Time in the motor cortex: Motor evoked potentials track foreperiod duration without concurrent movement

Anaesthetics and time perception: A review

Consciousness requires subjective experience in the "now." Establishing "now," however, necessitates temporal processing. In the current article, we review one method of altering consciousness, anaesthetic drug administration, and its effects on perceived duration. We searched PubMed, PsycInfo, and ScienceDirect databases, and article reference sections, for combinations of anaesthetic drugs and time perception tasks, finding a total of 36 articles which met our inclusion criteria. We categorised these articles with regard to whether they altered the felt passage of time, short or long interval timing, or were motor timing tasks. We found that various drugs alter the perceived passage of time; ketamine makes time subjectively slow down while GABAergic drugs make time subjectively speed up. At a short interval there is little established evidence of a shift in time perception, though temporal estimates appear more variable. Similarly, when asked to use time to optimise responses (i.e., in motor timing tasks), various anaesthetic agents make timing more variable. Longer durations are estimated as lasting longer than their objective duration, though there is some variation across articles in this regard. We conclude by proposing further experiments to examine time perception under altered states of consciousness and ask whether it is possible to perceive the passage of time of events which do not necessarily reach the level of conscious perception. The variety of methods used raises the need for more systematic investigations of time perception under anaesthesia. We encourage future investigations into the overlap of consciousness and time perception to advance both fields.

Corticospinal excitability reductions during action preparation and action stopping in humans: Different sides of the same inhibitory coin?

Motor functions and cognitive processes are closely associated with each other. In humans, this linkage is reflected in motor system state changes both when an action must be prepared and stopped. Single-pulse transcranial magnetic stimulation showed that both action preparation and action stopping are accompanied by a reduction of corticospinal excitability, referred to as preparatory and response inhibition, respectively. While previous efforts have been made to describe both phenomena extensively, an updated and comprehensive comparison of the two phenomena is lacking. To ameliorate such deficit, this review focuses on the role and interpretation of single-coil (single-pulse and paired-pulse) and dual-coil TMS outcome measures during action preparation and action stopping in humans. To that effect, it aims to identify commonalities and differences, detailing how TMS-based outcome measures are affected by states, traits, and psychopathologies in both processes. Eventually, findings will be compared, and open questions will be addressed to aid future research.

On doing multi-act arithmetic: A multitrait-multimethod approach of performance dimensions in integrated multitasking

Here we present a systematic plan to the experimental study of test-retest reliability in the multitasking domain, adopting the multitrait-multimethod (MTMM) approach to evaluate the psychometric properties of performance in Düker-type speeded multiple-act mental arithmetic. These form of tasks capacitate the experimental analysis of integrated multi-step processing by combining multiple mental operations in flexible ways in the service of the overarching goal of completing the task. A particular focus was on scoring methodology, particularly measures of response speed variability. To this end, we present data of two experiments with regard to (a) test-retest reliability, (b) between-measures correlational structure, (c) and stability (test-retest practice effects). Finally, we compared participants with high versus low performance variability to assess ability-related differences in measurement precision (typically used as proxy to "simulate" patient populations), which is especially relevant in the applied fields of clinical neuropsychology. The participants performed two classic integrated multi-act arithmetic tasks, combining addition and verification (Exp. 1) and addition and comparison (Exp. 2). The results revealed excellent test-retest reliability for the standard and the variability measures. The analysis of between-measures correlational structure revealed the typical pattern of convergent and discriminant relationships, and also, that absolute response speed variability was highly correlated with average speed (r > 0.85), indicating that these measures mainly deliver redundant information. In contrast, speed-adjusted (relativized) variability revealed discriminant validity being correlated to a much lesser degree with average speed, indicating that this measure delivers additional information not already provided by the speed measure. Furthermore, speed-adjusted variability was virtually unaffected by test-retest practice, which makes this measure interesting in situations with repeated testing.