FOR EACH SENSORY SYSTEM transduction process?webs.wofford.edu/steinmetzkr/Teaching/Psy230PDFs/Senses.pdf · 10/8/12 1 OTHER SENSES Biological Psychology Dr. Steinmetz 1 FOR EACH SENSORY

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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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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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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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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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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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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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Documents

FOR EACH SENSORY SYSTEM transduction process?webs.wofford.edu/steinmetzkr/Teaching/Psy230PDFs/Senses.pdf · 10/8/12 1 OTHER SENSES Biological Psychology Dr. Steinmetz 1 FOR EACH SENSORY