neuropsychology of executive function

what caused brain damage

strokes or traumatic brain injuries

types of strokes

Ischemic stroke: clot occluding the artery

hemorrhage: brain bleed

types of traumatic brain injuries

Contusion: a bruise on the brain caused by direct trauma, often results in bleeding and swelling

concussion: a mild traumatic brain injury that disrupts normal function

chronic traumatic encephalopathy(CTE): a progressive, degenerative brain disease linked to repetitive head injuries, especially concussions

frontal lobe syndrome

Clinical observations of patients with frontal lobe injuries report a wide variety of deficits that are hard to classify into a single symptom, so they are loosesly defined as frontal lobe syndrome

clinical observations of executive deficits after PFC injury

• can’t follow instructions or generate motor responses

• attentional neglect- similar to parietal lesion (sometimes unilateral sensory neglect)

• perseveration - abnormal repetition of specific behavior, can’t flexibly adjust behavior when required to do so. (Note that this can happen without frontal lobe injury)

• utilization behavior - using the objects place in front of you

examples of neuropsychology tests on patients with brain injuries

• WAIS IQ test

• orientation in time and space (Benton)

• short-term and long-term memory

  • Wechsler memory scale

  • Rey auditory-verbal learning test

• speech language

  • aphasia

  • verbal fluency

• visual perception

  • facial recognition

  • copy figure

  • picture naming

• executive function

  • wisconsin card sorting

  • trail making

  • stroop (less often)

Why are cognitive psychology tasks in patients with brain lesions particularly useful?

allows to test several questions:

• is a region necessary for a particular function

• identify the causal effects of brain functions

• Study the behavioral function of small brain regions that are otherwise hard to study with neuroimaging

why was the prefrontal cortex not “necessary” for WM delay task performance?

compensation from parietal regions

Effect of parietal cortex lesions on WM delay task perfromace?

seemed to have a higher impact on WM task performance in comparison to prefrontal cortex lesions

• at least for the spatial WM task

what is voxel wise lesion symptom mapping?

• for every voxel, classify the patients into a group with a lesion and a group without a lesion

• compare the behavior between these two groups, and assign the test statistic to the voxel

• the test statistic will have a p-value associated with it. → How likely having a lesion in this voxel will impair behavior

what are the processes involved for the trail making test

• attention

• action selection

• short-term memory

wisconsin card sorting task

• Preservative error is the most interesting dependent measure

  • Patients can’t adjust the sorting strategy when given feedback

• a measure of cognitive flexibility

controlled oral word association test

When given a letter, the patients need to generate as many words as possible that start with this letter within one minute

• not so sure if this is an executive function task

iowa gambling task

How often subjects choose the advantageous decks over the disadvantageous decks