Search results for "pathways"
showing 10 items of 644 documents
Chemoarchitecture and afferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes.
2004
The olfactostriatum, a portion of the striatal complex of snakes, is the major tertiary vomeronasal structure in the ophidian brain, receiving substantial afferents from the nucleus sphericus, the primary target of accessory olfactory bulb efferents. In the present study, we have characterized the olfactostriatum of garter snakes (Thamnophis sirtalis) on the basis of chemoarchitecture (distribution of serotonin, neuropeptide Y and tyrosine hydroxylase) and hodology (afferent connections). The olfactostriatum is densely immunoreactive for serotonin and neuropeptide Y and shows moderate-to-weak immunoreactivity for tyrosine hydroxylase. In addition to afferents from the nucleus sphericus, the…
Alteration of inhibitory circuits in the somatosensory cortex of Ts65Dn mice, a model for Down's syndrome.
2010
Down’s syndrome (DS), with an incidence of one in 800 live births, is the most common genetic disorder associated with mental retardation. This trisomy on chromosome 21 induces a variable phenotype in which the only common feature is the presence of mental retardation. The neural mechanisms underlying mental retardation might include defects in the formation of neuronal networks and neural plasticity. DS patients have alterations in the morphology, the density and the distribution of dendritic spines in the pyramidal neurons of the cortex. Our hypothesis is that the deficits in dendritic arborization observed in the principal neurons of DS patients and Ts65Dn mice (a model for DS that mimic…
Age-related differences in a delayed pointing of a M�ller-Lyer illusion
2003
It has been suggested that movements to visible or remembered targets are differently sensitive to the Müller-Lyer (ML) illusion. Indeed, when the target is continuously visible, movements rely on the veridical object characteristics, whereas remembered movements are thought to reflect the perceived characteristics of the object. The aim of the present study was to determine how movements to visible or remembered targets are influenced by the ML illusion in children aged 7 to 11 years old. Participants were asked to make a perceptual judgment or to point a shaft extremity of the ML configurations (Closed, Control, and Open) in three visual conditions (Closed Loop, Open Loop-0-s delay, and 5…
Cognitive reserve impacts on inter-individual variability in resting-state cerebral metabolism in normal aging
2012
There is a great deal of heterogeneity in the impact of aging on cognition and cerebral functioning. One potential factor contributing to individual differences among the elderly is the cognitive reserve, which designates the partial protection from the deleterious effects of aging that lifetime experience provides. Neuroimaging studies examining task-related activation in elderly people suggested that cognitive reserve takes the form of more efficient use of brain networks and/or greater ability to recruit alternative networks to compensate for age-related cerebral changes. In this exploratory multi-center study, we examined the relationships between cognitive reserve, as measured by educa…
Color-coded diffusion-tensor-imaging of posterior cingulate fiber tracts in mild cognitive impairment.
2005
Abstract Different processes like microvascular dysfunction, free radical toxicity, β-amyloid deposits, and Wallerian degeneration can cause functionally relevant disturbances of cerebral neuronal networks by myelin degeneration. Color-coded diffusion-tensor-imaging (ccDTI) allows the structural identification and quantification of myelinated fiber tracts. Particularly, posterior cingulate fiber tracts, which are regarded as important neuronal substrates of the network representing memory processing can be localized only imprecisely by conventional magnetic resonance imaging techniques. The posterior cingulate bundles were assessed by ccDTI in 17 patients with amnestic mild cognitive impair…
Comparison of motor strategies in sit-to-stand and back-to-sit motions between healthy and Alzheimer’s disease elderly subjects
2005
We studied the kinematics of shoulder displacement during sit-to-stand and back-to-sit in 6 healthy elderly subjects and six elderly subjects with mild to moderate Alzheimer's disease in order to elucidate the impact of Alzheimer's disease on motor planning and control processes. During sit-to-stand, Alzheimer's disease subjects reduced their forward displacement and started their upward displacement earlier than healthy elderly subjects. Furthermore, shoulder path curvatures were more pronounced for upward compared with downward displacement in healthy elderly group, in contrast with Alzheimer's disease group. Temporal analysis found that: 1) for both groups, profiles of velocity of sit-to…
Odorant metabolism catalyzed by olfactory mucosal enzymes influences peripheral olfactory responses in rats.
2013
International audience; A large set of xenobiotic-metabolizing enzymes (XMEs), such as the cytochrome P450 monooxygenases (CYPs), esterases and transferases, are highly expressed in mammalian olfactory mucosa (OM). These enzymes are known to catalyze the biotransformation of exogenous compounds to facilitate elimination. However, the functions of these enzymes in the olfactory epithelium are not clearly understood. In addition to protecting against inhaled toxic compounds, these enzymes could also metabolize odorant molecules, and thus modify their stimulating properties or inactivate them. In the present study, we investigated the in vitro biotransformation of odorant molecules in the rat …
Change detection to tone pairs during the first year of life – Predictive longitudinal relationships for EEG-based source and time-frequency measures
2019
Abstract Brain responses related to auditory processing show large changes throughout infancy and childhood with some evidence that the two hemispheres might mature at different rates. Differing rates of hemispheric maturation could be linked to the proposed functional specialization of the hemispheres in which the left auditory cortex engages in analysis of precise timing information whereas the right auditory cortex focuses on analysis of sound frequency. Here the auditory change detection process for rapidly presented tone-pairs was examined in a longitudinal sample of infants at the age of 6 and 12 months using EEG. The ERP response related to change detection of a frequency contrast, i…
Nitric oxide synthase in identified olivocochlear projection neurons in rat and guinea pig.
1999
Nitric oxide (NO) is thought to be involved in the effects of amino acids at the level of cochlear hair cell afferents. Recently, the isoform of the NO-producing enzyme, neuronal NO synthase (nNOS), has been demonstrated in neuronal structures of the cochlea in rats and guinea pigs histochemically and immunohistochemically. To investigate the sources of cochlear NO, we injected Fluoro-Gold (FG) into the cochlea of rats and guinea pigs. Upon terminal uptake of the tracer and neuronal transport we observed FG in terminals at the base of inner (IHC) and outer hair cells (OHC) and in neurons of the spiral ganglion. Ganglion cells and terminals at the IHC were clearly nNOS-positive, while termin…
Olfacto-retinalis pathway in Austrolebias charrua fishes: A neuronal tracer study
2013
Abstract The olfacto-retinal centrifugal system, a constant component of the central nervous system that appears to exist in all vertebrate groups, is part of the terminal nerve (TN) complex. TN allows the integration of different sensory modalities, and its anatomic variability may have functional and evolutionary significance. We propose that the olfacto-retinal branch of TN is an important anatomical link that allows the functional interaction between olfactory and visual systems in Austrolebias . By injecting three different neuronal tracers (biocytin, horseradish peroxidase, and 1,1′-dioctadecyl-3,3,3′,3′tetramethyl-indocarbocyanine perchlorate (DiI)) in the left eye of Austrolebias ch…