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Biomedical subjects

U Frith

Publications and source records attributed to U Frith.

At least 37 records · Page 2Linked to original sources
PubMed2000

Precursors of literacy delay among children at genetic risk of dyslexia.

This paper reports the literacy skills of 63 children selected as being at genetic risk of dyslexia compared with 34 children from families reporting no history of reading impairment. Fifty-seven per cent of the at-risk group were delayed in literacy development at 6 years compared with only 12% of controls. The "unimpaired" at-risk group were not statistically different from controls on most cognitive and language measures at 45 months, whereas the literacy-delayed group showed significantly slower speech and language development, although they did not differ from controls in nonverbal ability. Letter knowledge at 45 months was the strongest predictor of literacy level at 6 years. In addition, early speech and language skills predicted individual differences in literacy outcome and genetic risk accounted for unique variance over and above these other factors. The results are discussed in terms of an interactive developmental model in which semantic and phonological skills support early reading acquisition.

Child↗
PubMed1999

Interacting minds--a biological basis.

The ability to "mentalize," that is to understand and manipulate other people's behavior in terms of their mental states, is a major ingredient in successful social interactions. A rudimentary form of this ability may be seen in great apes, but in humans it is developed to a high level. Specific impairments of mentalizing in both developmental and acquired disorders suggest that this ability depends on a dedicated and circumscribed brain system. Functional imaging studies implicate medial prefrontal cortex and posterior superior temporal sulcus (STS) as components of this system. Clues to the specific function of these components in mentalizing come from single cell recording studies: STS is concerned with representing the actions of others through the detection of biological motion; medial prefrontal regions are concerned with explicit representation of states of the self. These observations suggest that the ability to mentalize has evolved from a system for representing actions.

Animals↗
PubMed1999

The neuroanatomy of autism: a voxel-based whole brain analysis of structural scans.

Autism is a biological disorder which affects social cognition, and understanding brain abnormalities of the former will elucidate the brain basis of the latter. We report structural MRI data on 15 high-functioning individuals with autistic disorder. A voxel-based whole brain analysis identified grey matter differences in an amygdala centered system relative to 15 age- and IQ-matched controls. Decreases of grey matter were found in anterior parts of this system (right paracingulate sulcus, left inferior frontal gyrus). Increases were found in posterior parts (amygdala/peri-amygdaloid cortex, middle temporal gyrus, inferior temporal gyrus), and in regions of the cerebellum. These structures are implicated in social cognition by animal, imaging and histopathological studies. This study therefore provides converging evidence of the physiological basis of social cognition.

Adult↗
PubMed1999

Fractionation of visual memory: evidence from a case with multiple neurodevelopmental impairments.

It is known that the adult visual memory system is fractionable into functionally independent cognitive subsystems, selectively susceptible to brain damage. However, it is unclear whether these cognitive subsystems can fractionate developmentally. The present study describes an investigation of visual memory of a patient (PE) with multiple developmental disorders. PE was congenitally deaf, had Gilles de la Tourette syndrome and autism, with non-verbal ability in the normal range. The patient presented with a recognition memory impairment for unknown human faces. This contrasted with his superior recognition memory for unknown buildings, landscapes and outdoor scenes. PE's memory impairment for faces could not be explained by a general deficit in face processing. Interestingly, PE also showed a recognition memory impairment for animals. These findings indicate that different domains of the visual memory system can be fractionated developmentally. In particular, it demonstrates that topographical memory can develop independently from other aspects of visual memory.

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↗
PubMed1998

Cognitive deficits in developmental disorders.

The existence of specific developmental disorders such as dyslexia and autism raises interesting issues about the structure of the normally developing mind. In these disorders distinct cognitive deficits can explain a range of behavioural impairments and have the potential to be linked to specific brain abnormalities. One possibility is that there are specific mechanisms dedicated to particular types of information processing. These mechanisms may function independently of more general information processing systems and may have a distinct anatomical basis in the brain.

Autistic Disorder↗
PubMed1997

Social behaviour in pervasive developmental disorders: effects of informant, group and "theory-of-mind".

Theory of mind skills and a range of social behaviour in everyday life were assessed in a sample of 21 children with pervasive developmental disorders and 22 normally-developing preschoolers. Parents, teachers and therapists were interviewed using the Vineland Adaptive Behaviour Scales and a new supplementary scale, the "Echelle d'Adaptation Sociale pour Enfants" (EASE). Teachers and therapists were able to differentiate subtle forms of social problems in everyday life between subgroups of children diagnosed later to have either autism (n = 13) or PDDNOS (n = 8), according to DSM-III-R (1) criteria. This study offers a (small) cross-cultural replication of recent work suggesting that differences in the mentalising skills of children with autism are reflected in the everyday social behaviour of this group. A significant effect of informant was found for the PDD group, and this effect was particularly pronounced when children with autism were considered separately. The implications of informant differences are discussed.

Activities of Daily Living↗
PubMed1997

The impact of orthographic consistency on dyslexia: a German-English comparison.

We examined reading and phonological processing abilities in English and German dyslexic children, each compared with two control groups matched for reading level (8 years) and age (10-12 years). We hypothesised that the same underlying phonological processing deficit would exist in both language groups, but that there would be differences in the severity of written language impairments, due to differences in orthographic consistency. We also hypothesized that systematic differences due to orthographic consistency should be found equally for normal and dyslexic readers. All cross-language comparisons were based on a set of stimuli matched for meaning, pronunciation and spelling. The results supported both hypotheses: On a task challenging phonological processing skills (spoonerisms) both English and German dyslexics were significantly impaired compared to their age and reading age controls. However, there were extremely large differences in reading performance when English and German dyslexic children were compared. The evidence for systematic differences in reading performance due to differences in orthographic consistency was similar for normal and for dyslexic children, with English showing marked adverse effect on acquisition of reading skills.

Adolescent↗
PubMed1996

'Theory of mind' in the brain. Evidence from a PET scan study of Asperger syndrome.

The ability to attribute mental states to others ('theory of mind') pervades normal social interaction and is impaired in autistic individuals. In a previous positron emission tomography scan study of normal volunteers, performing a 'theory of mind' task was associated with activity in left medial prefrontal cortex. We used the same paradigm in five patients with Asperger syndrome, a mild variant of autism with normal intellectual functioning. No task-related activity was found in this region, but normal activity was observed in immediately adjacent areas. This result suggests that a highly circumscribed region of left medial prefrontal cortex is a crucial component of the brain system that underlies the normal understanding of other minds.

Adult↗
PubMed1996

Is developmental dyslexia a disconnection syndrome? Evidence from PET scanning.

A rhyming and short-term memory task with visually presented letters were used to study brain activity in five compensated adult developmental dyslexics. Their only cognitive difficulty was in phonological processing, manifest in a wide range of tasks including spoonerisms, phonemic fluency and digit naming speed. PET scans showed that for the dyslexics, a subset only of the brain regions normally involved in phonological processing was activated: Broca's area during the rhyming task, temporo-parietal cortex during the short- term memory task. In contrast to normal controls these areas were not activated in concert. Furthermore the left insula was never activated. We propose that the defective phonological system of these dyslexics is due to weak connectivity between anterior and posterior language areas. This could be due to a dysfunctional left insula which may normally act as an anatomical bridge between Broca's area, superior temporal and inferior parietal cortex. The independent activation of the posterior and anterior speech areas in dyslexics supports the notion that representations of unsegmented and segmented phonology are functionally and anatomically separate.

Adult↗
PubMed1996

The neuropsychology of autism.

In this review, we aim to bring together major trends in autism research at three levels: biology, behaviour and cognition. We propose that cognitive theories are vital in neuropsychology, which seeks to make connections between brain abnormality and behavioural symptoms. Research at each of the three levels is incomplete, but important advances have been made. At the biological level, there is strong evidence for genetic factors, although the mechanism is, as yet, unknown. At the behavioural level, diagnosis and education are becoming more coherent and less controversial, although the possibility of autism subtypes has provoked new debate. At the cognitive level, three major theories are proving fruitful (mentalizing impairment, executive dysfunction and weak central coherence), although the relation and overlap between these is uncertain. Rapidly advancing technology and methodology (e.g. brain imaging, gene mapping), as tools of cognitive theory, may help to make autism one of the first developmental disorders to be understood at the neuropsychological level.

Autistic Disorder↗
PubMed1996

Cognitive explanations of autism.

A brief review of the theory of mind account of autism is presented. A lack of theory of mind in autism is well supported by empirical studies and can explain quite specifically the nature of the social communication impairments. Other characteristic behavioural features of autism, in particular perseveration and rigidity, are tackled by the hypothesis of executive function deficits. The theory of weak central coherence attempts to explain the uneven pattern of intellectual abilities seen in autistic individuals, proposing that they adopt a distinctive cognitive style. It is likely that a number of separate cognitive deficits will be identified and that these will provide clues to the underlying brain abnormalities in autism.

Autistic Disorder↗
PubMed1995

Other minds in the brain: a functional imaging study of "theory of mind" in story comprehension.

The ability of normal children and adults to attribute independent mental states to self and others in order to explain and predict behaviour ("theory of mind") has been a focus of much recent research. Autism is a biologically based disorder which appears to be characterised by a specific impairment in this "mentalising" process. The present paper reports a functional neuroimaging study with positron emission tomography in which we studied brain activity in normal volunteers while they performed story comprehension tasks necessitating the attribution of mental states. The resultant brain activity was compared with that measured in two control tasks: "physical" stories which did not require this mental attribution, and passages of unlinked sentences. Both story conditions, when compared to the unlinked sentences, showed significantly increased regional cerebral blood flow in the following regions: the temporal poles bilaterally, the left superior temporal gyrus and the posterior cingulate cortex. Comparison of the "theory of mind" stories with "physical" stores revealed a specific pattern of activation associated with mental state attribution: it was only this task which produced activation in the medial frontal gyrus on the left (Brodmann's area 8). This comparison also showed significant activation in the posterior cingulate cortex. These surprisingly clear-cut findings are discussed in relation to previous studies of brain activation during story comprehension. The localisation of brain regions involved in normal attribution of mental states and contextual problem solving is feasible and may have implication for the neural basis of autism.

Adolescent↗
PubMed1994

Language and communication in autistic disorders.

Communication problems form one of the key diagnostic criteria for autism, but there is a wide variety of manifestations. The theory that autistic individuals are unable to represent mental states can shed light on both the nature and range of communication impairments. This theory predicts that the specific communication deficit lies in the use of language to affect other minds. Language is not special in this respect, and is important only in so far as it may be used to give evidence of a speaker's thoughts and intentions. Thus, in autism, language level would be expected to relate strongly to performance on standard tests of theory of mind. Normal language acquisition appears to build upon the ability to recognize and orient towards ostensive behaviour. For this reason, it may not be necessary to postulate additional language impairments in order to explain the almost universal prevalence of language delay in children with autism. Autism, then, provides a model for studying the important distinction between language and communication, and demonstrates the vital part which mind-reading plays in normal human verbal and non-verbal interaction.

Autistic Disorder↗
PubMed1994

Sampling the form of inner experience in three adults with Asperger syndrome.

Three adults with Asperger syndrome were invited to talk about their inner experiences, using an experience sampling and interview technique. They reported thoughts primarily or solely in the form of images. By contrast, normal adults previously tested with this technique reported inner experiences of a variety of forms. The present report suggests the feasibility and potential interest of the experience sampling method with high-functioning individuals with autistic disorder.

Adaptation, Psychological↗