Sensorimotor adaptation and learning in the control of human standing balance in cerebellar ataxia patients

Recent studies have provided insights into the capabilities and mechanisms of
sensorimotor adaptation and learning in human standing balance. These include
establishing the underlying mechanisms for the nervous system to recalibrate to
novel sensory feedback, adjust control when sensory-motor relationships change,
and learn to maintain standing under conditions which are initially
destabilizing. However, it remains largely unclear which neural structures are
responsible for these adaptive learning processes. A candidate brain region is
the cerebellum, given its roles in multisensory integration and sensorimotor
prediction, though several questions regarding its involvement in adaptive
learning remain unanswered. What types of adaptive processes in standing
balance control does the cerebellum contribute to? If cerebellar function is
compromised, can other parts of the nervous system accommodate for the
dysfunction and facilitate sensorimotor learning? And if possible, under what
sensorimotor conditions can this be achieved? With the research proposed here,
we seek to understand whether compromised cerebellar function impairs
sensorimotor adaptation and learning in human standing balance. Furthermore, we
seek to determine what sensory feedback conditions are optimal for cerebellar
patients to adapt and learn new balance tasks.

The primary objective of this study is to establish whether cerebellar patient
populations can adapt and learn to maintain standing balance when sensory-motor
relationships of balance are modified. By comparing patient behavior with
age-matched control participants, we will determine whether disrupted
cerebellar function impedes the sensorimotor learning processes involved in
standing balance.

All experiments will involve healthy controls and cerebellar patients
performing standing balance experiments on a robotic balance simulator. This
simulator is used to control, replicate, and modify the mechanics and
sensory-motor relationships for ongoing standing.

Healthy participants will visit the Erasmus MC at least once (up to 2 times)
and an experiment will last for a maximum of 2 hours. The total time spent
testing a subject will be limited to 4 hours regardless of experimental
protocol. In this study, the safety measures are applied as described in recent
human balance and sensory stimulation reviews. There are no serious risks
associated with this study. The discomfort and risks associated with the
experiments described in this proposal are minor but vary according to the
methods used for each experiment. The risks/discomfort for the various
techniques used are provided below.

Robotic balance simulator
Standing in the robotic balance simulator may cause vertigo and nausea for
participants who are particularly subject to those complaints. When a subject
indicates vertigo and/or nausea during any experiment and indicates that they
wish to end the experiment, this request will be granted immediately.