ATTENTION&CONSCIOUS · Attention and consciousness in the brain

Attention and consciousness in the brain

The main objective of this project was to better understand the relation between different forms of attention and their impact on conscious perception. It is well established that a great amount of information reaching our senses can be processed at several levels of depth, even if it cannot be consciously reported (see e. g., Kouider & Dehaene, 2007). A fundamental question in the study of conscious perception involves the neurocognitive mechanisms determining or modulating the selection for consciousness. Attention has often been considered as one of the important mechanisms gating access to conscious perception (Chun & Marois, 2002; O'Regan & No?, 2001; Posner, 1994). However, the hypothesis of a systematic relationship between spatial attention and conscious perception has been challenged by recent studies demonstrating that not all forms of attention are necessary for conscious perception (Koch & Tsuchiya, 2007; see also Koivisto, Kainulainen, & Revonsuo, 2009). Using different and complementary techniques and searching converging evidence, we first aimed at disentangling and dissecting out the neural networks underlying endogenous and exogenous orienting. Then, we studied the relationship between such types of attention, their influence on perceptual consciousness, and whether the integrity of the attentional network involved in spatial orienting is putative and necessary for conscious perception. Our main results can be summarised as follows: 1) Endogenous and exogenous attention are implemented in differentiated but partially overleaping brain circuits, including key nodes of dorsal and ventral parietal regions (Bourgeois, Chica, Migliaccio, Thiebaut de Schotten, & Bartolomeo, under review; Bourgeois, Chica, Valero-Cabre, & Bartolomeo, in preparation; Chica, Bartolomeo, & Valero-Cabr?, 2011). 2) Some forms of attention such as exogenous spatial attention (Chica, Botta, Lupi??ez, & Bartolomeo, under review; Chica, Lasaponara, et al., 2011; Chica, Lasaponara, Lupi??ez, Doricchi, & Bartolomeo, 2010) and phasic alertness (Kusnir, Chica, Mitsumasu, & Bartolomeo, 2011) interact with subsequent conscious perception, and are important antecedents of our conscious experience. Other forms of attention, such as endogenous spatial attention, can instead be dissociated from conscious reports (Chica, Botta, et al., under review; Wyart & Tallon-Baudry, 2008). Interactions within fronto-parietal attentional networks underlie the interplay between exogenous attention and conscious perception (Chica, Paz-Alonso, Valero-Cabr?, & Bartolomeo, under review), suggesting that these fronto-parietal interactions are not only relevant for conscious perception as proposed by recent models (Dehaene, Changeux, Naccache, Sackur, & Sergent, 2006; Dehaene & Naccache, 2001; Lamme, 2006); they also play a crucial role during attentional orienting facilitating access to consciousness for attended targets. 3) TMS over key nodes of this attentional networks (in particular the left FEF) demonstrated their causal role on conscious perception, biasing attentional orienting and subsequent conscious reports (Chica, Valero-Cabr?, Paz-Alonso, & Bartolomeo, in preparation). Briefs excitatory TMS pulses have been successful in improving conscious perception in healthy participants, especially when attention is simultaneously engaged by using visual attentional cues (Chanes, Chica, Bartolomeo, & Valero-Cabre, under review). Three main conclusions can be extracted from our project: 1) Endogenous and exogenous attention consist of two independent attentional systems implemented in partially different brain regions; 2) Exogenous spatial attention influences conscious perception, and these interactions are tightly associated to the activity of dorsal and ventral fronto-parietal networks traditionally involved in attentional orienting; 3) Non-invasive neuro-stimulation techniques constitute a useful tool to investigate the causal role of attentional nodes in attention an

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