cognitive fun!

Gnathology

Neurosci Lett. 2008 May 9;436(2):189-92. Epub 2008 Mar 16.
Effects of chewing in working memory processing.
Hirano Y, Obata T, Kashikura K, Nonaka H, Tachibana A, Ikehira H, Onozuka M.
Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan. hirano@nirs.go.jp
Abstract
It has been generally suggested that chewing produces an enhancing effect on cognitive performance-related aspects of memory by the test battery. Furthermore, recent studies have shown that chewing is associated with activation of various brain regions, including the prefrontal cortex. However, little is known about the relation between cognitive performances affected by chewing and the neuronal activity in specified regions in the brain. We therefore examined the effects of chewing on neuronal activities in the brain during a working memory task using fMRI. The subjects chewed gum, without odor and taste components, between continuously performed two- or three-back (n-back) working memory tasks. Chewing increased the BOLD signals in the middle frontal gyrus (Brodmann's areas 9 and 46) in the dorsolateral prefrontal cortex during the n-back tasks. Furthermore, there were more prominent activations in the right premotor cortex, precuneus, thalamus, hippocampus and inferior parietal lobe during the n-back tasks after the chewing trial. These results suggest that chewing may accelerate or recover the process of working memory besides inducing improvement in the arousal level by the chewing motion.


J Oral Rehabil. 2010 Mar 2. [Epub ahead of print]
Occlusion and brain function: mastication as a prevention of cognitive dysfunction.
Ono Y, Yamamoto T, Kubo KY, Onozuka M.
Department of Physiology and Neuroscience, Kanagawa Dental College, Yokosuka, Japan.
Abstract
Summary Research in animals and humans has shown that mastication maintains cognitive function in the hippocampus, a brain area important for learning and memory. Reduced mastication, an epidemiological risk factor for the development of dementia in humans, attenuates spatial memory and causes hippocampal neurons to deteriorate morphologically and functionally, especially in aged animals. Active mastication rescues the stress-attenuated hippocampal memory process in animals and attenuates the perception of stress in humans by suppressing endocrinological and autonomic stress responses. Active mastication further improves the performance of sustained cognitive tasks by increasing the activation of the hippocampus and the prefrontal cortex, the brain regions that are essential for cognitive processing. Abnormal mastication caused by experimental occlusal disharmony in animals produces chronic stress, which in turn suppresses spatial learning ability. The negative correlation between mastication and corticosteroids has raised the hypothesis that the suppression of the hypothalamic-pituitary-adrenal (HPA) axis by masticatory stimulation contributes, in part, to preserving cognitive functions associated with mastication. In the present review, we examine research pertaining to the mastication-induced amelioration of deficits in cognitive function, its possible relationship with the HPA axis, and the neuronal mechanisms that may be involved in this process in the hippocampus.


Nutr Neurosci. 2010 Feb;13(1):7-16.
Effects of chewing gum on cognitive function, mood and physiology in stressed and non-stressed volunteers.
Smith A.
Centre for Occupational and Health Psychology, School of Psychology, Cardiff University, 63 Park Place, Cardiff, CF10 3AS, UK. smithap@cardiff.ac.uk
Abstract
RATIONALE: Recent research suggests that chewing gum may improve aspects of cognitive function and mood. There is also evidence suggesting that chewing gum reduces stress. It is important, therefore, to examine these two areas and to determine whether contextual factors (chewing habit, type of gum, and personality) modify such effects. OBJECTIVES: The aims of the present study were: (i) to determine whether chewing gum improved mood and mental performance; (ii) to determine whether chewing gum had benefits in stressed individuals; and (iii) to determine whether chewing habit, type of gum and level of anxiety modified the effects of gum. SUBJECTS AND METHODS: A cross-over study involving 133 volunteers was carried out. Each volunteer carried out a test session when they were chewing gum and without gum, with order of gum conditions counterbalanced across subjects. Baseline sessions were conducted prior to each test session. Approximately half of the volunteers were tested in 75 dBA noise (the stress condition) and the rest in quiet. Volunteers were stratified on chewing habit and anxiety level. Approximately, half of the volunteers were given mint gum and half fruit gum. The volunteers rated their mood at the start and end of each session and had their heart rate monitored over the session. Saliva samples were taken to allow cortisol levels (good indicator of alertness and stress) to be assayed. During the session, volunteers carried out tasks measuring a range of cognitive functions (aspects of memory, selective and sustained attention, psychomotor speed and accuracy). RESULTS: Chewing gum was associated with greater alertness and a more positive mood. Reaction times were quicker in the gum condition, and this effect became bigger as the task became more difficult. Chewing gum also improved selective and sustained attention. Heart rate and cortisol levels were higher when chewing which confirms the alerting effect of chewing gum. CONCLUSIONS: Overall, the results suggest that chewing gum produces a number of benefits that are generally observed and not context-dependent. In contrast to some previous research, chewing gum failed to improve memory. Further research is now required to increase our knowledge of the behavioral effects of chewing gum and to identify the underlying mechanisms.


Psychol Rep. 2009 Oct;105(2):372-4.
Chewing gum and concentration performance.
Tänzer U, von Fintel A, Eikermann T.
University of Oldenburg, Therapy Centre Hamburg-Fuhlsbüttel, Germany. uwe.taenzer@uni-oldenburg.de
Abstract
The effect of chewing gum on performance was examined. Four Grade 3 (8- to 9-year-olds) classes in a German primary school participated; 2 class-es chewed gum during a 16-min. concentration test. Chewing gum had a significant and positive effect on concentration performance.