Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NEURAL BASIS OF VISION > Cortical Sensorimotor Systems > Flashcards

Cortical Sensorimotor Systems Flashcards

1
Q

how is the cerebral cortex organised?

A

through hierarchal sensory-motor organisation, that focuses on planning and programming in the premotor and motor complex, that provides sensory feedback into cortical areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

two main areas of the cerebral cortex

A

basal ganglia and cerebellum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

basal ganglia

A

initiates movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

cerebellum

A

is important for fine-motor control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how is the cerebral cortex divided?

A

into four main lobes (motor regions within the frontal lobe)

forms the outer surface of the forebrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

layers of the cerebral cortex

A

has 6 distinct layers of laminae which define different regions of the cortex by their different cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

example of layer-specific inputs and outputs of the cerebral cortex

A

5 and 6 are both involved in sending outputs to the muscles and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

brodmann (1868-1918)

A

defined 52 areas of the cortex based on their distinct laminae profiles, to identify different relevant functions of different anatomic cortical areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where is the primary cortex located?

A

the frontal lobe, and this is one of the primary areas involved in motor function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does the primary motor cortex (M1/BA4) contain?

A

betz cells in layer 5, which project from motor cortex to the spinal tract

95% of these cells instead reach spinal interneurons and project to the brainstem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the purpose of betz cells along the corticospinal tract?

A

initiate, regulate, and control voluntary movement by innervating alpha/gamma motor neurones in the spinal cord to cause muscle contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where does the corticospinal tract cross?

A

at the medulla, hence limb movements are controlled by contralateral M1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how can M1 be mapped?

A

by somatotopic representations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

somatotopic representations

A

different parts of the motor cortex send motor signals to different parts of the human body

  • related to how much fine-motor control is required
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

penfield (1940)

A

discovered electrical stimulation causes simple movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what do cortical motor maps reflect?

A

sensory-motor specialisation, seen in changes based on what is used most

  • humans have big representations of hand/face as we have most fine-motor control of these
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

overlap between cortical motor maps

A

between these areas based on how much the muscles work together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what was initially believed the motor cortex represents?

A

simple contractions of contralateral muscles, seen in brief micro-stimulation of 50ms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

sustained stimulation longer than 500ms results in…

A

complex goal-directed actions, such as defence, climbing, and reach-to-grasp in monkeys, but these results have not been shown in humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

precision grip in M1…

A

requires more M1 activity than power grip, but muscle activity remains the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

motor lesions result in…

A

loss of individuated fine movements, and result in ‘gross’ trunk movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are frontal eye fields connected to?

A

the superior colliculus, which is a somatotopic area in the frontal lobe important for volitional control of eye movements

23
Q

what is FEF connected to?

A

the occipital cortex and frontal regions important for decision making

24
Q

why are there dense connections between sensory motor areas and M1?

A

secondary sensory motor areas are involved in executing actions vs M1 sends out motor commands

25
Q

secondary motor areas

A

supplementary motor area
premotor cortex
- dorsal PM
- ventral PM
posterior parietal cortex

26
Q

what does PPC link?

A

frontal cortex decision-making with premotor planning areas, as it receives information from sensory regions

27
Q

what is PPC important for?

A

determining potential actions given the environment

  • the frontal cortex then decides which action to perform, and secondary areas plan for these
28
Q

SMA regions

A

SMA proper learning
preSMA for execution

29
Q

what is SMA involved in?

A

postural stability and planning and executing complex sequential movements

30
Q

what does SMA initiate?

A

internally generated movements, that are not stimulus-driven

31
Q

what is PMd important in?

A

preparation of movement and learning conditional actions in response to external cues, e.g., red traffic light – foot on brake

32
Q

what is PMv important in?

A

sensory guidance of movement, such as responding to tactile, visual, and auditory stimuli

involved in visuomotor control during grasping and contains mirror neurones

33
Q

mirror neurons

A

were first reported in the PMC

these show similar activity when performing and observing the same action – important for observation learning and understanding intention

34
Q

neuroplasticity

A

ability of the brain to form and reorganise synaptic connections, in response to learning, experience, or following injury. This can occur in all brain areas, but clear in M1.

35
Q

rapid changes in the somatosensory or somatotopic maps after change in inputs:

A
  • training expands map
  • denervation/amputation reduces the map
  • co-activation fuses the maps
36
Q

how do changes in maps reflect neuroplasticity?

A
  • long-term changes in functional connectivity
  • branching of dendritic connections
  • neurons compete for space in the cortex
37
Q

what is synapse efficacy an example of?

A

learning-based neural changes, as synapses enable neurons to communicate with each other

38
Q

presynaptic

A

increase vesicle volume, availability of vesicles, and increase release probabilitysy

39
Q

synaptic cleft

A

reduce reuptake mechanisms and gap dimensions

40
Q

postsynaptic

A

increase receptor density and area

41
Q

growth

A

make new synapses

42
Q

what causes long-term synaptic changes?

A

specific timed patterns of neuronal activity

43
Q

LTP

A

activity-dependent strengthening of synapses, which produces a long-lasting increase in signal transmission between two neurons

44
Q

LTD

A

activity-dependent reduction in the efficacy of neuronal synapses, producing a long-lasting decrease in signal transmission between two neurons

45
Q

associative LTD induction involves…

A
  1. NMDA channel is normally blocked by Mg+ and concurrent voltage channel drives this out
    a. Achieved by glutamate binding to nearby AMPA receptors
  2. Glutamate binds to NMDA and AMPA receptors
    a. Temporary change in shape of channel which opens it up
    b. Calcium enters through the open, unblocked NMDA channel
  3. Ca+ entry triggers intra-cellular signalling cascade which results in…
    a. Migration of AMPA receptors from intracellular stores to the cell membrane
    b. Synthesis of more AMPA receptors
46
Q

what does increasing AMPA receptors result in?

A

greater communication between neurones due to more output

47
Q

key principles of LTP and importance to learning and memory

A

cooperation

associative

synapse specific

48
Q

cooperation

A

LTP requires simultaneous activation of large number of axons due to large depolarisation

Ensures only events of high significance that activate inputs will result in memory storage

49
Q

associative

A

Pairing weak synaptic input with large depolarisation can cause LTP at synapse

Allows an event with little significance to have meaning, when associated with a significant event

50
Q

synapse specific

A

If particular synapse is not activated, then LTP will not occur even with strong post-synaptic depolarisation

Inputs that convey information not related to an event will not be strengthened in memory

51
Q

where was LTD first identified?

A

hippocampus and believed to be a major component of motor learning in the Cerebellum. Involves decrease in AMPA receptors, however this is not NMDA-dependent

52
Q

how can LTP and LTD-like mechanisms be measured in humans?

A

with TMS by stimulating shallow brain regions as a result of pulses caused by magnetic coils placed on the scalp, which cause muscle contractions.

53
Q
A

NEURAL BASIS OF VISION (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions