SENSORY, MOTOR, AND INTEGRATIVE SYSTEMS

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SENSORY, MOTOR, AND INTEGRATIVE SYSTEMS

• BIOL 242

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• Functions of receiving sensory input
• Integrating, associating and storing information
• Transmitting motor impulses
• Sensation - input may never reach the conscious
  part of the brain
• filtered out and dealt with in discrete areas of
  the brain
• hear a friend's voice
• turn recognize and remember name

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Levels of Sensation

• Sensation - awareness of external or internal
  stimuli - conscious or unconscious
• small differences in intensity - boundaries of an
  object feature extraction
• survival value
• Lower brain - deals with automatically
• Thalamus - general areas of sensation
• Cerebrum - more precise locations
• Perceptions - conscious awareness and
  interpretations of senses
• arrive on sensory (cerebral) cortex
• arrive by divergent pathways
• some may go to various areas - parallel
  processing
• Referred
• served by the same spinal nerves
• Phantom pain

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What is your perception?

• http//www.echalk.co.uk/amusements/OpticalIllusion
  s/colourPerception/colourPerception.html
• http//webvision.med.utah.edu/KallColor.html

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Modality

• specific type of sensation
• temp, pain, touch.....

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Sensory Receptors

• Specific to type of stimuli
• Classification
• Simple - general senses
• touch, pressure, vibration, temp...
• free nerve endings -
• Complex - special senses
• eye, ear, taste, smell, ...

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Sensory Receptors

• Specific Locations
• Exterior/Interior/Proprioceptors
  (position/movement)
• Stimuli Mechano/Thermo/Noci (pain)/Photo/Chemo

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Sensory Receptors

• Potentials - size varies w/stimulus
• Generator potentials ? an AP always
  depolarization
• Receptor potentials ? no AP
• this is for all special senses except olfactory
• may be depolarized or hyperpolarized
• may regulate exocytosis of NTs

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General Senses

• Dermatomes - spinal nerve to restricted region of
  body
• fibers may be classified based upon diameter and
  myelination

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General Senses

• Tactile mechanically sensitive
• Touch - Meissners corpuscles
• in dermis of skin
• fine touch, pressure, low frequency vibrations

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General Senses

• Hair Root Plexuses
• networks around hair follicles

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General Senses

• Merkel Discs
• dendrites to stratum basale
• fine touch

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General Senses

• Organs of Ruffi
• deep in the dermis
• heavy continuous touch

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General Senses

• Pacinian corpuscle - onion CT over a dendrite
• found subQ
• Pressure, pulsing or high frequency
• Vibration
• Itch and Tickle
• itch chemicals on free nerve endings
• tickle - arises from someone else - cant do
  yourself

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General Senses

• Thermal - free nerve endings determine amount of
  heat
• "cold" receptors
• fire from 35--20 C increase firing as go colder
• "hot" receptors
• fire from 30-45C increase firing as go warmer
• Pain - nociceptors free nerve endings
• 3 types - temperature, mechanical, chemical
• Fast pain like a needle - well localized,
  disappears fast
• not responsive to narcotics - not well
  understood
• Slow pain like a burn - difficult to localize
  and persists
• evokes autonomic reflexes emotional reactions
• Pain relief analgesic
• stops formation of prostaglandins, which
  stimulate nocireceptors
• anesthesia - block conduction of nerve impulses
• opiates- still feel but the feeling is less
  severe
• severing the nerve - spinal cord level or dorsal
  roots
• Baroreceptors - changes in pressure by free nerve
  endings
• blood (carotid artery, aorta), digestion,
  respiration, urinary

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Integrative Functions

• Learning - experience modifies centrally
  controlled behavior
• What have you learned today?

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Memory

• storage and retrieval of experience
• Fact specific bits of info
• Skill motor behaviors
• temporal lobes, hippocampus and amygdaloid
  nucleus (limbic system)
• Short-term - reverberating neuronal circuits
• lasts as long as the reverberation
• electrical and chemical and not new synapses
• Long-term - anatomical and biochemical changes -
  in cortex - specific areas
• increased NT release, facilitation at synapses
• more APs? more NT on receptors? less NT required
  at next release)
• more branching patterns and bulbs more
  synapses
• more neuroglia
• more synaptic end builds w/use
• even w/damage may still be able to access --gt
  many copies? able to rethink?
• DNA and RNA may store - RNA increases (increase
  proteins) w/memory
• Endorphins - interfere w/memory formation
• amygdala - memories and emotions
• hippocampus - short term to long term
• nucleus basalis - near diencephalon, connects to
  amygdala, hippocampus, and cortex

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Integrative Functions

• Circadian rhythm
• fatigue of neurons --gt sleep
• RAS - turned up to awake
• RAS and cerebrum keep each other awake

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Integrative Functions

• Sleep
• Awake - stimuli --gt RAS --gt stimulate cortex
• Sleep - output from RAS and input to RAS from
  regions of the brain
• brain still uses energy - as much as when awake
• increased protein synthesis
• REM - dreaming alter BP, HR, and RR
• NonREM - Deep sleep slow wave, decrease HR, BP,
  RR

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