Right hemispheric dominance of visual phenomena evoked by intracerebral stimulation of the human visual cortex

Abstract

Electrical brain stimulation can provide important information about the functional organization of the human visual cortex. Here, we report the visual phenomena evoked by a large number (562) of intracerebral electrical stimulations performed at low-intensity with depth electrodes implanted in the occipito-parieto-temporal cortex of 22 epileptic patients. Focal electrical stimulation evoked primarily visual hallucinations with various complexities: simple (spot or blob), intermediary (geometric forms), or complex meaningful shapes (faces); visual illusions and impairments of visual recognition were more rarely observed. With the exception of the most posterior cortical sites, the probability of evoking a visual phenomenon was significantly higher in the right than the left hemisphere. Intermediary and complex hallucinations, illusions, and visual recognition impairments were almost exclusively evoked by stimulation in the right hemisphere. The probability of evoking a visual phenomenon decreased substantially from the occipital pole to the most anterior sites of the temporal lobe, and this decrease was more pronounced in the left hemisphere. The greater sensitivity of the right occipito-parieto-temporal regions to intracerebral electrical stimulation to evoke visual phenomena supports a predominant role of right hemispheric visual areas from perception to recognition of visual forms, regardless of visuospatial and attentional factors.

Lateral thinking – Interocular symmetry and asymmetry in neurovascular patterning, in health and disease

“…Demonstrating clear lateralisation of higher visual functions, right cortical electrical stimulations were more likely than left cortical stimulations to produce visual hallucinations in patients with epilepsy (Jonas et al, 2014).…”

“…This bias may explain the phenomenon of left field preference in some visual perception tasks (Verleger et al, 2009). Fascinatingly, right cortical electrical stimulations were more likely that left cortical stimulations to produce visual hallucinations in patients with epilepsy (Jonas et al, 2014). Further demonstrating the lateralisation present in many higher visual centres, the processing of symmetry perception appears to produce more activity in the right posterior regions (Bertamini and Makin, 2014), and colour discrimination is also processed in the right cerebral hemisphere (Danilova and Mollon, 2009).…”

Evaluating dipolar source localization feasibility from intracerebral SEEG recordings

“…The aims of the ICS during the SEEG investigations are (i) to identify the epileptogenic cortical structures whose stimulation elicits the usual seizures and (ii) to evaluate the residual cognitive function of these implanted structures (Jonas et al, 2012(Jonas et al, , 2014. In our source localization context, the ICS signal can be seen as a dipolar generator of electrical activity artificially placed at a known location and orientation inside the brain.…”

Awake perimetry testing for occipital epilepsy surgery

“…agree with the notion of Binder et al 2 that the outcome of epilepsy surgery in the occipital lobe has significantly increased with the introduction of modern MRI, video-EEG, and invasive monitoring over the years. The use of invasive monitoring by means of intracranial subdural [1][2][3]7,8,10,11,14,21 and depth 1,2,8,9,14,18,21 electrodes to delineate the epileptogenic zone is widespread, as is conducting extraoperative stimulation. 1,2,[9][10][11]21 In the same vein, functional MRI 13 and diffusion tensor imaging tractography 19 have been added to the preoperative diagnostic armamentarium to visualize eloquent cortex with existing visual field defects and optic white matter tracts, respectively ( Fig.…”

“…Complexity of elicited visual phenomena increases in a posteroanterior axis and can be categorized into simple (e.g., flashing lights), intermediate (simple geometrical shapes), and complex forms. 9,11 In particular, the left occipital cortex is known to have a substantially lower sensitivity for stimulation and lacks complex shapes compared with the visually dominant right occipital lobe during extraoperative stimulation using depth electrodes. 9 Moreover, 67% of the striate cortex is buried in the calcarine fissure with its branches and accessory sulci 15 and thus is inaccessible for stimulation.…”