Changes in Head Stability Control in Response to a Lateral Perturbation while Walking in Older Adults

Falling is a main contributor of injury in older adults. The decline in sensory systems associated with aging limits information needed to successfully compensate for unexpected perturbations. Therefore, sensory changes result in older adults having problems maintaining balance stability when experiencing an unexpected lateral perturbation (e.g. slip) in the environment. The goal of this study was to determine head stability movement strategies used by older adults when experiencing an unexpected lateral perturbation during walking. A total of 16 healthy adults, aged 66-81 years, walked across a foam pathway 6 times. One piece of the foam pathway covered a movable platform that translated to the left when the subject stepped on the foam. Three trials were randomized in which the platform shifted. Angular rate sensors were placed on the center of mass for the head and trunk segments to collect head and trunk movement in all three planes of motion. The predominant movement strategies for maintaining head stability were determined from the results of the cross-correlation analyses between the head and trunk segments. The Chi square test of independence was used to evaluate the movement pattern distributions of head-trunk coordination during perturbed and non-perturbed walking. When perturbed, head stabilization was significantly challenged in the yaw and roll planes of motion. Subjects demonstrated a movement pattern of the head leading the trunk in an effort to stabilize the head. The older adult subjects used this head stabilization movement pattern to compensate for sensory changes when experiencing the unexpected lateral perturbation

IMPLICACIONES PARA EL ESTUDIO DE LA NEUROBIOLOGÍA DE LA EXPERIENCIA CONSCIENTE. EL ACTO IMPULSIVO

Conciencia e impulsividad son dos constructos multidimensionales relacionados con el control del pensamiento y comportamiento humano. Impulsividad es un rasgo de personalidad complejo caracterizado por una elevada tendencia a actuar sin pensar, incapacidad para planear actividades futuras y disminución de la capacidad de concentración. Conciencia por su parte, es un constructo que cobija una serie de procesos fisiológicos relacionados con la generación de experiencia conciente y la adquisición de conocimientos. Con respecto al control sobre la acción humana, conciencia e impulsividad parece estar relacionados con comportamientos opuestos. Históricamente, los esfuerzos realizados por diversas disciplinas con el fin de estudiar estos constructos han llevado al desarrollo de definiciones divergentes y a una serie de medidas, causando una mayor confusión. Los propósitos de este artículo son: 1) describir ejemplos de posibles soluciones al estado de confusión en el campo de la investigación sobre impulsividad y discutir como el estudio de la conciencia puede beneficiarse de la investigación de la impulsividad; 2) discutir algunas de las maneras utilizadas para medir impulsividad en el laboratorio y cómo hacer de estos constructos variables experimentales; 3) resumir algunas de las lecciones derivadas de la comparación de los actos impulsivos con los premeditados desde una perspectiva integral y multidimensional; 4) discutir las implicaciones derivadas del uso de un enfoque multidimensional para el estudio de la conciencia

Implicaciones para el estudio de la neurobiología de la experiencia consciente: el acto impulsivo

Conciencia e impulsividad son dos constructos multidimensionales relacionados con el control del pensamiento y comportamiento humano. Impulsividad es un rasgo de personalidad complejo caracterizado por una elevada tendencia a actuar sin pensar, incapacidad para planear actividades futuras y disminución de la capacidad de concentración. Conciencia por su parte, es un constructo que cobija una serie de procesos fisiológicos relacionados con la generación de experiencia consciente y la adquisición de conocimientos. Con respecto al control sobre la acción humana, conciencia e impulsividad parece estar relacionados con comportamientos opuestos. Históricamente, los esfuerzos realizados por diversas disciplinas con el fin de estudiar estos constructos han llevado al desarrollo de definiciones divergentes y a una serie de medidas, causando una mayor confusión. Los propósitos de este artículo son: 1) describir ejemplos de posibles soluciones al estado de confusión en el campo de la investigación sobre impulsividad y discutir como el estudio de la conciencia puede beneficiarse de la investigación de la impulsividad; 2) discutir algunas de las maneras utilizadas para medir impulsividad en el laboratorio y cómo hacer de estos constructos variables experimentales; 3) resumir algunas de las lecciones derivadas de la comparación de los actos impulsivos con los premeditados desde una perspectiva integral y multidimensional; 4) discutir las implicaciones derivadas del uso de un enfoque multidimensional para el estudio de la conciencia

Characterization of the Head Stabilization Response to a Lateral Perturbation During Walking in Older Adults

A main contributor of fractures in older adults is from a lateral fall. The decline in sensory systems results in difficulty maintaining balance stability. Head stabilization contributes to postural control by serving as a stable platform for the sensory systems. The purpose of this study was to characterize the head stabilization response to a lateral perturbation while walking. A total of 16 healthy older adults, aged 66-81 years, walked across a foam pathway 6 times. One piece of the foam pathway covered a movable platform that translated to the left when the subject stepped on the foam. Three trials were randomized in which the platform shifted. Angular rate sensors placed on the center of mass of the head and trunk collected head and trunk movement in all three planes of motion. The roll plane was analyzed to examine motion in the plane of the perturbation. Subjects stepped onto the platform with the right foot. Recovery step time and distance were recorded. The first trial was analyzed to capture the novelty of the perturbation. Results indicate a significant difference in footfall distance t=0.004, p<0.05, as well as the speed of foot recovery t=0.001, p<0.05, between natural and perturbed walking. Results indicate that the head t=0.005, p<0.05, and trunk t=0.0001, p<0.05, velocities increase during perturbed compared to natural walking. Older adults place their recovery foot down faster when perturbed to re-establish their base of support. Head and trunk segments are less stable and move with greater velocities to reestablish stability when perturbed

Functional Mobility Performance and Balance Confidence in Older Adults after Sensorimotor Adaptation Training

Research indicates a main contributor of injury in older adults is from falling. The decline in sensory systems limits information needed to successfully maneuver through the environment. The objective of this study was to determine if prolonged exposure to the realignment of perceptual-motor systems increases adaptability of balance, and if balance confidence improves after training. A total of 16 older adults between ages 65-85 were randomized to a control group (walking on a treadmill while viewing a static visual scene) and an experimental group (walking on a treadmill while viewing a rotating visual scene). Prior to visual exposure, participants completed six trials of walking through a soft foamed obstacle course. Participants came in twice a week for 4 weeks to complete training of walking on a treadmill and viewing the visual scene for 20 minutes each session. Participants completed the obstacle course after training and four weeks later. Average time, penalty, and Activity Balance Confidence Scale scores were computed for both groups across testing times. The older adults who trained, significantly improved their time through the obstacle course F (2, 28) = 9.41, p < 0.05, as well as reduced their penalty scores F (2, 28) = 21.03, p < 0.05, compared to those who did not train. There was no difference in balance confidence scores between groups across testing times F (2, 28) = 0.503, p > 0.05. Although the training group improved mobility through the obstacle course, there were no differences between the groups in balance confidence