The correlation between interoception and equilibrium: exploring how interoceptive signals impact on postural balance in patients with spinal cord injury and in healthy subjects

Interoception allows monitoring inner states of the body through the inputs received from the organism. The interoceptive system is involved in several functions from lower to higher levels and recently it was demonstrated that interoceptive stimuli are involved also in the maintenance of balance in the vestibular system. Postural balance is fundamental in everyday life and healthy individuals requires multisensory integration of different signals, such as visual, vestibular and somatosensory, to properly maintain it. Patients with Spinal Cord Injury (SCI) usually display an impairment in balance and a reduction in sensitivity towards their internal states and interoceptive awareness. Anyway, the correlation between the interoceptive system and balance in healthy subjects and in SCI patients is poorly investigated. So in the current study, we aimed to investigate whether interoception can impact on postural balance, in order to improve the rehabilitation of SCI patients. In this part of the study we focused on the control group and 26 healthy subjects were recruited. The experimental session was composed of a neuropsychological assessment, followed bybalance tasks. To investigate balance we used Hunova – Movendo Technology and we proposed four conditions based on the type of balance (static and dynamic) and on visual inputs (eyes open and eyes closed). Lastly, participants underwent the Heartbeat Counting Task (HBCT) to evaluate interoceptive accuracy. We found that during dynamic balance lower distances between mediolateral trunk oscillation with eyes closed and with eyes open predicted better performance at the HBCT. The same effect was found also for the anteroposterior centre of pressure (COP) oscillation during static balance. It was found that during static balance, the higher was the difference between mediolateral trunk oscillation with eyes open and with eyes closed, the better was the performance at the HBCT. These results suggest an involvement of interoceptive abilities on balance.