Biomedical subjects

N Brunswick

Publications and source records attributed to N Brunswick.

9 recordsLinked to original sources

PubMed2001

Dyslexia: cultural diversity and biological unity.

The recognition of dyslexia as a neurodevelopmental disorder has been hampered by the belief that it is not a specific diagnostic entity because it has variable and culture-specific manifestations. In line with this belief, we found that Italian dyslexics, using a shallow orthography which facilitates reading, performed better on reading tasks than did English and French dyslexics. However, all dyslexics were equally impaired relative to their controls on reading and phonological tasks. Positron emission tomography scans during explicit and implicit reading showed the same reduced activity in a region of the left hemisphere in dyslexics from all three countries, with the maximum peak in the middle temporal gyrus and additional peaks in the inferior and superior temporal gyri and middle occipital gyrus. We conclude that there is a universal neurocognitive basis for dyslexia and that differences in reading performance among dyslexics of different countries are due to different orthographies.

Adult↗

PubMed2001

Public awareness of warning signs for cancer in Britain.

BACKGROUND: The objective of this study was to establish the level of public awareness of warning signs for cancer in Britain. METHODS: An interview-based survey of a representative sample of the UK population was undertaken; 3693 men and women completed the interview (69% response rate). The data from this survey included demographic characteristics as well as recognition of the 'seven warning signs for cancer'. FINDINGS: Results revealed that recognition of signs ranged from 81% ('thickening or lump'; n = 2994) to 37% ('indigestion/difficulty swallowing'; n = 1356). On average participants identified 4.2 of the signs, with only 1.6% (n = 58) identifying all seven. There were strong associations with demographic characteristics, with better recognition being associated with being female, married, higher socioeconomic status (SES), higher income, a homeowner and having more years of education. INTERPRETATION: From these results we conclude that fewer than one in ten of the UK population can recognize seven warning signs for cancer, but the mean number recognized (4.2 signs) suggests that there is a reasonable level of public awareness. It must be cause for concern that most markers of lower SES are independently associated with poorer recognition, suggesting that public education needs to do more to narrow the inequalities in health knowledge.

Adolescent↗

PubMed2001

Awareness of risk factors for cancer among British adults.

Awareness of risk factors for five common cancers was assessed in a representative sample of 3 693 adults in the UK. Respondents were presented with a risk of 14 factors comprising 10 which have established links with various cancers (older age, many sexual partners, low fibre diet, smoking, a relative with the cancer, low fruit and vegetable diet, taking HRT/the contraceptive pill, being overweight, viruses or infection, and a high fat diet) and four so-called "mythic" causes (food additives, overhead power lines, pollution, stress). Out of 15 well-established associations between risk factors and cancers, the average number correctly identified was 5. Women and those with higher levels of education got more correct. Endorsement of mythic causes was comparatively low (less than 5% for most cancers), but were higher in men and those with less education. These results are somewhat reassuring in relation to the prevalence of erroneous beliefs, but raise considerable concern about public understanding of well established causes. Better health education will be needed to maximise public awareness of cancer prevention.

Adult↗

PubMed2000

Reading the mind in cartoons and stories: an fMRI study of 'theory of mind' in verbal and nonverbal tasks.

Previous functional imaging studies have explored the brain regions activated by tasks requiring 'theory of mind'--the attribution of mental states. Tasks used have been primarily verbal, and it has been unclear to what extent different results have reflected different tasks, scanning techniques, or genuinely distinct regions of activation. Here we report results from a functional magnetic resonance imaging study (fMRI) involving two rather different tasks both designed to tap theory of mind. Brain activation during the theory of mind condition of a story task and a cartoon task showed considerable overlap, specifically in the medial prefrontal cortex (paracingulate cortex). These results are discussed in relation to the cognitive mechanisms underpinning our everyday ability to 'mind-read'.

Adult↗

PubMed2000

Trait and state EEG indices of information processing in developmental dyslexia.

L asymmetry in beta activity in the dyslexic group, again in both tasks. Theta activity did discriminate between the two tasks in the dyslexic group. In the phonological task, task-related frontal theta in the dyslexic group was significantly different from the control group, with the former showing an increase in amplitude and the latter a decrease. In the visual task, there was no significant difference between the dyslexic and the control group, with both showing a task-related decrease in amplitude. The inter-task variations in EEG response in the dyslexic group paralleling variations in task performance are interpreted in terms of the varying engagement of a frontally-based attentional system. Inter-task consistencies of EEG response despite variations in performance are interpreted in terms of the continued application of a specific cognitive strategy.

Adolescent↗

PubMed2000

A cultural effect on brain function.

We present behavioral and anatomical evidence for a multi-component reading system in which different components are differentially weighted depending on culture-specific demands of orthography. Italian orthography is consistent, enabling reliable conversion of graphemes to phonemes to yield correct pronunciation of the word. English orthography is inconsistent, complicating mapping of letters to word sounds. In behavioral studies, Italian students showed faster word and non-word reading than English students. In two PET studies, Italians showed greater activation in left superior temporal regions associated with phoneme processing. In contrast, English readers showed greater activations, particularly for non-words, in left posterior inferior temporal gyrus and anterior inferior frontal gyrus, areas associated with word retrieval during both reading and naming tasks.

Adult↗

PubMed2000

Abnormal functional activation during a simple word repetition task: A PET study of adult dyslexics.

Eight dyslexic subjects, impaired on a range of tasks requiring phonological processing, were matched for age and general ability with six control subjects. Participants were scanned using positron emission tomography (PET) during three conditions: repeating real words, repeating pseudowords, and rest. In both groups, speech repetition relative to rest elicited widespread bilateral activation in areas associated with auditory processing of speech; there were no significant differences between words and pseudowords. However, irrespective of word type, the dyslexic group showed less activation than the control group in the right superior temporal and right post-central gyri and also in the left cerebellum. Notably, the right anterior superior temporal cortex (Brodmann's area 22 [BA 22]) was less activated in each of the eight dyslexic subjects, compared to each of the six control subjects. This deficit appears to be specific to auditory repetition as it was not detected in a previous study of reading which used the same sets of stimuli (Brunswick, N., McCrory, E., Price, C., Frith, C.D., & Frith, U. [1999]. Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz? Brain, 122, 1901-1917). This implies that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural). Other studies of normal subjects indicate that attending to the phonetic structure of speech leads to a decrease in right-hemisphere processing. Lower right hemisphere activation in the dyslexic group may therefore indicate less processing of non-phonetic aspects of speech, allowing greater salience to be accorded to phonological aspects of attended speech.

Adult↗

PubMed1999

Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz?

Two groups of male university students who had been diagnosed as dyslexic when younger, and two groups of control subjects of similar age and IQ to the dyslexics, were scanned whilst reading aloud and during a task where reading was implicit. The dyslexics performed less well than their peers on a range of literacy tasks and were strikingly impaired on phonological tasks. In the reading aloud experiment, simple words and pseudowords were presented at a slow pace so that reading accuracy was equal for dyslexics and controls. Relative to rest, both normal and dyslexic groups activated the same peri- and extra-sylvian regions of the left hemisphere that are known to be involved in reading. However, the dyslexic readers showed less activation than controls in the left posterior inferior temporal cortex [Brodmann area (BA) 37, or Wernicke's Wortschatz], left cerebellum, left thalamus and medial extrastriate cortex. In the implicit reading experiment, word and pseudoword processing was contrasted to visually matched false fonts while subjects performed a feature detection paradigm. The dyslexic readers showed reduced activation in BA 37 relative to normals suggesting that this group difference, seen in both experiments, resides in highly automated aspects of the reading process. Since BA 37 has been implicated previously in modality-independent naming, the reduced activation may indicate a specific impairment in lexical retrieval. Interestingly, during the reading aloud experiment only, there was increased activation for the dyslexics relative to the controls in a pre-motor region of Broca's area (BA 6/44). We attribute this result to the enforced use of an effortful compensatory strategy involving sublexical assembly of articulatory routines. The results confirm previous findings that dyslexic readers process written stimuli atypically, based on abnormal functioning of the left hemisphere reading system. More specifically, we localize this deficit to the neural system underlying lexical retrieval.

Adult↗

PubMed1994

Auditory event-related potentials, dichotic listening performance and handedness as indices of lateralisation in dyslexic and normal readers.

Evidence suggests that children with developmental dyslexia have poor phonological processing skills, are less likely to show lateralised activation during the processing of verbal information than children with normal reading ability and tend towards the left of the handedness continuum. The present study investigated this relationship between cerebral lateralisation and reading ability in children with and without dyslexia, directly using a dichotic listening paradigm with contemporaneous recording of auditory evoked potentials and indirectly using measures of hand preference and hand skill. The two groups were significantly different on a phonemic awareness task, particularly with reference to rime rather than phoneme onset. The two groups performed equally well on the dichotic listening task. However, normal readers produced significantly greater N100 amplitudes in the left temporal region during dichotic listening than the dyslexics who displayed approximately equivalent levels of amplitude bilaterally. In terms of hand preference the dyslexics were significantly less right-hand preferent than the controls, although the groups did not differ on a measure of right/left hand skill. The AEP lateralisation indices and the hand preference scores were significantly related to phonemic awareness performance. The different patterns of AEP activity produced by the two groups of children during the dichotic listening task and the differences in hand preference may be related to abnormal cerebral lateralisation of language functions. The failure of the dichotic listening task to discriminate between the two groups in spite of evidence of differences in cortical activation suggests that the processing difficulties which may be indexed by these differences in cortical activation affect the reading process at a later stage than that tapped by dichotic listening.

Child↗