TEMPORAL DYNAMICS OF HUMAN MASTICATORY SEQUENCES

Many motor behaviors produced by humans and other mammals are temporal ly segmented. That is, sequences of rhythmic or repetitive behavior oc cur as a series of brief, 2- to 4-s bouts separated from each other by pauses or posture adjustments. Little is known about the physiologica l mechanisms underlying temporal segmentation, although several hypoth eses have been advanced. Experimental and modeling studies are current ly underway to gain insight into this phenomenon. One of the problems hampering advancement is the lack of relatively simple behavior models that can be studied in both humans and other mammals. We have recentl y reported that temporal segmentation occurs in guinea pig chewing seq uences. Thus, it seems logical to explore whether temporal segmentatio n occurs in human chewing sequences as well. Toward this end, the curr ent study evaluated the temporal dynamics of chewing sequences in huma ns. Thirteen subjects were videotaped on campus eating areas during lu nch-time. Inter-occlude intervals, i.e., time between maximum jaw clos ures, were calculated using a custom computer program, which also reco rded whether the interval represented a chew or a pause in chewing. Ch ewing rare, pause durations, and chewing burst durations, i.e., durati on of continuous chewing uninterrupted by pauses, were calculated. Med ian chewing burst duration for the sample was 2.91 s. This corroborate s other studies' findings of 3-s temporal segmentation in repetitive m ovements. We conclude that automatic chewing sequences contain tempora l segmentation. Future work is required to gain insight into whether t he physiological mechanisms of this time-based phenomenon are similar among different species. (C) 1998 Elsevier Science Inc.