Lecture 30 Flashcards
Explain the anatomy and functions of the PFC
prefrontal cortex
- dorsolateral prefrontal cortex: planning and organizing of flexible behaviors (conflict-induced behavioural adjustment)
- orbitofrontal prefrontal cortex: receives sensory information and determines value after evaluation
- ventromedial prefrontal cortex: inhibition of unwanted actions
PFC involved in planning, judgement, insight, working
memory, cognitive control and behavioural inhibition
Feeling guilt/remorse, and interpreting reality depends on a well-functioning PFC
Give an example of how your dorsal lateral prefrontal cortex helps with decision making
conflict-induced behavioural adjustment
- naming the font colour of a word instead of the word (which are incongruent with one another)
- ex: stroop test
What is reduced volume of PFC and lack of interconnections with other brain regions linked to?
Reduced volume and interconnections with other brain regions linked to mental
disorders; also observed in those subjected to repeated stressors, those
incarcerated, sociopaths, and daily cannabis users.
Psychopaths showed reduced P3 amplitude for target stimuli, reflecting their reduced cognitive control and inhibition, increasing impulsivity and atypical prefrontal function
P3 amplitude is correlated with psychopathic traits even in a typical population
What diseases is prefrontal cortex dysfunction associated with?
Dysfunction correlated with schizophrenia, ADHD, and possibly depressive disorders, substance abuse
define: working memory
active and temporary representation of
information maintained for the short term to be used for goal directed behaviour
visuo-spatial and verbal phonological information is stored separately (visuo-spatial sketchpad vs phonological loop)
Discuss how PFC interacts with other cortical
regions to produce complex cognitive processes
and working memory
For example, when looking at an object and remembering what it is, the inferior temporal cortex is responsible for identifying the object (“what” pathway). This sensory information is then held in working memory through its interaction with the dorsomedial prefrontal cortex, which helps maintain the identity of the object over short periods.
In another example, when looking at an object and remembering its location, the parietal cortex processes spatial information (“where” pathway). This region works with the dorsolateral prefrontal cortex to retain spatial information in working memory, such as remembering where something is located in space.
What are transient memories ? Explain the two types and Which one prefrontal cortex is critical for.
Explain the brain regions that interact for each
- sensory: brief transient sensations of what you have just experienced (visual sensory memory)
- primary sensory areas, posterior parietal cortex - short term memory (holding onto phone number in ur head until you can put it in your phone) - rehearsal, encoding
- inferior temporal cortex and dorsolateral PFC
Explain what is meant by ‘hot’ and ‘cold’ executive
function
Cool executive function: is associated with relatively non-affective,
abstract situations; logic and critical analysis, inhibitory control [dorsal lateral PFC]
Hot executive function: is associated with affective, motivationally significant conditions; processes driven by emotion [orbitofrontal PFC and ventromedial PFC]
When confronted with a personally meaningful problem (e.g. reward
or punishment that needs to be solved, hot EF is most often involved)
Discuss the pathophysiology associated
Phineas Gage’s injury and recovery
Tamping rod drove thorough left prefrontal cortex resulting in left ventromedial dominant lesion
Prior, Gage was a hard-working, efficient railway foreman
Following injury he was frequently angry, obstinate, displayed impulsivity, lack of planning and socially-inappropriate behaviour
Next job: stagecoach driver - great story teller
Tonic clonic grand mal seizure many years after the accident
Discuss the sympatamology associated with dysexecutive syndrome
Disrupted ability to think and plan despite normal long-term memory
Ex: Chef lost ability to organize kitchen, leave things to burn, in denial about ability to cook
Patient K.F: failure to recall short sequences (short-term memory deficits)
- could not remember more than 2 numbers and inability to perform tower of hanoi
cool executive function affected - dorsolateral PFC lesion
Discuss the sympatamology associated with disinhibiiton syndrome
Damage to ventromedial prefrontal cortex or orbitofrontal cortex
As these areas are responsible for emotional control, personality, social and executive functions, these would all be affected
Lesions to dominant (often left side) produce negative effects (crying, yelling, acting out, inappropriate social interactions?), whereas lesions to nondominant side result in euphoria
Signs:
Excessive emotion, poor impulse control, poor social interactions
Inappropriate crying, anger, laughing, sexual behaviour
Disinhibition of normally repressed behaviours
Unaffected cognitive function and working memory
What would not be impaired with solely PFC lesion?
What would not be impaired: language, sensory perception, short and long term memory, motor control, general level of intelligence
Understand how experimental techniques can
be applied to study PFC function
Using EEG, measuring event related potentials, specifically P3 (third positive peak) which is thought to reflect cognitive control, attention, and response monitoring, all functions mediated by prefrontal cortex
In a visual oddball task, participants respond to a rare target in a stream of infrequent non-targets
The p3 wave becomes larger when a person sees the “odd-ball”
