Imperial College London

DrInesRibeiro Violante

Faculty of MedicineDepartment of Brain Sciences

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

63 results found

Violante IR, Alania K, Cassarà AM, Neufeld E, Acerbo E, Carron R, Williamson A, Kurtin DL, Rhodes E, Hampshire A, Kuster N, Boyden ES, Pascual-Leone A, Grossman Net al., 2023, Publisher Correction: Non-invasive temporal interference electrical stimulation of the human hippocampus, Nature Neuroscience, Vol: 26, Pages: 2252-2252, ISSN: 1097-6256

Journal article

Wessel MJ, Beanato E, Popa T, Windel F, Vassiliadis P, Menoud P, Beliaeva V, Violante IR, Abderrahmane H, Dzialecka P, Park C-H, Maceira-Elvira P, Morishita T, Cassara AM, Steiner M, Grossman N, Neufeld E, Hummel FCet al., 2023, Noninvasive theta-burst stimulation of the human striatum enhances striatal activity and motor skill learning, Nature Neuroscience, Vol: 26, Pages: 2005-2016, ISSN: 1097-6256

The stimulation of deep brain structures has thus far only been possible with invasive methods. Transcranial electrical temporal interference stimulation (tTIS) is a novel, noninvasive technology that might overcome this limitation. The initial proof-of-concept was obtained through modeling, physics experiments and rodent models. Here we show successful noninvasive neuromodulation of the striatum via tTIS in humans using computational modeling, functional magnetic resonance imaging studies and behavioral evaluations. Theta-burst patterned striatal tTIS increased activity in the striatum and associated motor network. Furthermore, striatal tTIS enhanced motor performance, especially in healthy older participants as they have lower natural learning skills than younger subjects. These findings place tTIS as an exciting new method to target deep brain structures in humans noninvasively, thus enhancing our understanding of their functional role. Moreover, our results lay the groundwork for innovative, noninvasive treatment strategies for brain disorders in which deep striatal structures play key pathophysiological roles.

Journal article

Violante IR, Alania K, Cassarà AM, Neufeld E, Acerbo E, Carron R, Williamson A, Kurtin DL, Rhodes E, Hampshire A, Kuster N, Boyden ES, Pascual-Leone A, Grossman Net al., 2023, Non-invasive temporal interference electrical stimulation of the human hippocampus., Nat Neurosci, Vol: 26, Pages: 1994-2004

Deep brain stimulation (DBS) via implanted electrodes is used worldwide to treat patients with severe neurological and psychiatric disorders. However, its invasiveness precludes widespread clinical use and deployment in research. Temporal interference (TI) is a strategy for non-invasive steerable DBS using multiple kHz-range electric fields with a difference frequency within the range of neural activity. Here we report the validation of the non-invasive DBS concept in humans. We used electric field modeling and measurements in a human cadaver to verify that the locus of the transcranial TI stimulation can be steerably focused in the hippocampus with minimal exposure to the overlying cortex. We then used functional magnetic resonance imaging and behavioral experiments to show that TI stimulation can focally modulate hippocampal activity and enhance the accuracy of episodic memories in healthy humans. Our results demonstrate targeted, non-invasive electrical stimulation of deep structures in the human brain.

Journal article

Kurtin DL, Arana-Oiarbide G, Lorenz R, Violante IR, Hampshire Aet al., 2023, Planning ahead: Predictable switching recruits task-active and resting-state networks, HUMAN BRAIN MAPPING, Vol: 44, Pages: 5030-5046, ISSN: 1065-9471

Journal article

Soleimani G, Nitsche MA, Bergmann TO, Towhidkhah F, Violante IR, Lorenz R, Kuplicki R, Tsuchiyagaito A, Mulyana B, Mayeli A, Ghobadi-Azbari P, Mosayebi-Samani M, Zilverstand A, Paulus MP, Bikson M, Ekhtiari Het al., 2023, Closing the loop between brain and electrical stimulation: towards precision neuromodulation treatments., Transl Psychiatry, Vol: 13

One of the most critical challenges in using noninvasive brain stimulation (NIBS) techniques for the treatment of psychiatric and neurologic disorders is inter- and intra-individual variability in response to NIBS. Response variations in previous findings suggest that the one-size-fits-all approach does not seem the most appropriate option for enhancing stimulation outcomes. While there is a growing body of evidence for the feasibility and effectiveness of individualized NIBS approaches, the optimal way to achieve this is yet to be determined. Transcranial electrical stimulation (tES) is one of the NIBS techniques showing promising results in modulating treatment outcomes in several psychiatric and neurologic disorders, but it faces the same challenge for individual optimization. With new computational and methodological advances, tES can be integrated with real-time functional magnetic resonance imaging (rtfMRI) to establish closed-loop tES-fMRI for individually optimized neuromodulation. Closed-loop tES-fMRI systems aim to optimize stimulation parameters based on minimizing differences between the model of the current brain state and the desired value to maximize the expected clinical outcome. The methodological space to optimize closed-loop tES fMRI for clinical applications includes (1) stimulation vs. data acquisition timing, (2) fMRI context (task-based or resting-state), (3) inherent brain oscillations, (4) dose-response function, (5) brain target trait and state and (6) optimization algorithm. Closed-loop tES-fMRI technology has several advantages over non-individualized or open-loop systems to reshape the future of neuromodulation with objective optimization in a clinically relevant context such as drug cue reactivity for substance use disorder considering both inter and intra-individual variations. Using multi-level brain and behavior measures as input and desired outcomes to individualize stimulation parameters provides a framework for designing personali

Journal article

Kurtin DL, Giunchiglia V, Vohryzek J, Cabral J, Skeldon AC, Violante IRet al., 2023, Moving from phenomenological to predictive modelling: Progress and pitfalls of modelling brain stimulation in-silico, NeuroImage, Vol: 272, ISSN: 1053-8119

Brain stimulation is an increasingly popular neuromodulatory tool used in both clinical and research settings; however, the effects of brain stimulation, particularly those of non-invasive stimulation, are variable. This variability can be partially explained by an incomplete mechanistic understanding, coupled with a combinatorial explosion of possible stimulation parameters. Computational models constitute a useful tool to explore the vast sea of stimulation parameters and characterise their effects on brain activity. Yet the utility of modelling stimulation in-silico relies on its biophysical relevance, which needs to account for the dynamics of large and diverse neural populations and how underlying networks shape those collective dynamics. The large number of parameters to consider when constructing a model is no less than those needed to consider when planning empirical studies. This piece is centred on the application of phenomenological and biophysical models in non-invasive brain stimulation. We first introduce common forms of brain stimulation and computational models, and provide typical construction choices made when building phenomenological and biophysical models. Through the lens of four case studies, we provide an account of the questions these models can address, commonalities, and limitations across studies. We conclude by proposing future directions to fully realise the potential of computational models of brain stimulation for the design of personalized, efficient, and effective stimulation strategies.

Journal article

Kurtin DL, Scott G, Hebron H, Skeldon AC, Violante IRet al., 2023, Task-based differences in brain state dynamics and their relation to cognitive ability, NeuroImage, Vol: 271, ISSN: 1053-8119

Transient patterns of interregional connectivity form and dissipate in response to varying cognitive demands. Yet, it is not clear how different cognitive demands influence brain state dynamics, and whether these dynamics relate to general cognitive ability. Here, using functional magnetic resonance imaging (fMRI) data, we characterised shared, recurrent, global brain states in 187 participants across the working memory, emotion, language, and relation tasks from the Human Connectome Project. Brain states were determined using Leading Eigenvector Dynamics Analysis (LEiDA). In addition to the LEiDA-based metrics of brain state lifetimes and probabilities, we also computed information-theoretic measures of Block Decomposition Method of complexity, Lempel-Ziv complexity and transition entropy. Information theoretic metrics are notable in their ability to compute relationships amongst sequences of states over time, compared to lifetime and probability, which capture the behaviour of each state in isolation. We then related task-based brain state metrics to fluid intelligence. We observed that brain states exhibited stable topology across a range of numbers of clusters (K = 2:15). Most metrics of brain state dynamics, including state lifetime, probability, and all information theoretic metrics, reliably differed between tasks. However, relationships between state dynamic metrics and cognitive abilities varied according to the task, the metric, and the value of K, indicating that there are contextual relationships between task-dependant state dynamics and trait cognitive ability. This study provides evidence that the brain reconfigures across time in response to cognitive demands, and that there are contextual, rather than generalisable, relationships amongst task, state dynamics, and cognitive ability.

Journal article

Alania K, Rhodes E, Suhayl IB, Violante I, Grossman Net al., 2023, Investigating the direct effect of temporal interference (TI) stimulation on cortical activity with simultaneous EEG recording in humans, Brain Stimulation, Vol: 16, Pages: 343-343, ISSN: 1935-861X

Journal article

Violante I, Alania K, Cassarà A, Neufeld E, Acerbo E, Williamson A, Kurtin D, Rhodes E, Hampshire A, Kuster N, Boyden E, Pascual-Leone A, Grossman Net al., 2023, Non-invasive temporal interference electrical stimulation of the human hippocampus, Brain Stimulation, Vol: 16, Pages: 408-408, ISSN: 1935-861X

Journal article

Hebron H, Lugli B, Dimitrova R, Jaramillo V, Rhodes E, Grossman N, Dijk D-J, Violante IRet al., 2022, Alpha closed-loop auditory stimulation modulates waking alpha oscillations and sleep onset dynamics in a phase-dependent manner in humans

<jats:title>Abstract</jats:title><jats:p>Alpha oscillations play a vital role in managing the brain’s resources, inhibiting neural activity as a function of their phase and amplitude, and are changed in many brain disorders. Developing minimally invasive tools to modulate alpha activity and identifying the parameters that determine its response to exogenous modulators, is essential for the implementation of focussed interventions. We introduce Alpha Closed-Loop Auditory Stimulation (<jats:italic>αCLAS</jats:italic>) as an EEG-based method to augment and investigate these brain rhythms in humans with specificity and selectivity, using targeted auditory stimulation. Across three independent studies, we demonstrate that<jats:italic>αCLAS</jats:italic>alters alpha power, frequency, and connectivity in a phase, amplitude and topography-dependent manner. Using a single-pulse-<jats:italic>αCLAS</jats:italic>evoked potentials approach we show that the effects of auditory stimuli on alpha oscillations and resulting evoked potentials can be explained within the theoretical framework of oscillator theory and a phase-reset mechanism. Finally, we demonstrate the functional relevance of our approach by showing that<jats:italic>αCLAS</jats:italic>modulates sleep onset dynamics in an alpha phase-dependent manner.</jats:p>

Journal article

Brunoni AR, Ekhtiari H, Antal A, Auvichayapat P, Baeken C, Benseñor IM, Bikson M, Boggio P, Borroni B, Brighina F, Brunelin J, Carvalho S, Caumo W, Ciechanski P, Charvet L, Clark VP, Cohen Kadosh R, Cotelli M, Datta A, Deng Z-D, De Raedt R, De Ridder D, Fitzgerald PB, Floel A, Frohlich F, George MS, Ghobadi-Azbari P, Goerigk S, Hamilton RH, Jaberzadeh SJ, Hoy K, Kidgell DJ, Zonoozi AK, Kirton A, Laureys S, Lavidor M, Lee K, Leite J, Lisanby SH, Loo C, Martin DM, Miniussi C, Mondino M, Monte-Silva K, Morales-Quezada L, Nitsche MA, Okano AH, Oliveira CS, Onarheim B, Pacheco-Barrios K, Padberg F, Nakamura-Palacios EM, Palm U, Paulus W, Plewnia C, Priori A, Rajji TK, Razza LB, Rehn EM, Ruffini G, Schellhorn K, Zare-Bidoky M, Simis M, Skorupinski P, Suen P, Thibaut A, Valiengo LCL, Vanderhasselt M-A, Vanneste S, Venkatasubramanian G, Violante IR, Wexler A, Woods AJ, Fregni Fet al., 2022, Digitalized transcranial electrical stimulation: A consensus statement., Clin Neurophysiol, Vol: 143, Pages: 154-165

OBJECTIVE: Although relatively costly and non-scalable, non-invasive neuromodulation interventions are treatment alternatives for neuropsychiatric disorders. The recent developments of highly-deployable transcranial electric stimulation (tES) systems, combined with mobile-Health technologies, could be incorporated in digital trials to overcome methodological barriers and increase equity of access. The study aims are to discuss the implementation of tES digital trials by performing a systematic scoping review and strategic process mapping, evaluate methodological aspects of tES digital trial designs, and provide Delphi-based recommendations for implementing digital trials using tES. METHODS: We convened 61 highly-productive specialists and contacted 8 tES companies to assess 71 issues related to tES digitalization readiness, and processes, barriers, advantages, and opportunities for implementing tES digital trials. Delphi-based recommendations (>60% agreement) were provided. RESULTS: The main strengths/opportunities of tES were: (i) non-pharmacological nature (92% of agreement), safety of these techniques (80%), affordability (88%), and potential scalability (78%). As for weaknesses/threats, we listed insufficient supervision (76%) and unclear regulatory status (69%). Many issues related to methodological biases did not reach consensus. Device appraisal showed moderate digitalization readiness, with high safety and potential for trial implementation, but low connectivity. CONCLUSIONS: Panelists recognized the potential of tES for scalability, generalizability, and leverage of digital trials processes; with no consensus about aspects regarding methodological biases. SIGNIFICANCE: We further propose and discuss a conceptual framework for exploiting shared aspects between mobile-Health tES technologies with digital trials methodology to drive future efforts for digitizing tES trials.

Journal article

Giustiniani A, Vallesi A, Oliveri M, Tarantino V, Ambrosini E, Bortoletto M, Masina F, Busan P, Siebner HR, Fadiga L, Koch G, Leocani L, Lefaucheur JP, Rotenberg A, Zangen A, Violante IR, Moliadze V, Gamboa OL, Ugawa Y, Pascual-Leone A, Ziemann U, Miniussi C, Burgio Fet al., 2022, A questionnaire to collect unintended effects of transcranial magnetic stimulation: A consensus based approach., Clin Neurophysiol, Vol: 141, Pages: 101-108

Transcranial magnetic stimulation (TMS) has been widely used in both clinical and research practice. However, TMS might induce unintended sensations and undesired effects as well as serious adverse effects. To date, no shared forms are available to report such unintended effects. This study aimed at developing a questionnaire enabling reporting of TMS unintended effects. A Delphi procedure was applied which allowed consensus among TMS experts. A steering committee nominated a number of experts to be involved in the Delphi procedure. Three rounds were conducted before reaching a consensus. Afterwards, the questionnaire was publicized on the International Federation of Clinical Neurophysiology website to collect further suggestions by the wider scientific community. A last Delphi round was then conducted to obtain consensus on the suggestions collected during the publicization and integrate them in the questionnaire. The procedure resulted in a questionnaire, that is the TMSens_Q, applicable in clinical and research settings. Routine use of the structured TMS questionnaire and standard reporting of unintended TMS effects will help to monitor the safety of TMS, particularly when applying new protocols. It will also improve the quality of data collection as well as the interpretation of experimental findings.

Journal article

Soleimani G, Nitsche MA, Bergmann TO, Towhidkhah F, Violante I, Lorenz R, Kuplicki R, Tsuchiyagaito A, Mulyana B, Mayeli A, Ghobadi-Azbari P, Samani MM, Zilverstand A, Paulus MP, Bikson M, Ekhtiari Het al., 2022, Closing the loop between brain and electrical stimulation: Towards precision neuromodulation treatments

<p>One of the most critical challenges in using non-invasive brain stimulation (NIBS) techniques for the treatment of psychiatric and neurologic disorders is inter- and intra-individual variability in response to NIBS. Response variations in previous findings suggest that the one-size-fits-all approach does not seem the most appropriate option for enhancing stimulation outcomes. The optimal way to target and apply NIBS in an individual way is yet to be determined while there is a growing body of evidence for its feasibility and effectiveness. Transcranial electrical stimulation (tES) as one of the NIBS techniques has shown promising results in modulating treatment outcomes in several psychiatric and neurologic disorders while faces the same challenge for individual optimization. With the new computational and methodological advances, tES can be integrated with real-time functional magnetic resonance imaging (rtfMRI) to make closed-loop tES-fMRI for individually optimized neuromodulation. The closed-loop tES-fMRI systems can optimize stimulation parameters based on minimizing differences between the model of the current brain state and the desired value to maximize the expected clinical outcome. The methodological space to optimize closed-loop tES fMRI for clinical applications includes (1) stimulation vs. data acquisition timing, (2) fMRI context (task-based or resting-state), (3) inherent brain oscillations, (4) dose-response function, (5) brain target trait and state and (6) optimization algorithm. Closed-loop tES fMRI technology has several advantages over non-individualized or open-loop systems to reshape the future of neuromodulation with objective optimization in a clinically relevant context such as drug cue reactivity for substance use disorder considering both inter and intra-individual variations. Using multi-level brain and behavior measures as input and desired outcomes to individualize stimulation parameters provides a framework for designing pers

Journal article

Ekhtiari H, Ghobadi-Azbari P, Thielscher A, Antal A, Li LM, Shereen AD, Cabral-Calderin Y, Keeser D, Bergmann TO, Jamil A, Violante IR, Almeida J, Meinzer M, Siebner HR, Woods AJ, Stagg CJ, Abend R, Antonenko D, Auer T, Bachinger M, Baeken C, Barron HC, Chase HW, Crinion J, Datta A, Davis MH, Ebrahimi M, Esmaeilpour Z, Falcone B, Fiori V, Ghodratitoostani I, Gilam G, Grabner RH, Greenspan JD, Groen G, Hartwigsen G, Hauser TU, Herrmann CS, Juan C-H, Krekelberg B, Lefebvre S, Liew S-L, Madsen KH, Mahdavifar-Khayati R, Malmir N, Marangolo P, Martin AK, Meeker TJ, Ardabili HM, Moisa M, Momi D, Mulyana B, Opitz A, Orlov N, Ragert P, Ruff CC, Ruffini G, Ruttorf M, Sangchooli A, Schellhorn K, Schlaug G, Sehm B, Soleimani G, Tavakoli H, Thompson B, Timmann D, Tsuchiyagaito A, Ulrich M, Vosskuhl J, Weinrich CA, Zare-Bidoky M, Zhang X, Zoefel B, Nitsche MA, Bikson Met al., 2022, A checklist for assessing the methodological quality of concurrent tES-fMRI studies (ContES checklist): a consensus study and statement, NATURE PROTOCOLS, Vol: 17, Pages: 596-+, ISSN: 1754-2189

Journal article

Bernardino I, Dionísio A, Violante IR, Monteiro R, Castelo-Branco Met al., 2022, Motor Cortex Excitation/Inhibition Imbalance in Young Adults With Autism Spectrum Disorder: A MRS-TMS Approach., Front Psychiatry, Vol: 13, ISSN: 1664-0640

Excitatory/inhibitory imbalance has been suggested as a neurobiological substrate of the cognitive symptomatology in Autism Spectrum Disorder (ASD). Studies using magnetic resonance spectroscopy (MRS) attempted to characterize GABA and Glutamate brain levels in ASD. However mixed findings have been reported. Here, we characterize both neurochemical and physiological aspects of GABA system in ASD by implementing a more comprehensive approach combining MRS and transcranial magnetic stimulation (TMS). A group of 16 young ASD adults and a group of 17 controls participated in this study. We employed one MRS session to assess motor cortex GABA+ and Glutamate+Glutamine (Glx) levels using MEGAPRESS and PRESS sequences, respectively. Additionally, a TMS experiment was implemented including paired-pulse (SICI, ICF and LICI), input-output curve and cortical silent period to probe cortical excitability. Our results showed a significantly increased Glx, with unchanged GABA+ levels in the ASD group compared with controls. Single TMS measures did not differ between groups, although exploratory within-group analysis showed impaired inhibition in SICI5ms, in ASD. Importantly, we observed a correlation between GABA levels and measures of the input-output TMS recruitment curve (slope and MEP amplitude) in the control group but not in ASD, as further demonstrated by direct between group comparisons. In this exploratory study, we found evidence of increased Glx levels which may contribute to ASD excitatory/inhibitory imbalance while highlighting the relevance of conducting further larger-scale studies to investigate the GABA system from complementary perspectives, using both MRS and TMS techniques.

Journal article

Parkin B, Daws R, Das Neves I, Violante I, Soreq E, Faisal A, Sandrone S, Lao-Kaim N, Martin-Bastida A, Roussakis A-A, Piccini P, Hampshire Aet al., 2021, Dissociable effects of age and Parkinson's disease on instruction based learning, Brain Communications, Vol: 3, ISSN: 2632-1297

The cognitive deficits associated with Parkinson’s disease vary across individuals and change across time, with implications for prognosis and treatment. Key outstanding challenges are to define the distinct behavioural characteristics of this disorder and develop diagnostic paradigms that can assess these sensitively in individuals. In a previous study, we measured different aspects of attentional control in Parkinson’s disease using an established fMRI switching paradigm. We observed no deficits for the aspects of attention the task was designed to examine; instead those with Parkinson’s disease learnt the operational requirements of the task more slowly. We hypothesized that a subset of people with early-to-mid stage Parkinson’s might be impaired when encoding rules for performing new tasks. Here, we directly test this hypothesis and investigate whether deficits in instruction-based learning represent a characteristic of Parkinson’s Disease. Seventeen participants with Parkinson’s disease (8 male; mean age: 61.2 years), 18 older adults (8 male; mean age: 61.3 years) and 20 younger adults (10 males; mean age: 26.7 years) undertook a simple instruction-based learning paradigm in the MRI scanner. They sorted sequences of coloured shapes according to binary discrimination rules that were updated at two-minute intervals. Unlike common reinforcement learning tasks, the rules were unambiguous, being explicitly presented; consequently, there was no requirement to monitor feedback or estimate contingencies. Despite its simplicity, a third of the Parkinson’s group, but only one older adult, showed marked increases in errors, 4 SD greater than the worst performing young adult. The pattern of errors was consistent, reflecting a tendency to misbind discrimination rules. The misbinding behaviour was coupled with reduced frontal, parietal and anterior caudate activity when rules were being encoded, but not when attention was initially o

Journal article

Kurtin DL, Violante IR, Zimmerman K, Leech R, Hampshire A, Patel MC, Carmichael DW, Sharp DJ, Li LMet al., 2021, Investigating the interaction between white matter and brain state on tDCS-induced changes in brain network activity, Brain Stimulation, Vol: 14, Pages: 1261-1270, ISSN: 1876-4754

BACKGROUND: Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation whose potential as a cognitive therapy is hindered by our limited understanding of how participant and experimental factors influence its effects. Using functional MRI to study brain networks, we have previously shown in healthy controls that the physiological effects of tDCS are strongly influenced by brain state. We have additionally shown, in both healthy and traumatic brain injury (TBI) populations, that the behavioral effects of tDCS are positively correlated with white matter (WM) structure. OBJECTIVES: In this study we investigate how these two factors, WM structure and brain state, interact to shape the effect of tDCS on brain network activity. METHODS: We applied anodal, cathodal and sham tDCS to the right inferior frontal gyrus (rIFG) of healthy (n = 22) and TBI participants (n = 34). We used the Choice Reaction Task (CRT) performance to manipulate brain state during tDCS. We acquired simultaneous fMRI to assess activity of cognitive brain networks and used Fractional Anisotropy (FA) as a measure of WM structure. RESULTS: We find that the effects of tDCS on brain network activity in TBI participants are highly dependent on brain state, replicating findings from our previous healthy control study in a separate, patient cohort. We then show that WM structure further modulates the brain-state dependent effects of tDCS on brain network activity. These effects are not unidirectional - in the absence of task with anodal and cathodal tDCS, FA is positively correlated with brain activity in several regions of the default mode network. Conversely, with cathodal tDCS during CRT performance, FA is negatively correlated with brain activity in a salience network region. CONCLUSIONS: Our results show that experimental and participant factors interact to have unexpected effects on brain network activity, and that these effects are not fully predictable by studying the fa

Journal article

Mayes W, Gentle J, Parisi I, Dixon L, van Velzen J, Violante Iet al., 2021, Top-down Inhibitory Motor Control Is Preserved in Adults with Developmental Coordination Disorder, DEVELOPMENTAL NEUROPSYCHOLOGY, Vol: 46, Pages: 409-424, ISSN: 8756-5641

Journal article

Soreq E, Violante IR, Daws R, Hampshire Aet al., 2021, Neuroimaging evidence for a network sampling theory of individual differences in human intelligence, Nature Communications, Vol: 12, ISSN: 2041-1723

Despite a century of research, it remains unclear whether human intelligence should be studied as one dominant, several major, or many distinct abilities, and how such abilities relate to the functional organisation of the brain. Here, we combine psychometric and machine learning methods to examine in a data-driven manner how factor structure and individual variability in cognitive-task performance relate to dynamic-network connectomics. We report that 12 sub-tasks from an established intelligence test can be accurately multi-way classified (74%, chance 8.3%) based on the network states that they evoke. The proximities of the tasks in behavioural-psychometric space correlate with the similarities of their network states. Furthermore, the network states were more accurately classified for higher relative to lower performing individuals. These results suggest that the human brain uses a high-dimensional network-sampling mechanism to flexibly code for diverse cognitive tasks. Population variability in intelligence test performance relates to the fidelity of expression of these task-optimised network states.

Journal article

Beppi C, Violante IR, Scott G, Sandrone Set al., 2021, EEG, MEG and neuromodulatory approaches to explore cognition: Current status and future directions, BRAIN AND COGNITION, Vol: 148, ISSN: 0278-2626

Journal article

Cogdell-Brooke LS, Sowden PT, Violante IR, Thompson HEet al., 2020, Ameta-analysisof functional magnetic resonance imaging studies of divergent thinking using activation likelihood estimation, HUMAN BRAIN MAPPING, Vol: 41, Pages: 5057-5077, ISSN: 1065-9471

Journal article

Fagerholm ED, Tangwiriyasakul C, Friston KJ, Violante IR, Williams S, Carmichael DW, Perani S, Turkheimer FE, Moran RJ, Leech R, Richardson MPet al., 2020, Neural diffusivity and pre-emptive epileptic seizure intervention, PLOS COMPUTATIONAL BIOLOGY, Vol: 16, ISSN: 1553-734X

Journal article

Araña-Oiarbide G, Daws RE, Lorenz R, Violante IR, Hampshire Aet al., 2020, Preferential activation of the posterior Default-Mode Network with sequentially predictable task switches

<jats:title>Abstract</jats:title><jats:p>The default-mode network (DMN) has been primarily associated with internally-directed and self-relevant cognition. This perspective is expanding to recognise its importance in executive behaviours like switching. We investigated the effect different task-switching manipulations have on DMN activation in two studies with novel fMRI paradigms. In the first study, the paradigm manipulated visual discriminability, visuo-perceptual distance and sequential predictability during switching. Increased posterior cingulate/precuneus (PCC/PrCC) activity was evident during switching; critically, this was strongest when the occurrence of the switch was predictable. In the second study, we sought to replicate and further investigate this switch-related effect with a fully factorial design manipulating sequential, spatial and visual-feature predictability. Whole-brain analysis again identified a PCC/PrCC-centred cluster that was more active for sequentially predictable versus unpredictable switches, but not for the other predictability dimensions. We propose PCC/PrCC DMN subregions may play a prominent executive role in mapping the sequential structure of complex tasks.</jats:p>

Journal article

Beppi C, Violante IR, Hampshire A, Grossman N, Sandrone Set al., 2020, Patterns of Focal- and Large-Scale Synchronization in Cognitive Control and Inhibition: A Review, FRONTIERS IN HUMAN NEUROSCIENCE, Vol: 14, ISSN: 1662-5161

Journal article

Cogdell-Brooke L, Stampacchia S, Jefferies E, Violante IR, Thompson HEet al., 2020, Consistently inconsistent: Multimodal episodic deficits in semantic aphasia, NEUROPSYCHOLOGIA, Vol: 140, ISSN: 0028-3932

Journal article

Fagerholm ED, Moran RJ, Violante IR, Leech R, Friston KJet al., 2020, Dynamic causal modelling of phase-amplitude interactions, NEUROIMAGE, Vol: 208, ISSN: 1053-8119

Journal article

Goldthorpe RA, Rapley JM, Violante IR, 2020, A Systematic Review of Non-invasive Brain Stimulation Applications to Memory in Healthy Aging., Front Neurol, Vol: 11, ISSN: 1664-2295

It has long been acknowledged that memory changes over the course of one's life, irrespective of diseases like dementia. Approaches to mitigate these changes have however yielded mixed results. Brain stimulation has been identified as one novel approach of augmenting older adult's memory. Thus far, such approaches have however been nuanced, targeting different memory domains with different methodologies. This has produced an amalgam of research with an unclear image overall. This systematic review therefore aims to clarify this landscape, evaluating, and interpreting available research findings in a coherent manner. A systematic search of relevant literature was conducted across Medline, PsycInfo, Psycarticles and the Psychology and Behavioral Sciences Collection, which uncovered 44 studies employing non-invasive electrical brain stimulation in healthy older adults. All studies were of generally good quality spanning numerous memory domains. Within these, evidence was found for non-invasive brain stimulation augmenting working, episodic, associative, semantic, and procedural memory, with the first three domains having the greatest evidence base. Key sites for stimulation included the left dorsolateral prefrontal cortex (DLPFC), temporoparietal region, and primary motor cortex, with transcranial direct current stimulation (tDCS) holding the greatest literature base. Inconsistencies within the literature are highlighted and interpreted, however this discussion was constrained by potential confounding variables within the literature, a risk of bias, and challenges defining research aims and results. Non-invasive brain stimulation often did however have a positive and predictable impact on older adult's memory, and thus warrants further research to better understand these effects.

Journal article

d'Almeida OC, Violante IR, Quendera B, Moreno C, Gomes L, Castelo-Branco Met al., 2020, The neurometabolic profiles of GABA and Glutamate as revealed by proton magnetic resonance spectroscopy in type 1 and type 2 diabetes., PLoS One, Vol: 15

Glucose metabolism is pivotal for energy and neurotransmitter synthesis and homeostasis, particularly in Glutamate and GABA systems. In turn, the stringent control of inhibitory/excitatory tonus is known to be relevant in neuropsychiatric conditions. Glutamatergic neurotransmission dominates excitatory synaptic functions and is involved in plasticity and excitotoxicity. GABAergic neurochemistry underlies inhibition and predicts impaired psychophysical function in diabetes. It has also been associated with cognitive decline in people with diabetes. Still, the relation between metabolic homeostasis and neurotransmission remains elusive. Two 3T proton MR spectroscopy studies were independently conducted in the occipital cortex to provide insight into inhibitory/excitatory homeostasis (GABA/Glutamate) and to evaluate the impact of chronic metabolic control on the levels and regulation (as assessed by regression slopes) of the two main neurotransmitters of the CNS in type 2 diabetes (T2DM) and type 1 diabetes (T1DM). Compared to controls, participants with T2DM showed significantly lower Glutamate, and also GABA. Nevertheless, higher levels of GABA/Glx (Glutamate+Glutamine), and lower levels of Glutamate were associated with poor metabolic control in participants with T2DM. Importantly, the relationship between GABA/Glx and HbA1c found in T2DM supports a relationship between inhibitory/excitatory balance and metabolic control. Interestingly, this neurometabolic profile was undetected in T1DM. In this condition we found strong evidence for alterations in MRS surrogate measures of neuroinflammation (myo-Inositol), positively related to chronic metabolic control. Our results suggest a role for Glutamate as a global marker of T2DM and a sensitive marker of glycemic status. GABA/Glx may provide a signature of cortical metabolic state in poorly controlled patients as assessed by HbA1c levels, which indicate long-term blood Glucose control. These findings are consistent with an

Journal article

Li L, Violante I, Zimmerman K, Leech R, Hampshire A, Patel M, Opitz A, McArthur D, Carmichael D, Sharp DJet al., 2019, Traumatic axonal injury influences the cognitive effect of non-invasive brain stimulation, Brain, Vol: 142, Pages: 3280-3293, ISSN: 1460-2156

Non-invasive brain stimulation has been widely investigated for as a potentialtreatment for a range of neurological and psychiatric conditions, including braininjury. However, the behavioural effects of brain stimulation are very variable, forreasons that are poorly understood. This is a particular challenge for traumatic braininjury, where patterns of damage and their clinical effects are heterogenous. Here wetest the hypothesis that the response to transcranial direct current stimulationfollowing traumatic brain injury is dependent on white matter damage within thestimulated network. We used a novel simultaneous stimulation-MRI protocolapplying anodal, cathodal and sham stimulation to 24 healthy and 35 moderate/severetraumatic brain injury patients. Stimulation was applied to the right inferior frontalgyrus/anterior insula node of the Salience Network, which was targeted because ourprevious work had shown its importance to executive function. Stimulation wasapplied during performance of the Stop Signal Task, which assesses responseinhibition, a key component of executive function. Structural MRI was used to assessthe extent of brain injury, including diffusion MRI assessment of post-traumaticaxonal injury. Functional MRI, which was simultaneously acquired to delivery ofstimulation, assessed the effects of stimulation on cognitive network function. Anodalstimulation improved response inhibition in control participants, an effect that was notobserved in the patient group. The extent of traumatic axonal injury within theSalience Network strongly influenced the behavioural response to stimulation.Increasing damage to the tract connecting the stimulated right inferior frontalgyrus/anterior insula to the rest of the SN was associated with reduced beneficialeffects of stimulation. In addition, anodal stimulation normalised Default ModeNetwork activation in patients with poor response inhibition, suggesting thatstimulation modulates communication between the networks invo

Journal article

Lorenz R, Simmons LE, Monti RP, Arthur JL, Limal S, Laakso I, Leech R, Violante IRet al., 2019, Efficiently searching through large tACS parameter spaces using closed-loop Bayesian optimization, BRAIN STIMULATION, Vol: 12, Pages: 1484-1489, ISSN: 1935-861X

Journal article

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