Search results for "Cerebral cortex"

Morphometric magnetic resonance imaging cortico-subcortical features in Parkinson's disease with mild cognitive impairment

2022

Background and purpose Parkinson's disease (PD) patients with cognitive impairment undergo progressive atrophy of several cortical and subcortical areas. The aim was to study the magnetic resonance imaging (MRI) morphometric features of PD patients with mild cognitive impairment (MCI). Methods Patients from the Parkinson's Disease Cognitive Impairment Study (PACOS) cohort with an available structural volumetric brain MRI and morphometric measurements of the midbrain and pons areas, middle cerebellar peduncle, superior cerebellar peduncle width and midbrain anteroposterior diameter (A-Pdiam) were included. MCI was diagnosed according to the Movement Disorder Society level II criteria. Additi…

Cortical Temperature Change: A Tool for Modulating Brain States?12

2016

Reduction in temperature depolarizes neurons by a partial closure of potassium channels but decreases the vesicle release probability within synapses. Compared with cooling, neuromodulators produce qualitatively similar effects on intrinsic neuronal properties and synapses in the cortex. We used this similarity of neuronal action in ketamine-xylazine-anesthetized mice and non-anesthetized mice to manipulate the thalamocortical activity. We recorded cortical electroencephalogram/local field potential (LFP) activity and intracellular activities from the somatosensory thalamus in control conditions, during cortical cooling and on rewarming. In the deeply anesthetized mice, moderate cortical co…

Postnatal neurogenesis in the medial cortex of the tropical lizard Tropidurus hispidus.

2004

Young, adult and presumed old specimens of the tropical lizard Tropidurus hispidus, living in an almost steady warm habitat, have been the subjects of a 5-bromodeoxiuridine immunocytochemical study to label proliferating brain cells. All animals showed abundant 5-bromodeoxiuridine-labeled nuclei in the ependyma of their telencephalic lateral ventricles, with these being especially abundant in the medial cortex ependyma. Surprisingly, adult animals displayed higher numbers of labeled nuclei when compared with those of young specimens. In a second experiment, in order to check the evolution of ependymal-labeled nuclei, adult specimens were allowed 4 h or 2, 4, 7, 15 or 30 days of survival aft…

Cellular and subcellular distribution of receptors in the entorhinal—hippocampal system: Morphologic and biochemical aspects

1993

Lissencephalic syndromes: brain and beyond

2009

Lissencephaly has been long maintained a malformation involving only the brain. Classic lissencephaly includes agyria and pachygyria and it is the most severe form of malformations derived from abnormal neuronal migration. It is defined as a smooth or nearly smooth cerebral surface with absence of normal sulci and gyria. It encompasses a group of syndromes which show many different clinical conditions. Four groups are actually distinguished: classic lissencephaly variants, other lissencephalies including forms with unknown pathogenesis, microlissencephaly spectrum and Cobblestone cortical malformations. Several genes and proteins are involved in this syndromic spectrum and each year new mol…

Long-spined polymorphic neurons of the medial cortex of lizards: a Golgi, Timm, and electron-microscopic study.

1988

The morphology, ultrastructure, and principal synaptic input of longspined neurons located in the inner plexiform layer of the medial cortex in three related species of lizards is described. Golgi impregnations have been used to define the external morphology of these neurons and their axonal trajectories. Their most striking characteristic is the presence of very long spines or “microdendrites” especially abundant on the distal dendritic segments. Axons have ascendent trajectories, pass through the cell layer, and ramify in the outer plexiform layer. Combined Golgi-electron microscopy as well as standard electron microscopy permitted the definition of the ultrastructure of these neurons. T…

Analysis of neuronal networks in the visual system of the cat using statistical signals--simple and complex cells. Part II.

1978

Superimposing additively a two-dimensional noise process to deterministic input signals (bars) the neurons of area 17 show a class-specific reaction for the task of signal extraction. Moving both parts of the signals simultaneously and varying the signal to noise ratio (S/N) the simple cells achieve the same performance as resulted from the psychophysical experiment. Type I complex cells extract moving deterministic signals (i.e. bars) from the stationary noise, whereas in the answers of Type II complex cells the statistical parts of the signals predominate. Considering the different cell types each as a series of a linear and a nonlinear system one obtains the cell specific space-time freq…

Early GABAergic circuitry in the cerebral cortex.

2013

In the cerebral cortex GABAergic signaling plays an important role in regulating early developmental processes, for example, neurogenesis, migration and differentiation. Transient cell populations, namely Cajal-Retzius in the marginal zone and thalamic input receiving subplate neurons, are integrated as active elements in transitory GABAergic circuits. Although immature pyramidal neurons receive GABAergic synaptic inputs already at fetal stages, they are integrated into functional GABAergic circuits only several days later. In consequence, GABAergic synaptic transmission has only a minor influence on spontaneous network activity during early corticogenesis. Concurrent with the gradual devel…

Activity-Dependent Regulation of Neuronal Apoptosis in Neonatal Mouse Cerebral Cortex

2007

A massive neuronal loss during early postnatal development has been well documented in the murine cerebral cortex, but the factors that drive cells into apoptosis are largely unknown. The role of neuronal activity in developmental apoptosis was studied in organotypic neocortical slice cultures of newborn mice. Multielectrode array and whole-cell patch-clamp recordings revealed spontaneous network activity characterized by synchronized burst discharges, which could be blocked by tetrodotoxin and ionotropic glutamate receptor antagonists. The identical neuropharmacological manipulations also caused a significant increase in the number of apoptotic neurons as early as 6 h after the start of dr…

Photoperiod-temperature and neuroblast proliferation-migration in the adult lizard cortex.

1997

The lizard medial cortex (a zone homologous to the mammalian fascia dentata) shows delayed postnatal neurogenesis throughout the lifetime of these animals. Experimental lesioning of this area is followed by neuronal regeneration, a unique phenomenon in the adult amniote telencephalon. The differential effects of temperature and photoperiod on postnatal neurogenetic activity were studied using tritiated thymidine pulses and posterior autoradiography as well as proliferating cell nuclear antigen (PCNA) immunostaining. Long (summer) photoperiods increased the number of proliferating neuroblasts in the ependymal neuroepithelium. Cold (winter) temperature prevented migration of the newly generat…