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"Reaction Time"
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Delayed response : the art of waiting from the ancient to the instant world
We have always been conscious of the wait for life-changing messages, whether it be the time it takes to receive a text message from your love, for a soldier's family to learn news from the front, or for a space probe to deliver data from the far reaches of the solar system. In this book in praise of wait times, award-winning author Jason Farman passionately argues that the delay between call and answer has always been an important part of the message. Traveling backward from our current era of Twitter and texts, Farman shows how societies have worked to eliminate waiting in communication and how they have interpreted those times' meanings. Exploring seven eras and objects of waiting--including pneumatic mail tubes in New York, Elizabethan wax seals, and Aboriginal Australian message sticks--Farman offers a new mindset for waiting. In a rebuttal to the demand for instant communication, Farman makes a powerful case for why good things can come to those who wait.
Book
Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers
Research has shown that psychedelics, such as lysergic acid diethylamide (LSD), have profound anti-inflammatory properties mediated by 5-HT2A receptor signaling, supporting their evaluation as a therapeutic for neuroinflammation associated with neurodegenerative disease.ObjectiveThis study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of orally repeated administration of 5 μg, 10 μg, and 20 μg LSD in older healthy individuals. In the current paper, we present safety, tolerability, pharmacokinetics, and pharmacodynamic measures that relate to safety, tolerability, and dose response.MethodsThis was a phase 1 double-blind, placebo-controlled, randomized study. Volunteers were randomly assigned to 1 of 4 dose groups (5 μg, 10 μg, 20 μg LSD, and placebo), and received their assigned dose on six occasions (i.e., every 4 days).ResultsForty-eight older healthy volunteers (mean age = 62.9 years) received placebo (n = 12), 5 μg (n = 12), 10 μg (n = 12), or 20 μg (n = 12) LSD. LSD plasma levels were undetectable for the 5 μg group and peak blood plasma levels for the 10 μg and 20 μg groups occurred at 30 min. LSD was well tolerated, and the frequency of adverse events was no higher than for placebo. Assessments of cognition, balance, and proprioception revealed no impairment.ConclusionsOur results suggest safety and tolerability of orally administered 5 μg, 10 μg, and 20 μg LSD every fourth day over a 21-day period and support further clinical development of LSD for the treatment and prevention of Alzheimer’s disease (AD).
Journal Article
Dopamine Modulates Reward-Related Vigor
Subjects routinely control the vigor with which they emit motoric responses. However, the bulk of formal treatments of decision-making ignores this dimension of choice. A recent theoretical study suggested that action vigor should be influenced by experienced average reward rate and that this rate is encoded by tonic dopamine in the brain. We previously examined how average reward rate modulates vigor as exemplified by response times and found a measure of agreement with the first suggestion. In the current study, we examined the second suggestion, namely the potential influence of dopamine signaling on vigor. Ninety healthy subjects participated in a double-blind experiment in which they received one of the following: placebo, L-DOPA (which increases dopamine levels in the brain), or citalopram (which has a selective, if complex, effect on serotonin levels). Subjects performed multiple trials of a rewarded odd-ball discrimination task in which we varied the potential reward over time in order to exercise the putative link between vigor and average reward rate. Replicating our previous findings, we found that a significant fraction of the variance in subjects' responses could be explained by our experimentally manipulated changes in average reward rate. Crucially, this relationship was significantly stronger under L-Dopa than under Placebo, suggesting that the impact of average reward levels on action vigor is indeed subject to a dopaminergic influence.
Journal Article
Effects of balance-based visual reaction time exercises on cognitive and physical performance in older adults: a randomized controlled trial
Technological approaches that promote cognitive-motor abilities through visual information have recently become increasingly prevalent. This study aims to verify the effects of balance-based visual reaction time exercises on physical and cognitive performance in older adults. In this randomized controlled trial, 31 participants (aged 71.70 ± 5.67 years) were randomly allocated into two groups. The intervention group (
n
= 16) was enrolled in a balanced-based visual reaction exercise program, and the control group (
n
= 15) in a functional balance exercise program. The participants were assessed both prior to and following the intervention. Primary outcomes included global cognitive function, assessed using the Montreal Cognitive Assessment (MoCA); executive function, measured through the Stroop Test; and reaction time, evaluated using the BlazePod system and the New Test. Secondary outcomes focused on physical performance and included the Five Times Sit-to-Stand Test (FTSS), Timed Up and Go Test (TUG), Four Square Step Test (FSST), Short Physical Performance Battery (SPPB), and the Falls Efficacy Scale (FES) to assess fear of falling. At reassessment, the intervention group exhibited a significantly faster reaction time and made fewer mistakes on the Stroop test compared to the control group (
p
< 0.05). The intervention group also exhibited better physical performance and less fear of falling (
p
< 0.05). However, no significant improvements were observed in global cognitive function, as measured by the Montreal Cognitive Assessment (MoCA), or in Stroop Interference scores (p
0.05). Two-model multiple linear regression analysis revealed that the changes in BlazePod reaction affected the improvement in TUG (β = 0.006, adjusted R
2
= 0.24) and FES (β = 0.013, adjusted R
2
= 0.15). In addition, the enhancement in FSST was influenced by changes in the BlazePod stroke (β=-0.585, Delta R
2
= 0.22). This study demonstrated that balance-based visual reaction time exercises significantly improved reaction time and physical performance in older adults, while no significant changes were observed in executive function measures. These findings highlight the potential of visually guided dual-task training as a feasible strategy to enhance functional outcomes in this population.
Journal Article
A caffeine-maltodextrin mouth rinse counters mental fatigue
Introduction
Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity that has negative implications on many aspects in daily life. Caffeine and carbohydrate ingestion have been shown to be able to reduce these negative effects of mental fatigue. Intake of these substances might however be less desirable in some situations (e.g., restricted caloric intake, Ramadan). Rinsing caffeine or glucose within the mouth has already been shown to improve exercise performance. Therefore, we sought to evaluate the effect of frequent caffeine-maltodextrin (CAF-MALT) mouth rinsing on mental fatigue induced by a prolonged cognitive task.
Methods
Ten males (age 23 ± 2 years, physical activity 7.3 ± 4.3 h/week, low CAF users) performed two trials. Participants first completed a Flanker task (3 min), then performed a 90-min mentally fatiguing task (Stroop task), followed by another Flanker task. Before the start and after each 12.5% of the Stroop task (eight blocks), subjects received a CAF-MALT mouth rinse (MR: 0.3 g/25 ml CAF: 1.6g/25 ml MALT) or placebo (PLAC: 25 ml artificial saliva).
Results
Self-reported mental fatigue was lower in MR (
p
= 0.017) compared to PLAC. Normalized accuracy (accuracy first block = 100%) was higher in the last block of the Stroop in MR (
p
= 0.032) compared to PLAC. P2 amplitude in the dorsolateral prefrontal cortex (DLPFC) decreased over time only in PLAC (
p
= 0.017).
Conclusion
Frequent mouth rinsing during a prolonged and demanding cognitive task reduces mental fatigue compared to mouth rinsing with artificial saliva.
Journal Article
Immediate and Long-Term Effects of Breathing Exercises on Reaction Time
Background and Objectives: The aim of this study was to investigate the immediate and long-term effects of breathing exercises on simple and choice reaction time. Materials and Methods: A total of 31 participants were included in the study. The participants were randomly divided into two groups. The intervention group (IG; n:16) received 12 sessions of breathing exercises for four weeks (three days a week), while the control group (CG; n:15) received no intervention. Both groups underwent the same assessments at the same times: at baseline, after the first exercise session, and after four weeks/after 12 exercise sessions. Reaction time was assessed using three conditions: choice reaction time (CRT) of the upper limb, auditory reaction time (ART), and visual reaction time (VRT) tests. The first assessment was applied at baseline. The second assessment measured the short-term effect of the breathing exercises after the study group received their first breathing exercise session. The third assessment, to determine the long-term effect, was repeated four weeks after the baseline (A4W) assessment after completing 12 breathing exercises. Results: There was no significant difference between the groups at baseline, immediately, and A4W (p < 0.05) for the VRT, ART, and CRT results with the dominant hand (DH), whereas a group-by-time interaction was found only for the visual reaction time results with the non-dominant hand (nDH) (p > 0.05). Conclusions: The results of this study, which included the evaluation of the immediate and long-term effects of breathing exercises on reaction time, showed an improvement in visual reaction time between the groups over time. In further studies, it is recommended to evaluate the changes and responses in the central nervous system with objective methods to reveal the effect of breathing exercises on reaction time more clearly.
Journal Article
Impulsiveness as a timing disturbance: neurocognitive abnormalities in attention-deficit hyperactivity disorder during temporal processes and normalization with methylphenidate
We argue that impulsiveness is characterized by compromised timing functions such as premature motor timing, decreased tolerance to delays, poor temporal foresight and steeper temporal discounting. A model illustration for the association between impulsiveness and timing deficits is the impulsiveness disorder of attention-deficit hyperactivity disorder (ADHD). Children with ADHD have deficits in timing processes of several temporal domains and the neural substrates of these compromised timing functions are strikingly similar to the neuropathology of ADHD. We review our published and present novel functional magnetic resonance imaging data to demonstrate that ADHD children show dysfunctions in key timing regions of prefrontal, cingulate, striatal and cerebellar location during temporal processes of several time domains including time discrimination of milliseconds, motor timing to seconds and temporal discounting of longer time intervals. Given that impulsiveness, timing abnormalities and more specifically ADHD have been related to dopamine dysregulation, we tested for and demonstrated a normalization effect of all brain dysfunctions in ADHD children during time discrimination with the dopamine agonist and treatment of choice, methylphenidate. This review together with the new empirical findings demonstrates that neurocognitive dysfunctions in temporal processes are crucial to the impulsiveness disorder of ADHD and provides first evidence for normalization with a dopamine reuptake inhibitor.
Journal Article
Role of Dopamine D2 Receptors in Human Reinforcement Learning
Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.
Journal Article
The acute effects of cocoa flavanols on temporal and spatial attention
In this study, we investigated how the acute physiological effects of cocoa flavanols might result in specific cognitive changes, in particular in temporal and spatial attention. To this end, we pre-registered and implemented a randomized, double-blind, placebo- and baseline-controlled crossover design. A sample of 48 university students participated in the study and each of them completed the experimental tasks in four conditions (baseline, placebo, low dose, and high-dose flavanol), administered in separate sessions with a 1-week washout interval. A rapid serial visual presentation task was used to test flavanol effects on temporal attention and integration, and a visual search task was similarly employed to investigate spatial attention. Results indicated that cocoa flavanols improved visual search efficiency, reflected by reduced reaction time. However, cocoa flavanols did not facilitate temporal attention nor integration, suggesting that flavanols may affect some aspects of attention, but not others. Potential underlying mechanisms are discussed.
Journal Article
Sequence learning in the human brain: A functional neuroanatomical meta-analysis of serial reaction time studies
Sequence learning underlies numerous motor, cognitive, and social skills. Previous models and empirical investigations of sequence learning in humans and non-human animals have implicated cortico-basal ganglia-cerebellar circuitry as well as other structures. To systematically examine the functional neuroanatomy of sequence learning in humans, we conducted a series of neuroanatomical meta-analyses. We focused on the serial reaction time (SRT) task. This task, which is the most widely used paradigm for probing sequence learning in humans, allows for the rigorous control of visual, motor, and other factors. Controlling for these factors (in sequence-random block contrasts), sequence learning yielded consistent activation only in the basal ganglia, across the striatum (anterior/mid caudate nucleus and putamen) and the globus pallidus. In contrast, when visual, motor, and other factors were not controlled for (in a global analysis with all sequence-baseline contrasts, not just sequence-random contrasts), premotor cortical and cerebellar activation were additionally observed. The study provides solid evidence that, at least as tested with the visuo-motor SRT task, sequence learning in humans relies on the basal ganglia, whereas cerebellar and premotor regions appear to contribute to aspects of the task not related to sequence learning itself. The findings have both basic research and translational implications.
•Using ALE, we synthesized the functional neuroanatomical data on sequence learning.•We focused on the widely used serial reaction time (SRT) task paradigm.•Sequence learning (sequence > random contrast) showed only basal ganglia activation.•This was found in the anterior/mid caudate and putamen, and in the globus pallidus.•Cerebellar/premotor activation was linked to other (visual/motor) SRT task factors.
Journal Article