Preparatory Set Associated With Pro-Saccades and Anti-Saccades in Humans Investigated With Event-Related fMRI

Abstract

. Preparatory set associated with pro-saccades and anti-saccades in humans investigated with event-related fMRI. J Neurophysiol 89: 1016 -1023, 2003. First published October 30, 2002 10.1152/jn.00562.2002. Previous studies have shown that the BOLD functional MRI (fMRI) signal is increased in several cortical areas when subjects perform anti-saccades compared with pro-saccades. It remains unknown, however, whether this increase is due to an increased cortical motor signal for anti-saccades or due to differences in preparatory set between proand anti-saccade trials. To address this question, we measured eventrelated fMRI in a paradigm that allowed us to separate instructionrelated brain activity from saccade-related brain activity. In this paradigm, the instruction to either generate a pro-saccade or an antisaccade was conveyed by a switch in the color of the central fixation stimulus and preceded the presentation of a peripheral stimulus by either 6, 10, or 14 s. Cortical areas were functionally mapped using the general linear model comparing standard pro-and anti-saccade blocks with fixation blocks. When the trials were aligned on the onset of the instruction stimulus, bilateral frontal eye fields and right hemisphere dorsolateral prefrontal cortex showed an increased signal during the instruction period on anti-saccade trials as compared with pro-saccade trials. When the trials were aligned on the movement stimulus and the instruction period activity was subtracted, there were no differences between pro-and anti-saccades. This finding suggests that the increased cortical activation found in previous blocked designs originates predominately from differences in preparatory set and not from differences in the motor signal between pro-and anti-saccades.

Behavioral response inhibition and maturation of goal representation in prefrontal cortex after puberty

“…This is important because low levels of baseline activity were predictive of errors (Fig. S6), as found in other studies (40), and because baseline activity is likely related to response preparation, which has been identified as a critical parameter for the developmental improvement of inhibitory control (41,42). Baseline activity in our data may represent preparation for the task by virtue of representing the task rules ahead of the stimulus presentation.…”

Atypical involvement of frontostriatal systems during sensorimotor control in autism

“…The right dentate nucleus was also more active, suggesting increased activity in cerebello-thalamic circuitry as well as frontostriatal systems. Regions in this frontostriatal and cerebello-thalamic circuitry are typically involved in the execution of intentional behaviors based on internalized representations and cognitive plans rather than automatic responses to external sensory stimuli (Sweeney et al, 1996;DeSouza et al, 2003;Nitschke et al, 2004).…”

“…This could account for the greater dependence on the rostral frontostriatal pathways that are known to support saccades made on the basis of internally generated plans (Sweeney et al, 1996;DeSouza et al, 2003;Nitschke et al, 2004). However, when saccades are based on voluntary decisions, response latencies increase considerably relative to reflexive saccades, typically by more than 100 ms, in both typically developing individuals and individuals with autism (Munoz et al, 1998;Luna et al, 2002).…”

Assessment of age-related changes in inhibition and binding using eye movement monitoring.

“…DeSouza, Menon, and Everling (2003) found that activation within the dorsolateral prefrontal cortex was evident following the presentation of a cue stimulus that instructed viewers to either make a pro-or antisaccade in response to the target onset.…”