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OTHER SENSES
Biological Psychology Dr. Steinmetz
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FOR EACH SENSORY SYSTEM
¢ What is the physical stimulus? ¢ What is the receptor/transduction process?
¢ What is the neural pathway?
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LAW OF SPECIFIC NERVE ENERGIES ¢ Each afferent sensory nerve: � transmits information about a particular
stimulus � Receptors à central nervous system
¢ Any activity in that afferent sensory nerve � interpreted by the brain as specific to the
associated type of stimulus
For example: � the optic nerve carries visual information to the brain, if
artificially stimulated you “see” � the auditory nerve carries auditory information to the brain, if
artificially stimulated you “hear”
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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PHYSICAL STIMULUS - AUDITION ¢ Sound waves are periodic compressions of air ¢ 2 important features of sound waves:
1. Wavelength Frequency = pitch Hertz (Hz) = # of cycles / sec The more cycles per second, the higher the pitch or tone.
2. Amplitude = intensity - loudness Vertical size measured in decibels The larger the wave height, the louder the sound.
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RECEPTORS & TRANSDUCTION - AUDITION ¢ Pinna – collects sound used in localization
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RECEPTORS & TRANSDUCTION - AUDITION 8
¢ Middle ear – tympanic membrane receives air wave � bones amplify
the wave � transmit to fluid-
filled cochlea (amplify = air to fluid)
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RECEPTORS & TRANSDUCTION - AUDITION ¢ Inner ear = cochlea has hair cell receptors
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HEARING
Auditory receptors = hair cells
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AUDITORY TRANSDUCTION PROCESS
¢ Tectorial membrane moves with the vibrations of fluid in the cochlea � Movement opens
ion (K+) channels in hair cells (receptors) located in the basilar membrane
� Endolymph (fluid in cochlea) has high concentration K+
K+
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• NT (neurotransmitter) from the hair cells activates action potentials in the auditory nerve
K+
AUDITORY TRANSDUCTION PROCESS
¢ K+ comes into the hair cells making them more positive activating voltage-gated Ca2+ channels
¢ Hair cells release NT
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¢ http://www.youtube.com/watch?NR=1&feature=endscreen&v=0jyxhozq89g
¢ http://www.youtube.com/watch?v=PeTriGTENoc&feature=related
¢ http://www.youtube.com/watch?v=dyenMluFaUw
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Fig. 7-5, p. 194
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CORTICAL AREAS - AUDITORY
¢ Superior Temporal Gyrus, A1 = primary auditory cortex tonotopic organization
• Secondary auditory cortex = complex tone processing, Wernicke’s Area = speech recognition
• Association auditory cortex = combine auditory signals with meaning, Angular Gyrus = speech comprehension
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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PHYSICAL STIMULUS - VESTIBULAR
¢ Vestibular system - responsible for balance, posture, and eye movements
¢ 2 different stimuli and 2 sets of receptors: � head tilt / orientation relative to gravity � acceleration & deceleration (movement)
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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PHYSICAL STIMULUS - GUSTATION & OLFACTION
¢ Olfactory (smell) stimuli are typically chemicals
suspended in the air � Tens of thousands of different olfactory stimuli
¢ Gustatory (taste) stimuli are dissolved chemicals (solution or saliva) � Sweet, Sour, Salty, Bitter, Umami, others?
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RECEPTORS - OLFACTORY ¢ Olfactory receptors are
found in the back of the nasal cavity.
¢ Olfactory receptors are neurons.
¢ Olfactory receptor neurons have cilia suspended in a mucous fluid.
¢ Olfactory 7-TM receptors similar to NT metabotropic receptors.
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NEURAL PATHWAY - OLFACTORY ¢ Olfactory receptors located in
the olfactory mucosa → Olfactory bulb → Olfactory nerve → Amygdala & Thalamus →
¢ Thalamus to Primary Olfactory cortex in the frontal lobe (piriform) & limbic system
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WHY DO SMELLS MAKE US REMEMBER?
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VOMERONASAL ORGAN ¢ Small specialized
component of the olfactory system
¢ Separate system: different receptors & neural pathway
¢ More prominent in non-human mammals
¢ Receives pheromones
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PHEROMONE CHEMICAL STIMULI ¢ Pheromones are chemicals
given off by an animal which have an effect on the behavior of other animals (reproductive or sexual behavior)
¢ Vomeronasal organ (VMO)
¢ Are there human pheromones?
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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RECEPTOR - GUSTATORY
¢ Taste Buds contain taste receptor cells (TRCs)
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Salt = ionotropic Tastant Entry
Sour = ionotropic Ion (K+) Block
Bitter = Metabotropic
Sweet = Metabotropic
Tight Junction
Taste Cell
TRANSDUCTION - GUSTATORY 28
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¢ Taste Receptors
¢ Gustatory Nucleus (medulla)
¢ VPM nucleus of thalamus
¢ Gustatory cortex
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CORTICAL AREAS - GUSTATORY
PBN / Amygdala
¢ Insula & Frontal Operculum = primary taste perception
¢ Orbitofrontal Cortex = flavor
¢ Hypothalamus = hunger and satiety
¢ PBN/Amygdala = emotion (cravings or aversions)
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OUTLINE ¢ Auditory System ¢ Vestibular System ¢ Olfactory System ¢ Gustatory System ¢ Somatosensory System
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PHYSICAL STIMULUS - SOMATOSENSATION
¢ There are many different stimuli: � Touch – pressure & vibration
(movement), � Nociceptors - temperature &
tissue damage (pain) ¢ Each stimulus has at least one
specialized receptor (several have at least 2 receptors)
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RECEPTORS - SOMATOSENSORY 33
SKIN RECEPTORS 34
¢ Pacinian corpuscles – touch, high frequency vibration
¢ Meissner's corpuscles – pressure, low frequency vibration
¢ Merkel's disks - pressure ¢ Ruffini's corpuscles –
stretch, vibration (not pressure)
¢ Free-nerve endings - temperature, pain
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TRANSDUCTION & NEURAL CODING
¢ Touch bends the receptor opening ion channels
¢ Pacinian Corpuscle: pressure onset / offset detector
Action potential output
• The structure of the Pacinian corpuscle makes the receptor selective to onset & offset stimuli and not to constant stimulus
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TOUCH PATHWAY & CORTICAL AREAS
¢ Sensory neurons enter the spinal cord organized by dermatome, form synapses, & then send axons up the dorsal spinal cord
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TOUCH PATHWAY & CORTICAL AREAS
¢ Cross midline at brainstem, synapse at VP thalamus, terminate at contralateral S1, somatosensory cortex (post- central gyrus)
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INCOMING PAIN SIGNALS
¢ Difference between incoming temperature signals and pain signals is the release of substance P as the neurotransmitter for PAIN
¢ Specialized signal for pain that is unique
¢ Pain is a very important signal to recognize & respond to!
Pain input to brain
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PAIN MANAGEMENT PATHWAYS
¢ Periaquaductal Grey & Raphe nuclei send endorphins to reduce incoming pain at spinal cord level
¢ Localized release versus opiate medicines which have global effects
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GATE CONTROL THEORY
Inhibits substance P release
Pain input to brain
Brain output to block pain
PAG & Raphe N.
¢ Signal from the PAG / Raphe N. closes the gate.
¢ Localized release of endorphins at the precise site
¢ Inhibits incoming pain sensations through heteroreceptors!
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TWINS ATTACHED AT THE THALAMUS?
¢ http://www.nytimes.com/2011/05/29/magazine/could-conjoined-twins-share-a-mind.html
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FOR NEXT TIME… ¢ Read Ch. 9: Regulation ¢ EMG Statistical Analysis Olin 212 on Wednesday
¢ Peer Review of Lab Reports due Thursday
¢ Study for Exam 2
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