Abstract
Chewing affects cognitive processes, but the mechanisms are unknown. We used functional magnetic resonance imaging (fMRI) to examine the relationship between chewing and neuronal activity in the human brain, including the hippocampus and prefrontal cortex.
Subjects (n=1188, young-adults [mean age : 25.7±5.9 years] 58 men, 73 women; aged adults [mean age 70.3±3.1 years] 421 men, 636 women) performed an encoding test followed by a recall test of 64 photographs (32 photographs used in the encoding test and 32 new photographs). Subjects judged whether they had previously seen each photograph. BOLD (fMRI) signals in the hippocampus and prefrontal cortex were evaluated in some of the young (mean age 26.1±6.3; 15 men, 9 women) and aged (mean age 71.1±3.3; 11 men, 14 women) adults during picture encoding. Subjects chewed gum for 2 min between the encoding and recall tests.
Memory recall was significantly reduced in aged subjects, but gum chewing increased memory recall by 20%. In young and aged adults, chewing significantly increased fMRI signal intensity in the hippocampus (225%) and prefrontal cortex (240%) and increased the activated brain volume during picture encoding. Chewing enhanced memory recall and activated the hippocampus and prefrontal cortex.
