Cognitive, Executive Function and Decision Making Flashcards
Executive functions
- Identifying goals
* Assigning value to different choices: evaluate what is more important. We associate value to objects that do not have any intrinsic biological value. How do we assign value to things, compare value and make decisions based on value? –> importance of executive system.
* Keeping a main goal in mind while working toward sub-goals. Understanding context; the rules necessary to achieve goals. Sub-goals are steps to reach the goal. Humans are good at keeping the goal in mind and figuring out what subgoals are necessary to reach the goal.
* Planning for the future; imagining future scenarios. We can think and imagine the future. We also have a narritive of the past and we can use it to create possible scenarios of the future and guide our future behaviours. - Inhibiting inappropriate behaviors (especially if not appropriate in specific context).
- Changing strategies. Trying something new when something is not working. If somone has frontal lobe damage, they have trouble chaning strategies.
- Assigning value to different choices
- Working memory (ability to hold something in your mind). Allows you to act on abstract things.
What region of the brain is central to executive function
Prefrontal cortex is central to executive function.
* The prefrontal cortex is an area that got big in humans compared to animals. It shows our ability to do more complex executive functioning. It reflects the complex ways that we can control behavior, the complex forms of executive control that we have over our behaviour compared to other animals.
What is the frontal lobe involved in?
- The frontal lobe is involved in action.
- It is functionally organized along a rostral- caudal gradient.
- The abstract aspects of action (e.g., “I want to make a sandwich, but first I need to buy bread.”) are rostral, whereas the specific action required to achieve the abstract goal (e.g., the movements involved in slicing bread) are caudal.
- The areas that are most caudal are most directly involved in movement. The areas that are sort of intermediate are involved in higher order aspects of movement control.
- The farther forward we get in the prefrontal cortex, the more that is an area that is involved in the most abstract aspects of planning.
The two important regions of the prefrontal cortex
- Dorsal-lateral regions of prefrontal cortex are interconnected with premotor and sensory association cortex. (Prefrontal cortex does not connect directly to primary motor or sensory areas.)
- Ventral-medial regions are interconnected with temporal lobe and subcortical limbic structures (amygdala, hypothalamus). Involved in emotional states and connections between emotional states and physiological changes in your body. What allows you to modulate your emotional responses appropriately in social context and control your behavior. Patients that have damage to these regions suffer from a certain set of executive control deficits that are related to social cognition and related to the ability to control impulses.
- Dorsal-lateral regions are more associated with “cold” executive functions (e.g., solving a multistep math problem), whereas ventral-medial regions are more involved in “hot” executive function (e.g., regulating social behavior).
Cognitive Control
- Cognitive control is a specific aspect of executive function.
- Humans can override stimulus-evoked, habitual and automated, responses in novel situations that require behavioral flexibility and innovation. Humans can override bottom-up stimulus responses if the context is inappropriate (for example, driving on the left side of the road instead of the right side when you are in the UK).
- We can engage in complex and extended behaviors and put off short term desires in pursuit of long-range goals. This is self-control and this ability is less developed in young children. They tend to be more impulsive and have trouble suppresing short term goal/reward in the pursuit of long-term goals.
- Cognitive control is associated with feelings of mental effort and conscious control of attention and will (will power). It is a “top-down” process. Feels like a lot of effort and often feel fatigued after. Part of the idea of cognitive control is that you can use effort or a sense of will to overcome sort of automated stimulus response relationships if the context is appropriate or in specific context.
- The Stroop test and go-no-go tests are among the tests used to assess cognitive control in the lab.
Stroop test
- Say the color of the font instead of the actual written color.
- Have to overide the written color and constantly remind yourself of this (so keep this in your mind). Follow the rules of test.
- More difficult the test = the more the frontal lobe is activated.
Miller and Cohen Model of Prefrontal Cortex and Cognitive Control.
In the absence of top-down control from prefrontal cortex, different output pathways compete for expression in response to the stimulus (GREEN). The mapping between the stimulus and saying “green” is strong, so that response is expressed and inhibits the alternative response (“red”).
Miller and Cohen Model of Prefrontal Cortex and Cognitive Control - when you are doing the stroop test.
Prefrontal cortex provides a bias signal that amplifies the selected response (“red”), and results in inhibition of the alternative response (“green”). In this model the prefrontal cortex uses its knowledge of the rules, goals, etc., to direct traffic in other brain regions.
* The Miller and Cohen model is proposing that the two pathways/connections are not in the frontal lobes. That is not what the frontal lobe is doing, the frontal lobes are looking back down on the other parts of the brain and applying this bias.
* The role of the executive function in the frontal lobe is not to actually implement the behavior. The role of the prefrontal cortex is to be a conductor: switch on a pathway and inhibit another pathway.
* The Miller and Cohen model proposes that the lateral prefrontal cortex is actually exerting the control and medial regions of the prefrontal cortex are involved in monitoring the errors.
* The key idea of this model is that the frontal lobes are exerting executive control (top-down control) over sensory motor connections.
The 4 networks involved in cognitive control.
Cognitive control involves interactions between brain networks that connect the prefrontal cortex and the parietal lobes, along with other cortical and subcortical structures.
* Cerebral cortex does not function as a set of discrete areas.
* The cerebral cortex is organized into distributed networks (different regions of the cortex that are sometimes quite far apart from each other but still interacting with each other to form these networks) that regulate cognitive control.
* Frontal lobes are involved in executive function but they arevinteracting with various parts of cerebral cortex in ways that form these dynamic netwroks.
* Connections between these regions are dynamic, they are changing all the time. How they change determines how the brain is interacting with the world.
* There are 4 distinct networks
Default mode network
The default mode network is active when your mind is turned inward. It is involved in your thoughts about yourself, episodic memory, social cognition and mind wandering, i.e., the ongoing internal narrative of your live. The default mode network decreases activity when you reorient attention to engage in the world around you.
* Study where subjects in scanner while doing a task: flash letters and flash words then subtract the difference between the two. This will give you an image of the regions in the brain that are active when reading words.
* It did not matter what the person was doing. Always regions that decreased activity when starting task (compared to person doing nothing) - this is called the default mode network. The colored regions decrease in activity when subjects go from waiting quietly in the scanner to engaging in a cognitively demanding task.
* This network is deactivated when you shift your attention from your inner thoughts to something in the exterior world.
Key cortical nodes of the default mode network
Key cortical nodes of the default mode network are the medial prefrontal cortex, medial parietal lobe (posterior cingulate cortex and precuneus) and the angular gyrus
Key cortical nodes of the default mode network
What happens when you shift your attention from internal thoughts to interacting with the world?
When you shift from your internal thoughts to engage with the world, activity in the default mode network decreases, whereas activity increases in networks (different network:control network) involved in attention and cognitive control.
Control network: top down control
Attention network: allocating attention/directing attention - involved in the top-down attentional control (control what you are attending to).
Bottom up attentional network and the salience network overlap a lot - they may be the same network.
Salience network
The salience network monitors internal and external sensory input and initiates the switch between the default mode and control/attention networks.
* Enables the switching between the attentional and default mode.
- deactivate default mode (stop daydreaming)
- and start directing attention and control.
Together the insula and cingulate cortex make the salience network, its role is to switch between default mode network and control network.
2 elements of Miller and Cohen networks
1) The Controller: exerting the control. Involves the dorsal and lateral regions of cortex.
2) The Error Detector: monitoring errors. Involves Cingulate Cortex.
- The exertion of control in the Miller and Cohen model involves control network.
- The error detector is involving the salience network.
The insula
- The insula (especially in the right hemisphere) integrates interoceptive information (i.e., relating to the physiological status of tissues in the body). It tells us how we “feel”.
- The insula is sometimes referred to as limbic sensory cortex, because of its association with pain, temperature and visceral perception.
- Activity in posterior regions corresponds to the actual intensity of stimuli (e.g., heat applied to the skin surface) whereas activity in anterior regions corresponds to subjective feelings (e.g., pleasant warmth).
- Insula is hidden behind the lateral sulcus
- Salience network is going to be monitoring what is going on and it is connected to the sensory system because this allows external stimuli to catch your attention and remind you to do something.
Activation in the insula (fMRI)
fMRI images showing activation of right insular cortex in response to
(a) recall- induced anger,
(b) cooling of the hand and
(c) pictures of human faces showing disgust
these 3 experiments (a,b,c) all have in common:
- elicit a certain feeling.
- certain changes in physiology that are associated with this emotion/feeling.
- insula is monitoring body state
- insula is activated indicating something is happening.
From this experiment, we conclude the insula is
- insula is a high order somatic sensory cortex (not a primary sensory area)
- lots of info coming in from your senses (external and internal)
- insula is in charge of the subjective evaluation of sensory stimulus. Ie, place your hand on something hot (the htter = more regions activated). The insula is evaluating the sensory input (mix of your perceived level of heatness and actual experience itself).
- the right insula is important for the subjective experience of your body (ie, pain).
- insula is activated in all of these cases. This is why it is part of the salience network, it is integrating information and sending an alert signal saying something has changed in the environment and that needs to be adressed.
Interoception
- You can think of the dorsal column medial leminiscal pathway and the anterior lateral pathway as two different systems (even though they make up the somatic sensory system).
- The dorsal column medial leminiscal system (fine touch system) is giving you info about the world.
- Anterolateral pathway is basically a system telling you how you feel. If you are in pain or cold, you are not feeling good. - Interoception = integrate the inputs that are coming in from inside your body. System telling you how you are doing, how you feel, whether your body is ok right now. This system involves delta and c fibers coming from the skin surface and also coming from inside.
- Interoceptive sensory neurons carry information about body homeostasis. They tell the brain how you “feel”. This system includes afferents from the spinal cord and from cranial nerves VII, IX and X.
- Afferents project to the nucleus of the solitary tract, the parabrachial nucleus and the periaquaductal gray. The main cortical destination for interoceptive sensory input is the insula.
The nucleus of the solitary tract:
- found in brainstem
- main input for sensations that are coming from inside your body and from your body’s surface
The parabrachial nucleus is integrating the inputs of these interceptive signals and also regulating outputs that are going out through the autonomic nervous system.
The periaquaductal gray is involved in threat response and plays a role in modulating pain stimulus. Stimulation to the periaqueductal gray or application of opiates diretly is a very powerful analgesic (animals will feel no pain).
Neurons in the lateral prefrontal cortex during the delay of the task
- Neurons in lateral prefrontal cortex continue to fire during the delay, suggesting they are involved in holding the visual image “in mind”.
- Fire at start, during and end of delay.
- The key point of this is that there are neurons in the lateral regions of pre frontal cortex that will continue to firing during that period when the animal or human is holding the image in mind. Suggests that these neurons are involved in working memory (keeping the memory activated).
Baddeley and Hitch model of working memory
- This model is a simple description of something complex to allow us to do experiments.
The visuospatial sketch pad:
- hold image in your mind (actively in working memory)
- Involves reactivation, finding stored memory and reactivating those brain regions that are involved.
The Phonological loop:
- comprises a phonological store that is dedicated to working memory and that serves to temporarily hold verbal information.
- ie: saying the phone number over and over again until you have to say it.
- Involves reactivation of an articulatory loop. Inner speech is used to reactivate, or “refresh,” the representations in the phonological store.
Central Executive:
- regulates what is getting loaded into the visual sketch pad and phonological loop based on context.
What systems does working memory involve?
- More recent models propose that working memory involves top-down attention, which activates sensory, motor or symbolic (e.g., a telephone number) representations in the brain.
- In this case, the attentional systems would correspond to the central executive. Meaning the central executive would involve the control and the dorsal attentional network.
- So control network and attentional network are going to be involved in activating the parts of brain that were involved in having the experience in the first place.
- These executive control networks are re-activating in some way the same circuit that were activated when you had that experience in the 1st place. This is eleciting the memory of the experience and putting it into working memory.
Phineas Gage
- Studies of patients with lesions in ventromedial prefrontal cortex suggest that this region connects visceral responses and emotions to decision-making.
- ie, Phineas gage - got a tamping iron in the front of his brain. Never loss consciousness. After he recovered, he lost one eye but acted quite normal. Intelligence was the same but personality completely changed.
- Had no impulse control, was very irresponsible, kept making terrible decisions.
- This accident caused a deficit in his ability to make good decisions.
Ventromedial prefrontal cortex
Ventromedial prefrontal cortex includes the orbitofrontal cortex (where your eyes are), anterior cingulate cortex and other medial prefrontal regions.
* Dorsal and lateral regions of PFC are involved in cold executive function.
* Ventral and medial regions are more important, have lots of connections with subcortical structures that are involved in feelings and emotions - important for hot executive function –> social cognition and knowing the appropriate behaviour
* Patients with damage to the ventromedial prefrontal cortex have behavioral deficits in terms of their ability to behave socially (similar to Phineas Gage). They also have clear deficits in decision making and this makes it difficult for them to live normal and effective lives.
The gambling test experiment
- Do this test with controls and patients with damage to VMPFC.
- They have 4 decks: A,B,C,D
- They are given money and the object is to get as much money as you can
- each turn flip over one card.
- Initially, you will win more money with decks A and B (bigger payoffs) but there are also bigger loses. So once you realize this, you start to catch on and chose decks C and D (low win, low risk) as there will be a bigger payoff in the end.
- Control subjects initially select from all four decks but over time they select more and more deck C and D.
- While they do this test, you also measure galvanic skin response (measure of arousal). When subjects are playing this game and are losing money, there is an arousal response - increase in galvanic skin response.
- This increase in arousal actually happens before the participant starts to switch to the right decks.
- When they reach for decks A and B there is an increase in arousal which precedes them changing their behavior.
- It is almost as if the persons physiological response (body) is sending a signal to the persons brain telling them that those are the bad decks.
- This makes sense as decisions seem to be intuitive and rapid, they are based on a feeling that you get.
- Patients with damaged VMPFC continue to chose decks A and B despite the high loses. These patients also do not exhibit a change in galvanic skin conductance (no arousal response). This intuitive “bad” feeling is not happening for them, so they do not change their mind.
- Rational thinking is intamitely connected to these other processes that are involved in the physiological changes in your body and the relationship between those physiological changes and how you feel.
What is the connectivity between these ventral and medial regions of the prefrontal cortex and these feelings and emotions?
The ventromedial prefrontal cortex and insula are interconnected with the amygdala and the hypothalamus, subcortical structures involved in emotions, feelings, motivation and associated physiological states.
* VMPFC is connected to a variety of subcortical structures that are involved in our physiological responses to emotions and the way that feelings/emotions influence learning.
Hypothalamus and interoceptive system
- Hypothalamys is connected up to the intercopetive system.
- The hypothalamus projects to autonomic neurons and central pattern generators in the brainstem and spinal cord to coordinate autonomic reflexes and stereotyped behaviors involved in drive-related responses and homeostatic control. These brainstem structures include the nucleus of the solitary tract, the parabrachial nucleus, and the periaqueductal gray.
Hypothalamus and periaqueductal gray
The hypothalamus coordinates which responses are expressed, but the responses themselves are organized in the brainstem structures. For example, in a frightened cat, the periaqueductal gray coordinates piloerection, hissing, and arching of the back.
Amygdala (part of subcortical region)
The amygdala (nucleus-cluster of neuurons,dendrites and synapses) is a key interface between autonomic response, emotions, and conscious feelings.
* Amygdala is very much connected to the relationship between these physiological changes and feeling states and how this is related to behavior and cognition.
* You can see in image that the amygdala is relateed to the hippocampus.
* at the very anterior end of the hippocampus, that is where the amygdala is.
Location of amygdala
- The amygdala lives in the temporal lobe, inside the uncus
Brain activation and the trolley problem
The Trolley Problem activates lateral prefrontal cortex, whereas the Footbridge Problem activates ventromedial prefrontal cortex.
* Trolley problem: dosal lateral PFC is activated during this problem. Cold logical executive function.
* Footbridge problem: elicits a stronger emotional response. Area of activation = ventral medial PFC. Links thinking and decision making to visceral emotions.
