Behavioral Neuroscience Summers

Aplysia Behavior Fundamentals of Neurocircuitry Sensory Stimulation of Siphon Withdrawl Motor Output driving Siphon Withdrawal Gating Conditioning & Memory

text:Kandel pages 1248-1257 Glutamate (Glu) Acetylcholine (ACh) 5-HT Aplysia and Siphon Withdrawl Siphon Withdrawl Circuitry end     Acronyms/Abbreviations     Syllabus

Siphon Withdrawal
IV. Sensory Stimulation of Siphon Withdrawal 			

	A. Siphon-gill withdrawal reflex Sensory neurons
	
		1. Cell bodies in abdominal ganglion
		
			a. 24
			
		2. mechanoreceptors in the siphon
		
			a. touch causes distension of receptor membrane
			
				i. stretch receptors
				
				ii. opens Na+ channels
				
					(1) leads to depolarization and action potential
		
		3. axon terminals in abdominal ganglion
		
			a. excitatory
			
				i. Neurotransmitter = Glutamate (Glu)
				
				ii. Glu binds AMPA receptors
				
					(1) often paired with NMDA receptors
			
			b. monosynaptic
			
				i. on 13 motor neurons
				
					(1) projecting to muscles in
					    gill or siphon
			
			c. also terminals on interneurons (i.e. disynaptic)
				
				i. excitatory - may be Glu 
				
				ii. inhibitory - may be GABA 
				
				iii. modulatory - serotonin (5-hydroxytryptamine, 5-HT)
	
				
	B. Tail-siphon reflex seonsory neurons
	
		1. Somata in left & right pleural ganglia
		
			a. 200 neurons, bilaterally symmetrical
		
		2. mechanoreceptors in tail
		
		3. monosynaptic excitatory Glu-AMPA terminals
		
			a. on 3 motor neurons
			
				i. in adjacent ipsilateral pedal ganglia
				
					(1) left pleural to left pedal
					
				ii. project to muscles in the tail
			
		4. excitatory and inhibitory interneurons
		
			a. activate motor neurons in the abdominal ganglion
			
				i. project to muscles on siphon
			
			b. and pedal ganglia