1
|
Pasanta D, White DJ, He JL, Ford TC, Puts NA. GABA and glutamate response to social processing: a functional MRS feasibility study. NMR IN BIOMEDICINE 2024; 37:e5092. [PMID: 38154459 DOI: 10.1002/nbm.5092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 10/04/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023]
Abstract
Several studies have suggested that atypical social processing in neurodevelopmental conditions (e.g. autism) is associated with differences in excitation and inhibition, through changes in the levels of glutamate and gamma-aminobutyric acid (GABA). While associations between baseline metabolite levels and behaviours can be insightful, assessing the neurometabolic response of GABA and glutamate during social processing may explain altered neurochemical function in more depth. Thus far, there have been no attempts to determine whether changes in metabolite levels are detectable using functional MRS (fMRS) during social processing in a control population. We performed Mescher-Garwood point resolved spectroscopy edited fMRS to measure the dynamic response of GABA and glutamate in the superior temporal sulcus (STS) and visual cortex (V1) while viewing social stimuli, using a design that allows for analysis in both block and event-related approaches. Sliding window analyses were used to investigate GABA and glutamate dynamics at higher temporal resolution. The changes of GABA and glutamate levels with social stimulus were largely non-significant. A small decrease in GABA levels was observed during social stimulus presentation in V1, but no change was observed in STS. Conversely, non-social stimulus elicited changes in both GABA and glutamate levels in both regions. Our findings suggest that the current experimental design primarily captures effects of visual stimulation, not social processing. Here, we discuss the feasibility of using fMRS analysis approaches to assess changes in metabolite response.
Collapse
Affiliation(s)
- Duanghathai Pasanta
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
- Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - David J White
- Centre for Human Psychopharmacology & Swinburne Neuroimaging, School of Health Sciences, Swinburne University of Technology, Melbourne, Australia
| | - Jason L He
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Talitha C Ford
- Centre for Human Psychopharmacology & Swinburne Neuroimaging, School of Health Sciences, Swinburne University of Technology, Melbourne, Australia
- Cognitive Neuroscience Unit, Faculty of Health, Deakin University, Geelong, Australia
| | - Nicolaas A Puts
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| |
Collapse
|
2
|
Ehrhardt SE, Wards Y, Rideaux R, Marjańska M, Jin J, Cloos MA, Deelchand DK, Zöllner HJ, Saleh MG, Hui SCN, Ali T, Shaw TB, Barth M, Mattingley JB, Filmer HL, Dux PE. Neurochemical Predictors of Generalized Learning Induced by Brain Stimulation and Training. J Neurosci 2024; 44:e1676232024. [PMID: 38531634 PMCID: PMC11112648 DOI: 10.1523/jneurosci.1676-23.2024] [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: 09/05/2023] [Revised: 01/22/2024] [Accepted: 03/08/2024] [Indexed: 03/28/2024] Open
Abstract
Methods of cognitive enhancement for humans are most impactful when they generalize across tasks. However, the extent to which such "transfer" is possible via interventions is widely debated. In addition, the contribution of excitatory and inhibitory processes to such transfer is unknown. Here, in a large-scale neuroimaging individual differences study with humans (both sexes), we paired multitasking training and noninvasive brain stimulation (transcranial direct current stimulation, tDCS) over multiple days and assessed performance across a range of paradigms. In addition, we varied tDCS dosage (1.0 and 2.0 mA), electrode montage (left or right prefrontal regions), and training task (multitasking vs a control task) and assessed GABA and glutamate concentrations via ultrahigh field 7T magnetic resonance spectroscopy. Generalized benefits were observed in spatial attention, indexed by visual search performance, when multitasking training was combined with 1.0 mA stimulation targeting either the left or right prefrontal cortex (PFC). This transfer effect persisted for ∼30 d post intervention. Critically, the transferred benefits associated with right prefrontal tDCS were predicted by pretraining concentrations of glutamate in the PFC. Thus, the effects of this combined stimulation and training protocol appear to be linked predominantly to excitatory brain processes.
Collapse
Affiliation(s)
- Shane E Ehrhardt
- School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Yohan Wards
- School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Reuben Rideaux
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
- School of Psychology, The University of Sydney, Sydney, New South Wales 2050, Australia
| | - Małgorzata Marjańska
- Department of Radiology, Centre for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota 55455
| | - Jin Jin
- Centre for Advanced Imaging, The University of Queensland, St Lucia, Queensland 4072, Australia
- Siemens Healthcare Pty Ltd., Brisbane, Queensland 4006, Australia
| | - Martijn A Cloos
- Centre for Advanced Imaging, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Dinesh K Deelchand
- Department of Radiology, Centre for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota 55455
| | - Helge J Zöllner
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Muhammad G Saleh
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Steve C N Hui
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Tonima Ali
- School of Biomedical Engineering, The University of Sydney, Sydney, New South Wales 2050, Australia
- Brain and Mind Centre, The University of Sydney, Sydney, New South Wales 2050, Australia
| | - Thomas B Shaw
- Centre for Advanced Imaging, The University of Queensland, St Lucia, Queensland 4072, Australia
- School of Information Technology and Electrical Engineering, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Markus Barth
- Centre for Advanced Imaging, The University of Queensland, St Lucia, Queensland 4072, Australia
- School of Information Technology and Electrical Engineering, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Jason B Mattingley
- School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
- Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia
| |
Collapse
|
3
|
Bramson B, Meijer S, van Nuland A, Toni I, Roelofs K. Anxious individuals shift emotion control from lateral frontal pole to dorsolateral prefrontal cortex. Nat Commun 2023; 14:4880. [PMID: 37573436 PMCID: PMC10423291 DOI: 10.1038/s41467-023-40666-3] [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: 01/12/2023] [Accepted: 08/04/2023] [Indexed: 08/14/2023] Open
Abstract
Anxious individuals consistently fail in controlling emotional behavior, leading to excessive avoidance, a trait that prevents learning through exposure. Although the origin of this failure is unclear, one candidate system involves control of emotional actions, coordinated through lateral frontopolar cortex (FPl) via amygdala and sensorimotor connections. Using structural, functional, and neurochemical evidence, we show how FPl-based emotional action control fails in highly-anxious individuals. Their FPl is overexcitable, as indexed by GABA/glutamate ratio at rest, and receives stronger amygdalofugal projections than non-anxious male participants. Yet, high-anxious individuals fail to recruit FPl during emotional action control, relying instead on dorsolateral and medial prefrontal areas. This functional anatomical shift is proportional to FPl excitability and amygdalofugal projections strength. The findings characterize circuit-level vulnerabilities in anxious individuals, showing that even mild emotional challenges can saturate FPl neural range, leading to a neural bottleneck in the control of emotional action tendencies.
Collapse
Affiliation(s)
- Bob Bramson
- Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, 6525 EN, Nijmegen, The Netherlands.
- Behavioral Science Institute (BSI), Radboud University Nijmegen, 6525 HR, Nijmegen, The Netherlands.
| | - Sjoerd Meijer
- Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, 6525 EN, Nijmegen, The Netherlands
| | - Annelies van Nuland
- Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, 6525 EN, Nijmegen, The Netherlands
| | - Ivan Toni
- Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, 6525 EN, Nijmegen, The Netherlands
| | - Karin Roelofs
- Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, 6525 EN, Nijmegen, The Netherlands
- Behavioral Science Institute (BSI), Radboud University Nijmegen, 6525 HR, Nijmegen, The Netherlands
| |
Collapse
|
4
|
Rideaux R, Ehrhardt SE, Wards Y, Filmer HL, Jin J, Deelchand DK, Marjańska M, Mattingley JB, Dux PE. On the relationship between GABA+ and glutamate across the brain. Neuroimage 2022; 257:119273. [PMID: 35526748 PMCID: PMC9924060 DOI: 10.1016/j.neuroimage.2022.119273] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/13/2022] [Accepted: 04/29/2022] [Indexed: 01/27/2023] Open
Abstract
Equilibrium between excitation and inhibition (E/I balance) is key to healthy brain function. Conversely, disruption of normal E/I balance has been implicated in a range of central neurological pathologies. Magnetic resonance spectroscopy (MRS) provides a non-invasive means of quantifying in vivo concentrations of excitatory and inhibitory neurotransmitters, which could be used as diagnostic biomarkers. Using the ratio of excitatory and inhibitory neurotransmitters as an index of E/I balance is common practice in MRS work, but recent studies have shown inconsistent evidence for the validity of this proxy. This is underscored by the fact that different measures are often used in calculating E/I balance such as glutamate and Glx (glutamate and glutamine). Here we used a large MRS dataset obtained at ultra-high field (7 T) measured from 193 healthy young adults and focused on two brain regions - prefrontal and occipital cortex - to resolve this inconsistency. We find evidence that there is an inter-individual common ratio between GABA+ (γ-aminobutyric acid and macromolecules) and Glx in the occipital, but not prefrontal cortex. We further replicate the prefrontal result in a legacy dataset (n = 78) measured at high-field (3 T) strength. By contrast, with ultra-high field MRS data, we find extreme evidence that there is a common ratio between GABA+ and glutamate in both prefrontal and occipital cortices, which cannot be explained by participant demographics, signal quality, fractional tissue volume, or other metabolite concentrations. These results are consistent with previous electrophysiological and theoretical work supporting E/I balance. Our findings indicate that MRS-detected GABA+ and glutamate (but not Glx), are a reliable measure of E/I balance .
Collapse
Affiliation(s)
- Reuben Rideaux
- Queensland Brain Institute, The University of Queensland, St Lucia, Australia.
| | - Shane E Ehrhardt
- School of Psychology, The University of Queensland, St Lucia, Australia
| | - Yohan Wards
- School of Psychology, The University of Queensland, St Lucia, Australia
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, St Lucia, Australia
| | - Jin Jin
- Siemens Healthcare Pty Ltd, Brisbane, Australia; Center for Advanced Imaging, The University of Queensland, St Lucia, Australia
| | - Dinesh K Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
| | - Małgorzata Marjańska
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
| | - Jason B Mattingley
- Queensland Brain Institute, The University of Queensland, St Lucia, Australia; School of Psychology, The University of Queensland, St Lucia, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, St Lucia, Australia
| |
Collapse
|
5
|
Rideaux R. No balance between glutamate+glutamine and GABA+ in visual or motor cortices of the human brain: A magnetic resonance spectroscopy study. Neuroimage 2021; 237:118191. [PMID: 34023450 DOI: 10.1016/j.neuroimage.2021.118191] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 04/27/2021] [Accepted: 05/19/2021] [Indexed: 12/28/2022] Open
Abstract
Theoretical work, supported by electrophysiological evidence, asserts that a balance between excitation and inhibition (E/I) is critical for healthy brain function. In magnetic resonance spectroscopy (MRS) studies, the ratio of excitatory (glutamate) and inhibitory (γ-aminobutyric acid, GABA) neurotransmitters is often used as a proxy for this E/I balance. Recent MRS work found a positive correlation between GABA+ and Glx (glutamate+glutamine) in medial parietal cortex, providing validation for this proxy and supporting the link between the E/I balance observed in electrophysiology and that detected with MRS. Here we assess the same relationship, between GABA+ and Glx, in visual and motor cortices of male and female human participants. We find moderate to strong evidence that there is no positive correlation between these neurotransmitters in either location. We show this holds true when controlling for a range of other factors (i.e., demographics, signal quality, tissue composition, other neurochemicals) and regardless of the state of neural activity (i.e., resting/active). These results show that there is no brain-wide balance between excitatory and inhibitory neurotransmitters and indicates a dissociation between the E/I balance observed in electrophysiological work and the ratio of MRS-detected neurotransmitters.
Collapse
Affiliation(s)
- Reuben Rideaux
- Department of Psychology, Downing Street, University of Cambridge, UK; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.
| |
Collapse
|
6
|
Rideaux R, Mikkelsen M, Edden RAE. Comparison of methods for spectral alignment and signal modelling of GABA-edited MR spectroscopy data. Neuroimage 2021; 232:117900. [PMID: 33652146 PMCID: PMC8245134 DOI: 10.1016/j.neuroimage.2021.117900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/10/2021] [Accepted: 02/17/2021] [Indexed: 01/25/2023] Open
Abstract
Many methods exist for aligning and quantifying magnetic resonance spectroscopy (MRS) data to measure in vivo γ-aminobutyric acid (GABA). Research comparing the performance of these methods is scarce partly due to the lack of ground-truth measurements. The concentration of GABA is approximately two times higher in grey matter than in white matter. Here we use the proportion of grey matter within the MRS voxel as a proxy for ground-truth GABA concentration to compare the performance of four spectral alignment methods (i.e., retrospective frequency and phase drift correction) and six GABA signal modelling methods. We analyse a diverse dataset of 432 MEGA-PRESS scans targeting multiple brain regions and find that alignment to the creatine (Cr) signal produces GABA+ estimates that account for approximately twice as much of the variance in grey matter as the next best performing alignment method. Further, Cr alignment was the most robust, producing the fewest outliers. By contrast, all signal modelling methods, except for the single-Lorentzian model, performed similarly well. Our results suggest that variability in performance is primarily caused by differences in the zero-order phase estimated by each alignment method, rather than frequency, resulting from first-order phase offsets within subspectra. These results provide support for Cr alignment as the optimal method of processing MEGA-PRESS to quantify GABA. However, more broadly, they demonstrate a method of benchmarking quantification of in vivo metabolite concentration from other MRS sequences.
Collapse
Affiliation(s)
- Reuben Rideaux
- Department of Psychology, Downing Street, University of Cambridge, UK.
| | - Mark Mikkelsen
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Richard A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| |
Collapse
|
7
|
Ip IB, Bridge H. Investigating the neurochemistry of the human visual system using magnetic resonance spectroscopy. Brain Struct Funct 2021; 227:1491-1505. [PMID: 33900453 PMCID: PMC9046312 DOI: 10.1007/s00429-021-02273-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/09/2021] [Indexed: 11/29/2022]
Abstract
Biochemical processes underpin the structure and function of the visual cortex, yet our understanding of the fundamental neurochemistry of the visual brain is incomplete. Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive brain imaging tool that allows chemical quantification of living tissue by detecting minute differences in the resonant frequency of molecules. Application of MRS in the human brain in vivo has advanced our understanding of how the visual brain consumes energy to support neural function, how its neural substrates change as a result of disease or dysfunction, and how neural populations signal during perception and plasticity. The aim of this review is to provide an entry point to researchers interested in investigating the neurochemistry of the visual system using in vivo measurements. We provide a basic overview of MRS principles, and then discuss recent findings in four topics of vision science: (i) visual perception, plasticity in the (ii) healthy and (iii) dysfunctional visual system, and (iv) during visual stimulation. Taken together, evidence suggests that the neurochemistry of the visual system provides important novel insights into how we perceive the world.
Collapse
Affiliation(s)
- I Betina Ip
- Wellcome Centre for Integrative Neuroimaging, FMRIB Building, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Holly Bridge
- Wellcome Centre for Integrative Neuroimaging, FMRIB Building, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
| |
Collapse
|
8
|
Rideaux R. Low- and High-resolution Dynamic Analyses for Magnetic Resonance Spectroscopy Data. Bio Protoc 2021; 11:e3892. [PMID: 33732781 DOI: 10.21769/bioprotoc.3892] [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: 08/02/2020] [Revised: 11/27/2020] [Accepted: 11/30/2020] [Indexed: 11/02/2022] Open
Abstract
Magnetic resonance spectroscopy (MRS) can be used to measure in vivo concentrations of neurometabolites. This information can be used to identify neurotransmitter involvement in healthy (e.g., perceptual and cognitive processes) and unhealthy brain function (e.g., neurological and psychiatric illnesses). The standard approach for analyzing MRS data is to combine spectral transients acquired over a ~10 min scan to yield a single estimate that reflects the average metabolite concentration during that period. The temporal resolution of metabolite measurements is sacrificed in this manner to achieve a sufficient signal-to-noise ratio to produce a reliable estimate. Here we introduce two analyses that can be used to increase the temporal resolution of neurometabolite estimates produced from MRS measurements. The first analysis uses a sliding window approach to create a smoothed trace of neurometabolite concentration for each MRS scan. The second analysis combines transients across participants, rather than time, producing a single "group trace" with the highest possible temporal resolution achievable with the data. These analyses advance MRS beyond the current "static" application by allowing researchers to measure dynamic changes in neurometabolite concentration and expanding the types of questions that the technique can be used to address.
Collapse
Affiliation(s)
- Reuben Rideaux
- Department of Experimental Psychology, University of Cambridge, Cambridge, UK
| |
Collapse
|
9
|
Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review. J Clin Med 2020; 9:jcm9123985. [PMID: 33316960 PMCID: PMC7764820 DOI: 10.3390/jcm9123985] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/16/2020] [Accepted: 12/07/2020] [Indexed: 12/03/2022] Open
Abstract
Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process. Visual deficits in amblyopia and their neural mechanisms associated are revised, including visual acuity loss, contrast sensitivity reduction and stereopsis impairment. Likewise, the most appropriate stimuli according to the literature that should be used for an efficient rehabilitation of the amblyopic eye are described in detail, including optotypes, Gabor’s patches, random-dot stimuli and Vernier’s stimuli. Finally, the properties of these stimuli that can be modified during the visual training are discussed, as well as the psychophysical method of their presentation and the type of environment used (perceptual learning, dichoptic stimulation or virtual reality). Vision therapy using all these revised concepts can be an effective option for treating amblyopia or accelerating the treatment period when combining with patching. It is essential to adapt the stimuli to the patient’s individual features in both monocular and binocular training.
Collapse
|
10
|
Temporal Dynamics of GABA and Glx in the Visual Cortex. eNeuro 2020; 7:ENEURO.0082-20.2020. [PMID: 32571964 PMCID: PMC7429906 DOI: 10.1523/eneuro.0082-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/19/2020] [Accepted: 06/01/2020] [Indexed: 01/24/2023] Open
Abstract
Magnetic resonance spectroscopy (MRS) can be used in vivo to quantify neurometabolite concentration and provide evidence for the involvement of different neurotransmitter systems (e.g., inhibitory and excitatory) in sensory and cognitive processes. The relatively low signal-to-noise ratio of MRS measurements has shaped the types of questions that it has been used to address. In particular, temporal resolution is often sacrificed in MRS studies to achieve a signal sufficient to produce a reliable estimate of neurometabolite concentration. Here we apply novel analyses with large datasets from human participants (both sexes) to reveal the dynamics of GABA+ and Glx in visual cortex while participants are at rest (with eyes closed) and compare this with changes in posterior cingulate cortex from a previously collected dataset (under different conditions). We find that the dynamic concentration of GABA+ and Glx in visual cortex drifts in opposite directions; that is, GABA+ decreases while Glx increases over time. Further, we find that in visual, but not posterior cingulate cortex, the concentration of GABA+ predicts that of Glx 120 s later, such that a change in GABA+ is correlated with a subsequent opposite change in Glx. Together, these results expose novel temporal trends and interdependencies of primary neurotransmitters in visual cortex. More broadly, we demonstrate the feasibility of using MRS to investigate in vivo dynamic changes of neurometabolites.
Collapse
|
11
|
Shen L, Liu Z, Li Y. EEG based dynamic RDS recognition with frequency domain selection and bispectrum feature optimization. J Neurosci Methods 2020; 337:108650. [PMID: 32135211 DOI: 10.1016/j.jneumeth.2020.108650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/03/2020] [Accepted: 02/23/2020] [Indexed: 11/26/2022]
Abstract
BACKGROUND Stereopsis plays a vital role in many aspects of human daily life. Random-dot stereogram (RDS) is often used to detect stereoacuity and perform research on visual cognition. Electroencephalogram (EEG) is one of the commonly adopted visual cognition techniques due to its noninvasive collection. NEW METHOD In this study, a methodology named WPT-BED based on wavelet packet transform (WPT) and bispectral eigenvalues of differential signals (BED) is proposed, which can classify the three-pattern EEG signals evoked by dynamic RDS (DRDS). Specifically, the signals are decomposed into different frequency bands by WPT. The appropriate sub-bands are selected for reconstruction. Finally, the optimized bispectrum features are extracted for classification to achieve higher accuracy. RESULTS The classification performance of the proposed method in different periods of signal processing are investigated. The method WPT-BED has the highest classification accuracy 84.38%, and the average classification accuracy is 73.98%. The active channels with higher accuracy are focused on the visual pathway in the human cerebral cortex. COMPARISON WITH EXISTING METHODS Comparison with other methods for EEG signals classification is performed to identify the effectiveness of the proposed methodology. CONCLUSIONS The proposed methodology can effectively distinguish the EEG signals evoked by DRDS. It demonstrates the feasibility of DRDS recognition based on EEG.
Collapse
Affiliation(s)
- Lili Shen
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China.
| | - Zhijian Liu
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Yueping Li
- Tianjin Eye Hospital, Clinical College of Ophthalmology of Tianjin Medical University, Tianjin Key Laboratory of Ophthalmology and Vision Science, Tianjin 300020, China.
| |
Collapse
|