Table 1.

VFSS metrics and operational definitions.

VFSS metrics		Operational definitions	Units
Drinking	Lick rate	Number of jaw open/close cycles per second, calculated separately for each second of a 2 s video clip, then averaged.	#/s
	Inter-lick interval	Time between successive lick cycles throughout a 2 s video clip.	ms
	Swallow rate	Number of swallows in each second of a 2 s video clip, converted to a rate (swallows/second), then averaged.	#/s
	Inter-swallow interval	Time between successive swallow pairs throughout a 2 s video clip, then averaged.	ms
	Lick-swallow ratio	Number of jaw open/close cycles between each successive swallow pair throughout a 2 s video clip, then averaged.	n/a
	Pharyngeal transit time	Bolus flow time through the pharynx for each successive swallow, then averaged. The start frame is the “rest frame” that immediately precedes visible transfer of the bolus from the vallecula (swallow trigger point). The end frame is when the tail of the bolus enters the esophagus.	ms
	Jaw closing velocity	Speed at which the jaw closes during each jaw cycle throughout a 2 s video clip, then averaged.	mm/s
	Jaw opening velocity	Speed at which the jaw opens during each jaw cycle throughout a 2 s video clip, then averaged.	mm/s
Eating	Mastication rate	Number of jaw open/close cycles per second during three separate 1 s episodes of rotary mastication, then averaged.	#/s
	Swallow rate	Number of swallows in each second of a 20 s video clip, converted to a rate (swallows/second), then averaged.	#/s
	Inter-swallow interval	Time between successive swallow pairs throughout a 20 s video clip, then averaged.	s

All video clips depict uninterrupted drinking or eating behaviors, beginning with a swallow event (i.e., rest frame immediately preceding bolus flow from the vallecula). For each mouse, five 2 s episodes of drinking and one 20 s episode of eating were analyzed via JawTrack™.