Spatiotemporal structure of sensory-evoked and spontaneous activity revealed by mesoscale imaging in anesthetized and awake mice

AbstractBrain activity propagates across the cortex in diverse spatiotemporal patterns, both as a response to sensory stimulation and during spontaneous activity. Despite been extensively studied, the relationship between the characteristics of such patterns during spontaneous and evoked activity is not completely understood. To investigate this relationship, we compared visual, auditory, and tactile evoked activity patterns elicited with different stimulus strengths and spontaneous activity motifs in lightly anesthetized and awake mice using mesoscale wide-field voltage-sensitive dye and glutamate imaging respectively. The characteristics of cortical activity that we compared include amplitude, speed, direction, and complexity of propagation trajectories in spontaneous and evoked activity patterns. We found that the complexity of the propagation trajectories of spontaneous activity, quantified as their fractal dimension, is higher than the one from sensory evoked responses. Moreover, the speed and direction of propagation, are modulated by the amplitude during both, spontaneous and evoked activity. Finally, we found that spontaneous activity had similar amplitude and speed when compared to evoked activity elicited with low stimulus strengths. However, this similarity gradually decreased when the strength of stimuli eliciting evoked responses increased. Altogether, these findings are consistent with the fact that even primary sensory areas receive widespread inputs from other cortical regions, and that, during rest, the cortex tends to reactivate traces of complex, multi-sensory experiences that may have occurred in a range of different behavioural contexts.

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Sodium-Calcium Exchanger Mediates Sensory-Evoked Glial Calcium Transients in the Developing Retinotectal System

10.1101/2020.11.14.383125 ◽

2020 ◽

Author(s):

Nicholas J. Benfey ◽

Vanessa J. Li ◽

Anne Schohl ◽

Edward S. Ruthazer

Keyword(s):

Visual Stimulation ◽

Activity Patterns ◽

Sensory Stimulation ◽

Calcium Transients ◽

Evoked Responses ◽

Sodium Calcium Exchanger ◽

Sensory Stimuli ◽

Sodium Calcium ◽

Evoked Activity ◽

Sensory Evoked

AbstractVarious types of sensory stimuli have been shown to induce calcium elevations in glia. However, a mechanistic understanding of the signalling pathways mediating sensory-evoked activity in glia in intact animals is still emerging. Here we demonstrate that during early development of the Xenopus laevis visual system, radial astrocytes in the optic tectum are highly responsive to sensory stimulation. Calcium transients occur spontaneously in radial astrocytes at rest and are abolished by silencing neuronal activity with tetrodotoxin. Visual stimulation drives temporally correlated increases in the activity patterns of neighbouring radial astrocytes. Following blockade of all glutamate receptors, visually-evoked calcium activity in radial astrocytes is enhanced, rather than suppressed, while the additional blockade of either glutamate transporters or sodium-calcium exchangers (NCX) fully prevents visually-evoked responses. Additionally, we demonstrate that blockade of NCX alone is sufficient to prevent visually-evoked responses in radial astrocytes, highlighting a pivotal role for NCX in glia during development.

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Spontaneous activity competes externally evoked responses in sensory cortex

10.1101/2020.08.18.256206 ◽

2020 ◽

Author(s):

Golan. Karvat ◽

Mansour Alyahyay ◽

Ilka Diester

Keyword(s):

Spontaneous Activity ◽

Brain Activity ◽

Detection Algorithm ◽

Dynamic State ◽

Evoked Responses ◽

Beta Band ◽

Beta Power ◽

Rat Somatosensory Cortex ◽

Sensory Evoked ◽

External Stimuli

SummaryThe functional role of spontaneous brain activity, especially in relation to external events, is a longstanding key question in neuroscience. Intrinsic and externally-evoked activities were suggested to be anticorrelated, yet inferring an antagonistic mechanism between them remains a challenge. Here, we used beta-band (15-30 Hz) power as a proxy of spontaneous activity in the rat somatosensory cortex during a detection task. Beta-power anticorrelated with sensory-evoked-responses, and high rates of spontaneously occurring beta-bursts predicted reduced detection. By applying a burst-rate detection algorithm in real-time and trial-by-trial stimulus-intensity adjustment, this influence could be counterbalanced. Mechanistically, bursts in all bands indicated transient synchronization of cell assemblies, but only beta-bursts were followed by a reduction in firing-rate. Our findings reveal that spontaneous beta-bursts reflect a dynamic state that competes with external stimuli.

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Magnetoencephalography in Alzheimer Disease

Fifty Years of Magnetoencephalography ◽

10.1093/oso/9780190935689.003.0025 ◽

2020 ◽

pp. 390-402

Author(s):

David López-Sanz ◽

Jaisalmer de Frutos-Lucas ◽

Gianluca Susi ◽

Fernando Maestú

Keyword(s):

Alzheimer Disease ◽

Spontaneous Activity ◽

Brain Mapping ◽

Brain Activity ◽

Activity Patterns ◽

Alzheimer’S Dementia ◽

Alzheimer's Dementia ◽

Brain Signals ◽

Epilepsy Localization ◽

Monitoring Progress

There are two basic ways Magnetoencephalography (MEG) has been applied. The most typical way is recording brain signals related to specific stimuli and tasks or signals indicative of focal pathology as in presurgical brain mapping and epilepsy localization. The second way is recording patterns of spontaneous activity characteristic of particular states or traits. An example of the latter application is described in this chapter that details efforts of deriving brain activity patterns characteristic of Alzheimer’s dementia. The derivation of such patterns will be of great value in diagnosis, prognosis, as well as monitoring progress (or the process of amelioration) of diseases.

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Cholinergic modulation of sensory processing in awake mouse cortex

Scientific Reports ◽

10.1038/s41598-021-96696-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Javier Jimenez-Martin ◽

Daniil Potapov ◽

Kay Potapov ◽

Thomas Knöpfel ◽

Ruth M. Empson

Keyword(s):

Pyramidal Neurons ◽

Brain Activity ◽

Critical Role ◽

Sensory Information ◽

Sensory Stimulation ◽

Cholinergic Modulation ◽

Neuronal Populations ◽

Mouse Cortex ◽

Cortical Pyramidal Neurons ◽

Sensory Evoked

AbstractCholinergic modulation of brain activity is fundamental for awareness and conscious sensorimotor behaviours, but deciphering the timing and significance of acetylcholine actions for these behaviours is challenging. The widespread nature of cholinergic projections to the cortex means that new insights require access to specific neuronal populations, and on a time-scale that matches behaviourally relevant cholinergic actions. Here, we use fast, voltage imaging of L2/3 cortical pyramidal neurons exclusively expressing the genetically-encoded voltage indicator Butterfly 1.2, in awake, head-fixed mice, receiving sensory stimulation, whilst manipulating the cholinergic system. Altering muscarinic acetylcholine function re-shaped sensory-evoked fast depolarisation and subsequent slow hyperpolarisation of L2/3 pyramidal neurons. A consequence of this re-shaping was disrupted adaptation of the sensory-evoked responses, suggesting a critical role for acetylcholine during sensory discrimination behaviour. Our findings provide new insights into how the cortex processes sensory information and how loss of acetylcholine, for example in Alzheimer’s Disease, disrupts sensory behaviours.

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Spontaneous Brain Activity Predicts Task-Evoked Activity During Animate Versus Inanimate Touch

Cerebral Cortex ◽

10.1093/cercor/bhy340 ◽

2019 ◽

Vol 29 (11) ◽

pp. 4628-4645 ◽

Cited By ~ 12

Author(s):

Andrea Scalabrini ◽

Sjoerd J H Ebisch ◽

Zirui Huang ◽

Simone Di Plinio ◽

Mauro Gianni Perrucci ◽

...

Keyword(s):

Anterior Cingulate Cortex ◽

Spontaneous Activity ◽

Brain Activity ◽

Temporal Structure ◽

Cingulate Cortex ◽

Anterior Cingulate ◽

Scale Free ◽

Spontaneous Brain Activity ◽

Posterior Insula ◽

Evoked Activity

Abstract The spontaneous activity of the brain is characterized by an elaborate temporal structure with scale-free properties as indexed by the power law exponent (PLE). We test the hypothesis that spontaneous brain activity modulates task-evoked activity during interactions with animate versus inanimate stimuli. For this purpose, we developed a paradigm requiring participants to actively touch either animate (real hand) or inanimate (mannequin hand) stimuli. Behaviorally, participants perceived the animate target as closer in space, temporally more synchronous with their own self, and more personally relevant, compared with the inanimate. Neuronally, we observed a modulation of task-evoked activity by animate versus inanimate interactions in posterior insula, in medial prefrontal cortex, comprising anterior cingulate cortex, and in medial superior frontal gyrus. Among these regions, an increased functional connectivity was shown between posterior insula and perigenual anterior cingulate cortex (PACC) during animate compared with inanimate interactions and during resting state. Importantly, PLE during spontaneous brain activity in PACC correlated positively with PACC task-evoked activity during animate versus inanimate stimuli. In conclusion, we demonstrate that brain spontaneous activity in PACC can be related to the distinction between animate and inanimate stimuli and thus might be specifically tuned to align our brain with its animate environment.

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Visual Number Beats Abstract Numerical Magnitude: Format-dependent Representation of Arabic Digits and Dot Patterns in Human Parietal Cortex

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00787 ◽

2015 ◽

Vol 27 (7) ◽

pp. 1376-1387 ◽

Cited By ~ 34

Author(s):

Jessica Bulthé ◽

Bert De Smedt ◽

Hans P. Op de Beeck

Keyword(s):

Activity Pattern ◽

Numerical Cognition ◽

Brain Activity ◽

Activity Patterns ◽

Brain Regions ◽

Numerical Magnitude ◽

Visual Objects ◽

Arabic Digits ◽

The One ◽

Object Cognition

In numerical cognition, there is a well-known but contested hypothesis that proposes an abstract representation of numerical magnitude in human intraparietal sulcus (IPS). On the other hand, researchers of object cognition have suggested another hypothesis for brain activity in IPS during the processing of number, namely that this activity simply correlates with the number of visual objects or units that are perceived. We contrasted these two accounts by analyzing multivoxel activity patterns elicited by dot patterns and Arabic digits of different magnitudes while participants were explicitly processing the represented numerical magnitude. The activity pattern elicited by the digit “8” was more similar to the activity pattern elicited by one dot (with which the digit shares the number of visual units but not the magnitude) compared to the activity pattern elicited by eight dots, with which the digit shares the represented abstract numerical magnitude. A multivoxel pattern classifier trained to differentiate one dot from eight dots classified all Arabic digits in the one-dot pattern category, irrespective of the numerical magnitude symbolized by the digit. These results were consistently obtained for different digits in IPS, its subregions, and many other brain regions. As predicted from object cognition theories, the number of presented visual units forms the link between the parietal activation elicited by symbolic and nonsymbolic numbers. The current study is difficult to reconcile with the hypothesis that parietal activation elicited by numbers would reflect a format-independent representation of number.

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Cross-domain effect of pitch processing in lexical and melodic contexts reflected by non-musicians: An MEG study

10.37716/hbab.2020010701 ◽

2020 ◽

pp. 85-90

Author(s):

Zhaowei Liu ◽

◽

Yun Nan ◽

Lingxi Lu ◽

Wei Cui ◽

...

Keyword(s):

Brain Activity ◽

Activity Patterns ◽

Music Training ◽

Pitch Processing ◽

Cross Domain ◽

Musical Pitch ◽

Language And Music ◽

Perceptual Abilities ◽

Cortical Regions ◽

Brain Behavior

The pitch processing of language and music is generally considered engaging overlapped neural correlates. Previous studies on musicians showed that the ability of pitch processing in music could be transferred to language. It is known that music training can facilitate neural processing of speech, however, the underlying neural mechanisms of pitch processing of language and music are not fully understood, especially in non-musicians. Using magnetoencephalography, we presented a pitch anomaly paradigm which consists of language/music phrases ending in either congruous or incongruous tones/pitches to non-musicians. We found the distinctive brain activity patterns in two groups with high and low musical pitch perceptual abilities. The brain-behavior results showed a positive correlation between the performance of musical pitch tasks and the activation of the left frontotemporal cortical regions elicited by lexical tones. Our results suggested that the cross-domain effect of language and music could be generalized to people without formal music training.

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Spatial band-pass filtering aids decoding musical genres from auditory cortex 7T fMRI

F1000Research ◽

10.12688/f1000research.13689.1 ◽

2018 ◽

Vol 7 ◽

pp. 142 ◽

Cited By ~ 3

Author(s):

Ayan Sengupta ◽

Stefan Pollmann ◽

Michael Hanke

Keyword(s):

Auditory Cortex ◽

Brain Activity ◽

Activity Patterns ◽

Primary Auditory Cortex ◽

Sensory Stimulation ◽

Spatial Filtering ◽

Visual Orientation ◽

Fine Grained ◽

Musical Genres ◽

7T Fmri

Spatial filtering strategies, combined with multivariate decoding analysis of BOLD images, have been used to investigate the nature of the neural signal underlying the discriminability of brain activity patterns evoked by sensory stimulation -- primarily in the visual cortex. Reported evidence indicates that such signals are spatially broadband in nature, and are not primarily comprised of fine-grained activation patterns. However, it is unclear whether this is a general property of the BOLD signal, or whether it is specific to the details of employed analyses and stimuli. Here we performed an analysis of publicly available, high-resolution 7T fMRI on the response BOLD response to musical genres in primary auditory cortex that matches a previously conducted study on decoding visual orientation from V1. The results show that the pattern of decoding accuracies with respect to different types and levels of spatial filtering is comparable to that obtained from V1, despite considerable differences in the respective cortical circuitry.

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Quantitative Analysis and Biophysically Realistic Neural Modeling of the MEG Mu Rhythm: Rhythmogenesis and Modulation of Sensory-Evoked Responses

Journal of Neurophysiology ◽

10.1152/jn.00535.2009 ◽

2009 ◽

Vol 102 (6) ◽

pp. 3554-3572 ◽

Cited By ~ 119

Author(s):

Stephanie R. Jones ◽

Dominique L. Pritchett ◽

Michael A. Sikora ◽

Steven M. Stufflebeam ◽

Matti Hämäläinen ◽

...

Keyword(s):

Neural Model ◽

Evoked Responses ◽

Mu Rhythm ◽

Thalamic Nuclei ◽

Localized Source ◽

Cortical Oscillations ◽

Alpha 7 ◽

Evoked Activity ◽

Sensory Evoked ◽

The Impact

Variations in cortical oscillations in the alpha (7–14 Hz) and beta (15–29 Hz) range have been correlated with attention, working memory, and stimulus detection. The mu rhythm recorded with magnetoencephalography (MEG) is a prominent oscillation generated by Rolandic cortex containing alpha and beta bands. Despite its prominence, the neural mechanisms regulating mu are unknown. We characterized the ongoing MEG mu rhythm from a localized source in the finger representation of primary somatosensory (SI) cortex. Subjects showed variation in the relative expression of mu-alpha or mu-beta, which were nonoverlapping for roughly 50% of their respective durations on single trials. To delineate the origins of this rhythm, a biophysically principled computational neural model of SI was developed, with distinct laminae, inhibitory and excitatory neurons, and feedforward (FF, representative of lemniscal thalamic drive) and feedback (FB, representative of higher-order cortical drive or input from nonlemniscal thalamic nuclei) inputs defined by the laminar location of their postsynaptic effects. The mu-alpha component was accurately modeled by rhythmic FF input at approximately 10-Hz. The mu-beta component was accurately modeled by the addition of approximately 10-Hz FB input that was nearly synchronous with the FF input. The relative dominance of these two frequencies depended on the delay between FF and FB drives, their relative input strengths, and stochastic changes in these variables. The model also reproduced key features of the impact of high prestimulus mu power on peaks in SI-evoked activity. For stimuli presented during high mu power, the model predicted enhancement in an initial evoked peak and decreased subsequent deflections. In agreement, the MEG-evoked responses showed an enhanced initial peak and a trend to smaller subsequent peaks. These data provide new information on the dynamics of the mu rhythm in humans and the model provides a novel mechanistic interpretation of this rhythm and its functional significance.

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Decoding Covert Speech From EEG-A Comprehensive Review

Frontiers in Neuroscience ◽

10.3389/fnins.2021.642251 ◽

2021 ◽

Vol 15 ◽

Author(s):

Jerrin Thomas Panachakel ◽

Angarai Ganesan Ramakrishnan

Keyword(s):

Formal Education ◽

Vocal Communication ◽

Brain Activity ◽

Activity Patterns ◽

Machine Learning Algorithms ◽

Human Beings ◽

Natural Form ◽

Practical Applications ◽

The One

Over the past decade, many researchers have come up with different implementations of systems for decoding covert or imagined speech from EEG (electroencephalogram). They differ from each other in several aspects, from data acquisition to machine learning algorithms, due to which, a comparison between different implementations is often difficult. This review article puts together all the relevant works published in the last decade on decoding imagined speech from EEG into a single framework. Every important aspect of designing such a system, such as selection of words to be imagined, number of electrodes to be recorded, temporal and spatial filtering, feature extraction and classifier are reviewed. This helps a researcher to compare the relative merits and demerits of the different approaches and choose the one that is most optimal. Speech being the most natural form of communication which human beings acquire even without formal education, imagined speech is an ideal choice of prompt for evoking brain activity patterns for a BCI (brain-computer interface) system, although the research on developing real-time (online) speech imagery based BCI systems is still in its infancy. Covert speech based BCI can help people with disabilities to improve their quality of life. It can also be used for covert communication in environments that do not support vocal communication. This paper also discusses some future directions, which will aid the deployment of speech imagery based BCI for practical applications, rather than only for laboratory experiments.

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