Attentive and subconscious mechanisms of smooth pursuit

Abstract:

Ocular smooth pursuit is fragile and therefore a sensitive biomarker of many neurological problems. But numerous disorders produce similar pursuit deficits rendering pursuit diagnosis non-specific. We think this problem arises because pursuit is almost exclusively tested with a small spot - a stimulus that compels foveation which is a function of the saccadic system. We hypothesize that when a spot is pursued, it not only invokes pursuit, it spontaneously and simultaneously activates the saccadic system. As a result, this not only causes catch-up saccades but also introduces sub-saccadic signals into pursuit. Furthermore, while pursuit is characterized as attentive, we think attention is conferred to pursuit by the saccadic system, and that pursuit is otherwise driven by a subconscious mechanism. Alternatively, many characteristics of pursuit result only from it sharing circuitry with the saccadic system. We have evidence that non-spot pursuit stimuli, or alternative saccade targets, reduces catch-up saccades, and change attention allocation during pursuit. Experiments test: if attentive saccade signals modulate pursuit, if subconscious pursuit can be disentangled from saccades, and if attention selects spot and non-spot pursuit goals. Pursuit, of non-spot stimuli, may reveal different patterns of neural deficits that allow more specific diagnoses.