Behavioral Neuroscience Summers

Syllabus Yawning Behavior Evolution of Yawning Sensory Afferents to Yawn Gating the Yawn

Regulating Yawn Gating Efferent Yawn Output Neuromuscular Production of Yawns Integration of Yawn Circuitry and Behavior

norepinephrine (NE) Oxytocin (OT) ACTH & aMSH Yawning figures Yawn Circuitry end     Acronyms/Abbreviations

YAWNING

X. Yawning Efferent Motor output 

	A.  Three sets of motor signals must be instigated

		1. in rapid sequence

		2. to initiate yawning

	B. Inhibition of the Swallowing Reflex

		1. blocking contraction must happen before

			a. promoting pharyngeal dilation

	C. Stimulation of Pharyngeal Dilation

		1. Opening stage in the Initiation Phase of Yawning

	D. Inhalation

		2. First stage of the Acme Phase

	E. the rest of Yawning follows

		1.  eyes close

		2. in the morning includes stretching

			a. pandiculation

		3. exhalation is last

			a. Conclusion phase


	F. Inhibition of Swallowing

		1. Blocking contraction

			a. superior, middle, and inferior pharyngeal constrictor muscles

				i. external circular layer of pharynx

				ii. move food toward the esophagus

					a. stripping action of pharyngeal constrictors
					   + plunger action of tongue

			b. stylopharyngus and salpingopharyngus muscles

				i. internal longitudinal layer of the pharynx

		2. Neural inhibitory discharge is normal between swallows

		3. Inhibition of nucleus ambiguous swallowing center

			a. NST GABA Þò NST Glu  Þ nucleus ambiguous

	G. Expansion = Dilation of Pharynx

		1. contraction of genioglossus, geniohyoid, sternothyroid 

			a. pharyngeal dialator muscles

		2. NST  Þ Glu Þñ C8-T2 sympathetic ciliospinal center

			a. ñ AMPA/NMDAC8-T2 sympathetic preganglionic neurons Þñ ACh

			b. ñ ACh Þñ Nicotinic-R SCG sympathetic postganlionic neurons

				i. superior cervical gangion 
            
			c. Þ through the hypoglossal nerve Þñ NE Þ geniohyoid muscle

				i. but how does it cause this muscle to contract?

					1) striatal muscle needs ACh Þñ Nicotinic-R

			d. Þñ NE presynaptically Þñ a1 & b2 receptors Þñ ACh release?

				i. from hypoglossal motor neurons Þñ Nicotinic-R 

				ii. Nicotinic-R Þñ geniohyoid contraction 

					1) Þñ pharyngeal widening

			e. or directly?: 

				i. Þñ NE Þñ geniohyoid a1-R Þñ Gp/PLC/IP3/Ca++

				i. Ca++ Þ troponin Þñ myosin binds actin Þñ geniohyoid contraction
                

	H. Inspiration follows Pharyngeal Dilation

		1. sensory feedback

			a. pharyngeal stretch Þñ NST?

		2. NST GluÞñ AMPA/NMDAC3-5 spinal cord motor neurons Þ phrenic nerve

			a.  motor neurons Þ phrenic nerve Þ end plate terminal ACh  Þ 

			b. ACh Þñ Nicotinic-R diaphragm contraction

				i. downward movement

		3. NST GluÞñ AMPA/NMDAT2-7 spinal cord motor neurons

			a. Þ intercostal nerves  Þ end plate terminal ACh  Þ

			b. ACh Þñ Nicotinic-R intercostal muscles contraction

				i. intercostal contraction Þñ rib cage expansion

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XI. Neuromuscular Production of Yawns
XII. Integration of Yawn Circuitry and Behavior

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