Oscillatory Activity (oscillatory + activity)

Distribution by Scientific Domains


Selected Abstracts


Behavioral relevance of gamma-band activity for short-term memory-based auditory decision-making

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2008
Jochen Kaiser
Abstract Oscillatory activity in the gamma-band range has been established as a correlate of cognitive processes, including perception, attention and memory. Only a few studies, however, have provided evidence for an association between gamma-band activity (GBA) and measures of behavioral performance. Here we focused on the comparison between sample and test stimuli S1 and S2 during an auditory spatial short-term memory task. Applying statistical probability mapping to magnetoencephalographic recordings from 28 human subjects, we identified GBA components distinguishing nonidentical from identical S1,S2 pairs. This activity was found at frequencies between 65 and 90 Hz and was localized over posterior cortical regions contralateral to the hemifield in which the stimuli were presented. The 10 best task performers showed higher amplitudes of this GBA component than the 10 worst performers. This group difference was most pronounced between about 150 and 300 ms after stimulus onset. Apparently the decision about whether test stimuli matched the stored representation of previously presented sample sounds relied partly on the oscillatory activation of networks representing differences between both stimuli. This result could be replicated by reanalyzing the combined data from two previous studies assessing short-term memory for sound duration and sound lateralization, respectively. Similarly to our main study, GBA amplitudes to nonmatching vs. matching S1,S2 pairs were higher in good performers than poor performers. The present findings demonstrate the behavioral relevance of GBA. [source]


Oscillatory activity in parietal and dorsolateral prefrontal cortex during retention in visual short-term memory: Additive effects of spatial attention and memory load

HUMAN BRAIN MAPPING, Issue 10 2009
Stéphan Grimault
Abstract We used whole-head magnetoencephalography to study the representation of objects in visual short-term memory (VSTM) in the human brain. Subjects remembered the location and color of either two or four colored disks that were encoded from the left or right visual field (equal number of distractors in the other visual hemifield). The data were analyzed using time-frequency methods, which enabled us to discover a strong oscillatory activity in the 8,15 Hz band during the retention interval. The study of the alpha power variation revealed two types of responses, in different brain regions. The first was a decrease in alpha power in parietal cortex, contralateral to the stimuli, with no load effect. The second was an increase of alpha power in parietal and lateral prefrontal cortex, as memory load increased, but without interaction with the hemifield of the encoded stimuli. The absence of interaction between side of encoded stimuli and memory load suggests that these effects reflect distinct underlying mechanisms. A novel method to localize the neural generators of load-related oscillatory activity was devised, using cortically-constrained distributed source-localization methods. Some activations were found in the inferior intraparietal sulcus (IPS) and intraoccipital sulcus (IOS). Importantly, strong oscillatory activity was also found in dorsolateral prefrontal cortex (DLPFC). Alpha oscillatory activity in DLPFC was synchronized with the activity in parietal regions, suggesting that VSTM functions in the human brain may be implemented via a network that includes bilateral DLPFC and bilateral IOS/IPS as key nodes. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]


Area-Specific Resonance of Excitatory Networks in Neocortex: Control by Outward Currents

EPILEPSIA, Issue 8 2007
Manuel A. Castro-Alamancos
Summary:, During disinhibition or low [Mg++]o buffer, 7,14 Hz (,10 Hz) oscillations are generated by excitatory networks of interconnected pyramidal cells in motor (agranular) cortex but are absent in barrel (granular) cortex. Here we studied if the inability of barrel cortex to produce ,10 Hz oscillations during these conditions is because barrel cortex networks lack the necessary cellular mechanisms or, alternatively, because those mechanisms are inhibited by outward currents. The results show that blockers of slowly inactivating voltage-dependent K+ currents unmask ,10 Hz oscillations in barrel cortex, and this occurs in unison with the unmasking of intrinsic inward Ca++ currents that are kept suppressed by the outward currents. Moreover, the ,10 Hz oscillations unmasked in barrel cortex occur independently in upper and lower layers indicating that the ,10 Hz oscillation mechanisms are kept suppressed in multiple networks. The results reveal that the propensity of distinct excitatory networks of neocortex to generate epileptiform oscillatory activities is controlled by outward currents. [source]


Oscillations in the basal ganglia under normal conditions and in movement disorders

MOVEMENT DISORDERS, Issue 10 2006
Plamen Gatev MD
Abstract A substantial body of work within the last decade has demonstrated that there is a variety of oscillatory phenomena that occur in the basal ganglia and in associated regions of the thalamus and cortex. Most of the earlier studies focused on recordings in rodents and primates. More recently, significant advances have been made in this field of research through the analysis of basal ganglia field potentials recorded from implanted deep brain stimulation electrodes in the basal ganglia of human patients with Parkinson's disease and other disorders. It now appears that oscillatory activity may play a significant role in the pathogenesis of these diseases. The most significant finding is that in Parkinson's disease synchronized oscillatory activity in the 10- to 35-Hz band (often termed ",-band") is prevalent in the basal ganglia,thalamocortical circuits, and that such activity can be reduced by dopaminergic treatments. The entrainment of large portions of these circuits may disrupt information processing in them and may lead to parkinsonian akinesia (and perhaps tremor). Although less firmly established than the role of oscillations in movement disorders, oscillatory activities at higher frequencies may also be a component of normal basal ganglia physiology. © 2006 Movement Disorder Society [source]


Sing the mind electric , principles of deep brain stimulation

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2010
Morten L. Kringelbach
Abstract The remarkable efficacy of deep brain stimulation (DBS) for a range of treatment-resistant disorders is still not matched by a comparable understanding of the underlying neural mechanisms. Some progress has been made using translational research with a range of neuroscientific techniques, and here we review the most promising emerging principles. On balance, DBS appears to work by restoring normal oscillatory activity between a network of key brain regions. Further research using this causal neuromodulatory tool may provide vital insights into fundamental brain function, as well as guide targets for future treatments. In particular, DBS could have an important role in restoring the balance of the brain's default network and thus repairing the malignant brain states associated with affective disorders, which give rise to serious disabling problems such as anhedonia, the lack of pleasure. At the same time, it is important to proceed with caution and not repeat the errors from the era of psychosurgery. [source]


Gamma activity and reactivity in human thalamic local field potentials

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2009
Florian Kempf
Abstract Depth recordings in patients with Parkinson's disease on dopaminergic therapy have revealed a tendency for oscillatory activity in the basal ganglia that is sharply tuned to frequencies of ,70 Hz and increases with voluntary movement. It is unclear whether this activity is essentially physiological and whether it might be involved in arousal processes. Here we demonstrate an oscillatory activity with similar spectral characteristics and motor reactivity in the human thalamus. Depth signals were recorded in 29 patients in whom the ventral intermediate or centromedian nucleus were surgically targeted for deep brain stimulation. Thirteen patients with four different pathologies showed sharply tuned activity centred at ,70 Hz in spectra of thalamic local field potential (LFP) recordings. This activity was modulated by movement and, critically, varied over the sleep,wake cycle, being suppressed during slow wave sleep and re-emergent during rapid eye movement sleep, which physiologically bears strong similarities with the waking state. It was enhanced by startle-eliciting stimuli, also consistent with modulation by arousal state. The link between this pattern of thalamic activity and that of similar frequency in the basal ganglia was strengthened by the finding that fast thalamic oscillations were lost in untreated parkinsonian patients, paralleling the behaviour of this activity in the basal ganglia. Furthermore, there was sharply tuned coherence between thalamic and pallidal LFP activity at ,70 Hz in eight out of the 11 patients in whom globus pallidus and thalamus were simultaneously implanted. Subcortical oscillatory activity at ,70 Hz may be involved in movement and arousal. [source]


Odor vapor pressure and quality modulate local field potential oscillatory patterns in the olfactory bulb of the anesthetized rat

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2008
Tristan Cenier
Abstract A central question in chemical senses is the way that odorant molecules are represented in the brain. To date, many studies, when taken together, suggest that structural features of the molecules are represented through a spatio-temporal pattern of activation in the olfactory bulb (OB), in both glomerular and mitral cell layers. Mitral/tufted cells interact with a large population of inhibitory interneurons resulting in a temporal patterning of bulbar local field potential (LFP) activity. We investigated the possibility that molecular features could determine the temporal pattern of LFP oscillatory activity in the OB. For this purpose, we recorded the LFPs in the OB of urethane-anesthetized, freely breathing rats in response to series of aliphatic odorants varying subtly in carbon-chain length or functional group. In concordance with our previous reports, we found that odors evoked oscillatory activity in the LFP signal in both the beta and gamma frequency bands. Analysis of LFP oscillations revealed that, although molecular features have almost no influence on the intrinsic characteristics of LFP oscillations, they influence the temporal patterning of bulbar oscillations. Alcohol family odors rarely evoke gamma oscillations, whereas ester family odors rather induce oscillatory patterns showing beta/gamma alternation. Moreover, for molecules with the same functional group, the probability of gamma occurrence is correlated to the vapor pressure of the odor. The significance of the relation between odorant features and oscillatory regimes along with their functional relevance are discussed. [source]


Prior pallidotomy reduces and modifies neuronal activity in the subthalamic nucleus of Parkinson's disease patients

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008
A. Zaidel
Abstract Parkinson's disease (PD) patients with prior radio-frequency lesions in the internal segment of the globus pallidus (GPi, pallidotomy), whose symptoms have deteriorated, may be candidates for further invasive treatment such as subthalamic deep brain stimulation (STN DBS). Six patients with prior pallidotomy (five unilaterally; one bilaterally) underwent bilateral STN DBS. The microelectrode recordings (MERs, used intraoperatively for STN verification), ipsilateral and contralateral to pallidotomy, and MERs from 11 matched PD patients who underwent bilateral STN DBS without prior pallidotomy were compared. For each trajectory, average, variance and mean successive difference (MSD, a measure of irregularity) of the root mean square (RMS) of the STN MER were calculated. The RMS in trajectories ipsilateral to pallidotomy showed significant reduction of the mean average and MSD of STN activity when compared with trajectories from patients without prior pallidotomy. The RMS parameters contralateral to pallidotomy tend to lie between those ipsilateral to pallidotomy and those without prior pallidotomy. The average STN power spectral density of oscillatory activity was notably lower ipsilateral to pallidotomy than contralateral, or without prior pallidotomy. The finding that pallidotomy reduces STN activity and changes firing characteristics, in conjunction with the effectiveness of STN DBS despite prior pallidotomy, calls for reappraisal and modification of the current model of the basal ganglia (BG) cortical network. It highlights the critical role of direct projections from the BG to brain-stem structures and suggests a possible GPi,STN reciprocal positive-feedback mechanism. [source]


GABAergic projections from the hippocampus to the retrosplenial cortex in the rat

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007
Toshio Miyashita
Abstract The retrosplenial cortex (RS) in rats has been implicated in a wide range of behaviors, including spatial navigation and memory. Relevant to this, the RS is closely interconnected with the hippocampus by multiple direct and indirect routes. Here, by injecting the retrograde tracer cholera toxin subunit B conjugated with Alexa488 (CTB-Alexa488) in the granular retrosplenial cortex (GRS), we demonstrate a moderately dense non-pyramidal projection from CA1. Neurons are in several layers, but mainly (about 65%) at the border of the stratum radiatum (SR) and stratum lacunosum moleculare (SLM). In particular, by double-labeling with GAD67 or ,-aminobutyric acid (GABA), we establish that these neurons are GABAergic. Further immunocytochemical screening for calcium-binding proteins, somatostatin (SS) or cholecystokinin (CCK) failed to identify additional neurochemical subgroups; but a small subset (about 14%) is positive for the m2 muscarinic acetylcholine receptor (M2R). Terminations target layer 1 of the GRS, as shown by biotinylated dextran amine (BDA) injections into CA1 and confirmed by a very superficial injection of CTB-Alexa488 in GRS. The superficial injection shows that there is a sparse GABAergic projection from the subiculum to layer 1 of the GRS, in addition to the dense excitatory connections to layer 3. The role of these dual inhibitory,excitatory pathways , within the subiculum, and in parallel from CA1 and the subiculum , remains to be determined, but may be related to synchronized oscillatory activity in the hippocampal complex and GRS, or to the generation of rhythmic activity within the GRS. [source]


A population-based model of the nonlinear dynamics of the thalamocortical feedback network displays intrinsic oscillations in the spindling (7,14 Hz) range

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2005
Nada A. B. Yousif
Abstract The thalamocortical network is modelled using the Wilson,Cowan equations for neuronal population activity. We show that this population model with biologically derived parameters possesses intrinsic nonlinear oscillatory dynamics, and that the frequency of oscillation lies within the spindle range. Spindle oscillations are an early sleep oscillation characterized by high-frequency bursts of action potentials followed by a period of quiescence, at a frequency of 7,14 Hz. Spindles are generally regarded as being generated by intrathalamic circuitry, as decorticated thalamic slices and the isolated thalamic reticular nucleus exhibit spindles. However, the role of cortical feedback has been shown to regulate and synchronize the oscillation. Previous modelling studies have mainly used conductance-based models and hence the mechanism relied upon the inclusion of ionic currents, particularly the T-type calcium current. Here we demonstrate that spindle-frequency oscillatory activity can also arise from the nonlinear dynamics of the thalamocortical circuit, and we use bifurcation analysis to examine the robustness of this oscillation in terms of the functional range of the parameters used in the model. The results suggest that the thalamocortical circuit has intrinsic nonlinear population dynamics which are capable of providing robust support for oscillatory activity within the frequency range of spindle oscillations. [source]


Enhancement of temporal and spatial synchronization of entorhinal gamma activity by phase reset

HIPPOCAMPUS, Issue 4 2002
Clayton T. Dickson
Abstract The synchronization of cortical gamma oscillatory activity (25,80 Hz) is thought to coordinate neuronal assemblies in the processing and storage of information. The mechanism by which independently oscillating and distantly located cortical zones become synchronized is presumed to involve activity in corticocortical connections, although evidence supporting this conjecture has only been indirect. In the present study, we show that activation of synaptic inputs within and to the medial entorhinal cortex (mEC) of the in vitro isolated guinea pig brain preparation resets the phase of ongoing gamma activity induced by muscarinic receptor agonism with carbachol (frequency: 24 ± 2 Hz at 32°C). Phase reset was associated with a transient enhancement of the synchronization of gamma activity recorded at distant (>1 mm) mEC sites, across which low coherence (>0.75) was observed before stimulation. This increase in synchronization, as measured by cross-correlation analysis, was restricted to a maximal period of 200 ms after either local mEC or CA1 afferent stimulation. The results provide direct evidence that synaptic activation can enhance the rhythmic synchronization of spatially remote, independently oscillating neuronal assemblies in the mEC through a mechanism of synaptically evoked phase reset. Dynamic functional grouping of oscillatory discharges across long distances in the mEC may underlie coding processes involved in the integration and storage of incoming information and thus may be important for the role of this region in memory processes. Hippocampus 2002;12:447,456. © 2002 Wiley-Liss, Inc. [source]


Oscillatory activity in parietal and dorsolateral prefrontal cortex during retention in visual short-term memory: Additive effects of spatial attention and memory load

HUMAN BRAIN MAPPING, Issue 10 2009
Stéphan Grimault
Abstract We used whole-head magnetoencephalography to study the representation of objects in visual short-term memory (VSTM) in the human brain. Subjects remembered the location and color of either two or four colored disks that were encoded from the left or right visual field (equal number of distractors in the other visual hemifield). The data were analyzed using time-frequency methods, which enabled us to discover a strong oscillatory activity in the 8,15 Hz band during the retention interval. The study of the alpha power variation revealed two types of responses, in different brain regions. The first was a decrease in alpha power in parietal cortex, contralateral to the stimuli, with no load effect. The second was an increase of alpha power in parietal and lateral prefrontal cortex, as memory load increased, but without interaction with the hemifield of the encoded stimuli. The absence of interaction between side of encoded stimuli and memory load suggests that these effects reflect distinct underlying mechanisms. A novel method to localize the neural generators of load-related oscillatory activity was devised, using cortically-constrained distributed source-localization methods. Some activations were found in the inferior intraparietal sulcus (IPS) and intraoccipital sulcus (IOS). Importantly, strong oscillatory activity was also found in dorsolateral prefrontal cortex (DLPFC). Alpha oscillatory activity in DLPFC was synchronized with the activity in parietal regions, suggesting that VSTM functions in the human brain may be implemented via a network that includes bilateral DLPFC and bilateral IOS/IPS as key nodes. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]


Dissociation between MEG alpha modulation and performance accuracy on visual working memory task in obsessive compulsive disorder

HUMAN BRAIN MAPPING, Issue 12 2007
Kristina T. Ciesielski
Abstract Oscillatory brain activity in the alpha band (8,13 Hz) is modulated by cognitive events. Such modulation is reflected in a decrease of alpha (event-related desynchronization; ERD) with high cognitive load, or an increase (event-related synchronization) with low cognitive demand or with active inhibition of distractors. We used magnetoencephalography to investigate the pattern of prefrontal and parieto-occipital alpha modulation related to two variants of visual working memory task (delayed matching-to-sample) with and without a distractor. We tested nonmedicated, nondepressed patients suffering obsessive-compulsive disorder (OCD), and pair-matched healthy controls. The level of event-related alpha as a function of time was estimated using the temporal-spectral evolution technique. The results in OCD patients indicated: (1) a lower level of prestimulus (reference) alpha when compared to controls, (2) a task-phase specific reduction in event-related alpha ERD in particular for delayed matching-to-sample task with distractor, (3) no significant correlations between the pattern of modulation in prefrontal and parietal-occipital alpha oscillatory activity. Despite showing an abnormally low alpha modulation, the OCD patients' performance accuracy was normal. The results suggest a relationship of alpha oscillations and the underlying thalamocortical network to etiology of OCD and an involvement of a compensatory mechanism related to effortful inhibition of extrinsic and intrinsic interference. Hum Brain Mapp 2007. © 2007 Wiley-Liss, Inc. [source]


Prediction of general mental ability based on neural oscillation measures of sleep

JOURNAL OF SLEEP RESEARCH, Issue 3 2005
RÓBERT BÓDIZS
Summary The usual assessment of general mental ability (or intelligence) is based on performance attained in reasoning and problem-solving tasks. Differences in general mental ability have been associated with event-related neural activity patterns of the wakeful working brain or physical, chemical and electrical brain features measured during wakeful resting conditions. Recent evidences suggest that specific sleep electroencephalogram oscillations are related to wakeful cognitive performances. Our aim is to reveal the relationship between non-rapid eye movement sleep-specific oscillations (the slow oscillation, delta activity, slow and fast sleep spindle density, the grouping of slow and fast sleep spindles) and general mental ability assessed by the Raven Progressive Matrices Test (RPMT). The grouping of fast sleep spindles by the cortical slow oscillation in the left frontopolar derivation (Fp1) as well as the density of fast sleep spindles over the right frontal area (Fp2, F4), correlated positively with general mental ability. Data from those selected electrodes that showed the high correlations with general mental ability explained almost 70% of interindividual variance in RPMT scores. Results suggest that individual differences in general mental ability are reflected in fast sleep spindle-related oscillatory activity measured over the frontal cortex. [source]


Local field potentials and oscillatory activity of the internal globus pallidus in myoclonus,dystonia

MOVEMENT DISORDERS, Issue 3 2007
Elisabeth M.J. Foncke MD
Abstract The pathophysiology of myoclonus,dystonia (M,D), an autosomal dominantly inherited movement disorder characterized by myoclonic jerks and dystonic contractions, is largely unknown. In the present study, local field potential (LFP) activities in the globus pallidus internus (GPi) from two genetically proven M,D patients are investigated. Coherence analysis between GPi LFP activity and electromyographic muscle activity (EMG) and synchronization of GPi neuronal activity using event-related spectral perturbation (ERSP) in a go,no-go paradigm were studied. Significant increased coherence in the 3 to 15 Hz frequency band was detected between GPi LFP activity and several muscles, with the LFP leading the muscles. The ERSP analysis revealed synchronization in the 3 to 15 Hz frequency band within the GPi before the imperative cue of the go,no-go task and desynchronization in the same band after the cue. The LFP recordings of the GPi in M,D show that the low-frequency band previously described in dystonia is also involved in the dystonia plus syndrome M,D. The 3 to 15 Hz synchronization in the go,no-go paradigm has not been described previously and may point to the existence of (myoclonus,)dystonia specific oscillatory activity in the GPi. © 2006 Movement Disorder Society [source]


Oscillations in the basal ganglia under normal conditions and in movement disorders

MOVEMENT DISORDERS, Issue 10 2006
Plamen Gatev MD
Abstract A substantial body of work within the last decade has demonstrated that there is a variety of oscillatory phenomena that occur in the basal ganglia and in associated regions of the thalamus and cortex. Most of the earlier studies focused on recordings in rodents and primates. More recently, significant advances have been made in this field of research through the analysis of basal ganglia field potentials recorded from implanted deep brain stimulation electrodes in the basal ganglia of human patients with Parkinson's disease and other disorders. It now appears that oscillatory activity may play a significant role in the pathogenesis of these diseases. The most significant finding is that in Parkinson's disease synchronized oscillatory activity in the 10- to 35-Hz band (often termed ",-band") is prevalent in the basal ganglia,thalamocortical circuits, and that such activity can be reduced by dopaminergic treatments. The entrainment of large portions of these circuits may disrupt information processing in them and may lead to parkinsonian akinesia (and perhaps tremor). Although less firmly established than the role of oscillations in movement disorders, oscillatory activities at higher frequencies may also be a component of normal basal ganglia physiology. © 2006 Movement Disorder Society [source]


The pathophysiology of tremor

MUSCLE AND NERVE, Issue 6 2001
Günther Deuschl MD
Abstract Tremor is defined as rhythmic oscillatory activity of body parts. Four physiological basic mechanisms for such oscillatory activity have been described: mechanical oscillations; oscillations based on reflexes; oscillations due to central neuronal pacemakers; and oscillations because of disturbed feedforward or feedback loops. New methodological approaches with animal models, positron emission tomography, and mathematical analysis of electromyographic and electroencephalographic signals have provided new insights into the mechanisms underlying specific forms of tremor. Physiological tremor is due to mechanical and central components. Psychogenic tremor is considered to depend on a clonus mechanism and is thus believed to be mediated by reflex mechanisms. Symptomatic palatal tremor is most likely due to rhythmic activity of the inferior olive, and there is much evidence that essential tremor is also generated within the olivocerebellar circuits. Orthostatic tremor is likely to originate in hitherto unidentified brainstem nuclei. Rest tremor of Parkinson's disease is probably generated in the basal ganglia loop, and dystonic tremor may also originate within the basal ganglia. Cerebellar tremor is at least in part caused by a disturbance of the cerebellar feedforward control of voluntary movements, and Holmes' tremor is due to the combination of the mechanisms producing parkinsonian and cerebellar tremor. Neuropathic tremor is believed to be caused by abnormally functioning reflex pathways and a wide variety of causes underlies toxic and drug-induced tremors. The understanding of the pathophysiology of tremor has made significant progress but many hypotheses are not yet based on sufficient data. Modern neurology needs to develop and test such hypotheses, because this is the only way to develop rational medical and surgical therapies. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 716,735, 2001 [source]