© Cengage Learning 2016 Nonvisual Sensation and Perception Chapter Seven

© Cengage Learning 2016 Intensity: amplitude of sound wave –Vary from quiet whisper to rock band –Logarithmic scale of intensity (decibels, dB) Frequency: wavelength of a sound wave –Determines pitch –Single frequency = pure tone –Multiple frequencies (timbre vs. noise) –Measured in cycles per second in units of Hertz (Hz) Audition: Sound as a Stimulus

© Cengage Learning 2016 The Auditory World Differs Across Species

© Cengage Learning 2016 Sound Results From the Collision of Molecules

© Cengage Learning 2016 Sounds Vary Along the Dimensions of Amplitude, Frequency, and Complexity

© Cengage Learning 2016 Intensity Levels of Common Sounds

© Cengage Learning 2016 The outer ear –Pinna; auditory canal The middle ear –Tympanic membrane (eardrum) –Ossicles (malleus, incus, stapes) –Oval window The inner ear –Semicircular canal; cochlea The Structure and Function of the Auditory System

© Cengage Learning 2016 The Anatomy of the Ear

© Cengage Learning 2016 Three chambers –Vestibular canal (perilymph) –Tympanic canal (perilymph) –Cochlear duct (endolymph) Organ of Corti (inner and outer hair cells) Separated by membranes –Reissner’s membrane –Basilar membrane: tectorial membrane –Round window The Cochlea

© Cengage Learning 2016 The Cochlea

© Cengage Learning 2016 Sound Frequencies Are Translated by the Basilar Membrane

© Cengage Learning 2016 The Movement of the Cilia Regulates Neurotransmitter Release by Hair Cells

© Cengage Learning 2016 Spiral ganglia neurons communicate with cochlear hair cells and the dorsal and ventral cochlear nuclei of the medulla Cochlear nuclei synapse directly or indirectly with the inferior colliculus The inferior colliculus projects to the medial geniculate nucleus (MGN) of the thalamus Central Auditory Pathways

© Cengage Learning 2016 The MGN projects to the primary auditory cortex Primary auditory cortex –Columns respond to single frequencies Secondary auditory cortex –Activated by complex stimuli –Separate pathways process the “what” and “where” of sound The Auditory Cortex

© Cengage Learning 2016 Auditory Pathways from the Cochlea to the Cortex

© Cengage Learning 2016 Tonotopic Organization is Maintained by the Auditory Cortex

© Cengage Learning 2016 Pitch perception –Tonotopic organization (place theory) –Temporal theory Loudness perception –Decibel level describes physical qualities of sound stimulus –Loudness is the human perception of that stimulus –Equal loudness contours –Decibel range of auditory neurons Auditory Perception

© Cengage Learning 2016 Equal Loudness Contours

© Cengage Learning 2016 Horizontal plane –Comparison of arrival times of sounds at each ear –Differences in intensities between each ear –Binaural neurons Vertical plane –Pinna Localization of Sound

© Cengage Learning 2016 We Localize Sound by Comparing Arrival Times at Both Ears

© Cengage Learning 2016 Age-related hearing loss –Poor circulation to the inner ear; exposure to loud noise Damage to outer or middle ear –Conduction loss due to wax build-up, infection, or otosclerosis –Treated with hearing aids Damage to inner ear, auditory pathways, or auditory cortex –Treated with cochlear prosthetics Hearing Disorders

© Cengage Learning 2016 Cochlear Prosthetics

© Cengage Learning 2016 The somatosensory system provides information related to: –The position and movement of the body –Touch –Skin temperature –Pain The Body Senses

© Cengage Learning 2016 Movement receptors of the inner ear –Otolith organs Utricle and saccule Head position and linear acceleration –Semicircular canals Rotation of the head The Vestibular System

© Cengage Learning 2016 The Vestibular Structures of the Inner Ear

© Cengage Learning 2016 Central pathways –Axons from vestibular organs travel along auditory nerve to the cerebellum and vestibular nucleus –Axons from vestibular nucleus communicate with spinal cord and ventral posterior (VP) nucleus –VP nucleus projects to primary somatosensory cortex and primary motor cortex The Vestibular System

© Cengage Learning 2016 Skin structure –Hairy and glabrous (hairless) skin –Epidermis, dermis, subcutaneous tissue Mechanoreceptors –Encapsulated: Meissner’s and Pacinian corpuscles –Nonencapsulated: Merkel’s disks and Ruffini’s endings –Free nerve endings –Two-point discrimination test Touch

© Cengage Learning 2016 Mechanoreceptors in the Skin

© Cengage Learning 2016 Major Features of the Mechanoreceptors

© Cengage Learning 2016 Two-Point Discrimination Thresholds

© Cengage Learning 2016 The Four Classes of Sensory Axons Differ in Size and Speed

© Cengage Learning 2016 Signals from mechanoreceptors travel from skin along Aβ axons to the dorsal roots of the spinal cord: dermatomes From the spinal cord, axons travel along the dorsal column-medial lemniscal pathway to the dorsal column nuclei of the medulla Touch Pathways

© Cengage Learning 2016 Axons from the dorsal column nuclei cross the midline to the contralateral ventral (VP) posterior nucleus of the thalamus, then project to the primary somatosensory cortex Touch information from the head travels to the VP nucleus via the cranial nerves Touch Pathways (cont’d.)

© Cengage Learning 2016 Dermatomes Are Areas of Skin Served by the Dorsal Roots of One Spinal Nerve

© Cengage Learning 2016 Touch Pathways

© Cengage Learning 2016 Somatosensory Areas of the Thalamus

© Cengage Learning 2016 The Sensory Homunculus

© Cengage Learning 2016 Somatosensory cortex rearranges itself in response to changes in the amount of input it receives –Phantom pain –Referred sensations The Plasticity of Touch

© Cengage Learning 2016 Damage to the primary somatosensory cortex –Sensation and movement deficits Damage to the secondary somatosensory cortex –Neglect syndrome Somatosensory Disorders

© Cengage Learning 2016 A purpose for pain –Emotional, cultural, and experiential components –Relays information about tissue injury Receptors for pain –Nociceptors –Mechanical injury, extreme temperature, and certain chemicals activate nociceptors Pain

© Cengage Learning 2016 Ascending pain fibers –Myelinated Aδ (quick, sharp pain) –Unmyelinated C fibers (dull ache) –Glutamate and substance P Spinal cord to the substantia gelatinosa to the spinothalamic pathway; synapse in the thalamus –Pain signals from head/neck travel along the trigeminal nerve, synapse in the spinal trigeminal nucleus; forms trigeminal lemniscus Ascending Pain Pathways to the Brain

© Cengage Learning 2016 Spinothalamic and trigeminal lemniscus fibers synapse in VP nucleus or intralaminar nuclei of the thalamus Communicate with the anterior cingulate cortex and somatosensory cortex Gate theory of pain –Explains the effect of context on pain perception Ascending Pain Pathways to the Brain (cont’d.)

© Cengage Learning 2016 Ascending Pain Pathways

© Cengage Learning 2016 Higher level brain structures project to the periaqueductal gray (PAG) of the midbrain PAG projects to the raphe nuclei of the medulla and the spinal cord Descending Pain Pathways to the Brain

© Cengage Learning 2016 Descending Messages Influence Pain

© Cengage Learning 2016 Opioid activity Periaqueductal gray (PAG) associated with cultural, emotional, and experiential influences on pain sensation Managing Pain

© Cengage Learning 2016 Sense of smell Detection of airborne molecules Olfactory receptors: bipolar –Line the olfactory epithelium in the dorsal nasal cavity –Olfactory neurons form the olfactory nerve –Molecules dissolve in mucus surrounding olfactory receptors –Depolarization sends action potentials to the olfactory bulb via the olfactory nerve The Chemical Senses: Olfaction

© Cengage Learning 2016 Signals to the olfactory bulb are sorted by glomeruli Olfactory bulb axons form olfactory tracts, project to the olfactory cortex –Does not synapse in thalamus first Olfactory Pathways

© Cengage Learning 2016 Olfactory cortex connects to the medial dorsal nucleus of the thalamus, which projects to the insula and the orbitofrontal cortex Olfactory signals are interpreted as odor identification, motivation, emotion, and memory Olfactory Pathways (cont’d.)

© Cengage Learning 2016 Olfactory Information Travels from the Epithelium to the Brain

© Cengage Learning 2016 Sense of taste –Protection from poisonous or spoiled food –Attraction to foods is necessary for survival Dissolved chemicals in saliva Five major taste classes –Sweet, sour, bitter, salty, umami The Chemical Senses: Gustation

© Cengage Learning 2016 Found on tongue and other areas of the mouth Papilla contain taste buds Taste buds have receptor cells –Receptor cells are not neurons, but can form synapses –Microvilli project into saliva –Transduction mechanisms for chemical stimuli result in depolarization of taste receptor cells Gustatory Receptors

© Cengage Learning 2016 The Taste Receptors

© Cengage Learning 2016 Taste fibers in tongue form parts of cranial nerves VII, IX, and X Cranial nerves synapse with gustatory nucleus of the medulla Gustatory Pathways

© Cengage Learning 2016 Axons from gustatory nucleus synapse in the ventral posterior medial (VPM) nucleus of the thalamus –Projects to the gustatory cortex in the parietal lobe for identification of primary taste qualities –Projects to the orbitofrontal cortex in the frontal lobe for combination with olfaction and vision to produce flavor perceptions Gustatory Pathways (cont’d.)

© Cengage Learning 2016 Gustatory Pathways to the Brain