Search results for "cortex"
showing 10 items of 1827 documents
Effects of low-gamma tACS on primary motor cortex in implicit motor learning
2019
Abstract In the primary motor cortex (M1), rhythmic activity in the gamma frequency band has been found during movement planning, onset and execution. Although the role of high-gamma oscillatory activity in M1 is well established, the contribution of low-gamma activity is still unexplored. In this study, transcranial alternating current stimulation (tACS) was used with the aim to specifically modulate low-gamma frequency band in M1, during an implicit motor learning task. A 40 Hz-tACS was applied over the left M1 while participants performed a serial reaction time task (SRTT) using their right hand. The task required the repetitive execution of sequential movements in response to sequences …
Interference of left and right cerebellar rTMS with procedural learning.
2004
Abstract Increasing evidence suggests cerebellar involvement in procedural learning. To further analyze its role and to assess whether it has a lateralized influence, in the present study we used a repetitive transcranial magnetic stimulation interference approach in a group of normal subjects performing a serial reaction time task. We studied 36 normal volunteers: 13 subjects underwent repetitive transcranial magnetic stimulation on the left cerebellum and performed the task with the right (6 subjects) or left (7 subjects) hand; 10 subjects underwent repetitive transcranial magnetic stimulation on the right cerebellum and performed the task with the hand ipsilateral (5 subjects) or contral…
The role of the dorsolateral prefrontal cortex in implicit procedural learning.
1996
We studied the role of the dorsolateral prefrontal cortex in procedural learning. Normal subjects completed several blocks of a serial reaction time task using only one hand without or with concurrent non-invasive repetitive transcranial magnetic stimulation. To disrupt their function transiently, stimulation was applied at low intensity over the supplementary motor area or over the dorsolateral prefrontal cortex contralateral or ipsilateral to the hand used for the test. Stimulation to the contralateral dorsolateral prefrontal cortex markedly impaired procedural implicit learning, as documented by the lack of significant change in response times during the task. Stimulation over the other …
Functional Role of Cerebellar Gamma Frequency in Motor Sequences Learning: a tACS Study
2021
Although the role of the cerebellum in motor sequences learning is widely established, the specific function of its gamma oscillatory activity still remains unclear. In the present study, gamma (50 Hz)—or delta (1 Hz)—transcranial alternating current stimulation (tACS) was applied to the right cerebellar cortex while participants performed an implicit serial reaction time task (SRTT) with their right hand. The task required the execution of motor sequences simultaneously with the presentation of a series of visual stimuli. The same sequence was repeated across multiple task blocks (from blocks 2 to 5 and from blocks 7 to 8), whereas in other blocks, new/pseudorandom sequences were reproduce…
Chemogenetic Suppression of the Subthalamic Nucleus Induces Attentional Deficits and Impulsive Action in a Five-Choice Serial Reaction Time Task in M…
2020
The subthalamic nucleus (STN), a key component of the basal ganglia circuitry, receives inputs from broad cerebral cortical areas and relays cortical activity to subcortical structures. Recent human and animal studies have suggested that executive function, which is assumed to consist of a set of different cognitive processes for controlling behavior, depends on precise information processing between the cerebral cortex and subcortical structures, leading to the idea that the STN contains neurons that transmit the information required for cognitive processing through their activity, and is involved in such cognitive control directly and dynamically. On the other hand, the STN activity also …
Transcranial magnetic stimulation and neuroplasticity
1998
We review past results and present novel data to illustrate different ways in which TMS can be used to study neural plasticity. Procedural learning during the serial reaction time task (SRTT) is used as a model of neural plasticity to illustrate the applications of TMS. These different applications of TMS represent principles of use that we believe are applicable to studies of cognitive neuroscience in general and exemplify the great potential of TMS in the study of brain and behavior. We review the use of TMS for (1) cortical output mapping using focal, single-pulse TMS; (2) identification of the mechanisms underlying neuroplasticity using paired-pulse TMS techniques; (3) enhancement of th…
Central Serotonin2C Receptor: From Physiology to Pathology
2006
Since the 1950s, when serotonin (5-HT) was discovered in the mammalian central nervous system (CNS), an enormous amount of experimental evidence has revealed the pivotal role of this biogenic amine in a number of cognitive and behavioural functions. Although 5-HT is synthesized by a small group of neurons within the raphe nuclei of the brain stem, almost all parts of the CNS receive serotonergic projections. Furthermore, the importance of 5-HT modulation and the fine-tuning of its action is underlined by the large number of 5-HT binding sites found in the CNS. Hitherto, up to 15 different 5-HT receptors subtypes have been identified. This review was undertaken to summarize the work that has…
Serotoninergic innervation of nonprincipal cells in the cerebral cortex of the lizard Podarcis hispanica.
2004
The mechanism of serotoninergic transmission in the neo- and archicortex of mammals kis complex, including both synaptic and nonsynaptic components, direct actions on principal cells, and indirect effects mediated by GABAergic interneurons. Here we studied the termination pattern and synaptic organization of the serotoninergic afferents in the cerebral cortex of the lizard, Podarcis hispanica, which is considered to correspond in part to the mammalian hippocampal formation, with the aim of unraveling basic, phylogenetically preserved rules in the connectivity of this pathway. We demonstrate that serotoninergic afferents, visualized by immunostaining for serotonin itself, establish multiple …
The role of neurosteoids sulphate in a spatial and object recognition learning task
2012
The term “neuroactive steroid” refers to steroids that have rapid modulatory effects on ligand-gated ion channels via non-genomic mechanism. Specifically, neurosteroids can alter neuronal excitability via the cell surface interacting with specific neurotransmitter receptors. The neurosteroid pregnenolone sulphate (PREGS) has been described as negative modulator of GABAA receptor and positive modulator of NMDA receptor, affecting cognition as well as emotionality. The present study was aimed to assess the effects of the acute administration of PREGS (10 mg/Kg, s. c.) on rats cognitive functions using a novel task, the Can test. This task explores, under reinforcement, the spatial/visual cues…
Atrial natriuretic peptide (ANP) and oxytocin-expression in the adult rat and mouse cerebellum.
2015
Abstract Background: Many studies are in the literature on the ANP and oxytocin-presence in the brain, but very few studies with controversial results are reported on the presence of these peptides in the cerebellum. This immunohistochemical study investigates on the ANP and oxytocin-presence in the cerebellum of the adult rat and mouse rodents. Results: This study, firstly, evidences the ANP- immunopositivity in cerebellar cortex of both rat and mouse rodents. In rat the molecular layer presents some few immunopositive fibers, but no neuron resulted immunopositive; the granular and Purkinje cells are immunopositive. In mouse the cerebellar cortex ANP-immunopositivity is present in all laye…