L4: Neural Control of Swallowing

Question 1

neural control of swallow is…

at a minimum it involves…

but also incorporates…

Answer 1

multidimensional

brainstem “swallow centre” in medulla;

sensory inputs from pharynx, larynx, esophagus;

motor outputs via motor nuclei and motorneurons to muscles

also incorporates descending cortical and subcortical inputs

Question 2

medullary swallow centre is…

Answer 2

a central pattern generator

functional neural circuit = groups of neurons generate motor pattern without reliance on peripheral sensory feedback

bilateral

Question 3

medullary swallow centre has two groups:

Answer 3

dorsal swallowing group

ventral swallowing group

Question 4

dorsal swallowing group involves

Answer 4

nucleus tractus solitarius (NTS) and adjacent reticular formation (RF)

programming component (active early in swallow)

Question 5

ventral swallowing group involves

Answer 5

nucleus ambiguous and adjacent RF

motor execution component (active later in swallow)

Question 6

the dorsal swallowing group receives what inputs?

Answer 6

palatal, pharyngeal, laryngeal

neurons can be excited by electrical stimulation of CN IX and X (phX and iSLN)

Question 7

synapses in the dorsal swallowing group can be ….

also called…

Answer 7

excitatory or inhibtitory

trigger neurons = stimulation results in a swallow

Question 8

describe the initiation of the pharyngeal swallow

Answer 8

most complex ‘reflex’ initiated by CNS

afferent info from IX and phX is necessary to trigger pharyngeal swallow response but also must be sufficient

sensory threshold = affected by level of arousal and by sensory capacity

best when it comes from a larger number of receptive fields, dynamic and multimodal

Question 9

ventral swallowing group: activity of neurons above NA occurs…

Answer 9

during leading phase of swallowing - “motor control”

active following firing in the DSG; damage to DSG neurons eliminates VSG responses

activity of neurons w/i NA - “motor execution”