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Lateral prefrontal theta oscillations causally drive a computational mechanism underlying conflict expectation and adaptation
(2024)
María Paz Martínez-Molina
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Gabriela Valdebenito-Oyarzo
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SOTO ICAZA, PATRICIA
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Francisco Zamorano
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Antoni Valero-Cabré
Scopus© Citations 3 8
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Quantitative Susceptibility Mapping MRI in Deep-Brain Nuclei in First-Episode Psychosis
(2023)
Marisleydis García Saborit
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Alejandro Jara
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Néstor Muñoz
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Carlos Milovic
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Angeles Tepper
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Psychosis is related to neurochemical changes in deep-brain nuclei, particularly suggesting dopamine dysfunctions. We used an magnetic resonance imaging-based technique called quantitative susceptibility mapping (QSM) to study these regions in psychosis. QSM quantifies magnetic susceptibility in the brain, which is associated with iron concentrations. Since iron is a cofactor in dopamine pathways and co-localizes with inhibitory neurons, differences in QSM could reflect changes in these processes.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>We scanned 83 patients with first-episode psychosis and 64 healthy subjects. We reassessed 22 patients and 21 control subjects after 3 months. Mean susceptibility was measured in 6 deep-brain nuclei. Using linear mixed models, we analyzed the effect of case-control differences, region, age, gender, volume, framewise displacement (FD), treatment duration, dose, laterality, session, and psychotic symptoms on QSM.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Patients showed a significant susceptibility reduction in the putamen and globus pallidus externa (GPe). Patients also showed a significant R2* reduction in GPe. Age, gender, FD, session, group, and region are significant predictor variables for QSM. Dose, treatment duration, and volume were not predictor variables of QSM.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Reduction in QSM and R2* suggests a decreased iron concentration in the GPe of patients. Susceptibility reduction in putamen cannot be associated with iron changes. Since changes observed in putamen and GPe were not associated with symptoms, dose, and treatment duration, we hypothesize that susceptibility may be a trait marker rather than a state marker, but this must be verified with long-term studies.</jats:p> </jats:sec>
Scopus© Citations 1 1
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Degeneracy in the neurological model of auditory speech repetition
(2023)
Noor Sajid
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GAJARDO VIDAL, ANDREA ELIZABETH
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Justyna O. Ekert
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Diego L. Lorca-Puls
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Thomas M. H. Hope
<jats:title>Abstract</jats:title><jats:p>Both classic and contemporary models of auditory word repetition involve at least four left hemisphere regions: primary auditory cortex for processing sounds; pSTS (within Wernicke’s area) for processing auditory images of speech; pOp (within Broca’s area) for processing motor images of speech; and primary motor cortex for overt speech articulation. Previous functional-MRI (fMRI) studies confirm that auditory repetition activates these regions, in addition to many others. Crucially, however, contemporary models do not specify how regions interact and drive each other during auditory repetition. Here, we used dynamic causal modelling, to test the functional interplay among the four core brain regions during single auditory word and pseudoword repetition. Our analysis is grounded in the principle of degeneracy—i.e., many-to-one structure-function relationships—where multiple neural pathways can execute the same function. Contrary to expectation, we found that, for both word and pseudoword repetition, (i) the effective connectivity between pSTS and pOp was predominantly bidirectional and inhibitory; (ii) activity in the motor cortex could be driven by either pSTS or pOp; and (iii) the latter varied both within and between individuals. These results suggest that different neural pathways can support auditory speech repetition. This degeneracy may explain resilience to functional loss after brain damage.</jats:p>
Scopus© Citations 3 2
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Anatomical dissociation of intracerebral signals for reward and punishment prediction errors in humans
(2021)
Maëlle C. M. Gueguen
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Alizée Lopez-Persem
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BILLEKE BOBADILLA, PABLO ERNESTO
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Jean-Philippe Lachaux
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Sylvain Rheims
<jats:title>Abstract</jats:title><jats:p>Whether maximizing rewards and minimizing punishments rely on distinct brain systems remains debated, given inconsistent results coming from human neuroimaging and animal electrophysiology studies. Bridging the gap across techniques, we recorded intracerebral activity from twenty participants while they performed an instrumental learning task. We found that both reward and punishment prediction errors (PE), estimated from computational modeling of choice behavior, correlate positively with broadband gamma activity (BGA) in several brain regions. In all cases, BGA scaled positively with the outcome (reward or punishment versus nothing) and negatively with the expectation (predictability of reward or punishment). However, reward PE were better signaled in some regions (such as the ventromedial prefrontal and lateral orbitofrontal cortex), and punishment PE in other regions (such as the anterior insula and dorsolateral prefrontal cortex). These regions might therefore belong to brain systems that differentially contribute to the repetition of rewarded choices and the avoidance of punished choices.</jats:p>
Scopus© Citations 48 1
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A functional dissociation of the left frontal regions that contribute to single word production tasks
(2021)
Justyna O. Ekert
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Diego L. Lorca-Puls
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GAJARDO VIDAL, ANDREA ELIZABETH
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Jennifer T. Crinion
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Thomas M.H. Hope
Scopus© Citations 10 2
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Dissociating the functions of three left posterior superior temporal regions that contribute to speech perception and production
(2021)
Justyna O. Ekert
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GAJARDO VIDAL, ANDREA ELIZABETH
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Diego L. Lorca-Puls
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Thomas M.H. Hope
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Fred Dick
Scopus© Citations 11 1
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Multidimensional inhibitory signatures of sentential negation in behavioral variant frontotemporal dementia
(2022)
Mariano N Díaz-Rivera
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Agustina Birba
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Sol Fittipaldi
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Débora Mola
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Yurena Morera
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Processing of linguistic negation has been associated to inhibitory brain mechanisms. However, no study has tapped this link via multimodal measures in patients with core inhibitory alterations, a critical approach to reveal direct neural correlates and potential disease markers.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Here we examined oscillatory, neuroanatomical, and functional connectivity signatures of a recently reported Go/No-go negation task in healthy controls and behavioral variant frontotemporal dementia (bvFTD) patients, typified by primary and generalized inhibitory disruptions. To test for specificity, we also recruited persons with Alzheimer's disease (AD), a disease involving frequent but nonprimary inhibitory deficits.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In controls, negative sentences in the No-go condition distinctly involved frontocentral delta (2–3 Hz) suppression, a canonical inhibitory marker. In bvFTD patients, this modulation was selectively abolished and significantly correlated with the volume and functional connectivity of regions supporting inhibition (e.g. precentral gyrus, caudate nucleus, and cerebellum). Such canonical delta suppression was preserved in the AD group and associated with widespread anatomo-functional patterns across non-inhibitory regions.</jats:p> </jats:sec> <jats:sec> <jats:title>Discussion</jats:title> <jats:p>These findings suggest that negation hinges on the integrity and interaction of spatiotemporal inhibitory mechanisms. Moreover, our results reveal potential neurocognitive markers of bvFTD, opening a new agenda at the crossing of cognitive neuroscience and behavioral neurology.</jats:p> </jats:sec>
Scopus© Citations 18 4
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Dysconnectivity in Schizophrenia Revisited: Abnormal Temporal Organization of Dynamic Functional Connectivity in Patients With a First Episode of Psychosis
(2022)
Juan P Ramirez-Mahaluf
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Ángeles Tepper
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Luz Maria Alliende
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Carlos Mena
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Carmen Paz Castañeda
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background and Hypothesis</jats:title> <jats:p>Abnormal functional connectivity between brain regions is a consistent finding in schizophrenia, including functional magnetic resonance imaging (fMRI) studies. Recent studies have highlighted that connectivity changes in time in healthy subjects. We here examined the temporal changes in functional connectivity in patients with a first episode of psychosis (FEP). Specifically, we analyzed the temporal order in which whole-brain organization states were visited.</jats:p> </jats:sec> <jats:sec> <jats:title>Study Design</jats:title> <jats:p>Two case-control studies, including in each sample a subgroup scanned a second time after treatment. Chilean sample included 79 patients with a FEP and 83 healthy controls. Mexican sample included 21 antipsychotic-naïve FEP patients and 15 healthy controls. Characteristics of the temporal trajectories between whole-brain functional connectivity meta-states were examined via resting-state functional MRI using elements of network science. We compared the cohorts of cases and controls and explored their differences as well as potential associations with symptoms, cognition, and antipsychotic medication doses.</jats:p> </jats:sec> <jats:sec> <jats:title>Study Results</jats:title> <jats:p>We found that the temporal sequence in which patients’ brain dynamics visited the different states was more redundant and segregated. Patients were less flexible than controls in changing their network in time from different configurations, and explored the whole landscape of possible states in a less efficient way. These changes were related to the dose of antipsychotics the patients were receiving. We replicated the relationship with antipsychotic medication in the antipsychotic-naïve FEP sample scanned before and after treatment.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>We conclude that psychosis is related to a temporal disorganization of the brain’s dynamic functional connectivity, and this is associated with antipsychotic medication use.</jats:p> </jats:sec>
Scopus© Citations 17 1
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The role of the inferior parietal lobule in writer’s cramp
(2020)
Shabbir Hussain I Merchant
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Eleni Frangos
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Jacob Parker
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Megan Bradson
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Tianxia Wu
<jats:title>Abstract</jats:title> <jats:p>Humans have a distinguishing ability for fine motor control that is subserved by a highly evolved cortico-motor neuronal network. The acquisition of a particular motor skill involves a long series of practice movements, trial and error, adjustment and refinement. At the cortical level, this acquisition begins in the parieto-temporal sensory regions and is subsequently consolidated and stratified in the premotor-motor cortex. Task-specific dystonia can be viewed as a corruption or loss of motor control confined to a single motor skill. Using a multimodal experimental approach combining neuroimaging and non-invasive brain stimulation, we explored interactions between the principal nodes of the fine motor control network in patients with writer’s cramp and healthy matched controls. Patients and healthy volunteers underwent clinical assessment, diffusion-weighted MRI for tractography, and functional MRI during a finger tapping task. Activation maps from the task-functional MRI scans were used for target selection and neuro-navigation of the transcranial magnetic stimulation. Single- and double-pulse TMS evaluation included measurement of the input-output recruitment curve, cortical silent period, and amplitude of the motor evoked potentials conditioned by cortico-cortical interactions between premotor ventral (PMv)-motor cortex (M1), anterior inferior parietal lobule (aIPL)-M1, and dorsal inferior parietal lobule (dIPL)-M1 before and after inducing a long term depression-like plastic change to dIPL node with continuous theta-burst transcranial magnetic stimulation in a randomized, sham-controlled design. Baseline dIPL-M1 and aIPL-M1 cortico-cortical interactions were facilitatory and inhibitory, respectively, in healthy volunteers, whereas the interactions were converse and significantly different in writer’s cramp. Baseline PMv-M1 interactions were inhibitory and similar between the groups. The dIPL-PMv resting state functional connectivity was increased in patients compared to controls, but no differences in structural connectivity between the nodes were observed. Cortical silent period was significantly prolonged in writer’s cramp. Making a long term depression-like plastic change to dIPL node transformed the aIPL-M1 interaction to inhibitory (similar to healthy volunteers) and cancelled the PMv-M1 inhibition only in the writer’s cramp group. These findings suggest that the parietal multimodal sensory association region could have an aberrant downstream influence on the fine motor control network in writer’s cramp, which could be artificially restored to its normal function.</jats:p>
Scopus© Citations 33 1
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Interoception Primes Emotional Processing: Multimodal Evidence from Neurodegeneration
(2021)
Paula C. Salamone
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Agustina Legaz
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Lucas Sedeño
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Sebastián Moguilner
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Matías Fraile-Vazquez
7Scopus© Citations 80

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