Three-dimensional plotting of neuronal population response patterns

A computer technique is described for generating threedimensional plots of the distribution of spike activity in neuronal populations. Data obtained from single neurons in the sensorimotor cerebral cortex of cats are used to plot spike density with respect to depth in the cortex and time following a cutaneous stimulus. The computer programs include a masking (hidden line) subroutine and produce a cross-hatched plot showing the rise and fall of neuronal activity in both space and time. By manipulation of the data matrix and by axis rotations, the plot can be viewed from any desired perspective. This method constitutes a powerful technique for analyzing the spatio-temporal response patterns of neuronal populations. The significance of neuronal population responses for encoding stimulus information and predicting behavior is discussed. Note: Details concerning the computer programs developed for this plotting technique may be obtained from the Division of Systems and Computer Services, Medical College of Georgia, Augusta, GA 30901.     

Search for somatic 22q11.2 deletions in patients with conotruncal heart defects

A 46,XYq 8-year-old male was referred for microcephaly, growth, and mental retardation, hypotonia, genital hypoplasia, and dysmorphisms. FISH analysis showed that the rearranged Y chromosome originated from an unbalanced translocation of Xq27.3-qter onto the deleted Yq11.22. Analysis of reported patients with disomy of region distal to Xq26 suggests that this rare anomaly, associated with failure to dosage compensate X-linked genes that are normally inactivated, when present in two copies, is causing a quite distinct phenotype. This imbalance is the aberrant by product of the recombinogenic pairing of the distal pseudoautosomal Xq-Yq region at male meiosis.     

Visual acuity in the water maze: sensitivity to muscarinic receptor blockade in rats and mice

A visual acuity task performed in the water maze in rats [Behav. Brain Res. 119 (2001) 77] was used to reveal the sensitivity of the visual system to muscarinic receptor blockade. Intraperitoneal injection of 0.2 mg/kg scopolamine had no effect, but 2 mg/kg severely compromised visual acuity, but did not affect the swim strategy to solve the task. Spatial learning in a reference memory version of the water maze, however, was impaired by 0.2 mg/kg scopolamine. It was also confirmed that the same visual acuity task is applicable to C57BL6/J mice. The visual deficit induced by 2 mg/kg scopolamine was less severe compared to rats, possibly due to a change in swim strategy in the drug condition. The effect of scopolamine on spatial reference memory in mice was not tested in this study. These data suggest that it may be possible to dissociate drug-induced effects on memory from changes in sensory perception.     

Image quality of the temporal bone window examined by transcranial Doppler sonography and correlation with postmortem computed tomography measurements

BACKGROUND AND PURPOSE: The major limitation of native transcranial colour-coded duplex sonography (TCCS) in older stroke patients is the relatively frequent occurrence of an insufficient temporal window. Our goal was to investigate the relationship between the in vivo Doppler ultrasound image quality of the temporal bone, and computed tomography (CT)-determined thickness, density, and homogeneity of cadaver temporal bone. METHODS: Thirty-three moribund neurological patients who eventually died were examined by TCCS using the transtemporal approach. The sonographer categorized the quality of the TCCS image (excellent, intermediate, and poor). During autopsy, a rectangular sample of the temporal squama was removed, which corresponded to the area of the in vivo acoustic window. The thickness of the whole temporal bone, cortical, and cancellous (= diploe) bone as well as the density and homogeneity were determined by high-resolution CT. RESULTS: Thirty-seven temporal bones were obtained. The quality of the acoustic window was classified as excellent in 13, intermediate in 6 and poor in 18 cases. A significant correlation between the complete bone thickness, as well as between the absolute thickness of the diploe and the quality of the acoustic window was found: the thinner the bone/diploe, the better the colour Doppler signal. The thickness of the cortical plates and the homogeneity of the bones were identical in the three image quality categories. CONCLUSION: The transtemporal TCCS image quality depends mainly on the thickness of the cancellous component of the temporal bone.     

Suicide and general elections in Austria: do preceding regional suicide rate differentials foreshadow subsequent voting behavior swings?

BACKGROUND: Suicide-epidemiological research on short-term effects of elections on national/regional suicide and parasuicide incidence has yielded contradictory evidence. Reversing the cause-effect relationship of this line of research we investigated whether preceding regional suicide rates are related to subsequent election results. METHODS: For Austria's 121 districts, we regressed averaged standardized suicide rates for the preceding period (1988-1994) on political parties' subsequent electoral gains/losses (1999-to-1995) while controlling for a set of 12 domain-relevant psychosocial/economic indices. RESULTS: Stepwise weighted multiple regression led to a significant model. The 1999-to-1995 electoral gains/losses of two opposition parties, together with the population variation caused by migration balance and by births/deaths balance, accounted for a substantial part (30%) of the variability in preceding district-level suicide rates. Various other social indices failed to contribute further substantial increments to this model. CONCLUSIONS: This finding suggests that variations in preceding regional suicide incidence might be mirrored in subsequent changes in voting behavior. A speculative post hoc explanation for the finding is offered: on a community level, suicide's aftermath might produce socially and politically alienated survivors of suicide who co-shape swings towards opposition parties in subsequent general elections. The finding calls for more research on suicide's long-term aftermath. LIMITATIONS: Within-country replicability and cross-national generalizability await further investigation. At present, the factor/mechanism accounting for this finding is neither well-established nor has been directly tested.     

Successful birth after laser assisted immobilization of spermatozoa before intracytoplasmic injection

OBJECTIVE: To describe the first ICSI pregnancy achieved with sperm that were immobilized by using a noncontact diode laser. DESIGN: Case report. SETTING: Fertility center. PATIENT(S): A 36-year-old woman who had had primary infertility for 9 years. INTERVENTION(S): Sperm immobilization by using a 1.48-microm wavelength diode laser and subsequent ICSI. MAIN OUTCOME MEASURE(S): Fertilization and cleavage rates and pregnancy. RESULT(S): Transfer of two embryos with minor fragmentation led to a single pregnancy. The patient delivered a healthy baby in week 38 of gestation. CONCLUSION(S): Use of a noncontact diode laser for sperm immobilization may be a useful alternative to the conventional mechanical approach.     

Long-term study of chronic oral aluminum exposure and spatial working memory in rats

The authors report an effort to advance animal models that mimic the cognitive decline of Alzheimer's disease. Rats were trained and repeatedly tested in a spatial delayed matching-to-position paradigm in the water maze, with the location of the submerged platform changing between, but not within, days. After Trial 1 (random search) and intertrial intervals of 30 s or 1 hr, memory was tested in Trial 2. Young rats quickly acquired this task and were repeatedly tested after different intervals over 7 months, with a slight increase in performance toward the end of testing, but no difference in latencies between delays. Oral long-term treatment of 1 group with 0.1% aluminum caused no delay-dependent working memory deficit. This testing protocol may enable between- and within-subject long-term assessment of spatial working memory before and after drug treatment and may prove useful in animal models of progressive cognitive decline.