Biology subjects

Higgen, F. L.

Publications and source records attributed to Higgen, F. L..

4 recordsLinked to original sources

bioRxiv2020

Sensory capability and information integration independently predict cognitive status in healthy older adults

Ageing is characterized by changes in sensory and cognitive abilities. While there is evidence that decline in sensory acuity and enhanced multisensory integration predict cognitive status in healthy older adults, potential mechanistic links between these age-related alterations remain unclear. In the current study, we assessed performance of younger and older healthy adults in a visuotactile delayed match-to-sample task and related indices of multisensory integration to unisensory perceptual thresholds and cognitive assessment data. Additionally, we applied transcranial alternating current stimulation (tACS) to modulate cortical networks found to underlie visuotactile interactions and working-memory matching in our previous work. Analysing response times and signal detection measures, we found older adults to show enhanced multisensory integration and benefit more from successful working memory matching. Both measures predicted cognitive status and correlated positively with each other, suggesting that they likely reflect a common underlying tendency to integrate information. Sensory capability, however, independently predicted cognitive status. tACS with beta frequency (20 Hz) accelerated task performance and this effect was more pronounced in the older group. We conclude that sensory capability and information integration represent independent predictors of cognitive status. Finally, we discuss a potential role of the parietal cortex in mediating augmented integration in older adults.

neuroscience↗

bioRxiv2019

Crossmodal Pattern Discrimination in Humans and Robots: A Visuo-Tactile Case Study

The quality of crossmodal perception hinges on two factors: The accuracy of the independent unimodal perception and the ability to integrate information from different sensory systems. In humans, the ability for cognitively demanding crossmodal perception diminishes from young to old age.\n\nTo research to which degree impediments of these two abilities contribute to the age-related decline and to evaluate how this might apply to artificial systems, we replicate a medical study on visuo-tactile crossmodal pattern discrimination utilizing state-of-the-art tactile sensing technology and artificial neural networks. We explore the perception of each modality in isolation as well as the crossmodal integration.\n\nWe show that in an artificial system the integration of complex high-level unimodal features outperforms the comparison of independent unimodal classifications at low stimulus intensities where errors frequently occur. In comparison to humans, the artificial system outperforms older participants in the unimodal as well as the crossmodal condition. However, compared to younger participants, the artificial system performs worse at low stimulus intensities. Younger participants seem to employ more efficient crossmodal integration mechanisms than modelled in the proposed artificial neural networks.\n\nOur work creates a bridge between neurological research and embodied artificial neurocognitive systems and demonstrates how collaborative research might help to derive hypotheses from the allied field. Our results indicate that empirically-derived neurocognitive models can inform the design of future neurocomputational architectures. For crossmodal processing, sensory integration on lower hierarchical levels, as suggested for efficient processing in the human brain, seems to improve the performance of artificial neural networks.

neuroscience↗

bioRxiv2019

Reduced frontal white matter microstructure in healthy older adults with low tactile recognition performance

Aging leads to a reduction of connectivity in large-scale structural brain networks. Sensory processing and other cognitive processes rely on information flow between distant brain areas. However, data linking age-related structural brain alterations to cognitive functioning, especially sensory processing, is sparse.\n\nAiming to determine group differences in sensory processing between older and younger participants, we implemented a complex tactile recognition task and investigated to what extent changes in microstructural white matter integrity of large-scale brain networks might reflect success in task performance. Structural brain integrity was accessed by means of diffusion-weighted imaging and fractional anisotrophy.\n\nThe data revealed that poor performance in complex tactile recognition in older, neurologically healthy individuals is related to decreased structural integrity pronounced in the anterior corpus callosum. This region was strongly connected to the prefrontal cortex. Our data suggests decreased fractional anisotrophy in the anterior corpus callosum as a surrogate marker for progressed brain aging, leading to disturbances in networks relevant for higher-order cognitive processing. Complex tactile recognition might be a sensitive marker for identifying these starting cognitive impairments in older adults.

neuroscience↗

bioRxiv2019

Congruency effects can compensate for deficits of healthy older adults in crossmodal integration

One of the pivotal challenges of aging is to maintain independence in the activities of daily life. In order to adapt to changes in the environment, it is crucial to continuously process and accurately combine simultaneous input from different sensory systems, i.e., crossmodal integration.\n\nWith aging, performance decreases in multiple cognitive domains. The processing of sensory stimuli constitutes one of the key features of this deterioration. Age-related sensory impairments affect all modalities, substantiated by decreased acuity in visual, auditory or tactile detection tasks.\n\nHowever, whether this decline of sensory processing leads to impairments in crossmodal integration remains an unresolved question. While some researchers propose that crossmodal integration degrades with age, others suggest that it is conserved or even gains compensatory importance.\n\nTo address this question, we compared behavioral performance of older and young participants in a well-established crossmodal matching task, requiring the evaluation of congruency in simultaneously presented visual and tactile patterns. Older participants performed significantly worse than young controls in the crossmodal task when being stimulated at their individual unimodal visual and tactile perception thresholds. Performance increased with adjustment of stimulus intensities. This improvement was driven by better detection of congruent stimulus pairs (p<0.01), while detection of incongruent pairs was not significantly enhanced (p=0.12).\n\nThese results indicate that age-related impairments lead to poor performance in complex crossmodal scenarios and demanding cognitive tasks. Performance is enhanced when inputs to the visual and tactile systems are congruent. Congruency effects might therefore be used to develop strategies for cognitive training and neurological rehabilitation.

neuroscience↗