Low-intensity Stimuli Research Articles

Neuropeptide S Encodes Stimulus Salience in the Paraventricular Thalamus

Evaluation of stimulus salience is critical for any higher organism, as it allows for prioritizing of vital information, preparation of responses, and formation of valuable memory. The paraventricular nucleus of the thalamus (PVT) has recently been identified as an integrator of stimulus salience but the neurochemical basis and afferent input regarding salience signaling have remained elusive. Here we report that neuropeptide S (NPS) signaling in the PVT is necessary for stimulus salience encoding, including aversive, neutral and reinforcing sensory input. Taking advantage of a striking deficit of both NPS receptor (NPSR1) and NPS precursor knockout mice in fear extinction or novel object memory formation, we demonstrate that intra-PVT injections of NPS can rescue the phenotype in NPS precursor knockout mice by increasing the salience of otherwise low-intensity stimuli, while intra-PVT injections of NPSR1 antagonist in wild type mice partially replicates the knockout phenotype. The PVT appears to provide stimulus salience encoding in a dose- and NPS-dependent manner. PVT NPSR1 neurons recruit the nucleus accumbens shell and structures in the prefrontal cortex and amygdala, which were previously linked to the brain salience network. Overall, these results demonstrate that stimulus salience encoding is critically associated with NPS activity in the PVT.

Gynephilic Men’s and Androphilic Women’s Visual Attention Patterns: The Effects of Gender and Sexual Activity Cues

ABSTRACT Men and women differ in the degree of specificity of sexual response and differences in attention to sexual cues may be a mechanism underlying these gendered patterns. The majority of previous research has examined attention using static images, which differ considerably from the dynamic videos used in studies of sexual response. To test attention as a potential mechanism involved in gendered sexual response, we used eye-tracking to examine visual attention patterns of 33 gynephilic men and 36 androphilic women to videos depicting preferred and nonpreferred gender targets engaging in varying sexual activities. Specificity of controlled attention was gendered, and this effect differed depending on the intensity of sexual activity cues depicted. Regardless of sexual activity cues, men’s controlled attention was gender-specific toward preferred targets. Sexual activity cues did, however, impact the degree to which women’s controlled attention was gender-specific. Specifically, women’s attention was gender-specific to low-intensity stimuli but nonspecific for masturbation and same-sex dyadic stimuli. Women’s attention was gender-specific for mixed-sex dyadic stimuli, but with greater attention directed toward nonpreferred gender targets. Overall, contextual cues impact women’s attention to a greater degree than men’s. Potential explanations for these findings and implications of stimulus selection for sexuality research are discussed.

Cybersickness and postural stability of first time VR users playing VR videogames

This study investigated symptoms of cybersickness and postural instability experienced by new users of head-mounted display virtual reality (HMD-VR), playing VR videogames over long and repeated sessions, and moderation of these symptoms by previous videogame experience and intensity of videogame stimulus.Cybersickness (SSQ) and postural stability (anterior-posterior path-velocity) of new users of VR (n = 80) was collected PRE-VR, POST-VR and 10 min after completing (POST-RECOVERY) a VR gaming experience. Users comprised of videogamers (n = 40) and non-videogamers (n = 40), who were randomly assigned to play either action (high-intensity stimuli) or adventure (low-intensity stimuli) games in VR for 30 min and repeated twice, one week apart.All participants, irrespective of gaming status and genre of game, experienced significant cybersickness after 30 min in VR using current-generation HMD-VR technology, and did not adapt (POST-VR) after two sessions. However videogamers were able to recover (POST-RECOVERY) from cybersickness induced in VR significantly better than non-videogamers.All participants experienced significantly better postural stability after 30 min in VR, irrespective of gaming experience or genre of game.Developers should create VR experiences that minimise negative symptoms of cybersickness and postural instability experience by new users of VR.

Effect of Biphasic kHz Field Stimulation on CA1 Pyramidal Neurons in Slices

Electrical stimulation in the kilohertz-frequency range has been successfully used for treatment of various neurological disorders. Nevertheless, the mechanisms underlying this stimulation are poorly understood. To study the effect of kilohertz-frequency electric fields on neuronal membrane biophysics we developed a reliable experimental method to measure responses of single neurons to kilohertz field stimulation in brain slice preparations. In the submerged brain slice pyramidal neurons of the CA1 subfield were recorded in the whole-cell configuration before, during and after stimulation with a biphasic charge balanced electric field at 2kHz, 5kHz or 10 kHz. The slice was placed in a 1 mm gap between two parallel 2 mm long platinum-iridium 0.1 mm diameter wire electrodes. Whole-cell recordings lasted for an hour or longer. Typically, a few 5-10 min long sessions of kHz-field stimulation (kHz-FS) with various frequency/amplitude combinations were applied to assess the type of neuronal response and possible changes of its membrane characteristics. It was found that kHz-field stimulation at all frequencies elicited reproducible excitatory neuronal responses lasting throughout stimulation period, but not after cessation of kHz-FS. During kHz-FS the rheobase usually decreased. In addition, spontaneous firing might be initiated in some silent neurons or became more intense in previously spontaneously active neurons. Response thresholds were in the range of 0.5-2 mA and were higher at higher frequencies. Blockade of glutamatergic synaptic transmission did not alter the magnitude of responses. Inhibitory synaptic input was not changed by kilohertz field stimulation. We conclude that kHz-frequency current applied in brain tissue has an excitatory effect on pyramidal neurons during stimulation. This effect is more prominent and occurs at a lower stimulus intensity at a frequency of 2kHz as compared to 5kHz and 10kHz.

How lesions at different locations along the visual pathway influence pupillary reactions to chromatic stimuli

PurposeTo examine systematically how prechiasmal, chiasmal, and postchiasmal lesions along the visual pathway affect the respective pupillary responses to specific local monochromatic stimuli.MethodsChromatic pupil campimetry (CPC) was performed in three patient groups (10 subjects with status after anterior ischemic optic neuropathy, 6 with chiasmal lesions, and 12 with optic tract or occipital lobe lesions (tumor, ischemia)) using red, low-intensity red, and blue local stimuli within the central 30° visual field. Affected areas - as determined by visual field defects revealed using conventional static perimetry - were compared with non-affected areas. Outcome parameters were the relative maximal constriction amplitude (relMCA) and the latency to constriction onset of the pupillary responses.ResultsA statistically significant relMCA reduction was observed in the affected areas of postchiasmal lesions with red (p = 0.004) and low-intensity red stimulation (p = 0.001). RelMCA reduction in the affected areas seemed more pronounced for low-intensity red stimulation (46.5% mean reduction compared to non-affected areas; 36% for red stimulation), however statistically not significant. In prechiasmal lesions, a statistically significant latency prolongation could be demonstrated in the affected areas with low-intensity red stimulation (p = 0.015).ConclusionOur results indicate that the choice of stimulus characteristics is relevant in detecting defects in the pupillary pathway of impairment along the visual pathway, favoring red stimuli of low intensity over blue stimuli. Such knowledge opens the door for further fundamental research in pupillary pathways and is important for future clinical application of pupillography in neuro-ophthalmologic patients.

P.022 The effect of vagus nerve stimulation on the quality of sleep in medically refractory epileptic patients

Background: The quality of sleep is frequently impacted in patients with epilepsy. Vagus Nerve Stimulation is a relatively common treatment used in patients with medically resistant epilepsy. Some studies show an improvement in quality of life, however, there is limited data on the impact on sleep quality. Methods: A database analysis was conducted on Medline, Embase, and Cochrane to find studies that examined the VNS’s effect on quality of sleep in medically resistant epilepsy. These studies included randomized clinical trails, case studies or reports, cohort studies, and systematic reviews. Results: 75 papers were reviewed and 16 studies from eight countries were included in the analysis. A total of 93 patients with ages ranged from 10 – 49 were included. Analyzing the change in the quality of sleep after VNS was evaluated using Multiple Sleep Latency Test. The literature showed that at low stimulus intensities, VNS treatment improves daytime sleepiness in patients. However, VNS setting titration has a dose-dependent effect on obstructive sleep apnea where higher VNS frequencies are related to higher apnea events. Conclusions: Limited data is available on the impact of VNS on the quality of sleep. Further studies are required to evaluate the improvement of sleep in patients with VNS.

Restoration of FMRP expression in adult V1 neurons rescues visual deficits in a mouse model of fragile X syndrome

Many people affected by fragile X syndrome (FXS) and autism spectrum disorders have sensory processing deficits, such as hypersensitivity to auditory, tactile, and visual stimuli. Like FXS in humans, loss of Fmr1 in rodents also cause sensory, behavioral, and cognitive deficits. However, the neural mechanisms underlying sensory impairment, especially vision impairment, remain unclear. It remains elusive whether the visual processing deficits originate from corrupted inputs, impaired perception in the primary sensory cortex, or altered integration in the higher cortex, and there is no effective treatment. In this study, we used a genetic knockout mouse model (Fmr1KO), in vivo imaging, and behavioral measurements to show that the loss of Fmr1 impaired signal processing in the primary visual cortex (V1). Specifically, Fmr1KO mice showed enhanced responses to low-intensity stimuli but normal responses to high-intensity stimuli. This abnormality was accompanied by enhancements in local network connectivity in V1 microcircuits and increased dendritic complexity of V1 neurons. These effects were ameliorated by the acute application of GABAA receptor activators, which enhanced the activity of inhibitory neurons, or by reintroducing Fmr1 gene expression in knockout V1 neurons in both juvenile and young-adult mice. Overall, V1 plays an important role in the visual abnormalities of Fmr1KO mice and it could be possible to rescue the sensory disturbances in developed FXS and autism patients.

IMAX: A new tool for assessment of motor axon excitability. A multicenter prospective study

ObjectiveThis study was undertaken to establish by a multicentric approach the reliability of a new technique evaluating motor axon excitability. MethodsThe minimal threshold, the lowest stimulus intensity allowing a maximal response by 1 mA increments (iUP) and then by 0.1 mA adjustments (iMAX) were prospectively derived from three nerves (median, ulnar, fibular) in four university centers (Liège, Marseille, Fraiture, Nice). iMAX procedure was applied in 28 healthy volunteers (twice) and 32 patients with Charcot-Marie-Tooth (CMT1a), chronic inflammatory demyelinating polyneuropathy (CIDP), Guillain-Barré syndrome (SGB) or axonal neuropathy. ResultsHealthy volunteers results were not significantly different between centers. Correlation coefficients between test and retest were moderate (> 0.5). Upper limits of normal were established using the 95th percentile. Comparison of volunteers and patient groups indicated significant increases in iMAX parameters especially for the CMT1a and CIDP groups. In CMT1a, iMAX abnormalities were homogeneous at the three stimulation sites, which was not the case for CIDP. ConclusionsThe iMAX procedure is reliable and allows the monitoring of motor axon excitability disorders. SignificanceThe iMAX technique should prove useful to monitor motor axonal excitability in routine clinical practice as it is a fast, non-invasive procedure, easily applicable without specific software or devices.

Reflection-Source Emissions Evoked with Clicks and Frequency Sweeps: Comparisons Across Levels.

According to coherent reflection theory, otoacoustic emissions (OAE) evoked with clicks (clicked-evoked, CE) or tones (stimulus frequency, SF) originate via the same mechanism. We test this hypothesis in gerbils by investigating the similarity of CE- and SFOAEs across a wide range of stimulus levels. The results show that OAE transfer functions measured in response to clicks and sweeps have nearly equivalent time-frequency characteristics, particularly at low stimulus levels. At high stimulus levels, the two OAE types are more dissimilar, reflecting the different dynamic properties of the evoking stimulus. At mid to high stimulus levels, time-frequency analysis reveals contributions from at least two OAE source components of varying latencies. Interference between these components explains the emergence of strong spectral microstructure. Time-frequency filtering based on mean basilar-membrane (BM) group delays (τBM) shows that late-latency OAE components (latency ~ 1.6τBM) dominate at low stimulus intensities and exhibit highly compressive growth with increasing stimulus intensity. In contrast, early-latency OAE components (~ 0.7τBM) are small at low stimulus levels but can come to dominate the overall response at higher intensities. Although the properties of long-latency OAEs are consistent with an origin via coherent reflection near the peak of the traveling wave, the generation place and/or mechanisms responsible for the early-latency OAE components warrant further investigation. Because their delay remains in constant proportion to τBM across sound intensity, long-latency OAEs, whether evoked with tones or clicks, can be used to predict characteristics of cochlear processing, such as the sharpness of frequency tuning, even at high stimulus levels.

5-day multi-session intermittent theta burst stimulation over bilateral posterior superior temporal sulci in adults with autism-a pilot study

BackgroundTheta burst stimulation (TBS), a patterned repetitive transcranial magnetic stimulation (rTMS) protocol with shorter simulation duration and lower stimulus intensity, could be a better protocol for individuals with autism spectrum disorder (ASD). Our study aimed to explore the impacts of intermittent TBS (iTBS) over the bilateral posterior superior temporal sulcus (pSTS) on intellectually able adults with ASD. MethodsIn this randomized, single-blinded, sham-controlled crossover trial, 13 adults with ASD completed iTBS for 5 consecutive days over the bilateral pSTS and inion (as a sham control) in a 16-weeks interval and in a randomly assigned order. The neuropsychological function was measured with the Wisconsin Card Sorting Test (WCST) for cognitive flexibility while the clinical outcomes were measured with both self-rate and parents-rate Autism Spectrum Quotient (AQ) before and after 5-day iTBS interventions. ResultsThe results revealed significantly immediate effects of multi-session iTBS over the bilateral pSTS on parent-rate autistic symptoms in adults with ASD. The post-hoc analysis revealed the impacts of multi-session iTBS on cognitive flexibility were affected by baseline social-communicative impairment and baseline cognitive performance. Besides, the impacts of multi-session iTBS on clinical symptoms was affected by the concurrent psychotropic medication use and baseline autistic symptoms. ConclusionsGiven the caveat of the small sample size and discrepancy of multiple informants, this pilot study suggests the therapeutic potential of 5-day multi-session iTBS over the pSTS in adults with ASD. Individual factors modulating the response to rTMS should be explicitly considered in the future trial.

Investigation of transient eye closure evoked with bright light in the patients with intermittent exotropia

BackgroundThis study aimed to present a simple method for evaluating transient eye closure (TEC) evoked by bright light and find the agreement between TEC and photosensitivity. We also assessed the associated factors with TEC in the patients with intermittent exotropia (IXT).MethodsIn this retrospective study, IXT patients were exposed to different brightness: darkness, low-intensity white light, and high-intensity white light using a near-infrared camera vision monitor system (Mon CV3, Metrovision, France). TEC was considered to be present if the subject closed his or her eyes immediately, and for more than half of the scotopic lid fissure distance in response to the high-intensity or low-intensity photopic stimulus of light, compared with lid fissure distance in the scotopic phase. We assessed the presence of photosensitivity using a questionnaire and evaluated the agreement between TEC and photosensitivity. We also investigated the sensory fusion, motor fusion, and pupil dynamic components for the existence of TEC in IXT patients.ResultsSixty-one patients with IXT were included. With the new method to evaluate TEC under different light intensities, 27 (44.3%) of the 61 IXT patients showed TEC, and 34 (55.7%) did not demonstrate TEC. TEC under high-intensity white light had a strong correlation with self-reporting photosensitivity (r = 0.77). The smaller angle of deviation at near was associated with the presence of TEC, with statistical significance (p = 0.04). Normal sensory status at a distance was significantly associated with TEC (p < 0.01). Multivariate analysis using multiple logistic regression analysis showed that normal sensory status was significantly associated with TEC (p = 0.02).ConclusionsThe test using a near-infrared camera vision monitor system was a simple and objective tool in identifying TEC evoked by bright light. The presence of TEC strongly correlated with self-reporting photosensitivity in patients with IXT. However, TEC may be an independent phenomenon with motor alignment, stereopsis, and pupil reflex pathway in patients with IXT.

On the variability of motor-evoked potentials: experimental results and mathematical model.

The purpose of this study was to determine the form of the relation between the mean amplitude and variance of motor-evoked potentials (MEP). To this end, single-pulse transcranial magnetic stimulation (TMS) was applied over the motor cortex of seventeen neurologically normal adult human subjects. The coil was positioned at a locus on the scalp that elicited an MEP in the first dorsal interosseous (FDI) at the lowest stimulus intensity. The subjects were instructed to maintain tonic activity in the FDI of 5 or 10% of the maximum voluntary contraction (MVC). The relation between MEP variance and amplitude was found to have an inverted parabolic shape, with maximal variance occurring near the half-maximal MEP amplitude. The coefficient of variation [Formula: see text] of MEPs decreased approximately as a rectangular hyperbolic function of MEP amplitude (i.e. ~ 1/MEP). A probabilistic model is proposed to explain the inverted parabolic relation between MEP variance and MEP amplitude, as well as the sigmoid shape of the MEP input-output relation (i.e. stimulus-response curve). The model is based on a description of α-motoneurons as binary threshold units, with unit thresholds distributed according to a positively skewed probability density function. The units are driven by noisy synaptic input currents having a Gaussian distribution. The model predicts an inverse parabolic relation between MEP variance and amplitude and a sigmoid input-output relation, as experimentally observed. Furthermore, increasing model motoneuron excitability by increasing the background synaptic drive increases MEP variability independently of MEP size, a surprising prediction. The model also explains the approximately rectangular hyperbolic relation between [Formula: see text] and MEP amplitude. The implications of these results for the interpretation of neurophysiological experiments and the statistical analysis of MEPs are discussed.

'External timing' of placebo analgesia in an experimental model of sustained pain.

Research on placebo analgesia commonly focuses on the impact of information about direction (i.e., increase or decrease of pain) and magnitude of the expected analgesic effect, whereas temporal aspects of expectations have received little attention so far. In a recent study, using short-lasting, low-intensity stimuli, we demonstrated that placebo analgesia onset is influenced by temporal information. Here, we investigate whether the same effect of temporal suggestions can be found in longer lasting, high-intensity pain in a Cold Pressor Test (CPT). Fifty-three healthy volunteers were allocated to one of three groups. Participants were informed that the application of an (inert-)cream would reduce pain after 5min (P5) or 30min (P30). The third group was informed that the cream only had hydrating properties (NE). All participants completed the CPT at baseline and 10 (Test 10) and 35min (Test 35) following cream application. Percentage change in exposure time (pain tolerance) from baseline to Test 10 (Δ10) and to Test 35 (Δ35) and changes in heart rate (HR) during CPT were compared between the three groups. Δ10 was greater in P5 than in NE and P30, indicating that analgesia was only present in the group that was expecting an early onset of analgesia. Δ35 was greater in P5 and P30 compared to NE, reflecting a delayed onset of analgesia in P30 and maintained analgesia in P5. HR differences between groups were not significant. Our data suggest that 'externally timing' of placebo analgesia may be possible for prolonged types of pain. Research on placebo effects mainly focuses on the influence of information about direction (i.e., increase or decrease of pain) and magnitude (i.e., strong or weak) of the expected effect but ignores temporal aspects of expectations. In our study in healthy volunteers, the reported onset of placebo analgesia followed the temporal information provided. Such 'external timing' effects could not only aid the clinical use of placebo treatment (e.g., in open-label placebos) but also support the efficacy of active drugs.

Acoustotactic response of mosquitoes in untethered flight to incidental sound

Mosquitoes are vectors for some of the most devastating diseases on the planet. Given the centrality of acoustic sensing in the precopulatory behavior of these vectors, the use of an exogenous acoustic stimulus offers the potential of interfering with the courtship behavior of these insects. Previous research on the acoustotactic response of mosquitoes has been conducted on tethered preparations using low-intensity sound stimuli. To quantify differences in acoustotactic responses between mosquitos of distinct sex and species, we examined the effects of incidental sound stimuli on the flight behavior of free-flying male vs. female Aedes aegypti and Anopheles gambiae mosquitoes. The key variables were sound frequency (100–1000 Hz) and intensity (67–103 dB, measured at 12.5 cm from the source), and the acoustotactic response was measured in terms of the relative increase in flight speed in response to the stimulus. The data show, for the first time, significant sex- and species-specific differences in acoustotactic responses. A. aegypti exhibited a greater response to sound stimulus compared to An. gambiae, and the response also extended over a larger range of frequencies. Furthermore, the males of both species displayed a greater acoustotactic response than females, with An. gambiae females exhibiting minimal response to sound.

Transcranial magnetic stimulation for tinnitus treatment

High prevalence of tinnitus, its negative influence on the quality of life and psychoemotional status of patients support need and extreme urgency of further research of various treatment methods. Rhythmic transcranial magnetic stimulation (rTMS) is an effective method of therapy in patients with chronic tinnitus. The optimal protocol for rhythmic stimulation is low-frequency (1 Hz) rTMS with low-intensity stimuli (below 110% of the motor threshold) with a limited number of stimuli per series. There is evidence that high-frequency rTMS in the area of relatively thin temporal bones can lead to excessive stimulation of the neural structures of the auditory cortex, which is undesirable considering the pathogenesis of this condition. The use of navigation technology in rTMS has no advantage in chronic tinnitus therapy, whereas the combined use of rTMS and transcranial electrical brain stimulation to increase the treatment efficacy is under active study. Considering the attributable favorable clinical safety profile of rTMS, as well as its known positive effects on anxiety and depression that are often seen in patients with tinnitus, we can recommend more widespread use of this method in real-world settings.

An automated homecage system for multiwhisker detection and discrimination learning in mice.

Automated, homecage behavioral training for rodents has many advantages: it is low stress, requires little interaction with the experimenter, and can be easily manipulated to adapt to different experimental conditions. We have developed an inexpensive, Arduino-based, homecage training apparatus for sensory association training in freely-moving mice using multiwhisker air current stimulation coupled to a water reward. Animals learn this task readily, within 1–2 days of training, and performance progressively improves with training. We examined the parameters that regulate task acquisition using different stimulus intensities, directions, and reward valence. Learning was assessed by comparing anticipatory licking for the stimulus compared to the no-stimulus (blank) trials. At high stimulus intensities (>9 psi), animals showed markedly less participation in the task. Conversely, very weak air current intensities (1–2 psi) were not sufficient to generate rapid learning behavior. At intermediate stimulus intensities (5–6 psi), a majority of mice learned that the multiwhisker stimulus predicted the water reward after 24–48 hrs of training. Both exposure to isoflurane and lack of whiskers decreased animals’ ability to learn the task. Following training at an intermediate stimulus intensity, mice were able to transfer learning behavior when exposed to a lower stimulus intensity, an indicator of perceptual learning. Mice learned to discriminate between two directions of stimulation rapidly and accurately, even when the angular distance between the stimuli was <15 degrees. Switching the reward to a more desirable reward, aspartame, had little effect on learning trajectory. Our results show that a tactile association task in an automated homecage environment can be monitored by anticipatory licking to reveal rapid and progressive behavioral change. These Arduino-based, automated mouse cages enable high-throughput training that facilitate analysis of large numbers of genetically modified mice with targeted manipulations of neural activity.

Effects of recording sequence on flicker electroretinographics recorded with natural pupils corrected for pupil area.

BackgroundA new handheld electroretinographic (ERG) recording system can record ERGs without mydriasis. However, this RETeval system cannot record ERGs from both eyes simultaneously. Thus, the purpose of this study was to determine whether the sequence of the ERG recordings will alter the results.MethodsWe studied 30 eyes of 30 healthy subjects. The flicker ERGs were recorded with the RETeval system without mydriasis and were elicited by 8, 16 and 32 photopic Td‐s. The flicker ERGs were recorded at two sessions. Session 1, the ERGs were recorded from the right eye and then the left eye, and Session 2, ERGs were recorded from the left eye then the right eye. We compared the implicit times, amplitudes and pupil diameters of the right eye between these two sessions.ResultsThe implicit time of the flicker ERGs was significantly shorter (p < 0.001), and the pupil diameters were significantly smaller (p = 0.013) at Session 2 than Session 1 but only for the lower stimulus intensity of eight Td‐s. There was a significant correlation of the differences in the implicit times and the differences in the pupil diameter between the two sessions (r = 0.406, p = 0.026).ConclusionsThe results indicate that the implicit times of the fundamental components of RETeval flicker ERGs can be affected by the sequence of recordings for lower stimulus intensities. This was most likely due to the differences of the pupil diameter during the recordings. We recommend that stronger stimuli be used to record the RETeval flicker ERGs to minimize the effects of the sequence of recordings.

Double neurophysiological certification of the filum terminale during sectioning surgery in pediatric population.

Background: Surgery of thickened-fibrolipoma filum terminale (FT) is performed routinely and without conflict but is not a risk-free surgical procedure. Intraoperative neurophysiological monitoring with mapping techniques can help to certify the FT before sectioning. However, a tailored surgical approach to cauda equina and a low threshold of surrounding nerve roots can confuse the final surgical decision. The aim is to demonstrate the usefulness of this double methodology for FT certification.Methods: A prospective study collected and reviewed retrospectively, from 2015 to 2018, 40 patients undergoing an FT surgery section were included in the study. After opening the dura mater and under the microscope, the cauda equina mapping is performed and the recording of muscles of the lower limbs and the external anal sphincter. In addition, a high-intensity stimulation of constant current of an isolated FT for a short period of time and in a dry surgical field, obtaining a bilateral-polyradicular-symmetrical response of cauda equina nerve roots.Results: Traditional motor mapping identified FT in 65% (26/40) of patients. Although, 35% (14/40) of the patients still have low-intensity stimuli response (<1 mA) of a muscle, especially anal sphincter. When this happens, the optimization of the dissection around FT is performed. After that, 25% (10/40) of the patients still having a muscle response in spite of seem isolated FT. Increasing the stimulation intensity up to 20 mA evoked a cauda equina response in all cases. No postoperative neurological impairment was observed in this series.Conclusion: This proposed methodology accurately confirms the FT so that it can be safely found and cut. The Double Neurophysiological Certification improves the gap of the traditional mapping techniques of cauda equina and can be used in a variety of more complex surgeries in this area.

Spatializing Emotions Besides Magnitudes: Is There a Left-to-Right Valence or Intensity Mapping?

The Spatial–Numerical Association of Response Codes (SNARC), namely the automatic association between smaller numbers and left space and between larger numbers and right space, is often attributed to a Mental Number Line (MNL), in which magnitudes would be placed left-to-right. Previous studies have suggested that the MNL could be extended to emotional processing. In this study, participants were asked to carry out a parity judgment task (categorizing one to five digits as even or odd) and an emotional judgment task, in which emotional smilies were presented with four emotional expressions (very sad, sad, happy, very happy). Half of the sample was asked to categorize the emotional valence (positive or negative valence), the other half was asked to categorize the emotional intensity (lower or higher intensity). The results of the parity judgment task confirmed the expected SNARC effect. In the emotional judgment task, the performance of both subgroups was better for happy than for sad expressions. Importantly, a better performance was found only in the valence task for lower intensity stimuli categorized with the left hand and for higher intensity stimuli categorized with the right hand, but only for happy smilies. The present results show that neither emotional valence nor emotional intensity alone are spatialized left-to-right, suggesting that magnitudes and emotions are processed independently from one another, and that the mental representation of emotions could be more complex than the bi-dimentional left-to-right spatialization found for numbers.

Neural correlates of conditioned pain responses in fibromyalgia subjects indicate preferential formation of new pain associations rather than extinction of irrelevant ones.

Behavioral studies have demonstrated aberrant safety processing in fibromyalgia subjects (FMSs) and suggested that patients accumulate new potential pain-related threats more effectively than extinguishing no longer relevant ones. The aim of the current study was to investigate the neural correlates of conditioned pain responses and their relationship with emotional distress in FMS (n = 67) and healthy controls (HCs, n = 34). Using functional magnetic resonance imaging, we traced conditioned pain responses to an identical moderately painful pressure (P30) depending on whether it was following a green (P30green) or a red (P30red) cue. The cues were previously associated with individually calibrated painful pressure stimuli of low and high intensity, corresponding to visual analogue scale 10 and 50 mm, respectively. Fibromyalgia subjects displayed increased P30green ratings over time, while P30red ratings remained elevated. Healthy controls adapted all pain ratings to resemble moderate pain. Fibromyalgia subjects exhibited increased activation for [P30green>P30red] in M1/anterior insula, whereas HC showed increased S2/mid-insula response to [P30red>P30green]. High pain catastrophizing scale (PCS) ratings in fibromyalgia (FM) covaried with heightened brain activation for [P30green] × PCS in left dorsolateral prefrontal cortex and medial prefrontal cortex/orbitofrontal cortex; and [P30green>P30red] × PCS in dorsal anterior cingulate cortex/mid-cingulate cortex; superior temporal pole, extending to anterior insula; bilateral thalamus; and posterior insula. Psychophysiological interaction analysis for FM [P30green>P30red] × PCS revealed a dissociation in functional connectivity between thalamus and bilateral inferior parietal lobe. In alignment with behavioral data, FMS displayed a cerebral response suggesting preferential formation of new pain-related associations while simultaneously maintaining no longer relevant ones. The opposite was observed in HC. Increased responses to pain-related threats in FM may contribute to dysfunctional pain-protective behaviors and disability.