Amygdala-hippocampal volume and verbal memory in first-degree relatives of schizophrenic patients.

Verbal memory deficits have been related to reduced volume of medial temporal structures in several neurological and psychiatric populations, including schizophrenic patients. Impairments in verbal memory have been proposed to be a marker of risk for schizophrenia. Recently, relatives of schizophrenic patients have been reported to have reduced volume of the amygdala-hippocampal complex. In this study, we evaluate the possibility that amygdala-hippocampal volume reductions may constitute one neural substrate of verbal memory deficits in first-degree relatives. Subjects were 20 healthy first-degree relatives of schizophrenic patients and 14 demographically similar controls. Verbal memory was assessed with the Logical Memory Test. Subjects were scanned with high-resolution MRI and the images were transformed into Talairach space. Volumes of interest were amygdala-anterior hippocampus and posterior hippocampus. Relatives of schizophrenic patients had intact immediate verbal memory but significantly poorer delayed verbal memory than controls. Relatives also had significantly reduced amygdala-anterior hippocampus volumes. Across all subjects, delayed verbal memory was significantly correlated with amygdala-anterior hippocampus volume. The magnitude of the correlation did not differ between the groups. These data provide an empirical link between memory performance and volumetric abnormalities in the amygdala-hippocampal complex in the relatives of schizophrenic patients.

Are xenotransplantation safeguards legally viable?

Scientists agree on the need for robust public health safeguards to accompany the imminent introduction of xenotransplantation--clinical transplantation of animal tissue into humans. To protect society in the event of emerging infectious diseases, governments must devise a legally effective means of ensuring compliance with such safeguards. Neither consent law, the law of contracts, nor existing public health legislation can adequately enforce such compliance. Consent law serves as a mechanism of communicating the momentary waiver of legal rights, not as a durable enforcement doctrine. Because it would be essential for recipients personally to comply with public safety measures, the law of contracts would also be unable to compel compliance. Existing public health legislation would also likely be ineffective because it would need to be substantially amended to incorporate the heightened powers necessary for the periodic examination of asymptomatic xenotransplant recipients. Xenotransplantation-specific legislation would be a legally effective means of enforcing public health safeguards since it could require conforming behaviors and could impose monetary fines on those recipients who, having benefited from life-saving intervention, fail to comply. This Article argues that legislation implementing a post-xenotransplantation surveillance system should withstand constitutional scrutiny because it would not be discriminatory and because, although it would violate fundamental rights of recipients, such violations would be justified under existing constitutional doctrines.

Functional neuroanatomy of smooth pursuit and predictive saccades.

We used PET to study differences in cerebral blood flow (CBF) in smooth pursuit, predictive saccades and fixation. Eye movements were monitored in the scanner. Compared with fixation, pursuit and predictive saccades activated a network of highly similar areas, including frontal eye fields, supplementary eye fields, V5 and medial cuneus. Our findings are consistent with non-human primate studies that suggest that pursuit and saccades are controlled by similar and adjacent neural areas. Pursuit was associated with greater activation of caudate than saccades, suggesting a role for basal ganglia in pursuit that is consistent with studies of neurological populations. Saccades were associated with greater activation of cerebellum and frontal eye fields. A frontal-cerebellar loop may be important in coordinating the preparation and timing of saccades in predictive tracking.

Genetics, parenting, and children's rights in the twenty-first century.

Not only do genetic traits sometimes translate into physical and mental illnesses, they may also manifest themselves as tendencies towards certain behaviours. This discovery has led to the misinterpretation and misapplication of genetic information, and has been directed to unforeseen uses, from criminal defence to genetic racism. The issue is especially sensitive when deciding if and when parents should have access to the genetic information of their children. The author begins with an overview of the principles of behavioural genetics and types of behaviour currently under study. Next, the social and psychological risks associated with genetic testing are presented, along with guidelines necessary to distinguish between testing which is therapeutic and that which is non-therapeutic. The distinction is a crucial one, as the author proposes a therapeutic-benefit test, advocating testing only where an effective intervention is available. Finally, the author concludes that legislation is the more appropriate medium for defining the extent of parental rights once intervention is allowed rather than leaving physicians to decide on a case-by-case basis.

Neural correlates of eye tracking deficits in first-degree relatives of schizophrenic patients: a positron emission tomography study.

BACKGROUND: Schizophrenia is thought to arise from the interaction of genetically mediated and environmentally triggered abnormalities in brain function. Reduced frontal activation, reported in schizophrenic patients, may be one expression of genetic risk. The present study investigated whether frontal activation in relatives of schizophrenic patients would be related to eye tracking deficits (ETD), which are considered a behavioral marker of risk for schizophrenia. METHODS: Subjects were first-degree relatives of schizophrenic patients (n = 17) and controls (n = 11). Relatives were divided into those with normal and abnormal pursuit based on qualitative ratings. Subjects were scanned using positron emission tomography and the H(2)15O bolus subtraction technique while performing smooth pursuit and fixation. Brain areas more active in pursuit than fixation were identified in the 3 groups. Correlations were used to investigate the relationship between activation of pursuit regions and pursuit gain in the relatives. RESULTS: Controls significantly activated frontal eye fields (FEFs) and posterior areas, including the motion processing area, V5, and cuneus. The 2 groups of relatives activated the same posterior regions as controls, but differed from each other in activation of FEFs. Relatives with normal tracking activated right dorsal FEFs while relatives with ETD did not. Individual subtractions revealed that 90% of controls and 100% of the relatives with normal tracking activated FEFs during pursuit compared with 42% of relatives with ETD (P = .009). Pursuit gain was significantly and selectively associated with percent activation of right dorsal FEFs (r = 0.74). CONCLUSIONS: Subtle frontal dysfunction seems to be a pathophysiological substrate of ETD in relatives of schizophrenic patients, and may be one aspect of genetically mediated differences in brain function relevant to schizophrenia.

Xenotransplantation and public health: identifying the legal issues.

The debate over the acceptability of clinical trials for xenotransplantation has focussed primarily on analyses of: 1) the medical benefits that might accrue to individual patients in need of organ replacement therapy; 2) the risk of introducing new infectious disease(s) into the population; and 3) the ability of public safety measures to minimize that risk. It is now generally accepted that if we are to proceed with xenobiotechnology, sufficient public safety measures must first be adopted. Despite the growing consensus as to the indispensability of scientific safeguards, few authors have questioned the ability of current or novel legal frameworks to sustain and enforce such safeguards. A legal analysis of the public health concerns must be incorporated into the debate if we are to ensure a thorough and responsible decision-making process.