Testing the scanning effect of a range of orientations by visual cortex neurons of the cat

The preservation of the effect of dynamic scanning of a part of the orientation diapason during development of neuron responses in the primary visual cortex of cat was examined after equalization of their latencies and after estimation of only highly significant fragments of their reactions. It was found that this effect was preserved in 13 neurons out of 17 examined ones: it remained invariable in 7 units of this group and was modified due to a shift of the scanning beginning along the diapason of orientations, to an increase of scanning diapason or to a change of scanning direction. The stabilization of the orientational tuning occurred only in 4 cells after equalization of latencies. The obtained results confirm that the dynamic changes of orientation tuning in the majority of visual cortex neurons are connected with reorganization of the time pattern of the reaction, as suggested by the hypothesis of the spatial-temporal orientation coding in the visual system.     

Tuning of striate neurons to cross-shaped figures in conditions of local blockade of intracortical inhibition

The recently observed selective sensitivity to cross-shaped and angular figures was studied in 85 primary visual cortex (field 17) neurons in cats before and after local blockade of GABA_A ergic inhibition by microiontophoretic application of the GABA antagonist bicuculline. Two opposite effects were seen: half of the neurons studied showed decreases or complete loss of sensitivity to crosses, and a third of the cells showed increases or the appearance of sensitivity to crosses. These data provide evidence for significant roles for intracortical inhibition in providing sensitivity to crosses and intersecting lines in two types of visual cortex neurons, the effects on these two types of neuron being opposite. Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti, Vol. 49, No. 2, pp. 271–278, March–April, 1999.     

Mutational analysis of the SOX9 gene in campomelic dysplasia and autosomal sex reversal: lack of genotype/phenotype correlations

It has previously been shown that, in the heterozygous state, mutations in the SOX9 gene cause campomelic dysplasia (CD) and the often associated autosomal XY sex reversal. In 12 CD patients, 10 novel mutations and one recurrent mutation were characterized in one SOX9 allele each, and in one case, no mutation was found. Four missense mutations are all located within the high mobility group (HMG) domain. They either reduce or abolish the DNA-binding ability of the mutant SOX9 proteins. Among the five nonsense and three frameshift mutations identified, two leave the C-terminal transactivation (TA) domain encompassing residues 402-509 of SOX9 partly or almost completely intact. When tested in cell transfection experiments, the recurrent nonsense mutation Y440X, found in two patients who survived for four and more than 9 years, respectively, exhibits some residual transactivation ability. In contrast, a frameshift mutation extending the protein by 70 residues at codon 507, found in a patient who died shortly after birth, showed no transactivation. This is apparently due to instability of the mutant SOX9 protein as demonstrated by Western blotting. Amino acid substitutions and nonsense mutations are found in patients with and without XY sex reversal, indicating that sex reversal in CD is subject to variable penetrance. Finally, none of 18 female patients with XY gonadal dysgenesis (Swyer syndrome) showed an altered SOX9 banding pattern in SSCP assays, providing evidence that SOX9 mutations do not usually result in XY sex reversal without skeletal malformations.      

"Timers" and "scanners" among orientation detectors of the visual cortex in the cat

Acute experiments on immobilized cats were carried out to check the suggestion that a special class of neurons ("timers") which do not change time properties of responses with variations in light bar orientation exists in the visual cortex. Previously neurons of the visual cortex with a dynamic shift of preferable orientation ("scanners") were revealed. Among 76 neurons 27 (36%) showed different properties: stability of latencies in the orientation range, shorter initial and peak latencies, duration and time of the discharge frequency increase, wider orientational tuning and worse relations between magnitudes of responses to preferred and nonpreferred stimuli. They were considered as representatives of the suggested "timers".     

Search for an optimal therapy of patients with atrial fibrillation (results of many years of comparison of three treatment strategies).

Patients with nonrheumatic atrial fibrillation (n=465, mean age 59.4+/-3.8 years) received controlled therapy for 7.4+/-1.6 years. Group 1 comprised 306 patients with paroxysmal and persistent atrial fibrillation who after restoration of sinus rhythm received antiarrhythmic therapy aimed at prevention of recurrences and repetitive cardioversions. Group 2 consisted of 67 similar patients who did not receive continuous antiarrhythmic therapy. Therapy of patients with persistent atrial fibrillation (group 3, n=92) included heart rate slowing drugs and anticoagulants. Group 1 was characterized by lowest rate of complications and all cause mortality, and best quality of life. There were more nonfatal strokes in group 2. All cause mortality in group 2 was 15% (p<0.05). Highest rate of nonfatal strokes, and deaths due to chronic heart failure was observed in group 3. All cause mortality in this group was 22.8% (p<0.001 vs group 1).     

Psychiatric morbidity in stroke patients attending a neurology clinic in Nigeria

Back ground

Stroke produces a wide range of mental and emotional disorders. Neuropsychiatric complications associated with stroke may have negative effects on the social functioning, overall quality of life and the recovery of motor functioning of stroke survivors.

Objective

To determine the prevalence and nature of psychiatric morbidity among stroke patients attending neurology outpatient clinic of the University of Ilorin Teaching Hospital (UITH), Ilorin-Nigeria.

Methods

All patients with stroke aged 18 years and above at an outpatient neurology clinic in Ilorin, Nigeria were assessed for mental and emotional disorders using the Schedule for Clinical Assessment in Neuropsychiatry (SCAN) over one year (March 2009 to February 2010).

Results

Overall prevalence of psychiatric morbidity was 36.0% (30/83) among 83 patients who constituted the study population. Specific diagnoses recorded were depression (19.2%), generalised anxiety disorder (9.6%), harmful alcohol use (2.4%); dementia, somatoform disorder, phobia and delusional disorder each had a prevalence of 1.2%. Clinical and sociodemographic variables were not significantly associated with psychiatric morbidity.

Conclusion

Psychiatric disorders are often associated with stroke. Identifying and treating stroke patients with these psychiatric co-morbidities could thus help to improve the overall quality of life of these patients.