Biology subjects

Giese, M.

Publications and source records attributed to Giese, M..

6 recordsLinked to original sources

bioRxiv2026

Rule-dependent transformation of observed into self-actions in macaque ventral premotor cortex

The ventral premotor cortex (PMv) has been implicated in both action selection and the perception of observed actions, but it remains unclear whether PMv activity during action observation reflects the observed action itself, or variables related to the observers own action when the observed action becomes behaviourally relevant. Here, we recorded neural activity in macaque PMv during a task that dissociated observed action, rule context, and the subsequently selected self-action. Population activity during observation was already biased toward the upcoming self-action and became increasingly aligned with it. At the level of single neurons, subsets showed modulation by rule and required self-action beyond the observed action. Task-related variables coexisted during observation, rather than being organized into distinct sequential stages. These findings indicate that PMv activity during action observation is not solely determined by the observed action, but instead reflects variables related to the selection of the agents own action, consistent with a transformation from observed action to self-action.

neuroscience↗

bioRxiv2026

Behavioral evidence challenges species-specific ocular morphology as a primary constraint on human gaze-following

Previous research suggests that humans are extremely sensitive to object-directed eye gaze, which effectively guides their attention toward objects of shared interest. This contrasts with non-human primates, who typically require much more salient eye-gaze cues to achieve comparable attentional orienting. However, it remains unclear whether cross-species differences in ocular morphology account for this performance gap. To address this question, we examined humans covert shifts of spatial attention in response to eye-gaze cues provided by either realistic human or rhesus monkey head avatars. Target detection was reliably enhanced on gaze-congruent compared to gaze-incongruent trials, with comparable gaze-cueing effects for both avatar types, despite the fact that monkey eyes lack many of the conspicuous features characteristic of human eyes. Hence, eye morphology alone does not substantially modulate gaze-driven attentional orienting in humans, whereas humans reliable use of monkey eye-gaze cues highlights a clear species difference in perceptual sensitivity to eye gaze signals. Significance StatementEye-gaze-mediated attentional orienting is a conserved ability across primates, yet sensitivity to subtle eye-gaze cues may differ between species. Here, we provide empirical evidence that humans exhibit a quantitatively greater capacity than non-human primates to follow subtle eye-gaze cues. Importantly, we showed that this difference cannot be attributed to species-specific ocular morphology as human participants showed robust and comparable reflexive attentional orienting to both human and rhesus monkey eye-gaze cues. This is striking given the pronounced differences in ocular morphology and coloration/contrast between the two species. These findings suggest that cross-species diversity in extracting spatial information from eye-gaze cues likely reflects differences in perceptual sensitivity rather than bottom-up constraints imposed by species-specific ocular morphology.

neuroscience↗

bioRxiv2024

Staphylococcus aureus lipid factors modulate melanoma clustering and invasion in zebrafish

The microbiome can influence cancer development and progression. However, less is known about the role of the skin microbiota in melanoma. Here, we take advantage of a zebrafish melanoma model to probe the effects of Staphylococcus aureus on melanoma invasion. We find that S. aureus produces factors that enhance melanoma invasion and dissemination in zebrafish larvae. We used a published in vitro 3D cluster formation assay which correlates increased clustering with tumor invasion. S. aureus supernatant increased clustering of melanoma cells which was abrogated by use of a Rho-Kinase inhibitor, implicating a role for Rho-GTPases. The melanoma clustering response was specific to S. aureus and not other staphylococcal species, including S. epidermidis. Our findings suggest that S. aureus may promote melanoma clustering and invasion via lipids generated by the lipase SAL2 (gehB). Taken together, these findings suggest that specific bacterial products mediate melanoma invasive migration in zebrafish. Summary statementS. aureus supernatant increases melanoma invasion in zebrafish and is likely mediated by production of bacterial lipids.

cancer biology↗

bioRxiv2023

PTP1B phosphatase puts a brake on iPSC-derived neutrophil motility and antimicrobial function

Neutrophils are rapidly recruited to sites of infection and are critical for pathogen clearance. Neutropenic patients are at high risk for fungal and bacterial infections and can benefit from granulocyte transfusion therapy. Human induced pluripotent stem cells (iPSCs) could provide a robust source of neutrophil-like cells for infusion as they can be generated in large quantities and do not require a donor. However, dampened intracellular signaling limits their cellular activation and response. Here, we show that we can engineer iPSC-derived neutrophils (iNeutrophils) for enhanced motility and anti-microbial functions. Deletion of the PTP1B phosphatase increased iNeutrophil PI3K and ERK signaling and was associated with increased F-actin polymerization, cell migration and phagocytosis. PTP1B deletion also increased production of inflammatory cytokines, including the neutrophil chemoattractant IL-8. Furthermore, PTP1B-KO iNeutrophils displayed a highly activated morphology and were more responsive to the fungal pathogen Aspergillus fumigatus. KO iNeutrophils efficiently migrated to and swarmed hyphae resulting in inhibition of fungal growth. Taken together, deletion of the PTP1B phosphatase removes the "brakes" on iPSC-derived intracellular signaling and neutrophil function. Key pointsDeletion of PTP1B increases iPSC-derived neutrophil intracellular signaling to improve motility and phagocytosis. Deletion of PTP1B enhances iPSC-derived neutrophil swarming response and ability to inhibit fungal growth.

immunology↗

bioRxiv2022

A large-scale brain network of species-specific dynamic human body perception

This ultrahigh field 7T fMRI study addressed the question of whether there exists a core network of brain areas at the service of different aspects of body perception. Participants viewed naturalistic videos of monkey and human faces, bodies, and objects along with mosaic-scrambled videos for control of low-level features. ICA-based network analysis was conducted to find body and species modulations at both the voxel and the network levels. Among the body areas, the highest species selectivity was found in the middle frontal gyrus and amygdala. Two large-scale networks were highly selective to bodies, dominated by the lateral occipital cortex and right superior temporal sulcus (STS) respectively. The right STS network showed high species selectivity, and its significant human body-induced node connectivity was focused around the extrastriate body area (EBA), STS, temporoparietal junction (TPJ), premotor cortex, and inferior frontal gyrus (IFG). The human body-specific network discovered here may serve as a brain-wide internal model of the human body serving as an entry point for a variety of processes relying on body descriptions as part of their more specific categorization, action, or expression recognition functions.

neuroscience↗

bioRxiv2019

Rigid Foot Soles Improve Balance in Beam Walking

Maintaining balance while walking on a narrow beam is a challenging motor task. This is presumably because the foots ability to exert torque on the support surface is limited by the beam width. Still, the feet serve as a critical interface between the body and the external environment, and it is unclear how the mechanical properties of the feet affect balance. Here we examined how restricting the degrees of freedom of the feet influenced balance behavior during beam walking. We recorded whole-body joint kinematics of subjects with varying skill levels as they walked on a narrow beam with and without wearing flat, rigid soles on their feet. We computed changes in whole-body motion and angular momentum across these conditions. Results showed that wearing rigid soles improved balance in the beam walking task, but that practice with rigid soles did not affect or transfer to task performance with bare feet. The absence of any after-effect suggested that the improved balance from constraining the foot was the result of a mechanical effect rather than a change in neural strategy. Though wearing rigid soles can be used to assist balance, there appear to be limited training or rehabilitation benefits from wearing rigid soles.

neuroscience↗