Search results for "Neural Inhibition"
showing 10 items of 76 documents
Increased cross-education of muscle strength and reduced corticospinal inhibition following eccentric strength training.
2015
Aim: Strength training of one limb results in a substantial increase in the strength of the untrained limb, however, it remains unknown what the corticospinal responses are following either eccentric or concentric strength training and how this relates to the cross-education of strength. The aim of this study was to determine if eccentric or concentric unilateral strength training differentially modulates corticospinal excitability, inhibition and the cross-transfer of strength. Methods: Changes in contralateral (left limb) concentric strength, eccentric strength, motor-evoked potentials, short-interval intracortical inhibition and silent period durations were analyzed in groups of young ad…
High-Frequency Transcranial Magnetic Stimulation on Motor Cortex of Patients Affected by Migraine With Aura: A Way to Restore Normal Cortical Excitab…
2009
We showed reduced motor intracortical inhibition (ICI) and paradoxical increase of intracortical facilitation (ICF) to 1 Hz repetitive transcranial magnetic stimulation (rTMS) in patients affected by migraine with aura (MA). In conditions of enhanced excitability due to a reduced inhibition, high-frequency rTMS was found to potentiate intracortical inhibition. Here we explored the conditioning effects of high-frequency priming stimulation of motor cortex with the aim of normalizing excitability reverting paradoxical facilitation by 1 Hz rTMS in MA. Nine patients with MA and nine healthy controls underwent a paired-pulse TMS paradigm to evaluate motor intracortical excitability (ICI and ICF…
Alterations in the expression of PSA-NCAM and synaptic proteins in the dorsolateral prefrontal cortex of psychiatric disorder patients.
2012
Alterations in the structure and physiology of the prefrontal cortex (PFC) have been found in different psychiatric disorders and some of them involve inhibitory networks, especially in schizophrenia and major depression. Changes in the structure of these networks may be mediated by the polysialylated neural cell adhesion molecule (PSA-NCAM), a molecule related to neuronal structural plasticity, expressed in the PFC exclusively by interneurons. Different studies have found that PSA-NCAM expression in the hippocampus and the amygdala is altered in schizophrenia, major depression and animal models of these disorders, in parallel to changes in the expression of molecules related to inhibitory …
Modulatory effects of the novel TrkB receptor agonist 7,8-dihydroxyflavone on synaptic transmission and intrinsic neuronal excitability in mouse visu…
2013
7,8-Dihydroxyflavone (7,8 DHF) is a new recently identified TrkB receptor agonist, which possesses a potent neurotrophic activity and shares many physiological properties with the neurotrophin "Brain Derived Neurotrophic Factor" (BDNF). However, its precise mechanism of action at the cellular level has not been clarified yet. In the present study we explored the effects of this agent on synaptic and intrinsic neuronal properties by performing whole-cell patch clamp recordings from layer 2/3 pyramidal neurons. Incubation of acute cortical slices with 7,8-DHF (20 µM) for 30 min caused a selective reduction in the strength of GABAergic inhibition. The amplitude of evoked inhibitory postsynapti…
GABA, receptor mediated fast synaptic inhibition in the rabbit brain-stem respiratory system
1991
The involvement of GABA mediated neurotransmission in the central control of respiration was investigated by administration of the specific GABAA receptor agonist muscimol and the specific GABAA receptor antagonist biculline into the fourth cerebral ventricle of the rabbit. Cycle-triggered averaging of the phrenic nerve activity (PNA) was used to quantify drug-induced changes of the central respiratory pattern. Muscimol reduced the peak amplitude of PNA and increased the duration of the respiratory phases. High amounts of muscimol led to a long-lasting but reversible central apnea. Bicuculline very effectively blocked the effects of externally applied muscimol. Blockade of intrinsically act…
Non-adrenergic non-cholinergic nerve-mediated inhibitory control of pigeon oesophageal muscle.
1996
Pigeon oesophageal smooth muscle in vitro has spontaneous electromechanical activity. In the presence of atropine and guanethidine, electrical field stimulation evokes a transient TTX-sensitive response comprising inhibition of electric bursting activity and muscular relaxation. This NANC inhibitory response was analysed using the K+ channel blockers TEA and apamin, TEA perfusion (0.1-5 mM) induced a concentration-dependent reduction in amplitude of EFS-evoked relaxation. Responses to higher stimulation frequencies were more sensitive to TEA than those to lower ones. The maximum reduction in amplitude (29% of control) was obtained on 30 Hz EFS evoked responses during 5 mM TEA perfusion. In …
Cooling of the cerebellar interpositus nucleus abolishes somatosensory cortical learning-related activity in eyeblink conditioned rabbits.
2005
Nictitating membrane movement and multiple-unit activity in the somatosensory cortex were recorded from rabbits during paired (N = 6) and unpaired (N = 5) presentations of a tone conditioned stimulus (CS) and an airpuff unconditioned stimulus (US). A behavioural conditioned response (CR) to the CS and an accompanying neural response in the somatosensory cortex developed only in the paired group. Inactivation of the cerebellar interpositus nucleus abolished both the acquired CR and the accompanying neural response. However, the CS facilitated both behavioural and neural responses to the US during the inactivation. Thus, the absence of the CR could not be accounted for by the general inabilit…
Modulation of excitatory and inhibitory circuits for visual awareness in the human right parietal cortex.
2005
The balance of specific patterns of excitation and inhibition in critical regions of both hemispheres could be relevant in orienting attention over the extrapersonal space. In the present study a group of normal subjects had to detect small rectangular stimuli presented briefly on a computer screen in three different conditions: unilateral presentation either to left or right visual periphery or bilateral simultaneous presentation. Paired transcranial magnetic stimulation (TMS), was applied over the right parietal cortex 150 ms after the presentation of the visual stimuli with different inter-stimulus intervals (ISIs: 1, 3,5 and 10 ms). When paired TMS was applied 150 ms, but not 100 ms, af…
Nrg1 haploinsufficiency alters inhibitory cortical circuits
2021
Neuregulin 1 (NRG1) and its receptor ERBB4 are schizophrenia (SZ) risk genes that control the development of both excitatory and inhibitory cortical circuits. Most studies focused on the characterization ErbB4 deficient mice. However, ErbB4 deletion concurrently perturbs the signaling of Nrg1 and Neuregulin 3 (Nrg3), another ligand expressed in the cortex. In addition, NRG1 polymorphisms linked to SZ locate mainly in non-coding regions and they may partially reduce Nrg1 expression. Here, to study the relevance of Nrg1 partial loss-of-function in cortical circuits we characterized a recently developed haploinsufficient mouse model of Nrg1 (Nrg1tm1Lex). These mice display SZ-like behavioral d…
Inhibition of adult hippocampal neurogenesis disrupts contextual learning but spares spatial working memory, long-term conditional rule retention and…
2009
Neurogenesis in the adult dentate gyrus (DG) of the hippocampus has been implicated in neural plasticity and cognition but the specific functions contributed by adult-born neurons remain controversial. Here, we have explored the relationship between adult hippocampal neurogenesis and memory function using tasks which specifically require the participation of the DG. In two separate experiments several groups of rats were exposed to fractionated ionizing radiation (two sessions of 7 Gy each on consecutive days) applied either to the whole brain or focally, aiming at a region overlying the hippocampus. The immunocytochemical assays showed that the radiation significantly reduced the expressio…