Decisional role of the dorsolateral prefrontal cortex in ocular motor behaviour

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.




Fig. 6 Cortical areas involved in saccades. After receiving visual information in the occipital lobe and after visuospatial integration in the PPC, a saccade may be either triggered reflexively, mainly by the PEF, or triggered intentionally by the FEF, an area which also appears to be involved in active visual fixation. If a reflexive saccade must be inhibited, the DLPFC appears to play a crucial role (1). This area is also involved in short-term spatial memory (2) and prediction (3) when anticipatory saccades must be performed. With these three different actions, the DLPFC could play an important role in the decisional processes controlling ocular motor behaviour. The SEF could be involved in motor programmes including several successive saccades, or saccades combined with other body movements, whereas the CEF appears to activate all the areas controlling intentional saccades via a motivation process. ACC = anterior cingulate cortex; CEF = cingulate eye field; cs = central sulcus; DLPFC = dorsolateral prefrontal cortex; FEF = frontal eye field; ips = intraparietal sulcus; ls = lateral sulcus; pcs = precentral sulcus; PEF = parietal eye field; PPC = posterior parietal cortex; RF = brainstem reticular formation; SC = superior colliculus; SEF = supplementary eye field; 1, 2, 3 = the main actions of the DLPFC; + = saccade triggering; – = saccade inhibition.

C. Pierrot-Deseilligny , R. M. Müri , C. J. Ploner , B. Gaymard , S. Demeret , and S. Rivaud-Pechoux .
Decisional role of the dorsolateral prefrontal cortex in ocular motor behaviour.
Brain Advance Access published on June 1, 2003, DOI 10.1093/brain/awg148.
Brain 126: 1460-1473.

http://brain.oxfordjournals.org/cgi/content/full/126/6/1460