VAN DEN BOS Wouter  STRIATUM Reward 8 Mar 2013

do you want a little money now  or
a lot of money in the future?

intertemporal choice...
find the indifference points... (at which it  makes no difference)

hyperbolic discounting of value
discount factor... how much do u discount future money

larger k means more impulsive...

eg for k = 0.05  30 bucks now would be worth
about 100 bucks in 1 year...

pros of this model:  fits data quite well
good model of drug addiction etc.

cons... it is NOT a cognitive model

(so, that's his objective)...
van den bos and (Sam) McClure  2013

might be difft networks involved...

eg an interplay btwn cognitive control and valuation/affect...

they argue that in their paper

impulsivity is char by steep discounting of delayed rewards...

as compared to 12 year olds... 25 year olds are more future oriented...

IQ and discounting are highly correl.
(ie the higher the IQ, the more you are willing to defer rewards)

comparing americans vs koreans...
americans are more impulsive

task:  do u want 10 dollars now or  20 bucks in 3 weeks  eg
then do fMRI...
asks a series of questions and finds indifference point...

<<<note to myself:  send jason yeatman  notes on josh sanes talk and also
re-ask Q abt theoret model of info in pathway: arcuate fascic>>

amygdala  and VMPFC light up with immediate  rewards...

<<<hot cognition vs cold/ analytic cogntion>>>

peper in 2012

cortico-striatal loops in intertemp choice

lower integrity within the frontostriatal tract
higher MD = mean diffus  and RD = radial diffus  and
 lower  FA  fractional anisotropy discounting...

*****

striatal connectivity patterns
haber and knutson in 2009

the frontal lobe connex are dominant: contrib 83% of volume of striatal  connex...

dorsal vs ventral striatum in tempor discounting...

neurons in the caudate nucleus  encoded diff btwn the options
(caudate is dorsal)
vs ventral  correl more with sum of the options...

ventral straitum... nuc accumbens eg

zimbo:  time perspective index
future orientation and present hedonism
ZTPI  zimbo temp perspective ...

task:  series of Qs... 10 bucks today or 27 bucks in 28 days  eg

estimate   k  (discount factor)
k ranges  from .004  to .11

and want to correl with  DTI data...

he always uses Log k  (rather than k)

present hedonism correl with Log K

versus  future orientation

future orientation..u can wait forever for the ten bucks...

striatal segmentation target

use ROIs  from AAL atlas...

seed regions  from L and R striatum..

probab:  total samples from voxel to target aarea
divided by total sample from that voxel to any area...

looks at most likely 5000 tracts for every voxel... see behrens  2007

this is FSL ProbTrackx

he is trying show  what  different segments of stratum are connected to
eg  to amygd  vs HC  vs mOFC  vs ACC vs PCC vs VLPFC vs LPFC vs DLPFC
vs  dACC vs SMA

more ventral areas are connect to amygdala and HC and OFC
more dorsal areas are connec to DLPFC and SMA

so   DLPFC  is correl with LESS impulsive

HC is in the middle

and amygdala and VLPFC are corr with mroe impulsive...

DLPFC  corr with LogK  is  r = -0.66
amygdala   has an r of 0.52  positive

HC  has an r = +0.4

VLPFC  r = -0.46

this slide  :  DLPFC abd VLPFC  have highest connectivity strength

result:  there is a dorsal ventral dichotomy in the data...

amygdala  shows +PPI   take the money now

vs  r DLPFC  interp  as downreg of striatum by dlpfc...

decision phase....

PPI is in expected direction

he tries to put this into a model

result  DLPFC mediates the effect on behavior...

future direcitons:
alternative measure of tract integrity
seed ROI striatal segments and target AAL ROIs

jay...  are these subjects around for behavioral study...(ie later on)
eg interested in knowing whether thiss correl with other behaviors...

he has 19 or 20 subjects...

this is a developmental population

FA, MD, and RD  measurements along tracts

jason yeatman; what  does connectivty measure mean  biologically?.