Inclination of eye-tracking tracing. (A localising parameter in electro-oculography)

A new diagnostic parameter in electro-oculography, viz. 'Inclination of eye-tracking tracing' is presented. Electro-oculographically the pendular eye-tracking tracing was recorded before and after calorization, using the technique of serial thermal vestibulometry. In some cases of brain-stem lesion, the tracing inclined in the direction of the slow component of the calorically-induced nystagmus; but this phenomenon was not noted in cases with peripheral lesions, nor in pure frontal, occipital, parietal of cerebellar lesions. A neuro-anatomical model is postulated in explanation of this phenomenon. It appears that the basic lesion responsible for this phenomenon is a small one partially involving the slow-discharging neuronal units in the lower reticular core and in the adjacent suprasegmental inhibitory cortico-reticular tracts, thus bringing about a state of relative hyperactivity (release phenomenon) of the remaining surviving neurones which belong to the slow-discharging neuronal units. The latter has been referred to here as the 'Inclination Neuronal Mechanism' and this phenomenon appears to be the converse of "Central vestibular recruitment', the former being caused by a lesion in the 'slow-discharging units', the latter by a lesion in the 'quick-discharging units' ('nystagmogenic area'), the two units belonging to the same reticular system but having opposite functions.