[Functional magnetic resonance and the cerebral cortex. 1: Group analysis]. / Resonancia magnética funcional y el córtex motor. I: análisis de grupo.

INTRODUCTION: Various strategies are used to increase the sensitivity to activation in functional magnetic resonance (RMf) with bold contrast, including raised magnetic fields and group analysis. Although very important, study of the behaviour of the signal in a group (normal pattern) remains a problem in RMf. OBJECTIVES: To study the behaviour of the signal in response to the motor paradigm using RMf with bold contrast at 3T in a group, by random effect analysis. RESULTS: The areas of most solid activation were the somatomotor area, the contralateral SMA and ipsilateral cerebellar area. Other areas showed greater variability (the number of persons who activated them and their localization). Analysis of the group showed close correlation between individuals both in the areas mentioned and in the basal ganglia, and to a lesser extent in ipsilateral premotor and somatomotor areas. There was wide variability in prefrontal, frontal, dorsolateral and parietal areas. CONCLUSIONS: There is some variation in activation (number and position of the activated areas). SM, SMA and cerebellum have a high degree of inter individual anatomofunctional concordance. Activity in the basal ganglia, in spite of high inter individual anatomofunctional correlation, may not be easy to observe. Some areas are activated in certain persons but not on analysis of the group. This shows inter individual functional and/or anatomical variability. Such variation in activation should be remembered in subsequent analysis. Group analysis is useful for showing collective patterns which determine the most consistent areas on which to base subsequent individual analysis.

[Functional magnetic resonance and the motor cortex II: measurement of activity]. / Resonancia magnética funcional y el córtex motor. II. Cuantificación de la activación.

INTRODUCTION: Functional magnetic resonance (fMR) with BOLD contrast has been shown to be a useful tool for clinical investigation. It is still uncertain which is the best way to establish the measures of activation for subsequent comparisons and their physiological significance. OBJECTIVE: To explore the activation expressed as a function of different parameters. PATIENTS AND METHODS: We did fMR with BOLD contrast at 3T and a motor paradigm in 14 healthy persons. The activation was expressed as the number of voxels activated within each area; their percentage in relation to the total number of voxels activated; z value; laterality index, speed and degree of temporal variation in the signal of these voxels. RESULTS: Somatomotor area (SM) activated 121% more voxels than supplementary motor area (SMA), but their variation expressed with their standard variation was very large. The percentage of voxels activated was 163.6% greater in SM than in SMA. The laterality index increased at the expense of activation outside SM. The variation of the two relative measurements was less than the total number of voxels. The z value did not correlate with the degree of activity. The time course of the SMA signal was slightly different to SM. CONCLUSIONS: Very high field fMR is very sensitive to changes in signal. The number of voxels activated varies considerably, so its use as a measurement of activity should be limited. Relative value, such as the index of laterality of the percentage of voxels may show less variability. The centre of mass and z value are stable figures but the physiological significance of the latter is not clear. The study of the temporal variation of the signal seems to be a potentially useful parameter with a certain degree of physiological significance, although better understanding and further analysis is necessary.

Resonancia magnética funcional y el córtex motor. II. Cuantificación de la activación / Functional magnetic resonance and the motor cortex. II. Measurement of activity

Introducción. La resonancia magnética funcional (RMf) con contraste BOLD se está consolidando como una herramienta útil en la investigación clínica. Está por determinar cuál es la mejor forma de establecer las medidas de la activación para posteriores comparaciones, así como cuál es la significación fisiológica de las mismas. Objetivos. Explorar la activación expresada en función de varios parámetros. Sujetos y métodos. Realizamos RMf con contraste BOLD a 3 T y paradigma motor en 14 sujetos sanos. La activación se expresó como número de voxels activados dentro de cada área, porcentaje de los mismos en relación con el número total de voxels activados, valor z, índice de lateralidad, y velocidad y cuantía de la variación temporal de la señal en dichos voxels. Resultados. El área somatomotora (SM) activó un 121 por ciento más voxels que el área motora suplementaria (SMA), pero su variación expresada con su desviación estándar fue muy grande. El porcentaje de voxels activados fue un 163,6 por ciento superior en SM que en SMA. El índice de lateralidad aumenta a expensas de la activación fuera del SM. La variación de ambas medidas relativas fue menor que con el número total de voxels. El valor z no fue correlacionable con el grado de actividad. El curso temporal de la señal en SMA fue ligeramente diferente a SM. Conclusiones. La RMf de muy alto campo es muy sensible a los cambios de señal. El número de voxels activados es un valor muy variable, por lo que su uso como medida de activación debe ser limitado. Valores relativos como el índice de lateralidad o el porcentaje de voxels pueden ofrecer menor variabilidad. El centro de masas y el valor z son medidas estables pero el significado fisiológico del segundo es incierto. El estudio de la variación temporal de la señal se presenta como un parámetro potencialmente útil y con cierto significado fisiológico, aunque necesita de una mejor comprensión y análisis (AU)

Pineal gland in rats with 7,12-dimethylbenz(a)anthracene-induced mammary tumors subjected to manipulations known as enhancers of pineal actions.

The ultrastructure of pinealocytes was studied in rats with 7,12-dimethylbenz(a)anthracene-induced mammary tumors which were subjected to experimental manipulations known as enhancers of pineal actions (anosmia, underfeeding or cold exposure). In these animals we found: (I)--more nuclei with deep nuclear invaginations; (II)--a large number of cytoplasmic organelles, including lipid droplets, myeloid bodies, synaptic ribbons and lysosomes; (III)--numerous degenerative changes. In general, we found an increase in structural features related to pineal photoneuroendocrine activity. Our results indicate that pineal-dependent inhibition of neoplastic growth induced by these experimental manipulations, previously reported, can be mediated through an increase in pineal metabolic activity.

[Numerical variation in synaptic ribbons of rat pinealocytes under magnetic storm conditions and on calm days]. / Veränderungen der Anzahl synaptischer Bänder in der Pinealdrüse der Ratte an geomagnetischen Ruhetagen und Gewittertagen.

Based on the hypothesis of the magnetoreceptor function of the pineal gland, a comparative study has been made, with electronic microscopy, of the numerical variations of the synaptic ribbons of the pinealocytes (indicating the cellular metabolic activity) of the groups of rats, under magnetic storm conditions and in calm days. In this quantitative study it was established that the incidence of synaptic ribbons per each 20,000 microns 2 of pineal tissue was smaller in the group of animals sacrificed during geomagnetic storms, as compared with the other group of animals sacrificed in calm periods (P less than 0.001). It was suggested that the synaptic ribbons may be morphological indicators of the pineal activity, with respect to the variations of the geomagnetic field.

[Synaptic ribbons in pinealocytes of olfactory bulbectomized rats under experimental conditions]. / Synaptische Bänder in den Pinealocyten bulbektomierter Ratten unter experimentellen Bedingungen.

In previous studies it has been suggested that the increase in the number of synaptic ribbons is parallel to the melatonin forming activity of the pineal gland. The presence of synaptic ribbons in the pinealocytes of rats subjected to experimental manipulations known as enhancers of pineal actions (blindness, blindness + olfactory bulbectomy, blindness + underfeeding and blindness + cold exposure) has been studied. We found a significantly lower number of synaptic ribbons in the pinealocytes of control rats as compared with rats subjected to enhanced pineal actions. Since the latter showed a pineal-dependent gonadal atrophy and low serum estradiol levels, a direct relationship between the number of synaptic ribbons and the functional status of the pineal gland may be established. Thus, our results suggest that the number of synaptic ribbons might be an indicator of pineal activity.

Myeloid bodies associated with lipid droplets in pinealocytes of blind, blind-bulbectomized, blind-underfed or blind cold-exposed rats.

The ultrastructure of pinealocytes was studied in rats subjected to manipulations known as enhancers of pineal actions: blindness (B), blindness + olfactory bulbectomy (BObx), blindness + underfeeding (BU), blindness + cold exposure (BC). A large number of myeloid bodies (MBs) were found especially in the light pinealocytes of BObx, BU and BC rats but not in intact controls. These MBs were, in most cases, associated with lipid droplets. The presence of a large number of MBs in rats in which pineal-dependent gonadal impairment has been demonstrated, strongly supports the hypothesis that MBs play a role in pineal photoneuroendocrine activity.

Neuroglia of the optic tectum in the Bufo bufo (Amphibian Anura), first trials.

Only one predominant type of glial cell can be recognized in the Bufo bufo toad's optic tectum, obtained sagitally cut in 40 microns thick sections and stained with sublimate-gold CAJAL'S method. This basically elementary cell type is represented by ependymal gliocytes (Horstmann's tanycytes) with long processes in small parallel bundles disposed radially, extending from the ventricular surface to the sub-pial surface forming terminal end-feet thickenings. These processes can lose themselves freely too or split up before ending in the neuropil and they can even reach the blood vessels, contacting with them. In this work we present these first trials as an anatomical basis for further complementary histochemical, electron microscope and experimental studies.

Ultrastructure of the pineal cells of the homing pigeon Columba livia and magnetic fields (first trials).

The homing pigeon Columba livia was exposed to uniform 60 Hz AC magnetic fields, generated by Helmholtz coils with an intensity of 200 mG for 48 hrs. The microscopic studies performed revealed that only some of the pineal cells (between 20 and 30%) seemed to respond to the magnetic stimulation, and showed different ultrastructural morphological changes; the most striking effect was an apparent increase of apocrine secretion to the luminal spaces in the epiphyseal epithelium of this avian species.