Journal of neurophysiology最新文献

{"title":"Theta-burst stimulation over primary somatosensory cortex modulates the tactile acuity of the tongue.","authors":"Ding-Lan Tang, Mark Tommerdahl, Caroline A Niziolek, Benjamin Parrell","doi":"10.1152/jn.00556.2024","DOIUrl":"10.1152/jn.00556.2024","url":null,"abstract":"<p><p>Emerging studies in humans have established the modulatory effects of repetitive transcranial magnetic stimulation (rTMS) over primary somatosensory cortex (S1) on somatosensory cortex activity and perception. However, to date, research in this area has primarily focused on the hand and fingers, leaving a gap in our understanding of the modulatory effects of rTMS on somatosensory perception of the orofacial system and speech articulators. The present study aimed to examine the effects of different types of theta-burst stimulation (TBS)-continuous TBS (cTBS), intermittent TBS (iTBS), or sham-over the tongue representation of left S1 on tactile acuity of the tongue. In a repeated-measures design, 15 volunteers participated in four separate sessions, where cTBS, iTBS, sham, or no stimulation was applied over the tongue representation of left S1. Effects of TBS were measured on both temporal and spatial perceptual acuity of the tongue using a custom vibrotactile stimulator. Results showed that cTBS significantly impaired spatial amplitude threshold at the time window of 16-30 min after stimulation, whereas iTBS improved it at the same time window. The effect of iTBS, however, was smaller than cTBS. In contrast, neither cTBS nor iTBS had any effect on the temporal discrimination threshold. The current study establishes the validity of using TBS to modulate somatosensory perception of the orofacial system. Directly modifying somatosensation in the orofacial system has the potential to benefit clinical populations with abnormal tactile acuity, improve our understanding of the role of sensory systems in speech production, and enhance speech motor learning and rehabilitation.<b>NEW & NOTEWORTHY</b> The current study examines the effects of different types of theta-burst stimulation (TBS) [continuous TBS (cTBS), intermittent TBS (iTBS), sham] over the tongue representation of left primary somatosensory cortex (S1). Results show that the spatial acuity of the tongue can be impaired or improved by cTBS or iTBS, respectively. Directly modifying somatosensation in the orofacial system can benefit clinical populations with abnormal tactile acuity, advance our understanding of sensory systems in speech production, and improve speech motor learning and rehabilitation.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1341-1349"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143730487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Higher hyperpolarization-activated current in a subpopulation of interneurons in stratum oriens of area CA1 in the hippocampus of fragile X mice.","authors":"Lauren T Hewitt, Alyssa M Marron, Darrin H Brager","doi":"10.1152/jn.00510.2024","DOIUrl":"https://doi.org/10.1152/jn.00510.2024","url":null,"abstract":"<p><p>Fragile X syndrome is the most common inherited form of intellectual disability and the leading monogenetic cause of autism. Studies in mouse models of autism spectrum disorders, including the <i>Fmr1</i> knockout (FX) mouse, suggest that abnormal inhibition in hippocampal circuits contributes to behavioral phenotypes. In FX mice, changes in multiple voltage-gated ion channels occur in excitatory pyramidal neurons of the hippocampus. Whether there are also changes in the intrinsic properties of hippocampal inhibitory interneurons, however, remains largely unknown. We made whole cell current clamp recordings from both fast-spiking (FS) and low threshold spiking (LTS) interneurons in the stratum oriens region of the hippocampus. We found that LTS, but not FS, interneurons in FX mice had lower input resistance and action potential firing compared with the wild type. When we subdivided LTS interneurons into low-threshold high hyperpolarization-activated current (<i>I</i>_h) (LTH) and putative oreins-lacunosum moleculare (OLM) cells (Hewitt et al. <i>Physiol Rep</i> 9: e14848, 2021), we found that it was the LTH subgroup that had significantly lower input resistance in FX mice. The difference in input resistance between wild-type and FX LTH interneurons was absent in the presence of the h-channel blocker ZD7288, suggesting a greater contribution of <i>I</i>_h in FX LTH interneurons. Voltage clamp recordings found that indeed, <i>I</i>_h was significantly higher in FX LTH interneurons compared with wild type. Our results suggest that altered inhibition in the hippocampus of FX mice may be due in part to changes in the intrinsic excitability of LTH inhibitory interneurons.<b>NEW & NOTEWORTHY</b> In this paper, we use physiological and biochemical approaches to investigate the intrinsic excitability of inhibitory interneurons in hippocampal area CA1 of the fragile X mouse. We found that higher <i>I</i>_h lowers the intrinsic excitability of one specific type of interneuron. This study highlights how changes to voltage-gated ion channels in specific neuronal populations may contribute to the altered excitatory/inhibitory balance in fragile X syndrome.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":"133 5","pages":"1558-1571"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143997180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visually evoked activity and variable modulation of auditory responses in the macaque inferior colliculus.","authors":"Meredith N Schmehl, Jesse L Herche, Jennifer M Groh","doi":"10.1152/jn.00529.2024","DOIUrl":"10.1152/jn.00529.2024","url":null,"abstract":"<p><p>How multisensory cues affect processing in early sensory brain areas is not well understood. The inferior colliculus (IC) is an early auditory structure that is visually responsive (Porter KK, Metzger RR, Groh JM. <i>Proc Natl Acad Sci USA</i> 104: 17855-17860, 2007; Bulkin DA, Groh JM. <i>Front Neural Circuits</i> 6: 61, 2012; Bulkin DA, Groh JM. <i>J Neurophysiol</i> 107: 785-795, 2012), but little is known about how visual signals affect the IC's auditory representation. We explored how visual cues affect both spiking and local field potential (LFP) activity in the IC of two monkeys performing a task involving saccades to auditory, visual, or combined audiovisual stimuli. We confirm that LFPs are sensitive to the onset of fixation lights and the onset of visual targets presented during steady fixation. The LFP waveforms evoked by combined audiovisual stimuli differed from those evoked by sounds alone. In single-unit spiking activity, responses were weak when visual stimuli were presented alone, but visual stimuli could modulate the activity evoked by sounds in a stronger way. Such modulations could involve either increases or decreases in activity, and whether increases or decreases were observed was variable and not obviously correlated with the responses evoked by visual or auditory stimuli alone. These findings indicate that visual stimuli shape the IC's auditory representation in flexible ways that differ from those observed previously in multisensory areas.<b>NEW & NOTEWORTHY</b> We find that the inferior colliculus, a primarily auditory brain area, displays distinct population-level responses to visual stimuli. We also find that visual cues can influence the auditory responses of individual neurons. Together, the results provide insight into how relatively early sensory areas may play a role in combining multiple sensory modalities to refine the perception of complex environments.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1456-1467"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12131782/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cortical alpha rhythms interpolate occluded motion from natural scene context.","authors":"Lu-Chun Yeh, Max Bardelang, Daniel Kaiser","doi":"10.1152/jn.00048.2025","DOIUrl":"https://doi.org/10.1152/jn.00048.2025","url":null,"abstract":"<p><p>Tracking objects as they dynamically move in and out of sight is critical for parsing our everchanging real-world surroundings. Here, we explored how the interpolation of occluded object motion in natural scenes is mediated by top-down information flows expressed in cortical alpha rhythms. We recorded EEG while participants viewed videos of a person walking across a scene. We then used multivariate decoding on alpha-band responses to decode the direction of movement across the scene. In trials where the person was temporarily occluded, alpha dynamics interpolated the person's predicted movement. Critically, they did so in a context-dependent manner: When the scene context required the person to stop in front of an obstacle, alpha dynamics tracked the termination of motion during occlusion. As these effects were obtained with an orthogonal task at fixation, we conclude that alpha rhythms automatically interpolate occluded motion based on the contextual cues from the surrounding environment.<b>NEW & NOTEWORTHY</b> Inferring how objects continue to move during occlusion requires contextual cues from the surrounding environment. Such contextual information is incorporated via neural feedback linked to cortical alpha oscillations. Here, we demonstrate that alpha dynamics track the predicted movement of a person during occlusion, depending on scene context: Alpha oscillations not only track how the person moves when their path is unobstructed but also when they need to stop because of obstacles blocking their way.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":"133 5","pages":"1497-1502"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intrinsic voltage fluctuations reveal a form of phase-amplitude coupling in electrosensory pyramidal neurons.","authors":"Alexandre Melanson, Samuel Fontaine, Grégoire Richard, Jérémy Guy Belliveau","doi":"10.1152/jn.00444.2024","DOIUrl":"10.1152/jn.00444.2024","url":null,"abstract":"<p><p>The stochastic flickering of ion channels is known to cause ongoing membrane potential fluctuations in neurons. This channel noise is often considered negligible when compared with synaptic noise, yet it can shape the integrative properties of neurons. Here, in vitro recordings of electrosensory pyramidal neurons under synaptic blockade are characterized and shown to contain a nontrivial repertoire of dynamical features. Our analyses reveal an intrinsic noise structure that is much richer than what could be expected based on previous studies: we identify rapid, small-amplitude, shot noise-like events and we quantify how their rate and amplitude are modulated by slower, large-amplitude fluctuations. This cross-relation is evidence that, at the single-neuron level, membrane potential dynamics can exhibit a form of phase-amplitude coupling. We also investigate the appearance of fast, intermittent subthreshold oscillations and conclude that they are manifestation of stochastic linear dynamics, possibly with time-varying parameters. Our results, collectively, highlight that neurons can spontaneously display rich intrinsic behavior, which is likely to impact how they process synaptic input.<b>NEW & NOTEWORTHY</b> How do neurons behave in the absence of synaptic input? Can their intrinsic activity convey important information about how they function? Here, we provide evidence that the structure of intrinsic voltage noise in pyramidal neurons contains several nontrivial components, contrary to what is usually assumed. We show, for the first time, that a form of phase-amplitude coupling can exist in the spontaneous electrical activity of single neurons.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1392-1403"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rebound electroencephalographic responses to nitrous oxide exposure in men.","authors":"Petra Valtonen, Stanislav Rozov, Iina Annala, Kaija Järventausta, Narayan Puthanmadam Subramaniyam, Mirja Tenhunen, Jari Hyttinen, Arvi Yli-Hankala, Tomi Rantamäki, Maija-Liisa Kalliomäki","doi":"10.1152/jn.00275.2024","DOIUrl":"https://doi.org/10.1152/jn.00275.2024","url":null,"abstract":"<p><p>Nitrous oxide (N₂O) may elicit antidepressant effects after its elimination from the brain. We sought to investigate whether short-term administration of N₂O triggers power within the delta (0.5-4 Hz) and/or theta (4-7 Hz) frequency ranges in the electroencephalogram (EEG) after it's administration, as we have recently seen such rebound effects to N₂O in studies conducted on mice. Twenty healthy male participants were randomly allocated to receive 50% N₂O either continuously for 20 min (continuous group) or in two 10-min inhalations (repeated group) with 19-channel EEG. Median-averaged power spectral densities (PSDs) were calculated subject-, electrode-, and state-wise. Group-level data are topographically plotted and significant changes within specific frequency ranges for each condition are highlighted. The subjective effects in response to N₂O were studied with questionnaires. Fourteen participants completed the study (<i>n</i> = 7 participants/group). Spectrograms showed that the EEG transitions between N₂O and its withdrawal were extremely rapid in both groups and the effects remained stationary during specific states. Power in high-frequency bands (gamma) generally enhanced during N₂O administration along with power reductions in beta (and alpha) frequencies. Power in specific theta, but not delta, frequencies increase after the cessation of N₂O in several electrodes. However, direct comparison of the rebound EEG between the two treatment groups revealed negligible differences. Short-term administration of N₂O evokes increase of power in theta frequency, but not delta, band power upon gas withdrawal.<b>NEW & NOTEWORTHY</b> This study specifically addressed rebound EEG alterations within slow-wave frequency range upon withdrawal from N₂O in awake healthy participants. Short-term administration of N₂O increased power in theta, but not delta, frequency range upon gas withdrawal and this effect was readily reproduced with repeated dose.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":"133 5","pages":"1488-1496"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144030366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A coupled oscillator model predicts the effect of neuromodulation and a novel human tempo-matching bias.","authors":"Chloe Mondok, Martin Wiener","doi":"10.1152/jn.00348.2024","DOIUrl":"10.1152/jn.00348.2024","url":null,"abstract":"<p><p>Humans are known to exhibit endogenous neural oscillations in response to rhythmic stimuli that are phase-locked and frequency matched to those stimuli, a process known as entrainment. Yet, whether entrainment, as measured by electrophysiological recordings, reflects actual processing of rhythms or merely a reflection of the periodic nature of the stimulus is debated. Prior evidence for entrainment as a perceptual phenomenon comes from studies requiring subjects to listen to, compare sequentially, or detect features in rhythmic stimuli. However, one paradigm so far not used is one where subjects must listen to two simultaneous rhythms at different frequencies and adjust them to match. Here, human participants performed this task during EEG recordings (<i>experiment 1</i>), demonstrating spectral peaks at both tempo frequencies at frontocentral electrodes that shifted into alignment over the course of each trial. Behaviorally, participants tended to anchor the matched tempo to the starting comparison frequency, such that they underestimated the tempo for slower initial conditions and overestimated for faster initial conditions. A model of phase-coupled oscillators, in which both tempos were pulled toward one another, replicated both effects. This model further predicted that by enhancing the coupling strength of the constant tempo oscillator, both bias effects could be reduced. To test this, a second group of subjects performed the task while receiving 2 Hz transcranial alternating current stimulation (tACS) to the frontocentral region. Consistent with model predictions, tACS attenuated both behavioral effects, particularly for initially slower conditions. These results support entrainment as an endogenous process that mediates beat perception.<b>NEW & NOTEWORTHY</b> This work proposes how humans perceive the difference between two simultaneously presented tempos and bring them into perceived synchrony. EEG data provide evidence of entrainment to both tempos that move into alignment, and transcranial alternating current stimulation (tACS) data provide causal evidence that strengthening one tempo improves performance.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1607-1617"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143972237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Age and self-selected walking speed impact the generalization of locomotor memories across contexts.","authors":"Dulce M Mariscal, Carly J Sombric, Gelsy Torres-Oviedo","doi":"10.1152/jn.00432.2023","DOIUrl":"10.1152/jn.00432.2023","url":null,"abstract":"<p><p>Previous work has shown that compared with young adults, older adults generalize their walking patterns more across environments that impose different motor demands (i.e., split-belt treadmill vs. overground). However, in this previous study, all participants walked at a speed that was more comfortable for older adults than young participants, which leads to the question of whether young adults would generalize more their walking patterns than older adults when exposed to faster speeds that are more comfortable for them. To address this question, we examined the interaction between healthy aging and walking speed on the generalization of a pattern learned on a split-belt treadmill (i.e., legs moving at different speeds) to overground. We hypothesized that walking speed during split-belt walking regulates the generalization of walking patterns in an age-specific manner. To this end, groups of young (<30 yr old) and older (65+ yr old) adults adapted their gait on a split-belt treadmill at either slower or faster walking speeds. We assessed the generalization of movements between the groups by quantifying their aftereffects during overground walking, where larger overground aftereffects represent more generalization, and zero aftereffects represent no generalization. We found an interaction between age and walking speed in the generalization of walking patterns. More specifically, older adults generalized more when adapted at slower speeds, whereas younger adults did so when adapted at faster speeds. These results suggest that comfortable walking speeds lead to more generalization of newly acquired motor patterns beyond the training contexts.<b>NEW & NOTEWORTHY</b> The generalization of motor learning in humans depends on both internal factors, such as age, and external factors imposed by experimenters, like treadmill speeds. However, the interaction between these factors remains unclear. Our study revealed that older adults showed increased generalization when adapting to slower speeds, whereas younger adults exhibited this behavior at faster speeds. This implies that walking at unusual speeds acts as a contextual cue, restricting the generalization of motor patterns.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1410-1421"},"PeriodicalIF":2.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in gait asymmetry may be caused by adaptation of spinal reflexes.","authors":"Omar Refy, Owen Mo, Douglas J Weber, Hartmut Geyer","doi":"10.1152/jn.00206.2024","DOIUrl":"10.1152/jn.00206.2024","url":null,"abstract":"<p><p>In a recent human study, we found that adaptive changes in step length asymmetry (SLA) are correlated with similar changes in the H-reflex gains of the leg muscles during split-belt treadmill locomotion. Although this observation indicated a closer link between gait asymmetry and spinal reflex adaptation, it did not reveal their causal relationship. To better understand this relationship, here we use a neuromuscular model of human walking whose control relies primarily on spinal reflexes. Subjecting the model to split-belt treadmill locomotion with different combinations of belt speed and reflex gain patterns, we find that belt speed changes increase the variability in SLA but do not result in consistent SLA patterns as observed in human experiments, whereas reflex gain changes do. Furthermore, we find that the model produces SLA patterns similar to healthy adults when its reflex gains are adapted in a way similar to the H-reflex changes we observed in our previous study. The model also predicts SLA patterns similar to the ones observed for cerebellar degeneration patients when the reflexes do not adapt beyond a sudden dip at the time the ipsilateral belt speed is lowered. Our results suggest that SLA does not arise from imposing belt speed changes but requires the change of the reflex gains and that the dynamic adjustment of these gains may be an essential part of human gait control when encountering unexpected environmental changes such as uneven speed changes in split-belt treadmill locomotion.<b>NEW & NOTEWORTHY</b> This work uses computational modeling to investigate the role of spinal reflex tuning during locomotor adaptation. We show, in simulation, that tuning spinal reflex gains leads to gait asymmetry adaptation, not vice versa, and that patterns of gait adaptation on a split-belt treadmill are mostly driven by tuning of spinal reflexes, and not by biomechanical disturbances triggered by belt changes. The model further hints at the cerebellum as the source of spinal reflex modulation.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1208-1215"},"PeriodicalIF":2.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Torsional nystagmus and otolith dumping effects investigated by head circumduction.","authors":"Michele Corrado, Bianca Nicklen, Yuxiao Li, Toby Jack Ellmers, Adolfo Miguel Bronstein","doi":"10.1152/jn.00570.2024","DOIUrl":"10.1152/jn.00570.2024","url":null,"abstract":"<p><p>This study introduces a novel paradigm to induce the torsional vestibulo-ocular reflex (VOR) using head circumduction-a circular motion of the head combining extension, lateral rotation, and flexion of the neck. The aims were to <i>1</i>) evaluate the reliability of this maneuver in generating torsional nystagmus and <i>2</i>) explore the impact of postrotational head tilt on induced VOR responses. Fourteen healthy participants (age = 27.3 ± 5.3 yr) were tested using a three-dimensional (3-D) eye-tracker to record eye movements induced by head circumduction, performed at a frequency of 0.75 Hz. Participants were recorded on stopping in either a head-up or head-down condition. All participants showed robust postrotational torsional nystagmus. However, this was significantly shorter during head up (average duration = 10.7 ± 2.4 s, with a time constant of 4.1 ± 1.1 s) compared with head down (average duration = 15.7 ± 3.7 s, with a time constant of 7.2 ± 2.5 s; <i>P</i> = 0.0001). Vertical nystagmus was also observed in most participants, which was either disconjugate or overtly skewed. The shortening of torsional nystagmus duration and time constant in the head-up position supports <i>1</i>) a role for the velocity storage mechanism in the torsional VOR (which was previously disputed) and <i>2</i>) the existence of otolith dumping effects in the torsional VOR. In addition, the vertical ocular findings during the stopping response confirm that skewed eye movements can be generated by vertical semicircular canal activity. Our findings support the feasibility of head circumduction as a simple method for assessing semicircular and otolith effects on the torsional VOR.<b>NEW & NOTEWORTHY</b> Of all the triaxial vestibulo-ocular reflexes, torsional is the least studied for the need of heavy-duty rotational equipment. We introduce a simple self-paced paradigm to study the torsional vestibulo-ocular reflex-head circumduction, which produced in all participants stopping vestibular torsional nystagmus when circumduction was stopped. Forward head tilting significantly prolonged the postrotational torsional nystagmus duration-an \"otolith dumping effect\" that suggests, for the first time in humans, a role of the velocity storage mechanism in the torsional vestibulo-ocular reflex.</p>","PeriodicalId":16563,"journal":{"name":"Journal of neurophysiology","volume":" ","pages":"1295-1306"},"PeriodicalIF":2.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143730491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}