A longitudinal analysis of factors associated with post traumatic growth after acquired brain injury

ABSTRACTPost-Traumatic Growth (PTG) is a form of positive psychological change that occurs for some individuals following traumatic experiences. High levels of PTG have been reported among survivors of acquired brain injury (ABI). Yet it remains unclear why some survivors of ABI develop PTG and others do not. The present study investigated early and late factors that are associated with long-term PTG in people with moderate to severe ABIs. Participants (n = 32, Mage = 50.59, SD = 12.28) completed self-report outcome measures at two time-points seven years apart (one-year and eight-years post-ABI). Outcome measures assessed emotional distress, coping, quality of life and ongoing symptoms of brain injury, as well as PTG at the later timepoint. Multiple regression analyses indicated that one-year post-ABI, fewer symptoms of depression, more symptoms of anxiety, and use of adaptive coping strategies accounted for a significant amount of variance in later PTG. At eight years post-ABI, fewer symptoms of depression, fewer ongoing symptoms of brain injury, better psychological quality of life and use of adaptive coping strategies explained a substantial amount of variance in PTG. For individuals with ABIs, PTG may be promoted by implementing long-term neuropsychological support which aims to facilitate use of adaptive coping strategies, supports psychological wellbeing and allows individuals to find meaning post-ABI.

Actions are characterized by 'canonical moments' in a sequence of movements

Understanding what others are doing is an essential aspect of social cognition that depends on our ability to quickly recognize and categorize their actions. To effectively study action recognition we need to understand how actions are bounded, where they start and where they end. Here we borrow a conceptual approach - the notion of 'canonicality' - introduced by Palmer and colleagues in their study of object recognition and apply it to the study of action recognition. Using a set of 50 video clips sourced from stock photography sites, we show that many everyday actions - transitive and intransitive, social and non-social, communicative - are characterized by 'canonical moments' in a sequence of movements that are agreed by participants to 'best represent' a named action, as indicated in a forced choice (Exp 1, n = 142) and a free choice (Exp 2, n = 125) paradigm. In Exp 3 (n = 102) we confirm that canonical moments from action sequences are more readily named as depicting specific actions and, mirroring research in object recognition, that such canonical moments are privileged in memory (Exp 4, n = 95). We suggest that 'canonical moments', being those that convey maximal information about human actions, are integral to the representation of human action.1.

Quantitative TMT-based proteomics revealing host, dietary and microbial proteins in bovine faeces including barley serpin Z4, a prominent component in the head of beer

There has been little information about the proteome of bovine faeces or about the contribution to the faecal proteome of proteins from the host, the feed or the intestinal microbiome. Here, the bovine faecal proteome and the origin of its component proteins was assessed, while also determining the effect of treating barley, the major carbohydrate in the feed, with either ammonia (ATB) or sodium propionate (PTB) preservative. Healthy continental crossbreed steers were allocated to two groups and fed on either of the barley-based diets. Five faecal samples from each group were collected on Day 81 of the trial and analysed by quantitative proteomics using nLC-ESI-MS/MS after tandem mass tag labelling. In total, 281 bovine proteins, 199 barley proteins, 176 bacterial proteins and 190 archaeal proteins were identified in the faeces. Mucosal pentraxin, albumin and digestive enzymes were among bovine proteins identified. Serpin Z4 a protease inhibitor was the most abundant barley protein identified which is also found in barley-based beer, while numerous microbial proteins were identified, many originating bacteria from Clostridium, while Methanobrevibacter was the dominant archaeal genus. Thirty-nine proteins were differentially abundant between groups, the majority being more abundant in the PTB group compared to the ATB group. SIGNIFICANCE: Proteomic examination of faeces is becoming a valuable means to assess the health of the gastro-intestinal tract in several species, but knowledge on the proteins present in bovine faeces is limited. This investigation aimed to characterise the proteome of bovine faecal extracts in order to evaluate the potential for investigations of the proteome as a means to assess the health, disease and welfare of cattle in the future. The investigation was able to identify proteins in bovine faeces that had been (i) produced by the individual cattle, (ii) present in the barley-based feed eaten by the cattle or (iii) produced by bacteria and other microbes in the rumen or intestines. Bovine proteins identified included mucosal pentraxin, serum albumin and a variety of digestive enzymes. Barley proteins found in the faeces included serpin Z4, a protease inhibitor that is also found in beer having survived the brewing process. Bacterial and archaeal proteins in the faecal extracts were related to several pathways related to the metabolism of carbohydrates. The recognition of the range of proteins that can be identified in bovine faeces raises the possibility that non-invasive sample collection of this material could provide a novel diagnostic approach to cattle health and welfare.

National audit of non-melanoma skin cancer excisions performed by plastic surgery in the UK

A national, multi-centre audit of non-melanoma skin cancer excisions by plastic surgery.

Mental rotation of hands and objects in ageing and Parkinson's disease: differentiating motor imagery and visuospatial ability

Motor imagery supports motor learning and performance and has the potential to be a useful strategy for neurorehabilitation. However, motor imagery ability may be impacted by ageing and neurodegeneration, which could limit its therapeutic effectiveness. Motor imagery can be assessed implicitly using a hand laterality task (HLT), whereby laterality judgements are slower for stimuli corresponding to physically more difficult postures, as indicated by a “biomechanical constraint” effect. Performance is also found to differ between back and palm views of the hand, which may differentially recruit visual and sensorimotor processes. Older adults and individuals with Parkinson’s disease (PD) have shown altered performance on the HLT; however, the effects of both ageing and PD on laterality judgements for the different hand views (back and palm) have not been directly examined. The present study compared healthy younger, healthy older, and PD groups on the HLT, an object-based mental rotation task, and an explicit motor imagery measure. The older and PD groups were slower than the younger group on the HLT, particularly when judging laterality from the back view, and exhibited increased biomechanical constraint effects for the palm. While response times were generally similar between older and PD groups, the PD group showed reduced accuracy for the back view. Letter rotation was slower and less accurate only in the PD group, while explicit motor imagery ratings did not differ significantly between groups. These results suggest that motor imagery may be slowed but relatively preserved in both typical ageing and neurodegeneration, while a PD-specific impairment in visuospatial processing may influence task performance. The findings have implications for the use of motor imagery in rehabilitation protocols.

Feelings first? Sex differences in affective and cognitive processes in emotion recognition

The recognition of emotional expressions is important for social understanding and interaction, but findings on the relationship between emotion recognition, empathy, and theory of mind, as well as sex differences in these relationships, have been inconsistent. This may reflect the relative involvement of affective and cognitive processes at different stages of emotion recognition and in different experimental paradigms. In this study, images of faces were morphed from neutral to full expression of five basic emotions (anger, disgust, fear, happiness, and sadness), which participants were asked to identify as quickly and accurately as possible. Accuracy and response times from healthy males (n = 46) and females (n = 43) were analysed in relation to self-reported empathy (Empathy Quotient; EQ) and mentalising/theory of mind (Reading the Mind in the Eyes Test). Females were faster and more accurate than males in recognising dynamic emotions. Linear mixed-effects modelling showed that response times were inversely related to the emotional empathy subscale of the EQ, but this was accounted for by a female advantage on both measures. Accuracy was unrelated to EQ scores but was predicted independently by sex and Eyes Test scores. These findings suggest that rapid processing of dynamic emotional expressions is strongly influenced by sex, which may reflect the greater involvement of affective processes at earlier stages of emotion recognition.

Holistic processing of faces and words predicts reading accuracy and speed in dyslexic readers

We compared the performance of dyslexic and typical readers on two perceptual tasks, the Vanderbilt Holistic Face Processing Task and the Holistic Word Processing Task. Both yield a metric of holistic processing that captures the extent to which participants automatically attend to information that is spatially nearby but irrelevant to the task at hand. Our results show, for the first time, that holistic processing of faces is comparable in dyslexic and typical readers but that dyslexic readers show greater holistic processing of words. Remarkably, we show that these metrics predict the performance of dyslexic readers on a standardized reading task, with more holistic processing in both tasks associated with higher accuracy and speed. In contrast, a more holistic style on the words task predicts less accurate reading of both words and pseudowords for typical readers. We discuss how these findings may guide our conceptualization of the visual deficit in dyslexia.

Self-reported outcomes and patterns of service engagement after an acquired brain injury: a long-term follow-up study

PRIMARY OBJECTIVE

To describe the clinical characteristics, self-reported outcomes in domains relating to activities of daily living and patterns of service engagement in the survivors of a moderate-to-severe acquired brain injury over seven years.

RESEARCH DESIGN

A longitudinal research design was used.

METHODS AND PROCEDURES

Thirty-two individuals who sustained a moderate-to-severe acquired brain injury completed a Sociodemographic and Support Questionnaire at one (t1) and seven years (t2) after completing a publicly funded inpatient neurorehabilitation program.

MAIN OUTCOMES AND RESULTS

There were minimal changes in independent living, mobility, ability to maintain key relationships and in return to work in the interval between t1 and t2. Sixty-nine percent of participants engaged with two or more allied health professional services and 75% engaged with support services in the community over the seven years.

CONCLUSIONS

There were minimal additional gains in outcomes relating to activities of daily-living and there was a high level of service need in the first decade postinjury. Young and middle-aged individuals who sustain an ABI may continue to live in the community for decades with some level of disability and may require ongoing access to services.

Efficacy, Use, and Acceptability of a Web-Based Self-management Intervention Designed to Maximize Sexual Well-being in Men Living With Prostate Cancer: Single-Arm Experimental Study

BACKGROUND

Sexual dysfunction is a frequent side effect associated with different prostate cancer treatment approaches. It can have a substantial impact on men and their partners and is associated with increased psychological morbidity. Despite this, sexual concerns are often not adequately addressed in routine practice. Evidence-based web-based interventions have the potential to provide ongoing information and sexual well-being support throughout all stages of care.

OBJECTIVE

The aim of this study is to examine the efficacy of a web-based self-management intervention designed to maximize sexual well-being in men living with prostate cancer and explore user perspectives on usability and acceptability.

METHODS

We used a single-arm study design, and participants were provided with access to the 5-step intervention for a period of 3 months. The intervention content was tailored based on responses to brief screening questions on treatment type, relationship status, and sexual orientation. Efficacy was assessed by using two-tailed, paired sample t tests for comparing the mean differences between pre- and postintervention measurements for exploring the participants' self-reported knowledge and understanding, sexual satisfaction, and comfort in discussing sexual issues. Usability and acceptability were determined based on the program use data and a postintervention survey for exploring perceived usefulness.

RESULTS

A total of 109 participants were recruited for this study. Significant postintervention improvements at follow-up were observed in the total scores (out of 20) from the survey (mean 12.23/20 points, SD 2.46 vs mean 13.62/20, SD 2.31; t₈₈=9.570; P=.001) as well as in individual item scores on the extent to which the participants agreed that they had sufficient information to manage the impact that prostate cancer had on their sex life (mean 2.31/4 points, SD 0.86 vs mean 2.57/4, SD 0.85; t₈₈=3.660; P=.001) and had the potential to have a satisfying sex life following treatment (mean 2.38/4 points, SD 0.79 vs mean 3.17/4, SD 0.78; t₈₈=7.643; P=.001). The median number of intervention sessions was 3 (range 1-11), and intervention sessions had a median duration of 22 minutes (range 8-77). Acceptable usability scores were reported, with the highest result observed for the question on the extent to which the intervention provided relevant information.

CONCLUSIONS

This study provides evidence on the efficacy of a tailored web-based intervention for maximizing sexual well-being in men living with prostate cancer. The results indicate that the intervention may improve one's self-perceived knowledge and understanding of how to manage sexual issues and increase self-efficacy or the belief that a satisfactory sex life could be achieved following treatment. The findings will be used to refine the intervention content before testing as part of a larger longitudinal study for examining its effectiveness.

The Tablet-Based, Engagement, Assessment, Support, and Sign-Posting (EASSi) Tool for Facilitating and Structuring Sexual Well-Being Conversations in Routine Prostate Cancer Care: Mixed-Methods Study

Background

Long-term side-effects associated with different prostate cancer treatment approaches are common. Sexual challenges are the most frequently occurring issues and can result in increased psychological morbidity. It is recognized that barriers to communication can make initiating discussions around sexual concerns in routine practice difficult. Health care professionals need to routinely initiate conversations, effectively engage with patients, and assess needs in order to provide essential support. One proposed method that could support health care professionals to do this involves the use of prompts or structured frameworks to guide conversations.

Objective

This study aimed to assess feasibility, acceptability, and satisfaction with the tablet-based Engagement, Assessment, Support, and Sign-posting (EASSi) tool designed to facilitate and structure sexual well-being discussions in routine prostate cancer care.

Methods

Health care professionals (n=8) used the EASSi tool during 89 posttreatment appointments. Quantitative data were recorded based on program usage and surveys completed by health care professionals and patients. Qualitative data exploring perceptions on use of the tool were gathered using semistructured interviews with all health care professionals (n=8) and a sample of patients (n=10).

Results

Surveys were completed by health care professionals immediately following each appointment (n=89, 100%). Postal surveys were returned by 59 patients (66%). Health care professionals and patients reported that the tool helped facilitate discussions (81/89, 91% and 50/59, 85%, respectively) and that information provided was relevant (82/89, 92% and 50/59, 85%, respectively). The mean conversation duration was 6.01 minutes (SD 2.91). Qualitative synthesis identified the tool’s ability to initiate and structure discussions, improve the “depth” of conversations, and normalize sexual concerns.

Conclusions

The EASSi tool was appropriate and acceptable for use in practice and provided a flexible approach to facilitate routine brief conversations and deliver essential sexual well-being support. Further work will be conducted to evaluate the effectiveness of using the tablet-based tool in prostate cancer care settings.

Development of a conceptual framework to improve sexual wellbeing communication in routine prostate cancer care

OBJECTIVE

To systematically develop a framework to improve sexual wellbeing communication in routine prostate cancer care.

METHODS

The Theoretical Domains Framework was used to guide a multi-phase process used to identify components of the framework based on evidence reviews, semi-structured interviews and stakeholder workshops. 'Think-aloud' testing was used to explore usability, potential barriers and other factors relevant to implementation.

RESULTS

A conceptual communication framework consisting of 'Engagement' (E), 'Assessment' (A), information and 'Support' (S) and 'Sign-posting' (Si) sections was developed. The framework emphasises routine engagement to normalise sexual concerns, brief, non-sensitive assessment, personalised advice based on treatment type and relationship status, and a mechanism for referral to additional support or self-management resources in the form of a patient and partner handout. Usability testing identified strategies to promote implementation.

CONCLUSIONS

The proposed framework is appropriate for use in routine practice and appears to be acceptable to patients, partners and healthcare professionals. Its use may help address gaps in sexual wellbeing support for men and partners living with prostate cancer. Further work will be conducted evaluating an online engagement tool, modelled on the framework.

PRACTICE IMPLICATIONS

The EASSi framework can facilitate and structure sexual wellbeing conversations and ensure fundamental but individualised support is provided routinely in prostate cancer care.

Healthcare professional perceived barriers and facilitators to discussing sexual wellbeing with patients after diagnosis of chronic illness: A mixed-methods evidence synthesis

OBJECTIVES

To explore healthcare professional perceived barriers and facilitators to discussing sexual health and wellbeing with patients after diagnosis of chronic illness.

METHODS

Five databases were searched and included data were synthesised using a meta-ethnographic approach. Confidence in findings was assessed using the GRADE-CERQual framework. Searches, extraction and quality assessment procedures were conducted independently by at least two authors.

RESULTS

Concepts extracted from 30 included studies were used to develop a conceptual framework based on five overarching themes. These were [1] individual and societal attitudes to sex and sexual wellbeing [2], patient specific factors [3], organizational and professional factors [4], strategies to overcome barriers in practice and [5] perceived training needs. Healthcare professionals acknowledged the importance of discussing and providing support for sexual wellbeing needs, but recognized it is not routinely provided.

CONCLUSIONS

While patient specific factors and organizational issues such as lack of time were frequently identified as barriers, intra-personal and social perceptions appear to have the strongest influence on healthcare professional perspectives.

PRACTICE IMPLICATIONS

Brief education and tools to support healthcare professionals to have effective conversations with patients are required. These should address social barriers, normalise sexual issues, and support healthcare professionals to initiate discussions around sexual concerns.

Pointing perception is precise

The spontaneity and ease with which we point understates the gesture's significance to understanding cognition. Onset of pointing in infancy predicts early word acquisition and signals a capacity for shared intentionality. Yet, notwithstanding its importance, there is little research on the perception of pointing and its referents. Here we show that perceptual acuity for discerning where another person is pointing is remarkably accurate. Thresholds, as low as 0.5° of visual angle across an interpersonal distance of ∼2 m, are modulated by the referent's location in space and the hand used to point and remain constant when the pointer's eyes are occluded from view and when 'embodiment' cues are enhanced or minimized. Pointing with the index finger not only directs attention toward a general region of space but the morphology of arm, hand and finger can be used to discern the location of the pointer's attention with precision.

Holistic word processing in dyslexia

People with dyslexia have difficulty learning to read and many lack fluent word recognition as adults. In a novel task that borrows elements of the ‘word superiority’ and ‘word inversion’ paradigms, we investigate whether holistic word recognition is impaired in dyslexia. In Experiment 1 students with dyslexia and controls judged the similarity of pairs of 6- and 7-letter words or pairs of words whose letters had been partially jumbled. The stimuli were presented in both upright and inverted form with orthographic regularity and orientation randomized from trial to trial. While both groups showed sensitivity to orthographic regularity, both word inversion and letter jumbling were more detrimental to skilled than dyslexic readers supporting the idea that the latter may read in a more analytic fashion. Experiment 2 employed the same task but using shorter, 4- and 5-letter words and a design where orthographic regularity and stimuli orientation was held constant within experimental blocks to encourage the use of either holistic or analytic processing. While there was no difference in reaction time between the dyslexic and control groups for inverted stimuli, the students with dyslexia were significantly slower than controls for upright stimuli. These findings suggest that holistic word recognition, which is largely based on the detection of orthographic regularity, is impaired in dyslexia.

Point Me in the Right Direction: Same and Cross Category Visual Aftereffects to Directional Cues

Of the many hand gestures that we use in communication pointing is one of the most common and powerful in its role as a visual referent that directs joint attention. While numerous studies have examined the developmental trajectory of pointing production and comprehension, very little consideration has been given to adult visual perception of hand pointing gestures. Across two studies, we use a visual adaptation paradigm to explore the mechanisms underlying the perception of proto-declarative hand pointing. Twenty eight participants judged whether 3D modeled hands pointed, in depth, at or to the left or right of a target (test angles of 0°, 0.75° and 1.5° left and right) before and after adapting to either hands or arrows which pointed 10° to the right or left of the target. After adaptation, the perception of the pointing direction of the test hands shifted with respect to the adapted direction, revealing separate mechanisms for coding right and leftward pointing directions. While there were subtle yet significant differences in the strength of adaptation to hands and arrows, both cues gave rise to a similar pattern of aftereffects. The considerable cross category adaptation found when arrows were used as adapting stimuli and the asymmetry in aftereffects to left and right hands suggests that the adaptation aftereffects are likely driven by simple orientation cues, inherent in the morphological structure of the hand, and not dependent on the biological status of the hand pointing cue. This finding provides evidence in support of a common neural mechanism that processes these directional social cues, a mechanism that may be blind to the biological status of the stimulus category.

Heads First: Visual Aftereffects Reveal Hierarchical Integration of Cues to Social Attention

Determining where another person is attending is an important skill for social interaction that relies on various visual cues, including the turning direction of the head and body. This study reports a novel high-level visual aftereffect that addresses the important question of how these sources of information are combined in gauging social attention. We show that adapting to images of heads turned 25° to the right or left produces a perceptual bias in judging the turning direction of subsequently presented bodies. In contrast, little to no change in the judgment of head orientation occurs after adapting to extremely oriented bodies. The unidirectional nature of the aftereffect suggests that cues from the human body signaling social attention are combined in a hierarchical fashion and is consistent with evidence from single-cell recording studies in nonhuman primates showing that information about head orientation can override information about body posture when both are visible.

Inversion effects in the perception of the moving human form: a comparison of adolescents with autism spectrum disorder and typically developing adolescents

The "body inversion effect" refers to superior recognition of upright than inverted images of the human body and indicates typical configural processing. Previous research by Reed et al. using static images of the human body shows that people with autism fail to demonstrate this effect. Using a novel task in which adults, adolescents with autism, and typically developing adolescents judged whether walking stick figures-created from biological motion recordings and shown at seven orientations between 0° and 180°-were normal or distorted, this study shows clear effects of stimulus inversion. Reaction times and "inverse efficiency" increased with orientation for normal but not distorted walkers, and sensitivity declined with rotation from upright for all groups. Notably, the effect of stimulus inversion was equally detrimental to both groups of adolescents suggesting intact configural processing of the body in motion in autism spectrum disorder.

Holistic processing of faces as measured by the Thatcher illusion is intact in autism spectrum disorders

Impaired face perception in autism spectrum disorders is thought to reflect a perceptual style characterized by componential rather than configural processing of faces. This study investigated face processing in adolescents with autism spectrum disorders using the Thatcher illusion, a perceptual phenomenon exhibiting 'inversion effects' that characterize typical face processing. While previous studies used a limited range of face orientations, we measured perception of normality/grotesqueness of faces at seven orientations ranging from upright to inverted to allow for a detailed comparison of both reaction time and error by orientation profiles. We found that, like their typically developing peers, adolescents with autism spectrum disorders show strong inversion effects whereby reaction times were longer and error rates greater at inverted when compared to upright orientations. Additionally, the adolescents with autism spectrum disorders, like their peers in the typically developing group, show a marked nonlinearity in the error by orientation profile. Error is roughly constant out to 90° and then increases steeply, indicating a sudden shift from configural to local processing that reflects experience with faces in their typical orientations. These findings agree with recent reports that face perception is qualitatively similar in autistic and neurotypical groups.

Inversion effects in the perception of the moving human form: A comparison of adolescents with autism spectrum disorder and typically developing adolescents

The “body inversion effect” refers to superior recognition of upright than inverted images of the human body and indicates typical configural processing. Previous research by Reed et al. using static images of the human body shows that people with autism fail to demonstrate this effect. Using a novel task in which adults, adolescents with autism, and typically developing adolescents judged whether walking stick figures—created from biological motion recordings and shown at seven orientations between 0° and 180°—were normal or distorted, this study shows clear effects of stimulus inversion. Reaction times and “inverse efficiency” increased with orientation for normal but not distorted walkers, and sensitivity declined with rotation from upright for all groups. Notably, the effect of stimulus inversion was equally detrimental to both groups of adolescents suggesting intact configural processing of the body in motion in autism spectrum disorder.

‘Is Seeing Perceiving?’ Exploring issues concerning access to public transport for people with sight loss

This research examined the needs and experiences of people with sight loss regarding access to bus and rail services in a large urban area in Ireland. A broad qualitative approach was used, so as to investigate people’s lived experiences both as passengers and as providers of public transport. Participants included 13 people with differing levels of sight loss and the Access Officers from two public transport organisations in the area. From this research, it is apparent that travel in the area by people with sight loss has improved since the introduction of key pieces of legislation. Awareness of sight loss and assistance given by staff members was the most prominent area of improvement reported by the participants. However, there appeared to be an inequality in access among people with sight loss, in that people with low vision appear to benefit more from access services than people who are totally blind. Research also showed that although technologies, including audible announcements, to assist passengers with more severe sight loss exist, they are not all available in Ireland yet or are not always effective. People’s own experience of sight loss and travelling as a person with reduced vision seems also to contribute to how accessible a transport service is and further research in this area is recommended.

Shared or separate mechanisms for self-face and other-face processing? Evidence from adaptation

Evidence that self-face recognition is dissociable from general face recognition has important implications both for models of social cognition and for our understanding of face recognition. In two studies, we examine how adaptation affects the perception of personally familiar faces, and we use a visual adaptation paradigm to investigate whether the neural mechanisms underlying the recognition of one’s own and other faces are shared or separate. In Study 1 we show that the representation of personally familiar faces is rapidly updated by visual experience with unfamiliar faces, so that the perception of one’s own face and a friend’s face is altered by a brief period of adaptation to distorted unfamiliar faces. In Study 2, participants adapted to images of their own and a friend’s face distorted in opposite directions; the contingent aftereffects we observe are indicative of separate neural populations, but we suggest that these reflect coding of facial identity rather than of the categories “self” and “other.”

My hand or yours? Markedly different sensitivity to egocentric and allocentric views in the hand laterality task

In the hand laterality task participants judge the handedness of visually presented stimuli – images of hands shown in a variety of postures and views - and indicate whether they perceive a right or left hand. The task engages kinaesthetic and sensorimotor processes and is considered a standard example of motor imagery. However, in this study we find that while motor imagery holds across egocentric views of the stimuli (where the hands are likely to be one's own), it does not appear to hold across allocentric views (where the hands are likely to be another person's). First, we find that psychophysical sensitivity, d', is clearly demarcated between egocentric and allocentric views, being high for the former and low for the latter. Secondly, using mixed effects methods to analyse the chronometric data, we find high positive correlation between response times across egocentric views, suggesting a common use of motor imagery across these views. Correlations are, however, considerably lower between egocentric and allocentric views, suggesting a switch from motor imagery across these perspectives. We relate these findings to research showing that the extrastriate body area discriminates egocentric (‘self’) and allocentric (‘other’) views of the human body and of body parts, including hands.

Perception of 'best likeness' to highly familiar faces of self and friend

We investigated the idea that our memory for familiar faces involves an accurate representation of their unique spatial configuration and, further, whether this configuration may be caricatured in memory. In separate experimental blocks, thirty-five Irish participants were presented with a series of photographic images of their own face and of the face of a close friend, and were asked to choose the image which looked most like themselves or their friend. Both sets of images included an original full-face colour photograph, and photographic distortions ranging from a highly caricatured (+100%) to a highly anti-caricatured (-100%) version of the original, generated with reference to newly created average male and female Irish faces. Contrary to suggestions that we hold a slightly caricatured version of a familiar face in memory, the mean 'best-likeness' image, calculated across both self and friend trials, was an anti-caricature of -13.88% which was significantly different from 0 (t69 = -5.34, p < 0.0001). The difference in the mean 'best-likeness' image chosen for self (-12.06%) and friend (-15.7%) was not significant (t34 = 0.715, p = 0.48). These results are discussed with reference to our ability to discriminate facial shape, together with the possibility that we idealise the attractiveness of faces of those close to us.

Self-face recognition is characterized by “bilateral gain” and by faster, more accurate performance which persists when faces are inverted

We examine interhemispheric cooperation in the recognition of personally known faces whose long-term familiarity ensures frequent co-activation of face-sensitive areas in the right and left brain. Images of self, friend, and stranger faces were presented for 150 ms in upright and inverted orientations both unilaterally, in the right or left visual field, and bilaterally. Consistent with previous research, we find a bilateral advantage for familiar but not for unfamiliar faces, and we demonstrate that this gain occurs for inverted as well as upright faces. We show that friend faces are recognized more quickly than unfamiliar faces in upright but not in inverted orientations, suggesting that configural processing underlies this particular advantage. Novel to this study is the finding that people are faster and more accurate at recognizing their own face over both stranger and friend faces and that these advantages occur for both upright and inverted faces. These findings are consistent with evidence for a bilateral representation of self-faces.

Rapid perceptual switching of a reversible biological figure

Certain visual stimuli can give rise to contradictory perceptions. In this paper we examine the temporal dynamics of perceptual reversals experienced with biological motion, comparing these dynamics to those observed with other ambiguous structure from motion (SFM) stimuli. In our first experiment, naïve observers monitored perceptual alternations with an ambiguous rotating walker, a figure that randomly alternates between walking in clockwise (CW) and counter-clockwise (CCW) directions. While the number of reported reversals varied between observers, the observed dynamics (distribution of dominance durations, CW/CCW proportions) were comparable to those experienced with an ambiguous kinetic depth cylinder. In a second experiment, we compared reversal profiles with rotating and standard point-light walkers (i.e. non-rotating). Over multiple test repetitions, three out of four observers experienced consistently shorter mean percept durations with the rotating walker, suggesting that the added rotational component may speed up reversal rates with biomotion. For both stimuli, the drift in alternation rate across trial and across repetition was minimal. In our final experiment, we investigated whether reversals with the rotating walker and a non-biological object with similar global dimensions (rotating cuboid) occur at random phases of the rotation cycle. We found evidence that some observers experience peaks in the distribution of response locations that are relatively stable across sessions. Using control data, we discuss the role of eye movements in the development of these reversal patterns, and the related role of exogenous stimulus characteristics. In summary, we have demonstrated that the temporal dynamics of reversal with biological motion are similar to other forms of ambiguous SFM. We conclude that perceptual switching with biological motion is a robust bistable phenomenon.

Perceptual asymmetries are preserved in memory for highly familiar faces of self and friend

We investigated the effect of familiarity on people's perception of facial likeness by asking participants to choose which of two mirror-symmetric chimeric images (made from the left or right half of a photograph of a face) looked more like an original image. In separate trials the participants made this judgment for their own face and for the face of a close friend; half of them matched to a true image of the original and half matched to a mirror image of the original. In the case of matching to a friend's face presented in the familiar orientation, over 80% of participants chose the left-left composite to be a better likeness to the original, whereas only 62% showed the same left-side bias when matching to a mirror image. The difference is significant, and the result contrasts markedly with a second experiment where participants who were unfamiliar with the faces showed comparable left-side biases when matching to true or mirror reversed images. The result suggests that perceptual asymmetries are retained in our long-term memory for highly familiar faces. While matching to images of self also showed an effect of familiarity, the data in this condition show less evidence of perceptual asymmetry and are discussed in relation to recent research on the representation of one's own face.

My left brain and me: a dissociation in the perception of self and others

We investigated hemispheric asymmetries in face processing using a task in which participants judged the likeness of chimeric faces to their own face and to the face of a close friend based on their memory for those faces. When asked to choose which of two mirror-symmetric images (one made from the left half and one from the right half of a photograph of their face) looked more like themselves as remembered, participants showed a significant bias for the composite corresponding to the half face that lies in their right visual field when they look at themselves in the mirror. They showed the opposite bias when asked to make the same choice for images of a close friend, that is, they showed a significant bias for the composite corresponding to the half face that lies in their left visual field when they look at their friend. This result shows that in the case of these highly familiar faces--self and friend--the perceptual asymmetry is preserved in the memory representation. Assuming that people remember their own face as a mirror-image, the data also suggest a dissociation in face processing such that the left brain is dominant for the recognition of self and the right brain is dominant for the recognition of others.

A double-blind, placebo-controlled crossover study investigating the effect of porcine secretin in children with autism

A recent patient series reported the incidental findings of improved social and language skills in 3 children with autistic spectrum disorders after the administration of secretin, a peptide hormone. However, a subsequent study did not find evidence for a drug effect. Parents are seeking treatment with secretin despite the absence of empirical investigations demonstrating amelioration in autism symptomology. In order to more precisely measure the effects of secretin, this study investigated the effect of a single intravenous dose of porcine secretin on 12 autistic children through a randomized, double-blind, placebo-controlled, crossover study. Children were assessed on objective language and on social, neuropsychological, and gastrointestinal measures to evaluate drug effects. The study was conducted over a 16-week trial. The results indicated that significant differences were not observed on the majority of the dependent variables. Statistically significant differences were observed on measures of positive affect and activity level following secretin infusion. In general, the autistic children did not demonstrate the improvements described in the initial retrospective report.

Local contrast in natural images: normalisation and coding efficiency

The visual system employs a gain control mechanism in the cortical coding of contrast whereby the response of each cell is normalised by the integrated activity of neighbouring cells. While restricted in space, the normalisation pool is broadly tuned for spatial frequency and orientation, so that a cell's response is adapted by stimuli which fall outside its 'classical' receptive field. Various functions have been attributed to divisive gain control: in this paper we consider whether this output nonlinearity serves to increase the information carrying capacity of the neural code. 46 natural scenes were analysed with the use of oriented, frequency-tuned filters whose bandwidths were chosen to match those of mammalian striate cortical cells. The images were logarithmically transformed so that the filters responded to a luminance ratio or contrast. In the first study, the response of each filter was calibrated relative to its response to a grating stimulus, and local image contrast was expressed in terms of the familiar Michelson metric. We found that the distribution of contrasts in natural images is highly kurtotic, peaking at low values and having a long exponential tail. There is considerable variability in local contrast, both within and between images. In the second study we compared the distribution of response activity before and after implementing contrast normalisation, and noted two major changes. Response variability, both within and between scenes, is reduced by normalisation, and the entropy of the response distribution is increased after normalisation, indicating a more efficient transfer of information.

The physical maps for sequencing human chromosomes 1, 6, 9, 10, 13, 20 and X

We constructed maps for eight chromosomes (1, 6, 9, 10, 13, 20, X and (previously) 22), representing one-third of the genome, by building landmark maps, isolating bacterial clones and assembling contigs. By this approach, we could establish the long-range organization of the maps early in the project, and all contig extension, gap closure and problem-solving was simplified by containment within local regions. The maps currently represent more than 94% of the euchromatic (gene-containing) regions of these chromosomes in 176 contigs, and contain 96% of the chromosome-specific markers in the human gene map. By measuring the remaining gaps, we can assess chromosome length and coverage in sequenced clones.

Spatial scale interactions and image statistics

In natural scenes and other broadband images, spatial variations in luminance occur at a range of scales or frequencies. It is generally agreed that the visual image is initially represented by the activity of separate frequency-tuned channels, and this notion is supported by physiological evidence for a stage of multi-resolution filtering in early visual processing. The question whether these channels can be accessed as independent sources of information in the normal course of events is a more contentious one. In the psychophysical study of both motion and spatial vision, there are examples of tasks in which fine-scale structure dominates perception or performance and obscures information at coarser scales. It is argued here that one important factor determining the relative salience of information from different spatial scales in broadband images is the distribution of response activity across spatial channels. The special case of natural scenes that have characteristic 'scale-invariant' power spectra in which image contrast is roughly constant in equal octave frequency bands is considered. A review is presented of evidence which suggests that the sensitivity of frequency-tuned filters in the visual system is matched to this image statistic, so that, on average, different channels respond with equal activity to natural scenes. Under these conditions, the visual system does appear to have independent access to information at different spatial scales and spatial scale interactions are not apparent.

Is human motion detection subserved by a single or multiple channel mechanism?

Two recent versions of a single channel model of motion perception have had impressive success in explaining direction discrimination by human observers for spatially filtered noise images in two-flash apparent motion. It has been argued that the dramatic breakdown in motion perception which occurs when one image in the two-flash sequence is low-pass filtered can be explained only by a single channel model. We show that neither version of the single channel model which has been proposed can explain performance for noise images chosen to provide comparable stimulation in the spatial channels known to subserve human vision. A multi-channel model of motion perception has little difficulty in explaining these results.

Visual sensitivity, blur and the sources of variability in the amplitude spectra of natural scenes

A number of researchers have suggested that in order to understand the response properties of cells in the visual pathway, we must consider the statistical structure of the natural environment. In this paper, we focus on one aspect of that structure, namely, the correlational structure which is described by the amplitude or power spectra of natural scenes. We propose that the principle insight one gains from considering the image spectra is in understanding the relative sensitivity of cells tuned to different spatial frequencies. This study employs a model in which the peak sensitivity is constant as a function of frequency with linear bandwith increasing (i.e., approximately constant in octaves). In such a model, the "response magnitude" (i.e., vector length) of cells increases as a function of their optimal (or central) spatial frequency out to about 20 cyc/deg. The result is a code in which the response to natural scenes, whose amplitude spectra typically fall as 1/f, is roughly constant out to 20 cyc/deg. An important consideration in evaluating this model of sensitivity is the fact that natural scenes show considerable variability in their amplitude spectra, with individual scenes showing falloffs which are often steeper or shallower than 1/f. Using a new measure of image structure (the "rectified contrast spectrum" or "RCS") on a set of calibrated natural images, it is shown that a large part of the variability in the spectra is due to differences in the sparseness of local structure at different scales. That is, an image which is "in focus" will have structure (e.g., edges) which has roughly the same magnitude across scale. That is, the loss of high frequency energy in some images is due to the reduction of the number of regions that contain structure rather than the amplitude of that structure. An "in focus" image will have structure (e.g., edges) across scale that have roughly equal magnitude but may vary in the area covered by structure. The slope of the RCS was found to provide a reasonable prediction of physical blur across a variety of scenes in spite of the variability in their amplitude spectra. It was also found to produce a good prediction of perceived blur as judged by human subjects.

Independent coding across spatial scales in moving fractal images

We compared observers' ability to discriminate the direction of apparent motion using images which varied in their spatial characteristic; white or flat spectrum noise, and 1/f noise which has an amplitude spectrum characteristic of natural scenes. The upper spatial limit for discrimination (dmax) was measured using a two-flash random dot kinematogram (RDK), which consisted either of a pair of bandpass filtered images or of a bandpass filtered image and its broadband counterpart. Six bandpass central frequencies were used, ranging from 0.25 to 5.66 cyc/deg. Subjects could perform the direction discrimination task for all six central frequencies in both the bandpass-bandpass and bandpass-broadband sequences for the 1/f images, and dmax values were found to be approximately equal in these two conditions at all spatial scales. However, for the white noise images, direction discrimination was not possible at the lowest central frequencies in the bandpass-broadband task. These data show that information from a wide range of spatial scales is equally salient to the human motion system in images whose amplitude spectra fall as 1/f. However, for white noise images, information at the higher spatial frequencies is more salient and dominates performance in the direction discrimination task. These results are consistent with a model in which spatial frequency filters in the input lines of motion detectors have octave constant spatial frequency bandwidths and equal peak sensitivity. In line with a number of recent studies, this suggests that the spatial properties of motion sensitive cells are matched to the statistical properties of natural scenes.

What's constant in contrast constancy? The effects of scaling on the perceived contrast of bandpass patterns

"Contrast constancy" refers to the ability to perceive objects as maintaining a constant contrast independent of size or distance. When tested with high contrast sinusoidal gratings, contrast constancy has been shown to hold for a wide range of spatial frequencies, suggesting that sensitivity is constant across the spectrum at suprathreshold. In this study, we show that contrast constancy also holds for relatively broadband patterns. We describe how the frequency spectra of such functions change as the patterns scale in size. In particular, we emphasize how these changes in the spectra depend on whether the functions are localized (coherent phase) or spatially distributed (incoherent phase). In Fourier terms, the scaling properties depend on the phase spectra of the patterns. Contrast constancy is shown to hold for both localized Gabor patches (coherent phase spectra) and bandpass noise patterns (incoherent phase spectra). Constancy holds over a wide range of suprathreshold contrasts; in fact, matching is quite accurate as soon as the pattern is suprathreshold. These results are explained with a model in which mechanism bandwidths increase with frequency (constant in octaves) and peak spectral sensitivity is equal across frequency out to around 16 c/deg. In the case of the Gabor stimuli, perceived contrast is assumed to be mediated by a mechanism centered on the patch. For the bandpass noise, contrast is determined by the average response of units distributed across the stimulus. This model can account for the matching data without assuming that the contrast-response gain of the underlying channels changes with spatial frequency. Neither does the model assume "response pooling". In addition to explaining the experimental results, the model also predicts that perceived contrast will be approximately constant across scale for scenes whose spectra fall as 1/f, as is typical of natural scenes.

Molecular basis of essential fructosuria: molecular cloning and mutational analysis of human ketohexokinase (fructokinase)

Essential fructosuria is one of the oldest known inborn errors of metabolism. It is a benign condition which is believed to result from deficiency of hepatic fructokinase (ketohexokinase, KHK, E.C.2.7.1.3). This enzyme catalyses the first step of metabolism of dietary fructose, conversion of fructose to fructose-1-phosphate. Despite the early recognition of this disorder, the primary structure of human KHK and the molecular basis of essential fructosuria have not been previously defined. In this report, the isolation and sequencing of full-length cDNA clones encoding human ketohexokinase are described. Alternative mRNA species and alternative KHK isozymes are produced by alternative polyadenylation and splicing of the KHK gene. The KHK proteins show a high level of sequence conservation relative to rat KHK. Direct evidence that mutation of the KHK structural gene is the cause of essential fructosuria was also obtained. In a well-characterized family, in which three of eight siblings have fructosuria, all affected individuals are compound heterozygotes for two mutations Gly40Arg and Ala43Thr. Both mutations result from G-->A transitions, and each alters the same conserved region of the KHK protein. Neither mutation was seen in a sample of 52 unrelated control individuals. An additional conservative amino acid change (Val49IIe) was present on the KHK allele bearing Ala43Thr.