Contribution of visual and semantic proximity to identification performance in a viral encephalitis patient

Neuropsychological and psychiatric profiles in acute encephalitis in adults

Acute encephalitis is an inflammation of brain tissue that can result from activity in the central nervous system (CNS) of a number of viruses. Although the neurological and psychiatric effects of encephalitis in the acute phase of the illness are well-known (Caroff, Mann, Gliatto, Sullivan, & Campbell, 2001), larger scale studies of the pattern of neuropsychological and psychiatric impairment following recovery from the acute inflammatory phase are less apparent. This paper reports the results of neuropsychological testing with a range of standardised cognitive measures in a case series of long-term post-acute participants. Psychiatric abnormality is examined using the SCL-90-R self-report scale of distress (Derogatis, 1983). We also examined the role of emerging insight in the aetiology of depression in this population. Two clusters of cognitive dysfunction were observed, one group of primarily herpes simplex cases showing a severe generalised deficit across a number of cognitive domains and a second cluster showing a variety of more isolated disorders of executive function. Abnormally high levels of distress were reported by participants, with depression, obsessive-compulsive symptoms, interpersonal sensitivity and phobic anxiety most significantly increased. Depression was found to be least severe in those with most accurate insight into their problems. Examining the correlations between cognitive and psychiatric test results demonstrates a relationship between depression and interpersonal anxiety and specific cognitive measures. Obsessive-compulsive behaviour and phobic anxiety, however, appear to exist independently of the assessed cognitive deficits.

The influence of visual and nonvisual attributes in visual object identification

To elucidate the role of visual and nonvisual attribute knowledge on visual object identification, we present data from three patients, each with visual object identification impairments as a result of different etiologies. Patients were shown novel computer-generated shapes paired with different labels referencing known entities. On test trials they were shown the novel shapes alone and had to identify them by generating the label with which they were formerly paired. In all conditions the same triad of computer-generated shapes were used. In one condition, the labels (banjo, guitar, violin) referenced entities that were both visually similar and similar in terms of their nonvisual attributes within semantics. In separate conditions we used labels (e.g., spike, straw, pencil or snorkel, cane, crowbar) that referenced entities that were similar in terms of their visual attributes but were dissimilar in terms of their nonvisual attributes. The results revealed that nonvisual attribute information profoundly influenced visual object identification. Our patients performed significantly better when attempting to identify shape triads whose labels referenced objects with distinct nonvisual attributes versus shape triads whose labels referenced objects with similar nonvisual attributes. We conclude that the nonvisual aspects of meaning must be taken into consideration when assessing visual object identification impairments.