specifies movement goals sends sensory information from vision, touch and hearing into the frontal regions via multiple routes relatively automatic movements can be executed, but movements requiring conscious control takes indirect routes through temporal and frontal cortex

immediately anterior to M1 houses a movement repertoire, its own lexicon, that: recognizes others' movements selects similar or different actions organizes whole body movements

Chapter 9 Flashcards by Adriana Ho

How well did you know this?

Not at all

Perfectly

motor system process

list the pieces

How well did you know this?

Not at all

Perfectly

posterior cortex

specifies movement goals
sends sensory information from vision, touch and hearing into the frontal regions via multiple routes
relatively automatic movements can be executed, but movements requiring conscious control takes indirect routes through temporal and frontal cortex

How well did you know this?

Not at all

Perfectly

prefrontal cortex

On instructions from the posterior cortex, the PFC, prefrontal cortex, generates plans for movements that it passes along to the premotor and motor cortex

How well did you know this?

Not at all

Perfectly

premotor cortex

immediately anterior to M1
houses a movement repertoire, its own lexicon, that:
- recognizes others’ movements
- selects similar or different actions
organizes whole body movements

How well did you know this?

Not at all

Perfectly

primary motor cortex (MI) / bordmann’s area 4

more elementary movements than premotor lexicon, including hand and mouth movements

motor cortex calculates both the direction and the distance of movements

How well did you know this?

Not at all

Perfectly

simple movement

If a movement is relatively simple, then the premotor and motor cortex execute the action.

How well did you know this?

Not at all

Perfectly

movement sequence

If planning is required, the temporal and prefrontal cortices make decisions, and then the premotor and motor cortices execute the appropriate movements.

How well did you know this?

Not at all

Perfectly

Rolan 1993

hierarchical control of movement in brain

used cerebral blood flow, serving as an indicator of neural activity, to illustrate neocortical motor control of simpler versus more complex movements

How well did you know this?

Not at all

Perfectly

motor homunculus (Penfield 1950s)

Because the body is symmetrical, each hemisphere contains an almost mirror image representation of this homunculus.
located a secondary homunculus in the supplementary motor cortex
motor homunculus is upside-down relative to the actual body, with the feet located dorsally within the central fissure and head located ventrally, just above the lateral fissure
the arrangement of body parts is somewhat different from that of the real body
There may be as many as 10 homunculi within the motor and premotor cortices, and parts of the homunculi are arranged as simply as Penfield sketched them

How well did you know this?

Not at all

Perfectly

Graziano (2009)

used trains of electrical stimulation of 0.5 seconds in conscious monkeys
- found that stimulating elicits action that he calls ethological categories of movement
  - each region represents three types of organization:
    - the body part to be moved
    - the spatial location to which the movement is directed
    - the movement’s function
shows that many cortical maps of the body exist, but each map represents a different action: the part of space in which an action is to take place and that action’s intended function
- but certain movement types, for example reaching, cluster together relative to the partof motor cortex from which they are elicited
graziano’s topography is consistent with Penfield’s map and with the idea that whole body movements are represented in the premotor cortex and more discrete movements in the motor cortex

How well did you know this?

Not at all

Perfectly

parietal cortex

Kaas 2013

motor cortex is not the only region from which movements can be evoked
- Similar functional movements can be elicited by electrically stimulating the parietal cortex
- parietal topography mirrors the motor homunculus
stepping movements - dorsal parietal regions
reaching movements - medial parietal regions
hand and mouth movements - ventral parietal regions

How well did you know this?

Not at all

Perfectly

parietal cortex Kaas ex

to guide reaching to a target:
the visual cortex has to identify both the location of an object and the object itself
visual cortex instructs parietal arm region about object’s location and hand region about how to shape the digits to grasp the object
parietal regions will activated when the object is contacted
reach and grasp regions of the parietal cortex then connect to reach and grasp regions of the motor cortex that will produce the movement over descending pathways to the spinal cord
Similarly various combination of activity in parietal to motor cortex pathways underlie the complexity of our movements

How well did you know this?

Not at all

Perfectly

lexicon

and other support

repertoire of movements categories in the cortex

most primate species use this same grip pattern
people who have incurred small lesions of the motor cortex around the thumb region of the homunculus, have weaknesses not only in the thumb but in the other fingers and in the arm as well
- suggested to Schiebe that the lesion impair not the hand or individual digit muscle but rather the coordinated action of reaching for and grasping an object
  - After incurring a lesion in which the pincer grip is lost,a person is likely to substitute any movement. A whole hand grip. The premotor cortex and the primary motor cortex share a common movement lexicon. And the repertoire available to the premotor cortex,is just more complex than that of M1.

How well did you know this?

Not at all

Perfectly

Brinkman 1984

premotor cortex

showed that damage to the premotor cortex does not produce muscle weakness but it does disrupt more complex movements
premotor cortex plays greater role in organizing whole body movements than M1

How well did you know this?

Not at all

Perfectly

Fukuda 1981

learning to move

suggested that a large part of learning to move entails learning how to use pre-organized movement patterns to achieve both skill and strength
Part of the role of the neocortex in movement must thus be to blend together motor reflexes to form learned skilled actions.

How well did you know this?

Not at all

Perfectly

Evarts 1968

motor cortex cells

investigate how motor cortex cells are involved in movement
trained a monkey to flex its wrist to move a bar which differing weights could be attached

neurons begin to discharge even before the monkey flexes its wrist
1. participate in planning the movement as well as in initiating it
neurons continue to discharge during the wrist movement, confirming that they also play a role in executing it
neurons also discharge at a higher rate when the bar is loaded with a weight

indication that motor cortex neurons increase the force of a movement by increasing their firing rate
motor cortex specifies movement direction
movements are not produced simply by the action of a single cell but rather by the coordinated activity of populations of cells

How well did you know this?

Not at all

Perfectly

Gerogopoulos (1999)

monkeys pt 2

trained monkeys to move a lever in different directions across the surface of a table as shown in the figure
- recording from single cells in the arm region of the motor cortex
found that each neuron is maximally active when the monkey moves its arm in a particular direction
As a monkey’s arm moves in directions other than the one to which a particular cell maximally responds, the cell decreases its activity in proportion to the displacement from the preferred direction.
> motor cortex calculates both the direction and the distance of movements

How well did you know this?

Not at all

Perfectly

Mita 2001

monkeys and mirrors

recorded the activity of cell in the monkey’s motor system involved in social interactions
identified that a subset of neurons in the ventral premotor area, discharge not only when the monkey itself makes a movement, but also when the monkey sees other monkeys make the same movement
- and even when monkey sees people, it makes the same movement

How well did you know this?

Not at all

Perfectly

mirror system neurons

cells in primary premotor cortex fire when an individual observes a specific action taken by another individual
encode the goal of an object - do not respond to objects, isolated hand movements, pictures or videos

How well did you know this?

Not at all

Perfectly

(human) core mirror system

transitive (respond to actions that obtain goal objects)

more broadly tuned

How well did you know this?

Not at all

Perfectly

distributed mirror neuron system

responds to intransitive actions (movement in which a goal is not present)

flexible properties of mirror neurons underlie our inner ability to imagine movements, the ability to understand the actions of others
we understand our own actions and those of others by internally replicating the movements
Our cognitive understanding of an action is embodied in the neural system that produce that action

How well did you know this?

Not at all

Perfectly

Salatin 2014

mirror neuron system

suggested that some symptoms of some disorders are related to the mirror neuron system
ex: the absence of empathy, the ability to see other points of view, which occurs for example, in cases of autism spectrum disorder, may be related to mirror neuron system dysfunction

How well did you know this?

Not at all

Perfectly

brainstem function

about 26 pathways to the spinal cord originate in various brainstem locations
- send info ab to posture and balance from the brainstem to the spinal cord, and control the autonomic nervous system
unlike the skilled limb and rigid movements organized by the neural cortex, those produced by the brainstem tend to be whole-body movements
other brainstem functions: controlling movement used in eating, drinking, sexual behavior, posture (ability to stand upright), make coordinated movements of the limbs for swimming an walking, movements used in grooming and making nests

How well did you know this?

Not at all

Perfectly

Hess 1957 brainstem

* developed the technique of implanting and cementing electrodes into the brain of cats and other animals * When he stimulated the brainstem of a freely moving animal, he was able to elicit almost every innate movement that an animal of that species might make * emotional behavior could also be modulated

grooming

* particularly complex movement pattern coordinated mainly by the brainstem * When grooming, a cat sits back on its haunches, licks its paws, wipes its nose with its paws, wipes its paws across its face, and finally, turns to lick the fur on its body * always performed in the same order

basal ganglia

* collection of subcortical nuclei in the forebrain * connect the motor cortex with the midbrain and connect the sensory regions of the neocortex with the motor cortex * lesion studies show how relevant are the basal ganglia in the control of movement

basal ganglia recieve inputs from main sources:

1. all areas of the neocortex and limbic cortex,including the motor cortex 2. nigrostriatal dopamine pathway extending into the basal ganglia from the substantia nigra, a cluster of darkly pigmented cells in the midbrain

basal ganglia send projections to:

back to both the motor cortex and the substantia nigra

hyperkinetic symptoms

dyskinesias, huntington's disease, tourette's syndrome caudate putamen damage

hypokinetic symptoms

parkinson's disease difficulty making movements basal ganglia inputs damaged

dyskinesias

(hyperkinetic symptoms) * unwanted movements (ie twitching) * involuntary and exaggerated movements * can result as function of lesion to caudate putamen cells

huntington's disease

(hyperkinetic symptoms) * characterized by involuntary and exaggerated movements (unwanted ticks and vocalization) * destroys caudate putamen cells

tourette's syndrome

(hyperkinetic symptoms) unwanted tics and vocalizations

parkinson's disease

(hypokinetic symptoms) * characterized by muscle rigidity, and difficulty initiating and performing movements * caused by the loss of dopamine cells from the substantia nigra, and of their input into the basal ganglia via the nigrostriatal pathway

Keel and Ivory 1991 basal ganglia

tried to connect these opposing sets of symptoms (hyper and hypo kinetic) by hypothesizing that the basal ganglia's underlying function is to generate the force required for each movement

How does the basal ganglia modulate movement force? pathways

two pathways: inhibitory and excitatory * converge in an area of the basal ganglia called the internal part of the globus pallidus, GPI → GPI in turn, projects to the thalamus, specifically to the anterior thalamic nucleus → thalamus projects to motor cortex * gpi acts like a volume control, because its output determines whether a movement will be weak or strong

main pathways of basal ganglia process

* If activity in the inhibitory pathway (red) is high: inhibition predominates in the GPi * thalamus excites the cortex, amplifying movement * If activity in the excitatory pathway is high: excitation of the GPi will predominate * inhibit the thalamus, reducing input to the cortex and decreasing movement force

cerebellum

motor system component that participates in acquiring and maintaining motor skills

flocullar lobe

(cerebellum) * receives projections from vestibular system * controls balance * many projections go to spinal cord and motor nuclei that control eye movements

medial areas of cerebellum

associated with face and body's midline

tumors/damage to medial areas of cerebellum

* disrupt balance, eye movements, upright posture and walking * but do not substantially disrupt other movements such as reaching, grasping and using the fingers.

lateral parts of cerebellar hemisphere

associated with movements of limbs, hands, feet, and digits

tumors/damage to lateral parts of cerebellar hemisphere

disrupt arm, hand and finger movements far more than movements of the body's trunk

cerebellum's function in movements

1. movement timing 2. movement accuracy 3. seamless combination of movements * coupling movements

corticospinal tracts sends projects descend from originate

* neocortex sends major projections to the brainstem through the corticobulbar tracts and to the spinal cord through the corticospinal tracts * Axons descend from: primary motor cortex (M1 or area four), primary somatosensory cortex (S1), premotor cortex (area 6) * part that descends from S1: terminates in posterior column nuclei of the ascending sensory tracts and modulate sensory signals that are sent to the neocortex * neocortex will then control body movements and modulate sensory information coming in from the body * axons originate: layer five, pyramidal cells of the neocortex * The corticospinal tract axons descend into the brainstem sending collaterals to a few brainstem nuclei and eventually merging on the brainstem ventral surface where they form a large bump on each side of that surface. These bumps known as pyramids, give the corticospinal tracts their alternative name, the pyramidal tracts.

lateral corticospinal tract

* fibers that cross to the opposite side of the brainstem, descend the spinal cord in a lateral location * sends messages to the limbs * axons connect mainly with the lateral motor neurons

anterior corticospinal tract

* fibers that remain on the original side of the brainstem, continue down the spinal cord in an anterior location * sends messages to the trunk * connect mainly to the medial motor neurons

where do corticobulbar and corticospinal tract originate?

The corticobulbar and corticospinal tract axons originate in layer five, pyramidal cells of the neocortex

spinal motor neurons and interneurons

spinal motor neurons and inter neurons are also arranged as a homunculus

lateral motor neurons

project to muscle that control the fingers and hands

interior motor neurons

project to muscles that control the arms and shoulders

most medial motor neurons

project to muscles that control the trunk

evidence suggests that the primary motor cortex is organized on the basis of

specific movements

movement sequences are organized by neurons in the

premotor cortex

the planning of motor movements seems to be the primary responsibility of neural circuits in the

prefrontal cortex

disruption of movement sequences, in the absence of muscle weakness, would follow lesions of the:

premotor cortex

neurons that respond both when the subject performs an action and when the subject observes the action being performed are called ___ neurons

mirror

a patient who has difficulty with balance, posture, and coordination would MOST likely have a lesion in the:

brainstem motor areas

huntington's disease is a genetic disorder resulting from degeneration of

caudate putamen cells

the basal ganglia recieve neural inputs from two main sources. these sources are the:

neocortex and substantia nigra

parkinson's disease is caused by a loss of neurons that release the neurotransmitter:

dopamine

the degenerative disorder associated with msuclar rigidity and difficulty initiating and performing movements is called

parkinson's disease

the contribution of the cerebellum to the control of movement is

fine-tuning of timing and accuracy

difficulty holding a pen to write would MOST likely result from damage to the

lateral corticospinal tract

difficulty maintaining proper posture and balance would MOST likely result from damage to the

anterior corticospinal tract

axons of the __ motor pathway cross over to the opposite side of the spinal cord at the level of the pyramids of the brainstem

lateral corticospinal

specifies movement goals and sends sensory information from vision, touch and hearing into the frontal regions via multiple routes

posterior cortex

On instructions from the posterior cortex, the PFC, prefrontal cortex, generates plans for movements that it passes along to the premotor and motor cortex

prefrontal cortex

* immediately anterior to M1 * houses a movement repertoire, its own lexicon, that, among other things, recognizes others' movements and selects similar or different actions

premotor cortex

more elementary movements than premotor lexicon, including hand and mouth movements

primary motor cortex (MI) / bordmann's area 4

the premotor and motor cortex execute the action

simple movement

the temporal and prefrontal cortices make decisions, and then the premotor and motor cortices execute the appropriate movements.

movement sequence planning required

used cerebral blood flow, serving as an indicator of neural activity, to illustrate neocortical motor control of simpler versus more complex movements

Rolan 1993 hierarchical control of movement in brain

* Because the body is symmetrical, each hemisphere contains an almost mirror image representation of this homunculus. * located a secondary homunculus in the supplementary motor cortex * motor homunculus is upside-down relative to the actual body, with the feet located dorsally within the central fissure and head located ventrally, just above the lateral fissure * the arrangement of body parts is somewhat different from that of the real body * There may be as many as 10 homunculi within the motor and premotor cortices, and parts of the homunculi are arranged as simply as Penfield sketched them

motor homunculus (Penfield 1950s)

* used trains of electrical stimulation of 0.5 seconds in conscious monkeys * found that stimulating elicits action that he calls ethological categories of movement * each region represents three types of organization: * the body part to be moved * the spatial location to which the movement is directed * the movement's function * shows that many cortical maps of the body exist, but each map represents a different action: the part of space in which an action is to take place and that action's intended function * but certain movement types, for example reaching, cluster together relative to the partof motor cortex from which they are elicited * graziano's topography is consistent with Penfield's map and with the idea that whole body movements are represented in the premotor cortex and more discrete movements in the motor cortex

Graziano (2009)

* motor cortex is not the only region from which movements can be evoked * Similar functional movements can be elicited by electrically stimulating the parietal cortex * parietal topography mirrors the motor homunculus * ex: to guide reaching to a target, the visual cortex has to identify both the location of an object and the object itself. Based on information about the object location, the visual cortex instructs the parietal arm region about the object's location and the hand region about how to shape the digits to grasp the object. These parietal regions represent the sensory receptors on the body that will activated when the object is contacted. The reach and grasp regions of the parietal cortex then connect to reach and grasp regions of the motor cortex that will produce the movement over descending pathways to the spinal cord. * Similarly various combination of activity in parietal to motor cortex pathways underlie the complexity of our movements

parietal cortex Kaas 2013 and ex

repertoire of movements categories in the cortex * other support: most primate species use this same grip pattern and second, that people who have incurred small lesions of the motor cortex around the thumb region of the homunculus, have weaknesses not only in the thumb but in the other fingers and in the arm as well * suggested to Schiebe rthat the lesion impair not the hand or individual digit muscle but rather the coordinated action of reaching for and grasping an object * After incurring a lesion in which the pincer grip is lost,a person is likely to substitute any movement. A whole hand grip. The premotor cortex and the primary motor cortex share a common movement lexicon. And the repertoire available to the premotor cortex,is just more complex than that of M1.

lexicon and other support

cells in primary premotor cortex fire when an individual observes a specific action taken by another individual

mirror system neurons

transitive responding to a wide range of actions that might be used to obtain a goal

(human) core mirror system

responds to intransitive actions, movement in which a goal is not present * flexible properties of mirror neurons underlie our inner ability to imagine movements, the ability to understand the actions of others * we understand our own actions and those of others by internally replicating the movements * Our cognitive understanding of an action is embodied in the neural system that produce that action

distributed mirror neuron system

* about 26 pathways to the spinal cord * send information pertaining to posture and balance from the brainstem to the spinal cord, and control the autonomic nervous system * unlike the skilled limb and rigid movements organized by the neural cortex, those produced by the brainstem tend to be whole body movements * other functions: controlling movement used in eating, drinking, sexual behavior, posture (ability to stand upright), make coordinated movements of the limbs for swimming an walking, movements used in grooming and making nests

brainstem motor control

grooming

basal ganglia

basal ganglia recieve inputs from main sources:

back to both the motor cortex and the substantia nigra

basal ganglia send projections to:

dyskinesias, huntington's disease, tourette's syndrome

hyperkinetic symptoms

parkinson's disease type

hypokinetic symptoms

(hyperkinetic symptoms) * unwanted movements (ie twitching) * involuntary and exaggerated movements * can result as function of lesion to caudate and putamen cells

dyskinesias

(hyperkinetic symptoms) characterized by involuntary and exaggerated movements (unwanted ticks and vocalization)

huntington's disease

(hyperkinetic symptoms) unwanted tics and vocalizations

tourette's syndrome

parkinson's disease

How does the basal ganglia modulate movement force?

motor system component that participates in acquiring and maintaining motor skills

cerebellum

(cerebellum) * receives projections from vestibular system * controls balance * many projections go to spinal cord and motor nuclei that control eye movements

flocullar lobe

associated with face and body's midline

medial areas of cerebellum

* disrupt balance, eye movements, upright posture and walking * but do not substantially disrupt other movements such as reaching, grasping and using the fingers.

tumors/damage to medial areas of cerebellum

associated with movements of limbs, hands, feet, and digits

lateral parts of cerebellar hemisphere

disrupt arm, hand and finger movements far more than movements of the body's trunk

tumors/damage to lateral parts of cerebellar hemisphere

1. movement timing 2. movement accuracy 3. seamless combination of movements * coupling movements

cerebellum's function in movements

* neocortex sends major projections to the brainstem through the corticobulbar tracts and to the spinal cord through the corticospinal tracts * Axons from the corticobulbar and corticospinal tract, do not descend only from the primary motor cortex, which we know is also M1 or area four. * Some other axons come from the primary somatosensory cortex, S1 and others from the premotor cortex, area six. * The part of the corticospinal tract that descends from S1, terminates in posterior column nuclei of the ascending sensory tracts and modulate sensory signals that are sent to the neocortex. The neocortex will then control body movements and modulate sensory information coming in from the body. * The corticobulbar and corticospinal tract axons originate in layer five, pyramidal cells of the neocortex. * The corticospinal tract axons descend into the brainstem sending collaterals to a few brainstem nuclei and eventually merging on the brainstem ventral surface where they form a large bump on each side of that surface. These bumps known as pyramids, give the corticospinal tracts their alternative name, the pyramidal tracts.

corticospinal tracts

* fibers that cross to the opposite side of the brainstem, descend the spinal cord in a lateral location * sends messages to the limbs * axons connect mainly with the lateral motor neurons

lateral corticospinal tract

* fibers that remain on the original side of the brainstem, continue down the spinal cord in an anterior location * sends messages to the trunk * connect mainly to the medial motor neurons

anterior corticospinal tract

project to muscle that control the fingers and hands