“…The deepest layer of prefrontal cortex, layer 6, is emerging as a key player in attentional control (Zikopoulos and Barbas, 2006 ; Béhuret et al, 2015 ; Wimmer et al, 2015 ). This layer sends extensive projections to thalamic nuclei (Mercer et al, 2005 ; Watts and Thomson, 2005 ; West et al, 2006 ; Zikopoulos and Barbas, 2006 ; Thomson, 2010 ) and to local circuit interneurons in cerebral cortex (Olsen et al, 2012 ; Tian et al, 2016 ). The corticothalamic connections are critical for top-down control of attentional processes (Miller and Cohen, 2001 ; Alitto and Usrey, 2003 ; Sherman, 2007 ; Wallace and Bertrand, 2013 ) and the corticocortical connections mediate cortical gain control (Olsen et al, 2012 ; Kim et al, 2016 ).…”