Eye Movement and Neuronal Response in the Region of the Interstitial Nucleus of Cajal during Sinusoidal Vertical Linear Acceleration in Alert Cats

Abstract

We examined neuronal behavior and eye movement response to sinusoidal vertical linear acceleration in the INC region. In light, robust eye movement response with near compensatory phase was consistently evoked over wide frequencies. Without visual inputs, the linear vestibulo-occular reflex (LVOR) with advanced phase was inconsistently evoked. Optokinetic stimulation alone produced more lag of response phase as stimulus frequency increased, suggesting that the otolith inputs contributed to the eye movement response with near compensatory phase in light. The activity of all burst-tonic (BT) neurons tested which showed close correlation with spontaneous vertical eye movement was modulated during linear motion in light and during optokinetic stimulation in association with eye movement responses. Without visual inputs, similar linear motion produced no response in a majority of BT cells even when the LVOR was evoked. These results suggest that BT cells are involved in some aspect of the generation of a functionally important vertical eye position signal using the otolith and visual inputs. Many cells in the INC region that did not belong to BT cells responded to linear acceleration without visual inputs and optokinetic stimulation even when eye movement response was not evoked, indicating that these cells received the otolith and visual inputs.

Key Words:

• linear vestibulo-ocular reflex
• optokinetic eye movement
• otolith-visual interaction
• interstitial nucleus of Cajal
• burst-tonic neuron
• alert cat