Chapter 9 Flashcards
1
Q
A
2
Q
motor system process
list the pieces
A
3
Q
posterior cortex
A
- 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
4
Q
prefrontal cortex
A
On instructions from the posterior cortex, the PFC, prefrontal cortex, generates plans for movements that it passes along to the premotor and motor cortex
5
Q
premotor cortex
A
- immediately anterior to M1
- houses a movement repertoire, its own lexicon, that:
- recognizes others’ movements
- selects similar or different actions
- organizes whole body movements
6
Q
primary motor cortex (MI) / bordmann’s area 4
A
more elementary movements than premotor lexicon, including hand and mouth movements
motor cortex calculates both the direction and the distance of movements
7
Q
simple movement
A
If a movement is relatively simple, then the premotor and motor cortex execute the action.
8
Q
movement sequence
A
If planning is required, the temporal and prefrontal cortices make decisions, and then the premotor and motor cortices execute the appropriate movements.
9
Q
Rolan 1993
hierarchical control of movement in brain
A
- used cerebral blood flow, serving as an indicator of neural activity, to illustrate neocortical motor control of simpler versus more complex movements
10
Q
motor homunculus (Penfield 1950s)
A
- 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
11
Q
Graziano (2009)
A
- 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
- each region represents three types of organization:
- found that stimulating elicits action that he calls ethological categories of movement
- 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
12
Q
parietal cortex
Kaas 2013
A
- 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
13
Q
parietal cortex Kaas ex
A
- 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
14
Q
lexicon
and other support
A
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.
- 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
15
Q
Brinkman 1984
premotor cortex
A
- 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
16
Q
Fukuda 1981
learning to move
A
- 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.
17
Q
Evarts 1968
motor cortex cells
A
- 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
- 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
18
Q
Gerogopoulos (1999)
monkeys pt 2
A
- 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
19
Q
Mita 2001
monkeys and mirrors
A
- 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
20
Q
mirror system neurons
A
- 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
21
Q
(human) core mirror system
A
transitive (respond to actions that obtain goal objects)
more broadly tuned
22
Q
distributed mirror neuron system
A
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
23
Q
Salatin 2014
mirror neuron system
A
- 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
24
Q
brainstem function
A
- 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
25
Q
Hess 1957
brainstem
A
- 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
26
Q
grooming
A
- 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
27
Q
basal ganglia
A
- 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
28
Q
A
29
Q
basal ganglia
recieve inputs from main sources:
A
- all areas of the neocortex and limbic cortex,including the motor cortex
- nigrostriatal dopamine pathway extending into the basal ganglia from the substantia nigra, a cluster of darkly pigmented cells in the midbrain
30
Q
basal ganglia
send projections to:
A
back to both the motor cortex and the substantia nigra
31
Q
hyperkinetic symptoms
A
dyskinesias, huntington’s disease, tourette’s syndrome
caudate putamen damage
32
Q
hypokinetic symptoms
A
parkinson’s disease
difficulty making movements
basal ganglia inputs damaged
33
Q
dyskinesias
A
(hyperkinetic symptoms)
- unwanted movements (ie twitching)
- involuntary and exaggerated movements
- can result as function of lesion to caudate putamen cells
34
Q
huntington’s disease
A
(hyperkinetic symptoms)
- characterized by involuntary and exaggerated movements (unwanted ticks and vocalization)
- destroys caudate putamen cells
35
Q
tourette’s syndrome
A
(hyperkinetic symptoms)
unwanted tics and vocalizations
36
Q
parkinson’s disease
A
(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
37
Q
Keel and Ivory 1991
basal ganglia
A
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
38
Q
How does the basal ganglia modulate movement force?
pathways
A
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
39
Q
main pathways of basal ganglia
process
A
- 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
40
Q
cerebellum
A
motor system component that participates in acquiring and maintaining motor skills
41
Q
A
42
Q
flocullar lobe
A
(cerebellum)
- receives projections from vestibular system
- controls balance
- many projections go to spinal cord and motor nuclei that control eye movements
43
Q
medial areas of cerebellum
A
associated with face and body’s midline
44
Q
tumors/damage to medial areas of cerebellum
A
- disrupt balance, eye movements, upright posture and walking
- but do not substantially disrupt other movements such as reaching, grasping and using the fingers.
45
Q
lateral parts of cerebellar hemisphere
A
associated with movements of limbs, hands, feet, and digits
46
Q
tumors/damage to lateral parts of cerebellar hemisphere
A
disrupt arm, hand and finger movements far more than movements of the body’s trunk
48
Q
corticospinal tracts
sends projects
descend from
originate
A
- 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
- 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
- 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.
49
Q
A
54
Q
lateral motor neurons
A
project to muscle that control the fingers and hands
55
Q
interior motor neurons
A
project to muscles that control the arms and shoulders
78
Q
- 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
A
motor homunculus (Penfield 1950s)
79
Q
- 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
- each region represents three types of organization:
- found that stimulating elicits action that he calls ethological categories of movement
- 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
A
Graziano (2009)
82
Q
cells in primary premotor cortex fire when an individual observes a specific action taken by another individual
A
mirror system neurons
87
Q
- 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
A
basal ganglia
96
Q
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
A
How does the basal ganglia modulate movement force?
104
Q
- 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.
A
corticospinal tracts
107
Q
project to muscle that control the fingers and hands
A
lateral motor neurons
108
Q
project to muscles that control the arms and shoulders
A
interior motor neurons
110
Q
initiating a motor sequence
A
111
Q
basal ganglia connections
A
114
Q
interneurons, motor neurons, and muscles
A
115
Q
A
