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Electrophysiological and micro-stimulation studies in non-human animal species indicated that the superior colliculus (SC) plays a role in the control of upper limb movements. In our previous work we found reach-related signals in the deep superior colliculus in humans. Here we show that also signals in more dorsal locations are correlated with the execution of arm movements. We instructed healthy participants to reach for visual targets either presented in the left or in the right visual hemifield during an fMRI measurement. Visual stimulation was dissociated from movement execution using a pro- and anti-reaching task. Thereby, we successfully differentiated between signals at these locations induced by the visual input of target presentations on the one hand and by the execution of arm movements on the other hand. Extending our previous report, the results of this study are in good agreement with the observed anatomical distribution of reach-related neurons in macaques. Obviously, reach-related signals can be found across a considerable depth range also in humans., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The cortical systems involved in eye movement control in humans have been investigated extensively using fMRI. In contrast, there is virtually no data concerning the functional status of the human oculomotor brainstem nuclei. This lack of evidence has usually been explained by technical constraints of EPI based imaging and anatomical characteristics of the brainstem. Against this assumption, we successfully localised nuclei of the oculomotor system using high-resolution fMRI based on standard EPI sequences in a group of healthy subjects executing reflexive horizontal saccades. A random-effects group analysis revealed task-related BOLD increases in the superior colliculus, the oculomotor nucleus, the abducens nucleus and in the paramedian pontine reticular formation. This group analysis was complemented by individual positive findings in up to 94% of single subject analyses. A visual control paradigm led to increased signal levels in the superior colliculus consistent with its visual properties but no corresponding signal changes in other brainstem nuclei. These results are consistent with findings in animal studies and demonstrate the feasibility to detect BOLD signal increases associated with oculomotor tasks even in the human brainstem using conventional EPI imaging techniques., (Copyright © 2011 Elsevier Inc. All rights reserved.)