Prefrontal Cortex: Cognition, Emotion, Behavior Flashcards
What structures are int he prefrontal cortex
Medial prefrontal cortex
Dorsolateral prefrontal cortex
Orbitofrontal
What structures are in the medial prefrontal cortex
- superior frontal gyri
- cingulate gyrus
What structures are int he dorsolateral prefrontal cortex
- superior frontal gyri
- middle frontal gyri
- inferior frontal gyri
What structure is in the orbitofrontal
Orbital gyri
Gyrus rectus
What does the prefrontal cortex serve
Many “higher functions” due to convergence of input from many cerebral regions
Maintaining focus and effort on one task, related to level of alertness
Sustained attention
What kind of attention is dependent on prefrontal/orbitofrontal cortex and other subcortical and brainstem regions
Sustained attention
Ability to tune-out irrelevant stimuli and to enhance detection and processing of relevant stimuli
Selective attention
What kind of attention is dependent on the prefrontal/orbitofrotnal cortex and input from the parietal lobe
Selective attention
Examples of selective attention
- Visual: where’s Waldo? Or finding family member in a crowd.
- Auditory: listening to a friends voive while tuning out a nearby strangers. Listening to one of several instruments during a song
Switching focus of selective attention between different types of stimuli
Attentions “set-shifting”
Examples of attentional set shifting
Color vs shape of visual object, adult vs child voices in convo, listening to prosody vs semantic aspects of speech.
What is the prefrontal/orbtiofrontal cortex mainly used for
Attentions
Selective attention for visual spatial attention, what lobe?
Superior parietal lobule regulates activity in primary or secondary visual cortex
Top down
Selective attention and visual object information
Similar top down regulation occurs: temporal visual association cortex regulates primary or secondary visual cortex
Selective attention for other types of sensory information
Not well understood, but general principal is sensory association cortex projected to primary sensory cortex and acts to filter our irrelevant info
What is a common test for selective attention or “set shifting”?
Stroop test
What is the stroop test
Tests selective attention or “set shifting” by having a color and meaning of word mismatched
What is the set shifting in stroops test dependent on
Dorsolateral prefrontal cortex and anteiror cingulate gyrus cortex
Damage to dorsolateral prefrontal cortex and the anterior cingulate cortex
Impairs both maintaining focus on a set and set shifting
Areas of brain responsible for set shifting
Dorsolateral prefontal cortex and anteiror cingulate cortex
What does switching response criteria in set shifting depend on
Orbitofrontal cortex
Damage to the orbitofrontal cortex and set shifting
Impairs set shifting but patient may still be able to maintain focus on initial set
Ability to hold information in mind during use for seconds to hours
Short term or working memory
Accuracy of recall in short term or working memory
Accuracy of recalled information decreases as delay length increases: delay-dependent memory
What is short term memory mediated by
Prefrontal cortex, mainly dorsolateral prefrontal cortex
Spatial working memory localization
Dorsal to inferior frontal sulcus
Object working memory localization
Ventral to inferior frontal sulcus
Lab test for working memory (short term)
Delayed non-match to sample test
Basically a matching game
N-test
Stream of one letter or number appearing at a time, changing every 1-2 seconds, subject responds by noting if current letter or number matches 2 samples ago (2-back) or is a mismatch
-difficulty can be increases
Maintaining focus and effort on one task
Sustained attention
What is the cause of sustained attention
NT through diffuse projections though out cerebral cortex and lambic regions, especially to prefrontal cortex. Prefrontal cortex is a major target of ascending NT projections systems, whose cell bodies are in brainstem nuclei or deep subcortical regions in cerebrum
What NT promotes alertness, sustained attention, and selective attention
Locus coeruleus, a major ascending noradrenergic (NE) system
Promotes selective attention to relevant stimuli, especially rewarding stimuli
Ventral Tegmental area, a major ascending dopaminergic system with widespread projections throughout the prefrontal cortex and lambic regions
Where is the ventral tegmental area
In the substantia nigria
Conventional medication of ADD
Ritalin and adderol, they increase action of NE and dopamine
Cholinergic (acetylcholine) neurons
Form multiple subcortical regions have widespread projections targeting cerebral cortex, lambic regions. Enhance both sustained and selective attention
Emotional/motivational/behavioral functions
- motivational level toward specific/all tasks/goals
- impulse control and delayed gratification
- social interactions
- emotional stability and self regulation
- prefrontal regulation of fear/stress
Cognitive/executive functions
Decision making
Assessing whether stimuli are rewarding or aversive, or predict danger or reward, consequences of decisions
Decision making
Phineas gage
- Rail road stake in head
- alert and normal during exam immediately after accident
- head injury not fully closed till several months later
- 1 month later falls into coma, awakes next day unable to raise head from bed
- couple days later: long term memory intact, but impaired at size estimations and counting. Acts childishly and wants to go to childhood home
- reports being pain free and goes home
- cant keep work
Major changes noted in Phineas Gage
- loss of motivation at work, becomes unreliable
- profane and socially inappropriate
- emotionally volatile or agitated
Frontal love release phenomenon
- Behavior is diminished and inappropriate, including towards medical professionals
- infantile reflexes (grasping finger, suckling)
Utilization behavior, aka environmental dependency
Inappropriate use of objects when they suddenly become available, answering questions that are being directed to someone else
A patient repeatedly says the same words, or the same motor responses, or the same choices in a cognitive test, despite these responses now being inappropriate.
Preservation
An impairment in attentional set shifting (failing to shift) is a _________ error
Perseverative error
Patient does not spontaneously produce speech and may be verbally unresponsive to questioning/examination. This deficit is a motivational deficit, not a problem in the language system (not aphasia)
Akinetic mutism
Term derives from lack of ebullient mood/attitude (flat emotion). Lack of spontaneous behavior of any kind, delayed motor/verbal responses. Could contribute to a dx of major depression
Abulia
Extreme forms of abulia and akinetic mutism
Can present as a catatonic state
Vascular territory of prefrontal/orbitofronalt cortex
Branches of ACA
Vascular territories of orbitofrontal cortex
Medially: MCA
Laterally: ACA
When does the prefrontal cortex develop
Not until 20s
What is the last brain region to fully develop
Prefrontal cortex
How does the prefrontal cortex mature
Over production of synapses followed by pruning
Behavioral implications of a developing prefrontal cortex
Gradual maturation of executive and emotional functions: risk/reward assessment, delayed gratification, impulse control, resisting peer pressure
Disorders involving impaired prefrontal development
Autism
Schizophrenia
Disorders involving impaired but treatable prefrontal function
- schizophrenia
- depression
- PTSD
- drug addiction
