Prepulse inhibition of the human startle eye blink response by visual food cues

We present a new paradigm to investigate cognitive processing of food cues. The study assessed if pictures of food induce prepulse inhibition (PPI) of startle eye blink, and if any such effect is sensitive to food deprivation. In a balanced cross-over design, 16 healthy male volunteers (mean age: 29 years) were tested on 2 days 1 week apart, either after a period of normal food intake (NFI) or after a 24 h period of food restriction (RFI). On each experimental day, 80 control and 20 food pictures (slides) were displayed. Noise stimuli were presented 250 ms after slide onset. Startle responses were assessed by EMG recordings of the right M. orbicularis oculi. Startle elicited during dark inter-slide periods served as control responses to calculate PPI effects. The arousing content of each picture was rated by all subjects at the end of the session. The perceived arousal effect of control slides was strongly related to their PPI effect; no impact of food access status on this association was detectable. After NFI, food slides significantly induced PPI of startle (mean: -14.5%). After RFI, arousal ratings for food pictures increased but PPI did not. These results are evidence for a pre-attentive mechanism operative in the processing of visual food cues.