Settembre 2007 - Volume XXVI - numero 7
Focus
Giornalista scientifico
Key words: Brodmann’s areas, Migration, Gyration, Synaptogenesis, Neuropsychiatric, Epilepsy, Dyslexia, Autism
An elementary panorama on the functioning and development of the brain cortex in the embryo, foetus and child is sketched out. The neurons of the cortex are organised in functional columns, lined in six strata, each of them having vertical connections in the column itself, and horizontal connections with the far areas of the cerebral grey matter. The cortex is divided into areas, differentiated according to the microstructure (Brodmann’s areas) and to their functions (sensory, motor, associative and mixed areas). However, this gross subdivision does not explain the complexity of superior cerebral functions. The construction of the cortex takes place on the layout of a general plan organised by architect genes and under the action of numerous molecules having local effect on adhesion, recall, inhibition and proliferative stimuli. It is during these phases that migration, gyration and synaptogenesis defects, which cause neuropsychiatric pathologies such as epilepsy, dyslexia, and autism occur.
Vuoi citare questo contributo?
Focus
Key words: Brodmann’s areas, Migration, Gyration, Synaptogenesis, Neuropsychiatric, Epilepsy, Dyslexia, Autism
An elementary panorama on the functioning and development of the brain cortex in the embryo, foetus and child is sketched out. The neurons of the cortex are organised in functional columns, lined in six strata, each of them having vertical connections in the column itself, and horizontal connections with the far areas of the cerebral grey matter. The cortex is divided into areas, differentiated according to the microstructure (Brodmann’s areas) and to their functions (sensory, motor, associative and mixed areas). However, this gross subdivision does not explain the complexity of superior cerebral functions. The construction of the cortex takes place on the layout of a general plan organised by architect genes and under the action of numerous molecules having local effect on adhesion, recall, inhibition and proliferative stimuli. It is during these phases that migration, gyration and synaptogenesis defects, which cause neuropsychiatric pathologies such as epilepsy, dyslexia, and autism occur.
Vuoi citare questo contributo?
Focus
Professore Emerito, Dipartimento della Riproduzione e dello Sviluppo, Università di Trieste
Key words: Neurophysiology, Developmental neuropathology, Myelinisation, Wernicke’s area, Gilles de la Tourette syndrome
he development of the cerebral cortex, mainly linked to gyration, especially in the prefrontal and visual areas, is the most distinctive phenomenon of the Homo species. From birth onwards, brain growth is mainly due to the numeric increase in the glia cells, whose ratio with the neurons goes from 1.7 at birth to 10 when the development is over, and to the growth and myelinisation of dendrites and axons (white substance). The maturation of each area occurs through an increase in the local ratio between white and grey substance. Numerous little differences distinguish male from female brain, being the male brain characterized by a major hemispheric asymmetry, minor diameter of the corpus callosum; major size of the amygdala, minor dimensions of the hippocampus; major dimension of the striatum and minor dimensions of the caudatum. At least some of these differences are due to the effect of testosterone, which is probably also responsible for the major incidence in males of a few disorders: hyperactivity (disorder of the right pre-frontal striated area, inhibiting system at the level of the base ganglions and cerebellum), dyslexia (Wernicke’s area) and autism (microstructural anomalies in rhomebencephalon, mesencephalon and in cerebellum, but also in the hemispheric cortex). Morpho-functional alterations can be observed in Gilles de la Tourette syndrome and in the compulsive obsessive disorder. Dorsolateral-frontal and prefrontal perfusion and metabolic defects, as well as an increase in the size of the hypophysis, can be observed in depression. A similar increase occurs also in nervous anorexia, accompanied by a (reversible) decrease in the cerebral substance thickness. Very small hyperdense focuses can be seen in the tension/tiredness syndrome.
Vuoi citare questo contributo?
Focus
Già Direttore dell’Istituto di Radiologia dell’Università di Trieste
Key words: Nuclear Magnetic Resonance or NMR, Positron Emission Tomography or PET, Single Photon Emission Tomography or SPECT, Magnetic Resonance Spectrography or MRS
maging techniques such as Nuclear Magnetic Resonance or NMR, Positron Emission Tomography or PET, Single Photon Emission Tomography or SPECT and Magnetic Resonance Spectrography or MRS have contributed to understand the mechanisms of the different forms of perception, action, thinking, feeling, as well as of affective disorders. Each technique has its specificity and enables to “see” each phenomenon from different points of view. As a whole, these techniques give us some space-temporal indications: the type of structures, cell groups and also what and when single neurons activate, in which sequence during the performing of a task, under the action of a specific stimulus or when resting. Deviations from normality registered in standard conditions help us understand the site and the quality of the neuro-functional substrata involved in some disorders of the psychic sphere. In the present article the different investigation techniques and their applicative specificity are illustrated.
Vuoi citare questo contributo?
