Visual word recognition insights from MEG and implications for developmental dyslexia

The ability to fluently and, seemingly effortlessly, read words is one of few uniquely special human attributes, but one which has assumed inordinate significance because of the role that this activity has come to have in modern society. A disadvantage in reading ability not only has profound personal impact for the individuals concerned, but in terms of economic and social problems also has a wider negative influence on society at large. According to current government figures in the UK, some 22% of 11 year olds do not reach the minimum standard required in English national curriculum tests. Despite its importance, however, the scientific understanding of the neural basis of reading, and more particularly the visual aspect of visual word recognition, is relatively poorly understood. Thus far, a coherent overarching model, that spans the various conceptual levels, from behaviour through functional description to neuroanatomy, has proven extraordinarily challenging to elucidate. A fuller understanding of the computational processing and neurophysiological basis of how the reading system functions would therefore represent significant progress. As with most complex behaviours, visual word recognition is thought to result from the dynamic interplay between the elements of a distributed cortical and sub-cortical network. To fully understand how visual word recognition is achieved therefore, and how it may fail in developmental dyslexia, we need to identify not only the necessary and sufficient complement of nodes that comprise this network – its functional anatomy - but we also need to understand how information flows through this network with time and indeed how the structure of the network itself may adapt in both the short and long term. In this chapter we take a historical approach to reviewing recent MEG (magnetoencephalography) research which elucidates these temporal dynamics, focusing particularly on events with the first 300ms of a visually presented word, and which we believe should set crucial constraints on models of visual word recognition and reading

During visual word recognition, phonology is accessed within 100 ms and may be mediated by a speech production code: evidence from magnetoencephalography

Debate surrounds the precise cortical location and timing of access to phonological information during visual word recognition. Therefore, using whole-head magnetoencephalography (MEG), we investigated the spatiotemporal pattern of brain responses induced by a masked pseudohomophone priming task. Twenty healthy adults read target words that were preceded by one of three kinds of nonword prime: pseudohomophones (e.g., brein–BRAIN), where four of five letters are shared between prime and target, and the pronunciation is the same; matched orthographic controls (e.g., broin–BRAIN), where the same four of five letters are shared between prime and target but pronunciation differs; and unrelated controls (e.g., lopus–BRAIN), where neither letters nor pronunciation are shared between prime and target. All three priming conditions induced activation in the pars opercularis of the left inferior frontal gyrus (IFGpo) and the left precentral gyrus (PCG) within 100 ms of target word onset. However, for the critical comparison that reveals a processing difference specific to phonology, we found that the induced pseudohomophone priming response was significantly stronger than the orthographic priming response in left IFG/PCG at ∼100 ms. This spatiotemporal concurrence demonstrates early phonological influences during visual word recognition and is consistent with phonological access being mediated by a speech production code

‘To give is better than to receive?’ Couples massage significantly benefits both partners’ wellbeing

This experimental study evaluated the differential effects of ‘giving’ and ‘receiving’ massage on wellbeing in healthy but stressed couples. Forty-two volunteers started the study and of these, 38 (i.e. 19 couples) completed a 3-week massage course. Emotional stress and mental clarity were assessed before and after mutual massage between each pair of adults belonging to a couple at home. While massage benefitted both parties’ wellbeing within a session, critically we found no differences in wellbeing between those ‘giving’ and ‘receiving’ massage. These novel findings suggest that home-based massage may be advocated to couples as a ‘selves-care’, health-promoting behaviour

rTMS evidence for a dissociation in short-term memory for spoken words and nonwords

Differing patterns of verbal short-term memory (STM) impairment have provided unique insights into the relationship between STM and broader language function. Lexicality effects (i.e., better recall for words than nonwords) are larger in patients with phonological deficits following left temporoparietal lesions, and smaller in patients with semantic impairment and anterior temporal damage, supporting linguistic accounts of STM. However, interpretation of these patient dissociations are complicated by (i) non-focal damage and (ii) confounding factors and secondary impairments. This study addressed these issues by examining the impact of inhibitory transcranial magnetic stimulation (TMS) on auditory-verbal STM performance in healthy individuals. We compared the effects of TMS to left anterior supramarginal gyrus (SMG) and left anterior middle temporal gyrus (ATL) on STM for lists of nonwords and random words. SMG stimulation disrupted nonword recall, in a pattern analogous to that observed in patients, compatible with a role for this site in processing speech sounds without support from long-term lexical-semantic representations. Stimulation of ATL, a semantic site, disrupted the recall of words but not nonwords. A visual pattern memory task indicated that these effects of TMS were restricted to the verbal domain. These data provide convergent evidence for the conclusions of neuropsychological studies that support linguistic accounts of verbal STM

Individual differences in verbal short-term memory and reading aloud: Semantic compensation for weak phonological processing across tasks

According to contemporary accounts, linguistic behaviour reflects the interaction of distinct representations supporting word meaning and phonology. However, there is controversy about the extent to which this interaction occurs within task-specific systems, specialised for reading and short-term memory, as opposed to between components that support the full range of linguistic tasks. We examined whether individual differences in the efficiency of phonological processing would relate to the application of lexical-semantic knowledge to support verbal short-term memory, single word reading and repetition. In a sample of 83 participants we related nonword performance in each task (as a marker of phonological capacity in the absence of meaning) to the effects of word imageability (a lexical-semantic variable). We found stronger reliance on lexical-semantic knowledge in participants with weaker phonological processing. This relationship held across tasks, suggesting that lexical-semantic processing can compensate for phonological weakness which would otherwise give rise to poor performance. Our results are consistent with separable yet interacting primary systems for phonology and semantics, with lexical-semantic knowledge supporting pattern completion within the phonological system in a similar way across short-term memory and reading tasks

Context-dependent lexical ambiguity resolution: MEG evidence for the time-course of activity in left inferior frontal gyrus and posterior middle temporal gyrus

An MEG study investigated the role of context in semantic interpretation by examining the comprehension of ambiguous words in contexts leading to different interpretations. We compared high-ambiguity words in minimally different contexts (to bowl, the bowl) to low-ambiguity counterparts (the tray, to flog). Whole brain beamforming revealed the engagement of left inferior frontal gyrus (LIFG) and posterior middle temporal gyrus (LPMTG). Points of interest analyses showed that both these sites showed a stronger response to verb-contexts by 200 ms post-stimulus and displayed overlapping ambiguity effects that were sustained from 300 ms onwards. The effect of context was stronger for high-ambiguity words than for low-ambiguity words at several different time points, including within the first 100 ms post-stimulus. Unlike LIFG, LPMTG also showed stronger responses to verb than noun contexts in low-ambiguity trials. We argue that different functional roles previously attributed to LIFG and LPMTG are in fact played out at different periods during processing

Humans are not fooled by size illusions in attractiveness judgements

Could signallers use size contrast illusions to dishonestly exaggerate their attractiveness to potential mates? Using composite photographs of women from three body mass index (BMI) categories designed to simulate small groups, we show that target women of medium size are judged as thinner when surrounded by larger women than when surrounded by thinner women. However, attractiveness judgements of the same target women were unaffected by this illusory change in BMI, despite small true differences in the BMIs of the target women themselves producing strong effects on attractiveness. Thus, in the context of mate choice decisions, the honesty of female body size as a signal of mate quality appears to have been maintained by the evolution of assessment strategies that are immune to size contrast illusions. Our results suggest that receiver psychology is more flexible than previously assumed, and that illusions are unlikely to drive the evolution of exploitative neighbour choice in human sexual displays. © 2014 The Authors

Optimal asymmetry and other motion parameters that characterise high-quality female dance

Dance is a universal human behaviour that is observed particularly in courtship contexts, and that provides information that could be useful to potential partners. Here, we use a data-driven approach to pinpoint the movements that discriminate female dance quality. Using 3D motion-capture we recorded women whilst they danced to a basic rhythm. Video clips of 39 resultant avatars were rated for dance quality, and those ratings were compared to quantitative measurements of the movement patterns using multi-level models. Three types of movement contributed independently to high-quality female dance: greater hip swing, more asymmetric movements of the thighs, and intermediate levels of asymmetric movements of the arms. Hip swing is a trait that identifies female movement, and the ability to move limbs asymmetrically (i.e. independently of the other) may attest to well-developed motor control, so long as this limb independence does not verge into uncontrolled pathological movement. We also found that the same level of dance quality could be predicted by different combinations of dance features. Our work opens avenues to exploring the functional significance, informational content, and temporal sequencing of the different types of movement in dance

The ageing body: contributing attitudinal factors towards perceptual body size estimates in younger and middle-aged women

Over-estimation of body size, a core feature of eating disorders (EDs), has been well-documented both in young healthy and ED individuals. Yet, evidence that altered body perception might also affect older women is limited. Here, we examined whether attitudinal components of body image (i.e. the feelings an individual has about their body size and shape) might affect perceived actual and ideal body shape self-estimates in midlife, similarly to younger women. Thirty-two younger (mean age, 24.22 years) and 33 middle-aged (mean age, 53.79 years) women took part to a computerized body perception assessment of perceived, actual and ideal aspects of body image. Body mass index (BMI), societal and interpersonal aspects of appearance ideals, measured by means of Sociocultural Attitudes towards Appearance Questionnaire (SATAQ-4), and assessment of body uneasiness and concerns for specific body parts, measured by Body Uneasiness Test (BUT-A/B) scales, were also investigated. Younger and middle-aged women with larger BMI showed greater discrepancy in perceptual distortions from their perceived actual body size. However, middle-aged women with greater body part concerns overestimated their perceived body size, as opposed to younger women who were almost accurate. Unlike middle-aged women, younger women with higher body part concerns desired slimmer ideal body image than their perceived actual. Results suggest that distortions in the perceived actual and ideal body size self-estimates of younger and middle-aged women are best explained by a combination of BMI, body part concerns and the particular age group to which a participant belonged. In the future, a personalized approach for the assessment of women’s perceptions and concerns of specific body areas during lifespan should be adopted

The influence of personal BMI on body size estimations and sensitivity to body size change in anorexia spectrum disorders

In this cross-sectional study, we investigated the influence of personal BMI on body size estimation in 42 women who have symptoms of anorexia (referred to henceforth as anorexia spectrum disorders, ANSD), and 100 healthy controls. Low BMI control participants over-estimate their size and high BMI controls under-estimate, a pattern which is predicted by a perceptual phenomenon called contraction bias. In addition, control participants' sensitivity to size change declines as their BMI increases as predicted by Weber's law. The responses of women with ANSD are very different. Low BMI participants who have ANSD are extremely accurate at estimating body size and are very sensitive to changes in body size in this BMI range. However, as BMI rises in the ANSD participant group, there is a rapid increase in over-estimation concurrent with a rapid decline in sensitivity to size change. We discuss the results in the context of signal detection theory