Tsubomi, H., Ikeda, T., Hanakawa, T., Hirose, N., Fukuyama, H., & Osaka, N.


Dissociable neural activations of conscious visibility and attention


Journal of Cognitive Neuroscience





Recent neuroimaging evidence indicates that visual consciousness of

objects is reflected by the activation in the lateral occipital cortex

as well as in the frontal and parietal cortex. However, most previous

studies used behavioral paradigms in which attention raised or enhanced

visual consciousness (visibility or recognition performance). This

co-occurrence made it difficult to reveal whether an observed cortical

activation is related to visual consciousness or attention. The present

fMRI study investigated the dissociability of neural activations

underlying these two cognitive phenomena. Toward this aim, we used a

visual backward masking paradigm in which directing attention could

either enhance or reduce the object visibility. The participantsʼ task

was to report the level of subjective visibility for a briefly presented

target object. The target was presented in the center with four

flankers, which was followed by the same number of masks. Behavioral

results showed that attention to the flankers enhanced the target

visibility, whereas attention to the masks attenuated it. The fMRI

results showed that the occipito-temporal sulcus increased activation in

the attend flankers condition compared with the attend masks condition,

and occipito-temporal sulcus activation levels positively correlated

with the target visibility in both attentional conditions. On the other

hand, the inferior frontal gyrus and the intraparietal sulcus increased

activation in both the attend flankers and attend masks compared with an

attend neither condition, and these activation levels were independent

of target visibility. Taken together, present results showed a clear

dissociation in neural activities between conscious visibility and


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