Figure 2.

Definitions of feeding sequence, gape cycle and gape cycle phases. The red line shows open-close motor displacements (gape) of the lower jaw during a complete feeding sequence from ingestion to final swallow. The second derivative of the displacement, the blue line, is used to define the four chew cycle phases. Most chewing gape cycles are made up of Hiiemae’s four gape cycle phases: fast close, FC; slow close, SC; slow open, SO; fast open, FO (Hiiemae and Crompton 1985). The four gape cycle phases are delineated by jaw and tongue kinematic events associated with changes in sensory afferent input that are key events in sensorimotor control (Lund 1991): SC starts when the teeth contact the food and mandibular closing movements slow; SC ends and SO begins when the mandible stops moving upwards and begins moving downwards (min-gape); SO ends when the mandible starts depressing quickly (SO-FO transition, in theory when tongue has captured the food item ready for transport); and FO ends when the mandible changes from depression to elevation (max-gape).