3/5/01, including ben's comments

Present: bdg, cad, dfk, dhl, sz

• Barry Lester - has huge NIDA grant for looking at cocaine addiction. Has been studying children from birth to watch development changes. Kids are 8 or 9 now, so going into adolescence. Brain prunes itself significantly at adolescence. May be able to use DT-MRI diff to track development changes. (Will there be any more cohorts? Ben thinks not. Unfortunate to have missed early development, but still some interesting pieces to come. Will probably need to follow normals to make this work, since there won' be a control group already imaged.)
• Steve Salloway studies dementia and degenerative diseases. Memory loss-inducing problems. Would like spectroscopy, but DT-MRI could work, too. White matter around ventricles have holes in them, thought to be fed by vessels that get infacted or are otherwise damaged. Compare to norms.
• Ben (and Steve Rasmussen) study folks in the middle of lifespan. OCD. Starts in childhood. E.g., can't go through a doorway. Cortex-basal ganglia-thalamus-orbitofrontal cortex loop involved. Pre and post gamma surgery changes in connectivity could be significant to visualize (See Dana proposal). Pre and post deep brain stimulation could also lead to changes, possibly, but might be more relevant to just understand exactly where the electrodes are, anatomically, in relation to fiber pathways connecting elements of the circuit involved.
• DBS work is proceeding. Don't know whether this disrupts activity, regularizes it, or stimulates it. Or what the pathways are. DT-MRI might be useful in delineating the anatomy in these patients. Gerhard Friehs is doing the DBS surgery. Ben has Brain Site stereotactic software/hardware-very similar to stereotactic guidance systems used clinically but in this form only approved for research - runs on a Mac. Might take a look at it to get ideas for what folks do for neurosurgery.
• Nucleus accumbens/ventral globus pallidus stimulated as a result of the targeting of the internal capsule (can we say this is fortuitous instead of accidental?) and seemed to be helpful.

  Serotonin-uptake inhibiting drugs (Prozac, Paxil, Zoloft, etc) are therapeutically useful in OCD. Ventral midline and structures nearby are all serotonin rich. [?? not sure what this is: All of the areas are ones that SSRI's help are same as ones that help OCD.

• NOTE DURING APPLICATION

• Should follow up with Carlo Pierpaoli to get pre- and post- gamma capsulotomy DT-MRI's. [Ben would help with this if needed. The first goal is to figure out how far from the gamma knife lesion we can see changes in the various pathways going through the anterior limb of the internal capsule. We think that the thalamus - cortex connections, which are reciprocal and excitatory, are the key, but there may well be others that are important in the therapeutic response. Any change we could see could be important.

• Need to deal with strength of anisotropy as well as directional/path changes.
• look at Brain Site software to study it for interface ideas. Perhaps give the group a demo.
• Looks like data from Hopkins starts too far posterior to see frontal orbital cortex. Get OCD data in the cave.
• Can't see bottom of brain because table is in the way underneath and ventricles are in the way on top.
• Get rid of a bunch of the data - how can we limit the field of view? lose top half lose left/right side choose some region to keep choose only tubes through some geometry (or through two geometries)
• Show brain supine (eyes up)
• lose ventricles entirely - with T2 slices, may be ok.
• When switching orientations, remember the slice you're on.
• Laser pointer needs to stop at geometry. This should be coordinated with picking for selecting geometric objects and for making them visible/invisible. (How do we get them back?)

• Resolution of slice looks very low. Perhaps the brain should be $100\%$ scale. Try that and current scale during next visit.
• Consider a threshold criterion based on how curved the tubes are?
• REALLY HAVE TO GET GAMMA DATA (OCD DATA) INTO THE CAVE!!! Use Peter Basser's brain for now? Do we have one of the real OCD datasets?

• Ben's followup suggestion: As we discussed, the ability to add the image elements (tubes, surfaces, ventricles) individually to the structural scans should really help us figure out whether we can image the anterior limb of the internal capsule, and of course, what the stream surfaces are. I've also attached the Dana grant (which is short!)(copied to /map/gfx0/common/diffusion/specs/docs/danagrant.doc) FYI.