Leaky neural integration observed in square-wave jerks.
OBJECTIVE
To clarify the neuronal mechanism for the square-wave jerks (SWJs).


METHODS
A 66-year-old man presented with oscillatory eye movements. He showed horizontal nystagmus in rightward gaze and SWJs during fixation at straight ahead. We recorded his eye movements with search coil methods and quantitatively analyzed them.


RESULTS
Visually guided rightward saccades were followed by exponential drifts with average time constants of 0.3-1.0 second, indicating a leaky rightward velocity-to-position integrator. Amplitude of SWJs ranged from 0.5 to 2.5 degrees and average intersaccadic interval was 0.2 seconds. In addition, exponential drifts similar to those observed after visually guided saccades were observed in the SWJs. Rightward fast eye movements of SWJs were followed by exponential drifts lasting for 0.2 seconds with average time constant (+/-SD) of 0.7+/-0.3 seconds.


CONCLUSIONS
Position signals after visually guided saccades and SWJs were outputs of the identical velocity-to-position integrator. SWJs are generated by the neural circuits involving a pulse generator and a velocity-to-position integrator.
Suzuki
Yasuo
Y
Department of Ophthalmology, Sapporo Medical University, School of Medicine, Sapporo, Japan.
Kase
Manabu
M
Hashimoto
Masato
M
Ohtsuka
Kenji
K
D000368:Aged; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000209:etiology*; D009422:Nervous System Diseases / Q000150:complications*; D009801:Oculomotor Muscles / Q000294:innervation*; D012438:Saccades