A complementary analytic approach to examining medial temporal lobe sources using magnetoencephalography

Riggs, Lily; Moses, Sandra N.; Bardouille, Timothy; Herdman, Anthony T.; Roß, Bernhard; Ryan, Jennifer D.

doi:10.1016/j.neuroimage.2008.11.018

Cited by 64 publications

(66 citation statements)

References 97 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The SAM approach uses a linearly constrained minimum variance beamformer algorithm (Van Veen et al, 1997;Robinson and Vrba, 1999), normalizes source power across the whole cortical volume (Robinson, 2004), and is capable of revealing deep brain sources (Vrba and Robinson, 2001;Vrba, 2002). SAM source analysis has been successfully applied for identifying activities in auditory ) and sensorimotor cortices (Jurkiewicz et al, 2006), and deep sources such as hippocampus (Riggs et al, 2009) and fusiform gyrus and amygdala (Cornwell et al, 2008). In examining beta oscillation here, the beamformer was constructed specifically based on the covariances within the magnetic field data, for all epochs of 15-25 Hz bandpass filtered data from Ϫ200 to 1000 ms relative to stimulus onset.…”

Section: Methodsmentioning

confidence: 99%

Internalized Timing of Isochronous Sounds Is Represented in Neuromagnetic Beta Oscillations

Fujioka

Trainor²,

Large³

et al. 2012

J. Neurosci.

473

574

View full text Add to dashboard Cite

Moving in synchrony with an auditory rhythm requires predictive action based on neurodynamic representation of temporal information. Although it is known that a regular auditory rhythm can facilitate rhythmic movement, the neural mechanisms underlying this phenomenon remain poorly understood. In this experiment using human magnetoencephalography, 12 young healthy adults listened passively to an isochronous auditory rhythm without producing rhythmic movement. We hypothesized that the dynamics of neuromagnetic beta-band oscillations (ϳ20 Hz)-which are known to reflect changes in an active status of sensorimotor functions-would show modulations in both power and phase-coherence related to the rate of the auditory rhythm across both auditory and motor systems. Despite the absence of an intention to move, modulation of beta amplitude as well as changes in cortico-cortical coherence followed the tempo of sound stimulation in auditory cortices and motor-related areas including the sensorimotor cortex, inferior-frontal gyrus, supplementary motor area, and the cerebellum. The time course of beta decrease after stimulus onset was consistent regardless of the rate or regularity of the stimulus, but the time course of the following beta rebound depended on the stimulus rate only in the regular stimulus conditions such that the beta amplitude reached its maximum just before the occurrence of the next sound. Our results suggest that the time course of beta modulation provides a mechanism for maintaining predictive timing, that beta oscillations reflect functional coordination between auditory and motor systems, and that coherence in beta oscillations dynamically configure the sensorimotor networks for auditory-motor coupling.

show abstract

Section: Methodsmentioning

confidence: 99%

Internalized Timing of Isochronous Sounds Is Represented in Neuromagnetic Beta Oscillations

Fujioka

Trainor²,

Large³

et al. 2012

J. Neurosci.

473

574

View full text Add to dashboard Cite

show abstract

“…The output was the time courses of normalized source power for each volume element across the entire time interval. This approach, called event-related SAM (ER-SAM), proposed by Cheyne et al (2006), has been shown to be successful in reliably localizing evoked activities in motor cortex (Cheyne et al, 2006), auditory cortices (Ross et al, 2009a,b), or deeper source as hippocampus (Riggs et al, 2009) and fusiform face area and amygdala (Cornwell et al, 2008). Although previous studies, which were based on a different physiological assumption of changes in the power spectrum between an "active" poststimulus and the prestimulus "control" interval, suggested that the SAM image might be disadvantaged in localizing auditory evoked fields (Herdman et al, 2004), the ER-SAM approach used by Ross et al (2009a) has demonstrated that the time-averaged transient auditory evoked fields, in particular its long-latency components (80 -300 ms), are successfully localized in auditory areas on the superior temporal plane bilaterally and that different subareas reflect separate processing for onset and offset of tones.…”

Section: Methodsmentioning

confidence: 99%

Endogenous Neuromagnetic Activity for Mental Hierarchy of Timing

Fujioka¹,

Zendel²,

Roß³

2010

J. Neurosci.

View full text Add to dashboard Cite

The frontal-striatal circuits, the cerebellum, and motor cortices play crucial roles in processing timing information on second to millisecond scales. However, little is known about the physiological mechanism underlying human's preference to robustly encode a sequence of time intervals into a mental hierarchy of temporal units called meter. This is especially salient in music: temporal patterns are typically interpreted as integer multiples of a basic unit (i.e., the beat) and accommodated into a global context such as march or waltz. With magnetoencephalography and spatial-filtering source analysis, we demonstrated that the time courses of neural activities index a subjectively induced meter context. Auditory evoked responses from hippocampus, basal ganglia, and auditory and association cortices showed a significant contrast between march and waltz metric conditions during listening to identical click stimuli. Specifically, the right hippocampus was activated differentially at 80 ms to the march downbeat (the count one) and ϳ250 ms to the waltz downbeat. In contrast, basal ganglia showed a larger 80 ms peak for march downbeat than waltz. The metric contrast was also expressed in long-latency responses in the right temporal lobe. These findings suggest that anticipatory processes in the hippocampal memory system and temporal computation mechanism in the basal ganglia circuits facilitate endogenous activities in auditory and association cortices through feedback loops. The close interaction of auditory, motor, and limbic systems suggests a distributed network for metric organization in temporal processing and its relevance for musical behavior.

show abstract

“…A body of empirical evidence has accumulated demonstrating the ability of MEG to detect weak signals emanating from deep brain structures such as the hippocampi during a variety of tasks (Cornwell et al 2008a;Hamada et al 2004;Ioannides et al 1995;Kirsch et al 2003;Nishitani et al 1998), including memory tasks (Breier et al 1998;Breier et al 1999;Cornwell et al 2008a, b;Hanlon et al 2003;Hanlon et al 2005;Martin et al 2007; Moses et al 2009;Papanicolaou et al 2002;Riggs et al 2009;Tesche and Karhu 2000). Signals have also been detected from other deep neural structures such as the amygdalae (Cornwell et al 2007(Cornwell et al , 2008b(Cornwell et al , 2010Hung et al 2010;Ioannides et al 1995;Lui et al 1999;Luo et al 2007; Moses et al 2007;Streit et al 1999) and thalamus (Bardouille and Ross 2008;Bish et al 2004;Tesche 1996).…”

Section: Introductionmentioning

confidence: 99%

Techniques for Detection and Localization of Weak Hippocampal and Medial Frontal Sources Using Beamformers in MEG

et al. 2012

Self Cite

View full text Add to dashboard Cite

Magnetoencephalography provides precise information about the temporal dynamics of brain activation and is an ideal tool for investigating rapid cognitive processing. However, in many cognitive paradigms visual stimuli are used, which evoke strong brain responses (typically 40-100 nAm in V1) that may impede the detection of weaker activations of interest. This is particularly a concern when beamformer algorithms are used for source analysis, due to artefacts such as "leakage" of activation from the primary visual sources into other regions. We have previously shown (Quraan et al. 2011) that we can effectively reduce leakage patterns and detect weak hippocampal sources by subtracting the functional images derived from the experimental task and a control task with similar stimulus parameters. In this study we assess the performance of three different subtraction techniques. In the first technique we follow the same post-localization subtraction procedures as in our previous work. In the second and third techniques, we subtract the sensor data obtained from the experimental and control paradigms prior to source localization. Using simulated signals embedded in real data, we show that when beamformers are used, subtraction prior to source localization allows for the detection of weaker sources and higher localization accuracy. The improvement in localization accuracy exceeded 10 mm at low signal-to-noise ratios, and sources down to below 5 nAm were detected. We applied our techniques to empirical data acquired with two different paradigms designed to evoke hippocampal and frontal activations, and demonstrated our ability to detect robust activations in both regions with substantial improvements over image subtraction. We conclude that removal of the common-mode dominant sources through data subtraction prior to localization further improves the beamformer's ability to project the n-channel sensor-space data to reveal weak sources of interest and allows more accurate localization.

show abstract

A complementary analytic approach to examining medial temporal lobe sources using magnetoencephalography

Cited by 64 publications

References 97 publications

Internalized Timing of Isochronous Sounds Is Represented in Neuromagnetic Beta Oscillations

Internalized Timing of Isochronous Sounds Is Represented in Neuromagnetic Beta Oscillations

Endogenous Neuromagnetic Activity for Mental Hierarchy of Timing

Techniques for Detection and Localization of Weak Hippocampal and Medial Frontal Sources Using Beamformers in MEG

Contact Info

Product

Resources

About