Impact of orbitofrontal lesions on electrophysiological signals in a stop signal task

Authors:

• Anne-Kristin Solbakk

• Ingrid Funderud

• Tor Endestad

• Torstein Meling

• Magnus Lindgren

• Robert T. Knight

• Ulrike M. Krämer

Date: 2014

DOI: 10.1162/jocn_a_00561

PubMed: 24392904

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Abstract:

Behavioral inhibition and performance monitoring are critical cognitive functions supported by distributed neural networks including the pFC. We examined neurophysiological correlates of motor response inhibition and action monitoring in patients with focal orbitofrontal (OFC) lesions (n = 12) after resection of a primary intracranial tumor or contusion because of traumatic brain injury. Healthy participants served as controls (n = 14). Participants performed a visual stop signal task. We analyzed behavioral performance as well as event-related brain potentials and oscillations. Inhibition difficulty was adjusted individually to yield an equal amount of successful inhibitions across participants. RTs of patients and controls did not differ significantly in go trials or in failed stop trials, and no differences were observed in estimated stop signal RT. However, electrophysiological response patterns during task performance distinguished the groups. Patients with OFC lesions had enhanced P3 amplitudes to congruent condition go signals and to stop signals. In stop trials, patients had attenuated N2 and error-related negativity, but enhanced error positivity. Patients also showed enhanced and prolonged post-error beta band increases for stop errors. This effect was particularly evident in patients whose lesion extended to the subgenual cingulate cortex. In summary, although response inhibition was not impaired, the diminished stop N2 and ERN support a critical role of the OFC in action monitoring. Moreover, the increased stop P3, error positivity, and post-error beta response indicate that OFC injury affected action outcome evaluation and support the notion that the OFC is relevant for the processing of abstract reinforcers such as performing correctly in the task.

Impaired facilitatory mechanisms of auditory selective attention after damage of the lateral prefrontal cortex

Authors:

• Aurélie Bidet-Caulet

• K. Buchanan

• H. Viswanath

• Jessica Black

• Frederique Bonnet-Brilhault

• Robert T. Knight

Date: 2014

DOI: 10.1093/cercor/bhu131

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Abstract:

There is growing evidence that auditory selective attention operates via distinct facilitatory and inhibitory mechanisms enabling selective enhancement and suppression of sound processing, respectively. The lateral prefrontal cortex (LPFC) plays a crucial role in the top-down control of selective attention. However, whether the LPFC controls facilitatory, inhibitory, or both attentional mechanisms is unclear. Facilitatory and inhibitory mechanisms were assessed, in patients with LPFC damage, by comparing event-related potentials (ERPs) to attended and ignored sounds with ERPs to these same sounds when attention was equally distributed to all sounds. In control subjects, we observed 2 late frontally distributed ERP components: a transient facilitatory component occurring from 150 to 250 ms after sound onset; and an inhibitory component onsetting at 250 ms. Only the facilitatory component was affected in patients with LPFC damage: this component was absent when attending to sounds delivered in the ear contralateral to the lesion, with the most prominent decreases observed over the damaged brain regions. These findings have 2 important implications: (i) they provide evidence for functionally distinct facilitatory and inhibitory mechanisms supporting late auditory selective attention; (ii) they show that the LPFC is involved in the control of the facilitatory mechanisms of auditory attention.

Low attentional engagement makes attention network activity susceptible to emotional interference

Authors:

• Robert T. Knight

• Kaisa M. Hartikainen

• Keith H. Ogawa

• Natasha Pickard

• Anne-Kristin Solbakk

• Verónica Mäki-Marttu

Date: 2014

DOI: 10.1097/WNR.0000000000000223

PubMed: 4162342

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Abstract:

The aim of this study was to investigate whether emotion–attention interaction depends on attentional engagement. To investigate emotional modulation of attention network activation, we used a functional MRI paradigm consisting of a visuospatial attention task with either frequent (high-engagement) or infrequent (low-engagement) targets and intermittent emotional or neutral distractors. The attention task recruited a bilateral frontoparietal network with no emotional interference on network activation when the attentional engagement was high. In contrast, when the attentional engagement was low, the unpleasant stimuli interfered with the activation of the frontoparietal attention network, especially in the right hemisphere. This study provides novel evidence for low attentional engagement making attention control network activation susceptible to emotional interference.

Decoding Speech for Understanding and Treating Aphasia

Authors:

• Brian Pasley

• Robert T. Knight

Date: 2015

DOI: 10.1016/B978-0-444-63327-9.00018-7

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Abstract:

Aphasia is an acquired language disorder with a diverse set of symptoms that can affect virtually any linguistic modality across both the comprehension and production of spoken language. Partial recovery of language function after injury is common but typically incomplete. Rehabilitation strategies focus on behavioral training to induce plasticity in underlying neural circuits to maximize linguistic recovery. Understanding the different neural circuits underlying diverse language functions is a key to developing more effective treatment strategies. This chapter discusses a systems identification analytic approach to the study of linguistic neural representation. The focus of this framework is a quantitative, model-based characterization of speech and language neural representations that can be used to decode, or predict, speech representations from measured brain activity. Recent results of this approach are discussed in the context of applications to understanding the neural basis of aphasia symptoms and the potential to optimize plasticity during the rehabilitation process.

Decoding spectrotemporal features of overt and covert speech from the human cortex

Authors:

• Stéphanie Martin

• Peter Brunner

• Chris Holdgraf

• Hans-Jochen Heinze

• Nathan E. Crone

• Jochem W. Rieger

• Gerwin Schalk

• Robert T. Knight

• Brian Pasley

Date: 2014

DOI: 10.3389/fneng.2014.00014

PubMed: 4034498

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Abstract:

Auditory perception and auditory imagery have been shown to activate overlapping brain regions. We hypothesized that these phenomena also share a common underlying neural representation. To assess this, we used electrocorticography intracranial recordings from epileptic patients performing an out loud or a silent reading task. In these tasks, short stories scrolled across a video screen in two conditions: subjects read the same stories both aloud (overt) and silently (covert). In a control condition the subject remained in a resting state. We first built a high gamma (70–150 Hz) neural decoding model to reconstruct spectrotemporal auditory features of self-generated overt speech. We then evaluated whether this same model could reconstruct auditory speech features in the covert speech condition. Two speech models were tested: a spectrogram and a modulation-based feature space. For the overt condition, reconstruction accuracy was evaluated as the correlation between original and predicted speech features, and was significant in each subject (p < 10−5; paired two-sample t-test). For the covert speech condition, dynamic time warping was first used to realign the covert speech reconstruction with the corresponding original speech from the overt condition. Reconstruction accuracy was then evaluated as the correlation between original and reconstructed speech features. Covert reconstruction accuracy was compared to the accuracy obtained from reconstructions in the baseline control condition. Reconstruction accuracy for the covert condition was significantly better than for the control condition (p < 0.005; paired two-sample t-test). The superior temporal gyrus, pre- and post-central gyrus provided the highest reconstruction information. The relationship between overt and covert speech reconstruction depended on anatomy. These results provide evidence that auditory representations of covert speech can be reconstructed from models that are built from an overt speech data set, supporting a partially shared neural substrate.

Spatial and temporal relationships of electrocorticographic alpha and gamma activity during auditory processing

Authors:

• Cristhian Potes

• Peter Brunner

• Ayesegul Gunduz

• Robert T. Knight

• Gerwin Schalk

Date: 2014

DOI: Neuroimaging approaches have implicated multiple b

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Abstract:

Neuroimaging approaches have implicated multiple brain sites in musical perception, including the posterior part of the superior temporal gyrus and adjacent perisylvian areas. However, the detailed spatial and temporal relationship of neural signals that support auditory processing is largely unknown. In this study, we applied a novel inter-subject analysis approach to electrophysiological signals recorded from the surface of the brain (electrocorticography (ECoG)) in ten human subjects. This approach allowed us to reliably identify those ECoG features that were related to the processing of a complex auditory stimulus (i.e., continuous piece of music) and to investigate their spatial, temporal, and causal relationships. Our results identified stimulus-related modulations in the alpha (8–12 Hz) and high gamma (70–110 Hz) bands at neuroanatomical locations implicated in auditory processing. Specifically, we identified stimulus-related ECoG modulations in the alpha band in areas adjacent to primary auditory cortex, which are known to receive afferent auditory projections from the thalamus (80 of a total of 15,107 tested sites). In contrast, we identified stimulus-related ECoG modulations in the high gamma band not only in areas close to primary auditory cortex but also in other perisylvian areas known to be involved in higher-order auditory processing, and in superior premotor cortex (412/15,107 sites). Across all implicated areas, modulations in the high gamma band preceded those in the alpha band by 280 ms, and activity in the high gamma band causally predicted alpha activity, but not vice versa (Granger causality, p < 1e− 8). Additionally, detailed analyses using Granger causality identified causal relationships of high gamma activity between distinct locations in early auditory pathways within superior temporal gyrus (STG) and posterior STG, between posterior STG and inferior frontal cortex, and between STG and premotor cortex. Evidence suggests that these relationships reflect direct cortico-cortical connections rather than common driving input from subcortical structures such as the thalamus. In summary, our inter-subject analyses defined the spatial and temporal relationships between music-related brain activity in the alpha and high gamma bands. They provide experimental evidence supporting current theories about the putative mechanisms of alpha and gamma activity, i.e., reflections of thalamo-cortical interactions and local cortical neural activity, respectively, and the results are also in agreement with existing functional models of auditory processing.

Oscillatory dynamics track motor learning in human cortex

Authors:

• S. Durschmid

• Fanny Quandt

• Ulrike M. Krämer

• Hermann Hinrichs

• R. T. Schultz

• H. Pannek

• Edward F. Chang

• Robert T. Knight

Date: 2014

DOI: 10.1371/journal.pone.0089576

PubMed: 24586885

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Abstract:

Improving performance in motor skill acquisition is proposed to be supported by tuning of neural networks. To address this issue we investigated changes of phase-amplitude cross-frequency coupling (paCFC) in neuronal networks during motor performance improvement. We recorded intracranially from subdural electrodes (electrocorticogram; ECoG) from 6 patients who learned 3 distinct motor tasks requiring coordination of finger movements with an external cue (serial response task, auditory motor coordination task, go/no-go). Performance improved in all subjects and all tasks during the first block and plateaued in subsequent blocks. Performance improvement was paralleled by increasing neural changes in the trial-to-trial paCFC between theta ([Formula: see text]; 4-8 Hz) phase and high gamma (HG; 80-180 Hz) amplitude. Electrodes showing this covariation pattern (Pearson's r ranging up to .45) were located contralateral to the limb performing the task and were observed predominantly in motor brain regions. We observed stable paCFC when task performance asymptoted. Our results indicate that motor performance improvement is accompanied by adjustments in the dynamics and topology of neuronal network interactions in the [Formula: see text] and HG range. The location of the involved electrodes suggests that oscillatory dynamics in motor cortices support performance improvement with practice.

Hypertension drives parenchymal b -amyloid accumulationin the brain parenchyma

Authors:

• Robert T. Knight

• Hans-Jochen Heinze

• Celine Bueche

• Cheryl Hawkes

• Cornelia Garz

• Stefan Vielhaber

• Johannes Attems

• Klaus Reymann

• Roxana Carare

• Stefanie Schreiber

Date: 2014

DOI: 10.1002/acn3.27

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Abstract:

There is substantial controversy regarding the causative role of amyloid b (Ab)deposition in Alzheimer’s disease (AD). The cerebrovasculature plays an impor-tant role in the elimination of Ab from the brain and hypertension is a well-known risk factor for AD. In spontaneously hypertensive stroke-prone rats(SHRSP), an animal model of chronic arterial hypertension, cerebral small ves-sel disease (CSVD) leads to age-dependent parenchymal Ab accumulation simi-lar to that observed in AD. These data approve the neuropathological linkbetween CSVD and AD, confirm the challenge that parenchymal Ab depositionis a specific marker for AD and disclose the meaning of SHRSP as valid experi-mental model to investigate the association between hypertension, CSVD, and Ab plaques.

Network dynamics predict improvement in working memory performance following Donezepil administration in health young controls

Authors:

• Amit Reches

• Ilan Laufer

• Guy Cukierman

• Kevin McEvoy

• M. Ettinger

Date: 2013

DOI: 10.1016/j.neuroimage.2013.11.020

PubMed: 24269569

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Abstract:

Attentional selection in the context of goal-directed behavior involves top-down modulation to enhance the contrast between relevant and irrelevant stimuli via enhancement and suppression of sensory cortical activity. Acetylcholine (ACh) is believed to be involved mechanistically in such attention processes. The objective of the current study was to examine the effects of donepezil, a cholinesterase inhibitor that increases synaptic levels of ACh, on the relationship between performance and network dynamics during a visual working memory (WM) task involving relevant and irrelevant stimuli. Electroencephalogram (EEG) activity was recorded in 14 healthy young adults while they performed a selective face/scene working memory task. Each participant received either placebo or donepezil (5mg, orally) on two different visits in a double-blinded study. To investigate the effects of donepezil on brain network dynamics we utilized a novel EEG-based Brain Network Activation (BNA) analysis method that isolates location-time-frequency interrelations among event-related potential (ERP) peaks and extracts condition-specific networks. The activation level of the network modulated by donepezil, reflected in terms of the degree of its dynamical organization, was positively correlated with WM performance. Further analyses revealed that the frontal-posterior theta-alpha sub-network comprised the critical regions whose activation level correlated with beneficial effects on cognitive performance. These results indicate that condition-specific EEG network analysis could potentially serve to predict beneficial effects of therapeutic treatment in working memory.

Role of the lateral prefrontal cortex in speech monitoring

Authors:

• Stephanie Ries

• Kira Xie

• Kathleen Y. Haaland

• Nina F. Dronkers

• Robert T. Knight

Date: 2013

DOI: 10.3389/fnhum.2013.00703

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Abstract:

The role of lateral prefrontal cortex (LPFC) in speech monitoring has not been delineated. Recent work suggests that medial frontal cortex (MFC) is involved in overt speech monitoring initiated before auditory feedback. This mechanism is reflected in an event- related potential (ERP), the error negativity (Ne), peaking within 100 ms after vocal-onset. Critically, in healthy individuals the Ne is sensitive to the accuracy of the response; it is larger for error than correct trials. By contrast, patients with LPFC damage are impaired in non-verbal monitoring tasks showing no amplitude difference between the Ne measured in correct vs. error trials. Interactions between the LPFC and the MFC are assumed to play a necessary role for normal action monitoring. We investigated whether the LPFC was involved in speech monitoring to the same extent as in non-linguistic actions by comparing performance and EEG activity in patients with LPFC damage and in aged-matched controls performing linguistic (Picture Naming) and non-linguistic (Simon) tasks. Controls did not produce enough errors to allow the comparison of the Ne or other ERP in error vs. correct trials. PFC patients had worse performance than controls in both tasks, but their Ne was larger for error than correct trials only in Naming. This task-dependent pattern can be explained by LPFC-dependent working-memory requirements present in non-linguistic tasks used to study action monitoring but absent in picture naming. This suggests that LPFC may not be necessary for speech monitoring as assessed by simple picture naming. In addition, bilateral temporal cortex activity starting before and peaking around vocal-onset was observed in LPFC and control groups in both tasks but was larger for error than correct trials only in Naming, suggesting the temporal cortex is associated with on-line monitoring of speech specifically when access to lexical representations is necessary.

Phase-amplitude cross-frequency coupling in the human nucleus acumbens tracks action monitoring during cognitive control

Authors:

• S. Durschmid

• Tino Zaehle

• Klaus Kopitzki

• Jürgen Voges

• Friedhelm Schmitt

• Hans-Jochen Heinze

• Robert T. Knight

• Hermann Hinrichs

Date: 2013

DOI: 10.3389/fnhum.2013.00635

PubMed: 24586885

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Abstract:

The Nucleus Accumbens (NAcc) is an important structure for the transfer of information between cortical and subcortical structures, especially the prefrontal cortex and the hippocampus. However, the mechanism that allows the NAcc to achieve this integration is not well understood. Phase-amplitude cross-frequency coupling (PAC) of oscillations in different frequency bands has been proposed as an effective mechanism to form functional networks to optimize transfer and integration of information. Here we assess PAC between theta and high gamma oscillations as a potential mechanism that facilitates motor adaptation. To address this issue we recorded intracranial field potentials directly from the bilateral human NAcc in three patients while they performed a motor learning task that varied in the level of cognitive control needed to perform the task. As in rodents, PAC was observable in the human NAcc, transiently occurring contralateral to a movement following the motor response. Importantly, PAC correlated with the level of cognitive control needed to monitor the action performed. This functional relation indicates that the NAcc is engaged in action monitoring and supports the evaluation of motor programs during adaptive behavior by means of PAC.

Error-monitoring and post-error compensations: dissociation between perceptual failures and motor errors with and without awareness

Authors:

• Robert T. Knight

• Ana Navarro-Cebrian

• Andrew S. Kayser

Date: 2013

DOI: 10.1523/JNEUROSCI.0447-13.2013

PubMed: 23884943

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Abstract:

Whether humans adjust their behavior in response to unaware errors remains a controversial issue relevant to insight in neuropsychiatric conditions. Initial error awareness studies found that the error-related negativity (ERN), an event-related potential (ERP) originating in the medial prefrontal cortex after errors, activated equally for aware and unaware errors, suggesting a candidate preconscious mechanism. However, recent studies demonstrate that the ERN decreases after unaware errors. We hypothesized that the ERN is dependent upon awareness, and predicted that previous discrepancies might be due to unaware errors not being differentiated from perceptually uncertain, low-confidence responses that might increase the ERN amplitude. Here we addressed this hypothesis by distinguishing between aware errors, unaware errors, and uncertain responses, and using stimuli (faces) associated with well established sensory ERPs to evaluate the degree of stimulus processing for each trial type. We found that while aware and unaware errors were related to failures at the time of response, uncertain responses were due to failures at the time of stimulus processing indexed by lower amplitude sensory ERPs. Moreover, uncertain responses showed similar ERN activity as aware errors, in comparison with decreased activity for unaware errors. Finally, compared with aware errors, uncertain responses and unaware errors showed reduced neural compensations, such as alpha suppression. Together these findings suggest that the ERN is activated by aware motor errors as well as sensory failures, and that both awareness and certainty are necessary for neural adaptations after errors.

Preparatory attention after lesions to the lateral or orbital prefrontal cortex: an event-related potential study

Authors:

• Ingrid Funderud

• Marianne Lovstad

• Magnus Lindgren

• Tor Endestad

• Paulina Due-Tønnesse

• Torstein Meling

• Robert T. Knight

• Anne-Kristin Solbakk

Date: 2013

PubMed: 23831520

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Abstract:

The prefrontal cortex (PFC) plays a central role in preparatory and anticipatory attentional processes. To investigate whether subregions of the PFC play differential roles in these processes we investigated the effect of focal lesions to either lateral prefrontal (lateral PFC; n=11) or orbitofrontal cortex (OFC; n=13) on the contingent negative variation (CNV), an electrophysiological index of preparatory brain processes. The CNV was studied using a Go/NoGo delayed response task where an auditory S1 signaled whether or not an upcoming visual S2 was a Go or a NoGo stimulus. Neither early (500–1000 ms) nor late (3200–3700 ms) phase Go trial CNV amplitude was reduced for any of the patient groups in comparison to controls. However, the lateral PFC group showed enhanced Go trial early CNV and reduced late CNV Go/NoGo differentiation. These data suggests that normal orienting and evaluation as reflected by the CNV is intact after OFC lesions. The enhanced early CNV after lateral PFC damage may be due to failure in inhibition and the reduced late CNV difference wave confirms a deficit in preparatory attention after damage to this frontal subregion.

Independence of valence and reward in emotional word processing: Electrophysiological evidence

Authors:

• Laura Kaltwasser

• Stephanie Ries

• Werner Sommer

• Robert T. Knight

• Roel M. Willems

Date: 2013

DOI: 10.3389/fpsyg.2013.00168

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Abstract:

Both emotion and reward are primary modulators of cognition: Emotional word content enhances word processing, and reward expectancy similarly amplifies cognitive processing from the perceptual up to the executive control level. Here, we investigate how these primary regulators of cognition interact. We studied how the anticipation of gain or loss modulates the neural time course (event-related potentials, ERPs) related to processing of emotional words. Participants performed a semantic categorization task on emotional and neutral words, which were preceded by a cue indicating that performance could lead to monetary gain or loss. Emotion-related and reward-related effects occurred in different time windows, did not interact statistically, and showed different topographies. This speaks for an independence of reward expectancy and the processing of emotional word content. Therefore, privileged processing given to emotionally valenced words seems immune to short-term modulation of reward. Models of language comprehension should be able to incorporate effects of reward and emotion on language processing, and the current study argues for an architecture in which reward and emotion do not share a common neurobiological mechanism.

Multiplexed memories: a view from human cortex

Authors:

• Robert T. Knight

• Howard Eichenbaum

Date: 2013

DOI: 10.1038/nn.3341

PubMed: 23434977

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Abstract:

A study recording directly from the human brain shows that connectivity between the prefrontal cortex, parietal cortex and the medial temporal lobe across different frequency bands underlies successful memory retrieval.

Age-related frontal-parietal changes during the control of bottom-up and top-down attention: an ERP study

Authors:

• Ling Li

• Caterina Gratton

• Monica Fabiani

• Robert T. Knight

Date: 2013

DOI: 10.1016

PubMed: 22459599

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Abstract:

We investigated age-related changes in frontal and parietal scalp event-related potential (ERP) activity during bottom-up and top-down attention. Younger and older participants were presented with arrays constructed to induce either automatic "pop-out" (bottom-up) or effortful "search" (top-down) behavior. Reaction times (RTs) increased and accuracy decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. The latency of the P300 elicited by the visual search array was shorter in both conditions in the younger than in the older adults. Pop-out target detection was associated with greater activity at parietal than at prefrontal locations in younger participants and with a more equipotential prefrontal-parietal distribution in older adults. Search target detection was associated with greater activity at prefrontal than at parietal locations in older relative to younger participants. Thus, aging was associated with a more prefrontal P300 scalp distribution during the control of bottom-up and top-down attention. Early latency extrastriate potentials were enhanced and N2-posterior-contralateral (N2pc) was reduced in the older group, supporting the idea that the frontal enhancements may be due to a compensation for disinhibition and distraction in the older adults. Taken together these findings provide evidence that younger and older adults recruit different frontal-parietal networks during top-down and bottom-up attention, with older adults increasing their recruitment of a more frontally distributed network in both of these types of attention. This work is in accord with previous neuroimaging findings suggesting that older adults recruit more frontal activity in the service of a variety of tasks than younger adults.

Oscillations and behavior: the role of phase-amplitude coupling in cognition

Authors:

• Boaz Sadeh

• Sara Szczepanski

• Robert T. Knight

Date: 2013

Proceedings of the Third International Workshop on Advances in Electrocorticography

Authors:

• Anthony Ritaccio

• Michael Beauchamp

• Conrado Bosman

• Peter Brunner

• Edward F. Chang

• Nathan E. Crone

• Ayesegul Gunduz

• Disha Gupta

• Robert T. Knight

• Eric Leuthardt

• Brian Litt

• Daniel Moran

• Jeffrey G. Ojemann

• Josef Parvizi

• Nick F. Ramsey

• Jochem W. Rieger

• Jonathan Viventi

• Bradley Voytek

• Justin Williams

• Gerwin Schalk

Date: 2012

DOI: 10.1016/j.yebeh.2012.09.016

PubMed: 23160096

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Abstract:

The Third International Workshop on Advances in Electrocorticography (ECoG) was convened in Washington, DC, on November 10–11, 2011. As in prior meetings, a true multidisciplinary fusion of clinicians, scientists, and engineers from many disciplines gathered to summarize contemporary experiences in brain surface recordings. The proceedings of this meeting serve as evidence of a very robust and transformative field but will yet again require revision to incorporate the advances that the following year will surely bring.

Differential Go/NoGo activity in both contingent negative variation and spectral power

Authors:

• Ingrid Funderud

• Magnus Lindgren

• Marianne Lovstad

• Tor Endestad

• Bradley Voytek

• Robert T. Knight

• Anne-Kristin Solbakk

Date: 2012

DOI: 10.1371/journal.pone.0048504

PubMed: 23119040

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Abstract:

We investigated whether both the contingent negative variation (CNV), an event-related potential index of preparatory brain activity, and event-related oscillatory EEG activity differentiated Go and NoGo trials in a delayed response task. CNV and spectral power (4-100 Hz) were calculated from EEG activity in the preparatory interval in 16 healthy adult participants. As previously reported, CNV amplitudes were higher in Go compared to NoGo trials. In addition, event-related spectral power of the Go condition was reduced in the theta to low gamma range compared to the NoGo condition, confirming that preparing to respond is associated with modulation of event-related spectral activity as well as the CNV. Altogether, the impact of the experimental manipulation on both slow event-related potentials and oscillatory EEG activity may reflect coordinated dynamic changes in the excitability of distributed neural networks involved in preparation.

A method for event-related phase/amplitude coupling

Authors:

• Bradley Voytek

• Mark D'Esposito

• Nathan E. Crone

• Robert T. Knight

Date: 2012

DOI: 10.1016/j.neuroimage.2012.09.023

PubMed: 22986076

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Abstract:

Phase/amplitude coupling (PAC) is emerging as an important electrophysiological measure of local and long-distance neuronal communication. Current techniques for calculating PAC provide a numerical index that represents an average value across an arbitrarily long time period. This requires researchers to rely on block design experiments and temporal concatenation at the cost of the sub-second temporal resolution afforded by electrophysiological recordings. Here we present a method for calculating event-related phase/amplitude coupling (ERPAC) designed to capture the temporal evolution of task-related changes in PAC across events or between distant brain regions that is applicable to human or animal electromagnetic recording.