants, were to investigate whether chewing a bolus of different hardness may: (1) differentially affect the performance on a cognitive task (consisting in the retrieval of specific target numbers within numerical matrices) and (2) increase the dilatation of the pupil (mydriasis) induced by a haptic task, suggesting a change in LC activation. Results show that chewing significantly increased both the velocity of number retrieval (without affecting the number of errors) and the mydriasis associated with the haptic task, whereas simple task repetition did not modify either retrieval or mydriasis. Handgrip exercise, instead, significantly decreased both parameters. Effects were significantly stronger and longer lasting when subjects chewed hard pellets. Finally, chewing-induced improvements in performance and changes in mydriasis were positively correlated, which suggests that trigeminal signals enhanced by chewing may boost the cognitive performance by increasing LC activity.
三叉神经向升支激活系统的输入对于维持觉醒很重要，并且可能影响蓝斑（LC）去甲肾上腺素能神经元的放电，其活动会影响警觉状态和瞳孔大小，导致瞳孔散大。因此，瞳孔大小评估现在被认为是蓝斑活动的一个指标。由于咀嚼会激活三叉神经传入神经元，本研究以健康成年参与者为对象，旨在调查咀嚼不同硬度的一团食物是否会：（1）对认知任务（即在数字矩阵中检索特定目标数字）的表现产生不同影响；（2）增加触觉任务诱发的瞳孔扩张（瞳孔散大），这表明蓝斑激活发生了变化。结果显示，咀嚼显著提高了数字检索速度（不影响错误数量）以及与触觉任务相关的瞳孔散大，而简单的任务重复并未改变检索或瞳孔散大情况。相反，握力锻炼显著降低了这两个参数。当受试者咀嚼硬颗粒时，效果显著更强且持续时间更长。最后，咀嚼引起的表现改善和瞳孔散大变化呈正相关，这表明咀嚼增强的三叉神经信号可能通过增加蓝斑活动来提高认知表现。
