Behavioral Neuroscience, Integrative lecture on Jamming Avoidance Response
USD Department of Biology
Behavioral Neuroscience
Summers
Electric Fish and JAR Behavior
Afferent Path of Electroreception
Control of Electric Organ Discharge
Efferent Output producing EOD
Jamming Avoidance Response
Electric field Glutamate
GABA
Acetylcholine
Electric Fish Figures
Electric Fish Circuitry
Acronyms/Abbreviations    end
Jamming
VII. Jamming Avoidance Response  			 

	A. Two weakly electric fish meet at night in a dimly lit, murky stream
	
		1. each Eigenmannia virescens has a fixed EOD frequency
		
			a. e.g. Ev1 frequency = first fish Glass Knifefish
			
				i. Ev2 frequency = 2nd fish
		
		2. the frequencies are similar
		
			a. but slightly different
			
			b. higher amplitude and frequency at night
	
	B. The combined signal from the 2 Knifefish are additive
	
		1. constructively
		
			a. where the EOD phase is reinforced
			
			b. i.e. Ev1 acrophase overlaps with Ev2 acrophase
			
				i. nadir with nadir 
		
		2. destructively
		
			a.  where EOD is out of phase
			
				i. Ev1 acrophase matches Ev2 nadir
				
					(1) antiphase interference
				
				ii. beat minimum
				
		3. Two signals summate - producing a beating waveform
		
			a. peak-to-trough amplitude fluctuates over time
			
				i. rate = frequency difference Ev1:Ev2 EODs
			
			b. slow Ds from beat frequency
			
				i. 'mask' minor frequency Ds
				
					(1) relative motion between Ev1 and enviroment
					
					(2) impair electrolocation
			 
	C. Ev1 Tuberous (T) receptors  dELL  dTS  nEb 
	     Ev1 Ampullary (P) receptors  vELL 
		
		1. detect the concurrent modulations of signal amplitude and timing
	
			a. Electroreceptor array is spread across the body 
			
				i. skin has a low electrical resistance
			
			b. in body surface regions that detect foreign EODs
		
				i. compare to signals sensed by a reference area
			
					(1) part of the body surface minimally affected
					    by the foreign signal
		
		2. Ev1 tuberous-R  ELL  dTS
		
			a. comparison of reference areas possible due to somatotopic TS
			
				i. feedback from TS  NP  EGp  ELL  TS
			
			b. convergence of Ded frequency signal with 
			
		3. Ev1 ampullary-R  ELL  dTS
		
			a. Ded amplitude signals
			
		4. weakly electric fish can detect a 100 ns time difference
		
			a. 100 billionths of a second (nanoseconds)
			
			b. example: Ev1 is a bigger fish
			
				i. Ev1 > Ev2 amplitude
				
				ii. Ev1 < Ev2 frequency
				
					(1) Ev1 has longer duration EOD signal
			
			c. Ev1+Ev2 combined signal delayed as amplitude 
			
				i. compared to Ev1 EOD
				
				ii. advanced as amplitude 

	D. Ev1 Tuberous-R Glu  AMPA/NMDA:ELL  Glu  AMPA/NMDA:vTS  Glu 
		    Ampullary-R Glu  AMPA/NMDA:ELL  Glu 
		 Mechanosensory-R Glu  AMPA/NMDA:ELL  Glu 

		1.  AMPA/NMDA:nE  GABA
		
		2. GABAA:SPPn  Glu  X NMDA  relay cell firing rate

			a.  EMN firing  EO discharge  frequency EOD

		3. Ev1 P + T  ELL  dTS  Glu  AMPA/NMDA:nEb beat frequency
	
	E. Ev2 P + T receptors  ELL  dTS  nE  Glu 

		1.  AMPA/NMDA:PPnG  Glu  AMPA:Pn pacemaker cells:relay cells 

		2. relay Glu  AMPA/NMDA:EMN  ACh  Nicotinic-R:electrocyte stack 

		3.  discharge frequency   EOD frequency

	
	F. Ev1 is a bigger male
	
		1. must establish dominance hierarchy
		
			a. based on the EOD frequencies of conspecifics
			
				i. extrapolating from work on Brachyhypopomus pinnicaudatus
				
					(1) weakly electric fish with biphasic EOD
					
					(2) electrocytes have 2 active membranes
		
		2. Amplitude and duration of EOD waveform  at night
		
			a. circadian rhythm
			
				i. enhanced by 5-HT 5-HT1A
				
					(1) inhibited by 5-HT2A/C
				
			b. via the Stress system (HPI axis)
		
		3. Stress: mRaph  5-HT  5-HT1A:Hypothalamus CRF  Pituitary 
		        ACTH (+ aMSH) 

			a. ACTH binds MC2-R  Interrenal gland  F (cortisol) 
		
			b. 5-HT + CRF   EOD via the HPI
			
			c. ACTH + aMSH directly stimulate electrocytes
			
				i. altering membrane biophysics
				
				ii. altering discharge waveforms of electrocytes
		
		4. Breeding season  
		
			a. Evf1 EOD > 2X Ev1 EOD frequency
			
			b. HPG T  long duration masculine EODs 
			
				i. shorter duration feminine EODs
			
				ii. Ding kinetics of constituent ionic currents of EOD over days
				
			c. Ev1  EOD frequency
			   to non-breeding Evf2
	
			d. Ev1  EOD frequency
			   to breeding Evf1
			   
		5. Social encounters between Ev1 and Ev2 or Ev1 and Evf1 are stressful

			a. social encounters: aggression and courtship
			
				i. any stimulus  or  EOD involves HPI 
				
					(1) regulate shape of the electric waveform
					
					(2) and energy available for adaptive social response
			
			b. ACTH + aMSH bind MC5-R on electrocytes  cAMP/ PKA
			
				i. 
				
					(1)  Na+ current
					
						(a)  K+ current: inexcitable membrane
					
					(2) in circadian or social Ds
				
				ii. MC5-R also found in striatal muscle
				
					(1) upregulates fatty acid oxidation
					
					(2) neurotrophic at neuromuscular junction
					
					(3) ACh release 
					
					(4)  motor endplate excitability
					
					(5)   muscular AP

			c. dominant males  amplitude + duration EOD
			   have  object detection and electrolocation

				i. also higher energetics
				
					(1)  chance of predation
				
				ii. \ return to fixed normal frequency post-interactions
				
	G. Dominant Ev1 Tuberous-R  ELL  vTS   
	                       Ampullary-R  ELL 
		          Mechanosensory-R  ELL 

		1.  nE  GABA
		
		2. GABAA:SPPn  Glu  X NMDA  relay cell firing rate

			a.  EMN firing  EO discharge  frequency EOD

			b.  recruitment of EMN to be fired  EOD amplitude
			
			c. short-term ACTH  aMSH  MC5

				i. mid-term testosterone/11KT  AR

Syllabus