Spatial Discrimination Research Articles

No Sex-Specific Effects of Artificial Selection for Relative Telencephalon Size during Detour Learning and Spatial Discrimination in Guppies (Poecilia reticulata)

Over recent decades, substantial research has focused on fish cognitive evolution to increase our understanding of the evolution of the enormous diversity of cognitive abilities that exists in fishes. One important but understudied aspect of cognitive evolution is sexual dimorphism in cognitive abilities. Sex-specific variation in brain region morphology has been proposed to be an important mechanism in this context. However, it is also common to find sex-specific variation in behavior and cognition without associated differences in brain morphology among the sexes. The telencephalon is the major cognitive center in the vertebrate brain and variation in telencephalon size has been associated with variation in cognition. Here, we utilize recently developed guppy artificial selection lines with ca. 10% differences in relative telencephalon size to investigate whether similar responses to selection of the size of this region may affect cognitive abilities differently in males and females. To that end, we compared two ecologically relevant aspects of cognition, detour learning and binary spatial discrimination. We tested the significance of the interaction between telencephalon size and sex, and we found no sex-specific effects of evolutionary increases in telencephalon size in the cognitive abilities tested. This study indicates that no clear cognitive sex-specific effects occur in response to rapid selection of telencephalon size. We suggest that future research on sexual dimorphism in cognitive abilities in fish could use various cognitive tests and examine telencephalic sub-regions to gain a more comprehensive understanding of their evolution.

Looking from shallow to deep: Hierarchical complementary networks for large scale pest identification

Pests are a major threat to the security of global agricultural production. Therefore, accurate identification of pests is vital for farmers to increase production and the associated income. In recent years, convolutional neural networks (CNNs) have become a mainstream method for pest identification. However, existing CNN-based approaches have a limitation due to the lack of key diverse feature representations, making it difficult to improve their recognition performance in large scale pest identification. To address the above limitation, we propose the hierarchical complementary network (HCNet) to capture pest feature representations and perform complementary fusion for obtaining hierarchical complementary information. Specifically, we first use a “ shallow to deep ” strategy to capture the hierarchical representations of the pest images. We then propose a spatial feature discrimination (SFD) module, which captures the key information in the hierarchical representations by boosting the spatial features of the current phase and suppressing the spatial features of the next phase. Finally, we design coordinate attention-guided feature complementary (CAFC) modules to fusion complementary information between features extracted from the SFD modules. Subsequently, we conduct experiments on the large scale pest dataset IP102. Without bells and whistles, the experimental results show that the proposed HCNet (ConvNext-B) achieves 75.36% accuracy on the test set, outperforming the existing state-of-the-art pest identification methods. Moreover, the proposed HCNet outperforms other state-of-the-art methods on different backbone networks. It will have a positive impact on the development of large scale pest identification methods.

Effects of skin moisturization on various aspects of touch showing differences with age and skin site

The human body is encompassed by a thin layer of tissue, the skin, which is heterogenous and highly specialized to protect the body and encode interactions with the external world. There is a fundamental scientific drive to understand its function, coupled with the need to preserve skin as we age, which impacts on our physiological and psychological well-being. In the present study, we aimed to define differences in touch perception between age groups and with skin cream application. We investigated touch on the finger, the forearm and cheek in younger (20–28 years, n = 22) and older (65–75 years, n = 22) females. We measured skin hydration, touch detection, finger spatial discrimination, forearm tactile pleasantness together with electrodermal activity, and perceptual ratings about cream use, skin dryness, and cosmetic habits. Glabrous finger skin became drier and touch performance was impaired with age, but these aspects were preserved in hairy skin. Skin moisturization immediately increased hydration levels, but did not significantly change touch perception. We also found that touch appreciation increased with age. We conclude that reduced finger capacity may impact self-evaluation of the skin and that long-term skin care strategies should focus on hydrating the hand to preserve touch capacities.

Scaling problem in Parkinson's disease patients with pain

IntroductionAlthough pain is common in Parkinson's disease (PD), the underlying mechanism remains unknown. Scaling function and dopaminergic hypofunction may contribute to pain development because increased pain sensitivity is observed in PD and is normalized after levodopa administration. We aimed to determine whether spatial discrimination (SD) and striatal dopaminergic activity (DA) differed between PD patients with and without pain. MethodsWe divided 90 patients with drug-naïve PD into two groups based on the presence or absence of pain and compared the SD threshold (SDT). We evaluated the correlation of the SDT with pain severity in PD with pain. We also compared the DA of 48 patients and analyzed the correlation with pain severity in PD patients with pain. ResultsThe SDTs did not differ between the two groups, but unmeasurable SDT was more frequent in PD with pain. There was a positive correlation of pain severity with the SDT of the more affected hand but no correlation with the SDT of the less affected hand. The DA did not differ between the groups. There was a negative trend of pain severity with the DA of the ventral striatum (VS) but no correlation with the other striatal subregions. ConclusionsPain in PD may be associated with scaling dysfunction in the sensory system. The abnormal scaling function would render the PD patient hypersensitive to even mild pain. The dopamine in the VS appears to be associated with pain severity; however, the relationship of striatal dopaminergic deficits with pain occurrence requires further investigation.

Interference of same/different learning by a spatial discrimination

Same/different learning by pigeons has long been of interest to experimental psychologists. In one of these procedures, matching-to-sample, responses to a sample stimulus result in the presentation of two comparison stimuli, one of which matches the sample, the other of which does not, and choice of the matching stimulus is reinforced. Evidence of a matching concept has been found when transfer has been found to new stimuli. Given the transfer results, it is surprising that acquisition of two matching tasks (or two mismatching tasks), has not been found to be any faster than one matching and one mismatching task (i.e., two compatible tasks do not appear to facilitate each other). In the present experiment, we asked if matching acquisition involving three colors would be retarded if the correct response to a fourth color was not matching but was spatial (e.g., if the sample is red choose the red comparison, if the sample is green choose the green comparison, if the sample is yellow choose the yellow comparison, but if the sample is blue choose the left comparison). We found that acquisition of this task was slower than acquisition of a four color matching task (i.e., when the sample was blue, the blue comparison was correct). The results suggest that there is an interaction among matching associations, such that common rules facilitate learning compared with having to learn an inconsistent (spatial) rule. This result provides further evidence of the development of a matching concept by pigeons.

Effects of vowel coloration on perceived directional offsets between single-syllable speech sounds

The ability of normal hearing listeners to spatially localize single-syllable speech sounds was examined via a two-interval, two alternative forced choice (2AFC) spatial offset discrimination task. To examine directional biases in horizontal sound localization, this task required listeners to observe the direction of an unseen second talker’s voice immediately after hearing a first talker’s voice in an alternative direction. Listeners reported only the relative frontward versus rearward spatial offset between the two voices heard during each trial. Headphone-based virtual acoustic simulation enabled blind listening tests that were completed without feedback to the listener, revealing the ease with which listeners judged the relative spatial offset of the second speech sound, although those judgments were strongly biased by differences in the source spectra. The single-syllable speech-sound stimuli were processed using individually measured head-related transfer functions (HRTFs) of 15 listeners for whom individually measured earphone transfer functions (ETFs) were also employed. While analysis of the 2AFC response data via receiver operating characteristic (ROC) curves showed a generally high level of directional sensitivity, systematic biases were observed that could be explained via the differences in vowel coloration between the first and second source presented during each trial.

Novel Electrode Designs for Electrotactile Stimulation of the Finger: A Comparative Assessment.

Electrotactile stimulation can be an attractive technology to restore tactile feedback in different application scenarios (e.g., virtual and augmented reality, tele-manipulation). This technology allows designing compact solutions with no mechanical elements that can integrate a high-density matrix of stimulation points. The present study introduced four novel multi-pad finger-electrode designs with different arrangements (two matrix and two circular) and shapes of active pads (producing sensation) and reference pads (ideally, no sensation produced below the pad). The electrodes were used to investigate the subjects' ability to spatially discriminate active pads within phalanges individually (6-9 pads) as well as across the full finger (18-19 pads). The tests were conducted in 12 subjects and the results showed that all designs led to high success rates when applied to the fingertip (70-81%). When tested on the full finger, the matrix and circular designs were characterized with similar performance (54-57%), and when the phalanges were analyzed individually, the spatial discrimination was best at the fingertip. Additionally, new approaches for faster amplitude calibration were proposed and tested, demonstrating that calibration duration can be reduced by approximately 40% compared to the standard approach of calibrating single pads individually. Finally, discrimination tests of dynamic tactile patterns were conducted using circular and matrix designs on the fingertip and full finger, respectively. The tests showed that the different patterns generated by the two arrangements could be clearly discriminated, especially in the case of full-finger matrix-style patterns. The present study, therefore, provides several important insights that are relevant when delivering tactile feedback to the finger using an electrotactile interface.

The impact of walking on the perception of multichannel electrotactile stimulation in individuals with lower-limb amputation and able-bodied participants

BackgroundOne of the drawbacks of lower-limb prostheses is that they do not provide explicit somatosensory feedback to their users. Electrotactile stimulation is an attractive technology to restore such feedback because it enables compact solutions with multiple stimulation points. This allows stimulating a larger skin area to provide more information concurrently and modulate parameters spatially as well as in amplitude. However, for effective use, electrotactile stimulation needs to be calibrated and it would be convenient to perform this procedure while the subject is seated. However, amplitude and spatial perception can be affected by motion and/or physical coupling between the residual limb and the socket. In the present study, we therefore evaluated and compared the psychometric properties of multichannel electrotactile stimulation applied to the thigh/residual limb during sitting versus walking.MethodsThe comprehensive assessment included the measurement of the sensation and discomfort thresholds (ST & DT), just noticeable difference (JND), number of distinct intervals (NDI), two-point discrimination threshold (2PD), and spatial discrimination performance (SD). The experiment involved 11 able-bodied participants (4 females and 7 males; 29.2 ± 3.8 years), 3 participants with transtibial amputation, and 3 participants with transfemoral amputation.ResultsIn able-bodied participants, the results were consistent for all the measured parameters, and they indicated that both amplitude and spatial perception became worse during walking. More specifically, ST and DT increased significantly during walking vs. sitting (2.90 ± 0.82 mA vs. 2.00 ± 0.52 mA; p < 0.001 for ST and 7.74 ± 0.84 mA vs. 7.21 ± 1.30 mA; p < 0.05 for DT) and likewise for the JND (22.47 ± 12.21% vs. 11.82 ± 5.07%; p < 0.01), while the NDI became lower (6.46 ± 3.47 vs. 11.27 ± 5.18 intervals; p < 0.01). Regarding spatial perception, 2PD was higher during walking (69.78 ± 17.66 mm vs. 57.85 ± 14.87 mm; p < 0.001), while the performance of SD was significantly lower (56.70 ± 10.02% vs. 64.55 ± 9.44%; p < 0.01). For participants with lower-limb amputation, the ST, DT, and performance in the SD assessment followed the trends observed in the able-bodied population. The results for 2PD and JND were however different and subject-specific.ConclusionThe conducted evaluation demonstrates that electrotactile feedback should be calibrated in the conditions in which it will be used (e.g., during walking). The calibration during sitting, while more convenient, might lead to an overly optimistic (or in some cases pessimistic) estimate of sensitivity. In addition, the results underline that calibration is particularly important in people affected by lower-limb loss to capture the substantial variability in the conditions of the residual limb and prosthesis setup. These insights are important for the implementation of artificial sensory feedback in lower-limb prosthetics applications.

Uncorrelated bilateral cortical input becomes timed across hippocampal subfields for long waves whereas gamma waves are largely ipsilateral.

The role of interhemispheric connections along successive segments of cortico-hippocampal circuits is poorly understood. We aimed to obtain a global picture of spontaneous transfer of activity during non-theta states across several nodes of the bilateral circuit in anesthetized rats. Spatial discrimination techniques applied to bilateral laminar field potentials (FP) across the CA1/Dentate Gyrus provided simultaneous left and right readouts in five FP generators that reflect activity in specific hippocampal afferents and associative pathways. We used a battery of correlation and coherence analyses to extract complementary aspects at different time scales and frequency bands. FP generators exhibited varying bilateral correlation that was high in CA1 and low in the Dentate Gyrus. The submillisecond delays indicate coordination but not support for synaptic dependence of one side on another. The time and frequency characteristics of bilateral coupling were specific to each generator. The Schaffer generator was strongly bilaterally coherent for both sharp waves and gamma waves, although the latter maintained poor amplitude co-variation. The lacunosum-moleculare generator was composed of up to three spatially overlapping activities, and globally maintained high bilateral coherence for long but not short (gamma) waves. These two CA1 generators showed no ipsilateral relationship in any frequency band. In the Dentate Gyrus, strong bilateral coherence was observed only for input from the medial entorhinal areas, while those from the lateral entorhinal areas were largely asymmetric, for both alpha and gamma waves. Granger causality testing showed strong bidirectional relationships between all homonymous bilateral generators except the lateral entorhinal input and a local generator in the Dentate Gyrus. It also revealed few significant relationships between ipsilateral generators, most notably the anticipation of lateral entorhinal cortex toward all others. Thus, with the notable exception of the lateral entorhinal areas, there is a marked interhemispheric coherence primarily for slow envelopes of activity, but not for pulse-like gamma waves, except in the Schafer segment. The results are consistent with essentially different streams of activity entering from and returning to the cortex on each side, with slow waves reflecting times of increased activity exchange between hemispheres and fast waves generally reflecting ipsilateral processing.

Exploring European Eel Anguilla anguilla (L.) Habitat Differences Using Otolith Analysis in Central-Western Mediterranean Rivers and Coastal Lagoons from Sardinia

An otolith shape and morphometric analysis was performed on European eel (Anguilla anguilla) subpopulations from five rivers and three coastal lagoons of Sardinia (central-western Mediterranean) to assess the role of different habitats on otolith development. Sagittal otolith shape was described by 11 harmonics from elliptic Fourier descriptors. Comparisons among the harmonics were run through canonical discriminant analyses (CDAs). The CDA reclassification rate (75.7%) demonstrated a spatial environmental discrimination among local eel subpopulations of Sardinia. The Euclidean distance values demonstrated a dissimilarity between the river and lagoon groups. The form factor and roundness shape indices were significantly higher in the river group than in the lagoon group. The distances of the first three rings to the otolith core revealed site-specific otolith development. Moreover, the annual otolith growth rate was faster in the lagoon group than in the river group. The differences among the studied sites in terms of sagittal otolith shape could relate to changes in different local stocks potentially related to environmental peculiarities. Establishing a direct correlation between otolith morphology and environmental factors is challenging, and further studies are needed to investigate the relationship between habitat type/environmental variation and growth/body characteristics of eels. Nevertheless, the achieved results suggest that this method can be considered to be a valuable tool for studying the ontogeny of the European eel.

The effects of transcranial electrical stimulation of the left dorsolateral prefrontal cortex on tactile spatial discrimination performance

The dorsolateral prefrontal cortex (DLPFC) plays a key role in tactile perceptual discrimination performance. Both transcranial random noise stimulation (tRNS) and anodal transcranial pulsed current stimulation (tPCS) have been shown to modulate neural activity in cortical regions. In this study, we aimed to determine whether tRNS and anodal tPCS over the left DLPFC would improve tactile perceptual discrimination performance of the right index finger in healthy neurological individuals. Subjects underwent a grating orientation task before, immediately after, and 30 min after applying tRNS in Experiment 1 or anodal tPCS in Experiment 2. tRNS application on the left DLPFC tended to enhance tactile perceptual discrimination performance. In contrast, the application of anodal tPCS over the left DLPFC did not affect tactile perceptual discrimination performance. These findings indicate that transcranial electrical stimulation to the left DLPFC may improve tactile perceptual discrimination performance, with effects that depend on stimulus modality.

Spatial price discrimination in a mixed duopoly input market

We uniquely examine an upstream mixed duopoly engaging in spatial price discrimination across a continuum of downstream markets. The monopoly firms in those markets face elastic final demand creating double marginalization. The upstream public firm faces a cost disadvantage relative to its private rival that declines as it is partially privatized. We show that the fully public firm improves social welfare relative to a private duopoly when it is not overly inefficient and when differentiation is sufficiently large. We also show that whenever this is the case, there exists an optimal degree of partial privatization that better aligns the trade-off between production costs and pricing distortions.

Applying cosmetic oil with added aromatic compounds improves tactile sensitivity and skin properties

Tactile sensitivity generally decreases with aging and is associated with impairments in skin properties. Products that hydrate the skin can combat touch deficits and aromatic compounds have been shown to improve skin mechanical properties. Thus, we tested a base cosmetic oil against a perfumed oil, applied to the skin of females aged 40–60 years, on tactile sensitivity and skin properties after repeated application. Tactile detection thresholds were assessed using calibrated monofilaments applied at the index finger, palm, forearm, and cheek. Spatial discrimination on the finger was assessed using pairs of plates with different inter-band spaces. These tests were performed before and after 1 month of base or perfumed oil use. We found that tactile detection thresholds and spatial discrimination improved only in perfumed oil group. A complementary immunohistological study using human skin was conducted to estimate the expression of olfactory receptor OR2A4 and elastic fiber length. Further, the expression of OR2A4 intensity and the length of elastic fibers increased significantly with oil application, where larger effects were seen with the perfumed oil. We conclude that the application of a perfumed oil may be of additional benefit and could repair, and even prevent, tactile decline with aging by ameliorating skin condition.

ESPRESSO: topological clustering of single-cell transcriptomics data to reveal informative genes for spatio–temporal architectures of cells

BackgroundBioinformatics capability to analyze spatio–temporal dynamics of gene expression is essential in understanding animal development. Animal cells are spatially organized as functional tissues where cellular gene expression data contain information that governs morphogenesis during the developmental process. Although several computational tissue reconstruction methods using transcriptomics data have been proposed, those methods have been ineffective in arranging cells in their correct positions in tissues or organs unless spatial information is explicitly provided.ResultsThis study demonstrates stochastic self-organizing map clustering with Markov chain Monte Carlo calculations for optimizing informative genes effectively reconstruct any spatio–temporal topology of cells from their transcriptome profiles with only a coarse topological guideline. The method, eSPRESSO (enhanced SPatial REconstruction by Stochastic Self-Organizing Map), provides a powerful in silico spatio–temporal tissue reconstruction capability, as confirmed by using human embryonic heart and mouse embryo, brain, embryonic heart, and liver lobule with generally high reproducibility (average max. accuracy = 92.0%), while revealing topologically informative genes, or spatial discriminator genes. Furthermore, eSPRESSO was used for temporal analysis of human pancreatic organoids to infer rational developmental trajectories with several candidate ‘temporal’ discriminator genes responsible for various cell type differentiations.ConclusionseSPRESSO provides a novel strategy for analyzing mechanisms underlying the spatio–temporal formation of cellular organizations.

Patterns matter: differential effects of stress‐inducing and novelty‐associated locus coeruleus firing on pretangle tau pathophysiology in a rat model

AbstractBackgroundThe brainstem locus coeruleus (LC), the main source of brain norepinephrine (NE), is critically involved in several functions including wakefulness, vigilance, attention, learning and memory. LC functioning is firing pattern‐dependent. Phasic pattern promotes novelty and learning, while high tonic activity associates with stress and anxiety. LC has been identified as a key structure in Alzheimer’s disease (AD) development. Braak and colleagues propose that soluble abnormally phosphorylated tau (pretangle tau) originates in the LC early in life. The spreading of pretangle tau to other neuromodulatory areas and transentorhinal cortex constitutes Braak’s pretangle AD stages. Pretangle stages appear to be universal in human, however, only a portion of us develop AD. The selective vulnerability of individuals for AD is not understood. We hypothesized that differential LC activity patterns, influence the pretangle tau pathophysiology and the development of AD.MethodIn this study, an AAV carrying pseudo‐phosphorylated human tau (AAV9‐DIO‐EGFP‐htauE14) was infused into the LC of 2‐3 month‐old TH‐CRE rats, mimicking the onset of tauopathy during puberty in humans. Another AAV containing ChR2 opsin (AAVdj‐DIO‐ChR2‐mCherry) was co‐infused with htauE14. Chronic light stimulation of the LC of either a 10 Hz phasic pattern or a 25 Hz tonic pattern was carried out for 6 weeks. The performance of ChR2 rats in a battery of behavioral assays was compared with control groups without ChR2 (AAVdj‐DIO‐mCherry), 10 months following the AAV infusion. This was followed by immunohistochemistry and Western blotting comparing different biomarkers.ResultPhasic LC activation improved spatial and olfactory discrimination of the htauE14 rats, while chronic tonic activation increased stress level of the rats and led to anhedonia. Phasic pattern rescued axonal degeneration observed in the control htauE14 rats, showing higher density of LC fibers in the piriform cortex and hippocampal dentate gyrus. Tonic LC activation did not rescue LC fiber degeneration, instead, worsened LC neuronal health indexed by elevated level of active caspase 3. The learning performance was positively correlated with the LC fiber density.ConclusionThese results argue that variations in environmental experiences associated with differing LC activity patterns may account for individual susceptibility to development of AD in humans.

Data mining to aquifer vulnerability assessment

The vulnerability map of aquifer pollution is a part of the early warning system to prevent the deterioration of groundwater quality. The weighted index overlay methods are commonly used to map aquifer vulnerability, but they have a series of drawbacks, indicating the need to apply alternative methods that introduce the least number of a priori considerations in the parameters processing and allow a more accurate interpretation of the final results. The purpose of this study is to use data mining techniques for cluster analysis to evaluate the vulnerability of groundwater pollution in the Almondarez Vento Karst Basin in Havana Province, Cuba, and compare the results with those obtained using the RISK method, which is a weighted index overlay method to study karstic aquifers. The variables selected to apply this unsupervised classification technique were: aquifer lithology, topographic slope of the terrain, soil attenuation index to pollutants, fault density per km2 and presence of direct infiltration zones. The cluster analysis achieved greater spatial discrimination and definition of areas with different degrees of vulnerability, demonstrating its high resolution power.

Following residential segregation by race spatiotemporally: A search for causality

AbstractObjectiveThe study tried to test three existing explanations on residential segregation through spatiotemporal modeling: (1) spatial assimilation, (2) racial prejudice and discrimination, and (3) residential preferences. Since residential segregation is fundamentally a spatial and longitudinal phenomenon, the analysis is expected to provide a fresh perspective on residential segregation.MethodThe study used a spatiotemporal modeling through integrated nested Laplace approximation, which is a Bayesian approach to very complex regression modeling, and the data came from the American Community Survey data from 2005 to 2019 at two different spatial levels—Public Use Microdata Area and census tracts.ResultsThe findings of this study showed that: (1) socioeconomic variables, including income, unemployment, and poverty, have meaningful impacts; (2) housing‐related variables do exert a significant impact on black household concentration; (3) the ratio of Asian and Hispanic populations turns out to be important predictors in a negative direction; and (4) even with the predictors, the non‐trivial temporal and spatiotemporal effects are discovered.ConclusionThe study reveals that a reductionist approach to residential segregation is unlikely to offer meaningful insights into the problem and that proper understanding is possible only when careful consideration of the spatiotemporal context is taken, including the spatial level.

A spatiotemporal graph generative adversarial networks for short-term passenger flow prediction in urban rail transit systems

ABSTRACT Most short-term passenger flow prediction methods only consider absolute errors as the optimization objective, which fails to account for spatial and temporal constraints on the predictions. To overcome these limitations, we propose a deep learning-based spatiotemporal graph generative adversarial network (STG-GAN) to accurately predict network-wide short-term passenger flows of the urban rail transit with higher efficiency and lower memory occupancy. Our model is optimized in an adversarial learning manner and includes (1) a generator network including gated temporal conventional networks (TCN) and weight sharing graph convolution networks (GCN) to capture structural spatiotemporal dependencies and generate predictions with a small computational burden; (2) a discriminator network including a spatial discriminator and a temporal discriminator to enhance spatial and temporal constraints of the predictions. The STG-GAN is evaluated on two datasets from Beijing Subway. Results illustrate its superiority and robustness.

Deformable channel non‐local network for crowd counting

AbstractBoth global dependency and local correlation are crucial for solving the scale variation of crowd. However, most of previous methods fail to take two factors into consideration simultaneously. Against the aforementioned issue, a deformable channel non‐local network, abbreviated as DCNLNet for crowd counting, which can simultaneously learn global context information and adaptive local receptive field is proposed. Specifically, the proposed DCNLNet consists of two well‐crafted designed modules: deformable channel non‐local block (DCNL) and spatial attention feature fusion block (SAFF). The DCNL encodes long‐range dependencies between pixels and the adaptive local correlation with channel non‐local and deformable convolution, respectively, benefiting for improving the spatial discrimination of features. While the SAFF aims to aggregate the cross‐level information, which interacts these features from different depths and learns specific weights for the feature maps with spatial attention. Extensive experiments are performed on three crowd counting benchmark datasets and experimental results indicate that the proposed DCNLNet achieves compelling performance compared to other representative counting models.

Hypnotic suggestions cognitively penetrate tactile perception through top-down modulation of semantic contents

Perception is subject to ongoing alterations by learning and top-down influences. Although abundant studies have shown modulation of perception by attention, motivation, content and context, there is an unresolved controversy whether these examples provide true evidence that perception is penetrable by cognition. Here we show that tactile perception assessed as spatial discrimination can be instantaneously and systematically altered merely by the semantic content during hypnotic suggestions. To study neurophysiological correlates, we recorded EEG and SEPs. We found that the suggestion “your index finger becomes bigger” led to improved tactile discrimination, while the suggestion “your index finger becomes smaller” led to impaired discrimination. A hypnosis without semantic suggestions had no effect but caused a reduction of phase-locking synchronization of the beta frequency band between medial frontal cortex and the finger representation in somatosensory cortex. Late SEP components (P80–N140 complex) implicated in attentional processes were altered by the semantic contents, but processing of afferent inputs in SI remained unaltered. These data provide evidence that the psychophysically observed modifiability of tactile perception by semantic contents is not simply due to altered perception-based judgments, but instead is a consequence of modified perceptual processes which change the perceptual experience.