Comparison of ultra-low, low and high concentration local anaesthetic for labour epidural analgesia: a systematic review and network meta-analysis.

Lumbar epidural is the gold standard for labour analgesia. Low concentrations of local anaesthetic are recommended. This network meta-analysis investigated whether further reducing the concentration of local anaesthetic can improve maternal and neonatal outcomes without compromising analgesia. We conducted a systematic search of relevant databases for randomised controlled trials comparing high (>0.1%), low (>0.08% to ≤0.1%) or ultra-low (≤0.08%) concentration local anaesthetic (bupivacaine or equivalent) for labour epidural. Outcomes included mode of delivery, duration of labour and maternal/neonatal outcomes. Bayesian network meta-analysis with random-effects modelling was used to calculate odds ratios or weighted mean differences and 95% credible intervals. A total of 32 studies met inclusion criteria (3665 women). The total dose of local anaesthetic received increased as the concentration increased; ultra-low compared with low (weighted mean difference -14.96 mg, 95% credible interval [-28.38 to -1.00]) and low compared with high groups (weighted mean difference -14.99 [-28.79 to -2.04]), though there was no difference in the number of rescue top-ups administered between the groups. Compared with high concentration, ultra-low concentration local anaesthetic was associated with increased likelihood of spontaneous vaginal delivery (OR 1.46 [1.18 to 1.86]), reduced motor block (Bromage score >0; OR 0.32 [0.18 to 0.54]) and reduced duration of second stage of labour (weighted mean difference -13.02 min [-21.54 to -4.77]). Compared with low, ultra-low concentration local anaesthetic had similar estimates for duration of second stage of labour (weighted mean difference -1.92 min [-14.35 to 10.20]); spontaneous vaginal delivery (OR 1.07 [0.75 to 1.56]; assisted vaginal delivery (OR 1.35 [0.75 to 2.26]); caesarean section (OR 0.76 [0.49 to 1.22]); pain (scale 1-100, weighted mean difference -5.44 [-16.75 to 5.93]); and maternal satisfaction. Although a lower risk of an Apgar score < 7 at 1 min (OR 0.43 [0.15 to 0.79]) was reported for ultra-low compared with low concentration, this was not sustained at 5 min (OR 0.12 [0.00 to 2.10]). Ultra-low concentration local anaesthetic for labour epidural achieves similar or better maternal and neonatal outcomes as low and high concentration, but with reduced local anaesthetic consumption.

Inhibitory Control in the Absence of Awareness: Interactions Between Frontal and Motor Cortex Oscillations Mediate Implicitly Learned Responses.

Cognitive control of action is associated with conscious effort and is hypothesised to be reflected by increased frontal theta activity. However, the functional role of these increases in theta power, and how they contribute to cognitive control remains unknown. We conducted an MEG study to test the hypothesis that frontal theta oscillations interact with sensorimotor signals in order to produce controlled behaviour, and that the strength of these interactions will vary with the amount of control required. We measured neuromagnetic activity in 16 healthy adults performing a response inhibition (Go/Switch) task, known from previous work to modulate cognitive control requirements using hidden patterns of Go and Switch cues. Learning was confirmed by reduced reaction times (RT) to patterned compared to random Switch cues. Concurrent measures of pupil diameter revealed changes in subjective cognitive effort with stimulus probability, even in the absence of measurable behavioural differences, revealing instances of covert variations in cognitive effort. Significant theta oscillations were found in five frontal brain regions, with theta power in the right middle frontal and right premotor cortices parametrically increasing with cognitive effort. Similar increases in oscillatory power were also observed in motor cortical gamma, suggesting an interaction. Right middle frontal and right precentral theta activity predicted changes in pupil diameter across all experimental conditions, demonstrating a close relationship between frontal theta increases and cognitive control. Although no theta-gamma cross-frequency coupling was found, long-range theta phase coherence among the five significant sources between bilateral middle frontal, right inferior frontal, and bilateral premotor areas was found, thus providing a mechanism for the relay of cognitive control between frontal and motor areas via theta signalling. Furthermore, this provides the first evidence for the sensitivity of frontal theta oscillations to implicit motor learning and its effects on cognitive load. More generally these results present a possible a mechanism for this frontal theta network to coordinate response preparation, inhibition and execution.

Pupillary responses and reaction times index different cognitive processes in a combined Go/Switch incidental learning task.

In previous studies we have provided evidence that performance in speeded response tasks with infrequent target stimuli reflects both automatic and controlled cognitive processes, based on differences in reaction time (RT) and task-related brain responses (Cheyne et al. 2012, Isabella et al. 2015). Here we test the hypothesis that such shifts in cognitive control may be influenced by changes in cognitive load related to stimulus predictability, and that these changes can be indexed by task-evoked pupillary responses (TEPR). We manipulated stimulus predictability using fixed stimulus sequences that were unknown to the participants in a Go/Switch task (requiring a switch response on 25% of trials) while monitoring TEPR as a measure of cognitive load in 12 healthy adults. Results showed significant improvement in performance (reduced RT, increased efficiency) for repeated sequences compared to occasional deviant sequences (10% probability) indicating that incidental learning of the predictable sequences facilitated performance. All behavioral measures varied between Switch and Go trials (RT, efficiency), however mean TEPR amplitude (mTEPR) and latency to maximum pupil dilation were particularly sensitive to Go/Switch. Results were consistent with the hypothesis that mTEPR indexes cognitive load, whereas TEPR latency indexes time to response selection, independent from response execution. The present study provides evidence that incidental pattern learning during response inhibition tasks may modulate several cognitive processes including cognitive load, effort, response selection and execution, which can in turn have differential effects on measures of performance. In particular, we demonstrate that reaction time may not be indicative of underlying cognitive load.

A Short Boredom Proneness Scale.

It has been evident for some time that the Boredom Proneness Scale (BPS), a commonly used measure of trait boredom, does not constitute a single scale. Factor analytic studies have identified anything from two to seven factors, prompting Vodanovich and colleagues to propose an alternative two factor, short form version Boredom Proneness Scale-Short Form (BPS-SR). The present study further investigates the factor structure and validity of both the BPS and the BPS-SR. The two-factor solution obtained for the BPS-SR appears to be an artifact of item wording of reverse-scored items. These same items may also have contributed to the earlier complexity and inconsistency of results for the full BPS. An eight-item scale of only consistently worded items (i.e., those not requiring reverse scoring) was developed. This new scale demonstrated unidimensionality and the scale score had good internal consistency and construct validity comparable to the original BPS score.

Complementary roles of cortical oscillations in automatic and controlled processing during rapid serial tasks.

Cognitive control may involve adjusting behaviour by inhibiting or altering habitual actions, requiring rapid communication between sensory, cognitive, and motor systems of the brain. Cognitive control may be achieved using top-down processing from frontal areas to inhibit prepared responses, likely mediated through frontal theta (4-8 Hz) oscillations. However there is conflicting evidence for mechanisms of response inhibition, where global and selective inhibition are either considered separate processes, or frontal areas maintain and execute goal-directed actions, including inhibition. In the current study we measured neuromagnetic oscillatory brain activity in twelve adults responding to rapidly presented visual cues. We used two tasks in the same subjects that required inhibition of a habitual "go" response. Presentation of infrequent "target" cues required subjects to completely inhibit responding (go/no-go task) or to perform an alternate response (go/switch task). Source analysis of oscillatory brain activity was compared for correct no-go and switch trials as well as error trials ("go" responses to targets). Frontal theta activity was similar in cortical location, amplitude and time course for correct no-go and switch responses reflecting an equivalent role in both global and selective response inhibition. Error-related frontal theta activity was also observed but was different in source location (errors vs correct, both tasks: p<0.005) and power (go/switch>go/no-go error, correct switch power, p=0.01). We additionally observed sensorimotor high gamma (60-90 Hz) activity accompanying motor responses, which was markedly stronger for correct switch and error responses compared with go responses, and was delayed for errors (p<0.01). These results suggest that gamma signals in the motor cortex may function to integrate inhibitory signals with sensorimotor processing, and may represent a mechanism for the overriding of habitual behaviours, as errors were predicted by a delay in gamma onset. This study supports a role for frontal areas in maintaining and executing goal-directed actions, and demonstrates that frontal theta activity and sensorimotor gamma oscillations have distinct yet complementary functional roles in monitoring and modifying habitual motor plans.

[Ellis van Creveld. Case report]. / Ellis van Creveld: reporte de caso.

INTRODUCTION: Ellis-van Creveld (EVC) (OMIM # 225500) syndrome is a rare skeletal dysplasia disorder transmitted by autosomal recessive inheritance. The diagnosis is made based on phenotypic characteristics such as chondrodysplasia, heart defects and polydactyly. The prognosis depends mainly on the severity of the disease, diagnosis and comprehensive management of the condition. OBJECTIVE: To describe a patient diagnosed with EVC syndrome. CASE REPORT: Newborn diagnosed with EVC syndrome who presented dysmorphic facies, shortened long bones, rhizomelic shortening, small hands, brachydactyly, single transverse palmar crease, postaxial polydactyly in the upper limbs, bilateral preaxial polysyndactyly in lower limbs and hypoplastic nails, complex heart defects and narrow thorax. The evolution was unfavorable; the patient died 8 weeks after birth from complications due to heart defects. CONCLUSIONS: EVC syndrome is rare and unknown; therefore, it is important to spread its characteristics within the pediatric community, emphasizing that it affects multiple organ systems and requires a multidisciplinary approach to treat individually each patient, to provide genetic and reproductive counseling to couples and to give information regarding child development expectations.

In manually-assisted search, perception supervises rather than directs action.

During manually-assisted search, where participants must actively manipulate search items, it has been reported that participants will often select and move the target of search itself without recognizing it (Solman et al., 2012a). In two experiments we explore the hypothesis that this error results from a naturally-arising strategy that decouples perception and action during search, enabling motor interactions with items to outpace the speed of perceptual analysis. In Experiment 1, we report that the error is prevalent for both mouse and touch-screen interaction modes, and is uninfluenced by speeding or slowing instructions--ruling out these task-specific details as causes of the error. In Experiment 2 we manipulate motor speed, and show that reducing the speed of individual movements during search leads to a reduction in error rates. These findings support the conclusion that the error results from incoordination between motor and perceptual processes, with motor processes outpacing perceptual abilities.

Changing perspective: zooming in and out during visual search.

Laboratory studies of visual search are generally conducted in contexts with a static observer vantage point, constrained by a fixation cross or a headrest. In contrast, in many naturalistic search settings, observers freely adjust their vantage point by physically moving through space. In two experiments, we evaluate behavior during free vantage point (FVP) search, using observer-controlled zooming to simulate movement toward or away from search objects. We focus on scope fluctuations--repeated reversals in the direction of zooming during search. We found increased fluctuation when search items were sparse (Experiment 1) or of mixed size (Experiment 2). We propose that during FVP search, observers attempt to maximize the number of simultaneously discriminable items. Scope fluctuations emerge when maximizing does not enable simultaneous access to all search items, or when observers become disoriented in the search environment, necessitating repeated switches to a broad scope to reorient.

Anomalous bodily-self experiences among recreational ketamine users.

INTRODUCTION: Out-of-body experiences present a unique paradigm to investigate cognitive and neural mechanisms of bodily-self processes and their disorders. Previous work on out-of-body experiences associated with sleep paralysis supported a model in which illusory movement experiences reflect disrupted bodily-self integration generating anomalous vestibular and motor sensations. Further disintegration and progression of the experience may then give rise to out-of-body feelings, which in turn may instigate out-of-body autoscopy. METHODS: The current study assesses the disintegration model through analyses of out-of-body experiences reports from an online survey of individuals reporting recreational ketamine use (n=128) and cross-validation in a sample of nonketamine polydrug users (n=64). Path analyses using intensity and frequency measures of anomalous experiences assess the fit of seven competing models. RESULTS: The disintegration model (illusory movement → out-of-body feelings → out-of-body autoscopy) emerged as the best fitting model overall and results support full mediation of the relation between illusory movement experiences and out-of-body autoscopy by out-of-body feelings. Moreover, lifetime measures of ketamine use predicted the frequency of illusory movement experiences. CONCLUSIONS: The results corroborate this structural model of out-of-body phenomena and encourage a framework for future studies into aetiological mechanisms of out-of-body experiences to include neurochemical systems.

Found and missed: failing to recognize a search target despite moving it.

We present results from five search experiments using a novel 'unpacking' paradigm in which participants use a mouse to sort through random heaps of distractors to locate the target. We report that during this task participants often fail to recognize the target despite moving it, and despite having looked at the item. Additionally, the missed target item appears to have been processed as evidenced by post-error slowing of individual moves within a trial. The rate of this 'unpacking error' was minimally affected by set size and dual task manipulations, but was strongly influenced by perceptual difficulty and perceptual load. We suggest that the error occurs because of a dissociation between perception for action and perception for identification, providing further evidence that these processes may operate relatively independently even in naturalistic contexts, and even in settings like search where they should be expected to act in close coordination.

Memory load affects visual search processes without influencing search efficiency.

Participants' eye-movements were monitored while they searched for a target among a varying number of distractors either with or without a concurrent memory load. Consistent with previous findings, adding a memory load slowed response times without affecting search slopes; a finding normally taken to imply that memory load affects pre- and/or post-search processes but not the search process itself. However, when overall response times were decomposed using eye-movement data into pre-search (e.g., initial encoding), search, and post-search (e.g., response selection) phases, analysis revealed that adding a memory load affected all phases, including the search phase. In addition, we report that fixations selected under load were more likely to be distant from search items, and more likely to be close to previously inspected locations. Thus, memory load affects the search process without affecting search slopes. These results challenge standard interpretations of search slopes and main effects in visual search.

Ketamine as a primary predictor of out-of-body experiences associated with multiple substance use.

Investigation of "out-of-body experiences" (OBEs) has implications for understanding both normal bodily-self integration and its vulnerabilities. Beyond reported associations between OBEs and specific brain regions, however, there have been few investigations of neurochemical systems relevant to OBEs. Ketamine, a drug used recreationally to achieve dissociative experiences, provides a real-world paradigm for investigating neurochemical effects. We investigate the strength of the association of OBEs and ketamine use relative to other common drugs of abuse. Self-report data (N=192) from an online survey indicate that both lifetime frequency of ketamine use and OBEs during ketamine intoxication were more strongly related to the frequency of OBEs and related phenomena than other drugs. Moreover, the apparent effects of other drugs could largely be explained by associated ketamine use. The present results, consistent with the role of NMDA receptors in OBEs, should encourage future studies of the role of neurochemical systems in OBEs.

Age trends for failures of sustained attention.

Recent research has revealed an age-related reduction in errors in a sustained attention task, suggesting that sustained attention abilities improve with age. Such results seem paradoxical in light of the well-documented age-related declines in cognitive performance. In the present study, performance on the sustained attention to response task (SART) was assessed in a supplemented archival sample of 638 individuals between 14 and 77 years old. SART errors and response speed appeared to decline in a linear fashion as a function of age throughout the age span studied. In contrast, other measures of sustained attention (reaction time coefficient of variation), anticipation, and omissions) showed a decrease early in life and then remained unchanged for the rest of the life span. Thus, sustained attention shows improvements with maturation in early adulthood but then does not change with aging in older adults. On the other hand, aging across the entire life span leads to a more strategic (i.e., slower) response style that reduces the overt and critical consequences (i.e., SART errors) of momentary task disengagement.

Failures of sustained attention in life, lab, and brain: ecological validity of the SART.

The Sustained Attention to Response Task (SART) is a widely used tool in cognitive neuroscience increasingly employed to identify brain regions associated with failures of sustained attention. An important claim of the SART is that it is significantly related to real-world problems of sustained attention such as those experienced by TBI and ADHD patients. This claim is largely based on its association with the Cognitive Failures Questionnaire (CFQ), but recently concerns have been expressed about the reliability of the SART-CFQ association. Based on a review of the literature, meta-analysis of prior research, and analysis of original data, we conclude that, across studies sampling diverse populations and contexts, the SART is reliably associated with the CFQ. The CFQ-SART relation also holds for patients with TBI. We note, however, conceptual limitations of using the CFQ, which was designed as a measure of general cognitive failures, to validate the SART, which was specifically designed to assess sustained attention. To remedy this limitation, we report on associations between the SART and a specific Attention-Related Cognitive Errors Scale (ARCES) and a Mindful Awareness of Attention Scale-Lapses Only (MAAS-LO).

Anatomy of an error: a bidirectional state model of task engagement/disengagement and attention-related errors.

We present arguments and evidence for a three-state attentional model of task engagement/disengagement. The model postulates three states of mind-wandering: occurrent task inattention, generic task inattention, and response disengagement. We hypothesize that all three states are both causes and consequences of task performance outcomes and apply across a variety of experimental and real-world tasks. We apply this model to the analysis of a widely used GO/NOGO task, the Sustained Attention to Response Task (SART). We identify three performance characteristics of the SART that map onto the three states of the model: RT variability, anticipations, and omissions. Predictions based on the model are tested, and largely corroborated, via regression and lag-sequential analyses of both successful and unsuccessful withholding on NOGO trials as well as self-reported mind-wandering and everyday cognitive errors. The results revealed theoretically consistent temporal associations among the state indicators and between these and SART errors as well as with self-report measures. Lag analysis was consistent with the hypotheses that temporal transitions among states are often extremely abrupt and that the association between mind-wandering and performance is bidirectional. The bidirectional effects suggest that errors constitute important occasions for reactive mind-wandering. The model also enables concrete phenomenological, behavioral, and physiological predictions for future research.

The body unbound: vestibular-motor hallucinations and out-of-body experiences.

Among the varied hallucinations associated with sleep paralysis (SP), out-of-body experiences (OBEs) and vestibular-motor (V-M) sensations represent a distinct factor. Recent studies of direct stimulation of vestibular cortex report a virtually identical set of bodily-self hallucinations. Both programs of research agree on numerous details of OBEs and V-M experiences and suggest similar hypotheses concerning their association. In the present study, self-report data from two on-line surveys of SP-related experiences were employed to assess hypotheses concerning the causal structure of relations among V-M experiences and OBEs during SP episodes. The results complement neurophysiological evidence and are consistent with the hypothesis that OBEs represent a breakdown in the normal binding of bodily-self sensations and suggest that out-of-body feelings (OBFs) are consequences of anomalous V-M experiences and precursors to a particular form of autoscopic experience, out-of-body autoscopy (OBA). An additional finding was that vestibular and motor experiences make relatively independent contributions to OBE variance. Although OBEs are superficially consistent with universal dualistic and supernatural intuitions about the nature of the soul and its relation to the body, recent research increasingly offers plausible alternative naturalistic explanations of the relevant phenomenology.

Everyday attention lapses and memory failures: the affective consequences of mindlessness.

We examined the affective consequences of everyday attention lapses and memory failures. Significant associations were found between self-report measures of attention lapses (MAAS-LO), attention-related cognitive errors (ARCES), and memory failures (MFS), on the one hand, and boredom (BPS) and depression (BDI-II), on the other. Regression analyses confirmed previous findings that the ARCES partially mediates the relation between the MAAS-LO and MFS. Further regression analyses also indicated that the association between the ARCES and BPS was entirely accounted for by the MAAS-LO and MFS, as was that between the ARCES and BDI-II. Structural modeling revealed the associations to be optimally explained by the MAAS-LO and MFS influencing the BPS and BDI-II, contrary to current conceptions of attention and memory problems as consequences of affective dysfunction. A lack of conscious awareness of one's actions, signaled by the propensity to experience brief lapses of attention and related memory failures, is thus seen as having significant consequences in terms of long-term affective well-being.

Paranoid delusions and threatening hallucinations: a prospective study of sleep paralysis experiences.

Previously we reported a three-factor structure for hallucinations accompanying sleep paralysis (SP). These earlier analyses were, however, based on retrospective accounts. In a prospective study, 383 individuals reported individual episodes online providing further evidence for the three-factor structure as well as clearer conceptually meaningful relations among factors than retrospective studies. In addition, reports of individual episodes permitted a more fine-grained analysis of the internal structure of factors to assess predictions based on the hypothesis that a sensed or felt presence (FP) is a core experience affecting other SP hallucinations. Results were generally consistent with this hypothesis. In particular, associations among, and temporal stability of, sensory hallucinations were largely explained by their common association with FP. The findings are consistent with REM initiation of a threat activated vigilance system with pervasive effects on the SP experience and suggest a potential model for the thematic organization of nightmares and dreams more generally.