401
|
Miller KJ, Sorensen LB, Ojemann JG, den Nijs M. Power-law scaling in the brain surface electric potential. PLoS Comput Biol 2009; 5:e1000609. [PMID: 20019800 PMCID: PMC2787015 DOI: 10.1371/journal.pcbi.1000609] [Citation(s) in RCA: 452] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 11/12/2009] [Indexed: 11/25/2022] Open
Abstract
Recent studies have identified broadband phenomena in the electric potentials produced by the brain. We report the finding of power-law scaling in these signals using subdural electrocorticographic recordings from the surface of human cortex. The power spectral density (PSD) of the electric potential has the power-law form P(f ) approximately Af(-chi) from 80 to 500 Hz. This scaling index, chi = 4.0+/-0.1, is conserved across subjects, area in the cortex, and local neural activity levels. The shape of the PSD does not change with increases in local cortical activity, but the amplitude, A, increases. We observe a "knee" in the spectra at f(0) approximately 75 Hz, implying the existence of a characteristic time scale tau = (2pif(0))(-1) approximately 2 - 4ms. Below f(0), we explore two-power-law forms of the PSD, and demonstrate that there are activity-related fluctuations in the amplitude of a power-law process lying beneath the alpha/beta rhythms. Finally, we illustrate through simulation how, small-scale, simplified neuronal models could lead to these power-law observations. This suggests a new paradigm of non-oscillatory "asynchronous," scale-free, changes in cortical potentials, corresponding to changes in mean population-averaged firing rate, to complement the prevalent "synchronous" rhythm-based paradigm.
Collapse
Affiliation(s)
- Kai J Miller
- Department of Physics, University of Washington, Seattle, Washington, USA.
| | | | | | | |
Collapse
|
402
|
Muthukumaraswamy SD, Singh KD, Swettenham JB, Jones DK. Visual gamma oscillations and evoked responses: variability, repeatability and structural MRI correlates. Neuroimage 2009; 49:3349-57. [PMID: 19944770 DOI: 10.1016/j.neuroimage.2009.11.045] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 11/11/2009] [Accepted: 11/18/2009] [Indexed: 02/04/2023] Open
Abstract
There is increasing interest in the role gamma oscillations ( approximately 40 Hz) play in visual information processing. Despite this interest, and in contrast to the classically studied visual evoked potential, surprisingly little is known about the intra-individual repeatability of induced gamma oscillations. Similarly, little is known about inter-individual variability in terms of gamma oscillation frequency, bandwidth and amplitude with no extant normative data for these parameters. The purpose of the current study was therefore to examine the repeatability of visual gamma oscillations and to provide the first normative data on them. Our results demonstrate that evoked responses were highly repeatable across recording sessions whereas for induced visual gamma oscillations a large amount of inter-individual variability existed in terms of frequency, bandwidth and amplitude. However, these parameters and the general morphology of the gamma band response were stable within the same individuals for at least 4 weeks. The high degree of individual variability in gamma oscillations for gamma amplitude, bandwidth and frequency suggests that between-group studies on gamma oscillations will be difficult, requiring relatively large amounts of data to detect differences. However, the high degree of individual repeatability for gamma oscillation frequency, bandwidth and amplitude suggests that these dependent variables will be well suited for repeated-measure designs such as pharmacological studies. A number of individuals are described which show clear evoked responses yet a near absence of gamma oscillations and vice versa suggesting dissociations between the generative mechanisms of these responses. Our results also demonstrate that gamma frequency tends to decline with age and is positively correlated with the thickness of the pericalcarine cortex.
Collapse
|
403
|
Liu CC, Ohara S, Franaszczuk P, Zagzoog N, Gallagher M, Lenz FA. Painful stimuli evoke potentials recorded from the medial temporal lobe in humans. Neuroscience 2009; 165:1402-11. [PMID: 19925853 DOI: 10.1016/j.neuroscience.2009.11.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2009] [Revised: 11/09/2009] [Accepted: 11/10/2009] [Indexed: 10/20/2022]
Abstract
The role of human medial temporal structures in fear conditioning has led to the suggestion that neurons in these structures might respond to painful stimuli. We have now tested the hypothesis that recordings from these structures will demonstrate potentials related to the selective activation of cutaneous nociceptors by a painful laser stimulus (laser evoked potential, LEP) (Kenton B, Coger R, Crue B, Pinsky J, Friedman Y, Carmon A (1980) Neurosci Lett 17:301-306). Recordings were carried out through electrodes implanted bilaterally in these structures for the investigation of intractable epilepsy. Reproducible LEPs were commonly recorded both bilaterally and unilaterally, while LEPs were recorded at contacts on the left (9/14, P=0.257) as commonly as on the right (5/14), independent of the hand stimulated. Along electrodes traversing the amygdala the majority of LEPs were recorded from dorsal contacts near the central nucleus of the amygdala and the nucleus basalis. Stimulus evoked changes in theta activity were observed at contacts on the right at which isolated early negative LEPs (N2*) responses could be recorded. Contacts at which LEPs could be recorded were as commonly located in medial temporal structures with evidence of seizure activity as on those without. These results demonstrate the presence of pain-related inputs to the medial temporal lobe where they may be involved in associative learning to produce anxiety and disability related to painful stimuli.
Collapse
Affiliation(s)
- C C Liu
- Department of Neurosurgery, Meyer 5-181, Johns Hopkins University, Baltimore, MD 21287-7713, USA
| | | | | | | | | | | |
Collapse
|
404
|
Automated electrocorticographic electrode localization on individually rendered brain surfaces. J Neurosci Methods 2009; 185:293-8. [PMID: 19836416 DOI: 10.1016/j.jneumeth.2009.10.005] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 10/06/2009] [Accepted: 10/07/2009] [Indexed: 11/22/2022]
Abstract
Brain surface electrocorticographic (ECoG) recordings can investigate human brain electrophysiology at the cortical surface with exceptionally high signal to noise ratio and spatio-temporal resolution. To be able to use the high spatial resolution of ECoG for accurate brain function mapping and neurophysiology studies, the exact location of the ECoG electrodes on the brain surface should be known. Several issues complicate robust localization: surgical photographs of the electrode array made after implantation are often incomplete because the grids may be moved underneath the skull, beyond the exposed area. Computed tomography (CT) scans made after implantation will clearly localize electrodes, but the effects of surgical intervention may cause the exposed brain to move away from the skull and assume an unpredictable shape (the so-called brain shift). First, we present a method based on a preoperative magnetic resonance imaging (MRI) coregistered with a post-implantation CT scan to localize the electrodes and that automatically corrects for the brain shift by projecting the electrodes to the surface of the cortex. The calculated electrode positions are visualized on the individual subjects brain surface rendering. Second, the method was validated by comparison with surgical photographs, finding a median difference between photographic and calculated electrode centers-of-mass of only 2.6mm, across 6 subjects. Third, to illustrate its utility we demonstrate how functional MRI and ECoG findings in the same subject may be directly compared in a simple motor movement experiment even when electrodes are not visible in the craniotomy.
Collapse
|
405
|
Yuan H, Liu T, Szarkowski R, Rios C, Ashe J, He B. Negative covariation between task-related responses in alpha/beta-band activity and BOLD in human sensorimotor cortex: an EEG and fMRI study of motor imagery and movements. Neuroimage 2009; 49:2596-606. [PMID: 19850134 DOI: 10.1016/j.neuroimage.2009.10.028] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 10/11/2009] [Accepted: 10/12/2009] [Indexed: 11/29/2022] Open
Abstract
Similar to the occipital alpha rhythm, electroencephalographic (EEG) signals in the alpha- and beta-frequency bands can be suppressed by movement or motor imagery and have thus been thought to represent the "idling state" of the sensorimotor cortex. A negative correlation between spontaneous alpha EEG and blood-oxygen-level-dependent (BOLD) signals has been reported in combined EEG and fMRI (functional Magnetic Resonance Imaging) experiments when subjects stayed at the resting state or alternated between the resting state and a task. However, the precise nature of the task-induced alpha modulation remains elusive. It was not clear whether alpha/beta rhythm suppressions may co-vary with BOLD when conducting tasks involving varying activations of the cortex. Here, we quantified the task-evoked responses of BOLD and alpha/beta-band power of EEG directly in the cortical source domain, by using source imaging technology, and examined their covariation across task conditions in a mixed block and event-related design. In this study, 13 subjects performed tasks of right-hand, right-foot or left-hand movement and motor imagery when EEG and fMRI data were separately collected. Task-induced increase of BOLD signal and decrease of EEG amplitudes in alpha and beta bands were shown to be co-localized at the somatotopic sensorimotor cortex. At the corresponding regions, the reciprocal changes of the two signals co-varied in the magnitudes across imagination and movement conditions. The spatial correspondence and negative covariation between the two measurements were further shown to exist at somatotopic brain regions associated with different body parts. These results suggest an inverse functional coupling relationship between task-induced changes of BOLD and low-frequency EEG signals.
Collapse
Affiliation(s)
- Han Yuan
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | | | | | | | | | | |
Collapse
|
406
|
Soto JLP, Pantazis D, Jerbi K, Lachaux JP, Garnero L, Leahy RM. Detection of event-related modulations of oscillatory brain activity with multivariate statistical analysis of MEG data. Hum Brain Mapp 2009; 30:1922-34. [PMID: 19378281 DOI: 10.1002/hbm.20765] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
We describe a method to detect brain activation in cortically constrained maps of current density computed from magnetoencephalography (MEG) data using multivariate statistical inference. We apply time-frequency (wavelet) analysis to individual epochs to produce dynamic images of brain signal power on the cerebral cortex in multiple time-frequency bands. We form vector observations by concatenating the power in each frequency band, and fit them into separate multivariate linear models for each time band and cortical location with experimental conditions as predictor variables. The resulting Roy's maximum root statistic maps are thresholded for significance using permutation tests and the maximum statistic approach. A source is considered significant if it exceeds a statistical threshold, which is chosen to control the familywise error rate, or the probability of at least one false positive, across the cortical surface. We compare and evaluate the multivariate approach with existing univariate approaches to time-frequency MEG signal analysis, both on simulated data and experimental data from an MEG visuomotor task study. Our results indicate that the multivariate method is more powerful than the univariate approach in detecting experimental effects when correlations exist between power across frequency bands. We further describe protected F-tests and linear discriminant analysis to identify individual frequencies that contribute significantly to experimental effects.
Collapse
Affiliation(s)
- Juan L P Soto
- Signal and Image Processing Institute, University of Southern California, 3740 McClintock Ave., Los Angeles, CA 90089-2564, USA
| | | | | | | | | | | |
Collapse
|
407
|
Jerbi K, Ossandón T, Hamamé CM, Senova S, Dalal SS, Jung J, Minotti L, Bertrand O, Berthoz A, Kahane P, Lachaux JP. Task-related gamma-band dynamics from an intracerebral perspective: review and implications for surface EEG and MEG. Hum Brain Mapp 2009; 30:1758-71. [PMID: 19343801 DOI: 10.1002/hbm.20750] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Although non-invasive techniques provide functional activation maps at ever-growing spatio-temporal precision, invasive recordings offer a unique opportunity for direct investigations of the fine-scale properties of neural mechanisms in focal neuronal populations. In this review we provide an overview of the field of intracranial Electroencephalography (iEEG) and discuss its strengths and limitations and its relationship to non-invasive brain mapping techniques. We discuss the characteristics of invasive data acquired from implanted epilepsy patients using stereotactic-electroencephalography (SEEG) and electrocorticography (ECoG) and the use of spectral analysis to reveal task-related modulations in multiple frequency components. Increasing evidence suggests that gamma-band activity (>40 Hz) might be a particularly efficient index for functional mapping. Moreover, the detection of high gamma activity may play a crucial role in bridging the gap between electrophysiology and functional imaging studies as well as in linking animal and human data. The present review also describes recent advances in real-time invasive detection of oscillatory modulations (including gamma activity) in humans. Furthermore, the implications of intracerebral findings on future non-invasive studies are discussed.
Collapse
Affiliation(s)
- Karim Jerbi
- INSERM U821, Brain Dynamics and Cognition; Université Claude Bernard, Lyon 1, Lyon, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
408
|
Neural representations of individual stimuli in humans revealed by gamma-band electrocorticographic activity. J Neurosci 2009; 29:10203-14. [PMID: 19692595 DOI: 10.1523/jneurosci.2187-09.2009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A fundamental question in neuroscience concerns how the human brain represents perceptual and conceptual information. Traditionally, researchers probed this issue by identifying single neurons that increased their firing rate when an animal encountered certain stimuli. Here we provide evidence of a complementary scheme in which gamma-band (25-128 Hz) electrocorticographic (ECoG) activity -- a phenomenon involving large groups of neurons -- encodes the active cognitive representation. We analyzed intracranial brain recordings from neurosurgical patients while they studied lists of visually presented letters and found that the amplitude of gamma-band activity encoded the identity of the current letter. These letter-specific patterns occurred during periods of overall increased gamma amplitude and were linked to the phase of simultaneous theta (4-8 Hz) oscillations. In occipital cortex, these patterns sometimes reflected the shape of the viewed letter, but, in other brain regions, this phenomenon was not related to letter form. Our findings show that gamma-band activity encodes a range of perceptual and conceptual information, suggesting that ECoG recordings can reveal neural correlates of specific human cognitive representations.
Collapse
|
409
|
Buildup of choice-predictive activity in human motor cortex during perceptual decision making. Curr Biol 2009; 19:1581-5. [PMID: 19747828 DOI: 10.1016/j.cub.2009.07.066] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/28/2009] [Accepted: 07/30/2009] [Indexed: 11/22/2022]
Abstract
Simple perceptual decisions are ideally suited for studying the sensorimotor transformations underlying flexible behavior. During perceptual detection, a noisy sensory signal is converted into a behavioral report of the presence or absence of a perceptual experience. Here, we used magnetoencephalography (MEG) to link the dynamics of neural population activity in human motor cortex to perceptual choices in a "yes/no" visual motion detection task. We found that (1) motor response-selective MEG activity in the "gamma" (64-100 Hz) and "beta" (12-36 Hz) frequency ranges predicted subjects' choices several seconds before their overt manual response; (2) this choice-predictive activity built up gradually during stimulus viewing toward both "yes" and "no" choices; and (3) the choice-predictive activity in motor cortex reflected the temporal integral of gamma-band activity in motion-sensitive area MT during stimulus viewing. Because gamma-band activity in MT reflects visual motion strength, these findings suggest that, during motion detection, motor plans for both "yes" and "no" choices result from continuously accumulating sensory evidence. We conclude that frequency-specific neural population activity at the cortical output stage of sensorimotor pathways provides a window into the mechanisms underlying perceptual decisions.
Collapse
|
410
|
Brugge JF, Nourski KV, Oya H, Reale RA, Kawasaki H, Steinschneider M, Howard MA. Coding of repetitive transients by auditory cortex on Heschl's gyrus. J Neurophysiol 2009; 102:2358-74. [PMID: 19675285 DOI: 10.1152/jn.91346.2008] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The capacity of auditory cortex on Heschl's gyrus (HG) to encode repetitive transients was studied in human patients undergoing surgical evaluation for medically intractable epilepsy. Multicontact depth electrodes were chronically implanted in gray matter of HG. Bilaterally presented stimuli were click trains varying in rate from 4 to 200 Hz. Averaged evoked potentials (AEPs) and event-related band power (ERBP), computed from responses at each of 14 recording sites, identified two auditory fields. A core field, which occupies posteromedial HG, was characterized by a robust polyphasic AEP on which could be superimposed a frequency following response (FFR). The FFR was prominent at click rates below approximately 50 Hz, decreased rapidly as click rate was increased, but could reliably be detected at click rates as high as 200 Hz. These data are strikingly similar to those obtained by others in the monkey under essentially the same stimulus conditions, indicating that mechanisms underlying temporal processing in the auditory core may be highly conserved across primate species. ERBP, which reflects increases or decreases of both phase-locked and non-phase-locked power within given frequency bands, showed stimulus-related increases in gamma band frequencies as high as 250 Hz. The AEPs recorded in a belt field anterolateral to the core were typically of low amplitude, showing little or no evidence of short-latency waves or an FFR, even at the lowest click rates used. The non-phase-locked component of the response extracted from the ERBP showed a robust, long-latency response occurring here in response to the highest click rates in the series.
Collapse
Affiliation(s)
- John F Brugge
- Department of Neurosurgery, University of Iowa, Iowa City, Iowa, USA.
| | | | | | | | | | | | | |
Collapse
|
411
|
Waldert S, Pistohl T, Braun C, Ball T, Aertsen A, Mehring C. A review on directional information in neural signals for brain-machine interfaces. ACTA ACUST UNITED AC 2009; 103:244-54. [PMID: 19665554 DOI: 10.1016/j.jphysparis.2009.08.007] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brain-machine interfaces (BMIs) can be characterized by the technique used to measure brain activity and by the way different brain signals are translated into commands that control an effector. We give an overview of different approaches and focus on a particular BMI approach: the movement of an artificial effector (e.g. arm prosthesis to the right) by those motor cortical signals that control the equivalent movement of a corresponding body part (e.g. arm movement to the right). This approach has been successfully applied in monkeys and humans by accurately extracting parameters of movements from the spiking activity of multiple single-units. Here, we review recent findings showing that analog neuronal population signals, ranging from intracortical local field potentials over epicortical ECoG to non-invasive EEG and MEG, can also be used to decode movement direction and continuous movement trajectories. Therefore, these signals might provide additional or alternative control for this BMI approach, with possible advantages due to reduced invasiveness.
Collapse
Affiliation(s)
- Stephan Waldert
- Faculty of Biology, Albert-Ludwigs-University, Hauptstrasse 1, Freiburg, Germany.
| | | | | | | | | | | |
Collapse
|
412
|
Brunner P, Ritaccio AL, Lynch TM, Emrich JF, Wilson JA, Williams JC, Aarnoutse EJ, Ramsey NF, Leuthardt EC, Bischof H, Schalk G. A practical procedure for real-time functional mapping of eloquent cortex using electrocorticographic signals in humans. Epilepsy Behav 2009; 15:278-86. [PMID: 19366638 PMCID: PMC2754703 DOI: 10.1016/j.yebeh.2009.04.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/31/2009] [Accepted: 04/01/2009] [Indexed: 10/20/2022]
Abstract
Functional mapping of eloquent cortex is often necessary prior to invasive brain surgery, but current techniques that derive this mapping have important limitations. In this article, we demonstrate the first comprehensive evaluation of a rapid, robust, and practical mapping system that uses passive recordings of electrocorticographic signals. This mapping procedure is based on the BCI2000 and SIGFRIED technologies that we have been developing over the past several years. In our study, we evaluated 10 patients with epilepsy from four different institutions and compared the results of our procedure with the results derived using electrical cortical stimulation (ECS) mapping. The results show that our procedure derives a functional motor cortical map in only a few minutes. They also show a substantial concurrence with the results derived using ECS mapping. Specifically, compared with ECS maps, a next-neighbor evaluation showed no false negatives, and only 0.46 and 1.10% false positives for hand and tongue maps, respectively. In summary, we demonstrate the first comprehensive evaluation of a practical and robust mapping procedure that could become a new tool for planning of invasive brain surgeries.
Collapse
Affiliation(s)
- Peter Brunner
- Brain–Computer Interface R&D Program, Wadsworth Center, New York State Department of Health, Albany, NY, USA
- Institute for Computer Graphics and Vision, Graz University of Technology, Graz, Austria
| | | | - Timothy M. Lynch
- Department of Neurology, Albany Medical College, Albany, NY, USA
| | - Joseph F. Emrich
- Department of Neurosurgery, Albany Medical College, Albany, NY, USA
| | - J. Adam Wilson
- Department of Biomedical Engineering, University of Wisconsin at Madison, Madison, WI, USA
| | - Justin C. Williams
- Department of Biomedical Engineering, University of Wisconsin at Madison, Madison, WI, USA
| | - Erik J. Aarnoutse
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands
| | - Nick F. Ramsey
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands
| | - Eric C. Leuthardt
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Horst Bischof
- Institute for Computer Graphics and Vision, Graz University of Technology, Graz, Austria
| | - Gerwin Schalk
- Brain–Computer Interface R&D Program, Wadsworth Center, New York State Department of Health, Albany, NY, USA
- Department of Neurology, Albany Medical College, Albany, NY, USA
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA
- Corresponding author. Brain-Computer Interface R&D Program, New York State Department of Health, C650 Empire State Plaza, Albany, New York 12201, USA, Fax: +1 518 486 4910. (Gerwin Schalk)
| |
Collapse
|
413
|
Scherer R, Zanos SP, Miller KJ, Rao RPN, Ojemann JG. Classification of contralateral and ipsilateral finger movements for electrocorticographic brain-computer interfaces. Neurosurg Focus 2009; 27:E12. [DOI: 10.3171/2009.4.focus0981] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Electrocorticography (ECoG) offers a powerful and versatile platform for developing brain-computer interfaces; it avoids the risks of brain-invasive methods such as intracortical implants while providing significantly higher signal-to-noise ratio than noninvasive techniques such as electroencephalography. The authors demonstrate that both contra- and ipsilateral finger movements can be discriminated from ECoG signals recorded from a single brain hemisphere. The ECoG activation patterns over sensorimotor areas for contra- and ipsilateral movements were found to overlap to a large degree in the recorded hemisphere. Ipsilateral movements, however, produced less pronounced activity compared with contralateral movements. The authors also found that single-trial classification of movements could be improved by selecting patient-specific frequency components in high-frequency bands (> 50 Hz). Their discovery that ipsilateral hand movements can be discriminated from ECoG signals from a single hemisphere has important implications for neurorehabilitation, suggesting in particular the possibility of regaining ipsilateral movement control using signals from an intact hemisphere after damage to the other hemisphere.
Collapse
|
414
|
Ritter P, Moosmann M, Villringer A. Rolandic alpha and beta EEG rhythms' strengths are inversely related to fMRI-BOLD signal in primary somatosensory and motor cortex. Hum Brain Mapp 2009; 30:1168-87. [PMID: 18465747 DOI: 10.1002/hbm.20585] [Citation(s) in RCA: 291] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Similar to the posterior alpha rhythm, pericentral (Rolandic) EEG rhythms in the alpha and beta frequency range are referred to as "idle rhythms" indicating a "resting state" of the respective system. The precise function of these rhythms is not clear. We used simultaneous EEG-fMRI during a bimanual motor task to localize brain areas involved in Rolandic alpha and beta EEG rhythms. The identification of these rhythms in the MR environment was achieved by a blind source separation algorithm. Rhythm "strength", i.e. spectral power determined by wavelet analysis, inversely correlated most strongly with the fMRI-BOLD signal in the postcentral cortex for the Rolandic alpha (mu) rhythm and in the precentral cortex for the Rolandic beta rhythm. FMRI correlates of Rolandic alpha and beta rhythms were distinct from those associated with the posterior "classical" alpha rhythm, which correlated inversely with the BOLD signal in the occipital cortex. An inverse correlation with the BOLD signal in the respective sensory area seems to be a general feature of "idle rhythms".
Collapse
Affiliation(s)
- Petra Ritter
- Berlin NeuroImaging Center and Charité, Universitätsmedizin Berlin, Germany.
| | | | | |
Collapse
|
415
|
Zanos S, Miller KJ, Ojemann JG. Electrocorticographic spectral changes associated with ipsilateral individual finger and whole hand movement. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:5939-42. [PMID: 19164072 DOI: 10.1109/iembs.2008.4650569] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The study of the human sensorimotor (SM) cortex activations associated with hand motor movement is central to the design of efficient and clinically useful brain-computer interfaces. Whereas the electrocorticographic (ECoG) signatures of contralateral hand movement have been studied in detail, those of ipsilateral hand and individual finger movements have not been characterized. We studied the low (8-32 Hz) and high-frequency (76-100 Hz) SM cortical ECoG spectral changes associated with contralateral and ipsilateral whole hand and individual finger movement and assessed their discriminability. We find that ipsilateral movement is associated with widespread decreases in the low-frequency band (LFB) and more focal increases in the high-frequency band (HFB). The HFB component discriminates between ipsilateral and contralateral movement-associated activations, in contrast to the LFB. The HFB also discriminates between thumb and index finger movement-associated activations, for both the contralateral and the ipsilateral case, whereas the LFB does not. This is the first published report of a discriminable ipsilateral motor signal, with important implications in the use of brain-computer interfaces in hemiplegic patients.
Collapse
Affiliation(s)
- Stavros Zanos
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, USA.
| | | | | |
Collapse
|
416
|
Dalal SS, Baillet S, Adam C, Ducorps A, Schwartz D, Jerbi K, Bertrand O, Garnero L, Martinerie J, Lachaux JP. Simultaneous MEG and intracranial EEG recordings during attentive reading. Neuroimage 2009; 45:1289-304. [DOI: 10.1016/j.neuroimage.2009.01.017] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 12/23/2008] [Accepted: 01/09/2009] [Indexed: 10/21/2022] Open
|
417
|
Decoupling the cortical power spectrum reveals real-time representation of individual finger movements in humans. J Neurosci 2009; 29:3132-7. [PMID: 19279250 DOI: 10.1523/jneurosci.5506-08.2009] [Citation(s) in RCA: 252] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During active movement the electric potentials measured from the surface of the motor cortex exhibit consistent modulation, revealing two distinguishable processes in the power spectrum. At frequencies <40 Hz, narrow-band power decreases occur with movement over widely distributed cortical areas, while at higher frequencies there are spatially more focal power increases. These high-frequency changes have commonly been assumed to reflect synchronous rhythms, analogous to lower-frequency phenomena, but it has recently been proposed that they reflect a broad-band spectral change across the entire spectrum, which could be obscured by synchronous rhythms at low frequencies. In 10 human subjects performing a finger movement task, we demonstrate that a principal component type of decomposition can naively separate low-frequency narrow-band rhythms from an asynchronous, broad-spectral, change at all frequencies between 5 and 200 Hz. This broad-spectral change exhibited spatially discrete representation for individual fingers and reproduced the temporal movement trajectories of different individual fingers.
Collapse
|
418
|
Nonlinear phase-phase cross-frequency coupling mediates communication between distant sites in human neocortex. J Neurosci 2009; 29:426-35. [PMID: 19144842 DOI: 10.1523/jneurosci.3688-08.2009] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Human cognition is thought to be mediated by large-scale interactions between distant sites in the neocortex. Synchronization between different cortical areas has been suggested as one possible mechanism for corticocortical interaction. Here, we report robust, directional cross-frequency synchronization between distant sensorimotor sites in human neocortex during a movement task. In four subjects, electrocorticographic recordings from the cortical surface revealed a low-frequency rhythm (10-13 Hz) that combined with a higher frequency (77-82 Hz) in a ventral region of the premotor cortex to produce a third rhythm at the sum of these two frequencies in a distant motor site. Such cross-frequency coupling implies a nonlinear interaction between these cortical sites. These findings demonstrate that task-specific, phase-phase coupling can support communication between distant areas of the human neocortex.
Collapse
|
419
|
Yao B, Liu JZ, Brown RW, Sahgal V, Yue GH. Nonlinear features of surface EEG showing systematic brain signal adaptations with muscle force and fatigue. Brain Res 2009; 1272:89-98. [PMID: 19332036 DOI: 10.1016/j.brainres.2009.03.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 03/17/2009] [Accepted: 03/17/2009] [Indexed: 11/25/2022]
Abstract
Nonlinear dynamics has been introduced to the analysis of biological data and increasingly recognized to be functionally relevant. The purpose of this study was to examine chaotic properties of human scalp EEG signals associated with voluntary motor tasks using the largest Lyapunov exponent (L1). 64-channel scalp EEG data were recorded from eight healthy subjects in two tasks: (1) intermittent handgrip contractions at 20, 40, 60, and 80% of maximal voluntary contraction (MVC) with 20 trials at each level. No significant fatigue were induced; (2) intermittent handgrip MVCs (100 trials) that resulted in significant fatigue. The L1 values of all EEG channels were calculated in each trial first then averaged across the 20 trials at each force level (Task 1) or over each of the 5-trial blocks (Task 2) before the group means were obtained. A multivariate statistical model was used to examine the effect of force and fatigue on L1. L1 values were greater with higher force (Task 1), and decreased significantly with fatigue (Task 2). The L1 of the EEG signals changes systematically and correlates significantly with muscle force and fatigue. The results suggest that nonlinear chaotic index L1 may serve as a quantitative measure for motor control-related cortical signal adaptations.
Collapse
Affiliation(s)
- Bing Yao
- Laboratory of Functional Magnetic Imaging, National Institute of Neurological Disorders and Strokes, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | | | | | | | | |
Collapse
|
420
|
Urrestarazu E, Iriarte J, Alegre M, Clavero P, Rodríguez-Oroz MC, Guridi J, Obeso JA, Artieda J. Beta activity in the subthalamic nucleus during sleep in patients with Parkinson's disease. Mov Disord 2009; 24:254-60. [DOI: 10.1002/mds.22351] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
421
|
Advanced neurotechnologies for chronic neural interfaces: new horizons and clinical opportunities. J Neurosci 2009; 28:11830-8. [PMID: 19005048 DOI: 10.1523/jneurosci.3879-08.2008] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
422
|
Ball T, Schulze-Bonhage A, Aertsen A, Mehring C. Differential representation of arm movement direction in relation to cortical anatomy and function. J Neural Eng 2009; 6:016006. [DOI: 10.1088/1741-2560/6/1/016006] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
423
|
Yanagisawa T, Hirata M, Saitoh Y, Kato A, Shibuya D, Kamitani Y, Yoshimine T. Neural decoding using gyral and intrasulcal electrocorticograms. Neuroimage 2009; 45:1099-106. [PMID: 19349227 DOI: 10.1016/j.neuroimage.2008.12.069] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2008] [Revised: 12/03/2008] [Accepted: 12/31/2008] [Indexed: 10/21/2022] Open
Abstract
Electrocorticography of the primary motor cortex (M1) is a promising tool for controlling a brain-computer interface (BCI). Electrocorticograms (ECoG) of the human M1 within the central sulcus (intrasulcal ECoG) have been rarely examined. In order to evaluate the usefulness of intrasulcal ECoG for BCI, we examined patients with subdural electrodes placed temporarily inside the central sulcus and over the sensorimotor cortex (gyral ECoG). Five patients were asked to perform or imagine two or three classes of simple upper limb movements. Univariate statistical analysis of the results revealed that the intrasulcal ECoG on M1 showed significant variability across movement classes. A support vector machine was used for classification of single-trial ECoG signals to infer movement class (neural decoding). The movement classes were predicted with 80-90% accuracy (chance level: 33% or 50%). To reveal the relative importance of anatomical areas for neural decoding, the decoding performance was compared between gyral and intrasulcal ECoGs. The intrasulcal ECoG on the motor bank showed higher performance than the equally-sized gyral ECoG or the intrasulcal ECoG on the sensory bank. Analysis using a short time window revealed that movement class could be decoded even before movement onset. These results suggest the usefulness of intrasulcal ECoG on M1 to infer upper limb movements and present a promising application for a practical BCI system.
Collapse
Affiliation(s)
- Takufumi Yanagisawa
- Department of Neurosurgery, Osaka University Medical School, Osaka 565-0871, Japan
| | | | | | | | | | | | | |
Collapse
|
424
|
Rouse AG, Moran DW. Neural adaptation of epidural electrocorticographic (EECoG) signals during closed-loop brain computer interface (BCI) tasks. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:5514-5517. [PMID: 19964124 DOI: 10.1109/iembs.2009.5333180] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Invasive BCI studies have classically relied on actual or imagined movements to train their neural decoding algorithms. In this study, non-human primates were required to perform a 2D BCI task using epidural microECoG recordings. The decoding weights and cortical locations of the electrodes used for control were randomly chosen and fixed for a series of daily recording sessions for five days. Over a period of one week, the subjects learned to accurately control a 2D computer cursor through neural adaptation of microECoG signals over "cortical control columns" having diameters on a the order of a few mm. These results suggest that the spatial resolution of microECoG recordings can be increased via neural plasticity.
Collapse
Affiliation(s)
- Adam G Rouse
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA.
| | | |
Collapse
|
425
|
|
426
|
Korzeniewska A, Crainiceanu CM, Kuś R, Franaszczuk PJ, Crone NE. Dynamics of event-related causality in brain electrical activity. Hum Brain Mapp 2008; 29:1170-92. [PMID: 17712784 PMCID: PMC6870676 DOI: 10.1002/hbm.20458] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A new method (Event-Related Causality, ERC) is proposed for the investigation of functional interactions between brain regions during cognitive processing. ERC estimates the direction, intensity, spectral content, and temporal course of brain activity propagation within a cortical network. ERC is based upon the short-time directed transfer function (SDTF), which is measured in short EEG epochs during multiple trials of a cognitive task, as well as the direct directed transfer function (dDTF), which distinguishes direct interactions between brain regions from indirect interactions via brain regions. ERC uses new statistical methods for comparing estimates of causal interactions during prestimulus "baseline" epochs and during poststimulus "activated" epochs in order to estimate event-related increases and decreases in the functional interactions between cortical network components during cognitive tasks. The utility of the ERC approach is demonstrated through its application to human electrocorticographic recordings (ECoG) of a simple language task. ERC analyses of these ECoG recordings reveal frequency-dependent interactions, particularly in high gamma (>60 Hz) frequencies, between brain regions known to participate in the recorded language task, and the temporal evolution of these interactions is consistent with the putative processing stages of this task. The method may be a useful tool for investigating the dynamics of causal interactions between various brain regions during cognitive task performance.
Collapse
Affiliation(s)
- Anna Korzeniewska
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Meyer 2‐147, Baltimore, Maryland
| | - Ciprian M. Crainiceanu
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., E3636, Baltimore, Maryland
| | - Rafał Kuś
- Department of Biomedical Physics, Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00‐681 Warsaw, Poland
| | - Piotr J. Franaszczuk
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Meyer 2‐147, Baltimore, Maryland
| | - Nathan E. Crone
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Meyer 2‐147, Baltimore, Maryland
| |
Collapse
|
427
|
Siegel M, Donner TH, Oostenveld R, Fries P, Engel AK. Neuronal Synchronization along the Dorsal Visual Pathway Reflects the Focus of Spatial Attention. Neuron 2008; 60:709-19. [DOI: 10.1016/j.neuron.2008.09.010] [Citation(s) in RCA: 328] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 09/04/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
|
428
|
Wisneski KJ, Anderson N, Schalk G, Smyth M, Moran D, Leuthardt EC. Unique cortical physiology associated with ipsilateral hand movements and neuroprosthetic implications. Stroke 2008; 39:3351-9. [PMID: 18927456 DOI: 10.1161/strokeaha.108.518175] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Brain computer interfaces (BCIs) offer little direct benefit to patients with hemispheric stroke because current platforms rely on signals derived from the contralateral motor cortex (the same region injured by the stroke). For BCIs to assist hemiparetic patients, the implant must use unaffected cortex ipsilateral to the affected limb. This requires the identification of distinct electrophysiological features from the motor cortex associated with ipsilateral hand movements. METHODS In this study we studied 6 patients undergoing temporary placement of intracranial electrode arrays. Electrocorticographic (ECoG) signals were recorded while the subjects engaged in specific ipsilateral or contralateral hand motor tasks. Spectral changes were identified with regards to frequency, location, and timing. RESULTS Ipsilateral hand movements were associated with electrophysiological changes that occur in lower frequency spectra, at distinct anatomic locations, and earlier than changes associated with contralateral hand movements. In a subset of 3 patients, features specific to ipsilateral and contralateral hand movements were used to control a cursor on a screen in real time. In ipsilateral derived control this was optimal with lower frequency spectra. CONCLUSIONS There are distinctive cortical electrophysiological features associated with ipsilateral movements which can be used for device control. These findings have implications for patients with hemispheric stroke because they offer a potential methodology for which a single hemisphere can be used to enhance the function of a stroke induced hemiparesis.
Collapse
Affiliation(s)
- Kimberly J Wisneski
- Department of Biomedical Engineering, Washington University in St Louis, MO, USA.
| | | | | | | | | | | |
Collapse
|
429
|
Greenspan JD, Ohara S, Franaszczuk P, Veldhuijzen DS, Lenz FA. Cold stimuli evoke potentials that can be recorded directly from parasylvian cortex in humans. J Neurophysiol 2008; 100:2282-6. [PMID: 18579655 PMCID: PMC2576208 DOI: 10.1152/jn.90564.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 06/20/2008] [Indexed: 11/22/2022] Open
Abstract
Anatomic, imaging, and lesion studies suggest that insular or parietal opercular cortical structures mediate the sensation of nonpainful cold. We have now tested the hypothesis that cold stimuli evoke electrical responses from these cortical structures in humans. We recorded the response to cold stimuli from electrodes implanted directly over parasylvian cortex for the investigation of intractable seizures. The results demonstrate that slow potentials can be evoked consistently over structures adjacent to the sylvian fissure in response to nonpainful cold. The polarity of these cold evoked potentials (EPs) for electrodes above the sylvian fissure is opposite to those below. These results suggest that the generator of cold EPs is close to the sylvian fissure in the parietal operculum or insula.
Collapse
Affiliation(s)
- J D Greenspan
- Department of Neurosurgery, Johns Hopkins Hospital, and Department of Biomedical Sciences, University of Maryland Dental School, Meyer Building 8-181, 600 North Wolfe Street, Baltimore, MD 21287-7713, USA
| | | | | | | | | |
Collapse
|
430
|
Nagarajan S, Kirsch H, Lin P, Findlay A, Honma S, Berger MS. Preoperative localization of hand motor cortex by adaptive spatial filtering of magnetoencephalography data. J Neurosurg 2008; 109:228-37. [PMID: 18671634 DOI: 10.3171/jns/2008/109/8/0228] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The goal of this study was to examine the sensitivity and specificity in preoperative localization of hand motor cortex by imaging regional event-related desynchronization (ERD) of brainwaves in the β frequency band (15–25 Hz) involved in self-paced movement.
Methods
Using magnetoencephalography (MEG), the authors measured ERD that occurred before self-paced unilateral index finger flexion in 66 patients with brain tumors, epilepsy, and arteriovenous malformations.
Results
The authors applied an adaptive spatial filtering algorithm to MEG data and found that peaks of the tomographic distribution of β-band ERD sources reliably localized hand motor cortex compared with electrical cortical stimulation. They also observed high specificity in estimating contralateral hand motor cortical representations relative to somatosensory cortex. Neither presence nor location of tumor changed the qualitative or quantitative location of motor cortex relative to somatosensory cortex.
Conclusions
An imaging protocol using ERD obtained by adaptive spatial filtering of MEG data can be used for extremely reliable preoperative localization of hand motor cortex.
Collapse
Affiliation(s)
| | | | - Peter Lin
- 1Biomagnetic Imaging Laboratory, Department of Radiology, and
- 3Department of Neurology, Stanford University School of Medicine, Stanford, California
| | - Anne Findlay
- 1Biomagnetic Imaging Laboratory, Department of Radiology, and
| | - Susanne Honma
- 1Biomagnetic Imaging Laboratory, Department of Radiology, and
| | | |
Collapse
|
431
|
Real-time detection of event-related brain activity. Neuroimage 2008; 43:245-9. [PMID: 18718544 DOI: 10.1016/j.neuroimage.2008.07.037] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 06/27/2008] [Accepted: 07/16/2008] [Indexed: 11/22/2022] Open
Abstract
The complexity and inter-individual variation of brain signals impedes real-time detection of events in raw signals. To convert these complex signals into results that can be readily understood, current approaches usually apply statistical methods to data from known conditions after all data have been collected. The capability to provide meaningful visualization of complex brain signals without the requirement to initially collect data from all conditions would provide a new tool, essentially a new imaging technique, that would open up new avenues for the study of brain function. Here we show that a new analysis approach, called SIGFRIED, can overcome this serious limitation of current methods. SIGFRIED can visualize brain signal changes without requiring prior data collection from all conditions. This capacity is particularly well suited to applications in which comprehensive prior data collection is impossible or impractical, such as intraoperative localization of cortical function or detection of epileptic seizures.
Collapse
|
432
|
Kaiser J, Rahm B, Lutzenberger W. Direct contrasts between experimental conditions may yield more focal oscillatory activations than comparing pre- versus post-stimulus responses. Brain Res 2008; 1235:63-73. [PMID: 18602906 DOI: 10.1016/j.brainres.2008.06.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 05/21/2008] [Accepted: 06/10/2008] [Indexed: 11/26/2022]
Abstract
Contrasting electro- or magnetoencephalographic oscillatory responses to sensory stimuli with a pre-stimulation baseline commonly yields spectrally broad and topographically distributed activations. In contrast, comparisons between closely matched task conditions usually result in more focal differences. In the present study, we reanalyzed an existing set of MEG data recorded during stimulation with virtual Kanizsa figures and no-triangle control stimuli to contrast results yielded by the two approaches. Statistical analysis showed that visual stimulation compared to baseline gave rise to spectral amplitude reductions in lower frequencies including alpha and beta and amplitude enhancements in gamma frequencies above 55 Hz. These changes reached significance by about 100 ms post-stimulus onset, were topographically widespread over posterior cortex, and did not differ between stimuli. A second, more focal component over ventral occipital cortex peaked at about 300 ms in the gamma range at approximately 70 Hz. It was more pronounced for the Kanizsa triangle than for the no-triangle stimulus. A third gamma component over lateral occipito-temporal cortex showed an amplitude increase at around 450 ms for virtual figures and a concomitant decrease for the nongestalt-like control stimulus, and no overall task-related activity. Our findings illustrate that direct comparisons between conditions yield effects with a more focal spectral and topographical distribution than comparisons with a pre-stimulus baseline. Moreover, they exemplify that contrasts between conditions may reveal additional activations not captured by comparisons with a pre-stimulus baseline.
Collapse
Affiliation(s)
- Jochen Kaiser
- Institute of Medical Psychology, Johann Wolfgang Goethe University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt am Main, Germany.
| | | | | |
Collapse
|
433
|
Miller $^*$ KJ, Shenoy P, den Nijs M, Sorensen LB, Rao RPN, Ojemann JG. Beyond the Gamma Band: The Role of High-Frequency Features in Movement Classification. IEEE Trans Biomed Eng 2008; 55:1634-7. [DOI: 10.1109/tbme.2008.918569] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
434
|
Parieto-frontal gamma band activity during the perceptual emergence of speech forms. Neuroimage 2008; 42:404-13. [PMID: 18524627 DOI: 10.1016/j.neuroimage.2008.03.063] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 03/26/2008] [Accepted: 03/30/2008] [Indexed: 11/24/2022] Open
Abstract
The multistable perception of speech refers to the perceptual changes experienced while listening to a speech form cycled in rapid and continuous repetition, the so-called Verbal Transformation Effect. Because distinct interpretations of the same repeated stimulus alternate spontaneously, this effect provides an invaluable tool to examine how speech percepts are formed in the listener's mind. In order to track the temporal dynamics of brain activity specifically linked to perceptual changes, intracerebral EEG activity was recorded from two implanted epileptic patients while performing a verbal transformation task. To this aim, they were asked to carefully listen to a speech sequence played repeatedly and to press a button whenever they perceived a change in the repeated utterance. For both patients, 300-800 ms prior to the reported perceptual transitions, high frequency activity in the gamma band range (>40 Hz) was observed within the left inferior frontal and supramarginal gyri. An additional auditory decision task was used to rule out the possibility that the increased gamma band activity was due to the patients' motor responses. These results suggest that articulatory-based representations play a key part in the endogenously driven emergence of auditory speech percepts. The findings are interpreted in relation to theories assuming a link between perception and action in the human speech processing system.
Collapse
|
435
|
Alegre M, Alvarez-Gerriko I, Valencia M, Iriarte J, Artieda J. Oscillatory changes related to the forced termination of a movement. Clin Neurophysiol 2008; 119:290-300. [PMID: 18083620 DOI: 10.1016/j.clinph.2007.10.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 09/18/2007] [Accepted: 10/18/2007] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Stimulus-induced movements are accompanied by a definite pattern of oscillatory changes, that include a frontal 15 Hz synchronization, a central peri-movement desynchronization, and a contralateral beta rebound after the movement. Our aim was to study the oscillatory changes related to the forced termination of a single complex motor program (signature) and compare them with those observed after the normal termination of the movement. METHODS Fifty-eight reference-free EEG channels were analyzed in 10 healthy subjects. A 2000 Hz tone (S1, go signal) indicated the subject to begin to write his/her complete signature. A second 2000 Hz tone 0.8 s afterwards (50% probability: S2, stop signal) indicated the subject to stop immediately. Movement-related energy changes were evaluated by means of time-frequency (Gabor) transforms. RESULTS A frontal 15 Hz synchronization was observed after S1, but not after S2. The amplitude of the post-movement beta increase was significantly lower when the movement was abnormally terminated (p=0.005), while the peri-movement decrease was similar. CONCLUSIONS The forced termination of a motor program reduces significantly the amplitude of the post-movement beta increment, conserving its temporal pattern. Also, the presence of the 15 Hz frontal synchronization only after S1, together with the results of previous studies, suggests that the frontal mechanisms involved in go/no go and stop signals are very different. SIGNIFICANCE Our results indicate that the beta rebound is an active process, independent of the peri-movement beta decrease, which is influenced by how the movement is terminated.
Collapse
Affiliation(s)
- M Alegre
- Neurophysiology Laboratory, Neuroscience Area, CIMA, Universidad de Navarra, Pamplona, Spain
| | | | | | | | | |
Collapse
|
436
|
Brown EC, Rothermel R, Nishida M, Juhász C, Muzik O, Hoechstetter K, Sood S, Chugani HT, Asano E. In vivo animation of auditory-language-induced gamma-oscillations in children with intractable focal epilepsy. Neuroimage 2008; 41:1120-31. [PMID: 18455440 DOI: 10.1016/j.neuroimage.2008.03.011] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 03/09/2008] [Accepted: 03/13/2008] [Indexed: 10/22/2022] Open
Abstract
We determined if high-frequency gamma-oscillations (50- to 150-Hz) were induced by simple auditory communication over the language network areas in children with focal epilepsy. Four children (aged 7, 9, 10 and 16 years) with intractable left-hemispheric focal epilepsy underwent extraoperative electrocorticography (ECoG) as well as language mapping using neurostimulation and auditory-language-induced gamma-oscillations on ECoG. The audible communication was recorded concurrently and integrated with ECoG recording to allow for accurate time lock on ECoG analysis. In three children, who successfully completed the auditory-language task, high-frequency gamma-augmentation sequentially involved: i) the posterior superior temporal gyrus when listening to the question, ii) the posterior lateral temporal region and the posterior frontal region in the time interval between question completion and the patient's vocalization, and iii) the pre- and post-central gyri immediately preceding and during the patient's vocalization. The youngest child, with attention deficits, failed to cooperate during the auditory-language task, and high-frequency gamma-augmentation was noted only in the posterior superior temporal gyrus when audible questions were given. The size of language areas suggested by statistically significant high-frequency gamma-augmentation was larger than that defined by neurostimulation. The present method can provide in vivo imaging of electrophysiological activities over the language network areas during language processes. Further studies are warranted to determine whether recording of language-induced gamma-oscillations can supplement language mapping using neurostimulation in presurgical evaluation of children with focal epilepsy.
Collapse
Affiliation(s)
- Erik C Brown
- MD/PhD Program, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
437
|
Shenoy P, Miller KJ, Ojemann JG, Rao RPN. Generalized features for electrocorticographic BCIs. IEEE Trans Biomed Eng 2008; 55:273-80. [PMID: 18232371 DOI: 10.1109/tbme.2007.903528] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This paper studies classifiability of electrocorticographic signals (ECoG) for use in a human brain-computer interface (BCI). The results show that certain spectral features can be reliably used across several subjects to accurately classify different types of movements. Sparse and nonsparse versions of the support vector machine and regularized linear discriminant analysis linear classifiers are assessed and contrasted for the classification problem. In conjunction with a careful choice of features, the classification process automatically and consistently identifies neurophysiological areas known to be involved in the movements. An average two-class classification accuracy of 95% for real movement and around 80% for imagined movement is shown. The high accuracy and generalizability of these results, obtained with as few as 30 data samples per class, support the use of classification methods for ECoG-based BCIs.
Collapse
Affiliation(s)
- Pradeep Shenoy
- Department of Computer Science and Engineering, University of Washington, Seattle 98195, USA.
| | | | | | | |
Collapse
|
438
|
Abstract
Brain activity can be used as a control signal for brain-machine interfaces (BMIs). A powerful and widely acknowledged BMI approach, so far only applied in invasive recording techniques, uses neuronal signals related to limb movements for equivalent, multidimensional control of an external effector. Here, we investigated whether this approach is also applicable for noninvasive recording techniques. To this end, we recorded whole-head MEG during center-out movements with the hand and found significant power modulation of MEG activity between rest and movement in three frequency bands: an increase for < or = 7 Hz (low-frequency band) and 62-87 Hz (high-gamma band) and a decrease for 10-30 Hz (beta band) during movement. Movement directions could be inferred on a single-trial basis from the low-pass filtered MEG activity as well as from power modulations in the low-frequency band, but not from the beta and high-gamma bands. Using sensors above the motor area, we obtained a surprisingly high decoding accuracy of 67% on average across subjects. Decoding accuracy started to rise significantly above chance level before movement onset. Based on simultaneous MEG and EEG recordings, we show that the inference of movement direction works equally well for both recording techniques. In summary, our results show that neuronal activity associated with different movements of the same effector can be distinguished by means of noninvasive recordings and might, thus, be used to drive a noninvasive BMI.
Collapse
|
439
|
Quantification and visualisation of differences between two motor tasks based on energy density maps for brain–computer interface applications. Clin Neurophysiol 2008; 119:446-58. [DOI: 10.1016/j.clinph.2007.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Revised: 09/30/2007] [Accepted: 10/18/2007] [Indexed: 11/19/2022]
|
440
|
Schalk G, Miller KJ, Anderson NR, Wilson JA, Smyth MD, Ojemann JG, Moran DW, Wolpaw JR, Leuthardt EC. Two-dimensional movement control using electrocorticographic signals in humans. J Neural Eng 2008; 5:75-84. [PMID: 18310813 DOI: 10.1088/1741-2560/5/1/008] [Citation(s) in RCA: 287] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We show here that a brain-computer interface (BCI) using electrocorticographic activity (ECoG) and imagined or overt motor tasks enables humans to control a computer cursor in two dimensions. Over a brief training period of 12-36 min, each of five human subjects acquired substantial control of particular ECoG features recorded from several locations over the same hemisphere, and achieved average success rates of 53-73% in a two-dimensional four-target center-out task in which chance accuracy was 25%. Our results support the expectation that ECoG-based BCIs can combine high performance with technical and clinical practicality, and also indicate promising directions for further research.
Collapse
Affiliation(s)
- G Schalk
- BCI R&D Progr, Wadsworth Ctr, NYS Department of Health, Albany, NY, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
441
|
Lachaux JP, Fonlupt P, Kahane P, Minotti L, Hoffmann D, Bertrand O, Baciu M. Relationship between task-related gamma oscillations and BOLD signal: new insights from combined fMRI and intracranial EEG. Hum Brain Mapp 2008; 28:1368-75. [PMID: 17274021 PMCID: PMC6871347 DOI: 10.1002/hbm.20352] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Cognitive neuroscience relies on two sets of techniques to map the neural networks underlying cognition in humans: recordings of either regional metabolic changes (fMRI or PET) or fluctuations in the neural electromagnetic fields (EEG and MEG). Despite major advances in the last few years, an explicit linkage between the two is still missing and the neuroimaging community faces two complementary but unrelated sets of functional descriptions of the human brain. Such an explicit framework, linking the two approaches in potentially complex cognitive tasks and in a variety of brain regions would permit to combine them into fine spatio-temporally-grained human brain mapping procedures. We combined fMRI and intra-cranial EEG recordings of the same epileptic patients during a semantic decision task and found a close spatial correspondence between regions of fMRI activations and recording sites showing EEG energy modulations in the gamma range (>40 Hz). Our findings further support previous findings that gamma band modulations co-localize with BOLD variations and also indicate that fMRI may be used as a constraint to improve source reconstruction of gamma band EEG responses.
Collapse
|
442
|
Derakhshan I. Bimanual simultaneous movements and hemispheric dominance: Timing of events reveals hard-wired circuitry for action, speech, and imagination. Psychol Res Behav Manag 2008; 1:1-9. [PMID: 22110313 PMCID: PMC3218756 DOI: 10.2147/prbm.s4132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The evidence that speech is the marker of hemisphere of action is overwhelming. Thus, contrary to the commonly accepted belief, the evidence indicates that both sides of the body are under the same command (major hemisphere) and that the nondominant side of the body is a callosum-width farther from the major hemisphere. Substantial controversy exists, however, as to the best method for determining the laterality of motor control in an individual case. According to the new understanding, ie, the one-way callosal traffic circuitry underpinning laterality of motor control, the larger excursions of effectors located opposite (contralateral to) the command center while performing bimanual simultaneous drawing tasks provides the best noninvasive and inexpensive approach for demonstrating the laterality of the major hemisphere of a person (who is able to perform such tasks). Here, it is documented pictorially that bimanual simultaneous drawing of geometrical designs or straight lines, as well as moving the arms simultaneously from side to side (or up and down) while noting the difference of speed of the two arms (represented by the distance between the two index fingers), both provide a reliable indication of the laterality of a person’s major hemisphere. In all these maneuvers the nondominant side of the body (even the diaphragms) lags behind the dominant side by an interval equal to the interhemispheric transfer time (IHTT). This lagging behind of the nondominant side of the body in bimanual simultaneous movements is the footprint of directionality of callosal traffic underpinning the laterality of motor control evidenced by worsening of the delay of the nondominant side following callosotomy (uncoupling). Here, the historical precedence of a novel understanding in motor control together with its neurological implications in daily life as well as in laterality of seizure onset are briefly addressed, pointing out the deleterious effects of Sir Isaac Newton’s influence in neurological research on interhemispheric connectivity by suggesting symmetrical representation of visual sense of space in the human brain.
Collapse
Affiliation(s)
- Iraj Derakhshan
- Formerly of Department of Neurology, Case Western Reserve and Cincinnati Universities, Ohio, USA
| |
Collapse
|
443
|
Bai O, Lin P, Vorbach S, Floeter MK, Hattori N, Hallett M. A high performance sensorimotor beta rhythm-based brain–computer interface associated with human natural motor behavior. J Neural Eng 2007; 5:24-35. [PMID: 18310808 DOI: 10.1088/1741-2560/5/1/003] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
444
|
Lachaux JP, Jerbi K, Bertrand O, Minotti L, Hoffmann D, Schoendorff B, Kahane P. A blueprint for real-time functional mapping via human intracranial recordings. PLoS One 2007; 2:e1094. [PMID: 17971857 PMCID: PMC2040217 DOI: 10.1371/journal.pone.0001094] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 10/10/2007] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The surgical treatment of patients with intractable epilepsy is preceded by a pre-surgical evaluation period during which intracranial EEG recordings are performed to identify the epileptogenic network and provide a functional map of eloquent cerebral areas that need to be spared to minimize the risk of post-operative deficits. A growing body of research based on such invasive recordings indicates that cortical oscillations at various frequencies, especially in the gamma range (40 to 150 Hz), can provide efficient markers of task-related neural network activity. PRINCIPAL FINDINGS Here we introduce a novel real-time investigation framework for mapping human brain functions based on online visualization of the spectral power of the ongoing intracranial activity. The results obtained with the first two implanted epilepsy patients who used the proposed online system illustrate its feasibility and utility both for clinical applications, as a complementary tool to electrical stimulation for presurgical mapping purposes, and for basic research, as an exploratory tool used to detect correlations between behavior and oscillatory power modulations. Furthermore, our findings suggest a putative role for high gamma oscillations in higher-order auditory processing involved in speech and music perception. CONCLUSION/SIGNIFICANCE The proposed real-time setup is a promising tool for presurgical mapping, the investigation of functional brain dynamics, and possibly for neurofeedback training and brain computer interfaces.
Collapse
|
445
|
Wheaton LA, Carpenter M, Mizelle JC, Forrester L. Preparatory band specific premotor cortical activity differentiates upper and lower extremity movement. Exp Brain Res 2007; 184:121-6. [PMID: 17955226 DOI: 10.1007/s00221-007-1160-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Accepted: 09/26/2007] [Indexed: 11/28/2022]
Abstract
Event related desynchronization (ERD) allows evaluation of brain signals in multiple frequency dimensions. The purpose of this study was to determine left hemispheric non-primary motor cortex differences at varying frequencies of premovement ERD for similar movements by end-effectors of the upper and lower extremities. We recorded 32-channel electroencephalography (EEG) while subjects performed self-paced right ankle dorsiflexion and wrist extension. Electromyography (EMG) was recorded over the tibialis anterior and extensor carpi ulnaris. EEG was analyzed for premovement ERD within the alpha (8-12 Hz), low beta (13-18 Hz) and high beta (18-22 Hz) frequencies over the premotor, motor, and sensory areas of the left and mesial cortex from -1.5 to 0 s before movement. Within the alpha and high beta bands, wrist movements showed limited topography, but greater ERD over posterior premotor cortex areas. Alpha ERD was also significantly greater over the lateral motor cortex for wrist movements. In the low beta band, wrist movements provided extensive ERD differences to include the left motor and mesial/lateral premotor areas, whereas ankle movements showed only limited ERD activity. Overall, alpha and high beta activity demonstrated distinctions that are consistent with mapping of wrist and ankle representations over the sensorimotor strip, whereas the low beta representation demonstrated the clearest distinctions between the limbs over widespread brain areas, particularly the lateral premotor cortex. This suggests limited leg premovement activity at the dorsolateral premotor cortex. Low beta ERD may be reflect joint or limb specific preparatory activity in the premotor area. Further work is required to better evaluate the extent of this low beta activity for multiple comparative joints.
Collapse
Affiliation(s)
- Lewis A Wheaton
- Department of Veterans Affairs and the Baltimore VA Geriatric Research Education and Clinical Center (GRECC), Baltimore, MD 21201-1524, USA.
| | | | | | | |
Collapse
|
446
|
Canolty RT, Soltani M, Dalal SS, Edwards E, Dronkers NF, Nagarajan SS, Kirsch HE, Barbaro NM, Knight RT. Spatiotemporal dynamics of word processing in the human brain. Front Neurosci 2007; 1:185-96. [PMID: 18982128 PMCID: PMC2518055 DOI: 10.3389/neuro.01.1.1.014.2007] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Accepted: 09/01/2007] [Indexed: 11/13/2022] Open
Abstract
We examined the spatiotemporal dynamics of word processing by recording the electrocorticogram (ECoG) from the lateral frontotemporal cortex of neurosurgical patients chronically implanted with subdural electrode grids. Subjects engaged in a target detection task where proper names served as infrequent targets embedded in a stream of task-irrelevant verbs and nonwords. Verbs described actions related to the hand (e.g, throw) or mouth (e.g., blow), while unintelligible nonwords were sounds which matched the verbs in duration, intensity, temporal modulation, and power spectrum. Complex oscillatory dynamics were observed in the delta, theta, alpha, beta, low, and high gamma (HG) bands in response to presentation of all stimulus types. HG activity (80-200 Hz) in the ECoG tracked the spatiotemporal dynamics of word processing and identified a network of cortical structures involved in early word processing. HG was used to determine the relative onset, peak, and offset times of local cortical activation during word processing. Listening to verbs compared to nonwords sequentially activates first the posterior superior temporal gyrus (post-STG), then the middle superior temporal gyrus (mid-STG), followed by the superior temporal sulcus (STS). We also observed strong phase-locking between pairs of electrodes in the theta band, with weaker phase-locking occurring in the delta, alpha, and beta frequency ranges. These results provide details on the first few hundred milliseconds of the spatiotemporal evolution of cortical activity during word processing and provide evidence consistent with the hypothesis that an oscillatory hierarchy coordinates the flow of information between distinct cortical regions during goal-directed behavior.
Collapse
Affiliation(s)
- Ryan T Canolty
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-3190, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
447
|
Bocková M, Chládek J, Jurák P, Halámek J, Rektor I. Executive functions processed in the frontal and lateral temporal cortices: intracerebral study. Clin Neurophysiol 2007; 118:2625-36. [PMID: 17911041 DOI: 10.1016/j.clinph.2007.07.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 06/14/2007] [Accepted: 07/28/2007] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The study was designed to investigate the neurocognitive network in the frontal and lateral temporal cortices that is activated by the complex cognitive visuomotor tasks of letter writing. METHODS Eight epilepsy surgery candidates with implanted intracerebral depth electrodes performed two tasks involving the writing of single letters. The first task consisted of copying letters. In the second task, the patients were requested to write any other letter. The cognitive load of the second task was increased mainly by larger involvement of the executive functions. The task-related ERD/ERS of the alpha, beta and gamma rhythms was studied. RESULTS The alpha and beta ERD as the activational correlate of writing of single letters was found in the sensorimotor cortex, anterior cingulate, premotor, parietal cortices, SMA and the temporal pole. The alpha and beta ERD linked to the increased cognitive load was present moreover in the dorsolateral and ventrolateral prefrontal cortex, orbitofrontal cortex and surprisingly also the temporal neocortex. Gamma ERS was detected mostly in the left motor cortex. CONCLUSIONS Particularly the temporal neocortex was activated by the increased cognitive load. SIGNIFICANCE The lateral temporal cortex together with frontal areas forms a cognitive network processing executive functions.
Collapse
Affiliation(s)
- M Bocková
- First Department of Neurology, Masaryk University, St Anne's Hospital, 656 91, Brno, Czech Republic.
| | | | | | | | | |
Collapse
|
448
|
Erbil N, Ungan P. Changes in the alpha and beta amplitudes of the central EEG during the onset, continuation, and offset of long-duration repetitive hand movements. Brain Res 2007; 1169:44-56. [PMID: 17689502 DOI: 10.1016/j.brainres.2007.07.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2007] [Revised: 07/08/2007] [Accepted: 07/09/2007] [Indexed: 11/26/2022]
Abstract
Electroencephalographic alpha and beta activities recorded from central electrodes are known to display movement-related suppression or enhancement. We investigated whether the suppression that is known to occur during the onset of a single movement would persist or otherwise habituate when the movement is continuously repeated for a long period of time. Fourteen subjects took part in the experiments. They performed repetitive simultaneous extension-flexions of the fingers II-V in one hand, continuously for a period of at least 30 s. They then stopped this self-paced movement and rested for at least 30 s. Bipolar recording was made from C3-Cz and C4-Cz. Patterns of amplitude changes in the alpha and beta bands were calculated against a resting baseline. Following a bilateral alpha and beta suppression at the movement onset, alpha amplitude gradually but not fully recovered towards the baseline during the 30 s post-onset. Habituation of afferences and transfer of the cortical function were discussed as the two alternative explanations for this gradual recovery. Beta amplitude, however, displayed no recovery as long as the movement continued. Considering the relatively rapid beta recovery reported for sustained movements, this finding demonstrated that the sustained and continuous movements are conducted through quite different processes. A transient contralateral beta rebound was observed only after the end of the long movement period, strengthening the viewpoint that links the beta rebound with the closure of the cortical processes running throughout a motor sequence. Modulation of the beta amplitude, rather than the changes in alpha amplitude, appeared to be more closely correlated with the execution of a continuous movement.
Collapse
Affiliation(s)
- Nurhan Erbil
- Hacettepe University, Faculty of Medicine, Department of Biophysics, Ankara, Turkey
| | | |
Collapse
|
449
|
Lachaux JP, Jung J, Mainy N, Dreher JC, Bertrand O, Baciu M, Minotti L, Hoffmann D, Kahane P. Silence is golden: transient neural deactivation in the prefrontal cortex during attentive reading. Cereb Cortex 2007; 18:443-50. [PMID: 17617656 DOI: 10.1093/cercor/bhm085] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It is becoming increasingly clear that attention-demanding tasks engage not only activation of specific cortical regions but also deactivation of other regions that could interfere with the task at hand. At the same time, electrophysiological studies in animals and humans have found that the participation of cortical regions to cognitive processes translates into local synchronization of rhythmic neural activity at frequencies above 40 Hz (so-called gamma-band synchronization). Such synchronization is seen as a potential facilitator of neural communication and synaptic plasticity. We found evidence that cognitive processes can also involve the disruption of gamma-band activity in high-order brain regions. Intracerebral electroencephalograms were recorded in 3 epileptic patients during 2 reading tasks. Visual presentation of words induced a strong deactivation in a broad (20-150 Hz) frequency range in the left ventral lateral prefrontal cortex, in parallel with gamma-band activations within the reading network, including Broca's area. The observed energy decrease in neural signals was reproducible across patients. It peaked around 500 ms after stimulus onset and appeared subject to attention-modulated amplification. Our results suggest that cognition might be mediated by a coordinated interaction between regional gamma-band synchronizations and desynchronizations, possibly reflecting enhanced versus reduced local neural communication.
Collapse
|
450
|
Oishi N, Mima T, Ishii K, Bushara KO, Hiraoka T, Ueki Y, Fukuyama H, Hallett M. Neural correlates of regional EEG power change. Neuroimage 2007; 36:1301-12. [PMID: 17524671 DOI: 10.1016/j.neuroimage.2007.04.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 04/01/2007] [Accepted: 04/07/2007] [Indexed: 11/26/2022] Open
Abstract
To clarify the physiological significance of task-related change of the regional electroencephalogram (EEG) rhythm, we quantitatively evaluated the correlation between regional cerebral blood flow (rCBF) and EEG power. Eight subjects underwent H2 15O positron emission tomography scans simultaneously with EEG recording during the following tasks: rest condition with eyes closed and open, self-paced movements of the right and left thumb and right ankle. EEG signals were recorded from the occipital and bilateral sensorimotor areas. Cortical activation associated with EEG rhythm generation was studied by the correlation between rCBF and EEG power. There were significant negative correlations between the sensorimotor EEG rhythm at 10-20 Hz on each side and the ipsilateral sensorimotor rCBF and between the occipital EEG rhythm at 10-20 Hz and the occipital rCBF. The occipital EEG rhythm showed a positive correlation with the bilateral medial prefrontal rCBF, while the right sensorimotor EEG rhythm showed a positive correlation with the left prefrontal rCBF. In conclusion, decrease in the regional EEG rhythm at 10-20 Hz might represent the neuronal activation of the cortex underlying the electrodes, at least for the visual and sensorimotor areas. The neural network including the prefrontal cortex could play an important role to generate the EEG rhythm.
Collapse
Affiliation(s)
- N Oishi
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | | | | | | | | | | | | | | |
Collapse
|