Neural and Behavioral Outcomes Differ Following Equivalent Bouts of Motor Imagery or Physical Practice.

Despite its reported effectiveness for the acquisition of motor skills, we know little about how motor imagery (MI)-based brain activation and performance evolves when MI (the imagined performance of a motor task) is used to learn a complex motor skill compared to physical practice (PP). The current study examined changes in MI-related brain activity and performance driven by an equivalent bout of MI- or PP-based training. Participants engaged in 5 days of either MI or PP of a dart-throwing task. Brain activity (via fMRI) and performance-related outcomes were obtained using a pre/post/retention design. Relative to PP, MI-based training did not drive robust changes in brain activation and was inferior for realizing improvements in performance: Greater activation in regions critical to refining the motor program was observed in the PP versus MI group posttraining, and relative to those driven via PP, MI led only to marginal improvements in performance. Findings indicate that the modality of practice (i.e., MI vs. PP) used to learn a complex motor skill manifests as differences in both resultant patterns of brain activity and performance. Ultimately, by directly comparing brain activity and behavioral outcomes after equivalent training through MI versus PP, this work provides unique knowledge regarding the neural mechanisms underlying learning through MI.

Transanal total mesorectal excision for rectal cancer: state of the art.

Achieving a high-quality total mesorectal excision (TME) resection specimen is a central tenet of curative rectal cancer management. However, operating at the caudal extremity of the pelvis is inherently challenging and a number of patient- and tumour-related factors may increase the risk of obtaining a poor TME specimen and positive resection margins. Transanal TME (TaTME) is an advanced surgical technique developed to overcome the limitations in pelvic exposure and instrumentation of transabdominal surgery. This up-to-date narrative review describes the evolution of TME surgery, the indications for TaTME, current published outcomes, its limitations and future developments.

Progastrin: a potential predictive marker of liver metastasis in colorectal cancer.

BACKGROUND AND AIMS: Staging of colorectal cancer often fails to discriminate outcomes of patients with morphologically similar tumours that exhibit different clinical behaviours. Data from several studies suggest that the gastrin family of growth factors potentiates colorectal cancer tumourigenesis. The aim of this study was to investigate whether progastrin expression may predict clinical outcome in colorectal cancer. METHODS: Patients with colorectal adenocarcinoma of identical depth of invasion who had not received neoadjuvant therapy were included. The patients either had stage IIa disease with greater than 3-year disease-free survival without adjuvant therapy or stage IV disease with liver metastases on staging CT. Progastrin expression in tumour sections was scored with reference to the intensity and area of immunohistochemical staining. RESULTS: Progastrin expression by stage IV tumours was significantly greater than stage IIa tumours with mean progastrin immunopositivity scores of 2.1 ± 0.2 versus 0.5 ± 0.2, respectively (P < 0.001). CONCLUSIONS: This is the first study to show that progastrin expression may be predictive of aggressive tumour behaviour in patients with colorectal cancer and supports its clinical relevance and potential use as a biomarker.

Indocyanine green fluorescence angiography (ICGFA) during laparoscopic and robotic colorectal surgery- a video vignette.

Anastomotic leaks are a dreaded complication of all colorectal surgery with the main factors contributing to it being tension on the anastomosis, intra-abdominal or systemic sepsis, distal obstruction, inadequate blood supply and improper surgical techniques. The leak rate of left-sided high colorectal resections can have a clinically significant leak rate from as low as 1-5% in high anterior resections to 7.9% in low anastomoses. This article is protected by copyright. All rights reserved.

Sequential actions: effects of upcoming perceptual and motor tasks on current actions.

Reports of spatial interactions between current and upcoming elements in a movement sequence could be due to intentional planning of a "global" action sequence (i.e., strategic effects), or to unintentional motor planning arising from merely paying attention to upcoming target objects (i.e., interference effects). The purpose of this experiment was to determine whether paying attention to an upcoming target object could induce kinematic changes in a current grasping action when there is no strategic advantage associated with such changes. Specifically, participants grasped a rectangular target object in the presence of a second rectangular object that was either ignored, or was the target of a subsequent grasping or perceptual judgment task. Peak grip aperture during the primary grasping action was assessed in relation to the size of the second rectangle. The results revealed an effect of the second rectangle's size only when it was the target of a subsequent perceptual judgment task. This result calls into question the assumption that interactions between current and subsequent elements of an action sequence are necessarily due to strategic movement planning processes and might instead arise from interference arising from merely paying attention to nontarget objects.

Equal-magnitude size-weight illusions experienced within and between object categories.

In the size-weight illusion (SWI), small objects feel heavier than larger objects of the same mass. This effect is typically thought to be a consequence of the lifter's expectation that the large object will outweigh the small object, because objects of the same type typically get heavier as they get larger. Here, we show that this perceptual effect can occur across object category, where there are no strong expectations about the correspondence between size and mass. One group of participants lifted same-colored large and small cubes with the same mass as one another, while another group lifted differently-colored large and small cubes with the same mass as one another. The group who lifted the same-colored cubes experienced a robust SWI and initially lifted the large object with more force than the small object. By contrast, the group who lifted the different-colored objects did so with equal initial forces on the first trial, but experienced just as strong an illusion as those who lifted the same-colored objects. These results demonstrate that color cues can selectively influence the application of fingertip force rates while not impacting at all upon the lifter's perception of object weight, highlighting a stark dissociation in how prior information affects perception and action.

Gastrin mediates resistance to hypoxia-induced cell death in xenografts of the human colorectal cancer cell line LoVo.

AIM: Gastrins act as growth factors for the normal and neoplastic colorectal mucosa. The aim of this study was to determine the role of gastrins in the response of human colorectal cancer (CRC) cells to hypoxia in vitro and in vivo. METHODS: Expression of the gastrin gene in the human CRC cell line LoVo was examined under normoxia and hypoxia by quantitative PCR and by radioimmunoassay. Gastrin expression was knocked down with shRNA, and the effect on cell proliferation was measured by cell counting, on cell apoptosis by annexin V staining, and on cell migration by Boyden chamber assay. The effect of gastrin knockdown on tumourigenesis in mouse xenografts was analysed by measurement of tumour volumes and weights, and by immunohistochemistry. RESULTS: Gastrin gene expression in LoVo cells was stimulated by hypoxia via binding of hypoxia-inducible factor-1α to the gastrin promoter. The viability of gastrin knockdown cells exposed to hypoxia (1% O2) in vitro was diminished because of loss of resistance against hypoxia-induced apoptosis, and the effect was partly reversed by treatment with non-amidated, but not amidated, gastrin. Conditioned medium from control LoVo cells under hypoxia simulated proliferation but not migration, and the effect was blocked by an inhibitor of non-amidated gastrins, but not by an inhibitor of amidated gastrins. In xenografts in mice exposed to hypoxia (10% O2) for 21days, tumour necrosis was significantly increased by knocking down gastrin expression. CONCLUSION: These results provide evidence that non-amidated gastrins are involved in the adaptation of CRCs to hypoxic microenvironments through increasing resistance to apoptosis.

Spatial interactions between consecutive manual responses.

We have shown that the latency to initiate a reaching movement is increased if its direction is the same as a previous movement compared to movements that differ by 90° or 180° (Cowper-Smith and Westwood in Atten Percept Psychophys 75:1914-1922, 2013). An influential study (Taylor and Klein in J Exp Psychol Hum Percept Perform 26:1639-1656, 2000), however, reported the opposite spatial pattern for manual keypress responses: repeated responses on the same side had reduced reaction time compared to responses on opposite sides. In order to determine whether there are fundamental differences in the patterns of spatial interactions between button-pressing responses and reaching movements, we compared both types of manual responses using common methods. Reaching movements and manual keypress responses were performed in separate blocks of trials using consecutive central arrow stimuli that directed participants to respond to left or right targets. Reaction times were greater for manual responses made to the same target as a previous response (M = 390 ms) as compared to the opposite target (M = 365 ms; similarity main effect: p < 0.001) regardless of whether the response was a reaching movement or a keypress response. This finding is broadly consistent with an inhibitory mechanism operating at the level of motor output that discourages movements that achieve the same spatial goal as a recent action.

Pantomime-grasping: the 'return' of haptic feedback supports the absolute specification of object size.

When an individual grasps a physical object, the visuomotor system is able to specify grip aperture via absolute visual information. In contrast, grasping to a location previously occupied by an object (i.e., pantomime-grasping) results in the specification of grip aperture via relative visual information. The basis for the dissociable visual codes is thought to reflect that pantomime-grasping is a perception-based task. It is, however, important to recognize that grasping a physical object and pantomime-grasping differ not only in terms of their visuospatial properties but also with respect to the availability of haptic feedback: Grasping a physical object provides haptic cues derived from touching the object, whereas no such feedback is available in a traditional pantomime-grasping task. As such, we examined whether haptic feedback influences the information supporting a pantomime-grasp performed after a 1000-ms visual delay. Participants completed responses in each of the three tasks: (1) grasping a physical object, (2) traditional pantomime-grasping wherein the to-be-grasped object was removed from the grasping environment and (3) pantomime-grasping wherein the experimenter placed the object between participants' thumb and forefinger once they had completed their response (i.e., pantomime-grasping with haptic feedback). Just-noticeable-difference (JND) scores were computed to determine whether responses adhered to or violated the psychophysical (i.e., relative) principles of Weber's law. JNDs for the traditional pantomime-grasping task adhered to Weber's law, whereas JNDs for grasping a physical object and for pantomime-grasping with haptic feedback violated the law. Thus, we propose that convergent visual and haptic cues support the absolute specification of object size in a pantomime-grasping task. Furthermore, our results highlight the important role of multisensory cue integration in a target-defined grasping task.

Investigating visual attention during scene perception of safe and unsafe occupational performance.

BACKGROUND: Occupational therapists routinely use observation for evaluation, intervention planning, and prediction of a client's occupational performance and/or safety within the environment. Perception of safety contributes to the decision-making process for discharge or placement recommendations. PURPOSE: The purpose of this study was to determine if differences exist in safety ratings and eye movements between occupational therapists and nontrained matched individuals while viewing domain-specific versus non-domain-specific images. METHOD: Ten licensed occupational therapists and 10 age-, gender-, and education level-matched participants completed this eye-tracking study. FINDINGS: For all image exposure durations, occupational therapists had more polarized safety ratings for stroke-related image content but little evidence of differences in eye movements between groups. Eye movement group differences did not emerge in the regions of interest identified by an independent expert panel. IMPLICATIONS: The results point to a complex relationship between decision making and observational behaviour in occupational assessment and highlight the need to look beyond image features.

Observation patterns of dynamic occupational performance.

BACKGROUND: Visual observation is a key component of both formal and informal occupational performance assessment, but it is unknown how therapists gather this visual information. PURPOSE: The purpose of this study was to explore observational behaviour of occupational therapists and non-health care professionals when watching videos of simulated clients post-stroke participating in everyday activity. METHOD: Ten licensed occupational therapists and 10 age-, gender-, and education level-matched participants completed this eye-tracking study. FINDINGS: Contrary to our past work with static image viewing, we found limited evidence of differences in eye movement characteristics between the two groups, although results did support the role of bottom-up information, such as visual motion, as a determinant of looking behaviour. IMPLICATIONS: These results suggest that understanding observational behaviour in therapists can be aided with eye-tracking methodology, but future studies should probe a broad range of factors that might influence observational behaviour and performance, such as assessment goals, knowledge, and therapist experience.

Transparent cap-assisted colonoscopy versus standard adult colonoscopy: a systematic review and meta-analysis.

BACKGROUND: Cap-assisted colonoscopy uses a transparent plastic hood attached to the tip of the colonoscope to flatten the semilunar folds and improve mucosal exposure. Several studies have examined the effect of cap-assisted colonoscopy on polyp detection, but the data are inconsistent. OBJECTIVE: This study aimed to evaluate whether cap-assisted colonoscopy improves the yield of colorectal neoplasia detected compared with standard colonoscopy. DATA SOURCES: A systematic search of the PubMed, MEDLINE, Embase, and Cochrane databases identified 12 studies that met the inclusion criteria for data extraction. STUDY SELECTION: Publications that compared cap-assisted colonoscopy vs standard colonoscopy in adults in a prospective randomized controlled study were selected for review. MAIN OUTCOME MEASURES: The primary outcomes used for meta-analysis were cecal intubation rate, cecal intubation time, and polyp detection rate. The analysis was performed using a fixed-effect model. Outcomes were calculated as odds ratios or standardized mean differences with 95% confidence intervals. The average polyp miss rate determined by tandem colonoscopy was also calculated. RESULTS: The outcomes of 6185 patients were studied. Cap-assisted colonoscopy detected significantly more patients with polyps (OR 1.13; p = 0.030) and had a lower average polyp miss rate (12.2% vs 28.6%) than standard colonoscopy. Cap-assisted colonoscopy had a significantly higher cecal intubation rate than standard colonoscopy (OR 1.36; p = 0.020), whereas the time to cecal intubation (standard mean difference, 0.04 min; p = 0.280) was similar for the 2 colonoscope types. CONCLUSIONS: Cap-assisted colonoscopy is associated with improved detection of colorectal neoplasia and higher cecal intubation rates than standard adult colonoscopy.

Head pre-cooling improves symptoms of heat-sensitive multiple sclerosis patients.

BACKGROUND: Damage to the central nervous system by Multiple Sclerosis (MS) leads to multiple symptoms, including weakness, ambulatory dysfunction, visual disturbances and fatigue. Heat can exacerbate the symptoms of MS whereas cooling can provide symptomatic relief. Since the head and neck areas are particularly sensitive to cold and cooling interventions, we investigated the effects of cooling the head and neck for 60 minutes on the symptoms of MS. METHODS: We used a double blinded, placebo controlled, cross-over study design to evaluate the effects of head and neck cooling on six heat-sensitive, stable, ambulatory females with MS (Extended Disability Status Scale 2.5-6.5). To isolate the effects of perceived versus physiological cooling, a sham cooling condition was incorporated, where subjects perceived the sensation of being cooled without any actual physiological cooling. Participants visited the clinic three times for 60 minutes of true, sham, or no cooling using a custom head and neck cooling hood, followed by evaluation of ambulation, visual acuity, and muscle strength. Rectal and skin temperature, heart rate, and thermal sensation were measured throughout cooling and testing. RESULTS: Both the true and sham cooling elicited significant sensations of thermal cooling, but only the true cooling condition decreased core temperature by 0.37 °C (36.97 ± 0.21 to 36.60 ± 0.23 °C). True cooling improved performance in the six minute walk test and the timed up-and-go test but not visual acuity or hand grip strength. CONCLUSIONS: Head and neck cooling may be an effective tool in increasing ambulatory capacity in individuals with MS and heat sensitivity.

Leveraging the effector independent nature of motor imagery when it is paired with physical practice.

While considered analogous to physical practice, the nature of imagery-based skill acquisition-specifically whether or not both effector independent and dependent encoding occurs through motor imagery-is not well understood. Here, motor imagery-based training was applied prior to or after physical practice-based training to probe the nature of imagery-based skill acquisition. Three groups of participants (N = 38) engaged in 10 days of training of a dart throwing task: 5 days of motor imagery prior to physical practice (MIP-PP), motor imagery following physical practice (PP-MIP), or physical practice only (PP-PP). Performance-related outcomes were assessed throughout. Brain activity was measured at three time points using fMRI (pre/mid/post-training; MIP-PP and PP-MIP groups). In contrast with physical practice, motor imagery led to changes in global versus specific aspects of the movement. Following 10 days of training, performance was greater when motor imagery preceded physical practice, although remained inferior to performance resulting from physical practice alone. Greater activation of regions that support effector dependent encoding was observed mid-, but not post-training for the PP-MIP group. Findings indicate that changes driven by motor imagery reflect effector independent encoding, providing new information regarding how motor imagery may be leveraged for skill acquisition.

Pontomedullary ganglioglioma: a rare tumour in an unusual location.

Gangliogliomas are rare low-grade tumours composed of neoplastic glial and neuronal cell elements. Although they may arise within any part of the neuraxis, involvement of the brainstem is rarely encountered. The distinct nature of gangliogliomas means that they have a comparatively better prognosis than other tumours in this location following subtotal resection. We present the case of an infant with a pontomedullary ganglioglioma and discuss the relevant literature.

Movement related sensory feedback is not necessary for learning to execute a motor skill.

Sensory feedback has traditionally been considered critical for motor learning. While it has been shown that motor learning can occur in the absence of visual or somatosensory feedback, it is thought that at least one must be present. This assumption contrasts with literature demonstrating that motor imagery (MI) - the mental rehearsal of a movement - is capable of driving motor learning even though the lack of actual execution precludes sensory feedback related to movement. However, studies of MI typically employ simple tasks that do not require improvements in motor execution per se, suggesting that MI might improve task performance primarily through perceptual mechanisms. To avoid this limitation, we designed a novel motor task requiring the repeated execution of unfamiliar kinematic trajectories where learning was assessed through changes in the speed-accuracy function (SAF) across five sessions. General task performance was controlled for by assessing performance on randomly generated trajectories. Groups included physical practice (PP; with and without added visual feedback), MI, and perceptual control (PC), the latter of which only observed the trajectories. All groups performed physically on the final session. Upon the final session, the MI group performed better than the PC group, and better than initial session PP performance. These results suggest that motor learning occurred in the MI group despite the lack of sensory feedback related to the movement, and that this learning was not simply the result of perceptual learning. Our results question long-standing assumptions about MI based learning and the necessity of feedback in motor learning generally.

Correction: Mild Traumatic Brain Injury (mTBI) and chronic cognitive impairment: A scoping review.

[This corrects the article DOI: 10.1371/journal.pone.0174847.].

Grasping behavior in schizophrenia suggests selective impairment in the dorsal visual pathway.

This study frames anomalous functional brain organization in schizophrenia (SCZ) within an evolutionary model of brain development, the dual trends theory (DTT). The DTT argues that neural architecture develops along 2 separate pathways: the dorsal archicortical trend and the ventral paleocortical trend. The DTT dovetails with visual system organization, which is also composed of 2 independent pathways: a dorsal stream dedicated to visuomotor action and a ventral stream dedicated to perceptual processing. The present study examined the integrity of these pathways using a size-contrast visual illusion. Prior research has shown that, normally, perceptual estimations of object size are susceptible to visual illusions, whereas goal-directed actions are resistant. The authors hypothesized that, unlike control participants, SCZ patients' actions would be susceptible to the illusion, reflecting dorsal stream dysfunction. Here, 42 SCZ patients and 42 healthy controls grasped and estimated the size of target blocks in control and illusion conditions. During estimation, both groups were equally perturbed by the illusion; however, grasping movements of patients alone were influenced by the illusion. These results suggest disrupted dorsal brain circuitry in SCZ but relatively intact ventral circuitry.