Visual perception

Neuroimaging studies have suggested that hMT+ encodes global motion interpretation, but this contradicts the notion that BOLD activity mainly reflects neuronal input.

While measuring fMRI responses at 7 Tesla, we used an ambiguous moving stimulus, yielding the perception of two incoherently moving surfaces - component motion - or only one coherently moving surface - pattern motion , to induce perceptual fluctuations and identify perceptual organization size‐matched domains in hMT+.

The response amplitude of pattern motion domains did not change with grating direction (consistently with their non‐selective input), in contrast to what happened for the component motion domains (consistently with their selective input). However, when we analyzed relative ratio measures they mirrored perceptual interpretation.

These findings are consistent with the notion that patterns of BOLD responses reflect both sensory input and perceptual read‐out.

Sousa et al. (2021). DOI: 10.1002/hbm.25339.

Two mechanisms may help explain the hysteresis phenomenon in human visual experience: adaptation and persistence.

We found evidence for a continuous competition between these perceptual history mechanisms, together with a stronger involvement of the anterior insula when persistence dominated.

Our results support the hypothesis of differential brain network recruitment for the two mechanisms and provide further insight into the underlying causes of hysteresis in multistable perception.

Sayal et al. (2020). DOI: 10.1016/j.neuroimage.2020.117153.

Perceptual long-range integration of bistable motion can be tracked by changes in interhemispheric functional connectivity between left/right hMT+.

hMT+ interhemispheric functional connectivity reflects perceptual decision, suggesting its pivotal role on long-range disambiguation of bistable physically constant surface motion.

Sousa et al. (2019). DOI: 10.1038/s41598-018-37822-x.

The strength of the measured visual adaptation effect depends on whether subjects integrated (coherent percept) or segregated (incoherent percept) surface motion signals.

Adaptation can contribute to regulate percept duration during visual bistability, with distinct weights, depending on the type of percept, in an asymmetric manner.

Sousa et al. (2018). DOI: 10.1016/j.neuroimage.2018.06.075.

Higher signal changes were found in hMT+ in response to spatially segregated component (incoherent) percepts than to pattern (coherent) percepts. This did not occur in early visual cortex, unlike apparent motion, which does not entail surface segmentation.

Long‐range interhemispheric binding of ambiguous motion representations mainly reflect bottom–up processes from hMT+ during perceptual state maintenance. In contrast, state transitions maybe influenced by high‐level regions such as the SPL.

Duarte et al. (2017). DOI: 10.1002/hbm.23701.

A critical test to the binding-by-synchrony hypothesis by evaluating long-range connectivity using EEG during a motion integration visual task that entails binding across hemispheres.

Large-scale perceptual binding is not associated with long-range interhemispheric gamma synchrony. However, distinct perceptual interpretations were found to correlate with changes in beta power.

Costa et al. (2017). DOI: 10.1162/jocn_a_01158.

Working memory load and perceptual reversals of the Necker cube compete for attentional resources.

Posterior Superior Parietal Lobule is directly linked with perceptual reversals. Fronto-parietal networks modulate perceptual decisions as a linear function of load.

aPFC and DLPFC respond to load vs. reversal rate in a mirror-like manner.

Intaitè et al. (2016). DOI: 10.1016/j.brainres.2016.08.044.