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Phylactou P, Pham TNM, Narskhani N, Diya N, Seminowicz DA, Schabrun SM. Phosphene and motor transcranial magnetic stimulation thresholds are correlated: A meta-analytic investigation. Prog Neuropsychopharmacol Biol Psychiatry 2024; 133:111020. [PMID: 38692474 DOI: 10.1016/j.pnpbp.2024.111020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/22/2024] [Accepted: 04/28/2024] [Indexed: 05/03/2024]
Abstract
Transcranial magnetic stimulation (TMS) is commonly delivered at an intensity defined by the resting motor threshold (rMT), which is thought to represent cortical excitability, even if the TMS target area falls outside of the motor cortex. This approach rests on the assumption that cortical excitability, as measured through the motor cortex, represents a 'global' measure of excitability. Another common approach to measure cortical excitability relies on the phosphene threshold (PT), measured through the visual cortex of the brain. However, it remains unclear whether either estimate can serve as a singular measure to infer cortical excitability across different brain regions. If PT and rMT can indeed be used to infer cortical excitability across brain regions, they should be correlated. To test this, we systematically identified previous studies that measured PT and rMT to calculate an overall correlation between the two estimates. Our results, based on 16 effect sizes from eight studies, indicated that PT and rMT are correlated (ρ = 0.4), and thus one measure could potentially serve as a measure to infer cortical excitability across brain regions. Three exploratory meta-analyses revealed that the strength of the correlation is affected by different methodologies, and that PT intensities are higher than rMT. Evidence for a PT-rMT correlation remained robust across all analyses. Further research is necessary for an in-depth understanding of how cortical excitability is reflected through TMS.
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Affiliation(s)
- P Phylactou
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada; The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON, Canada.
| | - T N M Pham
- The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON, Canada
| | - N Narskhani
- The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON, Canada
| | - N Diya
- The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON, Canada
| | - D A Seminowicz
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - S M Schabrun
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada; The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON, Canada
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2
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Chen S, Lu H, Cheng C, Ye Z, Hua T. Rapidly repeated visual stimulation induces long-term potentiation of VEPs and increased content of membrane AMPA and NMDA receptors in the V1 cortex of cats. Front Neurosci 2024; 18:1386801. [PMID: 38831757 PMCID: PMC11144871 DOI: 10.3389/fnins.2024.1386801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/25/2024] [Indexed: 06/05/2024] Open
Abstract
Studies report that rapidly repeated sensory stimulation can evoke LTP-like improvement of neural response in the sensory cortex. Whether this neural response potentiation is similar to the classic LTP induced by presynaptic electrical stimulation remains unclear. This study examined the effects of repeated high-frequency (9 Hz) versus low-frequency (1 Hz) visual stimulation on visually-evoked field potentials (VEPs) and the membrane protein content of AMPA / NMDA receptors in the primary visual cortex (V1) of cats. The results showed that repeated high-frequency visual stimulation (HFS) caused a long-term improvement in peak-to-peak amplitude of V1-cortical VEPs in response to visual stimuli at HFS-stimulated orientation (SO: 90°) and non-stimulated orientation (NSO: 180°), but the effect exhibited variations depending on stimulus orientation: the amplitude increase of VEPs in response to visual stimuli at SO was larger, reached a maximum earlier and lasted longer than at NSO. By contrast, repeated low-frequency visual stimulation (LFS) had not significantly affected the amplitude of V1-cortical VEPs in response to visual stimuli at both SO and NSO. Furthermore, the membrane protein content of the key subunit GluA1 of AMPA receptors and main subunit NR1 of AMPA receptors in V1 cortex was significantly increased after HFS but not LFS when compared with that of control cats. Taken together, these results indicate that HFS can induce LTP-like improvement of VEPs and an increase in membrane protein of AMPA and NMDA receptors in the V1 cortex of cats, which is similar to but less specific to stimulus orientation than the classic LTP.
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Affiliation(s)
| | | | | | | | - Tianmiao Hua
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
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3
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Zak N, Moberget T, Bøen E, Boye B, Rygvold TW, Malt UF, Andreassen OA, Andersson S, Westlye LT, Elvsåshagen T. Baseline long-term potentiation-like cortical plasticity is associated with longitudinal cortical thinning in healthy adults and in adults with bipolar disorder type II. Eur J Neurosci 2023; 58:2824-2837. [PMID: 37163975 DOI: 10.1111/ejn.16038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 03/20/2023] [Accepted: 05/06/2023] [Indexed: 05/12/2023]
Abstract
The precise neurobiological processes underlying cerebral cortical thinning in aging and psychiatric illnesses remain undetermined, yet aging- and synaptic dysfunction-related loss of synapses are potentially important mechanisms. We used long-term potentiation-like plasticity of the visual evoked potential as an index of synaptic function in the cortex and hypothesized that plasticity at baseline would be negatively associated with future cortical thinning in healthy adults and in adults with bipolar disorder type II. Thirty-two healthy adults and 15 adults with bipolar disorder type II underwent electroencephalography-based measurement of visual evoked potential plasticity and 3T magnetic resonance imaging of the brain at baseline and a follow-up brain scan on average 2.3 years later. The relationships between visual evoked potential plasticity at baseline and longitudinal cortical thickness changes were examined using Freesurfer and the Permutation Analysis of Linear Models tool. The analyses showed a negative association between the plasticity of the N1 visual evoked potential amplitude at baseline and thinning rate in the medial and lateral parietal and medial occipital cortices in healthy adults and in the right medial occipital cortex in the total sample of healthy adults and adults with bipolar disorder type II, indicating greater thinning over time in subjects with less N1 plasticity (pFWER < .05). Although preliminary, the results indicate an association between visual evoked potential plasticity and the future rate of cortical thinning in healthy adults and in bipolar disorder type II, supporting the hypothesis that cortical thinning might be related to synaptic dysfunction.
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Affiliation(s)
- Nathalia Zak
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Torgeir Moberget
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
| | - Erlend Bøen
- Unit for Psychosomatics and C-L psychiatry for adults, Oslo University Hospital, Oslo, Norway
| | - Birgitte Boye
- Unit for Psychosomatics and C-L psychiatry for adults, Oslo University Hospital, Oslo, Norway
- Department of Behavioral Medicine, University of Oslo, Oslo, Norway
| | | | - Ulrik F Malt
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Research and Education, Oslo University Hospital, Oslo, Norway
| | - Ole A Andreassen
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | | | - Lars T Westlye
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
- Department of Psychology, University of Oslo, Oslo, Norway
| | - Torbjørn Elvsåshagen
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Neurology, Oslo University Hospital, Oslo, Norway
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4
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Dias JW, McClaskey CM, Rumschlag JA, Harris KC. Sensory tetanisation to induce long-term-potentiation-like plasticity: A review and reassessment of the approach. Eur J Neurosci 2022; 56:6115-6140. [PMID: 36227258 PMCID: PMC9772088 DOI: 10.1111/ejn.15847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 09/02/2022] [Accepted: 10/05/2022] [Indexed: 12/29/2022]
Abstract
There is great interest in developing non-invasive approaches for studying cortical plasticity in humans. High-frequency presentation of auditory and visual stimuli, or sensory tetanisation, can induce long-term-potentiation-like (LTP-like) changes in cortical activity. However, contrasting effects across studies suggest that sensory tetanisation may be unreliable. We review these contrasting effects, conduct our own study of auditory and visual tetanisation, and perform meta-analyses to determine the average effect of sensory tetanisation across studies. We measured auditory-evoked amplitude changes in a group of younger (18-29 years of age) and older (55-83 years of age) adults following tetanisation to 1 and 4 kHz tone bursts and following a slow-presentation control. We also measured visual-evoked amplitude changes following tetanisation to horizontal and vertical sign gradients. Auditory and visual response amplitudes decreased following tetanisation, consistent with some studies but contrasting with others finding amplitude increases (i.e. LTP-like changes). Older adults exhibited more modest auditory-evoked amplitude decreases, but visual-evoked amplitude decreases like those of younger adults. Changes in response amplitude were not specific to tetanised stimuli. Importantly, slow presentation of auditory tone bursts produced response amplitude changes approximating those observed following tetanisation in younger adults. Meta-analyses of visual and auditory tetanisation studies found that the overall effect of sensory tetanisation was not significant across studies or study sites. The results suggest that sensory tetanisation may not produce reliable changes in cortical responses and more work is needed to determine the validity of sensory tetanisation as a method for inducing human cortical plasticity in vivo.
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Affiliation(s)
- James W Dias
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Carolyn M McClaskey
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jeffrey A Rumschlag
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Kelly C Harris
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
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Granerud G, Elvsåshagen T, Arntzen E, Juhasz K, Emilsen NM, Sønderby IE, Nærland T, Malt EA. A family study of symbolic learning and synaptic plasticity in autism spectrum disorder. Front Hum Neurosci 2022; 16:950922. [PMID: 36504626 PMCID: PMC9730282 DOI: 10.3389/fnhum.2022.950922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 05/23/2022] [Indexed: 11/25/2022] Open
Abstract
The current study presents a male with autism spectrum disorder (ASD) and a 3q29 deletion, and three healthy first-degree relatives. Our magnetic resonance imaging (MRI) dataset included a healthy control subset. We describe a comprehensive multimodal approach, including equivalence class formation, neurocognitive testing, MRI, and electroencephalography (EEG)-based cortical plasticity, which can provide new insights into socio-communicative and learning impairments and neural underpinnings in ASD. On neurocognitive testing, the proband showed reduced processing speed, attending behavior, and executive function. He required more training trials in equivalence class training compared with family members and exhibited impaired priming of words compared with priming with images. The proband had smaller intracranial volume and surface area and a larger visual evoked potential (VEP) C1 amplitude than family members and intact long-term potentiation (LTP)-like visual cortex plasticity. Together, these results suggest that 3q29 deletion-related ASD is associated with impaired problem-solving strategies in complex socio-communicative and learning tasks, smaller intracranial and surface area, altered VEP amplitude, and normal LTP-like visual cortex plasticity. Further studies are needed to clarify whether this multimodal approach can be used to identify ASD subgroups with distinct neurobiological alterations and to uncover mechanisms underlying socio-communicative and learning impairments. Lay Summary: We studied learning, brain activity, and brain structure in a person with autism and a genetic aberration, and his close relatives. Compared with relatives, the person with autism required more training for learning, and visual learning was better than verbal learning. This person had some changes in the activity of the visual cortex, and the size and the surface area of the brain were reduced. Knowledge about learning and brain mechanisms is valuable for the development of training programs for individuals with autism.
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Affiliation(s)
- Guro Granerud
- Department of Adult Habilitation, Akershus University Hospital, Oslo, Norway,Department of Behavioral Science, Oslo Metropolitan University, Oslo, Norway,KG Jebsen Centre for Neurodevelopmental Disorders, University of Oslo, Oslo, Norway,*Correspondence: Guro Granerud
| | - Torbjørn Elvsåshagen
- Norwegian Centre for Mental Disorders Research, Oslo University Hospital, Oslo, Norway,Department of Neurology, Oslo University Hospital, Oslo, Norway,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Erik Arntzen
- Department of Behavioral Science, Oslo Metropolitan University, Oslo, Norway
| | - Katalin Juhasz
- Department of Adult Habilitation, Akershus University Hospital, Oslo, Norway
| | - Nina Merete Emilsen
- Department of Adult Habilitation, Akershus University Hospital, Oslo, Norway
| | - Ida Elken Sønderby
- KG Jebsen Centre for Neurodevelopmental Disorders, University of Oslo, Oslo, Norway,Norwegian Centre for Mental Disorders Research, Oslo University Hospital, Oslo, Norway,Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Terje Nærland
- KG Jebsen Centre for Neurodevelopmental Disorders, University of Oslo, Oslo, Norway,NevSom Department of Rare Disorders and Disabilities, Oslo University Hospital, Oslo, Norway
| | - Eva Albertsen Malt
- Department of Adult Habilitation, Akershus University Hospital, Oslo, Norway,Institute of Clinical Medicine, Campus Ahus, University of Oslo, Oslo, Norway
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6
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Plasticity of visual evoked potentials in patients with neurofibromatosis type 1. Clin Neurophysiol 2022; 142:220-227. [DOI: 10.1016/j.clinph.2022.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 08/01/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022]
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Guidali G, Roncoroni C, Bolognini N. Paired associative stimulations: Novel tools for interacting with sensory and motor cortical plasticity. Behav Brain Res 2021; 414:113484. [PMID: 34302877 DOI: 10.1016/j.bbr.2021.113484] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 12/26/2022]
Abstract
In the early 2000s, a novel non-invasive brain stimulation protocol, the paired associative stimulation (PAS), was introduced, allowing to induce and investigate Hebbian associative plasticity within the humans' motor system, with patterns resembling spike-timing-dependent plasticity properties found in cellular models. Since this evidence, PAS efficacy has been proved in healthy, and to a lesser extent, in clinical populations. Recently, novel 'modified' protocols targeting sensorimotor and crossmodal networks appeared in the literature. In the present work, we have reviewed recent advances using these 'modified' PAS protocols targeting sensory and motor cortical networks. To better categorize them, we propose a novel classification according to the nature of the peripheral and cortical stimulations (i.e., within-system, cross-systems, and cortico-cortical PAS). For each protocol of the categories mentioned above, we describe and discuss their main features, how they have been used to study and promote brain plasticity, and their advantages and disadvantages. Overall, current evidence suggests that these novel non-invasive brain stimulation protocols represent very promising tools to study the plastic properties of humans' sensorimotor and crossmodal networks, both in the healthy and in the damaged central nervous system.
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Affiliation(s)
- Giacomo Guidali
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy; Department of Psychology & NeuroMI - Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy.
| | - Camilla Roncoroni
- Department of Psychology & NeuroMI - Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Nadia Bolognini
- Department of Psychology & NeuroMI - Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy; Laboratory of Neuropsychology, IRCCS Istituto Auxologico Italiano, Milan, Italy
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8
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Jacob MS, Roach BJ, Hamilton HK, Carrión RE, Belger A, Duncan E, Johannesen J, Keshavan M, Loo S, Niznikiewicz M, Addington J, Bearden CE, Cadenhead KS, Cannon TD, Cornblatt BA, McGlashan TH, Perkins DO, Stone W, Tsuang M, Walker EF, Woods SW, Mathalon DH. Visual cortical plasticity and the risk for psychosis: An interim analysis of the North American Prodrome Longitudinal Study. Schizophr Res 2021; 230:26-37. [PMID: 33667856 PMCID: PMC8328744 DOI: 10.1016/j.schres.2021.01.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 11/08/2020] [Accepted: 01/29/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Adolescence/early adulthood coincides with accelerated pruning of cortical synapses and the onset of schizophrenia. Cortical gray matter reduction and dysconnectivity in schizophrenia are hypothesized to result from impaired synaptic plasticity mechanisms, including long-term potentiation (LTP), since deficient LTP may result in too many weak synapses that are then subject to over-pruning. Deficient plasticity has already been observed in schizophrenia. Here, we assessed whether such deficits are present in the psychosis risk syndrome (PRS), particularly those who subsequently convert to full psychosis. METHODS An interim analysis was performed on a sub-sample from the NAPLS-3 study, including 46 healthy controls (HC) and 246 PRS participants. All participants performed an LTP-like visual cortical plasticity paradigm involving assessment of visual evoked potentials (VEPs) elicited by vertical and horizontal line gratings before and after high frequency ("tetanizing") visual stimulation with one of the gratings to induce "input-specific" neuroplasticity (i.e., VEP changes specific to the tetanized stimulus). Non-parametric, cluster-based permutation testing was used to identify electrodes and timepoints that demonstrated input-specific plasticity effects. RESULTS Input-specific pre-post VEP changes (i.e., increased negative voltage) were found in a single spatio-temporal cluster covering multiple occipital electrodes in a 126-223 ms time window. This plasticity effect was deficient in PRS individuals who subsequently converted to psychosis, relative to PRS non-converters and HC. CONCLUSIONS Input-specific LTP-like visual plasticity can be measured from VEPs in adolescents and young adults. Interim analyses suggest that deficient visual cortical plasticity is evident in those PRS individuals at greatest risk for transition to psychosis.
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Affiliation(s)
- Michael S. Jacob
- VA San Francisco Healthcare System, San Francisco, CA, USA,Department of Psychiatry and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Brian J. Roach
- VA San Francisco Healthcare System, San Francisco, CA, USA
| | - Holly K. Hamilton
- VA San Francisco Healthcare System, San Francisco, CA, USA,Department of Psychiatry and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Ricardo E. Carrión
- Division of Psychiatry Research, The Zucker Hillside Hospital, North Shore-Long Island Jewish Health System, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY, USA,Department of Psychiatry, Hofstra North Shore-LIJ School of Medicine, Hempstead, New York, USA
| | - Aysenil Belger
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Erica Duncan
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA,Atlanta Veterans Affairs Medical Center, Decatur, GA, USA
| | - Jason Johannesen
- Department of Psychiatry, Yale University, School of Medicine, New Haven, CT, USA
| | - Matcheri Keshavan
- Department of Psychiatry, Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Boston, MA, USA
| | - Sandra Loo
- Semel Institute for Neuroscience and Human Behavior, Department of Psychology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Margaret Niznikiewicz
- Department of Psychiatry, Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Boston, MA, USA
| | - Jean Addington
- Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada
| | - Carrie E. Bearden
- Semel Institute for Neuroscience and Human Behavior, Department of Psychology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kristin S. Cadenhead
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Tyrone D. Cannon
- Department of Psychiatry, Yale University, School of Medicine, New Haven, CT, USA,Department of Psychology, Yale University, School of Medicine, New Haven, CT, USA
| | - Barbara A. Cornblatt
- Division of Psychiatry Research, The Zucker Hillside Hospital, North Shore-Long Island Jewish Health System, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY, USA,Department of Psychiatry, Hofstra North Shore-LIJ School of Medicine, Hempstead, New York, USA,Department of Molecular Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY, USA
| | - Thomas H. McGlashan
- Department of Psychiatry, Yale University, School of Medicine, New Haven, CT, USA
| | - Diana O. Perkins
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - William Stone
- Department of Psychiatry, Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Boston, MA, USA
| | - Ming Tsuang
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | | | - Scott W. Woods
- Department of Psychiatry, Yale University, School of Medicine, New Haven, CT, USA
| | - Daniel H. Mathalon
- VA San Francisco Healthcare System, San Francisco, CA, USA,Department of Psychiatry and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
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Reduced visual cortical plasticity in autism spectrum disorder. Brain Res Bull 2021; 170:11-21. [PMID: 33545310 DOI: 10.1016/j.brainresbull.2021.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 11/22/2022]
Abstract
There is increasing evidence implicating altered NMDA-receptor function in autism spectrum disorder (ASD). To investigate potential alterations in NMDA-dependent cortical plasticity in ASD, we examined the effect of visual high-frequency stimulation (HFS) on changes in plasticity in the visual cortex, measured by persistent changes in visual evoked potentials (VEPs), in individuals with ASD (n = 16) and neurotypical controls (NT; n = 15). VEPs were elicited by a checkerboard circle (0.83 Hz, 2-min blocks) at baseline and at 2, 4, and 20 min following exposure to HFS (8.87 Hz, 2 min), previously shown to induce LTP-like changes in the visual cortex. Difference waves were created by subtracting VEPs measured at baseline from each Post-HFS measure, and group differences assessed. We found that HFS resulted in reduced short-term potentiation of VEPs in ASD compared to NT participants. Thus, whilst ASD participants showed significant potentiation of the VEP immediately after HFS, this enhancement was not maintained, and only persisted into the second post-HFS assessment block in NT participants. Notably, ASD individuals who self-reported being more sensitive to visual stimuli showed greater shorter-term potentiation following visual HFS. Critically, there were no group differences in degree of neural entrainment to the visual HFS, or in attentional vigilance and task performance. These findings suggests that visual cortical plasticity is atypical in ASD, results consistent with reported altered NMDA receptor function in ASD.
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10
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Transcranial direct current stimulation induces long-term potentiation-like plasticity in the human visual cortex. Transl Psychiatry 2021; 11:17. [PMID: 33414402 PMCID: PMC7791098 DOI: 10.1038/s41398-020-01134-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/27/2020] [Accepted: 12/03/2020] [Indexed: 12/22/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is increasingly used as a form of noninvasive brain stimulation to treat psychiatric disorders; however, its mechanism of action remains unclear. Prolonged visual stimulation (PVS) can enhance evoked EEG potentials (visually evoked potentials, VEPs) and has been proposed as a tool to examine long-term potentiation (LTP) in humans. The objective of the current study was to induce and analyze VEP plasticity and examine whether tDCS could either modulate or mimic plasticity changes induced by PVS. Thirty-eight healthy participants received tDCS, PVS, either treatment combined or neither treatment, with stimulation sessions being separated by one week. One session consisted of a baseline VEP measurement, one stimulation block, and six test VEP measurements. For PVS, a checkerboard reversal pattern was presented, and for tDCS, a constant current of 1 mA was applied via each bioccipital anodal target electrode for 10 min (Fig. S1). Both stimulation types decreased amplitudes of C1 compared to no stimulation (F = 10.1; p = 0.002) and led to a significantly smaller increase (PVS) or even decrease (tDCS) in N1 compared to no stimulation (F = 4.7; p = 0.034). While all stimulation types increased P1 amplitudes, the linear mixed effects model did not detect a significant difference between active stimulation and no stimulation. Combined stimulation induced sustained plastic modulation of C1 and N1 but with a smaller effect size than what would be expected for an additive effect. The results demonstrate that tDCS can directly induce LTP-like plasticity in the human cortex and suggest a mechanism of action of tDCS relying on the restoration of dysregulated synaptic plasticity in psychiatric disorders such as depression and schizophrenia.
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11
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Rygvold TW, Hatlestad-Hall C, Elvsåshagen T, Moberget T, Andersson S. Do visual and auditory stimulus-specific response modulation reflect different mechanisms of neocortical plasticity? Eur J Neurosci 2020; 53:1072-1085. [PMID: 32897598 DOI: 10.1111/ejn.14964] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 07/27/2020] [Accepted: 08/27/2020] [Indexed: 01/27/2023]
Abstract
Stimulus response modulation (SRM) of sensory evoked potentials represents a promising method as a non-invasive index of long-term potentiation (LTP)-like synaptic plasticity in the human sensory cortices. As of today, however, no consensus exists regarding which experimental parameters elicit the most robust SRM response. The aim of the current study was twofold; firstly, we aimed to replicate former studies demonstrating visual SRM in healthy adults. Second, we integrated visual and auditory stimuli within the same SRM recording session to assay potential cross-modal associations. Such an association between modalities would strengthen the assumption that the SRM effect reflects common mechanisms underlying synaptic plasticity rather than reflecting modality-specific phenomena. A replication of previous findings showing robust potentiation of the visual evoked potential was evident, supporting the majority of previous work using similar paradigms, lending further support to the notion that high-frequent visual stimulation is a viable probe into LTP-like synaptic plasticity in the human visual cortex. The auditory evoked potentials (AEPs) did not, however, fully replicate previous work, though a significant increase of temporally later AEP components was found. In contrast to our hypothesis, there were no significant within-subject cross-modality correlations between the visual and auditory SRM. This lack of significant association might suggest that auditory and visual SRM depend on different mechanisms, and that further SRM studies on non-invasive LTP-like synaptic plasticity should focus on optimizing paradigms within the visual modality.
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Affiliation(s)
| | - Christoffer Hatlestad-Hall
- Department of Psychology, University of Oslo, Oslo, Norway.,Department of Neurology, Oslo University Hospital, Oslo, Norway
| | | | - Torgeir Moberget
- Department of Psychology, University of Oslo, Oslo, Norway.,Department of Neurology, Oslo University Hospital, Oslo, Norway
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12
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Guerra A, López-Alonso V, Cheeran B, Suppa A. Variability in non-invasive brain stimulation studies: Reasons and results. Neurosci Lett 2020; 719:133330. [DOI: 10.1016/j.neulet.2017.12.058] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/18/2017] [Accepted: 12/27/2017] [Indexed: 01/22/2023]
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Minkova L, Peter J, Abdulkadir A, Schumacher LV, Kaller CP, Nissen C, Klöppel S, Lahr J. Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation. Front Neurosci 2019; 13:841. [PMID: 31474818 PMCID: PMC6702284 DOI: 10.3389/fnins.2019.00841] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/26/2019] [Indexed: 12/23/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is a well-established tool in probing cortical plasticity in vivo. Changes in corticomotor excitability can be induced using paired associative stimulation (PAS) protocol, in which TMS over the primary motor cortex is conditioned with an electrical peripheral nerve stimulation of the contralateral hand. PAS with an inter-stimulus interval of 25 ms induces long-term potentiation (LTP)-like effects in cortical excitability. However, the response to a PAS protocol tends to vary substantially across individuals. In this study, we used univariate and multivariate data-driven methods to investigate various previously proposed determinants of inter-individual variability in PAS efficacy, such as demographic, cognitive, clinical, neurophysiological, and neuroimaging measures. Forty-one right-handed participants, comprising 22 patients with amnestic mild cognitive impairment (MCI) and 19 healthy controls (HC), underwent the PAS protocol. Prior to stimulation, demographic, genetic, clinical, as well as structural and resting-state functional MRI data were acquired. The two groups did not differ in any of the variables, except by global cognitive status. Univariate analysis showed that only 61% of all participants were classified as PAS responders, irrespective of group membership. Higher PAS response was associated with lower TMS intensity and with higher resting-state connectivity within the sensorimotor network, but only in responders, as opposed to non-responders. We also found an overall positive correlation between PAS response and structural connectivity within the corticospinal tract, which did not differ between groups. A multivariate random forest (RF) model identified age, gender, education, IQ, global cognitive status, sleep quality, alertness, TMS intensity, genetic factors, and neuroimaging measures (functional and structural connectivity, gray matter (GM) volume, and cortical thickness as poor predictors of PAS response. The model resulted in low accuracy of the RF classifier (58%; 95% CI: 42 - 74%), with a higher relative importance of brain connectivity measures compared to the other variables. We conclude that PAS variability in our sample was not well explained by factors known to influence PAS efficacy, emphasizing the need for future replication studies.
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Affiliation(s)
- Lora Minkova
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.,Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging, Medical Center - University of Freiburg, Freiburg, Germany
| | - Jessica Peter
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | - Ahmed Abdulkadir
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | - Lena V Schumacher
- Department of Medical Psychology and Medical Sociology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph P Kaller
- Freiburg Brain Imaging, Medical Center - University of Freiburg, Freiburg, Germany.,Department of Neuroradiology, Medical Center - Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph Nissen
- Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,University Hospital of Psychiatry and Psychotherapy, University Psychiatric Services, University of Bern, Bern, Switzerland.,Department of Neurology, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Stefan Klöppel
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.,Center for Geriatrics and Gerontology Freiburg, Medical Center - Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jacob Lahr
- Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging, Medical Center - University of Freiburg, Freiburg, Germany
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14
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Abuleil D, McCulloch DL, Thompson B. Older Adults Exhibit Greater Visual Cortex Inhibition and Reduced Visual Cortex Plasticity Compared to Younger Adults. Front Neurosci 2019; 13:607. [PMID: 31249506 PMCID: PMC6582629 DOI: 10.3389/fnins.2019.00607] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 05/27/2019] [Indexed: 12/14/2022] Open
Abstract
Recent evidence indicates that inhibition within the visual cortex is greater in older than young adults. Increased inhibition has been associated with reduced visual cortex plasticity in animal models. We investigated whether age-related increases in human visual cortex inhibition occur in conjunction with reduced visual cortex plasticity. Visual cortex inhibition was measured psychophysically using binocular rivalry alternation rates (AR) for dichoptic gratings. Slower ARs are associated with a greater concentration of the inhibitory neurotransmitter GABA within the human visual cortex. Visual cortex plasticity was measured using an established paradigm for induction of long-term potentiation (LTP) -like increases in visually evoked potential (VEP) amplitude. Following rapid visual stimulation, greater increases in VEP amplitude indicate greater visual cortex plasticity. The study involved two groups; young (18-40 years, n = 29) and older adults (60-80 years, n = 18). VEPs were recorded for a 1 Hz onset/offset checkerboard stimulus before and after 9 Hz visual stimulation with the same stimulus. ARs were slower in older than young adults. In contrast to most previous studies, VEP amplitudes were significantly reduced following the rapid visual stimulation for young adults; older adult VEP amplitudes were unaffected. Our AR results replicate previous observations of increased visual cortex inhibition in the older adults. Rapid visual stimulation significantly altered VEP amplitude in young adults, albeit in the opposite direction than predicted. VEP amplitudes did not change in older adults suggesting an association between increased inhibition and reduced plasticity within the human visual cortex.
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Affiliation(s)
- Dania Abuleil
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
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15
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Sanders PJ, Thompson B, Corballis PM, Maslin M, Searchfield GD. A review of plasticity induced by auditory and visual tetanic stimulation in humans. Eur J Neurosci 2018; 48:2084-2097. [PMID: 30025183 DOI: 10.1111/ejn.14080] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 06/10/2018] [Accepted: 07/04/2018] [Indexed: 12/01/2022]
Abstract
Long-term potentiation is a form of synaptic plasticity thought to play an important role in learning and memory. Recently noninvasive methods have been developed to induce and measure activity similar to long-term potentiation in humans. Sensory tetani (trains of quickly repeating auditory or visual stimuli) alter the electroencephalogram in a manner similar to electrical stimulation that results in long-term potentiation. This review briefly covers the development of long-term potentiation research before focusing on in vivo human studies that produce long-term potentiation-like effects using auditory and visual stimulation. Similarities and differences between traditional (animal and brain tissue) long-term potentiation studies and human sensory tetanization studies will be discussed, as well as implications for perceptual learning. Although evidence for functional consequences of sensory tetanization remains scarce, studies involving clinical populations indicate that sensory induced plasticity paradigms may be developed into diagnostic and research tools in clinical settings. Individual differences in the effects of sensory tetanization are not well-understood and provide an interesting avenue for future research. Differences in effects found between research groups that have emerged as the field has progressed are also yet to be resolved.
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Affiliation(s)
- Philip J Sanders
- Section of Audiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Brain Research New Zealand - Rangahau Roro Aotearoa, Auckland, New Zealand
| | - Benjamin Thompson
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,School of Optometry & Vision Science, University of Auckland, Auckland, New Zealand.,School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
| | - Paul M Corballis
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Psychology, University of Auckland, Auckland, New Zealand
| | | | - Grant D Searchfield
- Section of Audiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Brain Research New Zealand - Rangahau Roro Aotearoa, Auckland, New Zealand
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16
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Zak N, Moberget T, Bøen E, Boye B, Waage TR, Dietrichs E, Harkestad N, Malt UF, Westlye LT, Andreassen OA, Andersson S, Elvsåshagen T. Longitudinal and cross-sectional investigations of long-term potentiation-like cortical plasticity in bipolar disorder type II and healthy individuals. Transl Psychiatry 2018; 8:103. [PMID: 29795193 PMCID: PMC5966393 DOI: 10.1038/s41398-018-0151-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 01/19/2018] [Accepted: 03/26/2018] [Indexed: 12/12/2022] Open
Abstract
Visual evoked potential (VEP) plasticity is a promising assay for noninvasive examination of long-term potentiation (LTP)-like synaptic processes in the cerebral cortex. We conducted longitudinal and cross-sectional investigations of VEP plasticity in controls and individuals with bipolar disorder (BD) type II. VEP plasticity was assessed at baseline, as described previously (Elvsåshagen et al. Biol Psychiatry 2012), and 2.2 years later, at follow-up. The longitudinal sample with VEP data from both time points comprised 29 controls and 16 patients. VEP data were available from 13 additional patients at follow-up (total n = 58). VEPs were evoked by checkerboard reversals in two premodulation blocks before and six blocks after a plasticity-inducing block of prolonged (10 min) visual stimulation. VEP plasticity was computed by subtracting premodulation VEP amplitudes from postmodulation amplitudes. Saliva samples for cortisol analysis were collected immediately after awakening in the morning, 30 min later, and at 12:30 PM, at follow-up. We found reduced VEP plasticity in BD type II, that impaired plasticity was present in the euthymic phases of the illness, and that VEP plasticity correlated negatively with depression severity. There was a positive association between VEP plasticity and saliva cortisol in controls, possibly reflecting an inverted U-shaped relationship between cortisol and synaptic plasticity. VEP plasticity exhibited moderate temporal stability over a period of 2.2 years. The present study provides additional evidence for impaired LTP-like cortical plasticity in BD type II. VEP plasticity is an accessible method, which may help elucidate the pathophysiological and clinical significance of synaptic dysfunction in psychiatric disorders.
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Affiliation(s)
- Nathalia Zak
- 0000 0004 0389 8485grid.55325.34Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway ,0000 0004 1936 8921grid.5510.1Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Torgeir Moberget
- 0000 0004 0389 8485grid.55325.34Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway
| | - Erlend Bøen
- 0000 0004 0512 8628grid.413684.cDepartment of Psychiatry, Diakonhjemmet Hospital, Oslo, Norway
| | - Birgitte Boye
- 0000 0004 0389 8485grid.55325.34Section of Psychosocial Oncology, Division of Cancer Medicine, Oslo University Hospital, Oslo, Norway ,0000 0004 1936 8921grid.5510.1Department of Behavioural Sciences in Medicine, University of Oslo, Oslo, Norway
| | - Trine R. Waage
- 0000 0004 1936 8921grid.5510.1Department of Psychology, University of Oslo, Oslo, Norway
| | - Espen Dietrichs
- 0000 0004 1936 8921grid.5510.1Institute of Clinical Medicine, University of Oslo, Oslo, Norway ,0000 0004 0389 8485grid.55325.34Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Nina Harkestad
- 0000 0004 1936 7443grid.7914.bDepartment of Biological and Medical Pscyhology, University of Bergen, Bergen, Norway
| | - Ulrik F. Malt
- 0000 0004 1936 8921grid.5510.1Institute of Clinical Medicine, University of Oslo, Oslo, Norway ,0000 0004 0389 8485grid.55325.34Department of Research and Education, Oslo University Hospital, Oslo, Norway
| | - Lars T. Westlye
- 0000 0004 0389 8485grid.55325.34Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway ,0000 0004 1936 8921grid.5510.1Department of Psychology, University of Oslo, Oslo, Norway
| | - Ole A. Andreassen
- 0000 0004 0389 8485grid.55325.34Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway ,0000 0004 1936 8921grid.5510.1Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Stein Andersson
- 0000 0004 1936 8921grid.5510.1Department of Psychology, University of Oslo, Oslo, Norway
| | - Torbjørn Elvsåshagen
- Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway. .,Institute of Clinical Medicine, University of Oslo, Oslo, Norway. .,Department of Neurology, Oslo University Hospital, Oslo, Norway.
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17
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Jahshan C, Wynn JK, Mathalon DH, Green MF. Cognitive correlates of visual neural plasticity in schizophrenia. Schizophr Res 2017; 190:39-45. [PMID: 28336195 DOI: 10.1016/j.schres.2017.03.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/03/2017] [Accepted: 03/05/2017] [Indexed: 12/15/2022]
Abstract
Neuroplasticity may be an important treatment target to improve the cognitive deficits in schizophrenia (SZ). Yet, it is poorly understood and difficult to assess. Recently, a visual high-frequency stimulation (HFS) paradigm that potentiates electroencephalography (EEG)-based visual evoked potentials (VEP) has been developed to assess neural plasticity in the visual cortex. Using this paradigm, we examined visual plasticity in SZ patients (N=64) and its correlations with clinical symptoms, neurocognition, functional capacity, and community functioning. VEPs were assessed prior to (baseline), and 2-, 4-, and 20-min after (Post-1, Post-2, and Post-3, respectively) 2min of visual HFS. Cluster-based permutation tests were conducted to identify time points and electrodes at which VEP amplitudes were significantly different after HFS. Compared to baseline, there was increased negativity between 140 and 227ms for the early post-HFS block (average of Post-1 and Post-2), and increased positivity between 180 and 281ms for the late post-HFS block (Post-3), at parieto-occipital and occipital electrodes. The increased negativity in the early post-HFS block did not correlate with any of the measures, whereas increased positivity in the late post-HFS block correlated with better neurocognitive performance. Results suggest that SZ patients exhibit both short- and long-term plasticity. The long-term plasticity effect, which was present 22min after HFS, was evident relatively late in the VEP, suggesting that neuroplastic changes in higher-order visual association areas, rather than earlier short-term changes in primary and secondary visual cortex, may be particularly important for the maintenance of neurocognitive function in SZ.
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Affiliation(s)
- Carol Jahshan
- VISN-22 Mental Illness Research, Education and Clinical Center (MIRECC), VA Greater Los Angeles Healthcare System, Los Angeles, CA, United States; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, United States.
| | - Jonathan K Wynn
- VISN-22 Mental Illness Research, Education and Clinical Center (MIRECC), VA Greater Los Angeles Healthcare System, Los Angeles, CA, United States; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, United States
| | - Daniel H Mathalon
- San Francisco Department of Veterans Affairs Medical Center, San Francisco, CA, United States; Department of Psychiatry, University of California, San Francisco, CA, United States
| | - Michael F Green
- VISN-22 Mental Illness Research, Education and Clinical Center (MIRECC), VA Greater Los Angeles Healthcare System, Los Angeles, CA, United States; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, United States
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18
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Abstract
PURPOSE OF REVIEW The review aims at highlighting the additional benefit that can be gained from combining noninvasive brain stimulation as well as repetitive sensory stimulation protocols with MRI techniques to account for the intersubject variability observed in those treatments. Potentially, this should help to identify predictive patterns in the individual receptiveness to the treatment. RECENT FINDINGS Knowledge about the underlying physiological principles of excitability changes as induced by noninvasive brain stimulation or repetitive sensory stimulation is accumulating, revealing strong associations with plasticity processes at the synaptic level. In this context, MRI techniques, such as magnetic resonance spectroscopy and functional MRI, emerged as valuable tools for the qualitative assessment of baseline states and induced changes. Those physiological readouts can help explain the interindividual heterogeneity found in behavioural and/or clinical responses to the specific stimulation protocols. This knowledge will eventually translate, first, into the preliminary classification of study participants into treatment groups according to their neurophysiological baseline state and expected responses to a particular stimulation. Subsequently, this should also aid the optimization of stimulation protocols according to the classification outcome, resulting in retuned protocols for particular groups of study participants. SUMMARY The consistent MRI-based monitoring of stimulation effects in the neural network promises a considerable gain for the customization of intervention protocols with improved therapeutic potential and rehabilitative predictions.
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19
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Lahr J, Paßmann S, List J, Vach W, Flöel A, Klöppel S. Effects of Different Analysis Strategies on Paired Associative Stimulation. A Pooled Data Analysis from Three Research Labs. PLoS One 2016; 11:e0154880. [PMID: 27144307 PMCID: PMC4856316 DOI: 10.1371/journal.pone.0154880] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 04/20/2016] [Indexed: 02/02/2023] Open
Abstract
Paired associative stimulation (PAS) is a widely used transcranial magnetic stimulation (TMS) paradigm to non-invasively induce synaptic plasticity in the human brain in vivo. Altered PAS-induced plasticity has been demonstrated for several diseases. However, researchers are faced with a high inter- and intra-subject variability of the PAS response. Here, we pooled original data from nine PAS studies from three centers and analyzed the combined dataset of 190 healthy subjects with regard to age dependency, the role of stimulation parameters and the effect of different statistical methods. We observed no main effect of the PAS intervention over all studies (F(2;362) = 0.44; p = 0.644). The rate of subjects showing the expected increase of motor evoked potential (MEP) amplitudes was 53%. The PAS effect differed significantly between studies as shown by a significant interaction effect (F(16;362) = 1.77; p = 0.034) but post-hoc testing did not reveal significant effects after correction for multiple tests. There was a trend toward increased variability of the PAS effect in older subjects. Acquisition parameters differed across studies but without systematically influencing changes in MEP-size. The use of post/baseline quotients systematically indicated stronger PAS effects than post/baseline difference or the logarithm of the post/baseline quotient. The non-significant PAS effects across studies and a wide range of responder rates between studies indicate a high variability of this method. We were thus not able to replicate findings from a previous meta-analysis showing robust effects of PAS. No pattern emerged regarding acquisition parameters that at this point could guide future studies to reduce variability and help increase response rate. For future studies, we propose to report the responder rate and recommend the use of the logarithmized post/baseline quotient for further analyses to better address the possibility that results are driven by few extreme cases.
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Affiliation(s)
- Jacob Lahr
- Freiburg Brain Imaging, University Medical Center, Freiburg, Germany
- Department of Psychiatry and Psychotherapy, University Medical Center, Freiburg, Germany
- Department of Neurology, University Medical Center, Freiburg, Germany
| | - Sven Paßmann
- Department of Neurology, Charité Universitätsmedizin, Berlin, Germany
| | - Jonathan List
- Department of Neurology, Charité Universitätsmedizin, Berlin, Germany
| | - Werner Vach
- Center for Medical Biometry and Medical Informatics, University of Freiburg, Freiburg, Germany
| | - Agnes Flöel
- Department of Neurology, Charité Universitätsmedizin, Berlin, Germany
- Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany
- Cluster of Excellence NeuroCure, Charité Universitätsmedizin, Berlin, Germany
| | - Stefan Klöppel
- Freiburg Brain Imaging, University Medical Center, Freiburg, Germany
- Department of Psychiatry and Psychotherapy, University Medical Center, Freiburg, Germany
- Department of Neurology, University Medical Center, Freiburg, Germany
- Center of Geriatrics and Gerontology Freiburg, University Medical Center, Freiburg, Germany
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