Computation of tactile object properties requires the integrity of praxic skills.

We describe a series of experiments to examine the tactile identification of objects over the course of neurological recovery in a patient with an intracerebral haemorrhage involving the left inferior and superior parietal lobe. Tactile agnosia in this case involved the ipsilesional as well as the contralesional hand, allowing us to observe the effects of dominant parietal lobe damage without the confounding effects of hemiparesis. The findings demonstrate that both apraxia and tactile apperceptive agnosia may result from a unilateral lesion involving the left parietal lobe.

Abstract and concrete concepts have structurally different representational frameworks.

The architecture supporting our conceptual knowledge of abstract words has remained almost entirely unexplored. By contrast, a vast neuropsychological, neurolinguistic and neuroimaging literature has addressed questions relating to the structure of the semantic system underpinning our knowledge of concrete items (e.g.

A circumscribed refractory access disorder: A verbal semantic impairment sparing visual semantics.

We report the case of a patient (AZ) with a semantic refractory access dysphasia. On matching-to-sample tests assessing comprehension of the spoken word, AZ shows all the hallmarks of a refractory access disorder, namely inconsistent performance on repeated testing and sensitivity to both presentation rate and the semantic similarity between competing responses. However, on tasks examining her visual knowledge, such as matching two structurally different exemplars of the same item, AZ's performance is quantitatively and qualitatively different.

The semantic organisation of proper nouns: the case of people and brand names.

We describe the performance of a patient (AZ) with a semantic refractory access disorder on a series of experiments probing comprehension of two broad proper noun categories, namely person names and brand names. By inducing and manipulating the semantic relatedness effects which are commonly observed in semantic refractory access patients, we demonstrate that famous person knowledge is primarily organised by occupation, whilst knowledge of brands is organised by product type. For instance, we show that AZ has significantly greater difficulty identifying a famous person from among distractor personalities who have the same occupation (e.

Spatial coding of semantic information: knowledge of country and city names depends on their geographical proximity.

We report the case of a patient, A.Z., with a refractory disorder of semantic processing.

The selective impairment of fruit and vegetable knowledge:amultiple processing channels account of fine-grain category specificity.

We report the case of a gentleman, FAV, who developed a grave anomia and selective comprehension deficit following a left temporo-occipital infarction. His word retrieval abilities were significantly more impaired for living things than for man-made artefacts. There was no difference between his performance when naming to confrontation and naming to verbal description.

Preserved calculation skills in a case of semantic dementia.

We present the case of a patient, BET, with a profound semantic dementia who shows a selective preservation of many aspects of number knowledge. In the context of an otherwise global loss of visual and verbal semantic knowledge, our patient demonstrates relatively intact number processing and numerical calculation in both the verbal and visual domain. More remarkably, BET is able to harness her intact calculation skills to number problem solving tasks.