Behavioral Neuroscience Summers

Electric Fish and JAR Behavior Afferent Path of Electroreception Control of Electric Organ Discharge Efferent Output producing EOD Jamming Avoidance Response

Glutamate GABA Acetylcholine Electric Fish Figures Electric Fish Circuitry Acronyms/Abbreviations    end

Jamming
V.vi.  Acetylcholine (ACh)  
                                   O
		        I I
(CH3)3N+-CH2-CH2-O-C-CH3
	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)
							     асDAGасPKC
				i. M1,3,5 Gp(q)асPLCасPIP2асIP3 & Ca++

				ii. M2,4 GiатACатcAMP ат PKA


		2. Nicotinic

			a. made up of 5 subunits, from these a, b, g, d, e
            
				i. four glycosylated peptide chains a, b, g, d in muscle
	
				ii. neuronal only a & b

			
			b. 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 trunk, fin, oculomotor, jaw & opercular 
					     musculature
	
						 
	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. Vertebrate motoneurons of spinal cord & cranial nerves (I-XII)
			
				i. abducens (VI) innervation of the eye
                
				ii. trigeminal (V) innervation of the operculum
			
		2. Cells in the caudate-putamen nucleus involved in motor coordination 
		
		3. PPT (pedunculopontine tegmental nucleus) and LDT (laterodorsal tegmental nucleus)
			innervation of substantia nigra