Perception Threshold Research Articles

Brain state and cortical layer-specific mechanisms underlying perception at threshold

Identical stimuli can be perceived or go unnoticed across successive presentations, producing divergent behavioral outcomes despite similarities in sensory input. We sought to understand how fluctuations in behavioral state and cortical layer and cell class-specific neural activity underlie this perceptual variability. We analyzed physiological measurements of state and laminar electrophysiological activity in visual area V4 while monkeys were rewarded for correctly reporting a stimulus change at perceptual threshold. Hit trials were characterized by a behavioral state with heightened arousal, greater eye position stability, and enhanced decoding performance of stimulus identity from neural activity. Target stimuli evoked stronger responses in V4 in hit trials, and excitatory neurons in the superficial layers, the primary feed-forward output of the cortical column, exhibited lower variability. Feed-forward interlaminar population correlations were stronger on hits. Hit trials were further characterized by greater synchrony between the output layers of the cortex during spontaneous activity, while the stimulus-evoked period showed elevated synchrony in the feed-forward pathway. Taken together, these results suggest that a state of elevated arousal and stable retinal images allow enhanced processing of sensory stimuli, which contributes to hits at perceptual threshold.

High Gradient Magnetic Fields Generated in Events on the 230 kV Electric Power Transmission Infrastructure: Human Exposure Analysis and Risk

This work presents a process for analyzing human exposure to high-gradient magnetic fields based on protection models for patients undergoing magnetic resonance examinations developed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). A series of events presented in the electrical energy transmission infrastructure is taken, with typical currents and front times, a case of extreme failure is added, and results are presented. Subsequently, with a classic lightning signal, compliance with the exposure to this type of field in the right-of-way strip of a transmission line is verified and validated in the event of a hypothetical atmospheric discharge impact event. Finally, a simulation is implemented with space discretization techniques, establishing the signal resulting from the magnetic field generated as a function of time. The exposure is evaluated using the presented model. Only in one of the analysis cases was it found that the perception threshold is exceeded at distances less than 0.6 cm, virtually a situation in which the worker has contact with the down conductor. With the results obtained and the cases analyzed, it is concluded that failures of this type do not generate significant exposure to high-gradient magnetic fields and do not exceed the determined perception thresholds.

The Problem of Perception in Sandor Márai’s Embers: An Advaitic Study

This article attempts to study the problem of perception in Sandor Márai’s celebrated novel Embers from the standpoint of the pramana (a method of knowledge) of Advaita Vedanta. An epistemic problem, the problem of perception, concerns the overwhelming questions of life, culminating in an enigmatic amalgamation of dilemmas and paradoxes. Genuine dilemmas and paradoxes problematize human relationships, which is evident in the complex narrative of Embers. Our contention in this article is to show how, even though enacted within the periphery of the purely fictional, Embers bears testimony to the complexities of life that are quickened by the limits of human perception, which keeps one from seeing how things really are by creating a shadow or reflected consciousness. Set against the backdrop of the Austro-Hungarian Empire, the novel opens up a dialogic space at the intersection of a triangular relationship enacted on the threshold of perception and its multidimensional problems.

Associations Between Vestibular Perception and Cognitive Performance in Healthy Adults.

A growing body of evidence has linked vestibular function to the higher-order cognitive ability in aging individuals. Past evidence has suggested unique links between vestibular function and cognition on the basis of end-organ involvement (i.e., otoliths versus canals). However, past studies have only assessed vestibular reflexes despite the diversity of vestibular pathways. Thus, this exploratory study aimed to assess associations between vestibular perception and cognition in aging adults to determine potential relationships. Fifty adults (21 to 84 years; mean = 52.9, SD = 19.8) were included in this cross-sectional study. All participants completed a vestibular perceptual threshold test battery designed to target perception predominantly mediated by each end-organ pair and intra-vestibular integration: 1 Hz y-translation (utricle), 1 Hz z-translation (saccule), 2 Hz yaw rotation (horizontal canals), 2 Hz right anterior, left posterior (RALP), and left anterior, right posterior (LARP) tilts (vertical canals), and 0.5 Hz roll tilt (canal-otolith integration). Participants also completed standard assessments of cognition and path integration: Digit Symbol Substitution Test (DSST), Trail Making Test (TMT), and the Gait Disorientation Test (GDT). Associations were assessed using Spearman rank correlation, and multivariable regression analyses. For correlation analyses, DSST correlated to RALP/LARP tilt, roll tilt, and z-translation. TMT-A only correlated to z-translation, and TMT-B correlated to roll tilt and z-translation after correcting for multiple comparisons. GDT correlated to RALP/LARP tilt and y-translation. In age-adjusted regression analyses, DSST and TMT-B were associated with z-translation thresholds and GDT was associated with y-translation thresholds. In this cross-sectional study, we identified associations between vestibular perceptual thresholds with otolith contributions and standard measures of cognition. These results are in line with past results suggesting unique associations between otolith function and cognitive performance.

Ankle torque variance is a better indicator of balance control performance than plantar perceptual sensitivity threshold.

We explored whether ankle torque variability or plantar perceptual threshold explains human balance control more effectively. We hypothesized that ankle torque variance is a better indicator of center of pressure (COP) velocity variance than plantar perceptual sensitivity. Two conditions were tested: loaded (23-kg vest added) and unloaded, as loading should diminish plantar sensitivity and increase COP velocity variability. We created a linear feedback model to assess the noise change in the sensorimotor loop induced by loading. Plantar sensitivity was quantified using a psychophysical approach while participants stood barefoot. A linear motor applied a force impulse on the participant's heel. A "yes-no" method of limits was selected to identify plantar sole sensory thresholds in both conditions. We observed reduced plantar sensitivity in loaded compared with unloaded conditions. In the loaded condition, participants exhibited greater COP velocity variance, with significant positive Pearson's correlations confirming a substantial association between ankle torque and COP velocity variances for both loaded [variance accounted for (VAF): r2 = 44.56%, P = 0.018] and unloaded conditions (VAF: r2 = 58.83%, P = 0.004). No significant correlation existed between COP velocity variance and plantar sensitivity threshold for both loaded (VAF: r2 = 0.002%, P = 0.99) and unloaded conditions (VAF: r2 = 21.81%, P = 0.35). The model confirmed an ∼88% rise in sensorimotor loop noise in the loaded condition. Ankle torque variance assesses the precision of nonperceptual and perceptual detection mechanisms in evaluating whole body motions and the accuracy in converting sensory cues into ankle torque.NEW & NOTEWORTHY Plantar cutaneous information contributes to balance control by modulating motor commands, but plantar perceptual sensitivity is a suboptimal indicator of balance performance. Multiple sensory cues encode whole body dynamics, guiding sensorimotor mechanisms to minimize body sway variability. Ankle torque variance is proposed as a superior measure for explaining balance control performance and evaluating the sensorimotor loop's functioning in balance control.

The Conflict between Top-down and Bottom-up Impairments in Consciousness Disorder in Schizophrenia

Introduction: Schizophrenia, a complex psychiatric disorder, is often associated with consciousness disorders, typically characterized by an elevated threshold of conscious perception. Over the years, a multitude of research has been dedicated to uncovering the primary cause of these disorders, leading to the development of several theories. Methods: In this article, two central answers to this problem have been reviewed. For this, the articles that were more related to the topic were selected. Based on the relevance to the subject of research, the main ideas of targeted articles are reordered to be comprehensible for the readers. Finally, the judgment and conclusion of the authors about the discussed problem are presented in this study. Discussion: The first theory, which we will explore in this article, suggests that the root cause of these disorders lies in defects within bottom-up processes. These processes, fundamental to our understanding of the world, involve the progression of sensory information from low-level perception to high-level awareness. In individuals with schizophrenia, these processes are believed to be compromised, leading to a distorted perception of reality. The second theory, in contrast, attributes the cause to impairments in top-down processes. These processes, which refer to the influence of high-level cognitive functions on lower-level sensory perception, are also considered dysfunctional in schizophrenic patients. This dysfunction is thought to disrupt the integration of sensory information, thereby affecting the individual's consciousness. However, a third perspective has emerged, suggesting the coexistence of impairments in both bottom- up and top-down processing. This perspective argues that to fully comprehend the nature of consciousness disorders in schizophrenia, it is crucial to determine the type and severity of both bottom-up and top-down impairments. Conclusion: In this review, we delve into these theories, examining the evidence supporting each and discussing their implications for our understanding of schizophrenia. Considering both bottom-up and top-down impairments, the third perspective offers a more holistic explanation for these disorders. We further argue that this perspective underscores the need for a more nuanced approach to studying schizophrenia. It suggests that future research should not only focus on these processes in isolation but also explore their interaction and the potential synergistic effects of their impairment. By doing so, we can hope to gain a more comprehensive understanding of consciousness disorders in schizophrenia, which could ultimately lead to more effective treatment strategies.

Optogenetic Manipulation of Covert Attention in the Nonhuman Primate.

Optogenetics affords new opportunities to interrogate neuronal circuits that control behavior. In primates, the usefulness of optogenetics in studying cognitive functions remains a challenge. The technique has been successfully wielded, but behavioral effects have been demonstrated primarily for sensorimotor processes. Here, we tested whether brief optogenetic suppression of primate superior colliculus can change performance in a covert attention task, in addition to previously reported optogenetic effects on saccadic eye movements. We used an attention task that required the monkey to detect and report a stimulus change at a cued location via joystick release, while ignoring changes at an uncued location. When the cued location was positioned in the response fields of transduced neurons in the superior colliculus, transient light delivery coincident with the stimulus change disrupted the monkey's detection performance, significantly lowering hit rates. When the cued location was elsewhere, hit rates were unaltered, indicating that the effect was spatially specific and not a motor deficit. Hit rates for trials with only one stimulus were also unaltered, indicating that the effect depended on selection among distractors rather than a low-level visual impairment. Psychophysical analysis revealed that optogenetic suppression increased perceptual threshold, but only for locations matching the transduced site. These data show that optogenetic manipulations can cause brief and spatially specific deficits in covert attention, independent of sensorimotor functions. This dissociation of effect, and the temporal precision provided by the technique, demonstrates the utility of optogenetics in interrogating neuronal circuits that mediate cognitive functions in the primate.

Effect of lubricated polishing and repolishing on gloss, roughness and material loss of nanoparticle resin composite

Aim: The study examined how different dry and lubricated polishing protocols impact the gloss, roughness, and material loss of nanoparticle resin composites, before and after simulated toothbrushing. Methods: One hundred cylindrical resin composite specimens were prepared and divided into an unpolished group and three test groups: Dimanto (DIM), Sof-Lex Pop-On (SOF), and Astrobrush (ASTRO). These groups underwent polishing dry, with water, or with or petroleum jelly. Surface parameters including gloss (Novo-Curve – Rhopoint TM, England), roughness, and material loss (MaxSurf XT 20, MahrGoettingen, Germany) were evaluated at four stages: baseline, polishing, simulated toothbrushing, and repolishing. Data were submitted to repeated measures ANOVA (P<0.05). Results: Lubrication did not affect the studied parameters after polishing with DIM. SOF showed improved performance without lubricants, whereas ASTRO achieved higher gloss and lower roughness when lubricated. In terms of surface material loss, DIM exhibited less material loss when used with petroleum jelly, SOF had reduced material loss when used with water, and ASTRO showed the most material loss when lubricated with petroleum jelly. Conclusion: The gloss, roughness, and surface material loss of the nanoparticle resin composite are influenced by the type of polisher used and the choice of lubricant. However, none of the differences observed surpassed the established thresholds for roughness or gloss perception, suggesting that these protocols are potentially viable for clinical application. Despite detectable differences among the polishing systems and lubricant combinations, all tested options are clinically acceptable. None of them exceeded the thresholds for biofilm accumulation or perceptible differences in surface gloss.

Postural control in episodic ataxia type 2: no evidence for increased vestibular excitability.

Patients with episodic ataxia type 2 (EA2) suffer from recurrent paroxysmal episodes of vertigo and oscillopsia. Pathophysiologically, altered neuronal excitability has been suspected. Vestibular excitability in 22 EA2 patients and 22 age-matched healthy participants was compared. Galvanic vestibular stimulation (GVS) was used to assess vestibular excitability by vestibular motion perception thresholds and mean postural sway velocity during various visual and proprioceptive conditions in the two groups. Control stimuli using sham and no GVS were established to identify the specificity of GVS-induced postural sway. In the baseline condition, EA2 patients showed larger postural instability. However, motion perception thresholds and the increase in mean postural sway velocity during vestibular stimulation (stimulation ratio) did not differ between groups. Postural sway during suprathreshold GVS increased with the vestibular motion perception threshold in EA2 patients, in contrast to healthy participants. The larger postural unsteadiness of EA2 patients probably reflects their progressive cerebellar degeneration. It is not related to abnormal visual (Romberg's ratio) or proprioceptive control of stance. Postural unsteadiness during vestibular stimulation does not indicate altered vestibular excitability in EA2 patients. However, vestibular stimulation increasingly destabilized postural control of EA2 patients with higher motion perception thresholds when proprioceptive information was diminished. This conclusion, however, is restricted to the postural control of EA2 patients in the interval between the vestibulo-cerebellar episodes.

Perceptual discrimination of action formidableness and friendliness and the impact of autistic traits

The ability to determine whether the actions of other individuals are friendly or formidable are key decisions we need to make to successfully navigate our complex social environment. In this study we measured perceptual performance when discriminating actions that vary in their friendliness or formidableness, and whether performance was related to the autistic traits of individuals. To do this, we developed an action morphing method to generate novel actions that lied along the action quality dimensions of formidableness and friendliness. In Experiment 1 we show that actions that vary along the formidableness or friendliness continua were rated as varying monotonically along the respective quality. In Experiment 2 we measured the ability of individuals with different levels of autistic traits to discriminate action formidableness and friendliness using adaptive 2-AFC procedures. We found considerable variation in perceptual thresholds when discriminating action formidableness (~ 540% interindividual variation) or friendliness (~ 1100% interindividual variation). Importantly, we found no evidence that autistic traits influenced perceptual discrimination of these action qualities. These results confirm that sensory enhancements with autistic traits are limited to lower level stimuli, and suggest that the perceptual processing of these complex social signals are not affected by autistic traits.

Color Ranges and Distribution of Human Teeth: A Prospective Clinical Study.

This study investigated the in vivo color range of human teeth using a research-grade noncontact spectroradiometer, analyzing the effects of gender, age, ethnicity, and lifestyle factors, including diet, smoking, and oral hygiene. A total of 1004 participants were recruited at two research sites and stratified by gender, age, and ethnicity, and data on their dietary and oral habits were collected. Noninvasive color measurements of an upper central incisor were performed using a spectroradiometer and a fiber-coupled Xe-Arc light source. Color differences were computed using the CIELAB and CIEDE2000 color difference formulas, statistically analyzed, and interpreted through comparisons with 50:50% perceptibility (PT) and acceptability (AT) thresholds for dentistry. CIELAB and CIEDE2000 color coordinate values varied significantly. Female teeth appeared lighter and less yellow than men's. Age correlated with darker, more chromatic teeth, stabilizing only after Age 46. Significant ethnic differences were observed, particularly between African-American and Asian participants. Coffee consumption impacted teeth yellowness and chromaticity, while tea had no significant effect. Frequent tooth brushing led to lighter teeth, and tooth whitening considerably influenced color, emphasizing the effect of cosmetic dental treatments. Smoking showed minimal impact, with slight discoloration noted among light smokers compared to nonsmokers. Color coordinate values by gender, age, and ethnicity exhibited statistically significant differences and, in most cases, noticeable color differences. With exceptions, the dietary/oral habits of the patient had a significant impact on the color of human teeth. The findings from this study provide detailed information and understanding of the color range and distribution of human teeth, which can help enhance the esthetic outcome of dental care and, consequently, the patient's satisfaction.

Dynamic Attending in percussionists and wind players

Percussionists have been shown to have superior temporal perception, but the underlying mechanisms for this advantage deserve further investigation. Dynamic Attending Theory, which posits the way attention aligns with rhythmic temporal structure, may explain why percussionists exhibit superior temporal perception. Percussionists may entrain more strongly to periodic stimuli than other musicians, and possibly at multiple hierarchical levels as opposed to only the tactus. To test these hypotheses, we asked a total of 41 musicians, 20 percussionists, and 21 wind players to complete a target detection task. Participants listened to periodic bursts of noise ( priming bursts) and tried to detect target bursts of noise at different temporal positions, some in phase and some out of phase with the initial noises. Target-burst amplitudes were calibrated to be at each participant’s perceptual threshold. We analyzed the hit rates at the different temporal positions, as well as the Fourier transform of those hit rate curves. No discernible difference between groups was found in the time domain, but in the frequency domain the percussionist group showed stronger fluctuation at a frequency that matched the priming bursts, but not at other hierarchical levels (specifically, double that frequency). Our findings help explain percussionists’ perceptual advantages, although questions about entrainment at different hierarchical levels deserve further consideration.

Impact of Speed Sintering on Translucency, Opalescence and Microstructure of Dental Zirconia with a Combination of 5 mol% and 3 mol% Yttria-Stabilized Zirconia.

Optical characteristics and microstructure of multilayered zirconia with different yttria contents in each layer can be influenced differently with a layer after speed sintering. The layer-wise translucency and opalescence of dental zirconia (E.max, E.max ZirCAD prime; Cercon, Cercon ht ML) after conventional (control) and speed sintering were analyzed using a spectrophotometer (n = 5). Specimens were subjected to microstructural analyses (n = 2) using field-emission scanning electron microscopy (FE-SEM) and phase analyses (n = 1) using high-resolution X-ray diffraction (HRXRD) and Rietveld refinement. The translucency parameter (TP) and opalescence parameter (OP) were analyzed using a 3-way ANOVA, followed by Scheffé's post hoc test (α = 0.05). The average grain size was analyzed using the Welch's t-test and Kruskal-Wallis test, followed by the Bonferroni-Dunn post hoc test (α = 0.05). Changes to the TP and OP after speed sintering were only observed in the dentin layers. Although the TP of E.max increased (p < 0.05), the difference was below the 50:50% perceptibility threshold (ΔE00 = 0.8). The OP of E.max decreased slightly, whereas that of Cercon increased slightly (p < 0.05). The microstructure and phase fraction of both zirconia barely changed. Therefore, speed sintering is considered to have a negligible clinical impact on the optical characteristics and microstructure.

Glucose-lowering medication associated with weight loss may limit the progression of diabetic neuropathy in type 2 diabetes.

Obesity is a major risk factor for diabetic peripheral neuropathy (DPN) in type 2 diabetes (T2D). This study investigated the effect of glucose lowering medication associated with weight change on DPN. Participants with T2D were grouped based on whether their glucose lowering medications were associated with weight gain (WG) or weight loss (WL). They underwent clinical, metabolic testing and assessment of neuropathic symptoms, vibration perception threshold (VPT), sudomotor function and corneal confocal microscopy (CCM) at baseline and follow-up between 4 and 7 years. Of 76 participants, 69.7% were on glucose lowering medication associated with WG, and 30.3% were on glucose lowering medication associated with WL. At baseline, participants in the WG group had a significantly longer duration of diabetes (p < .01), higher douleur neuropathique en 4 (DN4) score (p < .0001) and VPT (p = .01) compared with those in the WL group. Over a 56-month period, participants in the WG group showed no significant change in body weight (p = .11), HbA1c (p = .18), triglycerides (p = .42), DN4 (p = .11), VPT (p = .15) or Sudoscan (p = .43), but showed a decline in corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD) and corneal nerve fiber length (CNFL) (p < .0001). Participants in the WL group showed a reduction in weight (p = .01) and triglycerides (p < .05), no change in DN4 (p = .30), VPT (p = .31) or Sudoscan (p = .17) and a decline in the corneal nerve branch density (p < .01). Participants treated with glucose lowering medication associated with weight gain had worse neuropathy and greater loss of corneal nerves during follow-up, compared to patients treated with medication associated with weight loss.

Corneal nerve loss in adolescents with obesity and acanthosis nigricans.

Obesity and related metabolic abnormalities in adults are associated with peripheral neuropathy. Acanthosis nigricans (AN) is associated with insulin resistance, fatty liver, hyperlipidemia and glucose intolerance, all of which are risk factors for neuropathy. The aim of this study was to investigate if obese adolescents with AN have evidence of small nerve fiber damage. Adolescents with obesity with and without AN underwent body composition analysis, assessment of vibration perception threshold (VPT), monofilament sensitivity and corneal confocal microscopy (CCM) to quantify corneal nerve fiber density (CNFD), branch density (CNBD), length (CNFL) and inferior whorl length (IWL). Forty-six participants with obesity with (n = 31) and without (n = 15) AN aged 15(14-17) years were compared to 20 healthy controls aged 13(12-14) years. There was no difference in VPT, monofilament sensitivity and CCM measures between adolescents with obesity and controls. However, adolescents with AN had a significantly higher weight (P = 0.022), fat% (P = 0.029) and fat-muscle ratio (P = 0.012) with a lower CNFD (P = 0.045) compared to those with obesity without AN. Adolescents with obesity and acanthosis nigricans have a higher fat mass and small nerve fibre loss, indicative of a sub-clinical neuropathy.

Emerging Perspectives: The Interplay of Taste Perception and Oral Microbiota Composition in Dietary Preferences and Obesity.

Recent advancements in sensory research have brought to light the intricate relationship between taste perception and the oral microbiota, prompting investigations into their influence on human health, particularly in the context of dietary preferences and obesity. This review aims to update the current understanding of how oral microbiota influence taste perception and dietary choices, elucidating shared metabolic pathways between food processing and oral bacteria. Further, this review outlines the mechanisms underlying taste perception, emphasizing the role of taste receptors and taste buds in shaping sensory experiences influenced by genetic and environmental factors. Notably, we explore the bidirectional relationship between oral microbiota and taste sensitivity, highlighting the potential impact of microbial composition on taste perception thresholds and implications for dietary habits and health outcomes, such as obesity and dental caries. However, significant research gaps remain, particularly in the understanding of the molecular mechanisms linking oral microbiota with taste sensitivity, as well as the long-term effects of microbiota-targeted interventions. Future research should focus on longitudinal studies and experimental interventions to explore these connections more deeply, offering insights into potential strategies for promoting healthier dietary behaviors and managing diet-related non-communicable diseases.

Hand’s Vibration Perception Thresholds—A Systematic Review

The term vibration perception threshold (VPT) refers to the minimum amplitude required for a vibration to be consciously perceived. Knowledge of VPTs can be used to aid in the diagnosis of various pathologies, or to support design decisions during human-machine interface development. However, several factors affect VPT measurements (e.g., contactor size and pressure), thus, comparing VPT results from multiple studies should not be done without considering both the similarities and differences between said studies. This paper presents a systematic review on VPT results obtained across multiple studies, taking into consideration the different factors affecting the values reported in the literature. We intended to answer the following question: “What are the Vibration Perception Thresholds assessed on the glabrous skin of the hands and fingers of healthy humans?” To the best of our knowledge, this is the first attempt at conducting a systematic review focused specifically on numerical VPT results. Starting from 936 records, VPT results from 37 studies were organized according to various factors (gender, age, probe size, contact pressure, psychophysical method, room temperature, skin temperature, and hand location). This data was organized into a table, the Organization Table that is available for readers. This review can help future researchers and developers working on or working with the topic of human perception of vibrations by examining the factors that affect VPTs and discussing strategies to address them. We offer recommendations for future research and insights on how design engineers can utilize VPTs in the development of new haptic devices.

The Influence of Diffuse-Field Equalization on the Perception of Spatial Aliasing Introduced by Spherical Microphone Arrays

When a sound field is sampled by a finite number of microphones, the upper-frequency range of the recorded content is affected by spatial aliasing. The frequency beyond which aliasing-induced artifacts occur is related to the distance between a microphone and its nearest neighbors. In this study, ambisonics signals of order N = 7 were encoded from simulated recordings made by virtual spherical microphone arrays of varying characteristics (radius, sampling scheme, and sampling grid order). A diffuse-field equalization, the role of which is to lessen the aliasing-induced spectral coloration, was also considered in the tested conditions. These aliased stimuli were then compared with unaliased stimuli of order N = 7. Results showed that the diffuse-field equalization had a great impact on the perceived differences. A perceptual threshold was calculated in order to determine whether aliasing artifacts are likely to be audible based on the amount of aliasing-induced encoding error.

Visual pathways functioning in healthy pre-term adolescents: Sex but not gestational age effect.

Visuo-spatial and visuo-perceptual functioning is widely studied in preterm child and is strongly sex-specific. However, little to no data is available regarding male-female differences in preterm children and adolescents and about the interaction effect between sex and preterm birth. We studied 30 adolescents born preterm with normal cognitive and clinical neurological outcomes and 34 age-matched controls to investigate the interaction between levels of prematurity and sex in predicting the outcome of visual pathways functioning and to explore the relation between psychophysiological perceptive processing and neuropsychological performance. In the presence of prematurity, a greater female vulnerability in central visuo-cognitive processing (Form Coherence Task), but not in neuropsychological accuracy (Street Completion Test and Visual Object and Space Perception battery), seems to be more evident. Moreover, the psychophysical threshold is correlated to neuropsychological accuracy only in preterm females and not in males. These results support the idea that the male vulnerability in cognitive functioning described in prematurity-related developmental conditions is negligible during school age in children-adolescents with normal cognitive and clinical neurological outcomes. Visuo-perceptual functioning is widely studied in prematurity. However, few data are available about the interaction effect between sex and preterm birth in predicting visuo-perceptual functioning. We evidenced that in females born preterm with preserved cognitive abilities, the efficiency of the psychophysical visuo-perceptual threshold is reduced, but not related to the neuropsychological performance. Females may implement compensation strategies to achieve good performance regardless of the perceptual threshold. The present study addresses an important gap in literature, suggesting possible sex-specific outcomes in visuo-perceptual ability among preterm children and adolescents with normal intelligence and neurological outcomes.

Tinnitus Suppression with Electrical Stimulation at the Most Basal Contact of the Cochlear Implant Electrode as a Model for Round Window Stimulation.

The objective of this research was to test whether efficient tinnitus suppression could be achieved by electrical stimulation of the single most basal electrode contact of a cochlear implant. This approach simulates the effects of electrical stimulation using a round-window electrode. The study was performed in 10 adult cochlear implant patients showing complete or almost complete tinnitus suppression during electrical stimulation with their standard fitting-MAP. In all patients, tinnitus appeared again when the implant was switched off. Five Nucleus implant (1 CI532, 4 CI24RE CA) users and 5 Mi12xx series with FLEX28 electrodes with at least 6 months of CI experience were included. Two types of stimulation were presented at the most basal CI contact: a constant pulse train and a modulated pulse train. The variation in pulse rates was low rate (100-300 pps) and high (≥900 pps), and the current level ranged from the C-level to less than the T-level for both stimulation types. The effect of acute electrical stimulation at the most basal electrode contact was compared to the effect obtained with multichannel stimulation with the patient's current fitting MAP. Electrical stimulation was paused between tests with different stimulation types until tinnitus returned to baseline intensity. Patients reported Visual Analog Scale (VAS) scores for tinnitus loudness and intrusiveness during normal CI use and for each single contact stimulation type. Eight participants perceived complete suppression with one or more stimulation patterns. In 2 patients, suppression was less efficient than full-band CI stimulation. Louder stimuli are generally perceived as annoying and less effective in reducing tinnitus. In FLEX28 patients, it was also possible to obtain full tinnitus suppression with current amplitudes under the thresholds for auditory perception (this was not tested in patients with the Nucleus device). In 8 of the 10 included patients, we were able to obtain complete or almost complete tinnitus suppression with electrical stimulation at only 1 most basal electrode contact. Therefore, round-window stimulation with a single electrode may be a potential treatment for tinnitus in patients with significant residual hearing. The long-term effects of this therapy should be confirmed in future studies.