Limited behavioural repertoire impacts quality of life in chronic schizophrenia. 
We have previously shown that the amount of movement exhibited by patients with 
schizophrenia is positively correlated with the volume of left anterior 
cingulate cortex and that this quantity of movement can be increased by 
modafinil. However, increased movement in itself may be of limited clinical 
significance. Hence, we sought to analyse the 'structure' of spontaneous 
movement in patients with schizophrenia and to examine whether the chunking of 
spontaneous activity has a neuroanatomical basis. 'Actiwatches' were used to 
record spontaneous motor activity over a 20 hour period in sixteen male patients 
with schizophrenia. Time-series data were analysed for the number of discrete 
spontaneous activities, which might indicate a degree of structure to ongoing 
activity. Subjects underwent a whole-brain structural MRI scan. The 'number of 
discrete movement epochs' correlated with volumes of regions within bilateral 
rostro-ventral putamen and temporal poles. These data suggest that in people 
with schizophrenia the volume of bilateral putamen may influence the complexity 
of their behaviours, as distinct from the overall amount of behaviour. The 
results are presented in the context of a large body of previous research 
examining the role of the basal ganglia in motor and cognitive pattern 
generation.