In their original paper, Tadin et al.
(2003) proposed that this effect is a perceptual correlate of center-surround antagonism in neurons in visual cortex. This interpretation has broadly been supported by subsequent research (Churan, Khawaja, Tsui, & Pack,
2008; Glasser & Tadin,
2010; Neri & Levi,
2009; Pack, Hunter, & Born,
2005; Peterson, Li, & Freeman,
2006; Schwabe, Ichida, Shushruth, Mangapathy, & Angelucci,
2010; Tsui & Pack,
2011). Additionally, the effect has been repeatedly linked to alteration in GABA-ergic inhibitory cortical function. Betts and coworkers (Betts, Sekuler, & Bennett,
2009,
2012; Betts, Taylor, Sekuler, & Bennett,
2005) found much lower Surround Suppression Indices in older observers (mean age 68). Given that center-surround antagonism is thought to be mediated by inhibitory interneurons (Angelucci & Bressloff,
2006), they suggested that this was due to a decline in the efficacy of GABA-ergic cortical inhibitory mechanisms with age (Caspary, Hughes, & Ling,
2013; Leventhal, Wang, Pu, Zhou, & Ma,
2003; Poe, Linville, & Brunso-Bechtold,
2001). Golomb et al. (
2009) found that the Surround Suppression Index was reduced in patients with major depression, and linked this to dysfunction of GABA-ergic inhibition in this group (Luscher, Shen, & Sahir,
2011). Similarly, Tadin et al. (
2006) found that Surround Suppression Index was reduced in patients with severe schizophrenia, again linking this to GABA-ergic dysfunction (Wassef, Baker, & Kochan,
2003). In indirect support of the GABA-ergic hypothesis, GABA concentration measured with magnetic resonance spectroscopy is significantly correlated with a different psychophysical measure of surround suppression (Yoon et al.,
2010).