Tonya L. Jacobs

The ability to focus one's attention underlies success in many everyday tasks, but voluntary attention cannot be sustained for extended periods of time. In the laboratory, sustained-attention failure is manifest as a decline in perceptual sensitivity with increasing time on task, known as the vigilance decrement. We investigated improvements in sustained attention with training (approximately 5 hr/day for 3 months), which consisted of meditation practice that involved sustained selective attention on a chosen stimulus (e.g., the participant's breath). Participants were randomly assigned either to receive training first (n = 30) or to serve as waiting-list controls and receive training second (n = 30). Training produced improvements in visual discrimination that were linked to increases in perceptual sensitivity and improved vigilance during sustained visual attention. Consistent with the resource model of vigilance, these results suggest that perceptual improvements can reduce the resource demand imposed by target discrimination and thus make it easier to sustain voluntary attention.

We examined the impact of training-induced improvements in self-regulation, operationalized in terms of response inhibition, on longitudinal changes in self-reported adaptive socioemotional functioning. Data were collected from participants undergoing 3 months of intensive meditation training in an isolated retreat setting (Retreat 1) and a wait-list control group that later underwent identical training (Retreat 2). A 32-min response inhibition task (RIT) was designed to assess sustained self-regulatory control. Adaptive functioning (AF) was operationalized as a single latent factor underlying self-report measures of anxious and avoidant attachment, mindfulness, ego resilience, empathy, the five major personality traits (extroversion, agreeableness, conscientiousness, neuroticism, and openness to experience), difficulties in emotion regulation, depression, anxiety, and psychological well-being. Participants in Retreat 1 improved in RIT performance and AF over time whereas the controls did not. The control participants later also improved on both dimensions during their own retreat (Retreat 2). These improved levels of RIT performance and AF were sustained in follow-up assessments conducted approximately 5 months after the training. Longitudinal dynamic models with combined data from both retreats showed that improvement in RIT performance during training influenced the change in AF over time, which is consistent with a key claim in the Buddhist literature that enhanced capacity for self-regulation is an important precursor of changes in emotional well-being.

1. Vasodilatation initiated by contracting skeletal muscle 'ascends' from the arteriolar network to encompass feed arteries. Acetylcholine delivery from a micropipette onto a feed artery evokes hyperpolarisation at the site of application; this signal can conduct through gap junctions along the endothelium to produce vasodilatation. We tested whether conduction along the endothelium contributes to the ascending vasodilatation that occurs in response to muscular exercise. 2. In anaesthetised hamsters, a feed artery (resting diameter 64 +/- 4 microm) supplying the retractor muscle was either stimulated by local microiontophoretic application of acetylcholine or the muscle was contracted rhythmically (once per 2 s, 1-2 min), before and after light-dye treatment (LDT) to disrupt the endothelial cells within a 300 microm-long segment located midway along the vessel. Endothelial cell damage with LDT was confirmed by the local loss of vasodilatation in response to acetylcholine and labelling with propidium iodide. Local vasodilatation in response to acetylcholine applied 500 microm proximal (upstream) or distal (downstream) to the central segment with LDT remained intact. 3. Before LDT, vessel diameter increased by more than 30 % along the entire feed artery (observed 1000 microm upstream from the retractor muscle) in response to distal acetylcholine or muscle contractions. Following LDT, vasodilatation in response to acetylcholine and to muscle contractions encompassed the distal segment but did not travel through the region of endothelial cell damage. At the upstream site, wall shear rate (and luminal shear stress) increased more than 3-fold, with no change in vessel diameter. Thus, flow-induced vasodilatation did not occur. 4. In response to muscle contractions, feed artery blood flow increased nearly 6-fold; this hyperaemic response was reduced by half following the loss of ascending vasodilatation. 5. These findings indicate that rhythmic contractions of skeletal muscle can initiate the conduction of a signal along the endothelium. We propose that this signalling pathway underlies ascending vasodilatation and promotes the full expression of exercise hyperaemia.

The capacity to focus one's attention for an extended period of time can be increased through training in contemplative practices. However, the cognitive processes engaged during meditation that support trait changes in cognition are not well characterized. We conducted a longitudinal wait-list controlled study of intensive meditation training. Retreat participants practiced focused attention (FA) meditation techniques for three months during an initial retreat. Wait-list participants later undertook formally identical training during a second retreat. Dense-array scalp-recorded electroencephalogram (EEG) data were collected during 6 min of mindfulness of breathing meditation at three assessment points during each retreat. Second-order blind source separation, along with a novel semi-automatic artifact removal tool (SMART), was used for data preprocessing. We observed replicable reductions in meditative state-related beta-band power bilaterally over anteriocentral and posterior scalp regions. In addition, individual alpha frequency (IAF) decreased across both retreats and in direct relation to the amount of meditative practice. These findings provide evidence for replicable longitudinal changes in brain oscillatory activity during meditation and increase our understanding of the cortical processes engaged during meditation that may support long-term improvements in cognition.