Search results for "Cortex"
showing 10 items of 1827 documents
Cognitive estimation: Performance of patients with focal frontal and posterior lesions
2018
The Cognitive Estimation Test (CET) is a widely used test to investigate estimation abilities requiring complex processes such as reasoning, the development and application of appropriate strategies, response plausibility checking as well as general knowledge and numeracy (e.g., Shallice and Evans, 1978; MacPherson et al., 2014). Thus far, it remains unknown whether the CET is both sensitive and specific to frontal lobe dysfunction. Neuroimaging techniques may not represent a useful methodology for answering this question since the complex processes involved are likely to be associated with a large network of brain regions, some of which are not functionally necessary to successfully carry …
Tissue oxygenation in brain, muscle and fat in a rat model of sleep apnea: differential effect of obstructive apneas and intermittent hypoxia.
2011
Study Objectives: To test the hypotheses that the dynamic changes in brain oxygen partial pressure (PtO 2) in response to obstructive apneas or to intermittent hypoxia differ from those in other organs and that the changes in brain PtO 2 in response to obstructive apneas is a source of oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: 98 Sprague-Dawley rats. Interventions: Cerebral cortex, skeletal muscle, or visceral fat tissues were exposed in anesthetized animals subjected to either obstructive apneas or intermittent hypoxia (apneic and hypoxic events of 15 s each and 60 events/h) for 1 h. Measurements and Results: Arterial oxyge…
Enhancement of brain event-related potentials to speech sounds is associated with compensated reading skills in dyslexic children with familial risk …
2014
Specific reading disability, dyslexia, is a prevalent and heritable disorder impairing reading acquisition characterized by a phonological deficit. However, the underlying mechanism of how the impaired phonological processing mediates resulting dyslexia or reading disabilities remains still unclear. Using ERPs we studied speech sound processing of 30 dyslexic children with familial risk for dyslexia, 51 typically reading children with familial risk for dyslexia, and 58 typically reading control children. We found enhanced brain responses to shortening of a phonemic length in pseudo-words (/at:a/ vs. /ata/) in dyslexic children with familial risk as compared to other groups. The enhanced bra…
Auditory event-related potentials show altered hemispheric responses in dyslexia
2011
Dyslexia is characterized by deficits in phonological processing abilities. However, it is unclear what the underlying factors for poor phonological abilities or speech sound representations are. One hypothesis suggests that individuals with dyslexia have problems in basic acoustic perception which in turn can also cause problems in speech perception. Here basic auditory processing was assessed by auditory event-related potentials recorded for paired tones presented in an oddball paradigm in 9-year-old children with dyslexia and a familial background of dyslexia, typically reading children at familial risk for dyslexia and control children without risk for dyslexia. The tone pairs elicited …
Disruption of the ASTN2 / TRIM32 locus at 9q33.1 is a risk factor in males for Autism Spectrum Disorders, ADHD and other neurodevelopmental phenotypes
2014
Rare copy number variants (CNVs) disrupting ASTN2 or both ASTN2 and TRIM32 have been reported at 9q33.1 by genome-wide studies in a few individuals with neurodevelopmental disorders (NDDs). The vertebrate-specific astrotactins, ASTN2 and its paralog ASTN1, have key roles in glial-guided neuronal migration during brain development. To determine the prevalence of astrotactin mutations and delineate their associated phenotypic spectrum, we screened ASTN2/TRIM32 and ASTN1 (1q25.2) for exonic CNVs in clinical microarray data from 89 985 individuals across 10 sites, including 64 114 NDD subjects. In this clinical dataset, we identified 46 deletions and 12 duplications affecting ASTN2. Deletions o…
Chronic restraint stress and chronic corticosterone treatment modulate differentially the expression of molecules related to structural plasticity in…
2004
Stress and stress-related hormones induce structural changes in neurons of the adult CNS. Neurons in the hippocampus, the amygdala and the prefrontal cortex undergo neurite remodeling after chronic stress. In the hippocampus some of these effects can be mimicked with chronic administration of adrenal steroids. These changes in neuronal structure may be mediated by certain molecules related to plastic events such as the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). The expression of PSA-NCAM persists in the adult hippocampus and it is up-regulated after chronic stress. The piriform cortex also displays considerable levels of PSA-NCAM during adulthood and indirect evide…
Expression of α4-1 and α5 Nicotinic Cholinoceptor mRNA in the Aging Rat Cerebral Cortex
1997
Although important in neurodegeneration, systematic studies of nicotinic acetylcholine receptor expression in normal aging human brains are difficult to perform. We have studied the expression of nicotinic receptor alpha 4-1 and alpha 5 mRNA in the frontal and parietal isocortex of 3- (young adult), 24- (late middle aged), and 33-month-old (old) rats by nonisotopic in situ hybridization. In all groups transcripts were mainly present in layer II/III and V pyramidal neurons. The numerical densities of alpha 4-1 mRNA-containing neurons with respect to those of cresyl violet-stained neurons decreased with aging in the rat frontal and parietal cortex, while those of alpha 5 mRNA-containing neuro…
Cortical networks of procedural learning: Evidence from cerebellar damage
2007
The lateral cerebellum plays a critical role in procedural learning that goes beyond the strict motor control functions attributed to it. Patients with cerebellar damage show marked impairment in the acquisition of procedures, as revealed by their performance on the serial reaction time task (SRTT). Here we present the case of a patient affected by ischemic damage involving the left cerebellum who showed a selective deficit in procedural learning while performing the SRTT with the left hand. The deficit recovered when the cortical excitability of an extensive network involving both cerebellar hemispheres and the dorsolateral prefrontal cortex (DLPFC) was decreased by low-frequency repetitiv…
Acute behavioural and neurotoxic effects of MDMA plus cocaine in adolescent mice.
2008
The poly-drug pattern is the most common among those observed in MDMA users, with cocaine being a frequently associated drug. This study evaluates the acute effects of MDMA (5, 10 and 20 mg/kg), alone or in combination with cocaine (25 mg/kg), on motor activity, anxiety (elevated plus maze and social interaction test), memory and brain monoamines in adolescent mice, Both drugs, administered alone or concurrently, produced hyperactivity and a decrease in social contacts. However, an anxiolytic effect, studied by means of the elevated plus maze and expressed as an increase in the time spent on the open arms, was observed only in those animals treated with cocaine and MDMA. The passive avoidan…
Serotonin, the Prefrontal Cortex, and the Antidepressant-Like Effect of Cannabinoids
2007
Preclinical and clinical studies show that cannabis modulates mood and possesses antidepressant-like properties, mediated by the agonistic activity of cannabinoids on central CB1 receptors (CB1Rs). The action of CB1R agonists on the serotonin (5-HT) system, the major transmitter system involved in mood control and implicated in the mechanism of action of antidepressants, remains however poorly understood. In this study, we demonstrated that, at low doses, the CB1R agonist WIN55,212-2 [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate] exerts potent antidepressant-like properties in the rat forced-swim test (FST). This effect …