Project: When attention meets perception: Non invasive neurostimulation technologies to boost visual perception in intact subjects and cerebrally damaged patients
Cerebral functions emerge from the activity of local and widely distributed cerebral networks. Their ability
to uptake and treat information is dependent on their patterns of anatomical and functional connectivity and the
temporal dynamics characterizing the encoding and flow of electrical signals between their nodes. The sensibility
range of such complex systems, which depends on its architecture and organization, appears to be well fixed and
defines our individual perceptual capabilities. Cerebral networks are however provided with a level of inherent
flexibility, which is underlined by rapid processes of plastic reorganization. Such plastic processes allows us to
continuously adapt to novel cognitive demands posed by specific operations within the environment. By doing so
they accommodate an essential ability for human survival, which is the acquisition, learning and amelioration in the
performance of tasks, such as those involving sensory discrimination. Furthermore, when those same networks are
exposed to focal areas of damage, those very same plastic properties can also provide the basis for clinical
recovery. In support of the importance of such phenomena, studies have massively shown the correlation between
ameliorations in human performance and dramatic molecular, cellular and synaptic plasticity effects occurring
within specific cerebral regions. Nonetheless, in the brain systems underlying vision, audition or touch, for
example, the achievement performance ameliorations can often be supported by rapid plastic mechanisms
embedded within the functionality of the network at play and mediated through its interactions with sets of
additional circuitry. In support of this idea, prior animal and human studies have provided strong evidence on the
relationships between spatial attention processing and visual detection/discrimination performance. Those reports
have emphasized the notion that both exogenous and endogenous visual sensory cues, covertly orienting attention
towards specific regions of the space, have the ability to flexibly modulate the gain of striate visual neurons, and by
doing so, induce ameliorations in our ability to discriminate a target displayed shortly thereafter. Unfortunately, the
effects of cuing is temporally limited to trial duration and its ability to effectively use them to ameliorate the visual
abilities of cerebrally damaged patients with low visual capabilities remains controversial. Conveniently, the
cerebral network involved in such attentional orienting processes its being actively investigated, revealing the
implication of a large-scale brain circuit, involving several posterior parietal, frontal and temporal regions. However,
the anatomical and functional interactions between those systems and the occipital areas involved in low level
visual processing; and the ability to efficiently manipulate the former to boost visual discrimination performance in
intact subjects or in cortically damaged patients affected by visual problems remains poorly explored.
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