Parkinson`s disease (PD) is associated with a range of cognitive impairments, most notably deficits of higher order cognitive control mechanisms referred to as "executive dysfunction". These problems have consistently been related to dysfunction of fronto-striatal circuitry (summary see Stocchi & Brusa, 2000). Executive function impairments may already be present in early stages of PD (Uekermann et al., 2004) and their severity may be exacerbated by affective changes such as depression (Uekermann et al., 2003). In addition to cognitive problems, PD patients frequently suffer from mood changes, in particular apathy (Kirsch-Darrow et al., 2006) and from affect processing impairments, relating to both the ability to decode the affective state of other people on the basis of facial expressions or prosody and to the ability to adequately express the patients` own emotions (e.g. Breitenstein et al., 1998; Zgaljardic et al., 2003, Pell & Leonard, 2005). The capacity for emotion perception was found to be linked to the severity of executive dysfunction; affective and cognitive changes are thus not independent, at least in patients with moderate PD (Breitenstein et al., 2001).