Effect of task complexity on ipsilateral motor response programming to physically presented and imagined stimuli

It is unclear whether task representation generated in imagery simulates performance demands in reacting to stimuli. This study investigated whether perceptual and motor control processes used to react to unpredictable stimuli and initiate an ipsilateral movement were replicated during imagery. Fifty-nine undergraduate students ( Mage = 27.01 years, SD = 8.30) completed 30 simple, two-choice congruent and two-choice incongruent ipsilateral finger–foot movement trials in response to a physically presented or imagined stimulus. The results appear to indicate that participants were reacting to imagined and actual stimuli, as the ipsilateral finger–foot programming rule was maintained and reaction time initially slowed as task difficulty increased. These findings support theoretical similarities between imagery and physical performance of reaction tasks, with imagers generating and reacting to unpredictable stimuli. Slower imagery performance than physical performance on the two-choice incongruent task may indicate that task complexity is limited during imagery. Variation in results between the imagery and physical conditions potentially supports that imagers were able to react to the imagined stimulus. However, exploratory processes used to react to stimuli were not replicated during imagery. The present findings have potentially significant implications for the functional and applied use of imagery for skill acquisition.

How perceptual ambiguity affects response inhibition processes

The ability to inhibit responses is a central requirement for goal-directed behavior but has been dominated by a top-down or cognitive control view. Only recently, the role of bottom-up perceptual factors were focused in research. However, studies usually use clearly distinguishable stimulus categories to trigger response execution or inhibition. In the current study, we present a novel Gabor patch Go/No-go task to induce perceptual ambiguity during response inhibition. To examine the neurophysiological processes in detail, we use EEG recordings and combined temporal EEG signal decomposition methods with source localization analyses. We show that perceptual similarity between Go and No-go trials compromises response inhibition performance. Interestingly, the EEG data show that this is due to a modulation of stimulus-response transition or decision processes, and not purely stimulus-related processes. This was possible by applying a temporal EEG decomposition method. We provide evidence that a prefrontal P2 (pP2) likely reflects decision processes on action execution using stimulus information. These processes were associated with superior and middle prefrontal regions (BA8). When these processes fail, occasions to execute a response become misinterpreted as occasions to inhibit a response. Successful and unsuccessful decisions to inhibit a response under high perceptual ambiguity seem to further depend on how well “what-decisions,” supported by neural mechanisms in BA19, can be processed. However, these what-decisions seem to be closely linked to the specification of the required action. Stimulus processing is closely linked to response programming so that response control is already informed when uncertainty with regard to stimulus identity is detected. NEW & NOTEWORTHY This study introduces a novel Go/No-go paradigm and shows what neurophysiological subprocesses and functional neuroanatomical are involved during inhibitory control when ambiguous stimulus input is provided. The results show that bottom-up perceptual processes are important to consider during top-down controlled response inhibition. Stimulus processing is closely linked to response programming so that response control is already informed when uncertainty with regard to stimulus identity is detected.

Pacemaker programming and device interrogation

This chapter covers all areas of pacemaker programming and choices related to pacing. Methods of choosing rate limits, and related programming features are described for the lower rate interval, the upper rate interval, the atrioventricular interval, and refractory and blanking periods are described in detail. The anatomical and signal changes for each period are defined, and all descriptions are illustrated with example ECGs to show different programme outcomes. Rate response, programming rate response, and mode switching are covered. Automated functions and stored information are described, and algorithms to prevent atrial arrhythmias are explained. Finally, pacemaker-mediated tachycardia is outlined, including detection and methods of terminating the pacemaker-mediated tachycardia (PMT).