Casey: Regions of the Brain (Biological) Flashcards
What theories was Casey’s study based on?
-The ability to resist temptation in favour of long term goals is an essential component of individual, societal, and economic success
-Alluring situations can diminish control
-Delay of gratification depends importantly on cognitive control.
-A study demonstrated the role the inferior frontal gyrus in our interpretations of facial expressions and a corresponding emotional response appropriate to the expression. A correlation has also been found between an avoidance of risky behaviour and greater excitation in the right inferior frontal gyrus
-It has been found that functionally, the ventral striatum facilitates and balances motivation with both higher level and lower level functions, such as inhibiting one’s behaviour in a complex social interaction. This region is most closely associated with reward
What previous research had been done for Casey’s study?
Previous research showed performance on a delay of gratification task in childhood predicted the efficiency with which the same individuals performed a cognitive control task (go/nogo task) as adolescents and young adults. Those who as preschoolers directed their attention toward rewarding aspects of the classic delay of gratification situation, such as focusing on cookies had more difficulty suppressing inappropriate actions than did their low temptation focus counterparts. The findings suggested the ability to delay gratification at a young age could predict one’s ability to control thoughts and actions when they were older.
What was the aim of Casey’s study?
To build on previous research and to determine whether delay of gratification in childhood can predict impulse control abilities and sensitivity to alluring or social cues when the participants were in their 40s.
What was the research method and design in Casey’s study?
A quasi experiment and a longitudinal study that used a repeated measures design.
What was the IV and the DV in Casey’s study?
The IV was whether the participant was a high delayer or a low delayer.
The DV was the performance on the impulse control task (in terms of reaction times and accuracy)
What was the sample of Casey’s study?
-562 four year old pupils from Stanford’s Bing Nursery school completed a delay of gratification task
-155 of these completed self control scales when in their 20s and then 135 of these when in their 30s
-117 of the 135 individuals who were above average or below average in their original delay of gratification performance as well as in the self report measures
-59 of the 117 agreed to participate in the longitudinal behavioural study
-27 of the 59 agreed to be part of a functional neuroimaging study (15 high delayers and 11 low delayers)
How were participants grouped in to high and low delayers in Casey’s study?
The preschoolers were each left in a room alone and left with a marshmallow. They were told that if they didn’t eat it, they would be given another one when the researcher returned. Those who ate the marshmallow were classified as a low delayer and those who didn’t were high delayers.
What was the procedure for experiment 1?
-Aim was to test impulse control
-59 participants, consented to take part in a behavioural version of a “hot” and “cool” impulse control task
-Completed 2 versions of the go/no-go task. The cool version of the task consisted of male and female stimuli which were presented, one sex as go (target) where the participant would have to press a button, and the other as no-go (nontarget) where the participant would withhold pressing the button
-Between each run, a screen appeared indicating which stimulus category was the target
-Participants were instructed to respond as quickly and accurately as possible
-Each face appeared for 500ms, followed by a 1 second inter stimulus interval
-A total of 160 trials were presented per run in a random order (120 go, 40 no go)
-The hot version of the go/no go task was identical but used happy and sad facial expression as a stimuli
-Tasks were presented using programmed laptops sent to participants’ homes.
What was the procedure for experiment 2 of Casey’s study?
-fMRI was used to examine neural correlates of delay of gratification. It was anticipated that low delayers would show diminished activity in the right prefrontal cortex and amplified activity in the ventral striatum in contrast to high delayers
-Participants completed a “hot” version of the go/no go task similar to experiment 1. Though there were differences in timing, number of trials, and apparatus
-Each face stimulus was present for 500ms with an interval ranging from 2 to 14.5 seconds
-Total of 48 trials per run in random order (35 go, 13 no go)
-Imaging data was acquired for 26 no go trials and 70 go trials for each expression
-The task was viewable by a rear projection screen and a Neuroscreen five button response pad recorded button responses and reaction times.
What was the key finding for experiment 1 with respect to reaction times in Casey’s study?
There were no effects of delay group on reaction time measures to correct go trials
What were the key findings for experiment 1 with respect to accuracy in Casey’s study?
-Participants performed with a high level of accuracy for correctly responding to go trials during both the cool and hot tasks
-Low and high delayers performed with similar accuracy on the go trials but low delayers made more false alarms in the no go tasks
-Low and high delayers performed similarly in the cool task but in the hot task, the low delayers performed much more poorly with a significant decrement in performance in the hot task compared to the cool one.
-Overall, the low delayers performed significantly less well in response to the emotional hot cues
What was the key finding in experiment 2 with respect to reaction times in Casey’s study?
The two delay groups did not differ significantly in reaction times in correct go trials
What were the key findings in experiment 2 with respect to accuracy in Casey’s study?
-Overall accuracy rates for the hot task were uniformly high for go trials with more variable performance to no go trials
-Low delayers committing more false alarms than high delayers in the no go trials
What were the key findings in experiment 2 with respect to imaging results in Casey’s study?
-The right inferior frontal gyrus was involved in accurately withholding a response
-Compared with high delayers, low delayers had diminished recruitment of the inferior frontal gyrus for correct no go relative to go trials
-The ventral striatum is the reward related region of the brain and showed a 3 way interaction of group x trial x emotion, with elevated activity to happy no go trials for low delayers relative to high delayers
What conclusions can be drawn from Casey’s study?
-Resistance to temptation appears to be a relatively stable characteristic of an individual over time
-Cognitive control can be strongly influenced by contextual factors (eg. hot cues) in alluring situations
-Ventral frontostriatal circuitry supports resistance to temptation, with a combination of lowered activity int he inferior frontal gyrus and increased activity in the ventral striatum in low delayers.
