Head stabilization shows multisensory dependence on spatiotemporal characteristics of visual and inertial passive stimulation

Sensorimotor coordination relies on fine calibration of the interaction among visual, vestibular, and somatosensory input. Our goal was to investigate how the spatiotemporal properties of passive inertial motion and visual input affect head stabilization. Healthy young adults (n=12) wore a head-mounted display during A/P sinusoidal horizontal translations of the whole body. Visual conditions (VIS) displayed forward (EO), sideways (SW), or backward (BW) visual motion relative to the head, plus an eyes-closed conditions (EC) which were combined with 4 inertial conditions to comprise 16 conditions in total. In SW either near or far DEPTH of field with 180° phase shift was displayed. Subjects were secured in a seat with head free to move. Frequency and amplitude of sinusoidal input included overlapping max acceleration (amax) or max velocity (vmax). Amplitude and phase of angular velocity was collected with a 3-axis gyro. A main effect of inertial condition on amplitude for all axes of head motion (p<.0000) and a shift (p<.0000) from phase lead to lag of head pitch with increasing freq (121°, 127°, 83°, −32°) were found. A main effect of VIS on head pitch (p<0.01) was due to the absence of vision (EC). An interaction effect between inertial and VIS conditions on head yaw occurred with SW (p<0.05). In SW, a significant interaction of depth of field and inertia on amplitude (p<0.001) and phase (p<0.05) of head yaw occurred, especially during high vmax conditions. Thus, visual flow can organize lateral cervical responses despite being discordant with inertial input.