The free choice whether or not to respond after stimulus presentation.
The concept of 'willed' actions has attracted attention during the last few years. Free choices have been associated with activations on the medial frontal surface, the dorsolateral prefrontal cortex and the parietal lobe. Self-paced movements and free selection between various motor responses were typically used to investigate voluntary behavior. The aim of the present study was to determine neural correlates of voluntary motor responses and the voluntary inhibition of motor responses in a group of healthy subjects. Hence, a go/nogo/voluntary selection paradigm was used. In the voluntary selection condition subjects decided freely whether or not to respond with a button press after stimulus presentation. Functional MRI data and event-related potentials were acquired simultaneously in order to reliably investigate spatial and temporal characteristics of these responses. The results showed decision-related enhanced neural responses predominantly in the medial frontal gyrus/supplementary motor area, lateral frontal brain regions and the inferior parietal gyrus. Additional activations associated with voluntary movements were detected in the frontal eye field as well as brain regions directly linked to motor responses (e.g. somatosensory cortical areas). Altogether, decision processes were shown to be relatively independent of the kind of response chosen.
Karch
Susanne
S
Department of Psychiatry and Psychotherapy, Ludwig-Maximilians University Munich, Munich, Germany. susanne.karch@med.uni-muenchen.de
Mulert
Christoph
C
Thalmeier
Tobias
T
Lutz
Jürgen
J
Leicht
Gregor
G
Meindl
Thomas
T
Möller
Hans-Jürgen
HJ
Jäger
Lorenz
L
Pogarell
Oliver
O
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology; D002755:Choice Behavior / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009068:Movement / Q000502:physiology*; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D014836:Volition / Q000502:physiology*; D055815:Young Adult