Neurocognitive Complications of HIV Disease

Neurocognitive complications are the most common sequelae of HIV infection if the full spectrum of HIV disease—from initial seroconversion to death from advanced AIDS—is considered. Though resembling subcortical neurological disorders from a neuropsychological standpoint, the presentation is variable, and almost any pattern can be seen. Although neuropsychological impairment is often subtle, it can affect day-to-day life and is associated with earlier mortality. It is not clear if milder forms of neurocognitive disturbance necessarily presage advanced dementia, and current data suggest a two-factor model: a subacute relapsing-remitting condition that can occur at any stage of HIV disease and a progressive, more fulminant dementia. The pathological substrates of these conditions are not well characterized, although recent data support the notion that synaptodendritic damage underlies the neuropsychological impairment, and may precede the neuronal loss and other pathological features more characteristic of HIV encephalitis. Some reversibility of neurocognitive disturbance has been reported with zidovudine therapy, though the data are not consistent. New regimens involving protease inhibitors need to be evaluated in terms of benefit to the central nervous system because many drugs of this class do not penetrate the blood-brain barrier efficiently. Finally, studies utilizing experimental treatments that may affect the putative mechanisms of neural injury are in progress.     

Perception without attention: results of a new method.

Having found by the use of a new method for examining perception without attention that grouping and texture segregation do not seem to occur (see Mack, Tang, Tuma, Kahn, & Rock (1992) Cognitive Psychology, 24, we go on to ask what is perceived without attention using this new method. Our subjects receive only one inattention trial in a sequence of trials involving a visual distraction task. In addition to the distraction task in the inattention trial, subjects received a stimulus of which they had no prior knowledge or expectation and were questioned or tested directly afterward for their perception of that stimulus. Two subsequent trials containing test stimuli serve as within-subject controls. The results of a series of experiments indicate that the presence of one or more stimulus objects and their locations are preattentively perceived, as is their color, but shape is not. Because individual items are detected without attention, we conclude that perceptual organization is initially based on a principle in which connected regions of uniform stimulation are inferred to be discrete units (the principle of uniform connectedness). One striking, unexpected finding is that without attention many subjects have no awareness at all of the stimulus object, an effect we call inattentional blindness.     

Are inaccuracies in self-reported weight motivated distortions?

The accuracy of self-reported weight and the motivation of distorted reporting were studied among 169 female and 101 male college students. Although subjects were moderately accurate in their weight estimates, errors reflected women's underreporting, men's overreporting, and heavier persons' underreporting. With body mass controlled, most motivational variables had little explanatory value.     

The evolution of chronic back pain problems: a longitudinal study.

A longitudinal evaluation of the recovery from an acute back pain episode was undertaken on 117 sufferers, with assessments at the onset, 3 and 6 months. The number of individuals still reporting pain at 6 months, and therefore qualifying for 'chronic pain', was considerably higher than expected (40%). At 6 months, the persisting pain problems were found to be moderate to severe in intensity in approx. 20% of cases. Despite the pain, the chronic sufferers showed gradual continuing adjustments to it, re-establishing activities despite pain. Most of the change in the pain components (cognitive, subjective, behavioral, depression, anxiety) occur in the first 3 months, after which considerable stability is evident in the residual problem. In contrast, the impact of the pain and the consequent disability decline more markedly and continue to do so right up to the 6 month point. There was no evidence of chronic pain evolving and growing, but rather of a persistence of the acute presentation.     

The prevention of chronic pain and disability: a preliminary investigation.

A preliminary investigation was undertaken on 117 acute back pain cases, to assess the utility of counseling at the acute stage upon the course of recovery over the subsequent 6 months. In addition, the extent to which psychological reactions to acute injury would allow the 'tagging' of individuals at risk for chronic pain problems, was studied. The minimal rehabilitation counseling proved inadequate to effect the course of recovery, but remarkably accurate predictions were possible at the sub-chronic point (3 months) as to who would make complete recoveries.     

Irrelevance of sample stimuli and directed forgetting in pigeons

A successive matching procedure was used to investigate which aspect of the test-omission procedure is responsible for establishing a postsample stimulus as a cue to forget in pigeons. It was found that a postsample stimulus that reliably followed a sample that was irrelevant to performance functioned as a cue to forget. This result was obtained regardless of whether termination of that postsample stimulus was followed by reinforcement or by the presentation of sample-independent discriminative stimuli. It was also found that a postsample stimulus that functioned as a cue to forget at the beginning of training lost that function when it was repeatedly presented on trials in which the sample was relevant to performance. These findings reveal that (a) neither a reduction in reinforcement rate nor the omission of the opportunity for discriminated responding is necessary to establish an effective cue to forget and (b) irrelevance of the sample to performance is a sufficient condition to establish a cue to forget. These results suggest that a postsample stimulus that is presented on trials in which remembering the sample is not reinforced differentially will come to set the occasion for not remembering the sample.     

Language,social ecology and experience

Experience is structured by thoughts which are composed of general concepts and conceptions of objects. Both of these elements of thought are rule‐governed and rest on norms which are shared by thinkers. Concepts and conceptions of objects as the elements of thoughts whose content is essentially communicable plausibly rest on abilities tied to the use of linguistic terms. This suggests that language plays an active part in structuring human experience and cognition as suggested by both Vygotsky and Luria. The role of language in thought implies that the human brain which is the information processing structure realizing thoughts is itself subject to shaping by the social milieu. Neural network theory suggests that this might proceed via the use of cue stimuli based on the responses of other human beings and, therefore, supports the view that cognitive neuroscience may be radically mistaken in thinking that it can provide an individualistic analysis of human mental life.     

Stimulus control of information processing in pigeon short-term memory

Six pigeons were trained initially on a delayed successive matching-to-sample task using red and green fields as sample and test stimuli. Following acquisition, each sample was followed either by a vertical line (“remember” cue), which indicated that sample memory would be tested, or by a horizontal line (“forget” cue), which indicated that sample memory would not be tested. During the experiments, sample memory on forget trials was tested occasionally. A series of five experiments revealed: (a) better retention on remember trials than on forget trials, (b) increased effectiveness of a forget cue when it followed closely sample offset, (c) more rapid forgetting over a retention interval ranging from 3 to 6 sec on forget trials than on remember trials, (d) a “cancellation” effect in which a remember cue which followed immediately the offset of a forget cue attenuated markedly the effectiveness of the forget cue, and (e) an “insulation” effect in which the effectiveness of a forget cue was reduced considerably when presented after a remember cue. It was concluded that pigeons actively process or rehearse the sample memory during the retention interval.     

Natural rates of teacher approval and disapproval in grade-7 classrooms

The natural rates of teacher verbal approval and disapproval in ten grade-seven classrooms were determined and compared with those described by White (1975). Although there were differences in the observation techniques used and the behavioral, cultural, and ethnic groups sampled, the results were similar. The majority of the teachers displayed individual rates of disapproval that were higher than their individual approval rates. The correlations between levels of on-task behavior and approval and disapproval rates were low. The issues raised by these findings are discussed in terms of directions for further research.