Decisional role of the dorsolateral prefrontal cortex in ocular motor behaviour

Abstract

Three patients with a unilateral cortical lesion affecting the dorsolateral prefrontal cortex (DLPFC), i.e. Brodmann area 46, were tested using different paradigms of reflexive saccades (gap and overlap tasks), intentional saccades (antisaccades, memory-guided and predictive saccades) and smooth pursuit movements. Visually guided saccades with gap and overlap, latency of correct antisaccades and memory-guided saccades and the gain of smooth pursuit were normal, compared with controls. These results confirm our anatomical data showing that the adjacent frontal eye field (FEF) was unimpaired in these patients. The specific pattern of abnormalities after a unilateral DLPFC lesion, compared with that of the FEF lesions previously reported, consists mainly of: (i) a bilateral increase in the percentage of errors in the antisaccade task (misdirected reflexive saccades); (ii) a bilateral increase in the variable error in amplitude, without significant decrease in the gain, in the memory-guided saccade task; and (iii) a bilateral decrease in the percentage of anticipatory saccades in the predictive task. Taken together, these results suggest that the DLPFC plays a crucial role in the decisional processes, preparing saccades by inhibiting unwanted reflexive saccades (inhibition), maintaining memorized information for ongoing intentional saccades (short-term spatial memory) or facilitating anticipatory saccades (prediction), depending upon current external environmental and internal circumstances.

Prefrontal Cortex Deactivation in Macaques Alters Activity in the Superior Colliculus and Impairs Voluntary Control of Saccades

“…This hypothesis, however, fails to explain the long reaction time of saccades in these disorders. Alternatively, it has been proposed that response errors occur when a stopping signal is generated too late (Guitton et al, 1985;Pierrot-Deseilligny et al, 2003).…”

Reduced Attentional Engagement Contributes to Deficits in Prefrontal Inhibitory Control in Schizophrenia

“…Cognitive neuroscience provides a useful framework for understanding mechanisms that support automatic and voluntary attention (1) and how disturbances in these processes may contribute to problems in the executive control of behavior (2). The linkage between oculomotor and attentional brain systems (3,4) make eye movement paradigms particularly relevant for investigating mechanisms of attentional and inhibitory control deficits in schizophrenia (5).…”

Event-related power modulations of brain activity preceding visually guided saccades

“…They are generated in the brain stem, but there is extensive evidence from electrophysiological studies in monkeys (Bruce and Goldberg, 1985;Funahashi et al, 1989;Funahashi et al, 1990;Lynch et al, 1977;Schlag and Schlag-Rey, 1987) as well as from neuroimaging (Anderson et al, 1994;Fox et al, 1985;Law et al, 1997;Luna et al, 1998;Sweeney et al, 1996) and lesion studies in humans (Pierrot-Deseilligny et al, 2003a;Pierrot-Deseilligny et al, 1991b) that the cerebral cortex is involved in their control and preparation. Three main cortical areas are involved in the generation of saccades: the frontal eye field (FEF), located mostly at the intersection between the precentral sulcus and the superior frontal sulcus (Paus, 1996), the supplementary eye field (SEF), located on the medial surface of the superior frontal gyrus (Grosbras et al, 1999) and the parietal eye field (PEF), located in the intraparietal sulcus (Medendorp et al, 2003).…”