Behavioral Neuroscience, lecture on Turtle Efferent Eyeblink Pathway
USD Department of Biology
Behavioral Neuroscience
C. picta Turtle Eyeblink Behavior
Sensory Stimulation of Eyeblink
Eyeblink Motor Output
Neuromuscular Function
In vitro Conditioning
text:Kandel pages 1243 & 849
Turtles and Ecology
Eyeblink Circuitry
end     Acronyms/Abbreviations
Eyeblink Conditioning
V.  Acetylcholine (ACh)
		        I I
	A. substrates: choline and acetyl CoA
	              (diet)     (Glycolysis and Kreb's)
		1. synthetic enzyme: choline acetyltransferase (CAT)

			a. cytosolic   (most is synaptic)

			b. CoA left over

		2. degradative enzyme: acetylcholine esterase (AChE)

			a. membrane protein

			b. catabolites = choline and acetate
				i. reuptake of choline

			c. turnover = 150ms	or	5,000 ACh molecules/s

	B. Muscarinic and Nicotinic Receptors 	(membrane proteins)

		1. muscarinic M1 - M5    7tm

			a. slow response time (100 - 250 ms)

			b. act directly on ion channels 	

				i. open or close K+, Ca++, or Cl- channels

					(1) may lead to depolarization 
					   or hyperpolarization

			c. and activate 2nd messenger system (via G proteins)
				i. M1,3,5 Gp(q)асPLCасIP3 & Ca++

				ii. M2,4 GiатACатcAMP ат PKA 

		2. Nicotinic

			a. four glycosylated peptide chains a, b, g, d in muscle
			b. neuronal only a & b

			c. ACh binds to the a subunit

				i. binding causes conformational change

					(1) allows cations, not anions, to pass

					(2) Ca++ passing stimulates muscular contraction
					     of pyramidalis, lateral rectus, retractor bulbi
						 causing blinking of nictitating membrane
	C. Central ACh Distribution in vertebrates: Involved in Learning
		1. ACh is produced in the nucleus basalis 

			a. projections to the cerebral cortex and many parts of the brain

			b. these cells degenerate during Alzheimer's disease

		2. ACh is in 2 specific populations in the limbic system

			a. septum to hippocampus  & habenulo-endopeduncular projections

			b. short axon striatal cells
	D. Autonomic NS
		1. all sympathetic and parasympathetic preganglionic neurons

		2. parasympathetic postganglionic neurons
	E. ACh as a transmitter for motor actions and coordination
		1. motor neurons 
	\ all skeletal neuromuscular junctions
			a. Invertebrate motor neurons
			b. Vertebrates motoneurons of the spinal cord and cranial nerves
				i. abducens innervation of 
		2. Cells in the caudate-putamen nucleus involved in motor coordination 
		3. PPT and LPT innervation of substantia nigra

VI. Neuromuscular Function