774 



HANDBOOK OF PHYSIOLOGY 



NEUROPH\'S10L00Y I 



perception 



reticular formation and, 736 



pricking, 472 

 threshold, 462 



quantitation, 463 



reaction, 496 



reaction time to, 473 



receptors, 465-467 



referred, 499-502 



injury to central paths and, 501 

 summation, 500 



reflexes 



lesions inhibiting, 464 



related to itching, 498 



related to tickling, 498 



remembered after inesencephalic stim- 

 ulation, 490 



representation in cerebral hemispheres, 



493 



second response to, 47 1 



significance to individual, 460 



somatic and visceral receptors, 467 



sympathetic nerves and, 480 



tissue damage and, 461 

 Pain, conduction; see Pain fibers, con- 

 duction 

 Pain fibers 



association with temperature fibers, 484 



conduction, 472 

 diameter and, 469 

 ischemia and, 469 



in anterolateral column, 486 



in anterior roots, 479 



in cerebral hemispheres, 492 



in medulla oblongata, 487 



in mesencephalon, 488 



in posterior roots, 479 



in second sensory area, 495 



in spinal cord, 483 



in thalamus, 490, 491 



insulation and, 477 



myelinated and unmyelinated, 485 



specificity for pain, 461 

 Pain threshold 



constancy, 462 



electrical stimulation, 462 



nerve nets and, 476 



thermal radiation and, 461 

 Parasympathetic nervous system 



cholinergic transmission in, 230-233 



pain and, 483 

 Parasympathin 



see also Cholinergic transmitter 



role in cholinergic transmission, 233 

 Partial epilepsy: see Epilepsies, partial 

 Pattern recognition: see Vision 

 Pelecypods 



see also Invertebrates 



ocelli structure in, 630 

 Penis 



warmth receptors in, 444 



Pentylenetetrazol 



pharmacological efTects on synapse, 1 75 

 Pentylenetetrazol seizures 



see also Convulsions generalized. Strych- 

 nine convulsions j Epilepsy; Anoxia, 

 convulsions 

 anoxic convulsions and, 340 

 cortical reactivity, 340 

 grand mal epilepsy and, 341 

 strychnine convulsions and, 340 

 Pericorpuscular synaptic knobs : see Sy- 

 napse, pericorpuscular knobs 

 Perilymph 



composition, 574 

 Peripheral receptive fields: see Sensory 



systems 

 Petit mal epilepsy: we Epilepsies, petit 



mal 

 Pfliiger's law of contraction: see Historical 



development 

 Phasic receptors 

 excitation of, 1 29 

 summation, 130 

 Phoria : see Accommodation 

 Photosensitivity 

 efficiency of, 622 

 in ganglia, 624 



in multicellular organisms. 624 

 in unicellular organisms, 623 

 peripheral, 624 

 Pia-ventricular potential: see DC. po- 

 tentials 

 Picrotoxin 



synaptic transmission and, 1 78 

 Piriform cortex: see Cerebral cortex 

 Pitch: see Frequency discrimination 

 Polarization 



see also Depolarization; Postsynaptic 



potentials 

 d.c. potentials and, 316, 327 

 Polarized light : see Arthropods 

 Postcentral cortex : see First somatic cor- 

 tical field 

 Postdischarges : see Epilepsy 

 Posterior nuclear thalamic group : see 



Thalamus, posterior nuclei 

 Postexcitatory depression 

 definition, 309 

 factor affecting, 309 

 Postsynaptic membrane: see Synapse, 



postsynaptic membrane 

 Postsynaptic potentials, 65-71, 150-190 

 anatomical considerations, 302 

 anoxia and, 302 

 changes in amplitudes, 189 

 character and nature of transmitter, 



166 

 definition, 149 

 depolarizing, 1 73 



central excitatory state and, 164 

 hyperpolarization and, 189 



properties of, 151 



spatial considerations, 182 



during depolarizing, 158 



electrical stimulation and, 153 



excitatory, 65, 152 



factors effecting, 167 



generation site, 150 



genesis of, 1 66 



gradation of, 167 



hyperpolarizing, 151, 158 

 central inhibitory state, 164 

 depolarization and, 189 

 spatial considerations, 182 



hypothermia and, 302 



inhibitory, 69, 152 



interrelation with spikes, 152, 170 



mechanical pressure and, 302 



mode of spread, 165 



nature, 150 



pyramidal neurons and, 303 



reversal of, 1 60 



species differences in, 171 



standing 



electrotonic effects, i8g 

 nonpropagated, 164 



transfer to electrically excitable mem- 

 brane, 168 



trauma, 302 



types of, 151, 172 

 Postural reflexes 



role of utricle in, 557 



vestibular mechanism and, 560 

 Potassium 



conductance, 62, 118 



excitation and, 62-65, '''^' ''9 

 Potassium potential 



resting potential and, 168 

 Potassium theory 



evidence against, 118 



resting potential and, 1 1 7 

 Prepotential 



definition, 304 

 Presynaptic impulse 



effects on postsynaptic region, 1 63 

 Presynaptic membrane: see Synapse, pre- 

 synaptic membrane 

 Presynaptic potential 



anatomical considerations, 302 



anoxia and, 302 



definition, 149 



hypothermia and, 302 



latency, 162 



mechanical pressure and, 302 



trauma and, 302 

 Primary line of sight 



definition, 653 

 Primary receiving area: see First somatic 



cortical field 

 Proprioceptive: see Kinesthetic 

 Protopathic system 



criticism of, 475 



sensory mechanism, 391 



