Lecture 14 - Prefrontal Cortex

Question 1

Prefrontal cortex

Answer 1

located anterior to precentral sulcus (ant. sulcus to motor cortex)

Question 2

Regions of PFC

Answer 2

dorsolateral PFC (top and to the side)
ventromedial PFC (bottom and central)

Question 3

Dorsolateral PFC function

Answer 3

Connect to premotor cortex and frontal eye fields
-behavioral and movement planning

Connect to lateral parietal cortex

• working memory
• focused attention
• sensory/spatial processing (executive function)

Question 4

Prefrontal loop

Answer 4

For action selection

• Dorsolateral PFC (cortical input)
• anterior caudate (striatum)
• globus pallidus, internal segment; substantia nigra, pars reticulata (pallidum)
• mediodorsal and ventral anterior nuclei (thalamus)
• dorsolateral PFC

Question 5

Ventromedial PFC function

Answer 5

Connect to hypothalamus and brainstem
-regulation of autonomic, visceral responses (like HR)

Connect to ventral striatum (basal ganglia)
-reward and decision-making + value computation
> vmPFC recognizes common value currency across all things and establishes relative value that allows us to compare apples to oranges lesion causes indifferent, inappropriately cheerfulness, lack of distress, worry or anger moral judgement, more activity with “self-focused” thought than “other-focused” thought

Question 6

Limbic loop

Answer 6

Regulation of behavior, moods, and emotion

• Amygdala, hippocampus, orbitofrontal, anterior cingulate, temportal cortex (cortical input)
• ventral striatum (striatum)
• ventral pallidum (pallidum)
• mediodorsal nucleus (thalamus)
• anterior cingulate, ventromedial PFC

Question 7

superior longitudinal fasciculus

Answer 7

connects dorsolateral PFC to lateral parietal regions

Question 8

uncinate fasciculus

Answer 8

connects ventromedial PFC to anterior temporal lobe (hippocampus)

Question 9

Blood supply

Answer 9

vmPFC - Anterior Cerebral Artery (ACA)

dlPFC - Middle Cerebral Artery (MCA)

Question 10

working memory

Answer 10

dlPFC neurons fire during “delay” period (period where you must remember location/information about something)

ex. Monkey shown dish with food, cover for 5 sec (delay), they choose the dish with food

Question 11

Tests of executive function or cognitive control

Answer 11

assess function integrity of PFC

Question 12

Phineas Gage

Answer 12

damage vmPFC but not dlPFC
-loss of impulse control, empathy, guilt
-Iowa gambling task: lesion in vmPFC –> never really learn to stay away from “bad decks”
> issues with unlearning bad “reward”
> deficits integrating reward info with decision making
-still very high IQ and able to process information (dlPFC)

Question 13

Prefrontal lobotomy

Answer 13

Egas Moniz 1930s - Portuguese neurologist
Walter Freeman 1950-1960s - icepick lobodomy

done for psychiatric patients

Question 14

Deep brain stimulation

Answer 14

apply current to vmPFC in efforts to treat depression

Question 15

Pathology

Answer 15

Frontotemporal Dementia (FTD)

• degeneration of anterior brain, particularly PFC
• entire PFC affected

Ischemic Stroke
-ACA or MCA

Subarachnoid Hemorrhage

• rupture of blood vessels (aneurysm)
• common in circle of willis (A comm.)

Tumor

• areas that get tumors more often
• surgical resection still leaves damaged area

Traumatic Brain Injury
-often orbitofrontal cortex (sits on bony plate about eyes and fast decceleration causes brain to ricochet off of skill and shear across bony plate)