EMOTION AND AGEING · Neural substrates of emotion regulation across the lifespan

Neural substrates of emotion regulation across the lifespan

Brain imaging studies have identified a network of areas in the prefrontal cortex (PFC) underlying the voluntary regulation of negative information, including the dorsolateral and dorsomedial pre-frontal cortex. The objective of this study was to investigate the neural substrates underlying the effects of positive or negative framing of verbal cues following the presentation of negative images, and to determine the extent to which the ability of individuals to respond may change across the lifespan. It was predicted that positive framing would engage lateral and ventromedial PFC and decrease subcortical brain regions involved in emotion responses, including the insula and amygdala, whilst negative framing would show the opposite effect, increasing the activation in the subcortical limbic structures. As older adults have more effective emotion regulatory processes engaging sections of the medial PFC, it was further predicted that when negative images were framed positively, age would be negatively associated with activation in the lateral PFC and positively associated with brain activation in the medial PFC. An FMRI study tested the paradigm on 17 University of Reading students. For 8 seconds participants were presented with emotional images, selected from the International Affective Picture System (IAPS, Bradley and Lang, 2005; Fig 1), which were either negative or neutral. Whilst the images were shown the participants heard a short commentary which could be positively framed, emphasising a positive outcome, or negatively framed, emphasising a negative outcome. A control condition was also presented in which the auditory cue described the scene factually. The soundtracks were matched for duration and word count across all conditions. At the end of each trial participants were asked to rate how negative or neutral they found the picture on a four-point scale, ranging from neutral to strongly negative. Consistent with prior FMRI studies on voluntary emotion regulation, clusters were found in the medial and lateral PFC, with positive cues associated with a higher response than the control condition. Behavioural data was collected during and after the task which indicated that positive cues significantly dampened the impact of the negative pictures, relative to the control condition, with subjective ratings positively associated with responses in the ventromedial PFC (Fig 2). These data highlighted that directed positive reappraisal of negative information involves the overlap with those underlying participant-generated regulatory strategies. The second FMRI study recruited 44 participants aged 25 to 75 years, of whom 38 completed the MRI session. All participants were tested for cognitive function using a battery of standard neuropsychological and cognitive tasks, selected on the basis that they correlated with the lateral prefrontal regions involved in emotion regulation. In addition, using self-report based questionnaires, well-being was assessed. Brain images were acquired using a 3-Tesla Siemens Trio MRI scanner whilst participants were presented with pictures accompanied by auditory cues as for the first FMRI study (see Fig. 1). Pupil size of the participants was also measured to ascertain that the framing conditions engaged a similar level of task engagement. The pupil dilation was found to increase after the presentation of the verbal cue, reflecting task engagement, but the framing conditions had no differential impact on pupil size (p>.05).

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