Proefschrift_Holstein

Chapter 2

compared with the previous trial, or switched. Finally, a reward cue at the start of each trial indicated whether €0.01 or €0.15 (or sometimes €0.10; chapter 5 ) could be earned after a correct and sufficiently fast response. Immediately following the response, feedback was given (e.g., “correct! 1 cent”). Responses (both behaviourally and neurally) on this task can be used to assess switching (by comparing switch to repeat trials), reward anticipation (by comparing high with low reward trials) and their interaction (i.e. low reward (switch – repeat) – high reward (switch – repeat). In addition, in chapter 7 this paradigm is used to assess the integration between reward, task switching and motor switching. This paradigm is used throughout this thesis to assess the effects of a dopamine receptor agonist ( chapter 3 ) on behaviour and to assess differences in neural signalling ( box 2.4 ) between patients with ADHD and the effects of methylphenidate ( box 2.2; chapter 4 ). Subsequently, it was used to investigatewhether performance on this task changes across the life span ( chapter 5 ). In chapter 6 I present a version of this paradigm designed for rodents to assess the causal role for the striatum ( box 2.5 ) in successful motivation-cognition integration. Finally, in chapter 7 I used non-invasive brain stimulation ( box 2.5 ) in human subjects to perturb activity in the neural circuitry involved in reward processing to gain insight in the neural mechanism underlying the reward, cognition, action integration.

TRIAL 1

TRIAL 2 low reward task switch response repeat

TRIAL 3 low reward task repeat response switch

TRIAL 4 high reward task switch response switch

reward cue

15 cent

1 cent

1 cent

15 cent

task cue

word

arrow

arrow

word

target

le

right

le

le

response

correct! 15 cent le

incorrect! 0 cent right

le

right

le

right correct! 1 cent

le

right

correct! 1 cent

incorrect! 0 cent

incorrect! 0 cent

correct! 15 cent

incorrect! 0 cent

feedback

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