“…Second, it is well-established that the central nervous system includes at least two distinct forms of GABAergic inhibition: a tonic one involving (mostly extrasynaptic) metabotropic GABA A receptors, and a phasic one involving (mostly intrasynaptic) ionotropic GABA B receptors. Although resting MRS-GABA signal is thought to predominantly reflect the former ( Stagg, Bestmann, Constantinescu, Moreno Moreno, Allman, Mekle, Woolrich, Near, Johansen-Berg, Rothwell, 2011 , Stagg, Best, Stephenson, O’Shea, Wylezinska, Kincses, Morris, Matthews, Johansen-Berg, 2009 ), the latter may also explain some of the inter-individual variance in signal, and is known to play a role in adaptation memory ( Johnstone et al., 2021 ). The extent to which tonic versus phasic GABAergic signalling contributes to our findings therefore remains an open question for future research.…”