Control of Predictive Error Correction During a Saccadic Double-Step Task

• Published in: Journal of neurophysiology Vol. 100; no. 5; pp. 2757 - 2770
• Main Authors: Sharika, K. M, Ramakrishnan, Arjun, Murthy, Aditya
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-11-2008
• Subjects: Attention - physiology; Feedback - physiology; Female; Humans; Male; Models, Biological; Photic Stimulation - methods; Predictive Value of Tests; Reaction Time - physiology; Saccades - physiology; Task Performance and Analysis; Time Factors
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.90238.2008

National Brain Research Centre, Nainwal More, Manesar, Haryana, India
Submitted 6 February 2008;
accepted in final form 16 September 2008
We explored the nature of control during error correction using a modified saccadic double-step task in which subjects cancelled the initial saccade to the first target and redirected gaze to a second target. Failure to inhibit was associated with a quick corrective saccade, suggesting that errors and corrections may be planned concurrently. However, because saccade programming constitutes a visual and a motor stage of preparation, the extent to which parallel processing occurs in anticipation of the error is not known. To estimate the time course of error correction, a triple-step condition was introduced that displaced the second target during the error. In these trials, corrective saccades directed at the location of the target prior to the third step suggest motor preparation of the corrective saccade in parallel with the error. To estimate the time course of motor preparation of the corrective saccade, further, we used an accumulator model (LATER) to fit the reaction times to the triple-step stimuli; the best-fit data revealed that the onset of correction could occur even before the start of the error. The estimated start of motor correction was also observed to be delayed as target step delay decreased, suggesting a form of interference between concurrent motor programs. Taken together we interpret these results to indicate that predictive error correction may occur concurrently while the oculomotor system is trying to inhibit an unwanted movement and suggest how inhibitory control and error correction may interact to enable goal-directed behaviors.
Address for reprint requests and other correspondence: A. Murthy, National Brain Research Centre, Near NSG Campus, Nainwal More, Manesar - 122 050, Haryana, India (E-mail: aditya{at}nbrc.ac.in )