Medial vs Lateral Frontal Lobe Lesions and Differential Impairment of Central-Gaze Fixation Maintenance in Man

Abstract

The ability to maintain central-gaze fixation was studied in 35 patients with unilateral frontal lobe lesions. The stability of central-gaze fixation was tested in 2 oculomotor tasks requiring the suppression of reflexive saccades triggered by the sudden appearance of novel, peripheral visual stimuli. In the first task ('Instructed'), maintenance of gaze fixation was based on verbal instruction, whereas, in the second task ('Non-instructed'), it was based upon a foveating mechanism maintained by sensory stimulation during the performance of a categorization task. Patients with frontal lobe lesions were classified into 3 groups: a ventrolateral (n = 18), a dorsolateral (n = 10) and a medial (n = 7) group. The control group consisted of 20 healthy subjects. In the Non-instructed task, no group differences were found in the rate of reflexive saccades. Thus, lesions of the frontal lobe did not affect reactivity to extraneous stimuli per se. The only exception to this rule was the group of patients with ventrolateral lesions in the left frontal lobe, in which a higher number of reflexive saccades directed to the contralateral hemifield was observed. In the Instructed task, 2 different patterns of deficit in suppression of reflexive saccades were found. First, a bidirectional deficit was noted in the ventrolateral group, which might be attributed to an impairment in either maintaining a selected program of behaviour 'on-line' or suppressing inappropriate alternatives interfering with that program. Second, a unidirectional deficit in voluntary suppression of reflexive saccades triggered from within the contralateral hemifield was observed in the medial group. It is suggested that this type of deficit may reflect malfunctioning of the supplementary motor area--anterior cingulate system involved in the suppression of externally triggered interfering programs. Finally, no significant impairment was found in the dorsolateral group.

Oculomotor Areas of the Primate Frontal Lobes: A Transneuronal Transfer of Rabies Virus and [14C]-2-Deoxyglucose Functional Imaging Study

“…Moreover, areas 24 and 32 are activated during saccades toward or away from visual targets and toward memorized targets (Anderson et al, 1994;Doricchi et al, 1997). In agreement with our data, the anterior cingulate (including areas 32 and 24) is activated by fixation of visual (Anderson et al, 1994) or imaginary (Petit et al, 1995) targets, and its lesion impairs suppression of reflexive saccades in humans (Paus, 1991).…”

Errors recruit both cognitive and emotional monitoring systems: Simultaneous intracranial recordings in the dorsal anterior cingulate gyrus and amygdala combined with fMRI

“…Alternatively, the dorsal ACC could be involved in the suppression of externally triggered interfering programs (i.e. involved in overriding response; see Paus et al, 1991). Also plausible here, is the possibility that the ACC activity we recorded in this patient (SG) during the go/nogo task actually reflected response selection, rather than error monitoring per se (see Liu, Banich, Jacobson, & Tanabe, 2006).…”

The role of prefrontal cortex in working-memory capacity, executive attention, and general fluid intelligence: An individual-differences perspective

“…Often, though, patients with frontal damage do perform more poorly than healthy control subjects on these brief recall tasks (Baldo & Shimamura, 1998;Butters et al, 1994;Janowsky, Shimamura, Kritchevsky, & Squire, 1989;Laiacona et al, 1989;Owen, Downes, Sahakian, Polkey, & Robbins, 1990;Paus et al, 1991;Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998;Tucha, Smely, & Lange, 1999).…”