The effect of the cognitive task in the walking of young adults when avoiding an obstacle and stepping on a target

Author(s)

Andréia Abud da Silva Costa

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2018-02-28

Examining board members

Renato de Moraes; Daniela Godoi Jacomassi; Fernando Henrique Magalhães; Paulo Roberto Pereira Santiago

• Advisor: Renato de Moraes

Abstract

During locomotion, we respond to environmental and task changes by adjusting step length and width. Different protocols of the stepping and avoidance tasks showed the involvement of cortical and subcortical pathways. The insertion of a concomitant cognitive task can affect in different ways these motor tasks, according to the pathway used. Thereby, we investigated the online adjustment using a double-step task and an obstacle avoidance task in young adults, and analyzed the effect of a cognitive task on these adjustments. Twenty young adults performed, during walking, a block of stepping task and a block of obstacle avoidance task. Both motor tasks were performed with and without a cognitive task, with the target/obstacle changing it position forward, backward, lateral or medial. The cognitive task was the digit-monitoring test, which consisted in memorizing how many times a previously stipulated target number appeared in a numerical sequence that the participants listened to while performing the motor task. We calculated the error rates in motor and cognitive tasks, latency, step speed, and foot orientation variability. In the obstacle avoidance task, we also calculated the percentage of choice adjustment and distance traveled by the foot. It was observed that the step speed decreased in the presence of the cognitive task. The stepping task presented higher rates of motor and cognitive errors compared to the obstacle avoidance task, as well as lower latencies in the mediolateral adjustments. The adjustments made in the frontal plane showed a greater foot orientation variability compared to the anteroposterior adjustments. Thus, the data suggest that the task of stepping on a target can be controlled by one of the two fast adjustment neural pathways, since the latency in the mediolateral adjustments was 150 ms, while the task of avoiding stepping on an obstacle presents latency of 200 ms and should be modulated by the cortical pathway used for slow adjustments. (AU)

• FAPESP's process: 16/02202-8 - Adaptive locomotion control in young adults during the tasks of alternate foot placement and step on target
• Grantee: Andréia Abud da Silva Costa
• Support Opportunities: Scholarships in Brazil - Master