Humans and many animals prefer immediate over delayed rewards. This
de-valuation of rewards with increasing delay is referred to as temporal
discounting, a phenomenon reliably associated with a range of
problematic behaviours, including drug use, gambling addiction and
obesity. Temporal discounting is sensitive to modulation, e.g. by cueing
participants to use prospection (i.e. detailed imaginations of the
future) during decision-making. The gold standard to measure individual
differences in prospection is based on variations of the
Autobiographical Memory Interview, but it is unclear whether such
individual differences relate to temporal discounting, or whether steep
discounting in addiction is related to prospection impairments.
In the first part of my talk, I will show behavioural data exploring the
association between temporal discounting and measures of episodic
prospection ability (based on the Autobiographical Memory Interview) in
healthy adolescents, healthy adults and patients with gambling
addiction. If time permits I will then also show some more quantitative
analyses of Autobiographical Memory Interview data using tools from
quantitative text analysis that we have been working on recently. I will
then show behavioural and neuroimaging evidence for a similar modulation
of choice behavior in gambling addiction and controls via the use of
episodic prospection.

In the second part of my talk I will turn to the role of the prefrontal
cortex in temporal discounting and model-based choice behavior using
behavioural analyses in patients with focal prefrontal cortex lesions.
OFC damage has traditionally been associated with increases in
impulsivity, but the underlying processes are still unclear. I will show
data suggesting that OFC damage indeed increases discounting, but leaves
performance on a two-step decision-task typically used to measure
model-based decision-making largely intact. However, patients
additionally showed impairments in reward sensitivity, which correlated
with discounting behavior. These preliminary data suggest that increases
in temporal discounting following damage to OFC may at least in part be
attributable to reduced reward sensitivity.