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Fig. 1 | Neurological Research and Practice

Fig. 1

From: Neurobiology and clinical features of impulse control failure in Parkinson’s disease

Fig. 1

a Scheme of the reward valuation network as derived from a neuroimaging study by Camara et al. [11] (orange boxes, black arrows) embedded in a wider motivation/learning circuit (gray boxes and arrows). The wider network is based on Kelley et al. (2004), omitting unspecific hypothalamic/thalamic projections. b Model of intertemporal choice behavior as proposed by Volkow and Baler [93]. The regions colored in red are considered to support decisions for later, larger rewards (“LATER”), whereas the green areas support decisions for immediately available rewards (“NOW”). Regions depicted in blue modulate intertemporal choice behavior by integrating different information (described in black lettering). Please note, that tonic dopamine (DA) signals are thought to favor LATER rewards by influencing frontal regions. By contrast, phasic DA signals drive decisions towards choosing the immediately available reward (NOW). Regions: dorsolateral prefrontal cortex (dlPFC), medial PFC (mPFC), ventromedial PFC (vmPFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), nucleus accumbens (NAcc). c Illustration of the role of phasic and tonic dopaminergic projections (after [32]): The Nacc serves as an integrator of afferent inputs from frontal and limbic regions. Of note, the input from the PFC is regulated by dopaminergic input from VTA via presynaptic D2 receptors, with D2 receptor stimulation resulting in an inhibition of PFC input to the Nacc. The presynaptic neurons are stimulated by tonic dopamine neuron firing leading to low tonic levels of dopamine. High-amplitude, phasic dopamine signals on the other hand lead to D1 receptor activation that potentiates the hippocampal input to the NAcc

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