CHAPTER 15 NEURAL INTEGRATION

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CHAPTER 15NEURAL INTEGRATION
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SENSORY INTEGRATION FROM RECEPTION TO PERCEPTION

• 1. survival depends on
• a. sensation - awareness of changes
• b. perception - conscious interpretation of the
  stimuli
• 2. somatosensory system - deals with reception in
  the body wall and limbs
• a. input from exteroceptors, interoceptors and
  proprioceptors

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SENSORY INTEGRATION

• 3. three levels of integration in somatosensory
  system
• a. receptor level - sensory receptors
• b. circuit level - ascending pathways
• c. perceptual level - cerebral cortex

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SENSORY INTEGRATION

• 4. receptor level processing
• a. sensory receptors respond to
• 1. sound
• 2. mechanical
• 3. chemical
• 4. light
• 5. touch
• 6. pain

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SENSORY INTEGRATION

• 5. transduction - conversion of stimulus energy
  into electrical energy
• 6. circuit level processing
• a. sensory fibers branch as they enter the spinal
  cord
• b. some branches form reflexes
• c. others move up to higher brain centers
• 1. nonspecific pathways - inputs from many types
  of receptors
• 2. specific pathways - precise input from a
  single type of receptor

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6. circuit level processing

• d. pathways relay info for three purposes
• 1. perception
• 2. arousal
• 3. motor control
• e. separate pathways allow for
• 1. same info to be handled in different ways
  (richness in perception)
• 2. provide insurance against damage

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SENSORY INTEGRATION

• 7. perceptual level processing
• a. involves awareness of stimuli and
  discrimination of their characteristics
• b. thalamus - origins of inputs are localized
• 1. sends impulses to primary somatosensory cortex
  and sensory association areas
• c. sensory input generally results in a
  behavioral response
• 1. in humans, a response in not obligatory

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7. perceptual level processing

• d. main aspects of perception
• 1. detection
• 2. magnitude estimation
• 3. spatial discrimination
• 4. feature abstraction
• 5. quality discrimination
• 6. pattern recognition

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SENSORY INTEGRATION

• 8. perceptual detection - detecting that a
  stimulus has occurred
• a. several receptor impulses must be summated
• 9. magnitude estimation - ability to detect how
  much of the stimulus is acting on the body
• 10. spatial discrimination - allows
  identification of site or pattern of stimulation
• a. two-point discrimination test

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SENSORY INTEGRATION

• 11. feature abstraction - mechanism by which a
  neuron or circuit is tuned to one feature in
  preference to another
• a. feature - coordinated set of several stimulus
  properties
• b. gives ability to identify texture or shape

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SENSORY INTEGRATION

• 12. quality discrimination - ability to
  differentiate submodalities of a particular
  sensation
• a. major achievement of our sensory system
• b. analytic discrimination - each quality retains
  its individual nature
• c. synthetic discrimination - different receptors
  stimulated to achieve one perception
• 1. vision
• 2. olfaction

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SENSORY INTEGRATION

• 13. pattern recognition - ability to take in a
  scene and recognize patterns as familiar or
  unfamiliar or special significance

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MOTOR INTEGRATION FROM INTENTION TO EFFECT

• 1. system consists of
• a. effectors
• b. descending efferent circuits
• c. motor behavior
• 2. motor hierarchy - refers to multiple and
  successive levels of motor control
• 3. cerebral cortex
• a. instrument of volition
• b. at highest level of conscious motor pathways

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MOTOR INTEGRATION

• 4. cerebellum and basal nuclei
• a. planners and coordinators of complex motor
  activity
• b. some activities mediated by reflex arcs
• 5. fixed action patterns - sequential motor
  actions generated internally or triggered by
  environmental stimuli
• 6. three levels of motor control
• a. segmental level
• b. projection level
• c. programs/instructions level

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MOTOR INTEGRATION

• 7. segmental level
• a. lowest level
• b. causes stimulus of a specific group of muscle
  fibers
• c. central pattern generators (cpgs) - control
  locomotion
• d. regulated by a "switch" in higher neural
  centers - command neurons

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MOTOR INTEGRATION

• 8. projection level
• a. controls spinal cord
• b. houses command neurons
• c. command neuron - interneuron that can activate
  a unique fragment of coordinated behavior by
  exciting or inhibiting specific spinal cord
  neurons
• 1. start, stop, or modify basic rhythm of cpgs
• d. direct pyramidal system - projection level
  neurons of the cerebral cortex
• 1. work via pyramidal tracts lesion cause
  hypotonia
• e. indirect pyramidal system - all motor pathways
  except the pyramidal tracts
• 1. set main patterns of day by day behavior

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MOTOR INTEGRATION

• 9. programs/instructions level
• a. regulate motor activity
• 1. precisely start or stop movements
• 2. coordinate movements with posture
• 3. block unwanted movements
• 4. monitor muscle tone
• b. precommand areas - control outputs of cortex
  and brain stem motor centers
• 1. highest level of control
• c. sensory and motor systems are integrated

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9. programs/instructions level

• d. cerebellum - key center for sensorimotor
  integration and control
• 1. acts through projection areas of brainstem
• e. basal nuclei - regulate motor activities
  initiated by cortical neurons
• 1. receive inputs from all cortical areas and
  send output back to premotor and prefrontal areas
  of cortex
• 2. liaison between cerebral cortex and cerebellum
  in planning and initiation of motor activity

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HOMEOSTATIC IMBALANCES OF MOTOR INTEGRATION

• 1. damage to cerebellum falls into 3 groups
• a. disorders of synergy and muscle tone
• b. disturbances of equilibrium
• c. speech disorders
• 2. synergy - coordination of antagonistic muscles
  to produce a smooth movement
• a. ataxia - disruption of synergy slow,
  tentative, inaccurate movements
• b. lack of check - loss of muscle tone and
  resistance to movement limb unable to stop
  quickly and sharply

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HOMEOSTATIC IMBALANCES

• 3. scanning speech - slurred and slow speech
  singsong in nature
• 4. diseases involving basal nuclei
• a. dyskinesia - disorders of muscle tone and
  posture as well as involuntary movements
• b. Parkinson's disease - inadequate dopamine
  synthesis
• 1. L-dopa
• 2. deprenyl
• 3. intrabrain transplants
• c. Huntington's Disease - hereditary disorder
  degenerative

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HIGHER MENTAL FUNCTIONS

• 1. mind - higher mental functions of
  consciousness, memory, reasoning and language
• 2. Electroencephalogram - EEG - record of brain
  wave activity

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HIGHER MENTAL FUNCTIONS

• 3. brain waves - patterns of neuronal electrical
  activity
• a. alpha waves - low amplitude, slow,
  synchronous calm relaxed state
• b. beta waves - awake and mentally alert
  concentration and visual stimulus
• c. theta waves - common in early stages of sleep
  abnormal in adults who are awake
• d. delta waves - deep sleep RAS is dampened

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HIGHER MENTAL FUNCTIONS

• 4. characteristics of brain waves
• a. amplitude reflects number of neurons firing
  together in synchrony
• b. unconsciousness occurs in both too fast and
  too slow wave activity
• 5. epilepsy - abnormal electrical discharges of
  groups of brain neurons

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HIGHER MENTAL FUNCTIONS

• 6. types of seizures
• a. petit mal - mild usually in young children
• b. psychomotor epilepsy - rapid temporal lobe
  brain waves loss of reality uncontrolled motor
  activity of isolated muscle groups
• c. grand mal - loss of consciousness intense
  convulsions

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SLEEP AND SLEEP-AWAKE CYCLES

• 1. circadian rhythm - about a 24 hr. cycle
• 2. sleep - state of changed consciousness from
  which a person can be aroused by stimulation
• a. brain stem functions maintained
• 3. coma - unconsciousness no arousal by any type
  of stimulation
• 4. awake - alertness of cerebral cortex
• a. mediated by RAS

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SLEEP

• 5. stages of sleep
• a. NREM sleep - four stages
• b. REM sleep
• 6. NREM sleep - non rapid eye movement (Table
  15.1, p527)
• 7. REM sleep (paradoxical sleep)
• a. EEG pattern typical of awake state
• b. increases in blood pressure, temperature,
  heart rate, respiratory rate
• c. decreases in gastrointestinal motility
• d. most muscles are actively inhibited

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SLEEP

• 8. importance of sleep
• a. slow wave sleep is restorative
• b. REM sleep may be to analyze events work
  through problems reverse learning
• 9. homeostatic imbalances of sleep
• a. narcolepsy - involuntary sleep during waking
  hours
• b. insomnia - chronic inability to obtain the
  amount or quality of sleep needed

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CONSCIOUSNESS

• 1. encompasses
• a. conscious perception of sensations
• b. voluntary initiation and control of movement
• c. higher mental processing
• 2. clinical consciousness defined as levels of
  behavior in response to stimulus
• a. alertness
• b. drowsiness or lethargy
• c. stupor
• d. coma

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CONSCIOUSNESS

• 3. holistic information processing
• a. consciousness involves simultaneous activity
  of large areas of the cerebral cortex
• b. consciousness is superimposed on other types
  of neural activity
• c. consciousness is totally interconnected
• 4. fainting - transient loss of consciousness
• a. inadequate cerebral blood supply
• 5. coma

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MEMORY

• 1. storage and retrieval of previous experience
• 2. essential for learning and behavior
• 3. three principles of memory and learning
• a. memory storage occurs in stages and is
  continually changing
• b. hippocampus and surrounding structures play a
  role
• c. memory traces are widely distributed in the
  brain

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MEMORY

• 4. stages of memory
• a. STM
• b. LTM
• 5. short term memory
• a. fleeting memory of events
• b. lasts seconds to hours
• c. limited to 7 or 8 chunks of information

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MEMORY

• 6. long term memory
• a. appears limitless in capacity
• b. ability declines with age
• 7. transfer of information from STM to LTM
  includes
• a. emotional state
• b. rehearsal
• c. association of new info with old info already
  in LTM
• d. automatic memory

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MEMORY

• 8. memory consolidation - process of transfer
  from STM to LTM
• a. may involve fitting new facts into various
  categories of knowledge
• 9. categories of memory
• a. fact memory - learning explicit information
• b. skill memory - less conscious learning
  involves motor activities

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MEMORY

• 10. brain structures involved in memory
• a. fact memory
• 1. hippocampus - learning and remembering spatial
  relationships
• 2. amygdala - gatekeeper of the memory system
  links memory formed by different senses
• 3. diencephalon (thalamus hypothalamus)
• 4. ventromedial prefrontal cortex
• 5. basal forebrain
• b. damage to either hippocampus or amygdala
  results in slight memory loss
• c. bilateral destruction - of both causes global
  amnesia

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MEMORY

• 11. anterograde amnesia - here and now new
  memories do not form
• 12. retrograde amnesia - loss of memories formed
  in the distant past

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MEMORY

• 13. mechanisms of memory
• a. engram - memory trace
• b. STM - may use
• 1. reverberating circuits
• 2. intracellular regulatory chemicals
• c. LTM - may use
• 1. alteration of neuronal ribonucleic acid
• 2. change in shape of dendritic spines
• 3. extracellular proteins deposited at synapses
• 4. removal of certain neuronal inhibitory
  controls
• 5. newly discovered nmda receptors

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LANGUAGE

• 1. most distinctly human functions involve
  language directly or indirectly
• 2. language may involve specific brain areas as
  well as parallel pathways and areas