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Majdi A, Asamoah B, Mc Laughlin M. Understanding Neuromodulation Pathways in tDCS: Brain Stem Recordings in Rat During Trigeminal Nerve Direct Current Stimulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.14.557723. [PMID: 37745349 PMCID: PMC10515934 DOI: 10.1101/2023.09.14.557723] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Background Recent evidence suggests that transcranial direct current stimulation (tDCS) indirectly influences brain activity through cranial nerve pathways, particularly the trigeminal nerve. However, the electrophysiological effects of direct current (DC) stimulation on the trigeminal nerve (DC-TNS) and its impact on trigeminal nuclei remain unknown. These nuclei exert control over brainstem centers regulating neurotransmitter release, such as serotonin and norepinephrine, potentially affecting global brain activity. Objectives To investigate how DC-TNS impacts neuronal activity in the principal sensory nucleus (NVsnpr) and the mesencephalic nucleus of the trigeminal nerve (MeV). Methods Twenty male Sprague Dawley rats (n=10 each nucleus) were anesthetized with urethane. DC stimulation, ranging from 0.5 to 3 mA, targeted the trigeminal nerve's marginal branch. Simultaneously, single-unit electrophysiological recordings were obtained using a 32-channel silicon probe, comprising three one-minute intervals: pre-stimulation, DC stimulation, and post-stimulation. Xylocaine was administered to block the trigeminal nerve as a control. Results DC-TNS significantly increased neuronal spiking activity in both NVsnpr and MeV, returning to baseline during the post-stimulation phase. When the trigeminal nerve was blocked with xylocaine, the robust 3 mA trigeminal nerve DC stimulation failed to induce increased spiking activity in the trigeminal nuclei. Conclusion Our results offer initial empirical support for trigeminal nuclei activity modulation via DC-TNS. This discovery supports the hypothesis that cranial nerve pathways may play a pivotal role in mediating tDCS effects, setting the stage for further exploration into the complex interplay between peripheral nerves and neural modulation techniques. Highlights Direct current stimulation of the trigeminal nerve (DC-TNS) modulates neural activity in rat NVsnpr and MeV.Xylocaine administration reversibly blocks the DC-TNS effect on neural responses.Trigeminal nerve stimulation should be considered a possible mechanism of action of tDCS.
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Demiral ŞB, Kure Liu C, Benveniste H, Tomasi D, Volkow ND. Activation of brain arousal networks coincident with eye blinks during resting state. Cereb Cortex 2023:6991186. [PMID: 36653022 DOI: 10.1093/cercor/bhad001] [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: 05/09/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 01/20/2023] Open
Abstract
Eye-blinking has been implicated in arousal and attention. Here we test the hypothesis that blinking-moments represent arousal surges associated with activation of the ascending arousal network (AAN) and its thalamic projections. For this purpose, we explored the temporal relationship between eye-blinks and fMRI BOLD activity in AAN and thalamic nuclei, as well as whole brain cluster corrected activations during eyes-open, resting-state fMRI scanning. We show that BOLD activations in the AAN nuclei peaked prior to the eye blinks and in thalamic nuclei peaked prior to and during the blink, consistent with the role of eye blinking in arousal surges. Additionally, we showed visual cortex peak activation prior to the eye blinks, providing further evidence of the visual cortex's role in arousal, and document cerebellar peak activation post eye blinks, which might reflect downstream engagement from arousal surges.
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Affiliation(s)
- Şükrü Barış Demiral
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda 20892, MD, USA
| | - Christopher Kure Liu
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda 20892, MD, USA
| | - Helene Benveniste
- Department of Anesthesiology, Yale University, New Haven, CT 06510, USA
| | - Dardo Tomasi
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda 20892, MD, USA
| | - Nora D Volkow
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda 20892, MD, USA.,National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA
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Coupling between Trigeminal-Induced Asymmetries in Locus Coeruleus Activity and Cognitive Performance. Symmetry (Basel) 2021. [DOI: 10.3390/sym13091676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In humans, the asymmetry in the masseter electromyographic (EMG) activity during clenching is positively correlated with the degree of pupil size asymmetry (anisocoria) at rest. Anisocoria reveals an asymmetry in LC activity, which may lead to an imbalance in cortical excitability, detrimental to performance. Hereby, we investigated, in individual subjects, the possibility that occlusal correction, which decreases EMG asymmetry, improves performance by balancing LC activity. Cognitive performance, task-related mydriasis, and pupil size at rest were modified by changing the occlusal condition. Occlusal-related changes in performance and mydriasis were negatively correlated with anisocoria changes in only 12/20 subjects. Within this population, spontaneous fluctuations in mydriasis and anisocoria also appeared negatively coupled. Occlusal-related changes in performance and mydriasis were negatively correlated with those in average pupil size (a proxy of average LC activity) in 19/20 subjects. The strongest association was observed for the pupil changes occurring on the side with higher EMG activity during clenching. These findings indicate that the effects of occlusal conditions on cognitive performance were coupled to changes in the asymmetry of LC activity in about half of the subjects, while they were related to changes in the average tonic LC activity in virtually all of them.
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Brighenti T, Malerba M, Cozzini T, Marcon A, Vedovi E, Nocini R, Formentini D, Pedrotti E, Nocini PF. Effects of oral function on pupil response: a new view on bruxism pathophysiology. Minerva Dent Oral Sci 2021; 70:233-238. [PMID: 33908745 DOI: 10.23736/s2724-6329.21.04506-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND There are increasing evidences of the influence of the oropharyngeal stimulations on the autonomic nervous system and an easy approach to evaluate the balance between parasympathetic and sympathetic system is the measurement of the pupil diameter. The aim of this analytic observational study is to define the effects of clenching and swallowing on pupil diameter, and how an oral appliance can affect the outcome of these tasks, to establish their influence on the sympathetic-parasympathetic balance. METHODS We measured the pupil diameter in 30 healthy subjects during clenching and swallowing, both with and without oral appliance. We compared the results with the mandibular rest position. The respective positions with and without oral appliance were also compared. RESULTS Pupillometry showed a mydriatic effect of swallowing (rest=6.94 mm, swallowing=7.26 mm, p=0.04) and oral appliance, more relevant in scotopic conditions. On the contrary, clenching seemed to enhance miosis, especially in intense brightness condition (rest=3.95 mm, clenching=3.83 mm, p=0.02). CONCLUSIONS Swallowing and oral appliance facilitate the sympathetic system, while clenching activates the parasympathetic branch. We argue that probably the locus coeruleus is the main hub. These results could have practical implications in bruxism physiology, because it could be an attempt to counteract the activation of the sympathetic system.
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Affiliation(s)
- Tommaso Brighenti
- Department of Neuroscience, Biomedicine and Movement Sciences, Eye Clinic, University of Verona, Verona, Italy -
| | - Mauro Malerba
- School of Dentistry, Department of Surgery, Dentistry, Paediatrics and Gynaecology (DIPSCOMI), University of Verona, Verona, Italy
| | - Tiziano Cozzini
- Department of Neuroscience, Biomedicine and Movement Sciences, Eye Clinic, University of Verona, Verona, Italy
| | - Alessandro Marcon
- Unit of Epidemiology and Medical Statistics, Department of Diagnostics and Public Health, University of Verona, Verona, Italy
| | - Ermes Vedovi
- UOC Rehabilitation, Department of Neuroscience, Verona University Hospital, Verona, Italy
| | - Riccardo Nocini
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospital of Verona, Verona, Italy
| | - Daniele Formentini
- School of Dentistry, Department of Surgery, Dentistry, Paediatrics and Gynaecology (DIPSCOMI), University of Verona, Verona, Italy
| | - Emilio Pedrotti
- Department of Neuroscience, Biomedicine and Movement Sciences, Eye Clinic, University of Verona, Verona, Italy
| | - Pier Francesco Nocini
- School of Dentistry, Department of Surgery, Dentistry, Paediatrics and Gynaecology (DIPSCOMI), University of Verona, Verona, Italy
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Ginatempo F, De Carli F, Todesco S, Mercante B, Sechi GP, Deriu F. Effects of acute trigeminal nerve stimulation on rest EEG activity in healthy adults. Exp Brain Res 2018; 236:2839-2845. [PMID: 30039458 DOI: 10.1007/s00221-018-5338-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 07/18/2018] [Indexed: 10/28/2022]
Abstract
Trigeminal nerve stimulation (TNS) is a non-invasive neuromodulation method which is increasingly used for its beneficial effects on symptoms of several neuropsychiatric disorders such as drug-resistant epilepsy. Sites and mechanisms of its action are still unknown. The present study was aimed at investigating the physiological effects of acute TNS on rest electroencephalographic (EEG) activity. EEG was recorded with a 19-channel EEG system from 18 healthy adults who underwent 20 min of sham- and real-TNS (cycles of 30 s ON and 30 s OFF) in two separate sessions. EEG was continuously acquired in the 10-min preceding TNS, during TNS in the "OFF" period and throughout 10 min after TNS. Mean frequency, total power over the 0.5-48 Hz frequency range and absolute power for delta, theta, alpha, beta and gamma bands were analyzed by a discrete Fast Fourier Transform algorithm. Interhemispheric and intrahemispheric coherences were also analyzed for each band at different time points. Intra- and interhemispheric coherences were significantly reduced for the beta frequencies only during real-TNS (p = 0.002 and p = 0.006, respectively). No TNS effect on the power spectra of any band was detected. A trend of increase in the mean EEG frequency total power during real-TNS (p = 0.03) and of decrease in interhemispheric gamma coherence after real-TNS (p = 0.01) was observed. Acute TNS may induce a spatially diffuse desynchronization of fast EEG rhythms in healthy adults, this desynchronization may underpin the antiepileptic effect of TNS described by clinical studies.
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Affiliation(s)
- Francesca Ginatempo
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy
| | - Fabrizio De Carli
- Genoa Section, Institute of Bioimaging and Molecular Physiology, National Research Council, Genoa, Italy
| | - Sara Todesco
- Neurology Unit, «A. Segni» Hospital, ASL n. 1, Sassari, Italy
| | - Beniamina Mercante
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy
| | - Gian Pietro Sechi
- Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy
| | - Franca Deriu
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy.
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De Cicco V, Tramonti Fantozzi MP, Cataldo E, Barresi M, Bruschini L, Faraguna U, Manzoni D. Trigeminal, Visceral and Vestibular Inputs May Improve Cognitive Functions by Acting through the Locus Coeruleus and the Ascending Reticular Activating System: A New Hypothesis. Front Neuroanat 2018; 11:130. [PMID: 29358907 PMCID: PMC5766640 DOI: 10.3389/fnana.2017.00130] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/15/2017] [Indexed: 12/25/2022] Open
Abstract
It is known that sensory signals sustain the background discharge of the ascending reticular activating system (ARAS) which includes the noradrenergic locus coeruleus (LC) neurons and controls the level of attention and alertness. Moreover, LC neurons influence brain metabolic activity, gene expression and brain inflammatory processes. As a consequence of the sensory control of ARAS/LC, stimulation of a sensory channel may potential influence neuronal activity and trophic state all over the brain, supporting cognitive functions and exerting a neuroprotective action. On the other hand, an imbalance of the same input on the two sides may lead to an asymmetric hemispheric excitability, leading to an impairment in cognitive functions. Among the inputs that may drive LC neurons and ARAS, those arising from the trigeminal region, from visceral organs and, possibly, from the vestibular system seem to be particularly relevant in regulating their activity. The trigeminal, visceral and vestibular control of ARAS/LC activity may explain why these input signals: (1) affect sensorimotor and cognitive functions which are not directly related to their specific informational content; and (2) are effective in relieving the symptoms of some brain pathologies, thus prompting peripheral activation of these input systems as a complementary approach for the treatment of cognitive impairments and neurodegenerative disorders.
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Affiliation(s)
- Vincenzo De Cicco
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Maria P Tramonti Fantozzi
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | | | - Massimo Barresi
- Institut des Maladie Neurodégénératives, University of Bordeaux, Bordeaux, France
| | - Luca Bruschini
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Ugo Faraguna
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy.,Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Diego Manzoni
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
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Mercante B, Pilurzi G, Ginatempo F, Manca A, Follesa P, Tolu E, Deriu F. Trigeminal nerve stimulation modulates brainstem more than cortical excitability in healthy humans. Exp Brain Res 2015; 233:3301-11. [DOI: 10.1007/s00221-015-4398-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 07/27/2015] [Indexed: 12/30/2022]
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Zorba OÜ, Kirbaş S, Uzun H, Önem K, Çetinkaya M, Rifaioğlu MM. Is There a Relation between Reticular Formation and Storage Symptoms in Men. Low Urin Tract Symptoms 2014; 6:46-51. [PMID: 26663500 DOI: 10.1111/luts.12020] [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: 12/17/2012] [Revised: 02/07/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To reveal brainstem originated pathology in men with different types of lower urinary tract symptoms blink reflex latency times were assessed. METHODS A total of 32 men, 16 with storage and 16 with voiding symptoms, were enrolled in the study. Blink reflex latency times were analyzed through electrical stimulation of the supraorbital nerve. Two responses in the orbicularis oculi muscle were recorded: the latency times for the early ipsilateral response, R1, and the late bilateral responses, R2. RESULTS The mean ages of the patients with storage and voiding symptoms were 57.31 ± 6.87 and 58.06 ± 6.29 years, respectively. The R2 latency times were significantly longer in men with storage symptoms. However, the R1 latency times were similar for the two groups. CONCLUSION Late blink latency times were long only in patients who had storage symptoms. An oligosynaptic path through the trigeminal nuclei, which includes one or two interneurons, is responsible for early response; however, late response is relayed through a polysynaptic path, including neurons in the reticular formation. It has also been shown that stimulation of the pontine reticular formation inhibits the micturition contraction. In some patients, storage symptoms may result from pathology that originates with the reticular formation and this pathology may lead to increases in late blink latency times. Additional studies are needed on other reflexes that are mediated through reticular formation, in order to show the possible dysfunction of the reticular formation in men with storage symptoms.
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Affiliation(s)
- Orhan Ü Zorba
- Department of Urology, Recep Tayyip Erdogan University, Rize, Turkey
| | - Serkan Kirbaş
- Department of Neurology, Recep Tayyip Erdogan University, Rize, Turkey
| | - Hakkı Uzun
- Department of Urology, Recep Tayyip Erdogan University, Rize, Turkey
| | - Kadir Önem
- Department of Urology, Ondokuz Mayis University, Samsun, Turkey
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Bertram C, Dahan L, Boorman LW, Harris S, Vautrelle N, Leriche M, Redgrave P, Overton PG. Cortical regulation of dopaminergic neurons: role of the midbrain superior colliculus. J Neurophysiol 2013; 111:755-67. [PMID: 24225541 PMCID: PMC3921396 DOI: 10.1152/jn.00329.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dopaminergic (DA) neurons respond to stimuli in a wide range of modalities, although the origin of the afferent sensory signals has only recently begun to emerge. In the case of vision, an important source of short-latency sensory information seems to be the midbrain superior colliculus (SC). However, longer-latency responses have been identified that are less compatible with the primitive perceptual capacities of the colliculus. Rather, they seem more in keeping with the processing capabilities of the cortex. Given that there are robust projections from the cortex to the SC, we examined whether cortical information could reach DA neurons via a relay in the colliculus. The somatosensory barrel cortex was stimulated electrically in the anesthetized rat with either single pulses or pulse trains. Although single pulses produced small phasic activations in the colliculus, they did not elicit responses in the majority of DA neurons. However, after disinhibitory intracollicular injections of the GABAA antagonist bicuculline, collicular responses were substantially enhanced and previously unresponsive DA neurons now exhibited phasic excitations or inhibitions. Pulse trains applied to the cortex led to phasic changes (excitations to inhibitions) in the activity of DA neurons at baseline. These were blocked or attenuated by intracollicular administration of the GABAA agonist muscimol. Taken together, the results indicate that the cortex can communicate with DA neurons via a relay in the SC. As a consequence, DA neuronal activity reflecting the unexpected occurrence of salient events and that signaling more complex stimulus properties may have a common origin.
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Affiliation(s)
- C Bertram
- Department of Psychology, University of Sheffield, Western Bank, Sheffield, United Kingdom; and
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Zorba OÜ, Kırbaş S, Uzun H, Cetinkaya M, Önem K, Rifaioğlu MM. Overactive bladder and pontine reticular formation. Urol Int 2013; 91:417-22. [PMID: 24296362 DOI: 10.1159/000350940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 03/23/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND The etiology of overactive bladder (OAB) remains unclear. Observed neurogenic factors in the literature are limited to suprapontine or spinal pathologies. The blink reflex is a useful tool in the evaluation of brainstem functions. Blink reflex latency times were evaluated in order to reveal pathology in the brainstem. METHODS A total of 60 women, 30 patients with idiopathic OAB and 30 healthy controls, were enrolled in the study. Blink reflex latency times were analyzed by electrical stimulation of the supraorbital nerve. Two responses in the orbicularis oculi muscle, early ipsilateral response (R1) and late bilateral response (R2) latency times, were recorded. RESULTS Mean ages of the patients and controls were 51.9 ± 5.3 and 49.2 ± 6.2 years, respectively. R2 latency times were significantly higher in patients than in controls. However, R1 latency times were similar between the two groups. CONCLUSIONS The results of the study suggest a significant relation between late blink latency times and OAB. An oligosynaptic path via the trigeminal nuclei is responsible for R1; however, R2 response is relayed through the reticular formation. Stimulation of pontine reticular formation inhibits micturition contraction. In some patients, idiopathic OAB may result from reticular formation-originated pathology. Additional studies on other reticular formation-mediated reflexes are needed to reveal possible dysfunction of reticular formation.
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Affiliation(s)
- Orhan Ünal Zorba
- Department Urology, Faculty of Medicine, Recep Tayyip Erdoğan University, Rize, Turkey
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