Transcript Movement

James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Chapter Eight
Movement
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
2 of 34
Muscles and Their Movements
•
•
Smooth muscles control internal organs
– long thin cells
Skeletal or striated muscles control movement of body in
relation to the environment
– long cylindrical with stripes
– neuromuscular junction: synapse of motor neuron with
muscle fiber
• axons release acetylcholine at synapse
– each muscle moves in one direction and in absence of
acetlycholine it relaxes
– movement in two directions requires antagonistic
muscles: flexor to raise arm and extensor to lower arm
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.3
Figure 8.3 A pair of antagonistic muscles. The biceps of the arm is a flexor; the triceps is an extensor.
(Source: From Biology: The Unity and Diversity of Life, 5th Edition, by C. Starr and R. Taggert, p.331.
Copyright © 1989 Wadsworth. Reprinted by permission.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Muscles and Their Movements cont.
•
•
Cardiac or heart muscles
– fibers that fuse together at points
– somewhat between smooth and skeletal muscles
Myasthenia Gravis is autoimmune disease
– immune system anti-bodies attack acetylcholine
receptors;
– weakness and rapid fatigue of muscles because motor
neurons can’t constantly produce maximum acetylcholine
– treated by drugs that inhibit acetylcholinesterase to
prolong acetylcholine
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Muscles and Their Movements cont.
•
•
Fish
– white muscles: fast contractions, easily fatigued, needed
to maintain speed in cold water
– pink muscles: intermediate speed contractions, less easily
fatigued, used to support activity in warm-cool water
– red muscles: slow contractions, resistant to fatigue, relies
on red muscles in warm water
Human
– fast twitch fibers: fast contractions, easily fatigued,
increased by sprinting
– slow twitch fibers: slow contractions resistant to fatigue,
increased by long-distance running
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Muscles and Their Movements cont.
•
Proprioceptors: receptor that is sensitive to the position or
movement of a part of the body
– muscle spindle: senses stretch of muscle and sends
negative feedback to motor neuron to contract
– golgi tendon organ: senses increase in muscle tension
and sends message to inhibit motor neuron and brake
contraction
– knee jerk: tap stretches spindle and feedback jerks leg up
– loss of proprioceptor
• no automatic control from sensors
• requires constant visual monitoring to provide
feedback
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.5
Figure 8.5 Two kinds of proprioceptors regulate the contraction of a muscle. When a muscle is
stretched, the nerves from the muscle spindles transmit an increased frequency of impulses, resulting in a
contraction of the surrounding muscle. Contraction of the muscle stimulates the Golgi tendon organ, which
acts as a brake or shock absorber to prevent a contraction that is too quick or extreme.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Voluntary and Involuntary Movements
•
•
Reflexes such as the stretch reflex or constriction of pupil to
light are involuntary
– infant reflexes include rooting, grasp, and Babinski
– allied reflexes are strong in infants and still in adults, e.g.,
sneezing, closing eyes in strong sunlight
Most movements, e.g., walking, are a combination of
voluntary and involuntary muscle control
– involuntarily adjust to irregularities in road and
automatically swing your arms
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Sensitivity to Feedback
•
•
Ballistic movements, e.g., reflexes, cannot be altered once
started
Central pattern generators
– neural mechanisms in spinal cord and elsewhere that
generate rhythmic patterns, e.g., wing flapping in birds
and fin movements in fish
– started by stimulus but motor program sets frequency of
movement, e.g., cats scratch themselves 3-4 times/sec
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Sensitivity to Feedback cont.
•
Motor program is a fixed sequence of movements
– Ex: cat washing face, gymnast with complex movements,
yawn
– automatic patterns may be disrupted when thinking about
them, e.g., typing or playing piano
– evolutionary holdover: chicken still flaps wings when
dropped even though can’t fly
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Cerebral Cortex
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•
Cerebral cortex important for complex actions such as writing
– less voluntary movements e.g., coughing, laughing, crying
are controlled by subcortical areas
Stimulation of primary motor cortex elicits certain outcome
movements in corresponding body area
– 500 msec stimulation of arm region of monkey results in
grasping movement and moving hand toward head
– also, finger area of cortex active when pianist hears music
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Cerebral Cortex cont.
•
•
Posterior parietal cortex keeps track of position of body
relative to environment
– if damaged we can describe what we see but can’t walk
toward it, pick it up, or step over object
Primary somatosensory cortex is main receiving area for
touch and other body information
– responds to shape of object and grasping, lifting or
lowering
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Cerebral Cortex cont.
•
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•
Prefrontal cortex active when planning and calculating
possible outcomes of a movement
– damage results in badly planned movements, showering
with clothes on, salting tea instead of food, etc.
– inactive during dreaming and dreams are usually
haphazard
Premotor cortex is active during preparations for a movement
– receives information about target and body location
Supplementary motor cortex active during preparations for a
rapid series of movements; typing, dancing, speaking,
playing musical instrument
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.8
Figure 8.8 Principal areas of the motor cortex in the human brain. Cells in the premotor cortex and
supplementary motor cortex are active during the planning of movements, even if the movements are never
actually executed.
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.9
Figure 8.9 Map of body areas in the primary motor cortex. Stimulation at any point in the primary motor
cortex is most likely to evoke movements in the body areas shown. However, actual results are usually
messier than this figure implies: For example, individual cells controlling one finger may be intermingled
with cells controlling another finger. (Source: Adopted from Penfield & Rasmussen, 1950.)
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Connections From Brain to Spinal Cord
•
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Messages from brain reach the medulla and spinal cord
through dorsolateral or ventromedial tracts
Dorsolateral (pyramidal tract)
– originate from primary motor cortex, surrounding areas
and red nucleus
– in pyramids of medulla, axons cross over to opposite side
of spinal cord but contralateral control develops gradually
• clumsiness in children with cerebral palsy comes from
competition between contralateral and ipsilateral paths
– controls movement in hands, fingers, toes
– damage here means loss of fine movements
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.11
Figure 8.11 The dorsolateral tract. This tract originates from the primary motor cortex, neighboring areas,
and the red nucleus. It crosses from one side of the brain to the opposite side of the spinal cord and
controls precise and discrete movements of the extremities, such as hands, fingers, and feet.
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Connections From Brain to Spinal Cord cont.
•
Ventromedial tract
– includes axons from the primary and supplementary
motor cortex, midbrain tectum, reticular formation and
vestibular nucleus
– do not cross to contralateral side because axons control
bilateral movement of the neck, shoulders, and trunk
– damage here impairs walking, turning, bending, standing
up and sitting down
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Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.12
Figure 8.12 The ventromedial tract. This tract originates from many parts of the cerebral cortex and
several areas of the midbrain and medulla. It produces bilateral control of trunk muscles for postural
adjustments and bilateral movements such as standing, bending, turning, and walking.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Cerebellum
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•
Important for motor control and has more neurons than rest
of brain
Enhances new motor programs and skills
Processes information about guiding movement, not the
movement itself
– active when weighing objects with hands or when objects
rub hands
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Cerebellum cont.
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•
Damage causes difficulty with:
– rapid, ballistic movements, sequences that require
accurate aiming and timing, e.g., tapping rhythm,
speaking, writing, playing musical instrument
– finger-to-nose task: initial rapid movement may strike face
or hold segment of task may waver, as when intoxicated
– judging differences in delay in pairs of tones
– normal shifting of attention within 100 msec: may take up
to a second
Damage does not effect controlling force of movement or
judging loudness of tones
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Cellular Organization in Cerebellum
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•
Receives input from the spinal cord, sensory systems
through the cranial nerve nuclei, and from the cerebral cortex
Cells are arranged in precise, repeating geometrical patterns
– Purkinje cells are very flat and exist in sequential planes
– parallel fibers are perpendicular to the planes of the
Purkinje cells
– parallel fibers excite Purkinje cell
• the more excited, the longer the duration of the
Purkinje output which may control either a movement
or a cognitive process
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.14
Figure 8.14 Cellular organization of the cerebellum. Parallel fibers (yellow) activate one Purkinje cell
after another. Purkinje cells (red) inhibit a target cell in one of the nuclei of the cerebellum (not shown, but
toward the bottom of the illustration). The more Purkinje cells that respond, the longer the target cell is
inhibited. In this way the cerebellum controls the duration of a movement.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Basal Ganglia
•
Basal ganglia: group of large subcortical structures in the
forebrain
– caudate nucleus and putamen receive input from
thalamus and cortex
– globus pallidus sends information to the thalamus where it
goes on to the motor and premotor cortices
– stores sensory information to guide movements, learn
rules and organize sequences of movements into a
smooth, automatic whole
• Organize action sequence into chunks or units like
learning to drive a car (habit learning)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Role of Basal Ganglia cont.
•
•
Active in selection or inhibition of movements, e.g.:
– surgery patients had activity when they made a
movement with finger in response to signal
– drawing a new line on computer
Linked to obsessive-compulsive disorder
– OCD is marked by repetitive thoughts and actions that
person knows is pointless or nonsensical
– OCD increases activity in caudate nucleus and this may
be linked to strong habits
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.15
Figure 8.15 Location of the basal ganglia. The basal ganglia surround the thalamus and are surrounded
by the cerebral cortex.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Parkinson’s Disease
•
•
Gradual progressive death of neurons especially in
substantia nigra
– decrease in dopamine results in decreased excitation of
cerebral cortex
Symptoms begin when neurons decrease 20%-30%
– slow on cognitive tasks
– some depression and cognitive deficits but no emotional
outbursts
– rigidity, muscle tremors, slow movements and difficulty
initiating physical and mental activity
• but patients function well with visual cues, e.g., follow
parade, climb stairs and step on lines at fixed intervals
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.17
Figure 8.17 Connections from the substantia nigra: (a) normal and (b) in Parkinson’s disease.
Excitatory paths are shown in green; inhibitory are in red. The substantia nigra’s axons inhibit the putamen.
Axon loss increases excitatory communication to the globus pallidus. The result is increased inhibition from
the globus pallidus to the thalamus and decreased excitation from the thalamus to the cerebral cortex.
People with Parkinson’s disease show decreased initiation of movement, slow and inaccurate movement,
and psychological depression. (Source: Based on Wichmann, Vitek, &Delong, 1995.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Parkinson’s Disease cont.
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•
Possible Causes
– genetics
• early onset in identical twin good predictor for other
twin but less so after 50 years of age
• 5 genes more common in patients but no specific
gene for disease
– one cause is exposure to toxins, e.g., MPTP designer
drug which destroys dopamine releasing neurons
Smoking and caffeine decreases risks
– inconsistent findings for caffeine
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Figure 8.18
Figure 8.18 Probability of developing Parkinson’s disease if you have a twin who developed the
disease before or after age 50. Having a monozygotic (MZ) twin develop Parkinson’s disease before age
50 means that you are very likely to get it too. A dizygotic (DZ) twin who gets it before age 50 does not pose
the same risk. Therefore early-onset Parkinson’s disease shows a strong genetic component. However, if
your twin develops Parkinson’s disease later (as is more common), your risk is the same regardless of
whether you are a monozygotic or dizygotic twin. Therefore late-onset Parkinson’s disease has little or no
heritability. (Source: Based on data of Tanner et al., 1999.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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L-Dopa Treatment
•
Most common treatment
– precursor for dopamine that crosses blood-brain barrier
– effective in early to intermediate stages but some patients
do not benefit at all
– does not stop progression of the disease, may do harm
– side effects: nausea, restlessness, sleep problems, low
blood pressure, hallucinations, and delusions
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Other Treatment
•
One or more of following usually combined with L-Dopa
– drugs: antioxidants, dopamine receptor stimulants,
glutamate blockers, drugs that decrease apoptosis,
– electrical stimulation of globus pallidus, or surgery
– neurotrophins to promote growth of remaining neurons
– cell transplants
• most successful with substantia nigra cells
transplanted from fetuses into young rats
• slight benefits with fetal brain transplants to patients
• neurotrophins may help if researchers can get them
past blood-brain barrier
James W. Kalat
Biological Psychology, 8th Edition
Chapter 8: Movement
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Huntington’s Disease
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Severe neurological disorder striking 1 in 10,000
Extensive damage to caudate nucleus, putamen, and globus
pallidus, and some in the cerebral cortex
Symptoms most often appear between 30-50 years
– begin with jerky arm movements, then facial twitch, later
tremors spread and develop into writhing
– cannot learn new or improve movements
– includes depression, memory impairment, anxiety,
hallucination
• may be misdiagnosed as schizophrenic