Disordered Brain Exam 2 - CS Function/Behavior

What is response bias?

Participants’ tendency to define ambiguous stimulus as target associated with more frequent reward.

Explain the behavioral experiment with faces/mouth and how that tests response bias/learning over time.

Participants are presented with faces, that can be either short mouth or long mouth. The faces are different, but only slightly, such that it is an ambiguous stimuli and it also is presented for only a short period of time (100 ms). But what researchers can do is differentially give reward for choosing either long mouth or short mouth correctly; if they choose long mouth correctly, they are more 3x as likely to recieve reward than if they choose short mouth correctly. This leads them to develop response bias over blocks of trials.

Is response bias learning present for people with depression?

No!

What activates the Ventral Striatum the most when predicting reward (showing the faces part)? What about when getting the reward feedback (getting money/reward)?

Whichever stimulus is the more frequent (long face if long face is more frequent reward)

Whichever stimulus is the less frequent (short face if long face is more frequent)

What is the pathway of goal directed planning?

dlPFC —> vmPFC —> VS

What is the action-initiation pathway?

VS —> Substantia Nigra —> DS —> DP —>Thalamus —> Motor cortices

What is the action-planning pathway?

VS —> Substantia Nigra —> DS —> dlPFC

What is the behavioral adjustment pathway? Go into it more in-depth with how dopamine is involved?

VS —> VP —> Thalamus —> vmPFC —> dACC —> dlPFC.

Normally, you go from VS to actions to goal achievement, which releases dopamine that then sends to VS again. When you don’t achieve goal via prior plan, no dopamine is released, and you go to the dACC (recognizing that goal isn’t being achieved) to dlPFC to come up with new plan.

Cue of sugar in tea lead to what activation? Is it stronger than when given the tea (the taste)?

Activates VS and OFC. It is stronger activation there for cue than the actual reward!

Pleasantness of texture (fattiness) and pleasantness of flavor is associated with what?

Greater pleasantness of both is correlated to stronger activation of VS and OFC.

People who had greater weight gain for the “Freshman 15” had:

Greater activity of the VS

When people see people that are more “attractive”, there is:

Greater activity of the VS

When people see sex (erotic film), there is:

Increased VS response

Cocaine infusion led to what activity patterns of the NAcc and Amygdala?

Greater activation of the NAcc, Lesser activation/deactivation of the amygdala

Ventral striatum is more associated with “wanting” or “liking?

It is most associated with the craving aspect, or the wanting.

Drug cues activate the:

VS, OFC, vmPFC

Pleasurable music leading to experience of chills elicits response of the:

VS

When music goes from neutral to pleasurable, there is an influx of ___________ to the ____________.

dopamine, NAcc/VS

What is the monetary incentive delay paradigm? Explain it.

It has two phases: Anticipation phase and Consumption phase. In the anticipation phase, people are presented with a cue that determines the type of trial, which can be either gain, neutral, or loss. The cue is usually a shape, with lines. The number of lines represents the magnitude of reward. For gain trial, if you press key fast enough after target is shown, you get reward, if not nothing happens. For loss trial, if you press key fast enough, you avoid losing money. For neutral trial, it doesn’t matter what you respond. There is a consumption phase where the participants are shown the results of their trial (i.e if they won money how much got added, what is their total prize pool). Scans of the brain occur during the delay between cue and target, during the target presentation, and during the outcome presentation.

For monetary incentive delay experiments, what is VS response most prominent to? What about OFC?

VS response is most prominent to the cue.

OFC response is most prominent to the feedback.

What is the card-guessing paradigm? Explain it.

Participants are shown the back of a card and told there are no face cards. They are asked to guess if the card is higher or lower than 5. The card is then turned over, and if guess is accurate, they win money, if not they lose money.

How does humor activate the CS circuit?

More funny activates the VS more.

How is trust related to CS circuit?

People who we trust more activates the VS more.

Explain the trust game.

You are decision maker 1, you can keep 10 out of 20 dollars or trust and pass decision to DM 2, who can either keep or share. If DM 2 shares, you get 20 they get 20. If DM 2 keeps, you get 0. Participants are randomly assigned to get either a cooperative DM 2, neutral DM 2, or uncooperative DM 2 for each trial. Over time, they are expected to learn what face is what type of behavior, although not told what partners are like.

Cooperative/more rewarding leads to _____________ VS response. BUT also when just shown the person, if they are cooperative, there is:

increased

increased VS response.

What are results of studies that look at pain of enemies? (Subjective ratings, neural activity, brain behavior)

Self reported pleasure for schadenfreude are significantly diff/higher when enemy is losing to another team.

When favored team succeeds or rival team fails against favored team, there is activation of VS and putamen. When favored team fails or rival team succeeds, ACC is activated.

VS/putamen is more active when pleasure ratings are higher and also when enemy is harmed (schadenfreude)

Explain shopping study: what three diff phases to look at brain activity?

First, show product, then show price, then show choice making, then chill till next. Show product and price is cue, just price is price differential, and choice = purchase.

There is __________ response in the VS for purchased items compared to not purchased items. In other words, the _________ the VS response, the more likely it is that the item is bought.

Greater!

Explain patient B-19, the experiment and what they aimed to do?

Patient was discharged from army because he was homosexual (considered disease back then) and temporal lobe epilepsy. They implanted electrodes in his NAcc area. He was put into a box and allowed to press button to stimulate the electrodes. He ended up self-stimulating a lot, and said that it caused feelings of pleasure, warmth, and alertness. Mainly, it evoked desire to press button again and never was substitute for sexual acts. Key is motivation to do behavior!

People who act more impulsive have ___________ activity in VS.

greater

Given two similar rewards, humans show a preference for the one that arrives _____________ rather than _____________.

sooner, later

What is delay discounting?

People tend to discount, or lower the value of a later reward depending on a factor that increases with length of delay.

Higher/steeper levels of delay discounting is correlated with _____________ activity of the ___________.

greater, VS