lecture 5 - perturbation methods

Question 1

accidental perturbations

alzheimer’s

Answer 1

tangles & plaques in limbic and temporoparietal cortex

Question 2

accidental perturbations

parkinson’s

Answer 2

loss of dopaminergic neurons

Question 3

accidental perturbations

huntington’s

Answer 3

atrophy of interneurons in caudate and putamen of the basal ganglia

Question 4

accidental perturbations

picks

Answer 4

frontotemporal atrophy

Question 5

accidental perturbations

disadvantages of accidental perturbations

Answer 5

not the most useful in making inferences about healthy human brain localization because atrophy likely to be widespread

Question 6

accidental perturbations

chronic traumatic encephalopathy (CTE)

Answer 6

atrphy related to continued head trauma

Question 7

brain lesions

brain lesions advantages

Answer 7

• shows localized functions
• can ask what consequences/changes are

Question 8

brain lesions

surgical extirpation

Answer 8

cut out tissue of interest - irreversible

Question 9

brain lesions

electrical lesions

Answer 9

heat tisse with strong electric current - irreversible

Question 10

brain lesions

chemical lesions

Answer 10

injection of neurotoxins
- irreversible - kill neurons (ibotenic acid)
- reversible - temporary dysfunction (lidocaine)

Question 11

brain lesions

cryogenic lesions

Answer 11

freeze a section of tissue - reversible

Question 12

brain lesions

assumptions

Answer 12

1. brain injury is eliminative, damage causes dsyfunction
2. cognitive capacities can be analyzed into elemental (low-level) processes that underlie the capacity

Question 13

brain lesions

single vs double dissociation

Answer 13

brain lesion impairs one function but not another
vs
one lesion impairs A not B, other impairs B not A

Question 14

brain lesions

translation

concerns

Answer 14

are animals/patients good models/telling of healthy human brain function?

Question 15

brain lesions

specificity

concerns

Answer 15

do we know the precise boundaries of the lesions?

Question 16

brain lesions

compensatory mechanisms?

concerns

Answer 16

has damage caused reorganization/plasticity?

Question 17

brain lesions

behavioral complexity

concerns

Answer 17

are complex functions precisely located/ tied to one area?

Question 18

electrical perturbation

cortical stimulation

Fritsch & Hitzig

Answer 18

electrode implants on surface of brain (cortex)

Question 19

electrical perturbation

optogenetics

Answer 19

opsin inserted through genetic modification of cell populations, activation/deactivation of neurons w/ light

Question 20

electrical perturbation

deep brain stimulation

Answer 20

electrode insertion into deep brain tissue
ex: sub thalamus nucleus insertion to treat Parkinson’s

Question 21

non-invasive methods

transcranial magnetic stimulation (TMS)

Answer 21

delivering magnetic pulse through & across skull (superficial cortex) to disrupt neural activity

Question 22

non-invasive methods

observable effects of TMS

Answer 22

directed @ motor cortex, elicits observable muscle twitch or “motor evoked potential”

Question 23

non-invasive methods

online TMS

temporary lesion

Answer 23

establish timing of particular cognitive process and disrupt it
- one well timed pulse, double pulse, or short train of pulses

Question 24

non-invasive methods

offline TMS

Answer 24

extended electrical effects with extended stimulation
- 1-10 min period @ 1Hz pulse rate

Question 25

# non-invasive methods TMS experimental considerations/disadv.

Answer 25

1. inability to penetrate too deeply, limited to cerebral cortex 2. possible downstream effects b/c of interconnectivity 3. can be uncomfortable

Question 26

# chemical perturbation - neuropsychpharm drug alteration

Answer 26

exogenous compounds bind to postsynaptic receptors

Question 27

# chemical perturbation - neuropsychpharm agonists

Answer 27

similar structures as NTs, mimics NT action

Question 28

# chemical perturbation - neuropsychpharm antagonists

Answer 28

block or attenuate neurotransmission

Question 29

# genetic perturbations knockout technique

Answer 29

genetic engineering to temporary turn off (reversible) or delete (irreversible) specific gene(s) examines consequences of lack of gene coding for particular protein

Question 30

# genetic perturbation example of knockout technique

Answer 30

turn off gene that expresses transmembrane receptor like NMDA (glutamate)