INDEX 



773 



Neurotransmitters: see Transmitter sub- 

 stances 

 Nicotinamide 



visual excitation and, 691 

 Night blindness 



opsins and, 688 



vitamin A and, 688 

 Night myopia : see Myopia 

 Nodal membrane: see Nodes of Ranvier, 



membrane 

 Nodes of Ranvier 



membrane 



threshold stimulation and, 96 



role in conduction, 109 



threshold at, 87 

 Non-photic receptors 



in invertebrates, 369 

 Nonpolarizing competitive inhibitors: see 



Synaptic inactivators 

 Noradrenaline: see Norepinephrine 

 Norepinephrine 



see also Adrenergic transmitter; Epi- 

 nephrine ; Isopropylnorepinephrine ; 

 Dopamine; Transmitter substances; 

 Catechol amines 



acetylcholine and, 210 



as transmitter substance, 218 



characterization, 1 78 



content in autonomic nerves, 220 



differentiation from epinephrine, 218 



other adrenergic transmitters and, 228 



release, 222 



storage, 221 

 Nystagmus 



characteristics of, 558 



reticular formation and, 559 



vestibular mechanism and, 558 



Occipital cortex : see Visual cortex 

 Occlusion 



of evoked potential 



as distinct from inhibition, 310 

 definition, 310 

 Ocelli 



classification, 630 



definition, 628 



insect 



retina in, 631 

 Ocular muscles 



action of vestibular mechanism on, 559 

 Odor measurement 



methods, 539 

 Odorous substances 



characteristics of, 538 



chemical elements and, 538 

 Olfaction, 535-548 



behavior and, 547 



eflferent control of receptors for, 745 



enzyme theories, 539 



olfactory mucosa and, 535 



radiation theories, 539 



receptors for, 535 



species specialization in, 374, 376 



stimulus intensity and response, 536 

 Olfactory bulb 



anesthesia and, 541, 542 



awakening reaction of, 54 1 



central connections, 543 



central control, 745 



efferent pathways, 543 



electrical activity in, 540 



evoked potentials from, 545 



inhibitory efferent fibers, 745 



olfactory mucosa and, 537 



organization of, 537 



patterns of activity in, 540 



removal of, 544 



spatial sumnnation in, 537 



spike discharge from, 544 



spike potentials from, 545 



spontaneous activity, 540 

 Olfactory cortex, 543-547 



electrophysiological investigation, 545 



primary aiea, 544 



relation to rhinencephalon, 546 

 Olfactory mechanisms 



behavior studies and, 547 

 Olfactory mucosa 



alkaline phosphatase in, 539 



arrangement of, 535 



connections with olfactory bulb, 537 



smell sense, 535 

 Olfactory receptors 



anatomy of, 535 



degeneration after olfactory bulb re- 

 moval, 536 



differentiation of response, 542 



innervation, 572 

 Olfactory response, 366 



area differentiation, 542 



temporal differentiation, 543 

 Ommantidia: see Eye, compound 

 Opsin 



see also Visual pigments 



in visual excitation, 679 



night blindness and, 688 



reaction with free sulfhydryl, 680 

 Optic cortex: see Visual cortex 

 Optic nerve 



central control, 745 



discharge 



retinal-initiated, 714 



electrical stimulation, 714 



fiber 



activity of, 617 



spatial summation in, 723 



stimulation 



cortical areas responding, 725 

 geniculate response to, 724 



temporal summation in, 723 

 Optic pathway 



anatomy of, 716 



direct and indirect stimulation, 721 



interaction of elements in, 723 



phenomena in, 716 



radiation 



cortex and, 723 



spatial summation in, 723 



temporal summation in, 723 

 Optics, physiological, 647-691 

 Organ of Corti 



movements, 572 



structure, 571 

 Otoliths 



anatomy of, 551 



gravity stimulation, 557 



stimulation of, 556 



Pacemaker 



artificial and natural, 1 1 7 



definition, 1 16 

 Pain, 459-502 



see also Itching 



abnormal anatomical states and, 475 



abnormal innersation for skin, 467 



adaptation to, 468 



alpha rhythm and, 472 



arterial constriction and, 463 



arterial dilatation and, 463 



asymbolia, 496 



autonomic nervous system and, 480 



burning, 462, 472 



central inhibition of, 499 



chemical excitants of, 478 



corneal stimulus and, 465 



cortical ablation and, 493 



cortical evoked potentials from, 494 



cutaneous 



referred pain and, 501 



definition, 459 



diffuse thalamic projection system and, 



497 

 distention of \'iscera and, 463 

 double response, 47 1 



histological correlates, 473 

 due to cortical or subcortical lesions, 



492 

 due to mechanical stimulation, 467 

 due to thermal stimulation, 467 

 end organs, 465 

 endocrines and, 498 

 experimental subjects for, 464 

 fibers mediating, 468-475 

 frequency of discharge and, 468 

 frontal lobectomy and, 497 

 in second sensory area, 495 

 indifference, 496 

 inflammation and, 463 

 inhibition and, 499 

 ischemia and, 463 

 length of discharge and, 468 

 multiple innervation and, 476 

 parasympathetic nerves and, 483 



