Local feedback signals are not distorted by prior eye movements: evidence from visually evoked double saccades.
J Neurophysiol
; 78(1): 533-8, 1997 Jul.
Article
em En
| MEDLINE
| ID: mdl-9242302
ABSTRACT
Recent experiments have shown that the amplitude and direction of saccades evoked by microstimulation of the monkey superior colliculus depend systematically on the amplitude and direction of preceding visually guided saccades as well as on the postsaccade stimulation interval. The data are consistent with the hypothesis that an eye displacement integrator in the local feedback loop of the saccadic burst generator is gradually reset with a time constant of approximately 45 ms. If this is true, similar effects should occur during naturally evoked saccade sequences, causing systematic interval-dependent errors. To test this prediction in humans, saccades toward visual single- and double-step stimuli were elicited, and the properties of the second saccades were investigated as a function of the intersaccadic interval (ISI). In 15-20% of the saccadic responses, ISIs fell well below 100 ms. The errors of the second saccades were not systematically affected by the preceding primary saccade, irrespective of the ISI. Only a slight increase in the endpoint variability of second saccades was observed for the shortest ISIs. These results are at odds with the hypothesis that the putative eye displacement integrator has a reset time constant >10 ms. Instead, it is concluded that the signals involved in the internal feedback control of the saccadic burst generator reflect eye position and/or eye displacement accurately, irrespective of preceding eye movements.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estimulação Luminosa
/
Movimentos Sacádicos
/
Transdução de Sinais
Tipo de estudo:
Clinical_trials
/
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
J Neurophysiol
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Holanda