Right hemisphere control of visuospatial attention: line-bisection judgments evaluated with high-density electrical mapping and source analysis

The "line-bisection" task has proven an especially useful clinical tool for assessment of spatial neglect syndrome in neurological patients. Here, we investigated the neural processes involved in performing this task by recording high-density event-related potentials from 128 scalp electrodes in normal observers. We characterized a robust net negative potential from 170-400 ms poststimulus presentation that correlates with line-bisection judgments. Topographic mapping shows three distinct phases to this negativity. The first phase (approximately 170-190 ms) has a scalp distribution exclusively over the right parieto-occipital and lateral occipital scalp, consistent with generators in the region of the right temporo-parietal junction and right lateral occipital cortices. The second phase (approximately 190-240 ms) sees the emergence of a second negative focus over the right central parietal scalp, consistent with subsequent involvement of right superior parietal cortices. In the third phase (approximately 240-400 ms), the topography becomes dominated by this right central parietal negativity. Inverse source modeling confirmed that right hemisphere lateral occipital, inferior parietal, and superior parietal regions were the likeliest generators of the bulk of the activity associated with this effect. The line stimuli were also presented at three contrast levels (3, 25, and 100%) in order to manipulate both the latency of stimulus processing and the relative contributions from magnocellular and parvocellular inputs. Through this manipulation, we show that the line-bisection effect systematically tracks/follows the latency of the N1 component, which is considered a temporal marker for object processing in the ventral visual stream. This pattern of effects suggests that this task invokes an allocentric (object-based) form of visuospatial attention. Further, at 3% contrast, the line-bisection effect was equivalent to the effects seen at higher contrast levels, suggesting that parvocellular inputs are not necessary for successful performance of this task.     

Diagnostic value of a psychological test in cases of suspected child abuse

The use of the Bene-Anthony Family Relations Test is described and illustrated by three examples of child abuse. This test should be considered in the investigation of definite or suspected cases of abuse and as part of the preparation of court evidence.     

Complex and simple coronary artery stenoses: a new way to interpret coronary angiograms based on morphologic features of lesions

For many years, atherosclerotic coronary artery lesions have been described by angiographers only in terms of location and degree of narrowing. However, it has become apparent that coronary stenoses generally have distinct morphologic features that can be recognized at angiography and that allow them to be classified as either "simple" or "complex" plaques. Complex plaques are those characterized by ulcerated or ruptured surfaces, subintimal hemorrhage, superimposed partially occluding thrombi, recanalized thrombi, or some combination. Pathologic studies have shown a very high frequency of these lesions at sites of total thrombotic occlusion of coronary arteries. Clinical and angiographic studies have demonstrated a high frequency of such lesions in living patients with both unstable angina and acute myocardial infarction. The presence of complex stenoses has also been found to increase the risk of future myocardial infarction. Plaque morphology thus appears to significantly affect the prognosis of patients with coronary disease and should be carefully evaluated in interpretation of all coronary angiograms.     

The relationship between visual acuity and functioning and well-being among diabetics

Given the enormous recent interest in functional capabilities related to vision, the goal of this study was to examine the relationship of standard clinicial measures of vision (e.g. Snellen acuity) to functioning and well-being. The association between Snellen visual acuity, Amsler grid distortion and presence of diabetic retinopathy with self-reported functioning and well-being (SF-36) were examined in a sample of 327 diabetics from the Medical Outcomes Study (MOS). There was little or no correlation between Snellen visual acuity, Amsler grid distortion or diabetic retinopathy and functioning and well-being (i.e. SF-36 scales). Maximum product-moment correlation was 0.15 with worst eye visual aculty, 0.13 with best eye visual acuity, 0.08 with presence of retinopathy, and 0.10 with Amsler grid distortion. Analysis of variance revealed that visual acuity (both best and worst eye) was statistically related only to the physical function scale; no other exam measure was related to any other SF-36 scale score. Snellen visual acuity, Amsler distortion and diabetic retinopathy correlate weakly with patient self-reported functioning and well-being. Thus, the information provided by functioning and well-being measures is complementary to that of standard clinical measures of visual ability.     

Reversal of phencyclidine-induced prepulse inhibition deficits by clozapine in monkeys

Rationale Prepulse inhibition (PPI) of the acoustic startle reflex is a measure of sensorimotor gating, which occurs across species and is deficient in severe neuropsychiatric disorders such as schizophrenia. In monkeys, as in rodents, phencyclidine (PCP) induces schizophrenia-like deficits in PPI. In rodents, in general, typical antipsychotics (e.g. haloperidol) reverse PPI deficits induced by dopamine (DA) agonists (e.g. apomorphine), but not those induced by N-methyl-d-aspartate (NMDA) receptor antagonists [e.g. phencyclidine (PCP)], whereas atypical antipsychotics (e.g. clozapine) reverse PPI deficits induced by DA agonists and NMDA antagonists. However, some discrepancies exist with some compounds and strains of rodents.Objectives This study investigated whether a typical (haloperidol, 0.035 mg/kg) and an atypical (clozapine, 2.5 mg/kg) antipsychotic could be distinguished in their ability to reverse PCP-induced deficits in PPI in eight monkeys (Cebus apella).Methods First, haloperidol dose was determined by its ability to attenuate apomorphine-induced deficits in PPI. Then, haloperidol and clozapine were tested in eight monkeys with PCP-induced deficits of PPI. Experimental parameters were similar to standard human PPI procedures, with 115 dB white noise startle pulses, either alone or preceded by 120 ms with a prepulse 16 dB above the 70 dB background noise.Results Clozapine reversed PCP-induced PPI deficits. In contrast, haloperidol did not significantly attenuate PCP-induced PPI deficits even at doses that significantly attenuated apomorphine effects.Conclusions In this primate model, clozapine was distinguishable from haloperidol by its ability to attenuate PCP-induced deficits in PPI. The results provide further evidence that PPI in nonhuman primates may provide an important animal model for the development of novel anti-schizophrenia medications.     

Risk of retinal detachment following cataract extraction: results from the International Cataract Surgery Outcomes Study.

AIMS: To estimate the risk of retinal detachment (RD) following cataract extraction in Denmark, and to compare the risk with that following cataract extraction in the USA, and with that in a sample of Danish patients who did not have ocular surgery. METHODS: A sample was created from the administrative Danish Hospital Register and included 19,252 patients who underwent first eye cataract surgery between 1985 and 1987, and who were 50 years of age or older. The patients were then followed for 4-6 years using the register data. The design and definition of events were identical to the US National Study of Cataract Outcomes. RESULTS: In Denmark a 4 year cumulative risk of hospitalisation for RD of 0.93% (95% confidence interval (CI) 0.71-1.16) was observed following an extracapsular cataract extraction with a lens implant. A similar cumulative risk of RD was reported from the US study. Thus, no difference in outcomes concerning risk of RD was shown between Denmark and the USA. In a multivariate analysis younger age, male sex, and intracapsular cataract extraction were all associated with higher risk of postoperative RD. A reference group of 7636 people not undergoing any ocular surgery was created and the incidence of RD in this group was calculated. During the sixth year following cataract surgery, the incidence of RD in the cataract group was still 7.5 (95% CI 1.6-22.0) times higher than that observed in the reference group.     

The role of excitatory amino acids in neuropsychiatric illness

Over the past several years, research has demonstrated that the excitatory amino acids serve as the major excitatory neurotransmitters in cerebral cortex and hippocampus. Neurons that contain excitatory amino acids play crucial roles in neuropsychological functioning, learning, and memory. In addition, these neurons exert descending control over subcortical structures that is behaviorally antagonistic to the effects mediated by the ascending dopaminergic system. Disturbances of excitatory amino acid systems may contribute to the pathogenesis of schizophrenia and to other neuropsychiatric syndromes associated with delirium or dementia.