Cold Face Immersion - Diving Reflex Vagal Activation
1 Panneton and Gan 2020 — Mammalian Diving Response: Neural Circuitry (0.85)
Full Citation:: Panneton WM, Gan Q. The mammalian diving response: inroads to its neural control. Frontiers in Neuroscience. 2020;14:524. DOI:: 10.3389/fnins.2020.00524 PMID:: 32581683 Published:: June 5, 2020 Study Design:: Comprehensive review with primary neuroanatomical data Key Findings::
- Diving response described as the most powerful autonomic reflex known
- Reflex circuit: trigeminal nerve (anterior ethmoidal branch, V1) → medullary dorsal horn → NTS (ventrolateral subnucleus) → nucleus ambiguus (vagal efferent) + RVLM (sympathetic)
- Atropine or vagal cold block abolishes diving bradycardia
- Reflex alters baroreceptor and chemoreceptor homeostasis during diving
- Proposed as model system for SIDS, migraine, stroke, and arrhythmia researchConclusion: The mammalian diving reflex is mediated by a medullary circuit that simultaneously activates vagal (bradycardia) and sympathetic (vasoconstriction) efferents via trigeminal→NTS→nucleus ambiguus pathway. Limitations: Animal model data (rat, muskrat) — human extrapolation requires caution. No direct clinical application data. Certainty Assessment::
- *high* Quality: High — NIH-funded; authoritative review from lab with 30+ years of DR research
- *high* Sample: Animal models — extensive neuroanatomical mapping
- *high* Replication: Consistent across multiple species and techniques
- *medium* Limitations: Animal model data; mechanism well-established but human clinical translation limited2 Heath and Downey 1990 — Cold Face Test for Clinical Autonomic Assessment (0.70)
Full Citation:: Heath ME, Downey JA. The cold face test (diving reflex) in clinical autonomic assessment: methodological considerations and repeatability of responses. Clinical Science. 1990;78(2):139–147. DOI:: 10.1042/cs0780139 PMID:: 2155739 Published:: February 1990 Study Design:: Methodological study with controlled experimental protocols Sample Size:: N=16 healthy adults (9 female, 7 male), age 21–35 Key Findings::
- Optimal parameters: 0°C compresses applied bilaterally for 40s produced maximal bradycardia and peripheral vasoconstriction
- 22% reduction in heart rate; finger blood flow ↓72%, toe ↓59%, calf ↓44%
- Good within-subject repeatability across different days, times, and seasons
- Significant between-subject variability noted
- 0°C well-tolerated by all subjects; 120s application objectionable to someConclusion: Standardized cold face test (0°C, 40s, bilateral) provides reproducible autonomic assessment and is well-tolerated in healthy adults. Limitations: Healthy subjects only. No autonomic dysfunction populations studied. Certainty Assessment::
- *medium-high* Quality: High — rigorous methodology in peer-reviewed journal
- *medium* Sample: N=16 (moderate for methodological study)
- *medium-high* Replication: Good within-subject repeatability demonstrated
- *medium* Limitations: Healthy subjects only; no pathological populations3 Gorini Pereira et al. 2024 — Temperature Threshold for Parasympathetic Activation (0.75)
Full Citation:: Gorini Pereira F, McBryde M, Reynolds M, Sackett JR, Chapman CL, Gideon EA, Schlader ZJ, Johnson BD. Activation of cardiac parasympathetic and sympathetic activity occurs at different skin temperatures during face cooling. American Journal of Physiology — Regulatory, Integrative and Comparative Physiology. 2024;326(5):R357–R369. DOI:: 10.1152/ajpregu.00196.2023 PMID:: 38436059 Published:: March 4, 2024 Study Design:: Dose-response temperature threshold study Sample Size:: N=12 healthy (4 female, 8 male), age 25±3 Key Findings::
- Parasympathetic activation (RMSSD ↑, HF ↑) occurred ONLY at 0°C
- Sympathetic activation (MAP ↑) began at ≤7°C (13.1±10.3 mmHg) and increased at 0°C (25.2±7.8 mmHg)
- RMSSD increased 160.6±208.9 ms at 0°C; HF power 11,450±14,555 ms²
- Peak sympathetic activation reached at higher skin temperature than peak parasympathetic — temperature dissociation
- Warmer temperatures (10–15°C) produced sympathetic activation WITHOUT parasympathetic engagementConclusion: 0°C is required for reliable vagal parasympathetic engagement during face cooling. Warmer temperatures may produce sympathetically-dominated responses. Limitations: Healthy subjects only. Sequential temperature steps (not randomized). Small sample. Certainty Assessment::
- *medium-high* Quality: High — systematic dose-response design in respected journal
- *medium* Sample: N=12 (moderate)
- *medium* Replication: Single study — requires independent replication
- *medium* Limitations: Healthy subjects; sequential order; small N4 Shamsuzzaman et al. 2014 — Simulated Diving: Sympathetic and Vagal Synergy (0.70)
Full Citation:: Shamsuzzaman A, Ackerman MJ, Kuniyoshi FS, Accurso V, Davison D, Amin RS, Somers VK. Sympathetic nerve activity and simulated diving in healthy humans. Autonomic Neuroscience. 2014;181:74–78. DOI:: 10.1016/j.autneu.2013.12.001 PMID:: 24368150 Published:: April 2014 Study Design:: Experimental study with microneurography (direct MSNA measurement) Sample Size:: N=56 healthy (24 female, 32 male), mean age 39 Key Findings::
- Facial cold + apnea (simulated diving) produces synergistic sympathetic-parasympathetic activation exceeding sum of individual stimuli
- MSNA (muscle sympathetic nerve activity) increased markedly in early AND late phases
- Significant bradycardia observed only in late phase of simulated diving
- BP and vascular resistance increased substantially
- Combined stimulus more powerful than face cold or apnea aloneConclusion: Simulated diving is a powerful stimulus to sympathetic nerve traffic with late-phase bradycardia, revealing synergistic autonomic co-activation. Limitations: Healthy subjects only. Facial cold + apnea combination — not pure cold face immersion. Certainty Assessment::
- *medium-high* Quality: High — direct MSNA recording (gold standard)
- *high* Sample: N=56 (largest single-study sample in this literature)
- *medium* Replication: Mayo Clinic study — limited independent replication
- *medium* Limitations: Healthy subjects; combined stimulus not pure face cooling5 Kinoshita et al. 2006 — Cold-Water Face Immersion Isolates Vagal Bradycardia (0.55)
Full Citation:: Kinoshita T, Nagata S, Baba R, Kohmoto T, Iwagaki S. Cold-water face immersion per se elicits cardiac parasympathetic activity. Circulation Journal. 2006;70(6):773–776. DOI:: 10.1253/circj.70.773 PMID:: 16723802 Published:: June 2006 Study Design:: Experimental study with isolation of face immersion from confounding factors Sample Size:: N=8 healthy volunteers Key Findings::
- Cold-water face immersion bradycardia attributed solely to cardiac vagal activity
- Vagal activation independent of body position change (bending over basin) and breath-holding
- Wavelet transform HRV showed significantly increased high-frequency power only with cold (not warm) water
- R-R interval prolongation only significant with cold water + breath-holding combinationConclusion: Cold-water face immersion produces bradycardia via pure vagal activation, dissociable from postural and respiratory confounds. Limitations: Very small N=8. No replication. Healthy subjects only. Certainty Assessment::
- *medium* Quality: Medium — controlled design in peer-reviewed journal
- *low* Sample: N=8 (very small)
- *low* Replication: Single study; no independent replication
- *medium* Limitations: Small sample; healthy subjects only6 Al Haddad et al. 2010 — Cold Water Face Immersion Accelerates Post-Exercise Vagal Recovery (0.60)
Full Citation:: Al Haddad H, Laursen PB, Ahmaidi S, Buchheit M. Influence of cold water face immersion on post-exercise parasympathetic reactivation. European Journal of Applied Physiology. 2010;108(3):599–606. DOI:: 10.1007/s00421-009-1253-9 PMID:: 19882167 Published:: October 31, 2009 (Epub) Study Design:: Randomized crossover intervention Sample Size:: N=13 healthy men Key Findings::
- Cold water face immersion after exercise accelerated parasympathetic reactivation
- LnHF higher (p=0.004); Ln rMSSD higher (p=0.026)
- Heart rate recovery (HRR) faster (p=0.002)
- Immediate vagal enhancement within 5-minute recovery windowConclusion: Cold water face immersion is a simple and efficient method for accelerating post-exercise parasympathetic reactivation in healthy individuals. Limitations: Healthy males only. Post-exercise context — not directly generalizable to resting baseline. Certainty Assessment::
- *medium* Quality: Medium — randomized crossover in peer-reviewed journal
- *medium* Sample: N=13 (moderate)
- *low* Replication: Single study; no independent replication
- *medium* Limitations: Healthy males only; post-exercise context7 Schlader et al. 2016 — Prolonged Face Cooling: Two-Phase Autonomic Response (0.65)
Full Citation: Schlader ZJ, Coleman GL, Sackett JR, Sarker S, Johnson BD. Sustained increases in blood pressure elicited by prolonged face cooling in humans. American Journal of Physiology — Regulatory, Integrative and Comparative Physiology. 2016;311(4):R643–R648. DOI:: 10.1152/ajpregu.00164.2016 PMID:: 27511278 Published:: August 10, 2016 (Epub) Study Design:: Sham-controlled experimental study Sample Size:: N=10 healthy adults Key Findings::
- Two-phase response: RMSSD ↑ 61→165 ms (first 2 min) then returned to baseline
- MAP ↑ 83→106 mmHg (sustained entire 15 min)
- Forearm vascular resistance ↑ significantly (18.3→26.6 units)
- Facial skin temp ↓ 34→13°C with 0°C ice bag
- Sham (34°C) produced no changesConclusion: Face cooling produces differential time-dependent autonomic activation: brief parasympathetic surge (peak ~2 min) followed by sustained sympathetic vasoconstriction and blood pressure elevation. Limitations: N=10 healthy. Ice bag not full immersion. Vagal index (RMSSD) only time-domain. Certainty Assessment::
- *medium* Quality: Medium — well-controlled sham design
- *low* Sample: N=10 (small)
- *low* Replication: Single study — no independent replication
- *medium* Limitations: Small sample; healthy subjects; 15-min duration only8 Martinez et al. 2025 — Breath-Hold Diving for Cardiac Vagal Tone Conditioning (0.55)
Full Citation:: Martinez P, Dutschmann M, Epercieux V, Gourjon G, Joulia F. Breath-hold diving as a tool to harness a beneficial increase in cardiac vagal tone. Respiratory Physiology and Neurobiology. 2025;334:104416. DOI:: 10.1016/j.resp.2025.104416 PMID:: 40096873 Published:: March 15, 2025 (Epub) Study Design:: Narrative review with Hebbian plasticity framework Key Findings::
- Trigeminal afferents (nose/forehead) → pre-Bötzinger complex and Kölliker-Fuse nucleus → cardiac vagal motor neurons
- Volitional glottal closure during breath-hold appropriates respiratory HRV core network to generate diving bradycardia
- Hebbian plasticity within respirHRV/diving core circuit → regular training may yield permanent increase in cardiac vagal tone
- Breath-hold diving does not cause structural cardiac remodeling (unlike other exercise)
- Proposed as safe non-invasive approach for sympathetic hyperactivityConclusion: Regular breath-hold diving exercise may induce sustained vagal enhancement via plasticity at NTS-vagal synapse, potentially useful for conditions with sympathetic hyperactivity. Limitations: Narrative review — no primary data. Breath-hold diving (not pure face immersion). No clinical trial evidence. Certainty Assessment::
- *medium* Quality: Medium — review in peer-reviewed journal
- *low* Sample: No primary data — theoretical framework
- *low* Replication: Proposal — no clinical replication
- *medium* Limitations: Review only; no patient data; extrapolation required9 Zaproudil et al. 2020 — Cold Face Immersion and Vagal Stimulation (0.60)
Full Citation:: Zaproudil N, et al. Cold face immersion stimulates vagus nerve and increases parasympathetic tone. Auton Neurosci. 2020;224:102656. DOI:: 10.1016/j.autneu.2019.102656 PMID:: 31727630 Published:: 2020 Study Design: Experimental study Sample Size: Not specified in abstract Key Findings:
- Cold face immersion (diving reflex) increases HRV
- Parasympathetic dominance increased
- Trigeminal nerve → nucleus tractus solitarius → vagal activation
- Non-invasive vagal stimulation method
- Alternative to whole-body cold exposureConclusion: Cold face immersion provides non-invasive vagal stimulation and parasympathetic activation, potentially safer than whole-body cryotherapy. Limitations: Healthy subjects only — ME/CFS autonomic instability unknown. Sample size not specified in abstract. Replication and temperature details limited. Certainty Assessment::
- *medium* Quality: Medium — peer-reviewed journal, experimental design
- *medium* Sample: Not specified — insufficient data
- *low* Replication: Single study — no independent replication
- *medium* Limitations: Healthy population only, no ME/CFS data, sample size unclear10 Cervenka et al. 2017 — Kynurenines in Exercise, Inflammation, and Mental Health (0.95)
Full Citation:: Cervenka I, Agudelo LZ, Ruas JL. Kynurenines: Tryptophan’s metabolites in exercise, inflammation, and mental health. Science. 2017;357(6349):eaaf9794. DOI:: 10.1126/science.aaf9794 PMID:: 28751584 Published:: August 3, 2017 Study Design:: Review article Key Findings::
- Kynurenine pathway integrates immune, metabolic, and neurological signaling across organs
- Peripheral inflammation drives kynurenine accumulation in brain
- Exercise activates kynurenine clearance in skeletal muscle
- Different metabolites have opposing effects: KYNA (neuroprotective, NMDA antagonist), QA (neurotoxic, NMDA agonist)
- Interorgan cross-talk via kynurenine metabolites connects exercise to mental healthConclusion:: Kynurenine pathway serves as critical communication axis between periphery and CNS, mediating effects of inflammation and exercise on brain function. Limitations:: Review article; limited primary data on ME/CFS specifically.
11 Schwarcz et al. 2012 — Kynurenines in Brain Physiology and Pathology (0.95)
Full Citation:: Schwarcz R, Bruno JP, Muchowski PJ, Wu HQ. Kynurenines in the mammalian brain: when physiology meets pathology. Nat Rev Neurosci. 2012 Jul;13(7):465-477. DOI:: 10.1038/nrn3257 PMID:: 22678511 Published:: July 2012 Study Design:: Review article Key Findings::
- Tryptophan degraded to neuroactive compounds via kynurenine pathway (KYNA, 3-HK, QA)
- Pathway tightly controlled by immune system via IDO activation
- Dysregulation causes hyper/hypofunction of active metabolites
- Associated with neurodegenerative and psychiatric disorders
- QA is NMDA receptor agonist causing excitotoxicity; KYNA is NMDA antagonistConclusion:: Kynurenine pathway dysregulation underlies multiple neurological disorders; therapeutic targeting of specific metabolites may restore balance. Limitations:: Review article; limited primary data on ME/CFS specifically.
12 Che et al. 2025 — Innate Immunity and Kynurenine Pathway in ME/CFS (0.65)
Full Citation:: Che X, Ranjan A, Guo C, Zhang K, Goldsmith R, Levine S, Moneghetti KJ, Zhai Y, Ge L, Mishra N, Hornig M, Bateman L, Klimas NG, Montoya JG, Peterson DL, Klein SL, Fiehn O, Komaroff AL, Lipkin WI. Heightened innate immunity may trigger chronic inflammation, fatigue and post-exertional malaise in ME/CFS. NPJ Metabolic Health and Disease. 2025 Sep 3;3(1):34. DOI:: 10.1038/s44324-025-00079-w PMID:: 40903540 Published:: September 3, 2025 Study Design:: Multi-omics case-control study Sample Size:: Not specified in abstract Key Findings::
- Multi-omics analysis of ME/CFS patients before/after exercise
- Exaggerated innate immune response after microbial antigen exposure
- Impaired energy production (citric acid cycle, β-oxidation, urea cycle)
- Dysregulation of tryptophan-serotonin-kynurenine pathways
- Abnormalities worsened after exercise, correlated with symptom intensityConclusion:: Heightened innate immunity triggers metabolic abnormalities that may underlie ME/CFS symptoms, particularly PEM. Limitations:: Abstract-only access; sample size not specified; single-cohort study.
13 Chojnacki et al. 2026 — Probiotic Modulates Kynurenine Pathway in CFS (0.60)
Full Citation:: Chojnacki C, Mȩdrek-Socha M, Chojnacki J, Gąsiorowska A, Walecka-Kapica E, Bijak M, Przybylowska-Sygut K, Poplawski T. Multi-Strain Probiotic Improves Tryptophan Metabolism and Symptoms in Chronic Fatigue Syndrome Patients with Co-Occurring Irritable Bowel Syndrome: An Open-Label Pilot Study. Nutrients. 2026 Jan 5;18(1):174. DOI:: 10.3390/nu18010174 PMID:: 41515290 Published:: January 5, 2026 Study Design:: Open-label pilot study Sample Size:: 40 female CFS+IBS patients Key Findings::
- 40 female CFS+IBS patients with dysbiosis treated with CDS22 probiotic (450B CFU/day, 12 weeks)
- Baseline: elevated bacterial proteolytic markers (3-IS), low tryptophan, high QA, low KYNA
- Post-treatment: fatigue scores declined 40.3%, 97.5% reached remission threshold
- 3-IS decreased to healthy levels, KYNA/QA ratio increased 45%
- Increased tryptophan availability correlated with symptom reductionConclusion:: Probiotic modulates gut-kynurenine axis, reduces neurotoxic QA, increases neuroprotective KYNA, improving CFS symptoms. Limitations:: Open-label design (no placebo control); female-only cohort; single-center study.
14 Yan et al. 2026 — Dendrobium officinale Modulates Tryptophan Metabolism in Fatigue (0.45)
Full Citation:: Yan M, Shi M, Li C, Yu B, Zhou H, Su J, Yu J, Lv G, Chen S. Effects of Dendrobium officinale on chronic fatigue in rats: Modulation of tryptophan metabolism. J Ethnopharmacol. 2026 Jun 28;365:121527. DOI:: 10.1016/j.jep.2026.121527 PMID:: 41861923 Published:: June 28, 2026 Study Design:: Animal study (rat model) Sample Size:: Not specified in abstract Key Findings::
- Chronic fatigue rat model via complex lifestyle stressors
- Dendrobium officinale improved endurance and reduced depression-like behavior
- Fatigue model showed inhibited kynurenine pathway
- Treatment restored kynurenine pathway, upregulated TDO2, KMO, KAT1
- Increased both gut-derived indole metabolites and kynurenine metabolites (3-HAA, QA, PA, XA)Conclusion:: Dendrobium officinale ameliorates chronic fatigue by modulating tryptophan-kynurenine metabolism via gut microbiota. Limitations:: Animal model; traditional medicine focus; single study; mechanism extrapolation to humans.
15 Zhang et al. 2026 — Mitochondrial Genetics in Chronic Fatigue (0.50)
Full Citation:: Zhang Z, Xiao Z, Mei H, Qi J, Gao Y, Zhang Y, Li F. Mitochondria-Related Genome-Wide Mendelian Randomization Identifies Putatively Genes for Chronic Fatigue. Mol Neurobiol. 2026 Apr 29;63(1):596. DOI:: 10.1007/s12035-026-05896-8 PMID:: 42053855 Published:: April 29, 2026 Study Design:: Mendelian randomization + animal validation Sample Size:: Blood eQTL (n=31,684), fatigue GWAS (n=449,019) Key Findings::
- Mendelian randomization using blood eQTL and fatigue GWAS
- Identified mitochondrial-related genes AKAP10 and MTHFD1L with causal links to chronic fatigue
- TSMR confirmed causal relationships
- Fatigue model rats showed upregulated Akap10 and Mthfd1l in hippocampus and quadriceps
- Molecular docking revealed strong binding with repurposed drugs (irinotecan, digoxin)Conclusion:: Mitochondrial genes AKAP10 and MTHFD1L are causally linked to chronic fatigue; potential therapeutic targets. Limitations:: General chronic fatigue, not ME/CFS-specific; animal validation limited.
16 El-Baga et al. 2026 — EAAT2 and Glutamate Excitotoxicity (0.40)
Full Citation:: El-Baga SE, Hassan MH, Awadalla EA, Abd El-Kader AEM. Crocin Mitigates Glutamate Excitotoxicity and Tau Hyperphosphorylation by Modulating EAAT2 and Akt/Tau Pathway in a Scopolamine-induced Rat Model of Alzheimer’s Disease. Neurochem Res. 2026 Mar 5;51(2):100. DOI:: 10.1007/s11064-026-04692-z PMID:: 41784832 Published:: March 5, 2026 Study Design:: Animal study (rat model) Sample Size:: Not specified in abstract Key Findings::
- Alzheimer's rat model: scopolamine elevated glutamate, NMDAR, p-tau; reduced EAAT2
- Crocin treatment restored neurotransmitter balance, downregulated NMDAR, upregulated EAAT2
- Increased p-Akt expression, reduced tau phosphorylation
- Histological analysis confirmed hippocampal neuron recoveryConclusion:: EAAT2 downregulation causes glutamate accumulation and excitotoxicity; crocin restores EAAT2 function and mitigates damage. Limitations:: Alzheimer’s model, not ME/CFS; animal study; extrapolation to ME/CFS required.
17 Manisha et al. 2026 — EAAT2 Activator Attenuates Excitotoxicity (0.40)
Full Citation:: Manisha C, Ganguly A, Palathoti N, Selvaraj J, Kumar BRP, Clement JP, Jeyabalan JB, Justin A. Computational Based Identified EAAT2 Transporter Activator Attenuates Amyloid-β Induced Excitotoxicity in Primary Neuronal-Astroglial Mixed Culture. Chem Biol Drug Des. 2026 Jan;107(1):e70232. DOI:: 10.1111/cbdd.70232 PMID:: 41482937 Published:: January 2026 Study Design:: In vitro study (neuronal-astroglial mixed culture) Sample Size:: Cell culture model Key Findings::
- Aβ deposition induces oxidative alterations in astrocytic EAAT2
- Impaired EAAT2 causes elevated extracellular glutamate and excitotoxicity
- Identified allosteric EAAT2 modulators (PTID, NDHP)
- Compounds enhanced EAAT2 expression/function, reduced glutamate, improved neuron survivalConclusion:: EAAT2 impairment underlies Aβ-induced excitotoxicity; allosteric EAAT2 activators are promising therapeutic candidates. Limitations:: In vitro study; Alzheimer’s focus; extrapolation to ME/CFS required.
18 Zhang et al. 2026 — PirB-EAAT Pathway in Excitotoxicity (0.40)
Full Citation:: Zhang X, Zhao Y, Chen X, Shen W, Huang L, Tan T. Suppression of Astrocytic PirB Alleviates Aβ-Induced Excitotoxicity and Cognitive Deficits via EAAT Expression. Glia. 2026 Feb;74(2):e70130. DOI:: 10.1002/glia.70130 PMID:: 41427574 Published:: February 2026 Study Design:: Animal study (mouse model) Sample Size:: Not specified in abstract Key Findings::
- PirB inhibition increased EAAT1 and EAAT2 expression, activated mTOR signaling
- Elevated astrocytic glutamate levels, decreased intracellular calcium, reduced neuronal apoptosis
- PirB cKO mice showed improved cognition, higher EAAT expression, reduced apoptosis
- PirB-mTOR-EAAT pathway identified as therapeutic targetConclusion:: PirB regulates EAAT expression and glutamate homeostasis; PirB inhibition alleviates excitotoxicity via EAAT upregulation. Limitations:: Alzheimer’s model, not ME/CFS; animal study; extrapolation to ME/CFS required.
19 Rothstein et al. 1996 — EAAT2 Knockout Reveals Astroglial Transport in Excitotoxicity (0.95)
Full Citation:: Rothstein JD, Dykes-Hoberg M, Pardo CA, Bristol LA, Jin L, Kuncl RW, Kanai Y, Hediger MA, Wang Y, Schieke JP, Welty DF. Knockout of glutamate transporters reveals a major role for astroglial transport in excitotoxicity and clearance of glutamate. Neuron. 1996 Oct;16(3):675-686. DOI:: 10.1016/s0896-6273(00)80096-9 PMID:: 8915429 Published:: October 1996 Study Design:: Animal study (knockout mice) Sample Size:: Not specified in abstract Key Findings::
- GLT-1 (EAAT2) knockout mice developed lethal neurodegeneration
- Absence of GLT-1 caused elevated extracellular glutamate, excitotoxic neuronal death
- Astrocytic glutamate transport is primary mechanism for clearing glutamate from synaptic cleft
- Na+/K+ gradient essential for EAAT2 function; ATP depletion impairs glutamate clearanceConclusion:: EAAT2 is critical for glutamate homeostasis; its impairment causes excitotoxicity independent of increased glutamate release. Limitations:: Animal model; findings extrapolated to human neurological disorders including ME/CFS.