Sensory Systems Psychology 372 Physiological Psychology Steven E

Sensory Systems Psychology 372 Physiological Psychology Steven E. Meier, Ph. D. Listen to the audio lecture while viewing these slides or view the video presentations available through Blackboard 1

Psyc 372 – Physiological Psychology Overview • Lots of sensation or sensory systems • Whole fields of Psychology are associated with this area • Examples • • • Visual system Auditory system Tactile system Olfactory and Taste system others 2

Psyc 372 – Physiological Psychology Systems overview • Systems have some type of receptor system • Receptor systems are designed to convert some outside stimulus to a electrical-chemical signal • Is called transduction • The electrical-chemical signal is used by the nervous system 3

Psyc 372 – Physiological Psychology Receptor systems • Usually lack axons • Usually form synapses with dendrites of other sensory neurons • Messages are carried on different pathways to specific areas of the brain • Detect small ranges of energy levels • Visual system: 400 to 700 nm • Auditory system: 20 to 20, 000 Hz 4

Psyc 372 – Physiological Psychology Receptor systems • Some systems are more complicated than others • Visual system versus touch system • Visual system was initially part of brain systems • Has become more specialized and moved • Allows more processing of information • Increases survival. 5

Psyc 372 – Physiological Psychology The Eye 6

Psyc 372 – Physiological Psychology Some structures • Pupil: Is basically a hole • Iris: Is a muscle that controls the size of the hole • Cornea: • Is it clear transparent membrane that covers the pupil and Iris • Focuses approximately 75% of visual information onto the retina • Lens: Focuses the remaining 25% of light onto the fovea of the retina 7

Rods and Cones n Two types of photoreceptors are located within the retina l Rods: 120 million Light sensitive (not color) u Found in periphery of retina u Low activation threshold u l Cones: 6 million Are color sensitive u Found mostly in fovea u Source: http: //insight. med. utah. edu/Webvision /imageswv/rodco. EM. jpeg 6. 8 Copyright 2001 by Allyn & Bacon

Retinal Circuitry Adapted from Dowling, J. E. , and Boycott, B. B. Proceedings of the Royal Society of London, B. , 1966, 166, 80 -111. Copyright 2001 by Allyn & Bacon 6. 9

Primary Visual Pathway n Information from each visual field crosses over at the optic chiasm and projects to the opposite side of the primary visual cortex 6. 10 Copyright 2001 by Allyn & Bacon

Visual Cortex 6. 11 Copyright 2001 by Allyn & Bacon

Summary of Visual Cortex n V 4: responds to color (and form perception) u Lesions of V 4 impair color perception V 5: responds to movement n TEO: involved in color discrimination, 2 -d pattern discrimination n u. TEO n projects to area TE TE: neurons here respond to 3 -d objects (a face or a hand) 6. 12 Copyright 2001 by Allyn & Bacon

Psyc 372 – Physiological Psychology Auditory system • Is less sophisticated than the visual system • Designed to transduce frequencies of sound into hearing 13

Psyc 372 – Physiological Psychology Divisions of the • Outer ear: • Channel to tympanic membrane • Middle ear: • Ossicles • Inner ear: • Cochlea Ear

Psyc 372 – Physiological Psychology The Cochlea • The cochlea is formed from three chambers: • Hair cells within the organ of Corti transduce sound waves into nerve impulses 7. 15

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Psyc 372 – Physiological Psychology Auditory Pathways • Afferent pathways: • Through cochlear nuclei • • To To superior olivary nuclei inferior colliculus medial geniculate auditory cortex • Efferent pathway: • Olivocochlear bundle 7. 17

Psyc 372 – Physiological Psychology Touch / Pain • Three different sensations are reported to the brain by receptors localized within skin 7. 18

Psyc 372 – Physiological Psychology Temperature • Is detected by warmth and cold receptors • Receptor activation is relative to the baseline temperature • The receptors lie at different levels of the skin (cold are close to the surface of the skin) 19

Psyc 372 – Physiological Psychology Touch and Pain • Touch involves perception of pressure and vibration of an object on the skin • Pacinian corpuscles detect deformation of the skin • Pain is associated with skin tissue damage • Nociceptors detect pain 20

Psyc 372 – Physiological Psychology Morphology of Skin Epidermis Dermis 7. 21

Psyc 372 – Physiological Psychology Somatosensory Pathways • The dorsal columns carry precise information related to touch • The spinothalamic tract carries pain and temperature signals (poorly localized) • 5 -10 cortical maps of the body surface 7. 22

Psyc 372 – Physiological Psychology Other systems • Taste • Vestibular 23

Psyc 372 – Physiological Psychology Conclusions • Lots of systems • Each has a specific purpose • When damage occurs, usually multiple systems are impacted. • Creates specific symptomatology • Can be used to identify locations of brain or system damage 24