Task 2 Flashcards
2.1: Which brain parts does the lPFC in humans consist of?
IFS (inferior frontal sulcus) & IFJ (inferior frontal junction)
2.1: IFJ - where it is located?
at junction between posterior IFS & precentral sulcus
2.1: What does area 46/the principal sulcus in macaque monkey correspond to in humans?
Area 46 in principal sulcus (PS) macaque –> IFS in human brain (–> area 46 in humans in middle frontal
gyrus!)
2.1: Which areas does the lPFC correspond to in monkeys + humans?
posterior PS in macaque monkeys & posterior IFS + IFJ in humans
2.4: What is PFC generally involved in?
- representing acquired relationships between various pieces of information (necessary for intelligent behaviour)
- important for temporal integration
- learning is important in the formation of PFC representations & organization
- extracts information about the regularities across experiences (impart rules to guide thought and action)
- Rule-dependent activity
2.4: Miller’s model –> Representation of task elements
- there are several cues & possible actions interconnected
- Units in the PFC are internal / hidden units (intervening stages of processes)
2.4: Miller’s model –> Which areas are the dorsal + posterior lateral PFC regions interconnected with?
cortical areas that process visuospatial & motor information
2.4: Miller’s model –> Which areas are the ventral + anterior lateral PFC regions interconnected with?
cortical areas that emphasize information about visual form and stimulus identity
2.4: Miller’s model –> Which areas is the ventral (orbitofrontal) PFC interconnected with?
associated with subcortical structures that process ‘internal’ information
- 4: PFC –> SUSTAINED ACTIVITY WITH DISTRACTORS
- What does it mean?
- How is it mediated?
- How does it relate to WM tasks?
-PFC maintains goal-relevant information without distraction via a gating signal –> mediated by dopamine influx
-Holds temporary information on-line (to form association)
==> Sustained activity in PFC extends beyond WM tasks
- 4: PFC –> TOP-DOWN CONTROL & BIAS
- How does PFC biases processing?
- Which kind of influence?
-PFC activity provides an excitatory signal that biases processing in other brain systems towards task-relevant information 🡪 top-down influence
2.4: PFC –> What can PFC do through bias?
PFC can select the neural pathways needed to perform the task (flexibly guides flow of activity)
- 4: PFC –> RULE-SWITCHING
- What is PFC needed for?
PFC is needed for implementing task information (esp. when familiar behaviours need to be flexibly combined into a coherent sequence)
2.4: Wisconsin Card Sorting Test –> How do pp with lPFC damage do on the task?
can learn the first rule but then they are unable to escape it: they make many errors because they lapse back to the earlier rule
–> cannot flexibly switch between rules/tasks
2.4: Evidence of PFC biasing perception (Xu paper)
- IFJ (=inferior frontal junction) was synchronized with FFA when faces were attended & with PPA when houses were attended
- IFJ was leading FFA/PPA with a constant time-lag of about 20 ms –> IFJ thus appeared to be the driver of the synchrony
2.4: Through which mechanisms does IFJ (PFC) bias perception?
through neural synchrony with posterior regions where the actual sensory signals are contained
2.5: Evidence that actvivity in PFC does not represent WM demands- Passingham
- different areas involved in maintenance of spatial location during delay period
- Posterior PFC
- middle PFC/DLPFC
2.5: Evidence that actvivity in PFC does not represent WM demands- Miller
- Learning associations (lPFC) can become automatic
- Less dependent on PFC for rules & tasks
2.5: Evidence that actvivity in PFC does not represent WM demands- Xu
IFJ –> involved in neural synchrony with other brain areas (interconnectivity of PFC)
2.5: Evidence that actvivity in PFC does not represent WM demands- Bunge
- LPFC not involved in maintaining rule representation in WM during delay period
- -> Activity during delay does not reflect WM alone
- -> WM much more complex
- -> LPFC not key component of WM
- ->More areas than lPFC involved in WM
2.5: Passingham –> what could sustained actvity reflect?
- Maintenance of sensory info
- response preparation
- transformation
- task rules
- goals/rewards
2.5: Passingham –> what’s special about sustained activity in PFC?
- prospective use of that information
- PFC lies at top of the sensory & motor hierarchy
- -> receives information from all sensory modalities & sends outputs to the motor system
2.5: Inactivation of which area interferes with WM tasks?
Inactivation of PFC but not parietal cortex interferes with delayed response performance
2.6: Animal studies- WM- methods
- Monkeys see stimulus
- Delay
- Another Stimulus
→ have to decide whether stimuli match
or not (match rule vs. nonmatch rule)
2.6: Animal studies- WM- results
-neurons fired around area that translates to IFS in
humans
- neurons for match rule: fire more during delay period → correlated to keeping ‘online’ of which rule is being followed
2.6: Human studies- Spatial Delayed Response Task- Methods
- Fixation cross → you fixate it with your eyes
- A stimulus appears but you do not look at it
- Stimulus disappears
- You need to remember where it was
- Delay period (during this period PFC is monitored)
- Fixation cross disappears → Response: you make an eye movement to
where the stimulus was
2.6: Human studies- Anti-Saccade Task
only difference: when fixation cross disappears → you make an eye movement to the opposite direction of where the stimulus was
2.6: Which info about neurons can you get when you combine the Spatial Delayed Response Task & Anti Saccade Task?
→ with both tasks combined: you can dissociate the neurons that code for the stimulus & the ones that code for the response itself
2.6: What are the findings of the Spatial Delayed Response Task & Anti Saccade Task?
- neurons in lateral PFC maintain the location of the stimulus for later use
- groups of neurons code for different things, e.g ., some code for saccade, some for rules…
2.6: Is lPFC as locus of working memory? Why (not)?
NO,
- neurons also active during non-working memory tasks
- delay activity also seen in dorsal parietal cortex
2.6: What is special about the PFC delay activity? (3 things)
- only inactivation of lPFC interferes with delayed response
- more delay activity when a response can be prepared during the delay
- only lPFC activity predicts recall after distraction
2.6: SO what does lPFC actually do/is important for?
- responsible for stimulus response mapping & control of task execution
- representation of abstract rules
2.2: What does the central position of the lPFC suggest for its role in cognition?
- positioned between the (dorsal) attention systems & the medial action selection structures
- transfers visual cues into motor goals (FEF)
- uses info from attention system to make a motor goal
- 3: Why can the lPFC be seen as the integrator of cognitive episodes?
- -> temporal representations of all relevant task elements (Passingham paper –> 5 kinds of info activity of lPFC cells reflect)
- Maintenance of sensory info
- Response preparation
- Transformation
- Task rules
- Goals/rewards
2.3: Why can the lPFC be seen as the integrator of cognitive episodes? –> Place holders/tags?
- representations are place holders/tags for real representation in remote regions (sensory areas, language or motor areas)
- -> lPFC: involved in task acquisition , but not in long-term storage (more posterior cortex)
- -> lPFC: biases selection of certain pathways
2.3: Why can the lPFC be seen as the integrator of cognitive episodes? –> feedback modulation
-via feedback modulation lPFC optimizes/keeps active these remote representations & prioritizes processing of task-relevant elements
