Imperial College London

DrInesRibeiro Violante

Faculty of MedicineDepartment of Medicine

Honorary Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7994i.violante

 
 
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Location

 

Burlington DanesHammersmith Campus

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Summary

 

Publications

Publication Type
Year
to

34 results found

Hampshire A, Daws RE, Das Neves I, Soreq E, Sandrone S, Violante IRet al., 2019, Probing cortical and sub-cortical contributions to instruction-based learning: Regional specialisation and global network dynamics, NEUROIMAGE, Vol: 192, Pages: 88-100, ISSN: 1053-8119

JOURNAL ARTICLE

Li LM, Violante IR, Leech R, Ross E, Hampshire A, Opitz A, Rothwell JC, Carmichael DW, Sharp DJet al., 2019, Brain state and polarity dependent modulation of brain networks by transcranial direct current stimulation, HUMAN BRAIN MAPPING, Vol: 40, Pages: 904-915, ISSN: 1065-9471

JOURNAL ARTICLE

Li LM, Violante IR, Leech R, Hampshire A, Opitz A, McArthur D, Carmichael DW, Sharp DJet al., 2019, Cognitive enhancement with Salience Network electrical stimulation is influenced by network structural connectivity, NEUROIMAGE, Vol: 185, Pages: 425-433, ISSN: 1053-8119

JOURNAL ARTICLE

d'Almeida OC, Violante IR, Quendera B, Castelo-Branco Met al., 2018, Mitochondrial pathophysiology beyond the retinal ganglion cell: occipital GABA is decreased in autosomal dominant optic neuropathy, GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY, Vol: 256, Pages: 2341-2348, ISSN: 0721-832X

JOURNAL ARTICLE

Pereira AC, Violante IR, Mouga S, Oliveira G, Castelo-Branco Met al., 2018, Medial Frontal Lobe Neurochemistry in Autism Spectrum Disorder is Marked by Reduced N-Acetylaspartate and Unchanged Gamma-Aminobutyric Acid and Glutamate plus Glutamine Levels, JOURNAL OF AUTISM AND DEVELOPMENTAL DISORDERS, Vol: 48, Pages: 1467-1482, ISSN: 0162-3257

JOURNAL ARTICLE

Lorenz R, Violante IR, Monti RP, Montana G, Hampshire A, Leech Ret al., 2018, Dissociating frontoparietal brain networks with neuroadaptive Bayesian optimization, NATURE COMMUNICATIONS, Vol: 9, ISSN: 2041-1723

JOURNAL ARTICLE

Silva G, Duarte IC, Bernardino I, Marques T, Violante IR, Castelo-Branco Met al., 2018, Oscillatory motor patterning is impaired in neurofibromatosis type 1: a behavioural, EEG and fMRI study, JOURNAL OF NEURODEVELOPMENTAL DISORDERS, Vol: 10, ISSN: 1866-1947

JOURNAL ARTICLE

Datta G, Violante IR, Scott G, Zimmerman K, Santos-Ribeiro A, Rabiner EA, Gunn RN, Malik O, Ciccarelli O, Nicholas R, Matthews PMet al., 2017, Translocator positron-emission tomography and magnetic resonance spectroscopic imaging of brain glial cell activation in multiple sclerosis, MULTIPLE SCLEROSIS JOURNAL, Vol: 23, Pages: 1469-1478, ISSN: 1352-4585

JOURNAL ARTICLE

Goncalves J, Violante IR, Sereno J, Leitao RA, Cai Y, Abrunhosa A, Silva AP, Silva AJ, Castelo-Branco Met al., 2017, Testing the excitation/inhibition imbalance hypothesis in a mouse model of the autism spectrum disorder: in vivo neurospectroscopy and molecular evidence for regional phenotypes, MOLECULAR AUTISM, Vol: 8, ISSN: 2040-2392

JOURNAL ARTICLE

Li L, Violante I, Leech R, Ross E, Hampshire A, Opitz A, Rothwell J, Carmichael D, Sharp Det al., 2017, Brain state and polarity dependent modulation of brain networks by transcranial direct current stimulation

Transcranial direct current stimulation (TDCS) has been widely used to improve cognitive function. However, current deficiencies in mechanistic understanding hinders wider applicability. To clarify its physiological effects, we acquired fMRI whilst simultaneously acquiring TDCS to the right inferior frontal gyrus (rIFG) of healthy human participants, a region involved in coordinating activity within brain networks. TDCS caused widespread modulation of network activity depending on brain state ('rest' or choice reaction time task) and polarity (anodal or cathodal). During task, TDCS increased salience network activation and default mode network deactivation, but had the opposite effect during 'rest'. Furthermore, there was an interaction between brain state and TDCS polarity, with cathodal effects more pronounced during task performance and anodal effects more pronounced during 'rest'. Overall, we show that rIFG TDCS produces brain state and polarity dependent effects within large-scale cognitive networks, in a manner that goes beyond predictions from the current literature.

JOURNAL ARTICLE

Sliwinska MW, Violante IR, Wise RJS, Leech R, Devlin JT, Geranmayeh F, Hampshire Aet al., 2017, Stimulating Multiple-Demand Cortex Enhances Vocabulary Learning, JOURNAL OF NEUROSCIENCE, Vol: 37, Pages: 7606-7618, ISSN: 0270-6474

JOURNAL ARTICLE

Lorenz R, Simmons L, Monti R, Arthur J, Limal S, Laakso I, Leech R, Violante Iet al., 2017, Assessing tACS-induced phosphene perception using closed-loop Bayesian optimization

Transcranial alternating current stimulation (tACS) can evoke illusory flash-like visual percepts known as phosphenes . The perception of phosphenes represents a major experimental challenge when studying tACS-induced effects on cognitive performance. Besides growing concerns that retinal phosphenes themselves could potentially have neuromodulatory effects, the perception of phosphenes may also modify the alertness of participants. Past research has shown that stimulation intensity, frequency and electrode montage affect phosphene perception. However, to date, the effect of an additional tACS parameter on phosphene perception has been completely overlooked: the relative phase difference between stimulation electrodes. This is a crucial and timely topic given the confounding nature of phosphene perception and the increasing number of studies reporting changes in cognitive function following tACS phase manipulations. However, studying phosphene perception for different frequencies and phases simultaneously is not tractable using standard approaches, as the physiologically plausible range of parameters results in a combinatorial explosion of experimental conditions, yielding impracticable experiment durations. To overcome this limitation, here we applied a Bayesian optimization approach to efficiently sample an exhaustive tACS parameter space. Moreover, unlike conventional methodology, which involves subjects judging the perceived phosphene intensity on a rating scale, our study leveraged the strength of human perception by having the optimization driven based on a subject's relative judgement. Applying Bayesian optimization for two different montages, we found that phosphene perception was affected by differences in the relative phase between cortical electrodes. The results were replicated in a second study involving new participants and validated using computational modelling. In summary, our results have important implications for the experimental design and concl

JOURNAL ARTICLE

Lorenz R, Violante I, Monti RP, Montana G, Hampshire A, Leech Ret al., 2017, Dissociating frontoparietal brain networks with neuroadaptive Bayesian optimization

Understanding the unique contributions of frontoparietal networks (FPN) in cognition is challenging because different FPNs spatially overlap and are co-activated for diverse tasks. In order to characterize these networks involves studying how they activate across many different cognitive tasks, which has only previously been possible with meta-analyses. Here, building upon meta-analyses as a starting point, we use neuroadaptive Bayesian optimization, an approach combining real-time analysis of functional neuroimaging data with machine-learning, to discover cognitive tasks that dissociate ventral and dorsal FPN activity from a large pool of tasks. We identify and subsequently refine two cognitive tasks (Deductive Reasoning and Tower of London) that are optimal for dissociating the FPNs. The identified cognitive tasks are not those predicted by meta-analysis, highlighting a different mapping between cognitive tasks and frontoparietal networks than expected. The optimization approach converged on a similar neural dissociation independently for the two different tasks, suggesting a possible common underlying functional mechanism and the need for neurally-derived cognitive taxonomies.

JOURNAL ARTICLE

Violante IR, Li LM, Carmichael DW, Lorenz R, Leech R, Hampshire A, Rothwell JC, Sharp DJet al., 2017, Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance, ELIFE, Vol: 6, ISSN: 2050-084X

JOURNAL ARTICLE

Violante IR, Li LM, Carmichael DW, Lorenz R, Leech R, Hampshire A, Rothwell JC, Sharp DJet al., 2017, Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance., Elife, Vol: 6

Cognitive functions such as working memory (WM) are emergent properties of large-scale network interactions. Synchronisation of oscillatory activity might contribute to WM by enabling the coordination of long-range processes. However, causal evidence for the way oscillatory activity shapes network dynamics and behavior in humans is limited. Here we applied transcranial alternating current stimulation (tACS) to exogenously modulate oscillatory activity in a right frontoparietal network that supports WM. Externally induced synchronization improved performance when cognitive demands were high. Simultaneously collected fMRI data reveals tACS effects dependent on the relative phase of the stimulation and the internal cognitive processing state. Specifically, synchronous tACS during the verbal WM task increased parietal activity, which correlated with behavioral performance. Furthermore, functional connectivity results indicate that the relative phase of frontoparietal stimulation influences information flow within the WM network. Overall, our findings demonstrate a link between behavioral performance in a demanding WM task and large-scale brain synchronization.

JOURNAL ARTICLE

Violante IR, Patricio M, Bernardino I, Rebola J, Abrunhosa AJ, Ferreira N, Castelo-Branco Met al., 2016, GABA deficiency in NF1: A multimodal [11C]-flumazenil and spectroscopy study., Neurology, Vol: 87, Pages: 897-904

OBJECTIVE: To provide a comprehensive investigation of the γ-aminobutyric acid (GABA) system in patients with neurofibromatosis type 1 (NF1) that allows understanding the nature of the GABA imbalance in humans at pre- and postsynaptic levels. METHODS: In this cross-sectional study, we employed multimodal imaging and spectroscopy measures to investigate GABA type A (GABAA) receptor binding, using [(11)C]-flumazenil PET, and GABA concentration, using magnetic resonance spectroscopy (MRS). Fourteen adult patients with NF1 and 13 matched controls were included in the study. MRS was performed in the occipital cortex and in a frontal region centered in the functionally localized frontal eye fields. PET and MRS acquisitions were performed in the same day. RESULTS: Patients with NF1 have reduced concentration of GABA+ in the occipital cortex (p = 0.004) and frontal eye fields (p = 0.026). PET results showed decreased binding of GABAA receptors in patients in the parieto-occipital cortex, midbrain, and thalamus, which are not explained by decreased gray matter levels. CONCLUSIONS: Abnormalities in the GABA system in NF1 involve both GABA concentration and GABAA receptor density suggestive of neurodevelopmental synaptopathy with both pre- and postsynaptic involvement.

JOURNAL ARTICLE

Ribeiro Violante I, Patricio M, Bernardino I, Rebola J, Abrunhosa AJ, Ferreira N, Castelo-Branco Met al., 2016, GABA deficiency in NF1: a multimodal [11C]-Flumazenil and spectroscopy study, Neurology, ISSN: 0028-3878

Objective: To provide a comprehensive investigation of the GABA system inpatients with Neurofibromatosis type 1 (NF1) that allows understanding thenature of the GABA imbalance in humans at pre- and post-synaptic levels.Methods: In this cross-sectional study, we employed multimodal imaging andspectroscopy measures to investigate GABAA receptor binding, using [11C]-Flumazenil positron emission tomography (PET), and GABA concentration,using magnetic resonance spectroscopy (MRS). 14 adult patients with NF1 and13 matched controls were included in the study. MRS was performed in theoccipital cortex and in a frontal region centered in the functionally localizedfrontal-eye fields. PET and MRS acquisitions were performed in the same day.Results: Patients with NF1 have reduced concentration of GABA+ in theoccipital cortex (P = 0.004) and frontal-eye fields (P = 0.026). PET resultsshowed decreased binding of GABAA receptors in patients in the parietooccipitalcortex, midbrain and thalamus, which are not explained by decreasedgrey matter levels.Conclusions: Abnormalities in the GABA system in NF1 involve both GABAconcentration and GABAA receptor density suggestive of neurodevelopmentalsynaptopathy with both pre- and post-synaptic involvement.

JOURNAL ARTICLE

Lorenz R, Monti RP, Violante IR, Anagnostopoulos C, Faisal AA, Montana G, Leech Ret al., 2016, The Automatic Neuroscientist: A framework for optimizing experimental design with closed-loop real-time fMRI, NEUROIMAGE, Vol: 129, Pages: 320-334, ISSN: 1053-8119

JOURNAL ARTICLE

Silva G, Ribeiro MJ, Costa GN, Violante I, Ramos F, Saraiva J, Castelo-Branco Met al., 2016, Peripheral Attentional Targets under Covert Attention Lead to Paradoxically Enhanced Alpha Desynchronization in Neurofibromatosis Type 1, PLOS ONE, Vol: 11, ISSN: 1932-6203

JOURNAL ARTICLE

Lorenz R, Monti RP, Hampshire A, Koush Y, Anagnostopoulos C, Faisal AA, Sharp D, Montana G, Leech R, Violante IRet al., 2016, Towards tailoring non-invasive brain stimulation using real-time fMRI and Bayesian optimization, 6th International Workshop on Pattern Recognition in Neuroimaging (PRNI), Publisher: IEEE, Pages: 49-52, ISSN: 2330-9989

CONFERENCE PAPER

Ribeiro MJ, Violante IR, Bernardino I, Edden RAB, Castelo-Branco Met al., 2015, Abnormal relationship between GABA, neurophysiology and impulsive behavior in neurofibromatosis type 1, CORTEX, Vol: 64, Pages: 194-208, ISSN: 0010-9452

JOURNAL ARTICLE

Majewska P, Ribeiro Violante I, Lorenz R, De Simoni S, Sharp Det al., 2015, EEG characteristics of memory deficits in acute traumatic brain injury patients with post-traumatic amnesia, The Society of British Neurological Surgeons Meeting 2015

CONFERENCE PAPER

Mullins PG, McGonigle DJ, O'Gorman RL, Puts NAJ, Vidyasagar R, Evans CJ, Edden RAEet al., 2014, Current practice in the use of MEGA-PRESS spectroscopy for the detection of GABA, NEUROIMAGE, Vol: 86, Pages: 43-52, ISSN: 1053-8119

JOURNAL ARTICLE

Duarte JV, Ribeiro MJ, Violante IR, Cunha G, Silva E, Castelo-Branco Met al., 2014, Multivariate Pattern Analysis Reveals Subtle Brain Anomalies Relevant to the Cognitive Phenotype in Neurofibromatosis Type 1, HUMAN BRAIN MAPPING, Vol: 35, Pages: 89-106, ISSN: 1065-9471

JOURNAL ARTICLE

Lorenz R, Faisal AA, Dinov M, Ribeiro Violante I, Leech Ret al., 2014, Neurofeedback training of large-scale brain networks, Annual Meeting of Society of Neuroscience

CONFERENCE PAPER

Violante IR, Ribeiro MJ, Edden RAE, Guimarares P, Bernardino I, Rebola J, Cunha G, Silva E, Castelo-Branco Met al., 2013, GABA deficit in the visual cortex of patients with neurofibromatosis type 1: genotype-phenotype correlations and functional impact, BRAIN, Vol: 136, Pages: 918-925, ISSN: 0006-8950

JOURNAL ARTICLE

Violante IR, Ribeiro MJ, Silva ED, Castelo-Branco Met al., 2013, Gyrification, cortical and subcortical morphometry in neurofibromatosis type 1: an uneven profile of developmental abnormalities, JOURNAL OF NEURODEVELOPMENTAL DISORDERS, Vol: 5, ISSN: 1866-1947

JOURNAL ARTICLE

Violante IR, Ribeiro MJ, Cunha G, Bernardino I, Duarte JV, Ramos F, Saraiva J, Silva E, Castelo-Branco Met al., 2012, Abnormal Brain Activation in Neurofibromatosis Type 1: A Link between Visual Processing and the Default Mode Network, PLOS ONE, Vol: 7, ISSN: 1932-6203

JOURNAL ARTICLE

Ribeiro MJ, Violante IR, Bernardino I, Ramos F, Saraiva J, Reviriego P, Upadhyaya M, Silva ED, Castelo-Branco Met al., 2012, Abnormal Achromatic and Chromatic Contrast Sensitivity in Neurofibromatosis Type 1, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, Vol: 53, Pages: 287-293, ISSN: 0146-0404

JOURNAL ARTICLE

Delgado TC, Violante IR, Nieto-Charques L, Cerdan Set al., 2011, Neuroglial metabolic compartmentation underlying leptin deficiency in the obese ob/ob mice as detected by magnetic resonance imaging and spectroscopy methods, JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM, Vol: 31, Pages: 2257-2266, ISSN: 0271-678X

JOURNAL ARTICLE

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