Stimulating the inferior fronto-occipital fasciculus elicits complex visual hallucinations

Andelman-Gur, Michal M.; Gazit, Tomer; Strauss, Ido; Fried, Itzhak; Fahoum, Firas

doi:10.1016/j.brs.2020.09.003

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…Parts of the IFOF are associated with visual processing ( 26 ) by visual conceptualisation ( 27 ) and visual hallucinations ( 28 , 29 ). Our results suggest that the WM alterations in these regions might indicate atypical visual processing in patients with VSS.…”

Section: Discussionmentioning

confidence: 99%

Widespread White Matter Alterations in Patients With Visual Snow Syndrome

et al. 2021

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Background: Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant binocular flickering or pixilation of the whole visual field. The underlying neurophysiological and structural alterations remain elusive.Methods: In this study, we included patients (final n = 14, five dropouts; five females, mean age: 32 years) with visual snow syndrome (VSS) and age- and sex-matched controls (final n = 20, 6 dropouts, 13 females, mean age: 28.2 years). We applied diffusion tensor imaging to examine possible white matter (WM) alterations in patients with VSS.Results: The patient group demonstrated higher (p-corrected < 0.05, adjusted for age and sex) fractional anisotropy (FA) and lower mean diffusivity (MD) and radial diffusivity (RD) compared to controls. These changes were seen in the prefrontal WM (including the inferior fronto-occipital fascicle), temporal and occipital WM, superior and middle longitudinal fascicle, and sagittal stratum. When additionally corrected for migraine or tinnitus—dominant comorbidities in VSS—similar group differences were seen for FA and RD, but less pronounced.Conclusions: Our results indicate that patients with VSS present WM alterations in parts of the visual cortex and outside the visual cortex. As parts of the inferior fronto-occipital fascicle and sagittal stratum are associated with visual processing and visual conceptualisation, our results suggest that the WM alterations in these regions may indicate atypical visual processing in patients with VSS. Yet, the frequent presence of migraine and other comorbidities such as tinnitus in VSS makes it difficult to attribute WM disruptions solely to VSS.

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Section: Discussionmentioning

confidence: 99%

Widespread White Matter Alterations in Patients With Visual Snow Syndrome

et al. 2021

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“…In a recent study, a review of numerous stimulation sites in pre-frontal cortex failed to reveal consistent perceptual effects (Raccah et al, 2021). Although other studies have argued for the occurrence in a minority of patients of complex visual hallucinations (Blanke et al, 2000), these may be associated with spread of activation to fiber pathways (Andelman-Gur et al, 2020).…”

Section: Brain Lesions and Stimulation Support The Localist Viewmentioning

confidence: 98%

The Role of the Prefrontal Cortex in Conscious Perception: The Localist Perspective

Malach

2022

Journal of Consciousness Studies

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In recent years the role of the prefrontal cortex (PFC) in conscious perception has acquired great interest since it became a pivotal issue distinguishing among prevailing neuronal theories of human consciousness. One can identify three major, and conflicting, views of this role. The globalist view proposes that the PFC is a major hub in a global workspace whose activation is a critical component for any conscious experience. The higher-order thought theory argues that the PFC has a more specialized role underlying higher-order reflection or evaluation, proposed to be an essential element of consciousness. By contrast, the localist view argues that conscious content is linked to localized activations in content-specific cortical areas with no privileged role assigned to the prefrontal cortex in conscious experience in general. According to the localist view, just as posterior cortical areas underlie the conscious experience of visual perceptions, so does the prefrontal cortex underlie the conscious experience of specific categories of conscious contents such as reporting, thinking, speech, and introspection. Here I will review experimental evidence derived from human imaging and recordings, cortical lesions, and direct electrical stimulation in awake patients. Findings from these

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“…A recent investigation using invasive brain stimulation attempted to uncover the function of these networks by visualizing the white matter that composes the inferior fronto-occipital fasciculus (IFOF), which is a white matter tract within the orbito-frontal region associated with semantic language processing. Stimulating the electrodes implanted near this network elicited complex visual hallucinations in two patients, which suggests that stimulation location and the pathways related to language processing play a big role in the mapping of cognitive functions ( Andelman-Gur et al, 2020 ). Despite these ongoing stimulation studies uncovering the mechanisms and regions involved in speech, evoking artificial speech-like perceptions with DCS poses several key challenges: the complexity of brain areas involved in speech cognition, the inhibition or decrease in neural activity during electrical stimulation on language areas, and the lack of knowledge regarding the mechanisms of stimulation.…”

Section: Challenges Of Inducing Artificial Speech Perception With Dir...mentioning

confidence: 99%

“…In the 1900s, Penfield and Rasmussen evoked visual perceptions of phosphenes when stimulating the occipital cortex ( Penfield and Rasmussen, 1950 ). DCS near the occipital cortex, specifically occipitotemporal and occipito-parietal areas, evoked visual perceptions such as patterns, spots, shapes, flashes of light, colors, and phosphenes in the external world ( Mégevand et al, 2014 ; Andelman-Gur et al, 2020 ). This is not to be confused with complex speech and déjà vu related perceptions, where stimulation evokes scenes or people inside the mind.…”

Section: Introductionmentioning

confidence: 99%

Evoking artificial speech perception through invasive brain stimulation for brain-computer interfaces: current challenges and future perspectives

Hong,

Ryun,

Chung

2024

Front. Neurosci.

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Encoding artificial perceptions through brain stimulation, especially that of higher cognitive functions such as speech perception, is one of the most formidable challenges in brain-computer interfaces (BCI). Brain stimulation has been used for functional mapping in clinical practices for the last 70 years to treat various disorders affecting the nervous system, including epilepsy, Parkinson’s disease, essential tremors, and dystonia. Recently, direct electrical stimulation has been used to evoke various forms of perception in humans, ranging from sensorimotor, auditory, and visual to speech cognition. Successfully evoking and fine-tuning artificial perceptions could revolutionize communication for individuals with speech disorders and significantly enhance the capabilities of brain-computer interface technologies. However, despite the extensive literature on encoding various perceptions and the rising popularity of speech BCIs, inducing artificial speech perception is still largely unexplored, and its potential has yet to be determined. In this paper, we examine the various stimulation techniques used to evoke complex percepts and the target brain areas for the input of speech-like information. Finally, we discuss strategies to address the challenges of speech encoding and discuss the prospects of these approaches.

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Stimulating the inferior fronto-occipital fasciculus elicits complex visual hallucinations

Cited by 7 publications

References 10 publications

Widespread White Matter Alterations in Patients With Visual Snow Syndrome

Widespread White Matter Alterations in Patients With Visual Snow Syndrome

The Role of the Prefrontal Cortex in Conscious Perception: The Localist Perspective

Evoking artificial speech perception through invasive brain stimulation for brain-computer interfaces: current challenges and future perspectives

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