Biology subjects

Himmelbach, M.

Publications and source records attributed to Himmelbach, M..

3 recordsLinked to original sources

bioRxiv2023

The human superior colliculus motor region does not respond to finger movements

Electrophysiological studies in macaques and functional neuroimaging in humans revealed a motor region in the superior colliculus (SC) for upper limb reaching movements. Connectivity studies in macaques reported direct connections between this SC motor region and cortical premotor arm, hand, and finger regions. These findings motivated us to investigate if the human SC is also involved in sequential finger tapping movements. We analysed fMRI task data of 130 participants executing simple finger tapping from the Human Connectome Project (HCP). While we found strong signals in the SC for visual cues, we found no signals related to simple finger tapping. Assuming a differential effect owing to simple and complex finger tapping sequences, we searched for responses in the SC corresponding to complex finger tapping above simple finger tapping sequences. We observed expected signal differences in cortical motor and premotor regions, but our analyses provided no evidence for signals related to simple or complex finger tapping in the SC. Despite evidence for direct anatomical connections of the SC motor region and cortical premotor hand and finger areas in macaques, our results suggest that the SC is not involved in simple or complex finger tapping in humans.

neuroscience↗

bioRxiv2022

Activity in the human superior colliculus associated with reaching for tactile targets

The superior colliculus (SC) plays a major role in orienting movements of eyes and the head and in the allocation of attention. Functions of the SC have been mostly investigated in animal models, including non-human primates. Differences in the SCs anatomy and function between different species question extrapolations of these studies to humans without further validation. Few electrophysiological and neuroimaging studies in animal models and humans have reported an unexpected role of the SC in visually guided reaching movements. Using BOLD fMRI imaging, we sought to decipher if the SC is also active during reaching movements guided by tactile stimulation. Participants executed reaching movements to visual and tactile target positions. When contrasted against visual and tactile stimulation without reaching, we found increased SC activity with reaching not only for visual but also for tactile targets. We conclude that the SCs involvement in reaching does not rely on visual inputs. It is also independent from a specific sensory modality. Our results indicate a general involvement of the human SC in upper limb reaching movements.

neuroscience↗

bioRxiv2018

Effects of weight and height on hand selection: a low-cost virtual reality paradigm

The main objective was to evaluate the ability of a virtual reality (VR) system to reliably detect the so-called switch-point of a user; the distinguishing plane between free-choice use of the left and right hand. Independent variables of height and weight were incorporated into the study design and their effects on hand selection were analyzed. The paradigm utilized the Leap Motion Hand Tracker, along with a custom script written in C# and was realized through a Unity3D application. Stimuli appeared in random locations on the computer screen, and required the participant to reach with the hand of their choice to contact them with a virtual hand inside the virtual space. We observed main effects of height and weight on switch-points across the group. We found increased use of the dominant hand as stimuli height increased, as well as a significant increase in overall use of the dominant hand when a 500 gram weighted glove was worn by the non-dominant hand. We validated the average switch-points in VR as compared to real-world setups in previous studies. Our results are in line with previously published real-world data, supporting the use of this paradigm in future VR experiments and applications.

bioengineering↗