The development of reading skill and bases of developmental dyslexia were explored using connectionist models. Four issues were examined: the acquisition of phonological knowledge prior to reading, how this knowledge facilitates learning to read, phonological and non phonological bases of dyslexia, and effects of literacy on phonological representation. Compared with simple feedforward networks, representing phonological knowledge in an attractor network yielded improved learning and generalization. Phonological and surface forms of developmental dyslexia, which are usually attributed to impairments in distinct lexical and nonlexical processing “routes,” were derived from different types of damage to the network. The results provide a computationally explicit account of many aspects of reading acquisition using connectionist principles.

the properties of distributed network models, and support this account by demonstrating that an implemented simulation closely approximates the empirical findings despite the absence of expectancy-based processes and postlexical semantic matching. The results suggest that distributed network models can provide a viable single-mechanism account of lexical processing. Introduction It is well-established that people are faster and more accurate to read a word (e.g., BUTTER) when it is preceded by a related word (e.g., BREAD) compared with when it is preceded by an unrelated word (e.g., DOCTOR; The research was supported by an NIMH FIRST award (MH55628) to the first author and by NIMH Training Grant 5T32MH19102 and NICHD Grant 80258. The computational simulation was run using customized software written within the Xerion simulator (version 3.1) developed by Drew van Camp, Tony Plate, and Geoff Hinton at the Univers

this paper will be to review the scientific studies that led to 5 the development of these new remediation techniques, based on neuroplasticity research, as well as the outcome data derived from controlled laboratory studies and field trials aimed at assessing the efficacy of these new training methods. Early studies focusing on the etiology of developmental language impairments date back to the early 1960s. In a classic paper, Benton (1964) hypothesized that central auditory processing deficits may characterize many children with developmental dysphasia, now referred to as specific language impairment (SLI). Subsequent studies focused on one aspect of central auditory processing, that is, sequencing or temporal order judgement (TOJ) deficits. Pursuing these early studies, Tallal and Piercy (1973 a; 1973 b) set out to investigate further the auditory perceptual abilities of children with developmental dysphasia. In addition to an experimental temporal order judgement (TOJ) task, they included a frequency discrimination task as a control condition. In both the TOJ and the frequency discrimination task the identical set of stimuli were presented. Stimuli consisted of two 75 msec duration complex tones that differed in fundamental frequency (100Hz vs 305Hz). All possible combinations of these two stimuli were presented in pairs. The two tones in the pair were separated by a silent interval of varying duration (inter-stimulus interval -- ISI). In the TOJ task the child was trained to press two response buttons, to indicate the temporal order of the two tones. If the same tone was presented twice, the button representing that tone was pressed twice. If two different 6 tones were presented, the child was trained to indicate which one came first and which second, using the...

y ability in children are primarily associated with problems in phonological processing, whereas deficits in rapid visual ability in children are primar- ily associated with problems in orthographic processing (Farmer & Klein, 1995). In contrast to the children, the adults showed a strong relation between rapid auditory ability and both orthographic and phonological processing. These results suggest that continued deficits in auditory ability may have a pervasive and negative impact on word processing in general. In addition, adults did not exhibit a relation between rapid visual ability and orthographic-processing problems. Orthographic-processing deficits may Requests for reprints should be sent to James R. Booth, Department of Communication Sciences and Disorders, Northwestern University, 2299 North Campus Drive, Evanston, IL 60208-3560. E-mail: j-booth@nwu.edu ORTHOGRAPHIC AND PHONOLOGICAL PROCESSING 103 102 BOOTH ET AL.<F11.86

The current review constitutes the first comprehensive look at the possibility that the mismatch negativity (MMN, the deflection of the auditory ERP/ERF elicited by stimulus change) might be generated by so-called fresh-afferent neuronal activity. This possibility has been repeatedly ruled out for the past 30 years, with the prevailing theoretical accounts relying on a memory-based explanation instead. We propose that the MMN is, in essence, a latency- and amplitude-modulated expression of the auditory N1 response, generated by fresh-afferent activity of cortical neurons

It is now well-established that there is a causal connection between children’s phonological skills and their acquisition of reading and spelling. Here we study low-level auditory processes that may underpin the development of phonological representations in children. Dyslexic and control children were given a battery of phonological tasks, reading and spelling tasks and auditory processing tasks. Potential relations between deficits in dyslexic performance in the auditory processing tasks and phonological awareness were explored. It was found that individual differences in auditory tasks requiring amplitude envelope rise time processing explained significant variance in phonological processing. It is argued that developmentally, amplitude envelope cues may be primary in establishing well-specified phonological representations, as these cues should yield important rhythmic and syllable-level information about speech.

Abstract. Abnormal auditory temporal processing might be an underlying deficit in language disabilities. The auditory temporal-order threshold, one measure for temporal processing abilities, is defined as the shortest time interval between two acoustic events necessary for a person to be able to identify the correct temporal order. In our study, we examined the reliability of the auditory temporal-order threshold during a one-week period and over a time interval of four months in normally developing children aged 5 to 11 years. The results of our method show that children younger than 7 years have difficulties performing the task successfully. The reliability of the assessment of the temporal-order threshold during a period of one week is only moderate, and its stability over a time interval of four months is low. The results show that auditory-order thresholds in children have to be treated with caution. A high temporal-order threshold does not necessarily predict disabilities in temporal processing. Key words: auditory temporal processing, temporal-order discrimination, reliability of measurement, developmental effects, feasibility of measurement 388 D. Berwanger et al.

& Individuals with developmental language disabilities, including developmental dyslexia and specific language impairment (SLI), exhibit impairments in processing rapidly presented auditory stimuli. It has been hypothesized that these deficits are associated with concurrent deficits in speech perception and, in turn, impaired language development. Additionally, postmortem analyses of human dyslexic brains have revealed the presence of focal neocortical malformations such as cerebrocortical microgyria. In an initial study bridging these research domains, we found that male rats with induced microgyria were impaired in discriminating rapidly presented auditory stimuli. In order to further assess this anatomical-- behavioral association, we designed two experiments using auditory-reflex modification. These studies were intended to assess whether auditory processing deficits in microgyric male rats would be seen in threshold detection of a silent gap in white noise, and in oddball detection of a two-tone stimulus of variable duration. Results showed no differences between sham and microgyric subjects on gap detection, but did show that microgyric subjects were impaired in the discrimination of two-tone stimuli presented in an oddball paradigm. This impairment was evident for stimuli with total duration of 64 msec or less, while both groups were able to discriminate stimuli with duration of 89 msec or greater. The current results further support the relationship between malformations of the cerebral cortex and deficits in rapid auditory processing. They also suggest that the parameters characterizing rapid auditory processing deficits for a specific task may be influenced by stimulus features and/or cognitive demand of that particular task. &

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