Effects of left dlPFC modulation on social cognitive processes following food sampling

The dorsolateral prefrontal cortex (dlPFC) plays a central role in the inhibition of eating, but also the modulation of conscious thought processes that might precede, accompany or follow initial food tasting. The latter might be particularly important to the extent that post-tasting cognitions may drive prolonged eating beyond the satiety point. However, we know very little about the effect of the dlPFC on conation following initial food sampling. This investigation compared the effects of dlPFC attenuation using repetitive transcranial magnetic stimulation (rTMS) on social cognition following (Study 1) and prior to (Study 2) a food consumption opportunity.

In Study 1, participants (N = 21; M_age = 21 years) were randomized to active or sham continuous theta-burst stimulation (cTBS; an inhibitory variant of rTMS) targeting the left dlPFC followed by an interference task. Participants subsequently completed measures of attitudes, norms and perceived control following a mock taste test. In Study 2, a second sample of right handed participants (N = 37; M_age = 21 years) were assigned to active or sham cTBS, followed by an interference task and two measures of attitudes (implicit and explicit), both assessed prior to the same taste test paradigm.

In Study 1, findings revealed a reliable effect of cTBS on post-tasting attitudes (t(1,19) = 3.055, p = .007; d = 1.34), such that attitudes towards calorie dense snack foods were significantly more positive following active stimulation than following sham stimulation. Similar effects were found for social norms (t(1,19) = 3.024, p = .007, d = 1.31) and perceived control (t(1,20) = 19.247, p < .001, d = 0.50). In Study 2, no effects of cTBS were observed on pre-consumption attitudes, despite reliable effects on interference scores and subsequent consumption.

The left dlPFC may selectively modulate facilitative social cognition following initial food sampling (but not pre-consumption).