Biology subjects

Martin-Buro, M. C.

Publications and source records attributed to Martin-Buro, M. C..

4 recordsLinked to original sources

bioRxiv2025

Multivariate pattern analysis reveals resting-state EEG biomarkers in fibromyalgia

Fibromyalgia involves widespread musculoskeletal pain and hypersensitivity, often accompanied by neurological, cognitive, and affective disturbances. Resting-state electroencephalography studies have revealed abnormal brain activity in chronic pain conditions, with anxiety and symptom duration potentially exacerbating these alterations. This study applied multivariate pattern analysis to differentiate inter-trial resting-state electroencephalography signals between fibromyalgia patients and healthy controls across frequency bands associated with pain processing, incorporating state and trait anxiety scores. It also examined differences between patients with short and long duration symptoms and identified the most relevant scalp regions contributing to the models. Fifty-one female participants (25 fibromyalgia patients, 26 controls; aged 35-65) were included. Patients were classified into short-term (12) and long-term (13) groups. Normalized power spectral density values were extracted from electroencephalography data and used to train machine learning classifiers, with Haufe-transformed weights computed to determine key scalp contributions. The models distinguished patients from controls with area under the curve values exceeding 0.75 across all frequency bands, reaching 0.99 in beta and gamma bands when anxiety was included. Symptom duration was also a relevant factor, as the model differentiated short-from long-term fibromyalgia patients with area under the curve values up to 0.96 in beta and gamma bands. Alterations in theta power within frontal and parietal regions, along with frequency-specific contributions, highlight disrupted pain processing in fibromyalgia and suggest cumulative effects of prolonged symptom duration. Future resting-state studies leveraging multivariate pattern analysis may support the development of potential biomarkers to improve diagnosis and guide treatment strategies in clinical settings.

neuroscience↗

bioRxiv2020

The hippocampus as the switchboard between perception and memory

Adaptive memory recall requires a rapid and flexible switch from external perceptual reminders to internal mnemonic representations. However, owing to the limited temporal or spatial resolution of brain imaging modalities used in isolation, the hippocampal-cortical dynamics supporting this process remain unknown. We thus employed an object-scene cued recall paradigm across two studies, including intracranial Electroencephalography (iEEG) and high-density scalp EEG. First, a sustained increase in hippocampal high gamma power (60-110 Hz) emerged 500 ms after cue onset and distinguished successful vs. unsuccessful recall. This increase in gamma power for successful recall was followed by a decrease in hippocampal alpha power (8-12 Hz). Intriguingly, the hippocampal gamma power increase marked the moment at which extrahippocampal activation patterns shifted from perceptual cue towards mnemonic target representations. In parallel, source-localised EEG alpha power revealed that the recall signal progresses from hippocampus to posterior parietal cortex and then to medial prefrontal cortex. Together, these results identify the hippocampus as the switchboard between perception and memory and elucidate the ensuing hippocampal-cortical dynamics supporting the recall process. SignificanceHow do we adaptively switch from perceiving the external world to retrieving goal-relevant internal memories? To tackle this question, we used - in a cued-recall paradigm - direct intracranial recordings from the human hippocampus complemented by high-density scalp Electroencephalography (EEG). We found that a hippocampal signal ~500 ms after a perceptual cue marks the conversion from external (perceptual) to internal (mnemonic) representations. This sets in motion a recall cascade involving posterior parietal and medial prefrontal cortex, revealed via source-localised and time-resolved EEG alpha power. Together, these results unveil the hippocampal-cortical dynamics supporting rapid and flexible memory recall.

neuroscience↗

bioRxiv2020

Disentangling the roles of neocortical alpha/beta and hippocampal theta/gamma activity in human episodic memory

To form an episodic memory, we must first process a vast amount of sensory information about a to-be-encoded event and then bind these sensory representations together to form a coherent memory. While these two cognitive capabilities are thought to have two distinct neural origins, with neocortical alpha/beta oscillations supporting information representation and hippocampal theta-gamma phase-amplitude coupling supporting mnemonic binding, evidence for a dissociation between these two neural markers is conspicuously absent. To address this, seventeen human participants completed a sequence-learning task that first involved processing information about three stimuli, and then binding these stimuli together into a coherent memory trace, all the while undergoing MEG recordings. We found that decreases in neocortical alpha/beta power during sequence perception, but not mnemonic binding, correlated with enhanced memory performance. Hippocampal theta/gamma phase-amplitude coupling, however, showed the opposite pattern; increases during mnemonic binding (but not sequence perception) correlated with enhanced memory performance. These results demonstrate that memory-related decreases in neocortical alpha/beta power and memory-related increases in hippocampal theta/gamma phase-amplitude coupling arise at distinct stages of the memory formation process. We speculate that this temporal dissociation reflects a functional dissociation in which neocortical alpha/beta oscillations could support the processing of incoming information relevant to the memory, while hippocampal theta-gamma phase-amplitude coupling could support the binding of this information into a coherent memory trace.

neuroscience↗

bioRxiv2019

Alpha rhythms reveal when, where and how memories are retrieved

Our memories for past experiences can range from vague recognition to full-blown recall of associated details. Neuroimaging research has tried to understand the brain mechanisms underlying qualitatively different memories for decades (Yonelinas, 2002). On the one hand, Electroencephalography (EEG) has shown that recall signals unfold a few hundred milliseconds after simple recognition and are hallmarked by sustained voltage deflections over left posterior sensors (Herron, 2007; Johansson & Mecklinger, 2003; Mecklinger, Rosburg, & Johansson, 2016; Rugg & Curran, 2007). However, sensor-based analyses only provide limited insights into the supporting brain networks. On the other hand, functional magnetic resonance imaging (fMRI) has revealed a core recollection network centred on posterior parietal and medial temporal lobe (MTL) regions (Hayama, Vilberg, & Rugg, 2012; Johnson, Suzuki, & Rugg, 2013; King, de Chastelaine, Elward, Wang, & Rugg, 2015; Rugg, Johnson, & Uncapher, 2015; Rugg & Vilberg, 2013; Thakral, Benoit, & Schacter, 2017). However, due to the relatively poor time resolution of fMRI, the temporal dynamics of these regions during retrieval remain largely unknown. In order to overcome these modality-specific limitations, we here used Magnetoencephalography (MEG) in a verbal episodic memory paradigm assessing correct rejection (CR) of lures, item recognition (IR) of old words and associative recall (AR) of paired target words. We found that power decreases in the alpha frequency band (10-12 Hz) systematically track different mnemonic outcomes in both time and space: Over left posterior sensors, alpha power decreased in a stepwise fashion from 500 ms onward, first from CR to IR and then from IR to AR. When projecting alpha power into source space, the core recollection network known from fMRI studies emerged, including posterior parietal cortex (PPC) and hippocampus. While PPC showed a linear change across conditions, hippocampal effects were specific to recall. Critically, the hippocampal recall effect emerged [~]200 ms before the PPC recall effect, suggesting a bottom-up recall signal from hippocampus to PPC. Our data thus link engagement of the core recollection network to the temporal dynamics of episodic memory and suggest that alpha rhythms constitute a fundamental oscillatory mechanism revealing when, where and how our memories are retrieved.\n\nHighlightsO_LIAlpha rhythms distinguish between different retrieval outcomes\nC_LIO_LIAlpha power time courses track item recognition and associative recall\nC_LIO_LISource alpha power decreases track the fMRI core recollection network\nC_LIO_LIHippocampal recall signal precedes parietal signal\nC_LI

neuroscience↗