Chapter 8: Control of Movement –Psych 211 Behavioral Neuroscience
Case Study: Mr. J: Had a severe stroke and had damage to left parietal lobe
Had severe Apraxia: Apraxia is a disorder of the brain and
nervous system in which a person is unable to perform tasks or
movements when asked, even though:
• The request or command is understood
• They are willing to perform the task
• The muscles needed to perform the task work properly
• The task may have already been learned
Was not able to wave hello when asked to do so, but could do it
automatically when meeting someone since it was something learned.
He couldn’t make even a simple movement out of context.
Left parietal lobe is involved in the control of movements-
especially sequences of movement-that are not dictated by the
Ultimate function of the Nervous System: Control of Behavior –
Making our bodies move is most important.
CONTROL OF MOVEMENT
• Movements can be initiated by several reasons, for ex.:
1. Rapid stretch of muscle triggers the monosynaptic stretch reflex
2. A stumble triggers righting reflexes
3. Rapid approach of an object toward the face causes a startle
response, a complex reflex consisting of movements of several
4. Presence of food causes eating
5. Sight of a loved one evokes a hug and a kiss Because there is no single cause of behavior, we can’t find a
single starting point in our search for the neural mechanisms
that control movement.
• The brain and spinal cord include several different, motor systems,
each of which can simultaneously control particular kinds of
ORGANIZATION OF THE MOTOR CORTEX:
• The primary motor cortex lies on the precentral gyrus, just
rostral to the central sulcus.
• Studies show that activation of neurons in particular parts of
primary motor cortex causes movements of particular parts of
• The primary motor cortex shows somatotopic organization
• Somatotopic Organization: A topographically organized mapping of
parts of the body that are represented in a particular region of the
brain. fig 8.9
NOTE: A disproportionate amount of cortical area is
devoted to movements of the fingers and the muscles
used for speech.
• Primary cortex is organized in terms of particular movements
of particular parts of the body.
Each movement may be accomplished by the contraction of
Examples: When the arm is extended in a particular
direction, many muscles in the shoulder, upper arm,
and forearm must contract.
This fact means that complex neural circuitry is
located between individual neurons in the
primary motor cortex and the motor neurons in the spinal cord that cause motor units to
The commands for movements initiated in the
motor cortex are assisted and modified-most
notable by basal ganglia and cerebellum.
• Study Graziano and Aflalo:
Found that although brief stimulation of particular
regions of the primary motor cortex of monkeys caused
brief movements of various parts of the body,
prolonged stimulation produced much more complex
EX: Stimulation of one region caused the hand to close
and then approach the mouth and then the mouth to
Stimulation of another area caused the face to
squint, the head to turn quickly to one side,
and the arms to fling up, as if to protect the face
from something that was going to hit it.
Stimulation of different zones of the motor cortex
caused different categories of action. Map of these
categories was consistent from animal to animal.
• Principal cortical input to the primary motor cortex is the
frontal association cortex, located rostral to it.
• Two regions immediately adjacent to the primary motor cortex-
the supplementary motor area and the premotor cortex- are
especially important in the control of movement.
Both regions receive sensory info from the parietal and
Both send efferent axons to the primary motor cortex.
Supplementary Motor Area (SMA): Located on the
medial surface of the brain, just rostral to the primary
motor cortex. A region of motor association cortex
of the dorsal and dorsomedial frontal lobe. Premotor Cortex: A region of motor association cortex,
located primarily on the lateral frontal lobe surface,
also just rostral to the primary motor cortex.
CORTICAL CONTROL OF MOVEMENT: THE DESCENDING PATHWAYS:
• Neurons in PMC ( primary motor cortex), control movement by
2 groups of descending tracts:
1. Lateral Group: The corticospinal tract, the corticobulbar tract,
and the rubrospinal tract.
o Primarily involved in control of independent limb
movements, particularly movements of the hands
o Independent limb movements means that the
right and left limbs make different movements, or
one limb moves while the other remains still.
o These movements contrast with coordinated limb
movements, such as those involved in
2. Ventromedial Group: The vestibulospinal tract, the tectospinal
tract, the reticulospinal tract, and the ventral corticospinal tract.
Named for their location in the white matter of the spinal cord.
o These tracts control more autonomic movements
o Gross movements of the muscles of the trunk
and coordinated trunk and limb movements
involved in posture and locomotion.
• Lateral Group:
1. Corticospinal Tract: Consists of axons of that originate in
the motor cortex and terminate in the ventral grey matter
of the spinal cord.
Largest concentration of cell bodies responsible for
these axons is located in the Primary Motor Cortex, but neurons in the parietal and temporal lobes also send
axons through the corticospinal pathway.
The axons leave the cortex and travel through
subcortical white matter to the ventral midbrain,
where they enter cerebral penduncles.
They leave the penduncles in the medulla and form the
2. Pyramidal Tracts: The portion of the corticospinal tract on
the ventral border of the medulla.
At the level of the caudal medulla, most of the fibers
decussate (cross over) and descend through the
contralateral spinal cord, forming the lateral
3. Lateral corticospinal tract: The system of axons that
originates in the motor cortex and terminates in the
contralateral ventral gray matter of the spinal cord;
controls movements of the distal limbs.
The rest of the fibers descend through the ipsilateral
spinal cord, forming the central corticospinal tract.
4. Ventral Corticospinal tract: The system of axons that
originates in the motor cortex and terminates in the
ipsilateral ventral gray matter of the spinal cord; controlz
movements of the upper legs and trunks.
Because of its location and function, it’s actually part
of the ventromedial group.
• Most axons in the lateral corticospinal tract originate in the
regions of the Primary motor cortex and supplementary motor
area that control the distal parts of the brain:
The arms, hands, and fingers and the lower leg, feet,
and toes. They form synpases, directly or via interneurons, with
motor neurons in the gray matter of the spinal cord-in
the lateral part of the ventral horn.
The motor neurons control muscles of the distal limbs,
including those that move the arms, hands, and
• Axons in ventral corticospinal tract originate in the upper leg and
trunk regions of the primary motor cortex
The descend to the appropriate region of the spinal
cord and divide, sending terminal buttons into both
sides of the grey matter
They control motor neurons that move the muscles of
the upper legs and trunk
• Corticospinal pathway controls hand and fingers movements and
is indispensable for moving the fingers independently when
reaching and manipulating.
Postural adjustments of the trunk and use of the limbs for
reaching and locomotion are unaffected; therefore these
types of movements are controlled by other systems.
EX: Monkeys having trouble releasing their grasp when
picking up objects, but having no trouble doing so
when climbing walls of cage. Can conclude that the
same behavior (opening the hand) is controlled by
different brain mechanisms in diff. contexts.
• 2ndlateral group of descending pathways: Corticobulbar Tract:
Projects to the medulla
Controls movement of the face, neck, tongue, and
parts of the extraocular eye muscles. • 3rdlateral group: Rubrospinal Tract:
The system of axons that travels from the red nucleus
to the spinal cord; controls independent limb
• 2 set of pathways originating in brain stem: Ventromedial
o Vestibulospinal tracts: A bundle of axons that travels from
the vestibular nuclei to the grey matter of the spinal cord;
controls postural movements in response to information
from the vestibular system
o Tectospinal Tracts: A bundle of axons that travels from the
tectum to the spinal cord; coordinates head and trunk
movements with eye movements.
o Reticulospinal Tracts: A bundle of axons that travels from
the reticular formation to the grey matter of the spinal cord;
controls the muscles responsible for postural movement.
PLANNING AND INITIATING MOVEMENTS: ROLE OF THE MOTOR
• Supplementary Motor Area and the Premotor cortex are involved
in the planning of movements
they execute these plans through their connections
with the primary motor cortex
Functional-imaging shows that when people execute
sequences of movements-or even imagine them-these
regions become activated Evidence indicates that the motor association cortex is
also involved in imitating the actions of other people
(an ability that makes it possible to learn new
behaviors from them) and even in understanding the
functions of other people’s behaviors.
• Supplememtary motor area and premotor cortex receive info
from association areas of the parietal and temporal cortex:
Visual association cortex organized in two streams:
1. Ventral: terminates in the inferior temporal
cortex, is involves in perceiving and recognizing
particular objects- the “what” of visual
2. Dorsal: terminates in the posterior parietal lobe,
is involved in perception of location- the “where”
of visual perception.
In addition, parietal lobes is also involved in
organizing visually guided movements-the
“how” of visual perception.
Also receives info about spatial location
from the somatosensory, vestibular, and
auditory systems and integrates this info
with visual info.
Thus, the regions of the frontal cortex that are
involved in planning movements, receive the info they
need about what is happening from the temporal and
Because the parietal lobes contain special info, the
pathway from them to the frontal lobes is especially
important in controlling both locomotion and arm and
Meaningful locomotion requires us to know where we
are , and meaningful movements of our arms and hands require us to know where objects are located in
SUPPLEMENTARY MOTOR AREA:
• Involved in learning and performing behaviors that consist of
sequences of movements. A nearby region area seems to be
involved in initiating spontaneous movements. BEHAVIORAL
Damage to this region disrupts the ability to execute
well learned sequences of responses in which the
performance of one response serves as the signal that
the next response must be made.
Chen et al. found that lesions of the supplementary
motor area severely impaired monkeys’ ability to
perform a simple sequence of two responses: pushing
a lever in and then turning it to the left, receiving a
peanut after each response.
Single unit study came to similar conclusion:
o Monkeys were trained to perform a memorized
series of responses, pressing each of three
buttons in a specific sequence.
o While monkeys were performing task, more than
half of the neurons in the supplementary motor
area became activated.
o However, when the sequence was cued by visual
stimuli-the monkeys simply had to press the
button that was illuminated-these neurons
showed little activity.
Shima and Tanji (2000) taught monkeys 6 sequences of
three motor responses:
o For ex, one of the sequences was push, then pull,
then turn. o They recorded from neurons in the
supplementary motor area found neurons whose
activities appeared to encode elements of these
o For ex, some neurons responded just before a
particular sequence of three movements
occurred; some neurons responded between two
particular responses, and some neurons
responded as the monkey was preparing to make
the last response of the sequence.
o Presumably, these neurons were members of
circuits that encoded the info necessary to
perform the six sequences.
Shima &Tanji (1998) temporarily inactivated the
supplementary motor area in monkeys with injections
of muscimol, a drug that stimulates GABA receptors
and thus inhibits neural activity.
o They found that after inactivation of this region,
monkeys could still reach for objects or make
particular movements in response to visual cues
but could no longer make a sequence of three
movements they had previously learned.
Funtional-imaging study by Hikosaka et al. :
o Observed increased activity in the posterior SMA
during performance of a learned sequence of
Gerloff et al. taught people to make a sequence of 16
finger presses on a piano:
o When the researcherts disrupted the activity of
the SMA with transcranial magnetic stimulation,
the performance of the sequence was disrupted.
o However, disruption was not immediate: The
subjects continued the sequence for approx. 1 sec. and then stopped, saying they “didn’t know
anymore which series of keys to press next”
o Apparently, SMA is involved in planning the
elements yet to come in sequences of movements
o Actual execution of these movements seems to
be controlled by the primary motor cortex.
o A region just anterior to the supplementary motor
o Appears to be involved in control of spontaneous
o Has long been known that although electrical
stimulation of the motor cortex causes
movements, it does not produce the desire to
o Movement is perceived as automatic and
o In contrast, electrical stimulation of the medial
surface of the frontal lobes ( including SMA and
pre-SMA) often provokes the urge to make a
movement or at least the anticipation that a
movement is about to occur.
o Functioning-imaging study by Lau et al. :
Found that the pre-SMA became active just
before people performed spontaneous
Experimenters asked subjects to make a
finger movement from time to time,
whenever they felt like doing so.
The subjects watched a red light that moved
around a clock face at about 2,5 sec per
revolution. They were asked to pay attention to the
instant when they decided to make the
movement and report the position of the red
dot at that time.
The decision appeared to occur 0.2 sec.
before the movement began, however fMRI
showed that the activity of the pre-SMA
actually began to increaser 2-3 sec. earlier
This suggests that the neural activity
responsible for the decision to move begins
before a person is even aware of making
The most important input to the SMA comes from the
o Sirigu et al. (2004) used a task similar to the one
in the study by Lau et al. to investigate decision
making in people with lesions of the parietal
o They found that people with parietal lesions could
accurately report when they started the
movements, but they were not aware of an
intention to move prior to making the movement.
o These results suggest that info received from the
parietal lobes permits the pre-SMA to detect that
a decision to move has been made.
o Location of the neural circuits actually
responsible for the decision are not known,
although Sirigu and her colleagues note that
lesions of the prefrontal cortex (even more
anterior than the pre-SMA) disrupt people’s plans
for voluntary action.
o People with prefrontal lesions will react to events
but show deficits in initiating behavior so perhaps the prefrontal cortex is an important source of
• Involved in imitating responses of other people and in
understanding and predicting these actions
• Involved in learning and executing complex movements that
are guided by sensory information.
• Studies suggest that the premotor cortex is involved in using
arbitrary stimuli to indicate what movement should be made
EX: Reaching for an object that we see in a particular
location involves nonarbitrary spatial information
That is, the visual information provided by the location
of the object specifies just where we should target our
• We also have ability to learn to make movements based on
arbitrary information- information that is not directly related
to the movement that it signals.
EX: A person can point to a particular object when
someone says its name, or a dancer can make a
particular movement when asked to do so by a
Diff. languages use diff. sounds to indicate the names
of objects, and diff. choreographers could invent diff.
names for movements used in their dancers.
The association between these stimuli and the
movements they designate are arbitrary and must be
• Kurata &Hoffman (1994) trained monkeys to move their hands
toward the right or left in response to either spatial or a non-
spatial signal: The spatial signal required a monkey to move in the
direction indicated by signal lights located on the right
or left of the hand.
The non-spatial signal consisted of a pair of lights, one
red and one green, located in the middle of the
o Red light signaled a movement to the left, and
green light signaled a movement to the right.
o The investigators temporarily inactivated the
premotor cortex with injections of muscimol.
o When this region was inactivated, the monkeys
could still move their hands towards a signal light
located to the left or right (a non-arbitrary
signal), but they could no longer make the
appropriate movements when the red or green
signal lights were illuminated
o Similar results seen in people with damage to
o Halsband and Freund (1990):
Found that patients with lesions in
premotor cortex could learn to make 6
different movements in response to spatial
cues, but not to arbitrary visual cues.
That is, they could learn to point one of six
locations in which they had just seen a
visual stimulus, but they could not learn to
use a set of visual, auditory, and tactile
cues to make particular movements.
IMITATING AND COMPREHENDING MOVEMENTS: ROLE OF THE
MIRROR NEURON SYSTEM: • Rizolatti et al (2000) Found that neurons in an area of the
rostral part of the ventral premotor cortex in the monkey brain
(area F5) became active when monkeys saw people or other
monkeys perform various grasping, holding, or manipulating
movements or when they performed these movements
Thus, the neurons responded to either the sight or the
execution of particular movements.
Investigators named these cells mirror neurons.
o The location of these neurons, the ventral
premotor cortex, is reciprocally connected with
the inferior parietal lobule, a region of the
posterior parietal lobe, and further investigation
found that this region also contains mirror
o Given the characteristics of mirror neurons, we
might expect that they play a role in a monkey’s
ability to imitate the movements of other
monkeys, which was found to be true by Rizolatti.
o Mirror Neurons: Neurons located in the ventral
premotor cortex and inferior parietal lobule that
responds when the individual makes a particular
movement or sees another individual making that
• Several fMRI studies have shown that the human brain also
contains a circuit of mirror neurons in the inferior parietal
lobule and the ventral premotor area.
EX: in a fMRI study, Buccino et al. asked nonmusicians
to watch and then imitate video clips of an expert
guitarist placing his finger son the nexk of a guitar to
play a chord.
Investigators found that both watching and imitating
the movements activated the mirror neuron circuit. Studies have shown that the mirror neuron system is
activated more strongly when one is watching a
behavior in which one is already competent.
• Mirror neurons are activated not only by the performance of an
action or the sight of someone else performing that action, but
also by sounds that indicate the occurrence of a familiar
Kohler et al. found that mirror neurons in the ventral
pre-frontal cortex of monkeys became active when the
animals heard sounds they recognized, such as
peanuts breaking, a piece of paper being ripped, or a
stick beign dropped.
Individual neurons-the researchers called them
audiovisual neurons- responded to the sounds of
particular actions and to the sight of those actions.
Presumably, activation of these neurons by these
familiar sounds reminds the animals of the actions the