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Hendry ET, Balfe JG, Du P, Cakmak YO. Frequency-Specific Effects of Noninvasive Median Nerve Stimulation on Gastric Slow Wave Activity in Humans. Neuromodulation 2024:S1094-7159(24)00028-X. [PMID: 38466259 DOI: 10.1016/j.neurom.2023.12.005] [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: 09/04/2023] [Revised: 12/08/2023] [Accepted: 12/31/2023] [Indexed: 03/12/2024]
Abstract
OBJECTIVES The present study explored the effects of different frequencies of noninvasive median nerve stimulation (nMNS) on two autonomic responses: gastric slow waves under water-loading condition and heart rate variability (HRV). To the best of our knowledge, this is the first study to document the effects of different frequencies of nMNS on gastric slow waves (GSW) in humans under 5-minute water-loading condition. MATERIALS AND METHODS Twenty healthy adult participants were fitted with a noninvasive body-surface gastric mapping, electrocardiogram (ECG), and a transcutaneous electrical nerve stimulation device and administered with four different nMNS frequencies (placebo-0 Hz, 40 Hz, 120 Hz, and 200 Hz) on four separate counterbalanced days. After the baseline and stimulation periods, a 5-minute water-load test was applied, and a post-water-load period also is recorded for ECG and GSW activity. Time-domain HRV parameters are analyzed with repeated-measures one-way analysis of variance (ANOVA) and a post hoc Tukey multiple comparison test. Parameters that failed normality tests underwent a Freidman test with a post hoc Dunn multiple comparison test. GSW data are analyzed with repeated-measures mixed-effects ANOVA. RESULTS In empty stomach (baseline vs stimulation), only the 40-Hz frequency statistically significantly (p = 0.0129) increased GSW amplitude in comparison with its own baseline. In full (distended) stomach, 40-Hz and 200-Hz stimulations showed a statistically significant difference (post hoc multiple comparison adjusted, p = 0.0016 and p = 0.0183, respectively) in the Gastric Rhythm Index in comparison with the change obtained by placebo stimulation (baseline vs poststimulation periods); 120-Hz nMNS showed a statistically significant difference (p = 0.0300) in the stress index in comparison with the decrease observed in the placebo group. However, 120-Hz nMNS did not induce a statistically significant change in gastric electrical activity compared to placebo stimulation. The nMNS did not follow the linear "dose-response" relationship between nMNS frequency and gastric/HRV parameters. CONCLUSIONS The 40-Hz and 200-Hz nMNS frequencies showed the most promising results in response to gastric distension, in addition to 40 Hz for an empty stomach. Further research is essential to explore the potential therapeutic effects of these frequencies on gastric diseases such as gastroparesis, gastroesophageal reflux disease, and functional dyspepsia that can be used in wrist wearables.
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Affiliation(s)
| | | | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Yusuf Ozgur Cakmak
- Cakmak Lab, Department of Anatomy, University of Otago, Dunedin, New Zealand; Center for Bioengineering-Point-of-Care Technologies, University of Otago, Dunedin, New Zealand; Medtech Core New Zealand-Interventional Technologies Theme, Auckland, New Zealand; Centre for Health Systems and Technology, University of Otago, Dunedin, New Zealand.
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Chang YC, Chen CM, Lay IS, Lee YC, Tu CH. The effects of laser acupuncture dosage at PC6 (Neiguan) on brain reactivity: a pilot resting-state fMRI study. Front Neurosci 2023; 17:1264217. [PMID: 37901421 PMCID: PMC10600496 DOI: 10.3389/fnins.2023.1264217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/27/2023] [Indexed: 10/31/2023] Open
Abstract
Previous studies indicated that laser acupuncture (LA) may effectively treat various medical conditions. However, brain responses associated with LA intervention have not been fully investigated. This study is focused on the effect of LA with different energy density (ED) in brain using resting-state functional magnetic resonance imaging (fMRI). We hypothesized that different ED would elicit various brain responses. We enrolled healthy adults participants and selected bilateral PC6 (Neiguan) as the intervention points. LA was applied, respectively, with ED of 0, 7.96, or 23.87 J/cm2. Two 500-s resting-state fMRI scans were acquired before and after intervention, respectively. The functional connectivity (FC) was calculated between autonomic nerve system-regulation associated brainstem structures and other brain regions. Compared to other dosages, the FC between rostral ventrolateral medulla and orbitofrontal cortex has more enhanced; the FC between caudal ventrolateral medulla, nucleus of the solitary tract/nucleus ambiguus, and dorsal motor nucleus of the vagus and somatosensory area has more weakened when ED was 23.87 J/cm2. Different dosages of LA have demonstrated varied regions of FC changes between regions of interest and other brain areas, which indicated that variations in EDs might influence the clinical efficacy and subsequent impacts through distinct neural pathways within the brain.
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Affiliation(s)
- Yi-Chuan Chang
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, Taiwan
- Department of Chinese Medicine, China Medical University Beigang Hospital, Yunlin, Taiwan
| | - Chun-Ming Chen
- Department of Medical Imaging, China Medical University Hospital, Taichung, Taiwan
| | - Ing-Shiow Lay
- Department of Chinese Medicine, China Medical University Beigang Hospital, Yunlin, Taiwan
- School of Post-Baccalaureate Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yu-Chen Lee
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, Taiwan
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
- Department of Chinese Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Cheng-Hao Tu
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, Taiwan
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Gunasekara N, Gaeta G, Levy A, Boot E, Tachtsidis I. fNIRS neuroimaging in olfactory research: A systematic literature review. Front Behav Neurosci 2022; 16:1040719. [PMID: 36620865 PMCID: PMC9815777 DOI: 10.3389/fnbeh.2022.1040719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/04/2022] [Indexed: 12/24/2022] Open
Abstract
There are a number of key features which make olfaction difficult to study; subjective processes of odor detection, discrimination and identification, and individualistic odor hedonic perception and associated odor memories. In this systematic review we explore the role functional near-infrared spectroscopy (fNIRS) has played in understanding olfactory perception in humans. fNIRS is an optical neuroimaging technique able to measure changes in brain hemodynamics and oxygenation related to neural electrical activity. Adhering to PRISMA guidelines, results of this search found that generally the majority of studies involving healthy adult subjects observed increased activity in response to odors. Other population types were also observed, such as infants, individuals with autism, attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), mild cognitive impairment (MCI) and dysosmia. fNIRS coverage heavily favored the prefrontal cortex, temporal and parietal regions. This review finds that odor induced cortical activation is dependent on multiple factors, such as odorant type, gender and population type. This review also finds that there is room for improvement in areas such as participant diversity, use of wearable fNIRS systems, physiological monitoring and multi-distance channels.
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Affiliation(s)
- Natalie Gunasekara
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom,*Correspondence: Natalie Gunasekara
| | - Giuliano Gaeta
- Health and Well-being Centre of Excellence, Givaudan UK Limited, Ashford, United Kingdom
| | - Andrew Levy
- MetaboLight Ltd., London, United Kingdom,Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom
| | | | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom,MetaboLight Ltd., London, United Kingdom
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Maharjan A, Khwaounjoo P, Peng M, Cakmak YO. Non-contact neuromodulation of the human autonomic nervous system function via different odors: Sex, menstrual cycle, and odor dose- and duration-specific effects. Front Neurosci 2022; 16:950282. [PMID: 36312014 PMCID: PMC9596915 DOI: 10.3389/fnins.2022.950282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 08/17/2022] [Indexed: 11/24/2022] Open
Abstract
In recent decades, it has been uncovered that the autonomic nervous system (ANS) can be influenced using non-contact neuromodulation via odor stimulation. Increasing parasympathetic-vagal activation of the ANS is integral to improving the sympathovagal balance between the sympathetic- and parasympathetic nervous systems, which is often imbalanced in several chronic inflammatory disorders, such as rheumatoid arthritis and inflammatory bowel diseases. Although research into olfactory stimulation has been observed on the ANS, it is still lacking in the exploration of odor concentration and odor-specific effects. This is particularly the case as research has not utilized specified tools, such as the olfactometer to provide precise odor delivery. Furthermore, no research has compared the results in separate sex cohorts to investigate the role of sex or the menstrual stage on the subsequent interactions. In this study, we investigated the olfactory stimulation effects of four natural odors (mushroom, lavender, jasmine, and rose) in three concentrations (low, moderate, and high) on the ANS. To observe activity from the ANS, we used an electrocardiogram (ECG) based heart rate variability (HRV) and eye-tracker technology (pupil diameter). We found for the first time in literature that there were acute dose- and duration-specific odor effects of odors on the ANS. We also found sex and menstrual cycle effects in this interaction. Furthermore, there were stark distinctions in sympathovagal activity dependent ANS activation (HRV) in comparison to the oculomotor nerve-parasympathetic/cervical sympathetic nerves dependent ANS responses (pupil diameter). Sympathovagal activity dependent HRV showed odor, sex, and menstrual-stage interactions in both divisions of the ANS while the pupil responses only indicated increased sympathetic activation. These results shed light on the use of odor-specific stimulation to modulate the ANS activity in the context of sex and the menstrual stage. Future studies should be performed using a chronic odor delivery design to investigate the long-term effects of odors on the ANS.
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Affiliation(s)
- Ashim Maharjan
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Prashanna Khwaounjoo
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Medical Technologies Centre of Research Excellence, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Mei Peng
- Sensory Neuroscience Laboratory, Department of Food Science, University of Otago, Dunedin, New Zealand
| | - Yusuf Ozgur Cakmak
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Medical Technologies Centre of Research Excellence, Auckland, New Zealand
- Brain Health Research Centre, Dunedin, New Zealand
- Centre for Bioengineering and Nanotechnology, Point of Care Technologies, University of Otago, Dunedin, New Zealand
- *Correspondence: Yusuf Ozgur Cakmak,
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Maharjan A, Peng M, Russell B, Cakmak YO. Investigation of the Optimal Parameters of Median Nerve Stimulation, Using a Variety of Stimulation Methods, and Its Effects on Heart Rate Variability: A Systematic Review. Neuromodulation 2022; 25:1268-1279. [DOI: 10.1016/j.neurom.2021.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 11/30/2022]
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Maharjan A, Peng M, Cakmak YO. The effects of frequency-specific, non-invasive, median nerve stimulation on food-related attention and appetite. Appetite 2021; 169:105807. [PMID: 34798222 DOI: 10.1016/j.appet.2021.105807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 12/17/2022]
Abstract
Median nerve stimulation (MNS) in the existing literature has been used for treating gastrointestinal disorders and amelioration of nausea and vomiting. Recently, studies have shown that MNS can also exert effects on olfactory performances and corresponding anatomical regions through the activation of vagal pathways. This study aimed to test effects of specific frequencies of MNS on food-related attention and appetite. The experiment used an odourised, dot probe task for testing food-related attention and a combination of behavioural (i.e., visual analogue scales; VAS) and physiological approaches (i.e., electrocardiograph; ECG - root mean square of successive differences between normal heartbeats-RMSSD: parasympathetic nervous system activation (RMSSD), stress index-SI: sympathetic nervous system activation) for measuring hunger, appetite, and satiation. Twenty-four healthy, male adults completed a VAS and dot probe task before and after receiving either 40 Hz-, 80 Hz-, 120 Hz MNS or sham (control) across four different sessions with continuous ECG recording throughout each session. Data from the dot probe task were analysed using repeated-measures ANOVA, while pair-wise tests were used for ECG recordings and VAS. Improvements on the dot probe task, not specific to odour-food congruence were found after 40 Hz MNS (p-value = 0.048; strong effect size (0.308 partial eta squared)) while increased ratings of hunger (VAS) (p-value = 0.03, small effect size (0.47 Cohen-D)) and RMSSD scores (p-value < 0.001; medium effect size (0.76 Cohen-D)) were found after 120 Hz MNS. These findings implore further testing of MNS frequency parameters on improving RMSSD, a characteristic marker of measuring parasympathetic/autonomic nervous system activation pertaining to the vagal network. Furthermore, improving sympathovagal balance is associated with cardiovascular benefits in numerous health-related conditions such as obesity, hypertension and diabetes.
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Affiliation(s)
- Ashim Maharjan
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Mei Peng
- Sensory Neuroscience Laboratory, Department of Food Science, University of Otago, Dunedin, New Zealand
| | - Yusuf O Cakmak
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, Dunedin, New Zealand; Medical Technologies Centre of Research Excellence, Auckland, New Zealand.
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Activation of the orbitofrontal cortex by both meditation and exercise: A near-infrared spectroscopy study. PLoS One 2021; 16:e0247685. [PMID: 33621250 PMCID: PMC7901739 DOI: 10.1371/journal.pone.0247685] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 02/10/2021] [Indexed: 12/15/2022] Open
Abstract
In some types of meditation, such as mindfulness and Zen, breathing is the focus of attention, whereas during an excessive, short-period of anaerobic exercise, the muscles become the focus of attention. Thus, during both efforts, one’s attention is focused on a certain feature of the body. Both meditation and exercise generally provide mental refreshment to humans. We hypothesized that the same brain regions are activated by both efforts in humans. To examine this hypothesis, we engaged participants in 3 tasks: meditation, exercise, and a control task. After each task, the participants underwent a 2-back test to concentrate their thoughts, while changes in their blood hemoglobin levels were simultaneously monitored using near-infrared spectroscopy (NIRS). Seventeen participants (20–24 years of age; 11 men, 6 women) were enrolled. We applied a fast-Fourier transform (FFT) analysis to the NIRS wave data and calculated the correlation coefficients of the FFT data between (1) meditation and control, (2) exercise and control, and (3) meditation and exercise, at the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), brain areas that are generally involved in mental refreshment. A significant difference in the correlation coefficients between the OFC and DLPFC was detected in the meditation and exercise analysis, and signal source analysis confirmed that the NIRS waves spread from the right and left OFC edges (i.e., right and left temples) toward the center. Our results suggest that both meditation and exercise activate the OFC, which is involved in emotional reactions and motivation behavior, resulting in mental refreshment.
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Cakmak YO, Nazim K, Thomas C, Datta A. Optimized Electrode Placements for Non-invasive Electrical Stimulation of the Olfactory Bulb and Olfactory Mucosa. Front Neurosci 2020; 14:581503. [PMID: 33262684 PMCID: PMC7688457 DOI: 10.3389/fnins.2020.581503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/07/2020] [Indexed: 11/13/2022] Open
Abstract
The olfactory system is known to be dysfunctional in the early stages of Parkinson's disease (PD) and Alzheimer's disease (AD). It is also shown that intact olfactory function can be a key role player for regaining consciousness after brain injuries. Modulation of the olfactory regions has been attempted successfully with electrical stimulation over the years, either directly (transethmoidally, intraoperatively, internasally, etc.) or indirectly through the vagus nerve. We sought to develop a means of delivering optimized electrical stimulation to the olfactory region in a non-invasive fashion and in a way that is simpler, easier, and less cumbersome. The ultimate goal was to develop a system that would allow easier testing in future clinical trials presenting an opportunity to fully develop this potential treatment option. We devised six potential electrode placements leveraging commonly accepted facts of electrical stimulation, easier access through relatively higher conductive pathways into the brain, and practicality. Using an ultra-high-resolution finite element model, we screened each one of these montages for their ability to target the olfactory regions primarily and thereafter for select sub-cortical regions implicated in the pathogenesis of PD and AD. Modeling results indicate that some placements do result in inducing meaningful electric field magnitudes in the regions of interest. A practical headgear concept is proposed to realize the most ideal configuration. Our results pave the way for developing the first non-invasive electrical stimulation wearable system for targeting the olfactory regions which can help to alleviate the symptoms or suppress the progression of these neurological disorders.
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Affiliation(s)
- Yusuf Ozgur Cakmak
- Department of Anatomy, University of Otago, Dunedin, New Zealand
- Brain Health Research Center, Dunedin, New Zealand
- Medical Technologies Center of Research Excellence, Auckland, New Zealand
- Centre for Health Systems and Technology, Dunedin, New Zealand
| | - Kamran Nazim
- Research and Development, Soterix Medical, New York, NY, United States
| | - Chris Thomas
- Research and Development, Soterix Medical, New York, NY, United States
| | - Abhishek Datta
- Research and Development, Soterix Medical, New York, NY, United States
- City College of New York, New York, NY, United States
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Cakmak YO. Concerning Auricular Vagal Nerve Stimulation: Occult Neural Networks. Front Hum Neurosci 2019; 13:421. [PMID: 31920585 PMCID: PMC6920183 DOI: 10.3389/fnhum.2019.00421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/13/2019] [Indexed: 11/27/2022] Open
Abstract
Auricular vagal nerve stimulation (AVNS) is an evolving neuromodulation technology that has a wide range of therapeutic applications across multiple disciplines of medical science. To date, AVNS results had been interpreted in the context of a monolog concept of the auricular branch of the vagus nerve (ABVN): that this is the sole network of the mechanism of action and/or structure in the auricular area of the stimulation in the context of activations in the brainstem nuclei, including the nucleus tractus solitarius (NTS), locus coeruleus (LC), trigeminal brainstem nuclei, and the nucleus cuneatus. This review considers the overlooked aspects of neural networks, connections, hijacking axons from cranial nerves and cervical sympathetic ganglions, the inhomogeneous distribution of perivascular sympathetic nerves, and intrinsic/extrinsic auricular muscles in the auricular zone that can explain the vagal and non-vagal nucleus activations in AVNS. In addition, the unique cortical representation of the human ear and interspecies differences in the auricula are discussed. The detailed auricular anatomy of the AVNS zone explored in the present study references structural and functional neural network information to overcome default designs and misinterpretations of existing research on AVNS to provide a better foundation for future investigations that use this modality.
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Affiliation(s)
- Yusuf Ozgur Cakmak
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Centre for Health Systems and Technologies, University of Otago, Dunedin, New Zealand.,Medical Technologies Centre of Research Excellence, Auckland, New Zealand
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