Adaptive Motor Imagery: A Multimodal Study of Immobilization-Induced Brain Plasticity.

The consequences of losing the ability to move a limb are traumatic. One approach that examines the impact of pathological limb nonuse on the brain involves temporary immobilization of a healthy limb. Here, we investigated immobilization-induced plasticity in the motor imagery (MI) circuitry during hand immobilization. We assessed these changes with a multimodal paradigm, using functional magnetic resonance imaging (fMRI) to measure neural activation, magnetoencephalography (MEG) to track neuronal oscillatory dynamics, and transcranial magnetic stimulation (TMS) to assess corticospinal excitability. fMRI results show a significant decrease in neural activation for MI of the constrained hand, localized to sensorimotor areas contralateral to the immobilized hand. MEG results show a significant decrease in beta desynchronization and faster resynchronization in sensorimotor areas contralateral to the immobilized hand. TMS results show a significant increase in resting motor threshold in motor cortex contralateral to the constrained hand, suggesting a decrease in corticospinal excitability in the projections to the constrained hand. These results demonstrate a direct and rapid effect of immobilization on MI processes of the constrained hand, suggesting that limb nonuse may not only affect motor execution, as evidenced by previous studies, but also MI. These findings have important implications for the effectiveness of therapeutic approaches that use MI as a rehabilitation tool to ameliorate the negative effects of limb nonuse.

Effective processing of masked eye gaze requires volitional control.

The purpose of the present study was to establish whether the validity effect produced by masked eye gaze cues should be attributed to strictly reflexive mechanisms or to volitional top-down mechanisms. While we find that masked eye gaze cues are effective in producing a validity effect in a central cueing paradigm, we also find that the efficacy of masked gaze cues is sharply constrained by the experimental context. Specifically, masked gaze cues only produced a validity effect when they appeared in the context of unmasked and predictive gaze cues. Unmasked gaze cues, in contrast, produced reliable validity effects across a range of experimental contexts, including Experiment 4 where 80% of the cues were invalid (counter-predictive). Taken together, these results suggest that the effective processing of masked gaze cues requires volitional control, whereas the processing of unmasked (clearly visible) gaze cues appears to benefit from both reflexive and top-down mechanisms.

Are women with traits of perfectionism more likely to develop perinatal depression? A systematic review and meta-analysis.

Women who present with a maladaptive form of the perfectionism trait may be vulnerable to perinatal depression (PND). The studies examining this association, though, differ in the specific time-points at which PND is measured, the tool/s used to assess PND and/or perfectionism, and the sample of women used; consequently, extant results reflecting this association can be difficult to integrate and interpret. This systematic review and meta-analysis seeks to clarify the association between PND and perfectionism by surveying literature on the relationship. Literature search strategies were developed using medical subject headings (MeSH) and text words related to PND and perfectionism. Nine electronic databases of published and unpublished literature were searched for relevant studies, which were selected for inclusion in this systematic review and meta-analysis if they contained data on female participants aged 18 or over and pregnant or who were within 12 months post-birth; additionally, studies were included if they contained quantitative reporting of depressive symptoms and trait perfectionism symptoms within the perinatal period (between pregnancy and up to 12 months post-birth). Ten publications were selected for inclusion based on independent review against the selection criteria by the authors. Eight of the 10 publications provided substantial correlational data and were analysed using meta-analytic techniques. All studies showed a significant positive relationship between measures of perfectionism and depression at various time points within the perinatal period (3rd trimester to 12-months postpartum), including concurrently in pregnancy, concurrently in postpartum, and longitudinally between pregnancy and postpartum. Interestingly, however, moderation analyses identified that the relationship between perfectionism and PND in the 3rd trimester may emerge only when a perinatal-specific, but not when a general, depression screening tool is used. These analyses also revealed that the strength of the relationship between perfectionism and PND may increase with length of time postpartum. The findings of this systematic review and meta-analysis, thus, suggest that medical professionals should consider perfectionism when formulating PND prevention strategies and assessing for PND using perinatal-specific screening tools.

A novel enhanced intensity-based automatic registration: Augmented reality for visualization and localization cancer tumors.

The purpose of this study is to replace the manual process (selecting the landmarks on mesh and anchor points on the video) by Intensity-based Automatic Registration method to reach registration accuracy and low processing time. The proposed system consists of an Enhanced Intensity-based Automatic Registration (EIbAR) using Modified Zero Normalized Cross Correlation (MZNCC) algorithm. The proposed system was implemented on videos of breast cancer tumors. Results showed that the proposed algorithm-as compared to a reference-improved registration accuracy by an average of 2 mm. In addition, the proposed algorithm-as compared to a reference-reduced the number of pixel matching, thereby reducing processing time on the video by an average of 22 ms/frame. The proposed system can, thus, provide an acceptable accuracy and processing time during scene augmentation of videos, which provides a seamless use of augmented-reality for surgeons in visualizing cancer tumors.

Face matching impairment in developmental prosopagnosia.

Developmental prosopagnosia (DP) is commonly referred to as 'face blindness', a term that implies a perceptual basis to the condition. However, DP presents as a deficit in face recognition and is diagnosed using memory-based tasks. Here, we test face identification ability in six people with DP, who are severely impaired on face memory tasks, using tasks that do not rely on memory. First, we compared DP to control participants on a standardized test of unfamiliar face matching using facial images taken on the same day and under standardized studio conditions (Glasgow Face Matching Test; GFMT). Scores for DP participants did not differ from normative accuracy scores on the GFMT. Second, we tested face matching performance on a test created using images that were sourced from the Internet and so varied substantially due to changes in viewing conditions and in a person's appearance (Local Heroes Test; LHT). DP participants showed significantly poorer matching accuracy on the LHT than control participants, for both unfamiliar and familiar face matching. Interestingly, this deficit is specific to 'match' trials, suggesting that people with DP may have particular difficulty in matching images of the same person that contain natural day-to-day variations in appearance. We discuss these results in the broader context of individual differences in face matching ability.

Do people have insight into their face recognition abilities?

Diagnosis of developmental or congenital prosopagnosia (CP) involves self-report of everyday face recognition difficulties, which are corroborated with poor performance on behavioural tests. This approach requires accurate self-evaluation. We examine the extent to which typical adults have insight into their face recognition abilities across four experiments involving nearly 300 participants. The experiments used five tests of face recognition ability: two that tap into the ability to learn and recognize previously unfamiliar faces [the Cambridge Face Memory Test, CFMT; Duchaine, B., & Nakayama, K. (2006). The Cambridge Face Memory Test: Results for neurologically intact individuals and an investigation of its validity using inverted face stimuli and prosopagnosic participants. Neuropsychologia, 44(4), 576-585. doi:10.1016/j.neuropsychologia.2005.07.001; and a newly devised test based on the CFMT but where the study phases involve watching short movies rather than viewing static faces-the CFMT-Films] and three that tap face matching [Benton Facial Recognition Test, BFRT; Benton, A., Sivan, A., Hamsher, K., Varney, N., & Spreen, O. (1983). Contribution to neuropsychological assessment. New York: Oxford University Press; and two recently devised sequential face matching tests]. Self-reported ability was measured with the 15-item Kennerknecht et al. questionnaire [Kennerknecht, I., Ho, N. Y., & Wong, V. C. (2008). Prevalence of hereditary prosopagnosia (HPA) in Hong Kong Chinese population. American Journal of Medical Genetics Part A, 146A(22), 2863-2870. doi:10.1002/ajmg.a.32552]; two single-item questions assessing face recognition ability; and a new 77-item meta-cognition questionnaire. Overall, we find that adults with typical face recognition abilities have only modest insight into their ability to recognize faces on behavioural tests. In a fifth experiment, we assess self-reported face recognition ability in people with CP and find that some people who expect to perform poorly on behavioural tests of face recognition do indeed perform poorly. However, it is not yet clear whether individuals within this group of poor performers have greater levels of insight (i.e., into their degree of impairment) than those with more typical levels of performance.

Target-object integration, attention distribution, and object orientation interactively modulate object-based selection.

The representational basis of attentional selection can be object-based. Various studies have suggested, however, that object-based selection is less robust than spatial selection across experimental paradigms. We sought to examine the manner by which the following factors might explain this variation: Target-Object Integration (targets 'on' vs. part 'of' an object), Attention Distribution (narrow vs. wide), and Object Orientation (horizontal vs. vertical). In Experiment 1, participants discriminated between two targets presented 'on' an object in one session, or presented as a change 'of' an object in another session. There was no spatial cue-thus, attention was initially focused widely-and the objects were horizontal or vertical. We found evidence of object-based selection only when targets constituted a change 'of' an object. Additionally, object orientation modulated the sign of object-based selection: We observed a same-object advantage for horizontal objects, but a same-object cost for vertical objects. In Experiment 2, an informative cue preceded a single target presented 'on' an object or as a change 'of' an object (thus, attention was initially focused narrowly). Unlike in Experiment 1, we found evidence of object-based selection independent of target-object integration. We again found that the sign of selection was modulated by the objects' orientation. This result may reflect a meridian effect, which emerged due to anisotropies in the cortical representations when attention is oriented endogenously. Experiment 3 revealed that object orientation did not modulate object-based selection when attention was oriented exogenously. Our findings suggest that target-object integration, attention distribution, and object orientation modulate object-based selection, but only in combination.

Direct evidence of cognitive control without perceptual awareness.

A central question within the domain of human cognition is whether or not the ability to replace a current action with a new one (i.e., cognitive control) depends on a conscious appreciation of the environmental change that necessitates the new behavior. Specifically, it is not yet known if non-consciously perceived stimuli can trigger the modification of a currently ongoing action. We show for the first time that individuals are able to use non-consciously perceived information to modify the course and outcome of an ongoing action. Participants were presented with a masked (i.e., subliminal) 'stop' or 'go-on' prime stimulus whilst performing a routine reach-to-touch action. Despite being invisible to participants, the stop primes produced more hesitations mid-flight and more movement reversals than the go-on primes. This new evidence directly establishes that cognitive control (i.e., the ability to modify a currently ongoing action) does not depend on a conscious appreciation of the environmental trigger.

Responding to the direction of the eyes: in search of the masked gaze-cueing effect.

Recent studies have demonstrated that masked gaze cues can produce a cueing effect. Those studies, however, all utilized a localization task and, hence, are ambiguous with respect to whether the previously observed masked gaze-cueing effect reflects the orienting of attention or the preparation of a motor response. The aim of the present study was to investigate this issue by determining whether masked gaze cues can modulate responses in detection and discrimination tasks, both of which isolate spatial attention from response priming. First, we found a gaze-cueing effect for unmasked cues in detection, discrimination, and localization tasks, which suggests that the gaze-cueing effect for visible cues is not task dependent. Second, and in contrast, we found a gaze-cueing effect for masked cues in a localization task, but not in detection or discrimination tasks, which suggests that the gaze-cueing effect for masked cues is task dependent. Therefore, the present study shows that the masked gaze-cueing effect is attributed to response priming, as opposed to the orienting of spatial attention.

Augmenting melodic intonation therapy with non-invasive brain stimulation to treat impaired left-hemisphere function: two case studies.

The purpose of this study was to investigate whether or not the right hemisphere can be engaged using Melodic Intonation Therapy (MIT) and excitatory repetitive transcranial magnetic stimulation (rTMS) to improve language function in people with aphasia. The two participants in this study (GOE and AMC) have chronic non-fluent aphasia. A functional Magnetic Resonance Imaging (fMRI) task was used to localize the right Broca's homolog area in the inferior frontal gyrus for rTMS coil placement. The treatment protocol included an rTMS phase, which consisted of 3 treatment sessions that used an excitatory stimulation method known as intermittent theta burst stimulation, and a sham-rTMS phase, which consisted of 3 treatment sessions that used a sham coil. Each treatment session was followed by 40 min of MIT. A linguistic battery was administered after each session. Our findings show that one participant, GOE, improved in verbal fluency and the repetition of phrases when treated with MIT in combination with TMS. However, AMC showed no evidence of behavioral benefit from this brief treatment trial. Post-treatment neural activity changes were observed for both participants in the left Broca's area and right Broca's homolog. These case studies indicate that a combination of MIT and rTMS applied to the right Broca's homolog has the potential to improve speech and language outcomes for at least some people with post-stroke aphasia.

Non-threatening other-race faces capture visual attention: evidence from a dot-probe task.

Visual attentional biases towards other-race faces have been attributed to the perceived threat value of such faces. It is possible, however, that they reflect the relative visual novelty of other-race faces. Here we demonstrate an attentional bias to other-race faces in the absence of perceived threat. White participants rated female East Asian faces as no more threatening than female own-race faces. Nevertheless, using a new dot-probe paradigm that can distinguish attentional capture and hold effects, we found that these other-race faces selectively captured visual attention. Importantly, this demonstration challenges previous interpretations of attentional biases to other-race faces as threat responses. Future studies will need to determine whether perceived threat increases attentional biases to other-race faces, beyond the levels seen here.