Timing dysfunctions in schizophrenia as measured by a repetitive finger tapping task

Schizophrenia may be associated with a fundamental disturbance in the temporal coordination of information processing in the brain, leading to classic symptoms of schizophrenia such as thought disorder and disorganized and contextually inappropriate behavior. Although a variety of behavioral studies have provided strong evidence for perceptual timing deficits in schizophrenia, no study to date has directly examined overt temporal performance in schizophrenia using a task that differentially engages perceptual and motor-based timing processes. The present study aimed to isolate perceptual and motor-based temporal performance in individuals diagnosed with schizophrenia using a repetitive finger-tapping task that has previously been shown to differentially engage brain regions associated with perceptual and motor-related timing behavior. Thirty-two individuals with schizophrenia and 31 non-psychiatric control participants completed the repetitive finger-tapping task, which required participants to first tap in time with computer-generated tones separated by a fixed intertone interval (tone-paced tapping), after which the tones were discontinued and participants were required to continue tapping at the established pace (self-paced tapping). Participants with schizophrenia displayed significantly faster tapping rates for both tone- and self-paced portions of the task compared to the non-psychiatric group. Individuals diagnosed with schizophrenia also displayed greater tapping variability during both tone- and self-paced portions of the task. The application of a mathematical timing model further indicated that group differences were primarily attributable to increased timing – as opposed to task implementation – difficulties in the schizophrenia group, which is noteworthy given the broad range of impairments typically associated with the disorder. These findings support the contention that schizophrenia is associated with a broad range of timing difficulties, including those associated with time perception as well as time production.     

Perfect Phase Correction in Synchronization With Slow Auditory Sequences

Phase correction during synchronization (finger tapping) with an isochronous auditory sequence is typically imperfect, requiring several taps to complete. However, two independent hypotheses predict that phase correction should approach perfection when the sequence tempo is slow. The present results confirm this prediction. The experiment used a phase perturbation method and a group of musically trained participants. As the sequence interonset interval increased from 300 to 1200 ms, the phase correction response to perturbations increased and approached instantaneous phase resetting between 700 and 1200 ms, depending on the individual. A possible explanation of this finding is that emergent timing of the periodic finger movement vanishes as the movement frequency decreases and thus ceases to compete with event-based timing.     

Perturbations in Action Goal Influence Bimanual Grasp Posture Planning

The authors examined the effects of perturbations in action goal on bimanual grasp posture planning. Sixteen participants simultaneously reached for 2 cylinders and placed either the left or the right end of the cylinders into targets. As soon as the participants began their reaching movements, a secondary stimulus was triggered, which indicated whether the intended action goal for the left or right hand had changed. Overall, the tendency for a single hand to select end-state comfort compliant grasp postures was higher for the nonperturbed condition compared to both the perturbed left and perturbed right conditions. Furthermore, participants were more likely to plan their movements to ensure end-state comfort for both hands during nonperturbed trials, than perturbed trials, especially object end-orientation conditions that required the adoption of at least one underhand grasp posture to satisfy bimanual end-state comfort. Results indicated that when the action goal of a single object was perturbed, participants attempted to reduce the cognitive costs associated with grasp posture replanning by maintaining the original grasp posture plan, and tolerating grasp postures that result in less controllable final postures.     

Practice Effects in Bimanual Force Control: Does Age Matter?

ABSTRACT

The authors examined age-related differences in fine motor control during a bimanual coordination task. The task required the modulation of fingertip forces in the precision grip according to a visually presented sinusoidal antiphase pattern (force range 2–12 N; frequency 0.2 Hz). Thirty-four right-handed participants of three age groups (young, early middle-aged, and late middle-aged) practiced 30 trials of the task. Accuracy and variability of relative timing and relative forces at minima and maxima of the sine wave were analyzed for hand–hand and hand–stimulus couplings and compared between age groups. Analysis showed for relative timing and force weaker hand–hand than hand–stimulus coupling as well as lower accuracy and higher variability for minima as compared to maxima. Further, we analyzed practice effects by comparing the first and last trials and characterized the course of practice by detecting the transition of a steeper to a shallower acquisition slope for the different age groups. Late middle-aged participants demonstrated poorer performance than both other groups for all parameters. All groups improved performance to a similar amount. However, an age-related difference in acquisition strategy is visible. Late middle-aged participants seemed to have focused on improvement of force amplitude, whereas young and early middle-aged focused on timing.     

Does Handedness Determine Which Hand Leads in a Bimanual Task?

Right- and left-handers (n = 16 in each group) were tested on a bimanual circle task that required drawing either in the same direction (parallel) or in a mirror symmetrical coordination mode with the two hands. The authors' primary purposes were to examine the effect of circle direction on within-hand and between-hands variables and to determine whether the relation between hand lead and coordination mode (parallel or mirror symmetrical) differs for left- and right-handers. A strong relation was found between lead hand and movement condition, which depended on the direction of the movements and whether the task was parallel or mirror symmetrical. The pattern of results was similar for left-and right-handers on parallel tasks, but group differences were found with respect to mirror symmetrical tasks. At odds with the general claim that the dominant hand leads, the present results indicated that hand dominance does not generally determine which hand leads.     

Motor Planning Influences the Perceived Timing of Vibrotactile Stimuli in an Amplitude-Dependent Manner

The authors characterized how motor planning influences temporal order judgment (TOJ) tasks. They examined this by applying vibrotactile stimulation during the planning stages of a bimanual arm movement that would bring the arms into a crossed configuration. The authors have previously shown that planning to cross the arms induces a subjective reversal of spatially defined temporal order judgments that evolves over the course of the planning period. It was unclear, however, whether this effect is modulated by the extent to which the arms would be crossed after movement. The authors examined this issue by having participants plan to move to 4 different targets that would leave the arms in crossed configurations of varying extents. The results demonstrate that even though cutaneous stimuli were applied before the movements, if participants were planning to move into a more crossed configuration, performance on the TOJ task worsened depending on where they were in the planning process. This data suggest the brain uses planning signals to predict sensations from impending movements in a context-dependent manner.     

Bimanual tapping of a syncopated rhythm reveals hemispheric preferences for relative movement frequencies

In bimanual multifrequency tapping, right-handers commonly use the right hand to tap the relatively higher rate and the left hand to tap the relatively lower rate. This could be due to hemispheric specializations for the processing of relative frequencies. An extension of the double-filtering-by-frequency theory to motor control proposes a left hemispheric specialization for the control of relatively high and a right hemispheric specialization for the control of relatively low tapping rates. We investigated timing variability and rhythmic accentuation in right handers tapping mono- and multifrequent bimanual rhythms to test the predictions of the double-filtering-by-frequency theory. Yet, hemispheric specializations for the processing of relative tapping rates could be masked by a left hemispheric dominance for the control of known sequences. Tapping was thus either performed in an overlearned quadruple meter (tap of the slow rhythm on the first auditory beat) or in a syncopated quadruple meter (tap of the slow rhythm on the fourth auditory beat). Independent of syncopation, the right hand outperformed the left hand in timing accuracy for fast tapping. A left hand timing benefit for slow tapping rates as predicted by the double-filtering-by-frequency theory was only found in the syncopated tapping group. This suggests a right hemisphere preference for the control of slow tapping rates when rhythms are not overlearned. Error rates indicate that overlearned rhythms represent hierarchically structured meters that are controlled by a single timer that could potentially reside in the left hemisphere.     

Cortical Networks for Correcting Errors in Sensorimotor Synchronization Depend on the Direction of Asynchrony

Recent work provides clues that different cortical mechanisms may be employed when correcting for errors in sensorimotor synchronization that increase tap-tone asynchrony compared with those that decrease it. The authors tested this hypothesis by recording 64-channel electroencephalography while participants synchronized with an auditory metronome. We systematically introduced positive and negative phase-shift perturbations that were either liminal (10%) and subliminal (3%). We used a distributed source modeling approach to evaluate oscillatory activity and connectivity of discrete cortical sources. Three key findings support our hypothesis. First was a theta band response indicative of error detection and top-down control observed in frontomedial presupplementary motor area (pre-SMA) and anterior cingulate for liminal positive perturbations. Second was an increase in theta band coupling between the SMA and contralateral motor cortex exclusively for positive perturbations suggesting a top-down modulation of motor parameters. Third, when compared with other conditions, liminal positive perturbations result in an increase in postmovement beta rebound within contralateral primary motor cortex. The authors propose that frontomedial motor areas exert a top-down inhibitory influence over the primary motor cortex to effectively lengthen tap intervals in response to lengthening tap-tone asynchronies.     

Motor Skill Learning and the Development of Visual Perception Processes Supporting Action Identification

This study examined physical training and observational training influences on motor learning and the development of visual discrimination processes. Participants were trained on a bimanual task (relative phase of +90°) defined by a visual training stimulus. There were 2 observational contexts: 1) model-only, watch a learning model, and 2) stimulus-only, watch the visual training stimulus. After 2 d of training, the learning models performed the +90° pattern with reduced error in 2 retention tests. Each observer group showed improvement in performance of the +90° pattern, with the stimulus-only group characterized by a more significant improvement. The learning models and observer groups were characterized by an improvement in visually discriminating 2 features of the trained pattern, relative phase and hand-lead. Overall, physical practice (learning models) established a stronger link between the action and visual discrimination processes compared with the observational contexts. The results show that the processes supporting action production and the visual discrimination of actions are modified in ways specific to the trained action following both physical and observational training.     

Emotional Freedom Techniques

Abstract

Callahan (1985) developed a procedure of tapping on acupressure points for treating mental problems. Craig and Fowlie (1995) modified Callahan's procedure to a simplified version called Emotional Freedom Techniques (EFT). EFT is easy to teach and is effective with symptoms of PTSD. This article presents EFT as an adjunct to the Critical Incident Stress Reduction debriefing procedures. The use of EFT in debriefings results in shorter and more thorough sessions. It often reduces the emotional pain of the debriefing. This paper provides complete instructions and safeguards for using EFT when debriefing in disaster situations and with other applications. Included are references for further reading and training.