The Corticostriatal Circuit: Disorder Flashcards
what is ADHD?
(VS hypoactivity)
constellation of symtoms: attention deficit, hyperactivity, impulsivity
*more often diagnosed in boys than girls
STUDY: MIDT w ADHD
VS hypoactivity in anticipation of reward
lower VS activity = greater symptom severity
STUDY: Marshmallow task w ADHD
during anticipation when delay: lower DS activity (overall)
WHY? may occur because no regulation of VS leading to hyperactivity and impulsivity
STUDY: ADHD and impulsivity
greater DS activity and hyperactivity w ADHD
WHY? may be a failure of VS gate activation in anticipation of a rewarding stimuli
integrating ADHD into the model
(taking operant conditioning, execution of plan model)
- lower VS activation, greater DS activation, more movement
(DS acts independently of the VS because DS hyperactivity even itf hypoactivity of VS)
ADHD and predicting shift of cues
lower VS activity based on symptom severity (not able to shift from reward to cues that predict reward)
Dopamine transfer deficit hypothesis (DTD hypothesis)
altered firing of dopamine in response to a cue
normal dopamine activity vs. DTD
normally: dopamine during unexpected reward, dopamine activity during cue and reward, eventually just dopamine release during cue
DTD: hyperactivity/ impulsivity may emerge from a failure of DA to transfer to cues
what does aderall do?
floods the system with dopamine
what is conduct and antisocial personality disorder?
(VS hyperactivity)
STUDY: MIDT and ASPD
VS hyperactivity in anticipation of reward
greater VS activity associated with antisocial behavior
greater DA activity
ADHD and ASPD on a spectrum
bell curve
ADHD on the left (hyperactivity of VTA/ VS)
ASPD on the right (hypoactivity of VTA/ VS)
STUDY: Mendota Medical Treatment Center for Incarcerated Kids
(if retain good points, get to do more good things)
capitalize on their sensitivity to reward, don’t respond well to punishment
What is MDD?
(VS hypoactivity)
another contributor is anhedonia (the absence of pleasurable experiences)
STUDY: MIDT and MDD
no major difference in VS activation
(3rd time they conducted this study, found lower VS activity)
STUDY: looking at happy expressions
greater amygdala activity to sad expressions in MDD
STUDY: reading and rating words
(rated positive, neutral, and negative words)
FIND: individuals with depression found less VS activity to positive words (correlated with anhedonic symptoms)
STUDY: meta analysis of kids and activation of VS across time
hypoactivity in onset of depression
- blunted positive response to reward as kids can be a pathway to depression
Treatment of MDD in kids
greater baseline VS response in kids –> greater likelihood activation therapy works
pharmacological treatments
(on SSRI for 6 weeks)
before treatment: hypo VS activity
post-treatment: hyper VS activity (associated with symptom improvement)
*magnitude of VS activation predicts positivity of symptoms
DBS surgery
through a study showing impact of stimulation on and off, symptom severity much lower after DBS surgery and stimulation
*unclear if targeting of VS of vmPFC is better
STUDY: resilience
(study of college students who recently experienced a lot of stressors)
- if have lower VS activity as you’re experiencing more stressors low positive affect (only experience this if have lower VS activity to reward)
what is PTSD?
(VS hypoactivity)
internalizing disorder
*recall
STUDY: Israeli solders & PTSD
(bottom right quadrant) greater response to threat and lower response to reward –> most severe case of PTSD
- may reflect an inability to maintain a positive affect in stressful times
what are eating disorders?
(VS hyperactivity)
STUDY: MIDT & eating disorders
*not super useful to study this way bc more about perception
don’t respond to food reward in the same way
STUDY: body image
(given compilation of images of bidy mass, 8 different ones, labeling as under/ normal/ overweight)
(guess weight & decide how image makes you feel about yourself
STUDY: body image
“what is this person’s weight?”
Pretty accurate
*shows its not about abnormal perception, just abnormal motivation
STUDY: body image
“how would you feel if you were this weight?”
very good: underweight
very bad for normal & overweight
(in anorexia nervosa people)
- greater VS activity in viewing underweight bodies
- lower VS activity in viewing overweight bodies
anorexia nervosa
(AN)
distorted body image, excessive dieting –> sever weight loss, pathological fear of being fat
bulimia nervosa
(BN)
severe weight gain fear, maintain normal weight through binge eating and purging cycles
STUDY: food preference
general preference for low calorie, low-fat food
dlPFC acts on DS
IN BRAIN:
- low calorie food choice: activation in DS caudate, stronger signals = stronger preference
- greater functional connectivity between dlPFC and DS in women with BS when choice for low calorie mag correlate with amount of food eaten the next day
substance use disorder cycle (addiction)
intoxication –> bingeing –> withdrawal –> craving –>
why does addiction develop?
drugs can open the VS gate through direct release of the DA key –> drug “high” (drug activation of ‘hedonic hot spots’ in VS and VP)
intoxication
(primary reinforcer) goal-directed
greater VS activation with great intoxication
Craving
(secondary reinforcer) cues of drug abuse
- elicit reaction in VS activation
- ex. drug paraphernalia, flavor of alcohol, aroma of alcohol etc. are all cues that lead to craving and drug seeking behavior
what is considered a drug?
its not just chemical/ natural
also gaming & gambling addiction (VS activation)
internet & social media addiction
withdrawal & bingeing
withdrawal: if don’t get drug symptoms –> withdrawal and craving
bingeing: tolerance increases as you continue to use the drug, leading to having to take more to elicit the same feeling
STUDY: GDNF gene therapy for alcohol use disorder
(had cats addicted to alcohol when they introduced the gene)
able to experience abstinence for 12 months because of greater DA functioning
(to rehabilitate DA functioning)
What is obesity?
a form of addiction
similar striatum activation to cocaine users (maybe consumption of high calorie foods can act on DA pathway and change amount released)
STUDY: high fat biases hypothalamic and mesolimbic
(if feed high-calorie and fat diet to mice, they can’t eat/ crave standard food)
Preventing obesity
- obesity lowers as consumption of calorie-rich food and VS activation increase
- greater VS activity during anticipation (seeking greater calorie foods) but not recovery (lower VS activation during consumption –> overeating)
What is the biggest predictor of developing pathology?
family history
amygdala and fam history
may affect drug addiction and fam history
- greater percent signal change
VS reactivity vs. amygdala reactivity
high VS, low amygdala: greater positive family history = blunted amygdala response to threat –> pathway to drinking through pathway of greater impulsivity and threat response
low VS, high amygdala: greater problem with alcohol use when stressed out –> mediated by anxiety and greater amygdala reaction to threat, lower VS
amygdala and fam history?
maybe association between goal-fear directed behavior and alcohol addiction w fam history
STUDY: problematic alcohol consumption among college students
low VS activity: lower drive, higher sensitivity to threat
high VS activity: higher drive to pursuit reward
