Problem 8

Question 1

Reverse engineering

Lesion studies

Answer 1

Refers to a process where one attempts to infer the function of a brain region by observing what the rest of the cognitive system can + can’t do when that brain region is removed

Question 2

Transcranial magnetic stimulation

TMS

Answer 2

Refers to a non-invasive stimulation of the brain that is caused by a rapidly changing electrical current in a coil held over the scalp

Question 3

Transcranial direct current stimulation

tDCS

Answer 3

Refers to non-invasive stimulation of the brain caused by passing a weak electrical current through it

–> can be used to boost cognitive function (e.g. rehabilitation)

Question 4

Single dissociation

Answer 4

Being impaired in performing one task but not in another related one

–> being impaired in both tasks but significantly worse in one is a strong single dissociation

Question 5

Provide explanations for single dissociation.

Answer 5

1. each task uses different cognitive processes
2. Task-resource artifact
   - -> they both use the same cognitive resources but one task utilizes more of this resource
3. Task-demand artifact
   - -> patient performs one of the tasks sub optimally because he misunderstood the instructions

Question 6

Double dissociation

Answer 6

Occurs when two related mental processes are shown to function independently of each other

–> most powerful way of discounting a task-resource artifact

THUS: provides evidence that 2 functions are separate/independent

Question 7

The fractionation assumption

Answer 7

Assumes that brain damage can produce selective cognitive lesions

Question 8

Transparency assumption

Answer 8

Assumes that lesions affect one or more components within the pre-existing cognitive system

BUT: lesions do not result in a completely new cognitive system

Question 9

Universality assumption

Answer 9

Suggests that all cognitive systems are basically identical

Question 10

Why are single case studies said to be the only acceptable method in cognitive neuropsychology ?

Answer 10

Because, averaging across participants may not be possible/wise as

1. differences in observed performance may be attributable to differences in lesion
2. determining whether the lesion is in the cognitive system can only be determined by observing each case in turn

Question 11

Name the most common objections against the use of single-case studies ?

Answer 11

One cannot create a theory based on observations from only a single case

Question 12

Name the grouping principles by which patients should be grouped in oder to associate lesion sites with deficits ?

Answer 12

1. Grouping by syndrome
   - -> best for understanding the neural correlates of a given disease pathology
2. Grouping by cognitive symptom
3. Grouping by anatomical lesion

Question 13

There are various methods for producing experimental lesions in animals.

Name them.

Answer 13

1. Aspiration
   - -> suction device
2. Transection
   - -> cutting off discrete white matter bundles
3. Neurochemical lesions
4. Reversible lesions
   - -> temporary

Question 14

Unilateral spatial neglect

Answer 14

Occurs when the brains attention network is damaged in only one hemisphere

–> most persistent + severe effects occur from right HP damage

Question 15

Ipsilesional

Answer 15

Attention bias in the direction of the lesion

–> disregarding everything to the left if the patient has lesion on right HP

Question 16

How does neglect affect the people suffering from it ?

Answer 16

1. Objects present in the visual world
2. Imagination
3. Memory

–> they do not actually lack the memory but their attention to parts of the recalled images is biased

Question 17

How can we distinguish neglect from blindness in the contralateral visual HP ?

Answer 17

Neglect patients do detect stimuli normally when they are salient + presented in isolation

e.g. flashes of light, wiggling of fingers

Question 18

Extinction

Answer 18

Refers to the failure to perceive or act on stimuli contralateral to the lesion (contralesional stimuli) when presented simultaneously with a stimulus ipsilateral to the lesion (ipsilesional stimulus)

–> extinction does not occur when stimuli are presented one at a time to each hemifield

Question 19

Balints syndrome

Answer 19

Demonstrates 3 deficits

1. Simultanagnosia
   - -> difficulty perceiving the visual field as a whole scene
2. Ocular apraxia
   - -> difficulty making eye movements to scan the visual field/voluntarily moving eyes
3. Optic ataxia
   - -> difficulty moving the hand to a specific object

THUS: disturbance in perception

Question 20

Association

Answer 20

Suggests that the behavioral/cognitive phenomena in question are a manifestation of one underlying process

–> consistent co-occurence of 2 or more impairments

Question 21

Commissurotomy/

Split brain surgery

Answer 21

Involves the cutting of the corpus callosum

–> supposed to stop seizures from spreading to both HPs

Question 22

Sodium amobarbital test

SAT

Answer 22

Refers to a surgery for the relief of seizures that involves the removal of the cortex region that has been declared the origin of the patients seizures

Question 23

Testing procedure of the SAT

Answer 23

1. Barbiturate sodium abobarbital is injected into the internal carotid artery
2. It then enters the cerebral circulation + passes into the ipsilateral middle cerebral artery
3. This HP is then anesthetized
4. Before the drug is injected the patient is instructed to extend the arms + wiggle toes
5. After drug injection he suffers a hemiparesis
6. Various tests can be conducted

Question 24

Hemiparisis

Answer 24

Extreme weakness of one side of the body

Question 25

Neurochemical lesions

Answer 25

Using chemicals to alter the normal functioning of neurons

–> reversible effects: as long as the drug os active, the exposed neurons do not function, when the drug wears off the function will gradually return

BUT: not all are reversible

Question 26

Lesions studies in humans

Answer 26

Works by either

1. picking a population with similar anatomical lesions
2. Assembling a population with a similar behavioral deficit