Behavioral Neuroscience
Yawning Behavior
Evolution of Yawning
Sensory Afferents to Yawn
Gating the Yawn
Yawning Regulating Yawn Gating
Efferent Yawn Output
Neuromuscular Production of Yawns
Integration of Yawn Circuitry and Behavior
norepinephrine (NE)
Oxytocin (OT)
Yawning figures
Yawn Circuitry
end     Acronyms/Abbreviations

XII. Integration of Yawn Circuitry and Behavior A. Basic Linear Circit: Input Þ Output 1. Sensory Inputs a. Eyes-RGCs-Glu Þ RHT Þ SCN core b. SCN core ó SCN shell c. SCN shell Þ AVP Þñ V1A PVN
2. Modulation / Gating Nuclei a. AVP Þñ V1A PVN Þñ OT b. PVN Þñ OT Þñ OT-R NST
3. Efferent Outputs a. NST Þñ Glu Þñ AMPA/NMDA CCC8-T2 i. CCC8-T2 = Ciliospinal Center in C8-T2 spinal cord ii. CCC8-T2 = sympathetic NS preganlionic cell bodies b. CCC8-T2 Þñ ACh Þñ Nicotinic-R SCGÞ hypoglossal nerve i. SCG = Superior Cervical Ganglion ii. SCG = sympathetic NS postganlionic cell bodies iii. hypoglossal nerve contains some postganlionic axons c. SCG Þñ NE Þñ a1-Gp/Ca++ & b2-Gs/cAMP Þñ ACh release i. ACh released from geniohyoid motor neuron 1) presynaptic sympathetic stimulation ii. also housed in C8-T2 spinal cord iii. delivered in parallel via the hypoglossal nerve d. ñ ACh Þñ Nicotinic-R Þñ geniohyoid contraction i. also genioglossus and sterothyroid contraction ii. pharynx expansion Þñ 1st stage of initial yawn phase
B. Enhancing Modulation at Gating Nuclei 1. Self-reinforcing OT potentiation a. PVN OT secreted Þ i. OT-Rs in brainstem 1) NST (output) 2) VTA (DA) 3) LC (NE) ii. OT-Rs in limbic system 1) vSubiculum 2) pMeA b. Þñ OT-R vSubiculum Þñ Glu release i. Þñ OT-R pMeA Þñ Glu release ii. Þñ Glu Þñ AMPA/NMDA VTA c. Þñ OT-R VTA Þñ DA release i. Þñ AMPA/NMDA VTA Þñ DA release ii. Þñ DA Þñ D1 PVN 1) Þñ D1 PVN Þñ OT 2. enhanced ACTH & aMSH potentiation a. Þñ OT-R LC Þñ NE release i. Þñ NE Þñ a1-R ARC Þñ aMSH release 1) aMSH Þñ MC4 PVN Þñ OT b. SCN Þñ AVP & VIP release i. AVP Þñ V1A ARC Þñ ACTH PVN ii. VIP Þñ VPAC1 ARC Þñ ACTH & aMSH PVN 1) ACTH Þñ MC4 PVN Þñ OT
C. Alternative Motor outputs 1.Þñ NE Þñ geniohyoid a1-R Þñ Gp/PLC/IP3/Ca++ 2. Ca++ Þ troponin Þñ myosin binds actin Þñ geniohyoid contraction
D. Inspiration follows Pharyngeal Dilation 1. sensory feedback a. pharyngeal stretch Þñ NST 2. NST GluÞ AMPA/NMDAC3-5 spinal cord motor neurons Þ phrenic nerve a. motor neurons Þ phrenic nerve Þ end plate terminal ACh Þ b. ACh Þ 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 Þ rib cage expansion
E. Acme phase also includes 1. thorax reaches maximum capacity a. followed by a brief interruption of inspiration 2. eyes close 3. limb stretching a. yawning + stretching = Pandiculation b. generalized stretching of respiratory tract muscles i. diaphragm, intercostals, face and neck F. Conclusion phase: short expiration and relaxation

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