Search results for "Cortex"
showing 10 items of 1827 documents
Changes in intracortical circuits of the human motor cortex following theta burst stimulation of the lateral cerebellum
2008
Objective: The cerebellum takes part in several motor functions through its influence on the motor cortex (M1). Here, we applied the theta burst stimulation (TBS) protocol, a novel form of repetitive Transcranial Magnetic Stimulation (rTMS) over the lateral cerebellum. The aim of this study was to test whether TBS of the lateral cerebellum could be able to modulate the excitability of the contralateral M1 in healthy subjects. Methods: Motor-evoked potentials (MEPs) amplitude, short intracortical inhibition (SICI), long intracortical inhibition (LICI) and short intracortical facilitation (SICF) were tested in the M1 before and after cerebellar continuous TBS (cTBS) or intermittent TBS (iTBS)…
Local Cerebral Blood Flow in a Rat Cortical Vein Occlusion Model
1996
The symptoms following sinus and vein occlusion observed in patients and experimental animals display a considerable variability that so far remains largely unexplained. In a rat cortical vein occlusion model using a photochemical thrombotic technique, we examined changes in the cerebral venous flow pattern by fluorescence angiography and regional cerebral blood flow (rCBF) and cerebral blood volume fraction (CBVF) by a modern laser Doppler “scanning” technique. Brain damage was assessed histologically. Fluorescence angiographic findings fell into two groups: group A, rats with an altered venous flow pattern after occlusion (n = 12), and group B, rats with interruption of blood flow and/or…
Novel complement C1 inhibitor BSF468248 does not improve brain damage after cortical vein occlusion
2003
BSF468248 is a novel potent complement C1 inhibitor. To determine whether BSF468248 is effective against focal cerebral ischemia, we evaluated the change of cerebral blood flow (CBF) and infarction volume using a photochemically-induced cortical vein occlusion model in rats in blind studies. In 22 Wistar rats, two adjacent cortical veins were occluded by photochemical thrombosis and fiberoptic illumination under controlled anesthesia and ventilation. Just after the occlusion, BSF468248 or physiological saline was administrated. In the low-dose study, a treatment group (n = 7) was administered BSF468248 1 mg/kg bolus and 1 mg/kg continuously for 30 min. The same volume of saline was given to…
Cluster analysis of mrna expression levels identifies multiple sequential patterns following focal cerebral ischemia
2012
AIM The purpose of this study is to detect gene expression patterns following focal cerebral ischemia. MATERIAL AND METHODS 25 male Wistar rats were divided into control (n = 8) and ischemic (n = 17) groups. In the ischemic group, slowly progressing focal ischemia was simulated by two-vein occlusion with spreading depression (SD) a cortical microinjection of KCl induced. Ischemic tissue was removed at 2, 8, 24, or 72 h postischemia. Using semiquantitative reverse transcription polymerase chain reaction, we investigated mRNA expression levels of 13 representative genes related to cerebral ischemia. Cluster analysis of the gene expression levels was done. RESULTS In the ischemic group, the ex…
The default mode network and the working memory network are not anti-correlated during all phases of a working memory task
2015
INTRODUCTION:\ud \ud The default mode network and the working memory network are known to be anti-correlated during sustained cognitive processing, in a load-dependent manner. We hypothesized that functional connectivity among nodes of the two networks could be dynamically modulated by task phases across time.\ud METHODS:\ud \ud To address the dynamic links between default mode network and the working memory network, we used a delayed visuo-spatial working memory paradigm, which allowed us to separate three different phases of working memory (encoding, maintenance, and retrieval), and analyzed the functional connectivity during each phase within and between the default mode network and the …
Investigating individual stress reactivity: High hair cortisol predicts lower acute stress responses
2020
Identifying individual differences in stress reactivity is of particular interest in the context of stress-related disorders and resilience. Previous studies already identified several factors mediating the individual stress response of the hypothalamus-pituitary-adrenal axis (HPA). However, the impact of long-term HPA axis activity on acute stress reactivity remains inconclusive. To investigate associations between long-term HPA axis variation and individual acute stress reactivity, we tested 40 healthy volunteers for affective, endocrine, physiological, and neural reactions to a modified, compact version of the established in-MR stress paradigm ScanSTRESS (ScanSTRESS-C). Hair cortisol con…
Transient topographical amnesia and cingulate cortex damage: A case report
1996
Transient topographical amnesia (TTA) is the temporary inability to find one's way in familiar or unfamiliar surroundings due to the inability to use well known environmental landmarks for route finding. The syndrome has not been described as having any obvious aetiology and has been thought to be caused by a vascular deficit in right hemispheric structures which are crucial for topographic recognition, i.e. parietal association and parahippocampal cortex. The patient described in the present study complained of several critical episodes of TTA and tonic rigidity of the left limbs. Neuropsychological assessment was normal except for a deficit in spatial memory tasks. Magnetic resonance (MR)…
Inhibition processes are dissociable and lateralized in human prefrontal cortex
2016
The prefrontal cortex (PFC) is known to make fundamental contributions to executive functions. However, the precise nature of these contributions is incompletely understood. We focused on a specific executive function, inhibition, the ability to suppress a pre-potent response. Functional imaging and animal studies have studied inhibition. However, there are only few lesion studies, typically reporting discrepant findings. For the first time, we conducted cognitive and neuroimaging investigations on patients with focal unilateral PFC lesions across two widely used inhibitory tasks requiring a verbal response: The Hayling Part 2 and Stroop Colour-Word Tests. We systematically explored the rel…
A fronto-parietal network is mediating improvement of motor function related to repetitive peripheral magnetic stimulation: A PET-H2O15 study.
2006
Repetitive peripheral magnetic stimulation (RPMS) is a focused and painless stimulation method, in which muscle contractions are elicited by depolarization of the terminal motor branches. Clinical-experimental investigations on different disorders of sensorimotor integration in the last decade have shown that RPMS can be used for the rehabilitation of motor functions after stroke. It is supposed that this therapeutic effect is based on the RPMS-induced proprioceptive inflow to the CNS. To analyze the conditioning effects of RPMS on reorganization of the motor system on cortical level positron emission tomography (PET) is used. Regional cerebral blood flow (rCBF) has been measured using H(2)…
Distinct patterns of Fos immunoreactivity in striatum and hippocampus induced by different kinds of novelty in mice.
2010
In this study the immediate-early gene Fos was used to investigate the response to different novel stimuli in a wide array of brain regions including the hippocampus, the rhinal cortex, the frontal cortex and different components of the striatal complex. Independent groups of CD-1 mice were exposed to three different novelty conditions: (1) novel environment (empty open field); (2) complex novel environment (i.e. open field containing objects); and (3) identity-based detection of novel objects. We observed that a complex novel environment and a knowledge-based novelty modulated Fos levels in both the dorsal and the ventral components of the striatum, while Fos immunoreactivity in the medial…