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Brain and Perception Revision > Lecture 4 Introduction to human neuropsychology, what does the prefrontal cortex do? > Flashcards

Lecture 4 Introduction to human neuropsychology, what does the prefrontal cortex do? Flashcards

1
Q

What is the frontal cortex made up of?

A

Prefrontal cortex + motor cortex

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2
Q

What is the prefrontal cortex made up of ?

A

Lateral PFC and Medial PFC

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3
Q

Grey matter in humans PFC compared to chimpanzees and macaques

A

.2x greater than in chimpanzees and 1.9x greater than macaques

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4
Q

White matter tracts in humans compared to chimpanzees

A

1.7x denser subcortical connection in humans compared to chimpanzees

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5
Q

Size of prefrontal cortex in human brain

A

Volume = 512 cm3
21% of brain
9x larger than visual areas
12x larger than motor areas

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6
Q

Size of prefrontal cortex in the brains of chimpanzees

A

Volume = 134 cm3
17% of brain
3x larger than visual areas
3x larger than motor areas

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7
Q

Size of prefrontal cortex in macaque monkeys

A

Volume = 34.3 cm3
13% of brain
The same size as visual and motor areas

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8
Q

Synaptogenesis:

A

forming new synaptic connections

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9
Q

Dendritic arborization

A

More tree-like structure in dendrites

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10
Q

Pros of using single case studies:

A

Proof of principle
Ethical

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11
Q

Cons of using single case studies

A

Causality
Non-focal

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12
Q

Non-human models commonly used in brain research

A
  • Drosophila (fruit fly) models. 9 Nobel Prizes
  • Rodent models
  • Non-Human primate models
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13
Q

Pros of using non-human models to study the brain

A

Full experimental control
Directness

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14
Q

Cons of using non-human models to study the brain

A

Non-human
Ethics

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15
Q

Pros of asking patients who suffering brain difficulties to report their experiences:

A

View from the inside
Practicality

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16
Q

Cons of asking patients who suffering brain difficulties to report their experiences:

A

Lack of control
Subjectivity

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17
Q

Key info on how the Tower of London task works

A

Participants need to re-arrange the bottom display (from A) to look like the top display (to get to B)
Move discs varying in size from small to large across 3 pegs to build a designated tower in the fewest number of tries as possible

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18
Q

Independent variable: Tower of London task

A

Number of moves
Patient group

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19
Q

Dependent variable: Tower of London task

A

Accuracy or reaction time

20
Q

Owen et al (1990) Tower of London study

A

Found frontal lobe patients showed impaired planning - requiring significantly more moves to solve the problem compared to controls
Evidence for frontal lobe involvement in planning

21
Q

nitschke et al (2017, HBM) studies in tower of london task

A

Did a review of 6 studies on frontal lobe patients and planning
Found majority of studies show impaired accuracy compared to controls
No evidence that left hemisphere lesions were more disruptive than right hemisphere lesions

22
Q

Pros of patient/control studies

A

Multiple patients
Practicality

23
Q

Cons of patient/control studies

A

Classification issues
Lack of control

24
Q

Owen et al (1995b) study Tower of London

A

examined planning performance in patients with lesions to the temporal cortex/medial temporal lobe

25
Owen et al (1995b) study findings
Patients with lesions to the temporal lobe or amygdala/hippocampus were not significantly impaired on this task (TOL)
26
What FMRI scans can tell us about damage to prefrontal cortex:
Lesions to the frontal cortex not only damage this region but also damage white matter connections
27
Van horn et al (2012)
Estimates Gage lost 10% of white connections
28
Why MRI scans can be useful
Help understand what the frontal lobes are doing during planning
29
How FMRI shows brain in action
- Brain needs oxygen - Increase in blood flow so more oxygenated blood changing the ratio of oxygenated and deoxygenated blood Increased “Magnetic Signal” after neural activity
30
What are block designs?
- We examine whether there are changes in BOLD signal when people are performing tasks in the scanner - Have two tasks: the main task A and Task B the control
31
Blood oxygenation-level dependent (BOLD) signal meaning
Changes in the ratio of oxygenated and deoxygenated haemoglobin
32
What makes a good control task?
- Same perceptual experience - Same motor demands - Same emotional state
33
Cognitive subtraction meaning
Subtracting the two images from the FMRI scan will reveal which parts of the brain have higher activity/blood flow in task A compared to task B
34
FMRIS studies of the Tower of London (Fallon et al, 2013)
The dorsolateral prefrontal cortex is recruited during planning, as well as other brain areas The scan image will show all the brian parts that increased BOLD signal compared to control, mainly lateral prefrontal cortex
35
Deactivation: "Default mode"
a set of brain regions that decrease their activity in task performance When the brain is consumed by processing it's own world - subjective
36
Need for balance in brain regions
Between 'executive' dorsolateral prefrontal cortex and "subjective" medial prefrontal cortex
37
Spreng and Schacter (2012) Tower of London task study
Used fMRI Older adults showed impaired accuracy Older adults don't show expected decreases in medial prefrontal cortex during planning
38
Key takehomes from fMRI results
The occipital lobe and the parietal lobe also show increases BOLD signal in planning Decreases in medial prefrontal cortex Prefrontal involvement in planning seems to involve both increases and decreases
39
Pros of using fMRI studies
- Reveals brain networks - precision
40
Cons of using fMRI studies
Practicality Causality
41
Non-invasive brain stimulation: How necessary is the frontal cortex for planning performance?
- Lesion evidence implies that prefrontal cortex is necessary for normal planning performance - Neuroimaging suggests both frontal and non-frontal regions involved in planning - Also increases and decreases in activity in frontal lobs
42
Non-invasive brain stimulation: Transcranial magnetic stimulation (TMS)
Can isolate the effects after stimulation Can be excitatory or inhibitory depending on stimulation parameters
43
Van de Heuvel et al (2013) TMS study
used inhibitory TMS on the left dorsolateral prefrontal cortex prior to planning:
44
Van de Heuvel et al (2013) TMS study, results
- Inhibition of left dorsolateral prefrontal cortex impairs planning performance - After TMS inhibition, decreased BOLD signal was found in left premotor cortex, left anterior prefrontal cortex and praecuneus
45
Pros of Transcranial magnetic stimulation (TMS)
Causality Focal
46

Brain and Perception Revision (11 decks)

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