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Biomedical subjects

Usha Goswami

Publications and source records attributed to Usha Goswami.

At least 19 recordsLinked to original sources
PubMed2006

Genotoxicity of cadmium in marine diatom Chaetoceros tenuissimus using the alkaline Comet assay.

Genotoxic effects of cadmium on phytoplankton Chaetoceros tenuissimus have been evaluated using DNA damage by Comet assay. Cadmium concentrations ranging from 2.4 to 10 mg/l were used to evaluate the effects. Results showed that as the concentration of Cd increased growth of the diatom decreased. Alkaline single-cell gel electrophoresis (Comet assay) method, which is highly sensitive in detection of DNA damage in eukaryotic cells, was used to observe genomic changes in marine diatom cells. DNA damage was measured as percent number of comets and normal cells. 65% cells were found to be damaged at 10 mg/l concentration of Cd as compared to 23% in 2.4 mg/l and only 5% in controls. More than 50% apoptotic cells were observed on 8th day at 10 mg/l and 12th day at 7.5 mg/l concentrations. At lower Cd concentrations (4.5 mg/l and below) the damage was below 30% till the last day. This suggested that higher Cd levels have early damaging effects on cell nuclear material and that % injury increases with advancement of exposure period. One advantage of use of C. tenuissimus is the ease with which it can be cultured in a defined medium. C. tenuissimus diatom can be used as an in vivo model for ecogenotoxicity assessment using the Comet assay.

Animals↗
PubMed2006

DNA damage in male gonad cells of Green mussel (Perna viridis) upon exposure to tobacco products.

DNA damage (determined by the Comet Assay) and the occurrence of deformed nuclei were measured as endpoints of genotoxicity in male gonad cells of the marine mussel (Perna viridis). Upon exposure of the organism to varying concentrations of extracts of smoked and non-smoked cigar tobacco over a period of 16 days, DNA damage was found to be highest in marine mussels exposed to extracts of smoked cigar tobacco. Conversely, more deformed nuclei were detected in marine mussels exposed to extracts of non-smoked cigar tobacco. The level of DNA damage and the number of deformed nuclei reach a maximum at day 12 of exposure to both extracts but decrease thereafter. This phenomenon is attributed to the organism's capacity to maintain the integrity of its genetic material upon exposure to potential genotoxicants present in the tobacco extracts. A dose response in DNA damage and deformed nuclei was also detected in isolated gonad cells upon in vitro exposure to hydrogen peroxide a known DNA strand breaking agent. The results of this study indicate that the DNA in male gonad cells of the marine mussel is damaged upon exposure to genotoxicants, and suggests the suitability of the organism for future investigations into the effect of such agents on its reproductive capacities.

Animals↗
PubMed2006

Neuroscience and education: from research to practice?

Cognitive neuroscience is making rapid strides in areas highly relevant to education. However, there is a gulf between current science and direct classroom applications. Most scientists would argue that filling the gulf is premature. Nevertheless, at present, teachers are at the receiving end of numerous 'brain-based learning' packages. Some of these contain alarming amounts of misinformation, yet such packages are being used in many schools. What, if anything, can neuroscientists do to help good neuroscience into education?

Animals↗
PubMed2006

Becoming literate in different languages: similar problems, different solutions.

The teaching of reading in different languages should be informed by an effective evidence base. Although most children will eventually become competent, indeed skilled, readers of their languages, the pre-reading (e.g. phonological awareness) and language skills that they bring to school may differ in systematic ways for different language environments. A thorough understanding of potential differences is required if literacy teaching is to be optimized in different languages. Here we propose a theoretical framework based on a psycholinguistic grain size approach to guide the collection of evidence in different countries. We argue that the development of reading depends on children's phonological awareness in all languages studied to date. However, we propose that because languages vary in the consistency with which phonology is represented in orthography, there are developmental differences in the grain size of lexical representations, and accompanying differences in developmental reading strategies across orthographies.

Child↗
PubMed2006

The foundations of psychological understanding.

In this paper, I review some recent submissions to Developmental Science that advance our understanding of psychological development. More and more submissions to the journal explore the origins of knowledge and, for psychological knowledge, such origins are multiple. Here I consider the contribution of mechanisms such as contingency detection, gaze following and gaze monitoring, social referencing and joint attention to emergent psychological understanding. I also consider infant understanding of goal-directed action, and the intimate connection between language acquisition and psychological development. The centrality of intention-reading skills to both language and social cognition is highlighted.

Attention↗
PubMed2005

The effects of spelling consistency on phonological awareness: a comparison of English and German.

Within alphabetic languages, spelling-to-sound consistency can differ dramatically. For example, English and German are very similar in their phonological and orthographic structure but not in their consistency. In English the letter a is pronounced differently in the words bank, ball, and park, whereas in German the letter a always has the same pronunciation (e.g., Ball, Park, Bank). It is often argued that reading acquisition has a reciprocal effect on phonological awareness. As reading is acquired, therefore, spoken language representation may be affected differently for English and German children. Prior to literacy acquisition, however, phonological representation in English and German children should be similar due to the similar phonological structure of the two languages. We explored this hypothesis by comparing phonological awareness at the rime and phoneme levels in prereaders and beginning readers in English and German. Similar developmental effects were indeed observed in prereaders, but differential effects had emerged within the first year of reading instruction.

Awareness↗
PubMed2005

Reading acquisition, developmental dyslexia, and skilled reading across languages: a psycholinguistic grain size theory.

The development of reading depends on phonological awareness across all languages so far studied. Languages vary in the consistency with which phonology is represented in orthography. This results in developmental differences in the grain size of lexical representations and accompanying differences in developmental reading strategies and the manifestation of dyslexia across orthographies. Differences in lexical representations and reading across languages leave developmental "footprints" in the adult lexicon. The lexical organization and processing strategies that are characteristic of skilled reading in different orthographies are affected by different developmental constraints in different writing systems. The authors develop a novel theoretical framework to explain these cross-language data, which they label a psycholinguistic grain size theory of reading and its development.

Aptitude↗
PubMed2005

Phonological awareness in deaf children who use cochlear implants.

A short-term longitudinal study was conducted to investigate possible benefits of cochlear implant (CI) use on the development of phonological awareness in deaf children. Nineteen CI users were tested on 2 occasions. Two groups of deaf children using hearing aids were tested once: 11 profoundly deaf and 10 severely deaf children. A battery of tests was designed to investigate syllable, rhyme, and phoneme awareness. Syllable awareness in the CI users was equivalent to that of the severely deaf group, and rhyme and phoneme awareness was similar to that of the profoundly deaf children using hearing aids. CI use affords some benefit to the development of phonological awareness. The results from this study indicate that this enhancement is first observable at the syllable level.

Awareness↗
PubMed2005

Phonological similarity neighborhoods and children's short-term memory: typical development and dyslexia.

In this article, we explore whether structural characteristics of the phonological lexicon affect serial recall in typically developing and dyslexic children. Recent work has emphasized the importance of long-term phonological representations in supporting short-term memory performance. This occurs via redintegration (reconstruction) processes, which show significant neighborhood density effects in adults. We assessed whether serial recall in children was affected by neighborhood density in word and nonword tasks. Furthermore, we compared dyslexic children with typically developing children of the same age or reading level. Dyslexic children are held to have impaired phonological representations of lexical items. These impaired representations may impair or prevent the use of long-term phonological representations to redintegrate short-term memory traces. We report significant rime neighborhood density effects for serial recall of both words and nonwords, for both dyslexic and typically developing children.

Attention↗
PubMed2004

Deficits in beat perception and dyslexia: evidence from French.

Recent research has suggested a novel link between deficits in the perception of cues relevant to speech rhythm (i.e., deficits in amplitude envelope rise time processing, or beat perception) and the phonological deficits seen in most dyslexic children. In this research, we investigated whether these beat perception deficits were specific to a stress-timed language, such as English, or whether they would generalize to languages with different rhythmic properties, such as French. Eighteen dyslexics, 18 reading level controls, and 20 chronological age controls were tested on a battery of phonological tasks, reading tasks and psychoacoustic tests. The results suggest that deficits in the perception of cues important for speech rhythm may be universal in developmental dyslexia.

Child↗
PubMed2004

Auditory processing skills and phonological representation in dyslexic children.

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.

Anomia↗
PubMed2004

Neuroscience and education.

Neuroscience is a relatively new discipline encompassing neurology, psychology and biology. It has made great strides in the last 100 years, during which many aspects of the physiology, biochemistry, pharmacology and structure of the vertebrate brain have been understood. Understanding of some of the basic perceptual, cognitive, attentional, emotional and mnemonic functions is also making progress, particularly since the advent of the cognitive neurosciences, which focus specifically on understanding higher level processes of cognition via imaging technology. Neuroimaging has enabled scientists to study the human brain at work in vivo, deepening our understanding of the very complex processes underpinning speech and language, thinking and reasoning, reading and mathematics. It seems timely, therefore, to consider how we might implement our increased understanding of brain development and brain function to explore educational questions.

Brain↗
PubMed2003

Why theories about developmental dyslexia require developmental designs.

This article examines the importance of developmental designs in dyslexia research using a neuroconstructivist framework. According to neuroconstructivism, the lowest level of impairment should be identified as early as possible, and developmental effects on higher-level cognition examined longitudinally. A number of recent studies proposing candidate low-level impairments have not used such developmental designs. The role of normal variation in postulated causal factors on development is ignored, inadequate control groups are used, and the nature and timing of environmental inputs are not measured, even though reading is taught systematically and both reading acquisition and dyslexia vary with orthography. It is suggested here that only a phonological deficit arising from low-level auditory processing problems meets the criteria for a neuroconstructivist approach.

Journal Article↗
PubMed2003

Phonological neighbourhood density: effects in a rhyme awareness task in five-year-old children.

Phonological awareness skills are critical for reading acquisition, yet relatively little is known about the origins of phonological awareness. This study investigates one plausible source of the emergence of phonological awareness, phonological neighbourhood density. As vocabulary grows, the number of similar-sounding words in the child's mental lexicon increases. This could create developmental pressure to develop awareness of sub-units within words such as syllables, rhymes and phonemes. If this is the case, then neighbourhood density effects should be discernible in phonological awareness tasks. Children should be more successful in these tasks with words from dense phonological neighbourhoods, as they should show greater awareness of sub-units within these words. We investigated this hypothesis in a group of 48 five-year-old children, most of whom were pre-readers. The five-year-olds with a high vocabulary age showed neighbourhood density effects in a rhyme oddity task, but five-year-olds with lower vocabulary ages did not. This suggests that vocabulary acquisition and consequent neighbourhood density effects are indeed one source of the emergence of phonological awareness skills in pre-readers.

Awareness↗
PubMed2002

Amplitude envelope onsets and developmental dyslexia: A new hypothesis.

A core difficulty in developmental dyslexia is the accurate specification and neural representation of speech. We argue that a likely perceptual cause of this difficulty is a deficit in the perceptual experience of rhythmic timing. Speech rhythm is one of the earliest cues used by infants to discriminate syllables and is determined principally by the acoustic structure of amplitude modulation at relatively low rates in the signal. We show significant differences between dyslexic and normally reading children, and between young early readers and normal developers, in amplitude envelope onset detection. We further show that individual differences in sensitivity to the shape of amplitude modulation account for 25% of the variance in reading and spelling acquisition even after controlling for individual differences in age, nonverbal IQ, and vocabulary. A possible causal explanation dependent on perceptual-center detection and the onset-rime representation of syllables is discussed.

Articulation Disorders↗