Conscious Control Part 1

Question 1

What guise of consciousness does the topic of conscious control fall under?

Answer 1

Device- ‘Who’ is in control of our behaviour

Question 2

What part of the brain is deactivated during sleepwalking?

Answer 2

Frontal cortex

Question 3

What behaviour change was noted in Phineas Gage after his frontal brain impaled?

Answer 3

”He is fitful, irreverent, indulging at times in the grossest profanity, impatient of restraint or advice when it conflicts with his desires; at times pertinaciuouslyobstinate yet capricious and vascillating. His friends and acquaintances said he was no longer Gage”

Question 4

In a similar case what was observed in patient EVR and what damage did he suffer?

Answer 4

He was an accountant aged 40 and had a large orbitofrontal meningioma removed. After the operation he still had a remarkable IQ of over 130 and performed well on all tests however; He quit his job, had ill judged partnerships, went bankrupt. Disorganised, unpunctual, unable to hold down job. Divorced, unwise marriage, divorced again two years later. Unable to complete simple plans e.g going out for dinner.

Question 5

What seemed to be observed in both of these cases (EVR, Phineas Gage)

Answer 5

An inability to control lower level impulses

Question 6

What specific type of behaviour was noted in studies with these type of patients (2)

Answer 6

Utilisation behaviour; The tendency to grasp common objects when presented, and perform the function commonly associated with the object. e.g putting on two pairs of glasses when handed them, pissing in bottle without considering environment.

Imitation behaviour; the tendency to imitate the gestures, actions and sentences of the person in front of you.

Question 7

What collective name did the researcher give to utilisation and imitation behaviour? What causes this behaviour?

Answer 7

Prefrontal lesions/ shutdown create ‘environmental dependency’, more direct following of impulses, no long term goals, less inhibition, less social norms, etc

Question 8

How would this environmental dependency behaviour differ from person to person with the same stimulus

Answer 8

The responsive behaviour they had was in concordance with their pre damage habits (e.g making bed, smoker, non smoker etc.)

Question 9

What functions therefore appear to correlate to which stages of the sensory-motor hierarchy?

Answer 9

Polymodal association cortex (sensory)- prefrontal cortex (motor) involved in new and new and flexible stimulus-response associations: flexibility

Unimodal association cortex- Premotor cortex (lower) more involved in established, well-learned stimulus response associations: routine (e.g sleepwalking)

See doc for diagram

Question 10

What is counted as the frontal cortex?

Answer 10

Anything in front of the central sulcas (includes motor cortex)

Question 11

What is included in the prefrontal cortex looking from outside the brain?

Answer 11

Anything frontal to motor, sometimes frontal to PMC/ SMA

Question 12

How does the size of the prefrontal cortex in humans compared to other animals?

Answer 12

Much smaller ratio of PFC vs rest of brain for subhuman species
•increases from squirrel, to cat, to rhesus monkey, to dog, to chimpanzee, to human

Question 13

How is the PFC neurologically defined?

Answer 13

Cortex connected with Dorsomedial Nucleus of the Thalamus

Question 14

In what other way is the PFC relatively unique in terms of its connections?

Answer 14

It has bi-directional connections with almost all parts of the brain

Question 15

Name the cortical areas of the brain in which the PFC has bi-directional connections to (3)

Answer 15

Parietal, temporal, occipital lobe

Question 16

Name the sub-cortical structures in which the PFC has bidirectional connections to (6)

Answer 16

thalamus, basal ganglia, cerebellum, amygdala, hippocampus, brainstem nuclei

Question 17

Name the areas in the frontal lobe which it has bidirectional connections to (2)

Answer 17

pre-motor, motor cortex

Question 18

Name the areas in the contra-lateral frontal lobe in which the PFC has bidirectional connections to

Answer 18

pre-frontal, pre-motor, motor cortex

Question 19

What does this ride range of connections allow the PFC?

Answer 19

Therefore, pre-frontal cortex can coordinate processing across wide regions of the CNS

Question 20

Name three ways in which the PFC can enable flexibility of responses

Answer 20

1. Working memory, so that longer stimulus-response contingencies are possible, delayed responses
2. inhibiting direct response
3. adding ‘value’ to choice options, and updating these values on the basis of experience

Question 21

How is this working memory function assessed in monkeys?

Answer 21

WM delayed-response task:
Monkey sees one of two wells baited with food. After delay period, animal retrieves the food. Location of food is randomly determined. This requires WM as at the time of response there are no external cues indication of the location of the food.

Question 22

How can the long term memory of monkeys be assessed?

Answer 22

Associative memory task;
Food reward is always associated with one of two visual cues. Location of food and cues randomly determined. This requires long term memory because the animal must remember which visual cue is associated with the reward.

Question 23

How is the role of the PFC assessed in these tasks and what are the results?

Answer 23

By making lesions of the lateral prefrontal cortex. This impairs performance on the WM task but not on associative memory task. (this is also observed in pre-frontal patients, but only with delayed alternation tasks.

Question 24

What is the ‘bottom line’ of what frontal animals can and cannot do regarding these types of tasks? (4; 1,3)

Answer 24

Bottom line: they can learn stimulus-food associations, they cannot do reversal of learned associations, things that involve a delay, or a combination of reversal and delay

Question 25

What tasks measuring similar functions is often given to human patients suffering from frontal regions? (2)

Answer 25

Wisconsin sorting task

N-Back task

Question 26

Describe what is involved in the Wisconsin sorting task

Answer 26

=>Deck of cards containing objects varying along three dimensions; shape, colour and numerosity.
=>Four target cards are placed down and top card of the deck is placed under one of four target cards.
=>The participant then has to sort cards according to one experimenter defined sorting rule.
=> 2 catches
+ subject is not informed of the sorting rule, they must discover it through trial and error (experiment gives correct/ incorrect feedback)
+ Once subject has learned to sort by one dimension, the experimenter changes the rule without informing the subject.)

Question 27

What two aforementioned cognitive abilities does this task require?

Answer 27

Flexibility to discard a previously reinforced hypothesis ,

Requires WM to retain knowledge about relevance of certain dimensions on previous responses

Question 28

What is involved in pre-frontal patients who carry out this task?

Answer 28

They perseverate; keep applying initial rule after the switch, despite experimenter’s negative feedback (also they are slower in the initial task)

Question 29

What is involved in the N-back memory task?

Answer 29

All N-back tasks require that subjects
-attend to and encode each letter
-evaluate its identity
-respond to letters by pressing a button
Memory task (N>1) also requires that subjects:
-keep in mind the identity and order of the previous letters
-continuously update this mental record as sequence progresses
-these operations are central to the concept of the working memory

Question 30

What did pet scans reveal when recording during N-back tasks?

Answer 30

Parametric manipulation of load (2 back, 3 back) leads to increased involvement of dorsolateral PFC

Question 31

Describe the earliest findings regarding the neural mechanisms behind these working memory functions in the PFC

Answer 31

Delay activity: PFC neurons maintain firing after removal of behaviourally relevant stimulus until response

Similar to Posner cueing task, a fixation target was given, a cue was briefly shown, then a delay before a memory guided saccade. The monkey was trained to withhold the response until a ‘go’ signal (arrows) appeared. Prefrontal neurones can show sustained activity during these delayed response tasks. These cells did not respond during the cue interval . Rather its activity increased when the cue was turned off , and persisted until the response.

Question 32

Name theories attempting to answer what is ‘stored’ in these neurons

Answer 32

Location specific delay: cell is only active when cue is in movement field.

Different PFC neurons may encode object identity or location

Question 33

Is a location specific delay found in studies?

Answer 33

It is invariably found that they are location specific in studies, especially in frontal eye fields (in PFC) and dorsolateral PFC.

Question 34

Is there any evidence that different PFC neurons may encode object identity or location? Describe the study and findings

Answer 34

A monkey fixates of a point and is shown one of two objects (eg bell or box) to remember. There is then a “what” delay and both objects are shown in two places relevant to the fixation spot (e.g up and left). There is then a “where” delay and they are shown a choice of where the correct object was to which they have to make a choice.

In some neurons a different strength of delay activity depending on identity (‘what’) of object

In other neurons different strength of delay activity depending on location (‘where’) of object

Question 35

It would be a bit unrealistic to assume that all the visual information in the visual field and cortex is also replicated and stored in the PFC. What is an alternate explanation for these findings?

Answer 35

the idea is that PFC maintains precise stimulus properties via maintained activation of sets of neurons encoding the details. This is done via reciprocal (feedback) connections with temporal, parietal, and occipital cortex (see docs for diagram)

Question 36

What evidence has been found for (2) and against (1) the idea of maintained activation of sets of neurons encoding the details via feedback connections for memory?

Answer 36

Pro-
=> Maintained feedback activity in primary visual cortex of the monkey during working memory delay
=> Size of primary visual cortex determines capacity of working memory

Contra-
=> No maintained activity in fMRI signals signals of human subjects during working memory delay (only effect of attention)

Question 37

What complication is there to this apparently contradictory fMRI finding concerning the role of the visual cortex and PFC in WM?

Answer 37

The working memory is not represented in maintained activity, but content can be decoded from pattern of activity in V1 despite the activity not being higher. Eg when remembering a bell instead of a box

Question 38

Give another name for the concept of inhibiting direct response and describe two tasks which measures it

Answer 38

Typical task to measure inhibitory control: Go No-Go task: respond as fast as possible to stimuli unless there is a no-go cue (e.g a cross in the shape). A no go should be much rarer than a go stimulus.

Another way: Stop signal reaction task. Go responses (encourage to be as fast as possible) to two alternative stimuli. Occasionally the Go stimulus is followed after a delay (the SSD) by a stop sign. Then people should not respond.

Question 39

What activity is observed in the brain during these tasks?

Answer 39

The ability to rapidly abort planned or already ongoing actions is associated with a widespread right-lateralised frontoparietal “inhibition network”, most prominently the right inferior frontal cortex. (IFG)

Question 40

How is the stop signal reaction time (SSRT) estimated in the stop signal reaction task? What is this supposed to measure?

Answer 40

Go reaction time (GoRT) - stop signal delay (SSD, interval between task stimulus and stop signal). the SSRT can then be estimated by changed the SSD so that there are 50% successful responses and 50% inhibited responses (median). That is a good estimate for the time it takes to process the stop signal. It is therefore a measure of speed and strength of inhibitory control

Question 41

What brain lesion patients are impeded in this task? (2)

Answer 41

Damage to the right IFG was significantly correlated with SSRT, as was damage to the pars triangularis subregion of the IFG.

Question 42

What is meant by Non-utilitarian choices

Answer 42

Choices in which emotions interfere with logic (ie train dilemma, abandoning one guy to save a squad etc)

Question 43

Name a subset of people who appear to make way more utilitarian decisions than others

Answer 43

Patients with lesions to the (ventro) medial prefrontal cortex.

Question 44

What role does this demonstrate of the mPFC?

Answer 44

That it signals/ contributes ‘moral value’ to decisions

Question 45

What practical implication do these mPFC lesions have for patients in everyday life?

Answer 45

They have great difficulty in ordinary choices (where to go, what to eat etc)

Question 46

Describe a study which attempted to study the role of these brain areas in these valued decisions

Answer 46

Participants were divided into three conditions in which they were shown the same stimuli. In the first condition they were shown images and asked preference irrelevant age judgement (person age, age of building, painting). In the second condition participants were asked to gage the extent to which they liked or disliked an image. In the third condition they were two images and asked make a choice on what image they preferred (between two faces, two houses or two paintings.) Brain activity was measured

Question 47

What were the results of this preference relevant binary choice study?

Answer 47

the PCC (posterior cingulate cortex), Hippocampus, VS (ventral striatum/ nucleus Accumbens), ventromedial PFC together constitute a valuation system which dictates our choices.

This valuation system signals both individual and group value, generalises value over stimulus class, and works regardless of task demands. (in each condition and for each type of item. Also the same for personal and shared preferences)

Question 48

What is our internal value signalled by then?

Answer 48

Our internal value is signalled by a generalised and automatic VALUE system It assigns value to items we are confronted with, dictates our choices.

Question 49

A similar study was later carried out concerning car preferences, describe this study and the results.

Answer 49

Two conditions, shown the same cars. One condition had to evaluate the extent to which they liked the car, the other was passive exposure to the cars (Perform the fixation task.) In both conditions (high and low attention) neural responses predicted their preferences at about 75% success rate.

Question 50

What brain areas were involved in the high and low attention preference study? (2)

Answer 50

mPFC and insula

Question 51

A study was then carried out which measured emotional preference and behavioural change, describe this study.

Answer 51

Students were shown food and sexual images, brain responses were recorded, their BMI was measured and sexual behaviour was measured. One year later the same measurements were taken and it was found that the responses of the nucleus Accumbens (ventral striatum) to these images predicted weight gain and sexual behaviour increase in that year. This indicates that these value systems have an impact on the behaviour that we engage in, in real life.

Question 52

Where do valuation systems get these values from

Answer 52

To a large extent associative learning through the dopamine reward pathway in the brain.

Question 53

Describe what dopamine is and how it could contribute to these value systems

Answer 53

Dopamine is a signalling agent in the brain that’s crucial to memory formation, helps animals remember experiences, both positive and negative. This stamped-in memory gives animals the motivation to repeat pleasurable experiences.

Question 54

Describe this dopamine pathway in the rat brain

Answer 54

Produced in VTA and SN

From VTA goes rostral along Mesolimbic pathway and a more ventral and rostral mesocortiyal pathway.

From SN goes rostral in a more superior Nigrostriatal pathway.

See docs for diagram

Question 55

Describe this dopamine pathway in the human brain and the different areas it goes through with their functions.

Answer 55

Ventral tegmental area (VTA) (dopamine production area, signals reward or reward prediction) >

Nucleus Accumbens (NAc)(Motivation and goal-directed behaviour) > Prefrontal cortex

See docs for diagram

Question 56

How has the behavioural role of dopamine been studied in rats?

Answer 56

Rat is in a box with a lever. This lever is attached to a stimulater from which another lead loops around over a suspended elastic band, back into the box and into an electrode in his brain which stimulates an area releasing dopamine. Soon the rat gets ‘addicted’ to pushing this lever.

Question 57

How can dopamine therefore influence future behaviour?

Answer 57

Dopamine signals ‘reward’> pleasant feeling> reinforcement of behaviour that led to reward.

Question 58

Aside from these direct rewards how else can this reinforcement of behaviour take place?

Answer 58

From primary to secondary rewards: Pavlovian conditioning (positive) and associative learning and fear conditioning. (negative)

Question 59

What change is seen in terms of dopamine with associative learning?

Answer 59

Via associative learning the reward / dopamine signal can shift from the reward itself to the associated stimulus.

The dopamine signal is not about the reward itself, but about the difference between the expected reward and the actual reward.

Reward prediction error hypothesis

Question 60

Describe how further evidence was provided for reward prediction error hypothesis

Answer 60

Stimuli (CS) were associated with rewards with varying probability So when the predictive value of a CS is low, the dopamine neurons mainly fire on the reward. When the predictive value is high, they fire on the CS (stimulus on). When there is a long delay between CS and reward, dopamine neurons respond to the reward and no longer the CS (stimulus).(see docs for graphs)

Question 61

What alternate explanation could there be for this change in dopamine in reward prediction?

Answer 61

Statistical learning

Question 62

Describe an experiment which involved monkeys and this associative learning

Answer 62

Monkeys underwent an advertisement trial in which they were shown a logo along with an image of a dominant monkey in their group or a logo with a subordinate monkey. They were also shown logos next to a monkey perinea (basically monkey ready for doggy) or logos next to just monkey fur. Each stimulus lasted 3 seconds. In the decision trial, monkeys were shown two logos and could indicate a preference with no time limit.

Question 63

Describe the results of this experiments with ads and monkeys and what conclusions could be drawn

Answer 63

After exposure to advertisement trials, monkeys preferred to obtain food from logos previously associated with status (dominant) or sex (perinea)

Monkeys learn to associate brand logos with primary values (status and sex)

Question 64

How is this used in marketing and what brain regions is it involved with?

Answer 64

The Value (sex, charm, intelligence) transfers from US to CS. When showing these brands there will be a higher activation in the prefrontal cortex.

Question 65

How did Miller propose that the Prefrontal cortex mediates flexible control?

Answer 65

E.g when a phone rings

Phone rings + at home = dopamine reward signals = answer

Phone rings + guest = inhibition = don’t answer

Question 66

What would be required for Millners model to work? (6)

Answer 66

Reciprocal connections with sensory and motor cortex (yuh)

Inputs from reward systems (dopamine) (yuh)

Keeping information ‘on line’ (WM) because stimulus-response contingencies may span time (yuh)

Neurons encoding rules between input and output (if A&B > X) (?)

Rapid learning of such rules (?)

Neurons encoding abstract concepts like ‘being at home’ (?)

Question 67

Millner then went on a mission to discern how abstract this coding could get. Describe a study where he attempted this

Answer 67

he took dog and cat prototypes and porphed them so he had 60% dog/cats, 80% and the original 100% prototypes and drew a category boundary to see whether neurons reflect the dichotomous category or gradual transition to shape.

Post training them, he then had the monkeys complete a delayed match to category task in which monkeys saw two pictures, separated by a memory delay. If the pictures were from the same category, monkeys indicated yes by releasing a lever. If the pictures were from different categories, monkeys indicated “no” by continuing to hold the lever.

Question 68

What were the results of Millner’s dog and cat study?

Answer 68

the neuron’s response in the Prefrontal Cortex reflects the learned category rather than the gradual change in shape.

Question 69

Is this finding similar to the findings in the Inferior temporal cortex? Explain

Answer 69

Neurons in the Inferior Temporal Cortex (ITC) may also show category selectivity. Yet these neurons are overall much less ‘categorical’ than neurons in PFC. The ITC neurons often show different responses to various exemplars of the same category. (also much more visual)

Further research reveals that PFC neurons (unlike ITC) can quickly learn new perceptual categories of the same stimuli (e.g. long legged versus short legged animals).

Question 70

What contingency did he examine next?

Answer 70

Rule specific activity in PFC

Question 71

Describe the study in which Millner examined rule specific activity

Answer 71

Monkeys were trained to switch between two abstract rules: “match” and “non match”. A cue (reward/no reward or low/high tone) indicated what ‘rule of the day it was.’ If they had to match, they would have to release a lever at the same image as the cue, if it was a non match they would release the lever at the image that did not match the cue.

Question 72

What were the results of Millner’s study on rule specific cell activity?

Answer 72

He found that PFC cells have contingency rules (match vs non-match), irrespective of the response that is given (release or hold), the stimulus, or the cue that is used to indicate the rule (reward vs tone)

Question 73

What happens to these associations after a while according to the Millner model?

Answer 73

After a while, the learned associations will get ‘hardwired’ into lower levels (outside the prefrontal cortex) and becomes automatic behaviour. Prefrontal cortex is required to learning the acceptable behaviour in a new environment.