Proceedings of the National Academy of Sciences. Auditory Processing Disorder International Research. Adults with dyslexia are impaired in categorizing speech and nonspeech sounds on the basis of temporal cues. Author Affiliations Edited* by Michael M. Merzenich, University of California, San Francisco, CA, and approved April 30, 2010 (received for review November 9, 2009) Abstract Developmental dyslexia is characterized by severe reading and spelling difficulties that are persistent and resistant to the usual didactic measures and remedial efforts.
It is well established that a major cause of these problems lies in poorly specified representations of speech sounds. Speech contains a number of acoustic cues that are used to discriminate speech sounds belonging to different phonetic categories. Although previous speech perception studies predominantly indicate that individuals with dyslexia are less categorical than normal readers in the way that they perceive phonetic contrasts, especially stop consonants (7–28; but see 6, 29–32 for contra-evidence), these studies are inconclusive as to whether these problems are exclusive to speech.
Fig. 1. Table 1. Results Fig. 2. Table 2. Discussion Methods Stimuli. Assistive listening devices drive neuroplasticity in children with dyslexia. Author Affiliations Edited by Thomas D. Albright, The Salk Institute for Biological Studies, La Jolla, CA, and approved August 3, 2012 (received for review April 23, 2012) Abstract Children with dyslexia often exhibit increased variability in sensory and cognitive aspects of hearing relative to typically developing peers.
Children with dyslexia, reading impairment not caused by deficits in ability or opportunity (1), often have difficulties with orienting and maintaining attention (2, 3). Auditory perception and neurophysiology can be altered with auditory training (17⇓⇓⇓⇓⇓–23). What are the biological mechanisms by which classroom FM system use improves auditory attention and phonological awareness in children with dyslexia? Results FM System Use Benefits Reading and Related Skills. We assessed reading ability, phonological awareness, and auditory brainstem function in response to speech in 38 normal hearing children with dyslexia (ages 8–14 y, 16 girls). Fig. 1. Fig. 2. Discussion Footnotes. Amplitude envelope onsets and developmental dyslexia: A new hypothesis. Author Affiliations Communicated by James L. McClelland, Carnegie Mellon University, Pittsburgh, PA (received for review January 25, 2002) Abstract A core difficulty in developmental dyslexia is the accurate specification and neural representation of speech.
Footnotes ↵† To whom reprint requests should be addressed at: Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom. Abbreviations AM, amplitude modulation RAN, rapid automatized naming PSTM, phonological short-term memory RFD, rapid-frequency discrimination TOJ, temporal order judgement CA, chronological age RL, reading level WISC, Wechsler Intelligence Scale for Children P center, perceptual center Received January 25, 2002.
Attention-driven auditory cortex short-term plasticity helps segregate relevant sounds from noise. Author Affiliations Edited* by Robert Desimone, Massachusetts Institute of Technology, and approved January 22, 2011 (received for review November 1, 2010) Abstract How can we concentrate on relevant sounds in noisy environments?
A “gain model” suggests that auditory attention simply amplifies relevant and suppresses irrelevant afferent inputs. However, it is unclear whether this suffices when attended and ignored features overlap to stimulate the same neuronal receptive fields. A “tuning model” suggests that, in addition to gain, attention modulates feature selectivity of auditory neurons. Humans have a remarkable capacity for auditory selective attention in noisy environments. These two classic theories have been recently complemented by results supporting a more detailed “tuning model” of auditory attention (14–18).
Fig. 1. Task design and hypotheses. Results Behavioral Data. Dynamic MEG/EEG/fMRI Estimates. Fig. 2. Event-related MEG responses. Fig. 3. Fig. 4. Fig. 5. fMRI Results. Discussion. Auditory plasticity and speech motor learning. Author Affiliations Edited by Michael M. Merzenich, University of California, San Francisco, CA, and approved September 24, 2009 (received for review June 28, 2009) Abstract Is plasticity in sensory and motor systems linked? Footnotes 1To whom correspondence should be addressed. A structural–functional basis for dyslexia in the cortex of Chinese readers. Author Affiliations Communicated by Robert Desimone, Massachusetts Institute of Technology, Cambridge, MA, February 25, 2008 (received for review January 1, 2008) Abstract Developmental dyslexia is a neurobiologically based disorder that affects ≈5–17% of school children and is characterized by a severe impairment in reading skill acquisition.
For readers of alphabetic (e.g., English) languages, recent neuroimaging studies have demonstrated that dyslexia is associated with weak reading-related activity in left temporoparietal and occipitotemporal regions, and this activity difference may reflect reductions in gray matter volume in these areas. Here, we find different structural and functional abnormalities in dyslexic readers of Chinese, a nonalphabetic language. Developmental dyslexia is characterized by unexpectedly low reading ability in people who have adequate intelligence, typical schooling, and sufficient sociocultural opportunities (1–10). Table 1. Results Fig. 1. Fig. 2. Table 2. Beat synchronization predicts neural speech encoding and reading readiness in preschoolers. Author Affiliations Edited* by Michael Merzenich, Brain Plasticity Institute, San Francisco, CA, and approved August 21, 2014 (received for review April 3, 2014) Significance Sensitivity to fine timing cues in speech is thought to play a key role in language learning, facilitating the development of phonological processing.
In fact, a link between beat synchronization, which requires fine auditory–motor synchrony, and language skills has been found in school-aged children, as well as adults. Here, we show this relationship between beat entrainment and language metrics in preschoolers and use beat synchronization ability to predict the precision of neural encoding of speech syllables in these emergent readers. Abstract Temporal cues are important for discerning word boundaries and syllable segments in speech; their perception facilitates language acquisition and development. Results Drumming Consistency. Fig. 1. Language Metrics. Speech Syllable Envelope Encoding. Fig. 2. Discussion Participants. Brain sensitivity to print emerges when children learn letter–speech sound correspondences. Author Affiliations Edited by Michael Posner, University of Oregon, Eugene, OR, and approved March 5, 2010 (received for review April 21, 2009) A correction has been published Abstract The acquisition of reading skills is a major landmark process in a human's cognitive development.
On the neural level, a new functional network develops during this time, as children typically learn to associate the well-known sounds of their spoken language with unfamiliar characters in alphabetic languages and finally access the meaning of written words, allowing for later reading. Learning to read starts with the establishment of grapheme–phoneme correspondences between letters and speech sounds in alphabetic languages such as German or English. Left occipito-temporal cortex regions, referred to as the “visual word-form system” (VWFS) (2), are often engaged in print processing. Table 1. Characteristics of training groups Fig. 1. Results Behavior. Training intensity.
Letter Knowledge and Reading. fMRI. Table 2. Components of verbal working memory: Evidence from neuroimaging. Abstract We review research on the neural bases of verbal working memory, focusing on human neuroimaging studies. We first consider experiments that indicate that verbal working memory is composed of multiple components. One component involves the subvocal rehearsal of phonological information and is neurally implemented by left-hemisphere speech areas, including Broca’s area, the premotor area, and the supplementary motor area. Other components of verbal working memory may be devoted to pure storage and to executive processing of the contents of memory.
These studies rest on a subtraction logic, in which two tasks are imaged, differing only in that one task presumably has an extra process, and the difference image is taken to reflect that process. We then review studies that show that the previous results can be obtained with experimental methods other than subtraction. Research on human WM has been carried out at both behavioral and biological levels. Figure 1 Figure 2 Figure 3 Figure 4. Dysfunction of the auditory thalamus in developmental dyslexia.
Author Affiliations Edited by Michael Merzenich, W. M. Keck Center for Integrative Neuroscience, San Francisco, CA, and approved July 16, 2012 (received for review December 5, 2011) Abstract Developmental dyslexia, a severe and persistent reading and spelling impairment, is characterized by difficulties in processing speech sounds (i.e., phonemes). Developmental dyslexia, with a prevalence of 5% to 10% in children, is the most common learning disability (1). There are various theories about the underlying cause of dyslexia. Here, we attempt to reconcile these two opposing views by testing the hypothesis that the phonological deficit in dyslexia is (i) associated with a dysfunction of the MGB, as claimed by the magnocellular theory; but (ii) that the expression of this dysfunction can be evoked by phonological tasks, as predicted by the phonological deficit and SAS hypothesis.
Fig. 1. Experimental design. Results Abnormal MGB Response in Dyslexic Subjects. Fig. 2. Discussion Methods Footnotes. Educational neuroscience: The early years. As developmental cognitive neuroscience explores mechanisms of change at the cognitive and neural systems level, a focus is beginning to emerge on the role of educational experiences in shaping the specific functional circuits that give rise to complex cognitive skills such as reading or math. Such studies mark the emergence of educational neuroscience. This interdisciplinary field tackles questions that stretch beyond the normal boundaries of what neuroscience or education research alone can address.
In doing so, it pursues insights that are of potential value to the goals of both fields of inquiry. The report by Brem et al. (1) in this issue of PNAS falls squarely within this interdisciplinary area by studying changes in the brain activity of kindergarten children across a series of several functional MRI (fMRI) scans as they engage in different educational activities between each scan. Fig. 1. Linking Brain-Activity Changes to Educational Experience Integrating Neural Systems Footnotes.
Evidence for aberrant auditory anatomy in developmental dyslexia. Evolution of working memory. The nature of human working memory (WM) has been extensively investigated, with thousands of articles and books on the topic produced over the last half-century. Some of the main findings of this research will be outlined shortly. However, we know hardly anything about how WM evolved. For that (if we are to go beyond plausible speculation), we need detailed comparative studies. However, remarkably few such studies have been conducted, as we will see.
Nevertheless, the emerging consensus about the nature of human WM allows us to frame a series of questions or alternative hypotheses concerning the possible differences between human and animal WM. Working Memory in Humans WM is the domain-general subsystem of the mind that enables one to activate and sustain (sometimes via active rehearsal) a set of mental representations for further manipulation and processing. The primary mechanism of WM is thought to be executively controlled attention (2, 6). Working Memory in Animals 1. 2. 3. 4. 5. 6. How Do I Fit through That Gap? Navigation through Apertures in Adults with and without Developmental Coordination Disorder. Abstract During everyday life we move around busy environments and encounter a range of obstacles, such as a narrow aperture forcing us to rotate our shoulders in order to pass through. In typically developing individuals the decision to rotate the shoulders is body scaled and this movement adaptation is temporally and spatially tailored to the size of the aperture.
This is done effortlessly although it actually involves many complex skills. For individuals with Developmental Coordination Disorder (DCD) moving in a busy environment and negotiating obstacles presents a real challenge which can negatively impact on safety and participation in motor activities in everyday life. However, we have a limited understanding of the nature of the difficulties encountered. Therefore, this current study considered how adults with DCD make action judgements and movement adaptations while navigating apertures. Citation: Wilmut K, Du W, Barnett AL (2015) How Do I Fit through That Gap?
Introduction. Human brain evolution: From gene discovery to phenotype discovery. Todd M. Preuss1 Author Affiliations Edited by Francisco J. Ayala, University of California, Irvine, CA, and approved April 25, 2012 (received for review February 27, 2012) Abstract The rise of comparative genomics and related technologies has added important new dimensions to the study of human evolution. The ability to sequence the whole genome of a species, along with other advances in molecular biology and in bioinformatics, have ushered in a remarkable new era of human evolutionary studies. Comparative Genetic and Molecular Background To appreciate how far we have come in this field, and what we have yet to accomplish, it is useful to note where we were in the late 1990s, just before the comparative genomics revolution.
It has long been understood that the evolution of biological features that do not fossilize, including molecules, can be reconstructed by comparing appropriately chosen species. Fig. 1. Neurobiological and Behavioral Background FOXP2: Case Study FOXP2: Gene Discovery. Intracranial dissection of word reading mechanisms. Laurent Cohena,b,c,d,e,1 Author Affiliations Reading a word gives access, within a fraction of a second, to a rich variety of information stored in memory, including meaning, grammatical features, and pronunciation. In parallel to memory retrieval, we can convert any string of letters into a sequence of speech sounds, provided that the string conforms sufficiently to the regularities of orthography (1). A prerequisite to the operation of both those reading routes is that letters and their order be rapidly and accurately identified by the visual system. The causal role of the left VOT cortex in reading was revealed by 19th century neuropsychology through the study of patients with a reading impairment following left VOT lesions (3).
The Visual Word Form Hypothesis Hirshorn et al. (5) endeavor to assess the VWF hypothesis by studying four patients implanted for intractable epilepsy. The Inner Workings of Word Reading Acknowledgments Footnotes Author contributions: L.C. wrote the paper. Mechanisms and streams for processing of “what” and “where” in auditory cortex. Mother’s voice and heartbeat sounds elicit auditory plasticity in the human brain before full gestation. Musicians have enhanced subcortical auditory and audiovisual processing of speech and music. Neural correlates of the episodic encoding of pictures and words. Neural deficits in children with dyslexia ameliorated by behavioral remediation: Evidence from functional MRI. Neuroimaging studies of word reading. Normal hearing is not enough to guarantee robust encoding of suprathreshold features important in everyday communication.
Neurophysiological origin of human brain asymmetry for speech and language. Neural systems predicting long-term outcome in dyslexia. Neural systems supporting linguistic structure, linguistic experience, and symbolic communication in sign language and gesture. Neuronal representations of distance in human auditory cortex. Sound representation in higher language areas during language generation. Subcortical differentiation of stop consonants relates to reading and speech-in-noise perception. The double identity of linguistic doubling. The fractionation of working memory. The neuroimaging of human brain function. Ventral and dorsal pathways for language.
Visual cortex entrains to sign language. Visual word processing and experiential origins of functional selectivity in human extrastriate cortex.