psych 345 lecture 19 - The Frontal Lobes II

what do prefrontal connections do and what are the 2 kinds?

they are what empowers the frontal lobe, bringing information from all other parts of the brain to the frontal lobe/PFC

1. prefrontal afferents (inputs)

2. prefrontal efferents (outputs)

name the 3 major classes of prefrontal afferents

1. Sensory systems

2. hippocampus

3. other limbic structures

sensory systems receive…

processed info from all 5 sensory systems — getting more sophisticated, highly processed info — not directly from primary sensory regions

hippocampus and other limbic structures receive…

hippocampus — long term memory information

others - internal physiologic and motivational state information

name the 3 major classes of prefrontal efferents

1. sensory systems

2. motor structures

3. limbic system

sensory systems send…

connection back to all sensory systems from where it receives input (controlling where we attend and what we attend to)

motor structures

outputs that initiate, guide, and regulate motor behavior

which structures are motor structures receiving PFC output?

1. premotor cortex

2. basal ganglia

3. superior colliculus

limbic system function as a class of prefrontal efferents

the prefrontal cortex controls and regulates the limbic system

what does the PFC help regulate through limbic system outputs?

1. modulates memory

2. regulates emotional behavior

3. influences autonomic functions

4. influences endocrine function

5. feeling states (suppressing/delaying emotions)

what is the orbitofrontal and ventromedial cortex?

this cortex is involved in decision making, emotion, and social behaviors

what kinds of decisions are the orbitofrontal and ventromedial cortex involved in?

decisions based on

1. emotions

2. empathy

3. moral behavior

4. anticipations of rewards and punishments

the orbitofrontal and ventromedial cortex are highly connected with which of the following?

all of the above

where was phineas gage’s damage localized to and what was it the cause of?

phineas gage’s damage was localized to the OF/VM PFC and was seen to be the cause of his personality changes

somatic marker hypothesis

representations of feelings states that can be used to guide our choices — explaining how emotional responses can be used to guide decision makin

what is assumed of the somatic marker hypothesis?

that for each response option thought about, a somatic state (emotional response) is generated, occurring BEFORE a response is made

true or false: the iowa gambling task is poor evidence for the somatic marker hypothesis

false! this is a very useful task helping us study somatic markers

true or false: patients with OF/VM PFC lesions do NOT generate anticipatory GSR but DO experience negative emotion when pondering the association with risk

false! patients with OF/VM PFC lesions indeed do NOT sweat when thinking about the risky option and also do NOT experience negative emotion with risk and will continue to pick the risky option

how is phineas gage a good example of the effects of OF/VM PFC lesions

phineas gage’s lesion disrupted connections with his amygdala, hippocampus, and ACC — affecting his personality and loss of morals and empathy proving how the OF/VM PFC leads emotion-guided decision making, moral and social behavior, and integrates bodily somatic markers for choices

what is the lateral prefrontal cortex

the L PFC is in charge of executive control functions

what are executive functions?

the most flexible level of cortical function, helping establish plans and evaluate actions based on external and internal info

true or false: executive functions help suppress unwanted reflexive behavior

true!

name 7 examples of executive functions

1. inhibitory control/response inhibition

2. attentional control

3. set-shifting

4. planning and organization

5. working memory

6. problem solving

7. reasoning/decision making

what are the 2 most critical examples of executive function examples to understanding the role of the frontal lobe?

1. Inhibitory control/response inhibition

2. working memory

why is inhibitory control important and what brain region is critical for it?

it is the ability to suppress automatic stimulus bound behaviors and act only according to context and goals

• the PFC is critical for this function

what are the 2 things that happen when the PFC is damaged in terms of stimulus bound behavior

1. patients become reactive to external stimuli and are “stimulus bound”

2. primitive reflexes re-emerge because inhibition is lost due to circuitry damage

   1. sucking/rooting reflex

   2. grasp reflex

   3. babinski reflex

true or false: PFC damage leads to an inability to inhibit responses to external stimuli

true!

utilization behavior + example

compulsive interaction with objects in the environment without considering context

EX: touching, grabbing, using objects impulsively

how is visual grasp reflex related to utilization behavior?

the inability to maintain gaze on a goal because the eyes are drawn to the stimuli — this is like the visual version of utilization behavior

how does the PFC damage affect eye movements and why?

anti-saccade task: look away from an eccentric target

• patients with PFC damage are pro-saccade and cant override that reflexive response

• why?: because they lack goal representation; superior-colliculus-driven reflexes are disinhibited

why is working memory fundamental to inhibitory control?

working memory allows the PFC to maintain a goal or task rule and without it behavior is determined by whatever 

what is working memory?

the limited capacity cognitive system for holding, processing, and manipulating information

true or false: WM is not linked with attention

false! WM is closely linked with attention because what you focus on stays active in working memory and shifting attention shifts WM content

what are the two animal model tasks?

1. delayed response task

2. delayed saccade task

delayed response task in animals and lateral PFC lesion

the monkey has to remember the location of the baited food well without seeing it

• lesions of lateral PFC = task failure as the goal is forgotten the second its not visible

true or false: the delayed response task when done on infants showed failure as well

true! when a version of this task was done on infants under 12 months they also failed

delayed saccade task in animals (3 steps)

1. cue appears at 1/8 locations

2. delay (subject has to retain the location in memory when shown a blank screen)

3. “go”: generate eye movement → accuracy depends on PFC delay activity

in the delayed saccade task: if there is a focal lesion in BA 46, then…

it will impair performance for specific locations and their activity during the delay (memory scotoma)

what are the two human model tasks?

1. baddeley-hitch model

2. delayed response/verbal vs spatial WM

the 4 key components of the baddeley-hitch model

1. phonological loop

2. visuo-spatial sketch-pad

3. episodic buffer

4. central executive (controls everything.. how much attention to pay to everything)

what is the hypothesis of the baddeley-hitch model?

we can integrate the two information streams (verbal and visual/spatial) using the central executive and episodic buffer to solve problems moment to moment through our daily lives

verbal =

phonological loop in LEFT hemisphere

spatial =

visuo-spatial sketchpad in RIGHT hemisphere

delayed response/ verbal vs spatial WM task components

verbal WM: 4 captial letter —> delay —> lowercase probe —> match??

spatial WM: 3 locations —> delay —> location probe —> match??

what does the delayed response/verbal vs spatial WM task test?

this task tests maintenance and manipulation of info without external cues

explain the double dissociation of Lateral vs OF/VM PFC in terms of the iowa gambling and WM tasks

lateral PFC lesion = impaired WM task and relatively intact gambling task

OF/VM PFC lesion = intact WM task and impaired gambling task