Behavioral Neuroscience, lecture on Honey Bee Proboscis Extension Motor output
USD Department of Biology
Behavioral Neuroscience
Honey Bee Ecology and Behavior
Honey Bee Neuroanatomy
Fundamentals of Neurocircuitry
Sensory Afferent input for Proboscis Extension
Apis mellifera Gating Proboscis Extension
Learning to Drink
Conditioned Proboscis Extenstion
Motor Neuron output for Proboscis Extension
Acetylcholine ACh
Octopamine OA
Integration: Honey Bee Conditioned Drinking
Honey Bee figures
Honey Bee Conditioned Drinking Neurocircuitry
end     Acronyms/Abbreviations
Honey Bee Conditioned Drinking
XIII. Neuromuscular Mechanism for Proboscis Extension  
	A.	MB Pe-1 projects to motor units in the SEG

		1. also project to non-PN neurons in the LH

			a.	Pe-1 + LH pre-motor neurons project to SEG motor neurons

	B.	Motoneurons line the ventral side of the SEG

		1.	Cell bodies in hemiganglia

		2.	Projections extend to several muscle groups

			a.	Abductor of the mandible muscle (M8)

			b.	Adductor of the mandible muscle (M9)

		3. secrete ACh at neuromuscular junctions

	C.	largest muscle in the honey bee’s head region

		1.	Retractor of the labium muscle (M17)

		2.	Retractor of the glossa muscle (M20)

	D.	ACh binds to Nicotinic receptors at a neuromuscular synapse

		1. stimulates action potential (AP = end-plate potential or EPP) 

			a. opening transmitter-gated cation channel = NAChR
				i. Na+ passes first
					1) depolarizes muscle membrane
						a) K+ Ca++ also pass
							i) large diameter channel

		2.	AP moves along sarcolemma and into transverse tubules

			a. sarcoplasmic reticulum
			b. opens voltage gated Ca++ channels

		3. Ca++ binds to troponin

			a. conformational change in tropomyosin
			b. uncovers binding site for myosin on actin
		4. myosin heads binds to actin helical chain	  	   

			a. myosin head conformational change
			b. myosin heads pull actin filamiens across myosin (muscle contracts)

		5. ATP allows unbinding of actin

			a. Ca++ATPase returns Ca++ 
				i. to cisternae of sarcoplasmic reticulum 

	E. Abductor of the mandible (M8) muscle opens mandible
		1. Proboscis extends mechanically
		2. Nectar sampled

			a. chemoreceptors activated

			b. GRN ACh released
			c. nAChR activates VUMmx1

			d. OA binds AmOA1

				i. in LH and MB
			e. sucrose reward reinforced
				i. US paired with CS

			f. NO sucrose reward from CR
	F. Followed by Retractors (M17 & M20)
		1. Proboscis retracts 
	G. Last - mandible adductor closes mandible

XIV. Integration: Honey Bee Conditioned Drinking