Figure 6.

Schematic representation of the sensory integration model: body sensors, neck sensors, and otoliths provide information about the body in-space, head-on-body, and head-in-space positions, respectively. As part of the central neural processing, the neck and body signals undergo coordinate transformation to indirectly encode head-in-space orientation. Overall, the optimal head-in-space estimate $\left({\tilde{H}}_S\right)$ is obtained by the relative weights of the otolith information (W_HD, blue pathway), coordinate-transformed information from the body and neck sensors (W_HI, green pathway), and the head prior information (W_HP, gray pathway). The head-in-space estimate $\left({\tilde{H}}_S\right)$ is then integrated with eye-in-head estimate $\left({\tilde{E}}_H\right)$ and line orientation on the retina to obtain an internal estimate of the upright orientation [i.e., subjective visual vertical (SVV)].