Bistable



Attention, visual performance and conscious perception.
This behavioral study, conducted within the LBC, assessed whether endogenous visuospatial attention differentially affects visual discrimination sensitivity (an objective visual task performance) and visual awareness (the subjective feeling of perceiving) during the same discrimination task. For this, we used a unique discrimination task and signal detection theory models to simultaneously estimate both objective and subjective components of visual perception. Endogenous attention did or did not increase objective performance depending on the visual properties of the target stimuli, whereas it always increased conscious perception. Such results could be explained by an internal representation of one own’s attentional state, which can influence awareness independent of objective visual signals (Vernet et al., In press).

Brain network and bistable perception.
This study, conducted in the CNBS laboratory, addressed how the brain builds coherent 3D percepts. For this, we examined how it explores the different interpretations of bistable images, for which the percept spontaneously alternates in the consciousness of the observer. We combined for the first time a visual task, bifocal TMS (with two stimulation coils) and EEG to modulate the activity within attentional networks and therefore perception. We showed that parieto-frontal activities before a perceptual change of percept are not only an epiphenomenon: the emergence of a new 3D percept in consciousness is based on such a distributed mechanism (Vernet et al., 2015).


Brain oscillations and conscious perception. My research at the ICM aimed to prove the links between cortical rhythmic activity and perception. In several studies, we applied rhythmic TMS over areas of the visuo-spatial networks to modulate conscious perception and visual performance (Valero-Cabre et al., 2013; Chanes et al., 2015). The magnitude of the effects was correlated to structural connectivity measures, in line with the hypothesis that synchronizations in widespread network subtend conscious visual perception (Quentin et al., 2015a; Quentin et al., 2015b). A study to be published is demonstrating the possibility to entrain with rhythmic TMS high beta oscillations (~30 Hz) in the FEF during a visual task, and that this entrainment is functionally relevant: it correlates with increased visual detection.

Action and perception in 3D space. A literature review about the multiple roles of the Frontal Eye Field allowed us to develop the foundations about the role of attention networks and eye movements for conscious perception and navigation in 3D space (Vernet et al., 2014).

References

  • Chanes L, Quentin R, Vernet M, Valero-Cabré A (2015) Arrhythmic activity in the left frontal eye field facilitates conscious visual perception. Cortex. 71:240-7
  • Quentin R, Chanes L, Vernet M, Valero-Cabre A (2015 a) Fronto-Parietal Anatomical Connections Influence the Modulation of Conscious Visual Perception by High-Beta Frontal Oscillatory Activity. Cereb Cortex. 25(8):2095-101
  • Quentin R, Elkin Frankston S, Vernet M, Toba M, Bartolomeo P, Chanes L, Valero-Cabré A (2015b) Visual contrast sensitivity improvement by right frontal activity is mediated by contrast gain mechanisms and influenced by fronto-parietal white matter microstructure. Cerebral Cortex. Doi: 10.1093/cercor/bhv060
  • Valero-Cabre A, Quentin R, Vernet M, Chanes L (2013) Author response. Oscillation and synchrony entrainment: a new breadth for focal non-invasive neurostimulation in the cognitive neurosciences. J Neurosci 33:5 p following 11326.
  • Vernet M, Brem AK, Farzan F, Pascual-Leone A (2015) Synchronous and opposite roles of the parietal and prefrontal cortices in bistable perception: A double-coil TMS-EEG study. Cortex 64C:78-88
  • Vernet M, Japee S, Lokey S, Ahmed S, Ungerleider LG (In Press). Endogenous visuospatial attention increases visual awareness independent of visual discrimination sensitivity. Neuropsychologia.
  • Vernet M, Quentin R, Chanes L, Mitsumasu A, Valero-Cabre A (2014) Frontal eye field, where art thou? Anatomy, function, and non-invasive manipulation of frontal regions involved in eye movements and associated cognitive operations. Front Integr Neurosci 8:66.