Disordered Brain Exam 2 - CS MDD and BIP

What is the important aspect of MDD that is implicated via the CS circuit?

Anhedonia, or the absence of interest or pleasure for activities/other stuff.

What are the key takeaways from the experiment where healthy controls or MDD patients were given picture cues that cued water intake while they were restricted from water? What is the interpretation?

Reduced reactivity of the VS in response to cues for MDD patients.

Increased reactivity of the VTA in response to cues for MDD patients.

MDD is not about a problem with learning. The VTA is trying to send dopamine to the VS to open it, but the VS just isn’t opening. Usually, the VS gate opens and becomes active in response to cues for reward, but in MDD it doesn’t, which can explain anhedonia.

What are the key takeaways on studies of the monetary incentive delay paradigm on MDD patients vs. healthy controls? For the reward anticipation (cue) vs. reward outcome (getting reward)?

For reward anticipation, or to cues in the MIDT, there is both null findings (no diff between MDD and controls) and a decreased response (hypoactivity) for the putamen.

For reward outcome, or to results in MIDT, there is less activity (hypoactivity) of the mPFC, putamen, insula, VS, and caudate for gain trials only!

What are the key takeaways on studies of the card guessing task on MDD patients vs. healthy controls? For reward outcome (getting reward)?

MDD patients have lower activity (hypoactivity) of the VS in response to reward outcome.

What does medication do for helping MDD patients? What activity does it return to “normal”? What does CBT affect?

Medications increase ventral striatum response to both gains and losses in the MIDT for reward cues!

CBT increases activation of the mPFC and dorsal striatum responses to reward cues.

When presented with different words that have different valences (positive, neutral, or negative), what do MDD patients show for subjective ratings? What about for CS activity?

Subjective ratings: negative words are rated as more negative, and better memory for these negative words.

Hypo-reactivity of the VS for positive words only!

_____________ VS response to reward at baseline predicts reduced anhedonia for those going through treatment.

Greater

What is DBS? What does it accomplish?

Deep Brain Stimulation is a treatment for MDD patients which have tried antidepressant medications and CBT to no avail. They have surgically implanted electrodes in the brain, specifically the VS area. These electrodes periodically send electrical impulses to this region to activate it, and it does seem to increase VS activity! It also seems to reduce symptoms of MDD!

Summarize the key levels of activity for the CS in Bipolar Patients, and in response to what phase of Bipolar disorder?

For Bipolar Disorder patients in the euthymic phase, there is conflicting literature.

For BPD patients in the manic phase, there is hypo-reactivity of the VS for low magnitude rewards only for reward anticipation. There is also hyposensitivity of the VTA for reward anticipation and hyposensitivity of the VS for reward outcome. Hyposensitivity meaning that normally, you would have greater activity of the VTA and VS to reward compared to no reward for MIDT, but that is absent for manic phase BPD.