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van Bijnen S, Parkkonen L, Parviainen T. Activity level in left auditory cortex predicts behavioral performance in inhibition tasks in children. Neuroimage 2022; 258:119371. [PMID: 35700945 DOI: 10.1016/j.neuroimage.2022.119371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 06/07/2022] [Accepted: 06/10/2022] [Indexed: 10/18/2022] Open
Abstract
Sensory processing during development is important for the emerging cognitive skills underlying goal-directed behavior. Yet, it is not known how auditory processing in children is related to their cognitive functions. Here, we utilized combined magneto- and electroencephalographic (M/EEG) measurements in school-aged children (6-14y) to show that child auditory cortical activity at ∼250 ms after auditory stimulation predicts the performance in inhibition tasks. While unaffected by task demands, the amplitude of the left-hemisphere activation pattern was significantly correlated with the variability of behavioral response time. Since this activation pattern is typically not present in adults, our results suggest divergent brain mechanisms in adults and children for consistent performance in auditory-based cognitive tasks. This difference can be explained as a shift in cortical resources for cognitive control from sensorimotor associations in the auditory cortex of children to top-down regulated control processes involving (pre)frontal and cingulate areas in adults.
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Affiliation(s)
- Sam van Bijnen
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland; Faculty of Science, University of Amsterdam, 1012 WX, Amsterdam, the Netherlands.
| | - Lauri Parkkonen
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
| | - Tiina Parviainen
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
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Kuderer S, Voracek M, Kirchengast S, Rotter CE. The Handedness Index Practical Task (HI 20): An economic behavioural measure for assessing manual preference. Laterality 2021; 27:273-307. [PMID: 34758712 DOI: 10.1080/1357650x.2021.1990312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
ABSTRACTBecause self-report hand preference measures are limited to investigating cognitive aspects of manual laterality, valid, easy-to-administer and economic behavioural methods are needed for capturing the motoric component of handedness. Therefore, this study introduces the Handedness Index Practical Task (HI20) and tests it in a sample of 206 students (Mage = 23.79 years, SDage = 3.01 years), half of whom were self-specified left-handers. After confirming good reliabilities at the subscale and total scale levels, k-means cluster analysis allowed an empirically based partitioning of test subjects into left- (n = 72), mixed- (n = 23) and right-handers (n = 111). To validate this categorization and the HI20 index, data were compared with the Edinburgh Handedness Inventory (EHI), EHI-short, HI22 and hand grip strength. The congruency between the HI20 clusters and alternative categorizations ranged from 95.6% to 84.0%, while the clusters explained large portions of variance in grip strength differences. The HI20 sub- and total scores showed strong correlations with other measures of lateral preference. Altogether, the freely available HI20 emerges as a reliable and valid alternative for behavioural handedness assessment, whose power lies in explaining differential hand use patterns and enabling fine-grained examinations of handedness.
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Affiliation(s)
- Sonja Kuderer
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
| | - Martin Voracek
- Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria
| | - Sylvia Kirchengast
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
| | - Christoph E Rotter
- Department of English and American Studies, University of Vienna, Vienna, Austria
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Wilenius J, Lehtinen H, Paetau R, Salmelin R, Kirveskari E. A simple magnetoencephalographic auditory paradigm may aid in confirming left-hemispheric language dominance in epilepsy patients. PLoS One 2018; 13:e0200073. [PMID: 29966017 PMCID: PMC6028140 DOI: 10.1371/journal.pone.0200073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 06/19/2018] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE The intracarotid amobarbital procedure (IAP) is the current "gold standard" in the preoperative assessment of language lateralization in epilepsy surgery candidates. It is, however, invasive and has several limitations. Here we tested a simple noninvasive language lateralization test performed with magnetoencephalography (MEG). METHODS We recorded auditory MEG responses to pairs of vowels and pure tones in 16 epilepsy surgery candidates who had undergone IAP. For each individual, we selected the pair of planar gradiometer sensors with the strongest N100m response to vowels in each hemisphere and-from the vector sum of signals of this gradiometer pair-calculated the vowel/tone amplitude ratio in the left (L) and right (R) hemisphere and, subsequently, the laterality index: LI = (L-R)/(L+R). In addition to the analysis using a single sensor pair, an alternative analysis was performed using averaged responses over 18 temporal sensor pairs in both hemispheres. RESULTS The laterality index did not correlate significantly with the lateralization data obtained from the IAP. However, an MEG pattern of stronger responses to vowels than tones in the left hemisphere and stronger responses to tones than vowels in the right hemisphere was associated with left-hemispheric language dominance in the IAP in all the six patients who showed this pattern. This results in a specificity of 100% and a sensitivity of 67% of this MEG pattern in predicting left-hemispheric language dominance (p = 0.01, Fisher's exact test). In the analysis using averaged responses over temporal channels, one additional patient who was left-dominant in IAP showed this particular MEG pattern, increasing the sensitivity to 78% (p = 0.003). SIGNIFICANCE This simple MEG paradigm shows promise in feasibly and noninvasively confirming left-hemispheric language dominance in epilepsy surgery candidates. It may aid in reducing the need for the IAP, if the results are confirmed in larger patient samples.
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Affiliation(s)
- Juha Wilenius
- Clinical Neurosciences, Department of Clinical Neurophysiology, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henri Lehtinen
- Epilepsy Unit, Department of Pediatric Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Ritva Paetau
- Clinical Neurosciences, Department of Clinical Neurophysiology, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Epilepsy Unit, Department of Pediatric Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Riitta Salmelin
- Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
| | - Erika Kirveskari
- Clinical Neurosciences, Department of Clinical Neurophysiology, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Nakamura I, Hirano Y, Ohara N, Hirano S, Ueno T, Tsuchimoto R, Kanba S, Onitsuka T. Early integration processing between faces and vowel sounds in human brain: an MEG investigation. Neuropsychobiology 2016; 71:187-95. [PMID: 26044647 DOI: 10.1159/000377680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 02/03/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Unconscious fast integration of face and voice information is a crucial brain function necessary for communicating effectively with others. Here, we investigated for evidence of rapid face-voice integration in the auditory cortex. METHODS Magnetic fields (P50m and N100m) evoked by visual stimuli (V), auditory stimuli (A) and audiovisual stimuli (VA), i.e. by face, vowel and simultaneous vowel-face stimuli, were recorded in 22 healthy subjects. Magnetoencephalographic data from 28 channels around bilateral auditory cortices were analyzed. RESULTS In both hemispheres, AV - V showed significantly larger P50m amplitudes than A. Additionally, compared with A, the N100m amplitudes and dipole moments of AV - V were significantly smaller in the left hemisphere, but not in the right hemisphere. CONCLUSIONS Differential changes in P50m (bilateral) and N100m (left hemisphere) that occur when V (faces) are associated with A (vowel sounds) indicate that AV (face-voice) integration occurs in early processing, likely enabling us to communicate effectively in our lives.
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Affiliation(s)
- Itta Nakamura
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Pirmoradi M, Jemel B, Gallagher A, Tremblay J, D’Hondt F, Nguyen DK, Béland R, Lassonde M. Verbal memory and verbal fluency tasks used for language localization and lateralization during magnetoencephalography. Epilepsy Res 2016; 119:1-9. [DOI: 10.1016/j.eplepsyres.2015.11.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/02/2015] [Accepted: 11/13/2015] [Indexed: 11/27/2022]
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Hardie SM, Wright L. Differences between left- and right-handers in approach/avoidance motivation: influence of consistency of handedness measures. Front Psychol 2014; 5:134. [PMID: 24600426 PMCID: PMC3929948 DOI: 10.3389/fpsyg.2014.00134] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 02/01/2014] [Indexed: 11/13/2022] Open
Abstract
Hand preference is often viewed as a troublesome variable in psychological research, with left-handers routinely excluded from studies. Contrary to this, a body of evidence has shown hand preference to be a useful variable when examining human behavior. A recent review argues that the most effective way of using handedness as a variable, is a comparison between individuals who use their dominant hand for virtually all manual activities (consistent handers) versus those who use their other hand for at least one activity (inconsistent handers). The authors contend that researchers should only focus on degree of handedness rather than direction of preference (left versus right). However, we argue that the field suffers from a number of methodological and empirical issues. These include a lack of consensus in choice of cut-off point to divide consistent and inconsistent categories and importantly a paucity of data from left-handers. Consequentially, researchers predominantly compare inconsistent versus consistent right-handers, largely linked to memory, cognition and language. Other research on response style and personality measures shows robust direction of handedness effects. The present study examines both strength and direction of handedness on self-reported behavioral inhibition system (BIS) and behavioral activation system (BAS) scores, using evidence from a large (N = 689) dataset including more than 200 left-handers. There were degree of handedness effects on BIS and BAS-Fun Seeking, but effects are largely driven by differences between consistent left-handers and other groups. Choice of cut-off point substantively influenced results, and suggests that unless a suitable sample of left-handers is included, researchers clarify that their degree of handedness effects are applicable only to right-handers. We concur that strength of hand preference is an important variable but caution that differences related to consistency may not be identical in right and left-handers.
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Affiliation(s)
- Scott M Hardie
- Evolutionary and Biological Approaches to Behaviour Research Group, School of Social and Health Sciences, University of Abertay Dundee, UK
| | - Lynn Wright
- Evolutionary and Biological Approaches to Behaviour Research Group, School of Social and Health Sciences, University of Abertay Dundee, UK
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Chu O, Abeare CA, Bondy MA. Inconsistent vs consistent right-handers' performance on an episodic memory task: evidence from the California Verbal Learning Test. Laterality 2011; 17:306-17. [PMID: 22594813 DOI: 10.1080/1357650x.2011.568490] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Inconsistent handedness is associated with better memory performance on episodic memory tasks than consistent handedness. The present study further explored this difference in memory related to handedness by administering a measure that is used in clinical settings to assess different aspects of long-term memory. The results indicated that inconsistent right-handed individuals recalled and recognised more words on the California Verbal Learning Test-II than consistent right-handed individuals. Inconsistent right-handers also showed better performance than consistent right-handers on measures of source recognition. The results of this study further extend the effects of handedness on memory to the clinical setting because the CVLT-II is a measure used extensively in clinical neuropsychology.
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Affiliation(s)
- Olivia Chu
- Department of Psychology, University of Windsor, Windsor, ON, Canada.
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The analysis of simple and complex auditory signals in human auditory cortex: magnetoencephalographic evidence from M100 modulation. Ear Hear 2010; 31:515-26. [PMID: 20445455 DOI: 10.1097/aud.0b013e3181d99a75] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Ecologically valid signals (e.g., vowels) have multiple components of substantially different frequencies and amplitudes that may not be equally cortically represented. In this study, we investigate a relatively simple signal at an intermediate level of complexity, two-frequency composite tones, a stimulus lying between simple sinusoids and ecologically valid signals such as speech. We aim to characterize the cortical response properties to better understand how complex signals may be represented in auditory cortex. DESIGN Using magnetoencephalography, we assessed the sensitivity of the M100/N100m auditory-evoked component to manipulations of the power ratio of the individual frequency components of the two-frequency complexes. Fourteen right-handed subjects with normal hearing were scanned while passively listening to 10 complex and 12 simple signals. The complex signals were composed of one higher frequency and one lower frequency sinusoid; the lower frequency sinusoidal component was at one of the five loudness levels relative to the higher frequency one: -20, -10, 0, +10, +20 dB. The simple signals comprised all the complex signal components presented in isolation. RESULTS The data replicate and extend several previous findings: (1) the systematic dependence of the M100 latency on signal intensity and (2) the dependence of the M100 latency on signal frequency, with lower frequency signals ( approximately 100 Hz) exhibiting longer latencies than higher frequency signals ( approximately 1000 Hz) even at matched loudness levels. (3) Importantly, we observe that, relative to simple signals, complex signals show increased response amplitude-as one might predict-but decreased M100 latencies. CONCLUSION : The data suggest that by the time the M100 is generated in auditory cortex ( approximately 70 to 80 msecs after stimulus onset), integrative processing across frequency channels has taken place which is observable in the M100 modulation. In light of these data models that attribute more time and processing resources to a complex stimulus merit reevaluation, in that our data show that acoustically more complex signals are associated with robust temporal facilitation, across frequencies and signal amplitude level.
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Kaploun KA, Abeare CA. Degree versus direction: A comparison of four handedness classification schemes through the investigation of lateralised semantic priming. Laterality 2010; 15:481-500. [DOI: 10.1080/13576500902958871] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Matilainen LE, Talvitie SS, Pekkonen E, Alku P, May PJC, Tiitinen H. The effects of healthy aging on auditory processing in humans as indexed by transient brain responses. Clin Neurophysiol 2010; 121:902-11. [PMID: 20359943 DOI: 10.1016/j.clinph.2010.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 12/18/2009] [Accepted: 01/08/2010] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The aim of the study was to investigate the effects of aging on human cortical auditory processing of rising-intensity sinusoids and speech sounds. We also aimed to evaluate the suitability of a recently discovered transient brain response for applied research. METHODS In young and aged adults, magnetic fields produced by cortical activity elicited by a 570-Hz pure-tone and a speech sound (Finnish vowel /a/) were measured using MEG. The stimuli rose smoothly in intensity from an inaudible to an audible level over 750 ms. We used both the active (attended) and the passive recording condition. In the attended condition, behavioral reaction times were measured. RESULTS The latency of the transient brain response was prolonged in the aged compared to the young and the accuracy of behavioral responses to sinusoids was diminished among the aged. In response amplitudes, no differences were found between the young and the aged. In both groups, spectral complexity of the stimuli enhanced response amplitudes. CONCLUSIONS Aging seems to affect the temporal dynamics of cortical auditory processing. The transient brain response is sensitive both to spectral complexity and aging-related changes in the timing of cortical activation. SIGNIFICANCE The transient brain responses elicited by rising-intensity sounds could be useful in revealing differences in auditory cortical processing in applied research.
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Affiliation(s)
- Laura E Matilainen
- Department of Biomedical Engineering and Computational Science, Aalto University, School of Science and Technology, Finland
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Howard MF, Poeppel D. Hemispheric asymmetry in mid and long latency neuromagnetic responses to single clicks. Hear Res 2009; 257:41-52. [PMID: 19647788 DOI: 10.1016/j.heares.2009.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 07/01/2009] [Accepted: 07/27/2009] [Indexed: 10/20/2022]
Abstract
We examine lateralization in the evoked magnetic field response to a click stimulus, observing that lateralization effects previously demonstrated for tones, noise, frequency modulated sweeps and certain syllables are also observed for (acoustically simpler) clicks. These effects include a difference in the peak latency of the M100 component of the evoked field waveform such that the peak consistently appears earlier in the right hemisphere, as well as rightward lateralization of field amplitude during the rise of the M100 component. Our review of previous findings on M100 lateralization, taken together with our data on the click-evoked response, leads to the hypothesis that these lateralization effects are elicited by stimuli containing a sharp sound energy onset or acoustic transition rather than specific types of stimuli. We argue that both the latency and the amplitude lateralization effects have a common origin, namely, hemispheric asymmetry in the amplitude of the magnetic field generated by one or more sources active during the M100 rise. While anatomical asymmetry cannot be excluded as the cause of the amplitude difference, we propose that the difference reflects a rightward asymmetry in the processing of sound energy onsets that potentially underlies the lateralization of several functions.
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Affiliation(s)
- Mary F Howard
- Department of Linguistics, University of Maryland, College Park, MD 20742-7505, USA.
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Kim JS, Chung CK. Language lateralization using MEG beta frequency desynchronization during auditory oddball stimulation with one-syllable words. Neuroimage 2008; 42:1499-507. [PMID: 18603004 DOI: 10.1016/j.neuroimage.2008.06.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 05/30/2008] [Accepted: 06/06/2008] [Indexed: 11/26/2022] Open
Abstract
Some patients with epilepsy have difficulty performing complex language tasks due to the long duration of the disease and cognitive side effects of antiepileptic drugs. Therefore, a simple passive paradigm would be useful for determining the language dominance lateralization in epilepsy patients. The goal of this study was to develop an efficient and non-invasive analysis method for determining language dominance in epilepsy patients. To this end, magnetoencephalography was performed while an auditory stimulus sequence comprised of two one-syllable spoken words was presented to 17 subjects in an oddball paradigm without subject response. The time-frequency difference between deviant and standard sounds was then analyzed in the source space using a spatial filtering method that was based on minimum-norm estimation. The laterality index was estimated in language-related regions of interest (ROI). The results were compared to the traditional lateralization method using the Wada test. Beta band oscillation activity decreased during deviant stimulation, and the lateralization of the decrease was in good agreement with the Wada test, in the posterior part of the inferior frontal gyrus in 94% of the subjects and in the posterior part of the superior temporal gyrus in 71% of the subjects. In conclusion, the ROI-based time-frequency difference between deviant and standard sounds can be used to assess language lateralization in accordance with the Wada test.
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Affiliation(s)
- June Sic Kim
- MEG Center, Department of Neurosurgery, Seoul National University College of Medicine, Republic of Korea
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Matilainen LE, Talvitie S, Alku P, Mäkelä A, Mäkinen V, May P, Pekkonen E, Tiitinen H. The cortical processing of rising-intensity tonal and speech stimuli in young adults: Effects of spectral complexity. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.ics.2007.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Salmelin R. Clinical neurophysiology of language: The MEG approach. Clin Neurophysiol 2007; 118:237-54. [PMID: 17008126 DOI: 10.1016/j.clinph.2006.07.316] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 06/01/2006] [Accepted: 07/28/2006] [Indexed: 01/12/2023]
Abstract
Clinical evaluation of language function and basic neuroscience research into the neurophysiology of language are tied together. Whole-head MEG systems readily facilitate detailed spatiotemporal characterization of language processes. A fair amount of information is available about the cortical sequence of word perception and comprehension in the auditory and visual domain, which can be applied for clinical use. Language production remains, at present, somewhat less well charted. In clinical practice, the most obvious needs are noninvasive evaluation of the language-dominant hemisphere and mapping of areas involved in language performance to assist surgery. Multiple experimental designs and analysis approaches have been proposed for estimation of language lateralization. Some of them have been compared with the invasive Wada test and need to be tested further. Development of approaches for more comprehensive pre-surgical characterization of language cortex should build on basic neuroscience research, making use of parametric designs that allow functional mapping. Studies of the neural basis of developmental and acquired language disorders, such as dyslexia, stuttering, and aphasia can currently be regarded more as clinical or basic neuroscience research rather than as clinical routine. Such investigations may eventually provide tools for development of individually targeted training procedures and their objective evaluation.
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Affiliation(s)
- Riitta Salmelin
- Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
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Mäkelä JP, Forss N, Jääskeläinen J, Kirveskari E, Korvenoja A, Paetau R. Magnetoencephalography in Neurosurgery. Neurosurgery 2006; 59:493-510; discussion 510-1. [PMID: 16955031 DOI: 10.1227/01.neu.0000232762.63508.11] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE:
To present applications of magnetoencephalography (MEG) in studies of neurosurgical patients.
METHODS:
MEG maps magnetic fields generated by electric currents in the brain, and allows the localization of brain areas producing evoked sensory responses and spontaneous electromagnetic activity. The identified sources can be integrated with other imaging modalities, e.g., with magnetic resonance imaging scans of individual patients with brain tumors or intractable epilepsy, or with other types of brain imaging data.
RESULTS:
MEG measurements using modern whole-scalp instruments assist in tailoring individual therapies for neurosurgical patients by producing maps of functionally irretrievable cortical areas and by identifying cortical sources of interictal and ictal epileptiform activity. The excellent time resolution of MEG enables tracking of complex spaciotemporal source patterns, helping, for example, with the separation of the epileptic pacemaker from propagated activity. The combination of noninvasive mapping of subcortical pathways by magnetic resonance imaging diffusion tensor imaging with MEG source localization will, in the near future, provide even more accurate navigational tools for preoperative planning. Other possible future applications of MEG include the noninvasive estimation of language lateralization and the follow-up of brain plasticity elicited by central or peripheral neural lesions or during the treatment of chronic pain.
CONCLUSION:
MEG is a mature technique suitable for producing preoperative “road maps” of eloquent cortical areas and for localizing epileptiform activity.
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Affiliation(s)
- Jyrki P Mäkelä
- BioMag Laboratory, Engineering Centre, Helsinki University Central Hospital, Helsinki, Finland.
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