Behavioral Neuroscience Summers

text:The Basis of Neuropharmacology 8th Edition - Cooper, Bloom, Roth:read 336-338 Rhythmicity & Behavior Sensory input for Rhythmicity Afferent path to the SCN Circadian Rhythms Efferent SCN output Integration of Rhythms into Behavior end     Acronyms/Abbreviations     Syllabus

Glu VIP AVP GABA 5-HT Figures of Rhythmicity Retina-RGC-SCN Molecular SCN

BIOLOGICAL RHYTHMS
II. Sensory input for Rhythmicity 			

	A. Sensory input is necessary for Entrainment of Rhythms

		1. zeitgeibers reset biological clocks through a
		   variety of sensory systems
		   
			a. phase shift free running period

				i. move circadian rhythms from 23 or 28 h to 24 h
				
				ii. match variable onset

				
		2. photoreceptive organs

			a. retina, retinal ganglia

				i. light, greeness, social cues
				
					(1) night sensitivity greatest
					
			b. parietal eye (sharks, frogs, lizards)
				
				i. light, temperature (IR light)

				
			c. photosensitive nuclei - photoreceptive pineal (birds)
			   habenula
			   
			   i. blinded house sparrows still show circadian
			      rhythms
				  
				  	(1) require brighter lights
					
					(2) light passes through skull 
					    and brain tissue
						
							(a) even in humans

			
		3. chemoreceptive organs
		
			a. olfactory - food availability, social cues
			
			b. vomeronasal - social cues
			
			c. gustatory

		
		4. Auditory - sound

		
		5. Tactile

			a. temperature, moisture, water pressure, gravity

					    
			b. activity (proprioception?)

				i. path from Intergeniculate leaflet (IGL) to
				   SCN entrains rhythms

				ii. activates "clock" genes in IGL
				
				iii. IGL neuropeptide Y (NPY) phase shifts SCN

				
			c. food-eating (distention - stretch receptors?)

							
		6. Magnetic

			a. Ampullae of Lorenzini - sharks
			
			b. Magnetite/ferrite in brain
			
				i. nucleus of the basal optic root 

		
	B. Eyes
	
	
		1. Retina
		
			a. neural lining of the eye
			
				i. contains rods and cones
				
				ii. with rhodopsin - photosensitive pigment

		
		2. Retinal Ganglia
		
			a. Rods and Cones are NOT sufficient for entrainment

			
				i. retinal ganglia cells receive signals from 
				   rods and cones
				
					(1) some RGCs innervate the SCN

					
			b. Melanopsin
			
				i. circadian photoreceptor
				
				ii. other photoreceptors: cryptochromes

					
			c. Rods + Cones + Melanopsin together necessary
			
				i. cascade from Glu and PACAP
				
					(1) activate genetic (mPer1+2)
					    cirdadian mechanism
						
				ii. directly to SCN and via IGL