Overall, it appears that feedback projections from PTV can exert excitatory and suppressive effects on spike-responses of area 19 neurons recorded from layers 3/4. It is possible that at least some of these effects are exerted via cortico-thalamic-thalamo-cortical loops (see Sherman, 2005; Sherman and Guillery, 2011). In the case of area 17 such loops would involve: PTV cortex—lateral posterior/pulvinar thalamic complex—area 17; in the case of area 19 it would involve: PTV cortex—lateral posterior/pulvinar thalamic complex—area 19 (Rosenquist, 1985; Dreher, 1986; Casanova et al., 1997; Piché et al., 2015). There is an important caveat to our conclusions due to the fact that we do not have information about the effects of inactivation of PTV on area 19 neurons in the superficial and deep layers.