Biology subjects

Rennig, J.

Publications and source records attributed to Rennig, J..

5 recordsLinked to original sources

bioRxiv2021

The role of posterior ventral stream areas for viewpoint-invariant object recognition

Object constancy is one of the most crucial mechanisms of the human visual system enabling viewpoint invariant object recognition. However, the neuronal foundations of object constancy are widely unknown. Research has shown that the ventral visual stream is involved in processing of various kinds of object stimuli and that several regions along the ventral stream are possibly sensitive to the orientation of an object in space. To systematically address the question of viewpoint sensitive object perception, we conducted a study with stroke patients as well as an fMRI experiment with healthy participants applying object stimuli in several spatial orientations, for example in typical and atypical viewing conditions. In the fMRI experiment, we found stronger BOLD signals and above-chance classification accuracies for objects presented in atypical viewing conditions in fusiform face sensitive and lateral occipito-temporal object preferring areas. In the behavioral patient study, we observed that lesions of the right fusiform gyrus were associated with lower performance in object recognition for atypical views. The complementary results from both experiments emphasize the contributions of fusiform and lateral-occipital areas to visual object constancy and indicate that visual object constancy is particularly enabled through increased neuronal activity and specific activation patterns for objects in demanding viewing conditions.

neuroscience↗

bioRxiv2020

Neural correlates of imaging biomarkers for primary motor deficits after stroke - more than just the primary motor system?

Hemiparesis is a common consequence of stroke to the primary motor system. Previous studies suggested that damage to additional brain areas might play a causal role in the occurrence and severity of hemiparesis and its recovery. Knowledge of these regions might be applied in the creation of imaging biomarkers for motor outcome prediction if lesion information from such areas carries predictive value. We assessed acute and chronic paresis of the upper limb in 102 patients with unilateral stroke. In a first experiment, the neural correlates of acute and chronic upper limb paresis were mapped by lesion behaviour mapping. Following the same approach, a lesion biomarker of corticospinal tract (CST) damage was mapped. This analysis served as an artificial control condition as the biomarker, by definition, is only causally related to damage of the CST. Mapping acute or chronic upper limb paresis implicated areas outside of the primary motor system. Likewise, mapping the CST lesion biomarker implicated several areas outside of the CST with high correspondence to areas associated with upper limb paresis. Damage to areas outside of the primary motor system thus might, to some degree, not play a causal role in hemiparesis. In a second experiment, we showed that lesion information from these areas outside of the primary motor system can be used to predict motor outcome. This was even the case for the CST lesion biomarker. Although the only causal source underlying the CST lesion biomarker was damage to the CST, lesion information that mainly included non-CST regions was able to predict the biomarker (non-significantly) better than information taken from only the CST itself. These findings suggest that simple theory-based biomarkers or qualitative rules to infer post-stroke outcome from imaging data might perform sub-optimally, as they do not consider the complexity of lesion data. Instead, high-dimensional models with data-driven feature selection strategies might be required.

neuroscience↗

bioRxiv2020

Temporo-parietal brain regions are involved in higher order object perception

Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical ( non-canonical) orientation. In a localizer experiment, we identified individual temporoparietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions. HighlightsO_LIPosterior temporo-parietal brain areas in the TPJ region that are involved in global shape perception are significantly involved in object perception C_LIO_LIIndividual global shape TPJ ROIs identified with a specific localizer experiment prefer objects in non-canonical over objects in canonical orientations C_LIO_LIUnivariate activations and multivariate voxel patterns in global shape TPJ ROIs distinguish canonical and non-canonical object presentations C_LI

neuroscience↗

bioRxiv2020

Linking Activity in Human Superior Temporal Cortex to Perception of Noisy Audiovisual Speech

Regions of the human posterior superior temporal gyrus and sulcus (pSTG/S) respond to the visual mouth movements that constitute visual speech and the auditory vocalizations that constitute auditory speech. We hypothesized that these multisensory responses in pSTG/S underlie the observation that comprehension of noisy auditory speech is improved when it is accompanied by visual speech. To test this idea, we presented audiovisual sentences that contained either a clear auditory component or a noisy auditory component while measuring brain activity using BOLD fMRI. Participants reported the intelligibility of the speech on each trial with a button press. Perceptually, adding visual speech to noisy auditory sentences rendered them much more intelligible. Post-hoc trial sorting was used to examine brain activations during noisy sentences that were more or less intelligible, focusing on multisensory speech regions in the pSTG/S identified with an independent visual speech localizer. Univariate analysis showed that less intelligible noisy audiovisual sentences evoked a weaker BOLD response, while more intelligible sentences evoked a stronger BOLD response that was indistinguishable from clear sentences. To better understand these differences, we conducted a multivariate representational similarity analysis. The pattern of response for intelligible noisy audiovisual sentences was more similar to the pattern for clear sentences, while the response pattern for unintelligible noisy sentences was less similar. These results show that for both univariate and multivariate analyses, successful integration of visual and noisy auditory speech normalizes responses in pSTG/S, providing evidence that multisensory subregions of pSTG/S are responsible for the perceptual benefit of visual speech. Significance StatementEnabling social interactions, including the production and perception of speech, is a key function of the human brain. Speech perception is a complex computational problem that the brain solves using both visual information from the talkers facial movements and auditory information from the talkers voice. Visual speech information is particularly important under noisy listening conditions when auditory speech is difficult or impossible to understand alone Regions of the human cortex in posterior superior temporal lobe respond to the visual mouth movements that constitute visual speech and the auditory vocalizations that constitute auditory speech. We show that the pattern of activity in cortex reflects the successful multisensory integration of auditory and visual speech information in the service of perception.

neuroscience↗

bioRxiv2018

Face Viewing Behavior Predicts Multisensory Gain During Speech Perception

During face viewing, some individuals prefer to fixate the mouth while others fixate the eyes. Individuals who have a history of mouth fixation might have stronger associations between visual and auditory speech, resulting in improved comprehension. First, we measured eye movements during face-viewing and observed high interindividual variability in mouth fixation time. Next, we measured eye movements and comprehension during perception of noisy auditory speech with or without visual speech. When visual speech was present, participants primarily fixated the mouth, but derived substantial benefit compared to noisy auditory speech with high interindividual variability. The benefit of visual speech was predicted by the eye movements made during the initial face-viewing task, but not by eye movements during the noisy speech task. These findings suggest a link between eye movements during face viewing and audiovisual speech perception and suggest that individual histories of visual exposure shape abilities across cognitive domains.

neuroscience↗