Can pathway-specific LFPs be obtained in cytoarchitectonically complex structures?

Makarova, Julia; Ortuño, Tania; Korovaichuk, A.; Cudeiro, Javier; Makarov, Valeri A.; Rivadulla, Casto; Herreras, Óscar

doi:10.3389/fnsys.2014.00066

Cited by 11 publications

(16 citation statements)

References 17 publications

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“…Also, the LFPs appear to irradiate asymmetrically toward the open end, a sort of anisotropic effect that should be taken in account when estimating the location and intensity of deep sources from scalp recordings. Similar effects can be expected in other brain structures, such as the cortical gyri, the cerebellum and the curved lateral geniculate nucleus of primates (Makarova et al, 2014). …”

Section: Common Misconceptions Around Local Field Potentialssupporting

confidence: 69%

Local Field Potentials: Myths and Misunderstandings

Herreras

2016

Front. Neural Circuits

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The intracerebral local field potential (LFP) is a measure of brain activity that reflects the highly dynamic flow of information across neural networks. This is a composite signal that receives contributions from multiple neural sources, yet interpreting its nature and significance may be hindered by several confounding factors and technical limitations. By and large, the main factor defining the amplitude of LFPs is the geometry of the current sources, over and above the degree of synchronization or the properties of the media. As such, similar levels of activity may result in potentials that differ in several orders of magnitude in different populations. The geometry of these sources has been experimentally inaccessible until intracerebral high density recordings enabled the co-activating sources to be revealed. Without this information, it has proven difficult to interpret a century's worth of recordings that used temporal cues alone, such as event or spike related potentials and frequency bands. Meanwhile, a collection of biophysically ill-founded concepts have been considered legitimate, which can now be corrected in the light of recent advances. The relationship of LFPs to their sources is often counterintuitive. For instance, most LFP activity is not local but remote, it may be larger further from rather than close to the source, the polarity does not define its excitatory or inhibitory nature, and the amplitude may increase when source's activity is reduced. As technological developments foster the use of LFPs, the time is now ripe to raise awareness of the need to take into account spatial aspects of these signals and of the errors derived from neglecting to do so.

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Section: Common Misconceptions Around Local Field Potentialssupporting

confidence: 69%

Local Field Potentials: Myths and Misunderstandings

Herreras

2016

Front. Neural Circuits

Self Cite

263

244

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“…1B ). ICA has been used in EEG analysis to successfully identify and remove distant signal sources such as eye movement and EKG artifact ( Jung et al, 1998a , 1998b ) as well as in the analysis of LFP signals in anesthetized animals to remove distant signal sources ( Korovaichuk et al, 2010 ; Makarova et al, 2014 ). The successful identification of underlying sources using ICA requires simultaneous recording of multiple LFPs across multiple brain regions.…”

Section: Resultsmentioning

confidence: 99%

“…ICA has been widely applied in human EEG literature to successfully identify eye movement or electrocardiogram (EKG) artifacts ( Jung et al, 1998a , 1998b ). ICA has also been applied to LFP recordings in anesthetized animals, for example, from the rat hippocampus, to exclude distant signals sources and to isolate the contributions of distinct input pathways to hippocampal LFPs ( Fernandez-Ruiz et al, 2013 ; Herreras et al, 2015 ; Korovaichuk et al, 2010 ; Makarov et al, 2010 ; Makarova et al, 2014 ; Martín-Vázquez et al, 2013 ). The current study extends these previous efforts and applies ICA to analyze LFPs recorded in animals performing behavioral tasks.…”

Section: Introductionmentioning

confidence: 99%

Unmasking local activity within local field potentials (LFPs) by removing distal electrical signals using independent component analysis

Whitmore

Lin

2016

NeuroImage

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Local field potentials (LFPs) are commonly thought to reflect the aggregate dynamics in local neural circuits around recording electrodes. However, we show that when LFPs are recorded in awake behaving animals against a distal reference on the skull as commonly practiced, LFPs are significantly contaminated by non-local and non-neural sources arising from the reference electrode and from movement-related noise. In a data set with simultaneously recorded LFPs and electroencephalograms (EEGs) across multiple brain regions while rats perform an auditory oddball task, we used independent component analysis (ICA) to identify signals arising from electrical reference and from volume-conducted noise based on their distributed spatial pattern across multiple electrodes and distinct power spectral features. These sources of distal electrical signals collectively accounted for 23–77% of total variance in unprocessed LFPs, as well as most of the gamma oscillation responses to the target stimulus in EEGs. Gamma oscillation power was concentrated in volume-conducted noise and was tightly coupled with the onset of licking behavior, suggesting a likely origin of muscle activity associated with body movement or orofacial movement. The removal of distal signal contamination also selectively reduced correlations of LFP/EEG signals between distant brain regions but not within the same region. Finally, the removal of contamination from distal electrical signals preserved an event-related potential (ERP) response to auditory stimuli in the frontal cortex and also increased the coupling between the frontal ERP amplitude and neuronal activity in the basal forebrain, supporting the conclusion that removing distal electrical signals unmasked local activity within LFPs. Together, these results highlight the significant contamination of LFPs by distal electrical signals and caution against the straightforward interpretation of unprocessed LFPs. Our results provide a principled approach to identify and remove such contamination to unmask local LFPs.

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“…While the biophysical basis of LFPs has been well described (Elul 1971;Nunez and Srinivasan 2006), their practical use has been rather limited due to the practical difficulties to recover pathway-specific synaptic currents from mixed LFPs. Recently, the disentanglement of LFPs into pathway-specific components by ICA has proven efficient in different structures and species (Benito et al 2014;Makarova et al 2014). This permitted us to extract the CA3-originated LFPs from different targets.…”

Section: Identification Of Ca3-specific Lfpsmentioning

confidence: 99%

Diversity of LFPs Activated in Different Target Regions by a Common CA3 Input

et al. 2015

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Identifying the pathways contributing to local field potential (LFP) events and oscillations is essential to determine whether synchronous interregional patterns indicate functional connectivity. Here, we studied experimentally and numerically how different target structures receiving input from a common population shape their LFPs. We focused on the bilateral CA3 that sends gamma-paced excitatory packages to the bilateral CA1, the lateral septum, and itself (recurrent input). The CA3-specific contribution was isolated from multisite LFPs in target regions using spatial discrimination techniques. We found strong modulation of LFPs by target-specific features, including the morphology and population arrangement of cells, the timing of CA3 inputs, volume conduction from nearby targets, and co-activated inhibition. Jointly they greatly affect the LFP amplitude, profile, and frequency characteristics. For instance, ipsilateral (Schaffer) LFPs occluded contralateral ones, and septal LFPs arise mostly from remote sources while local contribution from CA3 input was minor. In the CA3 itself, gamma waves have dual origin from local networks: in-phase excitatory and nearly antiphase inhibitory. Also, waves may have different duration and varying phase in different targets. These results indicate that to explore the cellular basis of LFPs and the functional connectivity between structures, besides identifying the origin population/s, target modifiers should be considered.

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Can pathway-specific LFPs be obtained in cytoarchitectonically complex structures?

Cited by 11 publications

References 17 publications

Local Field Potentials: Myths and Misunderstandings

Local Field Potentials: Myths and Misunderstandings

Unmasking local activity within local field potentials (LFPs) by removing distal electrical signals using independent component analysis

Diversity of LFPs Activated in Different Target Regions by a Common CA3 Input

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