Cognitive and Tactile Factors Affecting Human Haptic Performance in Later Life

Background: Vision and haptics are the key modalities by which humans perceive objects and interact with their environment in a target-oriented manner. Both modalities share higher-order neural resources and the mechanisms required for object exploration. Compared to vision, the understanding of haptic information processing is still rudimentary. Although it is known that haptic performance, similar to many other skills, decreases in old age, the underlying mechanisms are not clear. It is yet to be determined to what extent this decrease is related to the age-related loss of tactile acuity or cognitive capacity. Methodology/Principal Findings: We investigated the haptic performance of 81 older adults by means of a cross-modal object recognition test. Additionally, we assessed the subjects ’ tactile acuity with an apparatus-based two-point discrimination paradigm, and their cognitive performance by means of the non-verbal Raven-Standard-Progressive matrices test. As expected, there was a significant age-related decline in performance on all 3 tests. With the exception of tactile acuity, this decline was found to be more distinct in female subjects. Correlation analyses revealed a strong relationship between haptic and cognitive performance for all subjects. Tactile performance, on the contrary, was only significantly correlated with male subjects ’ haptic performance. Conclusions: Haptic object recognition is a demanding task in old age, especially when it comes to the exploration o

Geomorfología y restauración fluvial: seguimiento del derribo de presas en Gipuzkoa

Se presenta la metodología diseñada para el seguimiento geomorfológico del derribo de azudes, así como los resultados obtenidos hasta el momento en dos casos concretos: las presas de Mendaraz (río Urumea) e Inturia (río Leitzaran) en Gipuzkoa. Se han realizado secciones transversales, abundantes mediciones de procesos sobre testigos, análisis de los nuevos depósitos generados y muestreos granulométricos y morfométricos. En el caso de Mendaraz se han registrado rápidas movilizaciones de sedimentos e importantes cambios geomorfológicos aguas arriba y abajo del obstáculo. Este proceso de recuperación de la dinámica fluvial natural y de regularización del cauce fue favorecido y acelerado por la crecida extraordinaria de noviembre de 2011. Además de sus beneficios para el estado ecológico, se ha constatado que el derribo de presas es una medida eficaz para la restauración de la dinámica geomorfológica en cauces fluviales. El seguimiento geomorfológico es una labor fundamental para cuantificar y valorar la dinámica generada a raíz del derribo de la presa y toda su evolución posterior. A methodology for dam removal monitoring and the results of two case studies is presented: Mendaraz dam (Urumea River) and Inturia dam (Leitzaran River), both located in Gipuzkoa. This monitoring is conducted by river survey cross-sections, measurements of processes and granulometrical analysis. Fast sediment erosion and sedimentation together with geomorphological adjustments were detected after dam removal. In Mendaraz an extraordinary flood favored these processes. The recovery of fluvial dynamics shows benefits not only from the ecological point of view but also for the restoration of natural river dynamics. Geomorphological monitoring is a key tool to quantify and assess river evolution and dynamics after dam removal

Mechanisms of tactile sensory deterioration amongst the elderly

It is known that roughness-smoothness, hardness-softness, stickiness-slipperiness and warm-cold are predominant perceptual dimensions in macro-, micro- and nano- texture perception. However, it is not clear to what extent active tactile texture discrimination remains intact with age. The general decrease in tactile ability induces physical and emotional dysfunction in elderly, and has increasing significance for an aging population. We report a method to quantify tactile acuity based on blinded active exploration of systematically varying micro-textured surfaces and a same-different paradigm. It reveals that elderly participants show significantly reduced fine texture discrimination ability. The elderly group also displays statistically lower finger friction coefficient, moisture and elasticity, suggesting a link. However, a subpopulation of the elderly retains discrimination ability irrespective of cutaneous condition and this can be related to a higher density of somatosensory receptors on the finger pads. Skin tribology is thus not the primary reason for decline of tactile discrimination with age. The remediation of cutaneous properties through rehydration, however leads to a significantly improved tactile acuity. This indicates unambiguously that neurological tactile loss can be temporarily compensated by restoring the cutaneous contact mechanics. Such mechanical restoration of tactile ability has the potential to increase the quality of life in elderly.