Validation of food diaries as measures of dietary behaviour change.

This study aimed to validate the ability of a 24-h food diary (the DIET-24) to accurately detect change in children's fruit and vegetable consumption at school snack time following implementation of the Food Dudes healthy eating intervention. Participants were 4- to 9-year-old children from two primary schools in England. There were 148 participants in the intervention school and 43 participants in the no intervention control school. For each child, snack-time fruit and vegetable consumption was measured separately by weight (grammes), and compared with teachers' estimates (to the nearest half portion) using the DIET-24. Both consumption measures were taken at T1 (pre-intervention) and T2 (post-intervention). At each time-point, Spearman rank correlations between the two measures were low to moderate, but significant. However, when compared with weighed measures, the DIET-24 did not always accurately detect significant changes in children's fruit and vegetable consumption following the intervention. To provide sensitive measures of behaviour change, it is important that dietary measures assess as accurately as possible the amount of food consumed, rather than, as is often the case, rely on all-or-none portion estimates. This issue is important for the establishment of a reliable evidence-base for healthy eating interventions.

Effects of motor intention on the perception of somatosensory events: a behavioural and functional magnetic resonance imaging study.

The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of "active touch", and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal "forward" model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.

Modulation of somatosensory perception by motor intention.

The intention to execute a movement can modulate our perception of sensory events; however, theoretical accounts of these effects, and also empirical data, are often contradictory. We investigated how perception of a somatosensory stimulus differed according to whether it was delivered to a limb being prepared for movement or to a nonmoving limb. Our results demonstrate that individuals perceive a somatosensory stimulus delivered to the "moving" limb as occurring significantly later than when an identical stimulus is delivered to a "nonmoving" limb. Furthermore, human brain imaging (fMRI) analyses demonstrate that this modulation is accompanied by a significant decrease in BOLD signal in the right parietal operculum (SII) for stimuli delivered to the moving limb. These results indicate that during movement preparation a network of premotor brain areas may facilitate movement execution by attenuating the processing of behaviorally irrelevant signals within higher-order secondary somatosensory (SII) areas.