These differences were not due to variability of responses in the two areas; similar Fano factor values were observed in the two areas and similar modulation by task epochs and errors. Visual attention can be oriented to stimuli based either on their physical distinctiveness (bottom-up selection), based on salience or their behavioral relevance (top-down selection) based on prior information, expectations and goals. Selective neural
representation of visual stimuli based on their bottom-up saliency, in the form of enhanced responses to stimuli that pop out and reduction of responses to background elements, is observed among multiple visual cortical areas including early stages of cortical hierarchy such as V1 and the later stages such as LIP and FEF (Knierim & van Essen, 1992; Schall & Hanes, 1993; Gottlieb et al., 1998). In order to identify the most salient Stem Cell Compound Library high throughput stimulus in the visual field and guide bottom-up attention efficiently, it is critical to be able to integrate all types of information in the visual field as fast as possible into a map of global saliency (Koch & Ullman, 1985;
Niebur & Koch, 1996). Combining both bottom-up and top-down factors, a global priority map in the brain is thought to play a role in integrating separate streams of visual information and orienting attention (Serences & Yantis, 2006; Bisley & Goldberg, 2010). So far, several different brain areas such selleck screening library as LIP and 7a of the PPC (Gottlieb et al., 1998; Constantinidis & Steinmetz, 2001), FEF and areas 8 and 46 of the prefrontal cortex (Schall & Hanes, 1993; Katsuki & Constantinidis, 2012a), and the superior colliculus (McPeek & Keller, 2002) are thought
to represent saliency/priority maps. Anatomically, these areas are interconnected (Segraves & Goldberg, 1987; Cavada & Goldman-Rakic, 1989b; Felleman & Van Essen, 1991; Schall et al., 1995; Stanton et al., 1995; Pare & Wurtz, 1997) and receive projections from many visual cortical areas (Cavada & Goldman-Rakic, 1989a; Morel & Bullier, 1990; Schall et al., 1995; Masitinib (AB1010) Lock et al., 2003). Comparisons of neuronal responses between areas indicate that a pop-out visual stimulus in the receptive field is discriminated from the background stimuli in the neuronal activity of the frontal areas (FEF, area 46) and posterior parietal areas (LIP) at similar timing (Thompson et al., 1996; Thomas & Pare, 2007; Katsuki & Constantinidis, 2012a). Thus, representation of visual salience in these areas could be processed in parallel and may contribute to attention deployment and following behavioral responses differently. A number of studies have suggested that activity of neurons in PFC, PPC and the superior colliculus influences behavioral choice, through accumulation of sensory evidence over time (Burman & Bruce, 1997; Schall & Thompson, 1999; Carello & Krauzlis, 2004; Hanks et al., 2006; Purcell et al., 2010).