Biomedical subjects

C Whatmough

Publications and source records attributed to C Whatmough.

4 recordsLinked to original sources

PubMed2003

The semantic category effect increases with worsening anomia in Alzheimer's type dementia.

A large number of patients (n=72) with probable Alzheimer's type dementia (DAT) and mild cognitive impairment (MCI) carried out a picture naming task which comprised stimuli from biological and nonbiological categories. The results were stratified into five ranges of overall naming ability. Every group except those with scores within the range of elderly normal individuals demonstrated better nonbiological naming than biological naming, an effect which increased with worsening impairment. In general, patients diagnosed with other dementia (n=15) did not fit well within the pattern of the DAT/MCI participants, except those known to have a significant semantic impairment. A category effect favoring nonbiological items appears to be robust and produce a predictable pattern across progressive levels of impairment in AD.

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PubMed2002

Dissociable brain regions process object meaning and object structure during picture naming.

Although imaging studies have indicated that the fusiform gyrus is important in tasks of picture naming, whether this region encodes an object's structure or its meaning is not clear. We used positron emission tomography to examine cerebral blood flow (CBF) changes in response to a picture naming task that varied on two dimensions: familiarity (or difficulty: hard vs easy) and category (tools vs animals). Results show that although familiarity effects are present in the frontal and left lateral posterior temporal cortex, they are absent from the fusiform gyrus. This provides strong evidence that the processing carried out in the fusiform gyrus relates to an object's structure, not to its meaning, and that the left posterior middle temporal gyrus instantiates in part the semantic network that represents the object's meaning.

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PubMed2001

The spectrum of category effects in object and action knowledge in dementia of the Alzheimer's type.

The validity and origin of category effects in the anomia demonstrated by individuals with dementia of the Alzheimer's type (DAT) remains controversial. Twenty DAT subjects were tested with picture naming and semantic association judgment tests. Picture and word stimuli were drawn from biological, nonbiological, and actions-verbs categories, all of equal difficulty and previously normed on elderly controls. DAT subjects made significantly more naming and semantic judgment errors in the biological category than in the nonbiological category. They were relatively more accurate in naming and making judgments for actions-verbs when presented as words or as 5-s animations. When line drawings of actions were shown for naming, performance deteriorated significantly. Converging results from these 2 tasks provide strong evidence for a semantic memory impairment preferentially affecting biological items to a greater extent than nonbiological items or action verbs in DAT.

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PubMed1999

Cross-modal priming evidence for phonology-to-orthography activation in visual word recognition.

Subjects were asked to indicate which item of a word/nonword pair was a word. On critical trials the nonword was a pseudohomophone of the word. RTs of dyslexics were shorter in blocks of trials in which a congruent auditory prime was simultaneously presented with the visual stimuli. RTs of normal readers were longer for high frequency words when there was auditory priming. This provides evidence that phonology can activate orthographic representations; the size and direction of the effect of auditory priming on visual lexical decision appear to be a function of the relative speeds with which sight and hearing activate orthography.

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