Term
| What is Executive Function? |
|
Definition
| Orchestration of a number of cognitive functions integrating internal and external sensory information to modulate behavior in order to carry out effective goal directed actions |
|
|
Term
| What are the functional divisions of the PFC? |
|
Definition
Composed of heteromodal and limbic cortex
1) Lateral PFC
2) Orbitofrontal
3) Medial (anterior cingulate) PFC |
|
|
Term
| What is the structure of a basic PFC-subcortical processing loop? |
|
Definition
| PFC.....Caudate....SN/Gp....Thalamus (medial dorsal).....PFC |
|
|
Term
A patient is having difficulty planning, maintaing attention and following multi-step commands (recipes).
She feels like she is always "losing her train of thought."
Where might this patient have a lesion and how might it produce these symptoms? |
|
Definition
Lateral PFC
- Critical for Working Memory (especially reacting to environmental stimuli) and Goal-directed behaviors
- Attentional deficits arise because Top-Down processing of LPFC to brainstem and basal forebrain cholinergic and monoaminergic centers is disrupted
- Planning and goal-directed behavior deficits are because of extensive connections of LPFC to parietal and temporal lobes, which get "where" and "what" information |
|
|
Term
A patient arrives in your office complaining of motor, arousal and emotional regulation difficulties.
She can follow your fingers in an oculomotor task, but has no response to a noxious stimulus.
Where might she have a lesion and why are these deficits seen? |
|
Definition
Damage to Medial PFC (Anterior cingulate cortex) arising from ACA stroke, tumors, or degeneration (frontotemporal dementia)
- Cortical area with highest density of DA receptors (role in executive function), with dense connections with motor, reward and cognitive control centers
- The lack of responsiveness to noxious stimuli is akinetic-mutism. |
|
|
Term
| What evidence supports of role for DA signaling in executive function? |
|
Definition
1) PFC receives highest concentration of mid-brain DA output
2) PD subjects demonstrate disorders related to executive function
3) Monkey and Human research where disorders of working memory are linked to DA signaling. |
|
|
Term
A patient is impulsive, careless and exhibits explosive behaviors with OCD tendencies.
He was previously diagnosed with a herpes infection.
What could be going on and why are you seeing these symptoms? |
|
Definition
Herpes encephalitis leading to damage to the Orbitofrontal Cortex (integrating emotional and memory responses, the internal, to environmental stimuli)
OBPFC had medial and lateral circuits with strong connections to ventral anterior and medial dorsal thalamic nuclei as well as limbic structures |
|
|
Term
| What types of events lead to affective and social disorders because of frontal lobe damage? |
|
Definition
| Damage to the OBPFC occurs with TBI (located on floor of anterior cranial fossa), Frontotemporal dementia and herpes encephalitis. |
|
|
Term
| What neural substrates modulate "top-down" and "bottom-up" processing during social cognition? |
|
Definition
1) Dorsal (bilateral) attentional system for "Top-Down"
- frontal-parietal system suppresses distractions ("where pathway")
2) Ventral (right hemisphere) attentional system for "Bottom-up"
- Ventral-lateral PFC "reorienting system" gives attention to salient, novel stimuli |
|
|
Term
Which neural substrates form the basis for Theory of Mind?
What clinical scenarios involve disruption of these pathways? |
|
Definition
1) Ventro-medial and orbito-frontal cortices through connections to amygdala, insula and sub-cortical structures
2) Autism, Schizophrenia, Frontotemporal dementia, TBI |
|
|
Term
| What are some useful strategies for investigating frontal lobe and executive symptoms at the bedside? |
|
Definition
1) Letter and category fluency (generate words in a category)
2) Alternating verbal sequences (1a-2b-3c)
3) Spelling things backwards, serial subtraction
4) Sequenced hand movements (first-palm-side)
5) Copying repeated sequences |
|
|
Term
| Explain the functional/anatomical organization of the PFC |
|
Definition
Comprised of heteromodal and limbic cortices and acts as neural "buffer between stimulus and response."
1) LPFC- attention, focus and working memory (goal-directed behavior in response to environmental stimuli)
2) MPFC (anterior cingulate)- intentions to actions, reward and error monitoring (highest density of DA-R)
3) OFC- emotional and memory responses to internal/external stimuli (social decorum and inhibition) |
|
|
