Meditation-induced cognitive-control states regulate working memory task performance.

Single-bout focused-attention meditation (FAM) and open-monitoring meditation (OMM) are assumed to bias metacontrol states towards more persistent versus more flexible processing, respectively. In Experiment 1, we tested whether monitoring and updating of working memory (WM) representations in an N-back task with high (3-back), medium (2-back), and low (1-back) WM demands (varied within participants) is affected by preceding single-bout FAM or OMM meditation (varied between participants and compared with a control group). The results showed that FAM promotes WM performance in the medium (2-back), but not in the high (3-back) or low (1-back) demand condition, whereas OMM did not affect WM performance. A replication of the 2-back condition only (Experiment 2) showed no meditation effect, but a replication of the 3-back condition only (Experiment 3) produced a similar pattern as the 2-back condition in Experiment 1, with FAM promoting performance compared with OMM and the control condition. Taken together, these findings suggest that the single-bout FAM does promote WM performance but only if the capacity demands are neither too high nor too low.

Metacontrol and body ownership: divergent thinking increases the virtual hand illusion.

The virtual hand illusion (VHI) paradigm demonstrates that people tend to perceive agency and bodily ownership for a virtual hand that moves in synchrony with their own movements. Given that this kind of effect can be taken to reflect self-other integration (i.e., the integration of some external, novel event into the representation of oneself), and given that self-other integration has been previously shown to be affected by metacontrol states (biases of information processing towards persistence/selectivity or flexibility/integration), we tested whether the VHI varies in size depending on the metacontrol bias. Persistence and flexibility biases were induced by having participants carry out a convergent thinking (Remote Associates) task or divergent-thinking (Alternate Uses) task, respectively, while experiencing a virtual hand moving synchronously or asynchronously with their real hand. Synchrony-induced agency and ownership effects were more pronounced in the context of divergent thinking than in the context of convergent thinking, suggesting that a metacontrol bias towards flexibility promotes self-other integration.

Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention.

In a randomized, double-blind, and placebo-controlled experiment, the acute effects of gamma-aminobutyric acid (GABA) supplementation on temporal and spatial attention in young healthy adults were investigated. A hybrid two-target rapid serial visual presentation task was used to measure temporal attention and integration. Additionally, a visual search task was used to measure the speed and accuracy of spatial attention. While temporal attention depends primarily on the distribution of limited attentional resources across time, spatial attention represents the engagement and disengagement by relevant and irrelevant stimuli across the visual field. Although spatial attention was unaffected by GABA supplementation altogether, we found evidence supporting improved performance in the temporal attention task. The attentional blink was numerically, albeit not significantly, attenuated at Lag 3, and significantly fewer order errors were committed at Lag 1, compared to the placebo condition. No effect was found on temporal integration rates. Although there is controversy about whether oral GABA can cross the blood-brain barrier, our results offer preliminary evidence that GABA intake might help to distribute limited attentional resources more efficiently, and can specifically improve the identification and ordering of visual events that occur in close temporal succession.

Meditation and Metacontrol.

In addition to longer-term engagement in meditation, the past years have seen an increasing interest in the impact of single bouts of meditation on cognition. In this hypothesis and theory article, we adopt the distinction between focused-attention meditation (FAM) and open-monitoring meditation (OMM) and argue that these different types of meditation have different, to some degree, opposite impact on cognitive processes. We discuss evidence suggesting that single bouts of FAM and OMM are sufficient to bias cognitive control styles towards more versus less top-down control, respectively. We conclude that all meditation techniques are not equal and that successful meditation-based intervention requires the theoretically guided selection of the best-suited technique.

More attentional focusing through binaural beats: evidence from the global-local task.

A recent study showed that binaural beats have an impact on the efficiency of allocating attention over time. We were interested to see whether this impact affects attentional focusing or, even further, the top-down control over irrelevant information. Healthy adults listened to gamma-frequency (40 Hz) binaural beats, which are assumed to increase attentional concentration, or a constant tone of 340 Hz (control condition) for 3 min before and during a global-local task. While the size of the congruency effect (indicating the failure to suppress task-irrelevant information) was unaffected by the binaural beats, the global-precedence effect (reflecting attentional focusing) was considerably smaller after gamma-frequency binaural beats than after the control condition. Our findings suggest that high-frequency binaural beats bias the individual attentional processing style towards a reduced spotlight of attention.

A single bout of meditation biases cognitive control but not attentional focusing: Evidence from the global-local task.

Recent studies show that a single bout of meditation can impact information processing. We were interested to see whether this impact extends to attentional focusing and the top-down control over irrelevant information. Healthy adults underwent brief single bouts of either focused attention meditation (FAM), which is assumed to increase top-down control, or open monitoring meditation (OMM), which is assumed to weaken top-down control, before performing a global-local task. While the size of the global-precedence effect (reflecting attentional focusing) was unaffected by type of meditation, the congruency effect (indicating the failure to suppress task-irrelevant information) was considerably larger after OMM than after FAM. Our findings suggest that engaging in particular kinds of meditation creates particular cognitive-control states that bias the individual processing style toward either goal-persistence or cognitive flexibility.

Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A review.

Consuming the amino-acid tyrosine (TYR), the precursor of dopamine (DA) and norepinephrine (NE), may counteract decrements in neurotransmitter function and cognitive performance. However, reports on the effectiveness of TYR supplementation vary considerably, with some studies finding beneficial effects, whereas others do not. Here we review the available cognitive/behavioral studies on TYR, to elucidate whether and when TYR supplementation can be beneficial for performance. The potential of using TYR supplementation to treat clinical disorders seems limited and its benefits are likely determined by the presence and extent of impaired neurotransmitter function and synthesis. Likewise, the potential of TYR supplementation for enhancing physical exercise seems minimal as well, perhaps because the link between physical exercise and catecholamine function is mediated by many other factors. In contrast, TYR does seem to effectively enhance cognitive performance, particularly in short-term stressful and/or cognitively demanding situations. We conclude that TYR is an effective enhancer of cognition, but only when neurotransmitter function is intact and DA and/or NE is temporarily depleted.

Meditation-induced states predict attentional control over time.

Meditation is becoming an increasingly popular topic for scientific research and various effects of extensive meditation practice (ranging from weeks to several years) on cognitive processes have been demonstrated. Here we show that extensive practice may not be necessary to achieve those effects. Healthy adult non-meditators underwent a brief single session of either focused attention meditation (FAM), which is assumed to increase top-down control, or open monitoring meditation (OMM), which is assumed to weaken top-down control, before performing an Attentional Blink (AB) task - which assesses the efficiency of allocating attention over time. The size of the AB was considerably smaller after OMM than after FAM, which suggests that engaging in meditation immediately creates a cognitive-control state that has a specific impact on how people allocate their attention over time.

Improved human visuomotor performance and pupil constriction after choline supplementation in a placebo-controlled double-blind study.

Only few nutrients are known to enhance cognition. Here we explore whether visuomotor performance can be improved through the intake of the nutrient choline, an essential chemical compound in a vertebrate's diet. Choline is abundant in for example eggs and shrimps and many animal studies suggest that it serves as a cognitive enhancer. As choline is important for the communication between motor neurons and the control of skeletal muscles, we assumed that choline supplementation may have positive effects on action coordination in humans. A group of twenty-eight individuals ingested two grams of choline bitartrate or a placebo in two separate sessions. Seventy minutes post ingestion, participants performed a visuomotor aiming task in which they had to rapidly hit the centers of targets. Results showed that participants hit targets more centrally after choline supplementation. Pupil size (a cognition-sensitive biomarker) also significantly decreased after choline intake and correlated positively with the hit distance to the targets and the number of target misses, and negatively with reaction times. These findings point to a choline-induced bias towards action precision in the trade-off between speed and accuracy. The changes in pupil size suggest that choline uptake alters cholinergic functions in the nervous system.

Meditation-induced cognitive-control states regulate response-conflict adaptation: Evidence from trial-to-trial adjustments in the Simon task.

Here we consider the possibility that meditation has an immediate impact on information processing. Moreover, we were interested to see whether this impact affects attentional input control, as previous observations suggest, or the handling of response conflict. Healthy adults underwent a brief single session of either focused attention meditation (FAM), which is assumed to increase top-down control, or open monitoring meditation (OMM), which is assumed to weaken top-down control, before performing a Simon task-which assesses conflict-resolution efficiency. While the size of the Simon effect (reflecting the efficiency of handling response conflict) was unaffected by type of meditation, the amount of dynamic behavioral adjustments (i.e., trial-to-trial variability of the Simon effect: the Gratton effect) was considerably smaller after OMM than after FAM. Our findings suggest that engaging in meditation instantly creates a cognitive-control state that has a specific impact on conflict-driven control adaptations.

Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance.

Tyrosine (TYR), an amino acid found in various foods, has been shown to increase dopamine (DA) levels in the brain. Recent studies have provided evidence that TYR supplementation can improve facets of cognitive control in situations with high cognitive demands. Here we investigated whether TYR promotes cognitive flexibility, a cognitive-control function that is assumed to be modulated by DA. We tested the effect of TYR on proactive vs. reactive control during task switching performance, which provides a relatively well-established diagnostic of cognitive flexibility. In a double-blind, randomized, placebo-controlled design, 22 healthy adults performed in a task-switching paradigm. Compared to a neutral placebo, TYR promoted cognitive flexibility (i.e. reduced switching costs). This finding supports the idea that TYR can facilitate cognitive flexibility by repleting cognitive resources.

Food for creativity: tyrosine promotes deep thinking.

Anecdotal evidence suggests that creative people sometimes use food to overcome mental blocks and lack of inspiration, but empirical support for this possibility is still lacking. In this study, we investigated whether creativity in convergent- and divergent-thinking tasks is promoted by the food supplement L-Tyrosine (TYR)-a biochemical precursor of dopamine, which is assumed to drive cognitive control and creativity. We found no evidence for an impact of TYR on divergent thinking ("brainstorming") but it did promote convergent ("deep") thinking. As convergent thinking arguably requires more cognitive top-down control, this finding suggests that TYR can facilitate control-hungry creative operations. Hence, the food we eat may affect the way we think.

Focused attention, open monitoring and loving kindness meditation: effects on attention, conflict monitoring, and creativity - A review.

Meditation is becoming increasingly popular as a topic for scientific research and theories on meditation are becoming ever more specific. We distinguish between what is called focused Attention meditation, open Monitoring meditation, and loving kindness (or compassion) meditation. Research suggests that these meditations have differential, dissociable effects on a wide range of cognitive (control) processes, such as attentional selection, conflict monitoring, divergent, and convergent thinking. Although research on exactly how the various meditations operate on these processes is still missing, different kinds of meditations are associated with different neural structures and different patterns of electroencephalographic activity. In this review we discuss recent findings on meditation and suggest how the different meditations may affect cognitive processes, and we give suggestions for directions of future research.

Eating to stop: tyrosine supplementation enhances inhibitory control but not response execution.

Animal studies and research in humans have shown that the supplementation of tyrosine, or tyrosine-containing diets, increase the plasma tyrosine and enhance brain dopamine (DA). However, the strategy of administering tyrosine (and the role of DA therein) to enhance cognition is unclear and heavily debated. We studied, in a healthy population, whether tyrosine supplementation improves stopping overt responses, a core cognitive-control function. In a double-blind, placebo-controlled, within-subject design, one hour following the administration of tyrosine (corresponding to the beginning of the 1h-peak of the plasma concentration) or placebo, participants performed a stop-signal task-which taps into response inhibition and response execution speed. Participants in the Tyrosine condition were more efficient in inhibiting unwanted action tendencies but not in reacting to go signals. This is the first demonstration that the supplementation of tyrosine selectively targets, and reliably improves the ability to stop overt responses.

Working memory reloaded: tyrosine repletes updating in the N-back task.

In this study we tested the idea that the food supplement l-Tyrosine (TYR) repletes resources required for cognitive-control operations. We investigated whether the "updating" (and monitoring) of working memory (WM) representations, a key cognitive-control function, can be promoted by administering TYR, the biochemical precursor of dopamine. Participants performed an N-back task where we compared the WM-demanding 2-back condition with the WM-undemanding 1-back condition. As expected, TYR promoted performance in the more demanding (2-back) but not in the easier (1-back) condition, suggesting that TYR selectively targets cognitive-control operations. This result suggests that TYR can replete cognitive resources when more control is needed and, more generally, that food can act as a cognitive enhancer.

Khat use is associated with increased response conflict in humans.

OBJECTIVE: Khat consumption has become a worldwide phenomenon broadening from Eastern Africa and the south west of the Arabian Peninsula to ethnic communities in the rest of the world. Only few studies have systematically looked into cognitive impairments in khat users. We studied whether khat use is associated with changes in the emergence and resolution of response conflict, a central cognitive control function. METHOD: Khat users (n = 16) and khat-free controls (n = 16) were matched in terms of sex, ethnicity, socio-economical situation, age, alcohol and cannabis consumption, and IQ (Raven's Progressive Matrices). Groups were tested on response conflict, as measured by the Simon task. RESULTS: Khat users performed significantly slower than controls and were more strongly affected by stimulus-induced response conflict. CONCLUSIONS: Khat use is associated with specific impairments in behavioral control: general slowing and less efficient resolution of response conflicts, which is likely to impair decision making in everyday life.

Meditate to create: the impact of focused-attention and open-monitoring training on convergent and divergent thinking.

The practice of meditation has seen a tremendous increase in the western world since the 60s. Scientific interest in meditation has also significantly grown in the past years; however, so far, it has neglected the idea that different type of meditations may drive specific cognitive-control states. In this study we investigate the possible impact of meditation based on focused-attention (FA) and meditation based on open-monitoring (OM) on creativity tasks tapping into convergent and divergent thinking. We show that FA meditation and OM meditation exert specific effect on creativity. First, OM meditation induces a control state that promotes divergent thinking, a style of thinking that allows many new ideas of being generated. Second, FA meditation does not sustain convergent thinking, the process of generating one possible solution to a particular problem. We suggest that the enhancement of positive mood induced by meditating has boosted the effect in the first case and counteracted in the second case.