A re-examination of the time constant of the oculomotor neural integrator in human

Abstract

We studied the horizontal oculomotor neural integrator in healthy human subjects during gaze holding in darkness. We found large variability among subjects with respect to the estimated time constants and the integrator's null position. We also found that individual subjects could demonstrate significantly nonlinear drift velocities as a function of eye position. Nevertheless, a consistent trend did not emerge. Consequently, cross subject averaging eliminates idiosyncratic nonlinear patterns and the average can be approximated by a linear function inside the range that was tested. Abstract-We studied the horizontal oculomotor neural integrator in healthy human subjects during gaze holding in darkness. We found large variability among subjects with respect to the estimated time constants and the integrator's null position. We also found that individual subjects could demonstrate significantly nonlinear drift velocities as a function of eye position. Nevertheless, a consistent trend did not emerge. Consequently, cross subject averaging eliminates idiosyncratic nonlinear patterns and the average can be approximated by a linear function inside the range that was tested.

Role of neural integrators in oculomotor systems: a systematic narrative literature review

“…When fixating >+20° rightwards, the drift velocity began to decrease, contradicting the linear function that had been hypothesized (Khojasteh et al. ). This is possibly due to the rarity in looking at eccentric positions without moving our head.…”

“…Although Khojasteh et al. () assessed vertical gaze holding, these results were not reported. The ocular drift in healthy subjects has been found to have a component of gravity dependence in complete darkness (Marti et al.…”

“…Recently, NI performance was reassessed in normal human subjects; average was 24.8 seconds for horizontal gaze holding (Khojasteh et al. ). Although the time constants are similar, the methodologies were dissimilar.…”

“…Furthermore, healthy subjects with no known pathologies exhibited end‐point nystagmus (EPN) when viewing a target over 35° eccentricity (Khojasteh et al. ; Bertolini et al. ).…”

“…; Karatas ; Baier & Dieterich ; Kheradmand & Zee ; Khojasteh et al. ; Nakamagoe et al. ; Rowe et al.…”