Unraveling the Keratin Expression in Oral Leukoplakia: A Scoping Review.

Intermediate filaments are one of three polymeric structures that form the cytoskeleton of epithelial cells. In the epithelium, these filaments are made up of a variety of keratin proteins. Intermediate filaments complete a wide range of functions in keratinocytes, including maintaining cell structure, cell growth, cell proliferation, cell migration, and more. Given that these functions are intimately associated with the carcinogenic process, and that hyperkeratinization is a quintessential feature of oral leukoplakias, the utility of keratins in oral leukoplakia is yet to be fully explored. This scoping review aims to outline the current knowledge founded on original studies on human tissues regarding the expression and utility of keratins as diagnostic, prognostic, and predictive biomarkers in oral leukoplakias. After using a search strategy developed for several scientific databases, namely, PubMed, Scopus, Web of Science, and OVID, 42 papers met the inclusion and exclusion criteria. One more article was added when it was identified through manually searching the list of references. The included papers were published between 1989 and 2024. Keratins 1-20 were investigated in the 43 included studies, and their expression was assessed in oral leukoplakia and dysplasia cases. Only five studies investigated the prognostic role of keratins in relation to malignant transformation. No studies evaluated keratins as a diagnostic adjunct or predictive tool. Evidence supports the idea that dysplasia disrupts the terminal differentiation pathway of primary keratins. Gain of keratin 17 expression and loss of keratin 13 were significantly observed in differentiated epithelial dysplasia. Also, the keratin 19 extension into suprabasal cells has been associated with the evolving features of dysplasia. The loss of keratin1/keratin 10 has been significantly associated with high-grade dysplasia. The prognostic value of cytokeratins has shown conflicting results, and further studies are required to ascertain their role in predicting the malignant transformation of oral leukoplakia.

Neurophysiological time course of timbre-induced music-like perception.

Traditionally, pitch variation in a sound stream has been integral to music identity. We attempt to expand music's definition, by demonstrating that the neural code for musicality is independent of pitch encoding. That is, pitchless sound streams can still induce music-like perception and a neurophysiological hierarchy similar to pitched melodies. Previous work reported that neural processing of sounds with no-pitch, fixed-pitch, and irregular-pitch (melodic) patterns, exhibits a right-lateralized hierarchical shift, with pitchless sounds favorably processed in Heschl's gyrus (HG), ascending laterally to nonprimary auditory areas for fixed-pitch and even more laterally for melodic patterns. The objective of this EEG study was to assess whether sound encoding maintains a similar hierarchical profile when musical perception is driven by timbre irregularities in the absence of pitch changes. Individuals listened to repetitions of three musical and three nonmusical sound-streams. The nonmusical streams were comprised of seven 200-ms segments of white, pink, or brown noise, separated by silent gaps. Musical streams were created similarly, but with all three noise types combined in a unique order within each stream to induce timbre variations and music-like perception. Subjects classified the sound streams as musical or nonmusical. Musical processing exhibited right dominant α power enhancement, followed by a lateralized increase in θ phase-locking and spectral power. The θ phase-locking was stronger in musicians than in nonmusicians. The lateralization of activity suggests higher-level auditory processing. Our findings validate the existence of a hierarchical shift, traditionally observed with pitched-melodic perception, underscoring that musicality can be achieved with timbre irregularities alone.NEW & NOTEWORTHY EEG induced by streams of pitchless noise segments varying in timbre were classified as music-like and exhibited a right-lateralized hierarchy in processing similar to pitched melodic processing. This study provides evidence that the neural-code of musicality is independent of pitch encoding. The results have implications for understanding music processing in individuals with degraded pitch perception, such as in cochlear-implant listeners, as well as the role of nonpitched sounds in the induction of music-like perceptual states.

The effect of elastic and viscous force fields on bimanual coordination.

Bimanual in-phase and anti-phase coordination modes represent two basic movement patterns with distinct characteristics-homologous muscle contraction and non-homologous muscle contraction, respectively. A method to understand the contribution of each limb to the overall coordination pattern involves detuning (Δω) the natural eigenfrequency of each limb. In the present experiment, we experimentally broke the symmetry between the two upper limbs by adding elastic and viscous force fields using a Kinarm robot exoskeleton. We measured the effect of this symmetry breaking on coordination stability as participants performed bimanual in-phase and anti-phase movements using their left and right hand in 1:1 frequency locking mode. Differences between uncoupled frequencies were manipulated via the application of viscous & elastic force fields and using fast and slow oscillation frequencies with a custom task developed using the Kinarm robotic exoskeleton. The effects of manipulating the asymmetry between the limbs were measured through the mean and variability of relative phase (ϕ) from the intended modes of 0 ° or 180 °. In general, participants deviated less from intended phase irrespective of coordination mode in all matched conditions, except for when elastic loads are applied to both arms in the anti-phase coordination. Second, we found that when force fields were mismatched participants exhibited a larger deviation from the intended phase. Overall, there was increased phase deviation during anti-phase coordination. Finally, participants exhibited higher variability in relative phase in mismatched force conditions compared to matched force conditions, with overall higher variability during anti-phase coordination mode. We extend previous research by demonstrating that symmetry breaking caused by force differences between the limbs disrupts stability in each coordination mode.

Auditory, tactile, and multimodal noise reduce balance variability.

Auditory and somatosensory white noise can stabilize standing balance. However, the differential effects of auditory and tactile noise stimulation on balance are unknown. Prior work on unimodal noise stimulation showed gains in balance with white noise through the auditory and tactile modalities separately. The current study aims to examine whether multimodal noise elicits similar responses to unimodal noise. We recorded the postural sway of healthy young adults who were presented with continuous white noise through the auditory or tactile modalities and through a combination of both (multimodal condition) using a wearable device. Our results replicate previous work that showed that auditory or tactile noise reduces sway variability with and without vision. Additionally, we show that multimodal noise also reduces the variability of sway. Analysis of different frequency bands of sway is typically used to separate open-loop exploratory (< 0.3 Hz) and feedback-driven (> 0.3 Hz) sway. We performed this analysis and showed that unimodal and multimodal white noise affected postural sway variability similarly in both timescales. These results support that the sensory noise effects on balance are robust across unimodal and multimodal conditions and can affect both mechanisms of sway represented in the frequency spectrum. In future work, the parameters of acoustic/tactile manipulation should be optimized for the most effective balance stabilization, and multimodal therapies should be explored for older adults with typical age-related balance instabilities.

Burning mouth disorder and Parkinson's disease: A scoping review of the literature.

BACKGROUND: Burning mouth disorder (BMD) is a complex medical condition characterized by a burning sensation in the mouth of fluctuating intensity. BMD is considered a diagnosis of exclusion, as oral burning can occur secondary to local or systemic conditions. Parkinson's disease (PD) is one such condition. OBJECTIVE: To provide a scoping review of the literature by assessing all articles written in English that investigated the relationship between BMD and PD. MATERIALS AND METHODS: Various databases (PubMed, Ovid, Web of Science, Science Direct and Scopus) and a search platform (EBSCOhost) were searched following similar investigative approaches. Duplicates were removed and reference lists of original studies were scrutinized for additional articles. Any decision about the inclusion/exclusion in the review was by consensus among the co-authors. RESULTS: Twenty-five original articles and one supplemental article were included in the final review, of which 13 met the inclusion criteria. These were further divided into five categories based on the study design/article, which included Prevalence studies (n = 6), Letter to the editor (n = 1), Incidence study (n = 1), Case reports (n = 2) and Experimental studies (n = 3). Strongest data was provided by epidemiological studies, which suggest BMD and PD are poorly associated. CONCLUSIONS: A scoping review of the existing literature does not suggest that PD patients are any more at risk of developing BMD compared to the general population. While there may be a link through the dopaminergic system as determined by imaging studies, it is unlikely that the pathogenesis of PD disease shares significant commonality with BMD.

Neural Encoding and Representation of Time for Sensorimotor Control and Learning.

The ability to perceive and produce movements in the real world with precise timing is critical for survival in animals, including humans. However, research on sensorimotor timing has rarely considered the tight interrelation between perception, action, and cognition. In this review, we present new evidence from behavioral, computational, and neural studies in humans and nonhuman primates, suggesting a pivotal link between sensorimotor control and temporal processing, as well as describing new theoretical frameworks regarding timing in perception and action. We first discuss the link between movement coordination and interval-based timing by addressing how motor training develops accurate spatiotemporal patterns in behavior and influences the perception of temporal intervals. We then discuss how motor expertise results from establishing task-relevant neural manifolds in sensorimotor cortical areas and how the geometry and dynamics of these manifolds help reduce timing variability. We also highlight how neural dynamics in sensorimotor areas are involved in beat-based timing. These lines of research aim to extend our understanding of how timing arises from and contributes to perceptual-motor behaviors in complex environments to seamlessly interact with other cognitive processes.

Differential motor system entrainment to auditory and visual rhythms.

Perception of, and synchronization to, auditory rhythms is known to be more accurate than with flashing visual rhythms. The motor system is known to play a role in the processing of timing information for auditory rhythm perception, but it is unclear if the motor system plays the same role for visual rhythm perception. One demonstrated component of auditory rhythm perception is neural entrainment at the frequency of the auditory rhythm. In this study, we use EEG to measure the entrainment of both auditory and visual rhythms from the motor cortex while subjects either tapped in synchrony with or passively attended to the presented rhythms. To isolate activity from motor cortex, we used independent component analysis to first separate out neural sources, then selected components using a combination of component topography, dipole location, mu activation, and beta modulation. This process took advantage of the fact that tapping activity results in reduced mu power, and characteristic beta modulation, which helped select motor components. Our findings suggest neural entrainment in motor components was stronger for visual rhythms than auditory rhythms and strongest during the tapping conditions for both modalities. We also find mu power increased in response to both auditory and visual rhythms. These findings indicate that the generally greater rhythm perception capabilities of the auditory system over the visual system may not depend entirely on neural entrainment in the motor system, but rather how the motor system is able to use the timing information made available to it. NEW & NOTEWORTHY We investigated neural entrainment in the motor system for both auditory and visual isochronous rhythms using electroencephalogram. Counter to expectations, our findings suggest stronger entrainment for visual rhythms than for auditory rhythms. Motor system activity was isolated with a novel procedure using independent component analysis as a means of blind source separation, along with known markers of mu activity from the motor system to identify motor components.

Cortical mu rhythms during action and passive music listening.

Brain systems supporting body movement are active during music listening in the absence of overt movement. This covert motor activity is not well understood, but some theories propose a role in auditory timing prediction facilitated by motor simulation. One question is how music-related covert motor activity relates to motor activity during overt movement. We address this question using scalp electroencephalogram by measuring mu rhythms-cortical field phenomena associated with the somatomotor system that appear over sensorimotor cortex. Lateralized mu enhancement over hand sensorimotor cortex during/just before foot movement in foot versus hand movement paradigms is thought to reflect hand movement inhibition during current/prospective movement of another effector. Behavior of mu during music listening with movement suppressed has yet to be determined. We recorded 32-channel EEG (n = 17) during silence without movement, overt movement (foot/hand), and music listening without movement. Using an independent component analysis-based source equivalent dipole clustering technique, we identified three mu-related clusters, localized to left primary motor and right and midline premotor cortices. Right foot tapping was accompanied by mu enhancement in the left lateral source cluster, replicating previous work. Music listening was accompanied by similar mu enhancement in the left, as well as midline, clusters. We are the first, to our knowledge, to report, and also to source-resolve, music-related mu modulation in the absence of overt movements. Covert music-related motor activity has been shown to play a role in beat perception (Ross JM, Iversen JR, Balasubramaniam R. Neurocase 22: 558-565, 2016). Our current results show enhancement in somatotopically organized mu, supporting overt motor inhibition during beat perception.NEW & NOTEWORTHY We are the first to report music-related mu enhancement in the absence of overt movements and the first to source-resolve mu activity during music listening. We suggest that music-related mu modulation reflects overt motor inhibition during passive music listening. This work is relevant for the development of theories relating to the involvement of covert motor system activity for predictive beat perception.

Modality-specific frequency band activity during neural entrainment to auditory and visual rhythms.

Rhythm perception depends on the ability to predict the onset of rhythmic events. Previous studies indicate beta band modulation is involved in predicting the onset of auditory rhythmic events (Fujioka et al., 2009, 2012; Snyder & Large, 2005). We sought to determine if similar processes are recruited for prediction of visual rhythms by investigating whether beta band activity plays a role in a modality-dependent manner for rhythm perception. We looked at electroencephalography time-frequency neural correlates of prediction using an omission paradigm with auditory and visual rhythms. By using omissions, we can separate out predictive timing activity from stimulus-driven activity. We hypothesized that there would be modality-independent markers of rhythm prediction in induced beta band oscillatory activity, and our results support this hypothesis. We find induced and evoked predictive timing in both auditory and visual modalities. Additionally, we performed an exploratory-independent components-based spatial clustering analysis, and describe all resulting clusters. This analysis reveals that there may be overlapping networks of predictive beta activity based on common activation in the parietal and right frontal regions, auditory-specific predictive beta in bilateral sensorimotor regions, and visually specific predictive beta in midline central, and bilateral temporal/parietal regions. This analysis also shows evoked predictive beta activity in the left sensorimotor region specific to auditory rhythms and implicates modality-dependent networks for auditory and visual rhythm perception.

Patterns of orofacial pain practice amongst oral medicine specialists in Australia.

BACKGROUND: This study aimed to evaluate and describe the current patterns of practice pertaining to orofacial pain amongst oral medicine specialists in Australia and provide insight into the access of care available to orofacial pain patients in Australia. METHODS: A survey involving questions relevant to orofacial pain, patient and practitioner demographics was designed and disseminated via an online polling platform to all Australian Health Practitioner Regulation Agency registered oral medicine specialists. Results were collated online, and simple descriptive statistics were utilised for data analysis. RESULTS: Twenty-six oral medicine specialists were included in this study, with a survey response rate of 81.2%. All specialists considered orofacial pain practice as part of the oral medicine specialty. 96.2% assessed and managed orofacial pain patients as part of their oral medicine practice. The greatest proportion (30.8%) of oral medicine specialists were practicing in Western Australia, a state which represents 10.3% of the Australian population. All respondents reportedly diagnose temporomandibular disorders, followed by orofacial neuropathy (96.2%) and headache or neurovascular disorders (80.8%). 92.3% of specialists managed orofacial neuropathy followed by temporomandibular disorders (84.6%) and headache or neurovascular disorders (50%). CONCLUSION: This is the first study to report on patterns of orofacial pain practice amongst oral medicine specialists in Australia. Findings demonstrate that oral medicine specialists in Australia are actively engaged in the assessment and management of the orofacial pain patient. There, however, appears to be disproportionate access to care by oral medicine specialists for patients with orofacial pain across Australia.

Is oral dysaesthesia a somatic symptom disorder?

Oral dysaesthesia is a condition characterised by persistent alteration to oral sensation, perceived by the patient to be abnormal and unpleasant, in the absence of mucosal pathology. Its aetiology remains uncertain. The condition was attributed as a psychosomatic disease for much of the 20th century, but with newer technologies, recent literature has mostly focused on a possible peripheral or central neuropathic aetiology to oral dysaesthesia. Despite this, psychotropic medications and psychological treatments remain forefront in the armamentarium for the management of oral dysaesthesia. This article aims to review the literature surrounding the pathogenesis of oral dysaesthesia and explore whether oral dysaesthesia is a somatic symptom disorder.

The effect of multisensory illusions on pain and perceived burning sensations in patients with Burning Mouth Syndrome: A proof-of-concept study.

BACKGROUND: Burning mouth syndrome (BMS) is a chronic pain disorder affecting the oral cavity. Previous work has shown promising analgesic results of bodily illusions in other chronic pain conditions. The aim of this proof-of-concept, pilot study was to investigate whether bodily illusions reduce pain in BMS patients. METHODS: Nine participants diagnosed with BMS underwent bodily illusions using a MIRAGE-mediated reality system. All participants completed four conditions and performed standardised movements of the tongue. First, a baseline condition was performed while the tongue was viewed at normal size and colour. Then, three conditions were performed in random order: resizing shrink, colour-based (blue tongue) and incongruent movement illusions. During each condition, participants rated overall pain intensity and the intensity of burning pain/sensation on the tongue. RESULTS: There was no difference in overall pain intensity ratings between conditions. However, a significant effect of condition was found for burning pain/sensation of the tongue. The colour illusion significantly reduced burning pain compared with baseline (MD = -12.8, 95% CI -20.7 to -4.8), corresponding to an average pain reduction of 32%. Exploratory analyses showed the colour illusion also significantly reduced pain compared with the shrink illusion (MD = -11.7, 95% CI -22.2 to -1.1). CONCLUSION: Using visual illusions to change tongue colour to blue resulted in significant reductions in burning pain/sensations in BMS patients for the duration of the illusion. This proof-of-concept study suggests that BMS patients may benefit from bodily illusions, and supports additional research using larger samples and more comprehensive control conditions.

The Role of Posterior Parietal Cortex in Beat-based Timing Perception: A Continuous Theta Burst Stimulation Study.

There is growing interest in how the brain's motor systems contribute to the perception of musical rhythms. The Action Simulation for Auditory Prediction hypothesis proposes that the dorsal auditory stream is involved in bidirectional interchange between auditory perception and beat-based prediction in motor planning structures via parietal cortex [Patel, A. D., & Iversen, J. R. The evolutionary neuroscience of musical beat perception: The Action Simulation for Auditory Prediction (ASAP) hypothesis. Frontiers in Systems Neuroscience, 8, 57, 2014]. We used a TMS protocol, continuous theta burst stimulation (cTBS), that is known to down-regulate cortical activity for up to 60 min following stimulation to test for causal contributions to beat-based timing perception. cTBS target areas included the left posterior parietal cortex (lPPC), which is part of the dorsal auditory stream, and the left SMA (lSMA). We hypothesized that down-regulating lPPC would interfere with accurate beat-based perception by disrupting the dorsal auditory stream. We hypothesized that we would induce no interference to absolute timing ability. We predicted that down-regulating lSMA, which is not part of the dorsal auditory stream but has been implicated in internally timed movements, would also interfere with accurate beat-based timing perception. We show ( n = 25) that cTBS down-regulation of lPPC does interfere with beat-based timing ability, but only the ability to detect shifts in beat phase, not changes in tempo. Down-regulation of lSMA, in contrast, did not interfere with beat-based timing. As expected, absolute interval timing ability was not impacted by the down-regulation of lPPC or lSMA. These results support that the dorsal auditory stream plays an essential role in accurate phase perception in beat-based timing. We find no evidence of an essential role of parietal cortex or SMA in interval timing.

Trajectory formation during sensorimotor synchronization and syncopation to auditory and visual metronomes.

Previous work on sensorimotor synchronization has investigated the dynamics of finger tapping and how individual movement trajectories contribute to timing accuracy via asymmetry in movement velocities. The present study investigated sensorimotor synchronization (in-phase) and syncopation (anti-phase) to both an auditory metronome and a visual flashing light at multiple frequencies to understand how individual movement phases contribute to the variability of timekeeping and error correction in different sensory modalities and with different task constraints. Results demonstrate that the proportional time spent in both the upward phase of movement and the holding phase of movement (time spent on the surface of the table) remain relatively invariant across both stimulus modalities and across tapping styles (syncopation and synchronization), but changes with interval duration, increasing as interval duration increases. The time spent in the downward phase of movement did significantly differ across stimulus modality and tapping style, increasing during both visuomotor timing and syncopation, accompanied by a significant decrease in flexion velocity during syncopation. Extension velocity and flexion time were found to be the main contributors to differences between visual and auditory timing, while flexion velocity and flexion time were found to be the main contributors to differences between synchronization and syncopation. No correlations were found between asynchrony and the upward, downward, or holding phases of movement, suggesting the existence of multiple error correction strategies.

Introduction and application of the multiscale coefficient of variation analysis.

Quantifying how patterns of behavior relate across multiple levels of measurement typically requires long time series for reliable parameter estimation. We describe a novel analysis that estimates patterns of variability across multiple scales of analysis suitable for time series of short duration. The multiscale coefficient of variation (MSCV) measures the distance between local coefficient of variation estimates within particular time windows and the overall coefficient of variation across all time samples. We first describe the MSCV analysis and provide an example analytical protocol with corresponding MATLAB implementation and code. Next, we present a simulation study testing the new analysis using time series generated by ARFIMA models that span white noise, short-term and long-term correlations. The MSCV analysis was observed to be sensitive to specific parameters of ARFIMA models varying in the type of temporal structure and time series length. We then apply the MSCV analysis to short time series of speech phrases and musical themes to show commonalities in multiscale structure. The simulation and application studies provide evidence that the MSCV analysis can discriminate between time series varying in multiscale structure and length.

Motor simulation theories of musical beat perception.

There is growing interest in whether the motor system plays an essential role in rhythm perception. The motor system is active during the perception of rhythms, but is such motor activity merely a sign of unexecuted motor planning, or does it play a causal role in shaping the perception of rhythm? We present evidence for a causal role of motor planning and simulation, and review theories of internal simulation for beat-based timing prediction. Brain stimulation studies have the potential to conclusively test if the motor system plays a causal role in beat perception and ground theories to their neural underpinnings.

Auditory white noise reduces postural fluctuations even in the absence of vision.

The contributions of somatosensory, vestibular, and visual feedback to balance control are well documented, but the influence of auditory information, especially acoustic noise, on balance is less clear. Because somatosensory noise has been shown to reduce postural sway, we hypothesized that noise from the auditory modality might have a similar effect. Given that the nervous system uses noise to optimize signal transfer, adding mechanical or auditory noise should lead to increased feedback about sensory frames of reference used in balance control. In the present experiment, postural sway was analyzed in healthy young adults where they were presented with continuous white noise, in the presence and absence of visual information. Our results show reduced postural sway variability (as indexed by the body's center of pressure) in the presence of auditory noise, even when visual information was not present. Nonlinear time series analysis revealed that auditory noise has an additive effect, independent of vision, on postural stability. Further analysis revealed that auditory noise reduced postural sway variability in both low- and high-frequency regimes (> or <0.3 Hz) of sway, suggesting that both spontaneous and feedback-driven aspects of postural fluctuations were influenced by acoustic noise. Our results support the idea that auditory white noise reduces postural sway, suggesting that auditory noise might be used for therapeutic and rehabilitation purposes in older individuals and those with balance disorders.

Effects of auditory noise intensity and color on the dynamics of upright stance.

Previous work assessing the effect of additive noise on the postural control system has found a positive effect of additive white noise on postural dynamics. This study covers two separate experiments that were run sequentially to better understand how the structure of the additive noise signal affects postural dynamics, while also furthering our knowledge of how the intensity of auditory stimulation of noise may elicit this phenomenon. Across the two experiments, we introduced three auditory noise stimulations of varying structure (white, pink, and brown noise). Experiment 1 presented the stimuli at 35 dB while Experiment 2 was presented at 75 dB. Our findings demonstrate a decrease in variability of the postural control system regardless of the structure of the noise signal presented, but only for high intensity auditory stimulation.

Adjunctive aids for the detection of oral squamous cell carcinoma and oral potentially malignant disorders: A systematic review of systematic reviews.

This study presents the results of systematic reviews on adjunctive tools in screening and diagnosis of oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD) and to determine if the current literature supports their use as either an adjunctive tool or replacement of gold standard techniques. Systemic reviews and meta-analysis that evaluated adjunctive tools including chemiluminescence, tissue autofluorescence, tissue fluorescence spectroscopy, vital staining and cytology techniques were systematically examined using AMSTAR II. Twenty-seven systematic reviews were included. Five studies had a low quality of evidence, and nine studies had a critically low quality of evidence. This review found limited evidence to recommend chemiluminescence, tissue autofluorescence tools and vital staining as diagnostic tools, but only serve as clinical adjuncts to conventional oral examination. Cytology techniques and narrow-band imaging may be utilised as a non-invasive diagnostic adjunctive tool for the detection of OSCC and the malignant transformation of OPMD. In conclusion, this paper provides evidence on several types of adjunctive tools and provides recommendations on their use in clinical practice. These tools are considered useful as clinical adjuncts but there is insufficient evidence for their use as a diagnostic tool to replace gold standard conventional oral examination and surgical biopsy.