Stimulus Modality Research Articles

Implicit perceptual learning of visual-auditory modality sequences

We examined perceptual modality sequence learning by presenting number words either visually (V) or auditorily (A). Manual responses were assigned to number identity, which was random, but the stimulus modalities followed a predictable 6-element sequence (e.g., VVAAVA). In two experiments, we assessed sequence-specific learning as the performance difference between the predictable sequence and a random transfer sequence. We expected learning benefits, but for visual trials we did not find any clear predictability benefits, and, surprisingly, for auditory trials we even found a general processing disadvantage (i.e., a predictability cost) for auditory trials (Experiment 1) or a cost-benefit pattern (Experiment 2, with equated shift rates in predictable and random sequences), with costs for auditory repetition trials and benefits for shifting to auditory processing. Hence, overall there was a general learning “cost” (Experiment 1) or a null net benefit of predictability for performance (Experiment 2). Together, the findings reveal a modality-specific sensitivity towards variations in shift frequency and modality predictability only for auditory trials, but there was no overall benefit of modality-specific sequence learning.

Periodic-Mechanical-Stimulus Enhanced Osteogenic Differentiation of Mesenchymal Stem Cells on Fe3O4/Mineralized Collagen Coatings.

Mechanical stimulus has been demonstrated to be critical to stem cell fate commitment and tissue repair. However, it still remains a challenge to remote control of the mechanical stimulus acting on cells. Here, we designed a magnetic Fe3O4/mineralized collagen coating on titanium substrate to regulate the osteogenic differentiation of mesenchymal stem cells (MSCs). The mode and intensity of the mechanical stimulus acting on cells could be controlled by adjusting the remote applied magnetic field. We demonstrated that the adhesion, proliferation, and differentiation of MSCs were strongly dependent on the mode and intensity of the mechanical stimuli. Strikingly, the periodic mechanical stimulus (12 h every other day, PMS) showed the significantly up-regulated expression of osteogenesis-related markers, ALP, compared to that of the static mechanical stimulus mode. The reason is proposed as (1) initially, PMS mode enables the coatings to have appropriate surface mechanical properties for promoting focal adhesion, integrin expression, and cytoskeleton development of MSCs, letting MSCs have good capability of accepting as well as transferring mechanical stimuli; (2) during MSCs growth, PMS mode may effectively manipulate MSCs cytoskeleton development and movement, and mechanotranduction mechanism could be well activated; thus, MSCs osteogenic differentiation is enhanced. This work therefore provides a novel strategy to engineer bioactive coatings with remote control over the intensity and mode of the mechanical stimulus acting on cells, and would have an impact on the design of smart biomaterial surfaces for orthopedic applications.

Intermittent Failure of Spike Propagation in Primary Afferent Neurons during Tactile Stimulation.

Primary afferent neurons convey somatosensory information to the CNS. Low-threshold mechanoreceptors are classified as slow-adapting (SA) or rapid-adapting (RA) based on whether or not they spike repetitively during sustained tactile stimulation; the former are subclassified as Type 1 or 2 based on the regularity of their spiking. Recording in vivo from DRGs of mice, we observed irregular- and regular-spiking units consistent with SA1 and SA2 low-threshold mechanoreceptors, but some units, which we labeled "semiregular," did not fit cleanly into the existing classification scheme. Analysis of their spiking revealed integer-multiple patterning in which spike trains comprised a fundamental interspike interval and multiples thereof. Integer-multiple-patterned spiking was reproduced by randomly removing spikes from an otherwise regular spike train, suggesting that semiregular units represent SA2 units in which some spikes are "missing." We hypothesized that missing spikes arose from intermittent failure of spikes to initiate or to propagate. Intermittent failure of spike initiation was ruled out by several observations: integer-multiple-patterned spiking was not induced by intradermal lidocaine, was independent of stimulus modality (mechanical vs optogenetic), and could not be reproduced in a conductance-based model neuron given constant input. On the other hand, integer-multiple-patterned spiking was induced by application of lidocaine to the DRG, thus pinpointing intermittent failure of spike propagation as the basis for integer-multiple-patterned spiking. Indeed, half of all SA2 units exhibited some missing spikes, mostly at low rate (<5%), which suggests that axons are efficient in using the lowest safety factor capable of producing near-perfect propagation reliability.SIGNIFICANCE STATEMENT The impedance mismatch at axon branch points can impede spike propagation. Reliability of spike propagation across branch points remains an open question and is especially important for primary afferents whose spikes must cross a T-junction to reach the CNS. Past research on propagation reliability has relied almost entirely on simulations and in vitro experiments. Here, recording in vivo, we linked a distinctive pattern of spiking to the intermittent failure of spike propagation at the T-junction. The rarity of failures argues that safety factor is high under physiological conditions, yet the occurrence of such failures argues that safety factor is just high enough to ensure near-perfect reliability, consistent with a good balance between propagation reliability and energy efficiency.

Common Neural System for Sentence and Picture Comprehension Across Languages: A Chinese-Japanese Bilingual Study.

While common semantic representations for individual words across languages have been identified, a common meaning system at sentence-level has not been determined. In this study, fMRI was used to investigate whether an across-language sentence comprehension system exists. Chinese–Japanese bilingual participants (n = 32) were asked to determine whether two consecutive stimuli were related (coherent) or not (incoherent) to the same event. Stimuli were displayed with three different modalities (Chinese written sentences, Japanese written sentences, and pictures). The behavioral results showed no significant difference in accuracy and response times among the three modalities. Multi-voxel pattern analysis (MVPA) of fMRI data was used to classify the semantic relationship (coherent or incoherent) across the stimulus modalities. The classifier was first trained to determine coherency within Chinese sentences and then tested with Japanese sentences, and vice versa. A whole-brain searchlight analysis revealed significant above-chance classification accuracy across Chinese and Japanese sentences in the supramarginal gyrus (BA 40), extending into the angular gyrus (BA 39) as well as the opercular (BA 44) and triangular (BA 45) parts of the inferior frontal gyrus in the left hemisphere (cluster-level FWE corrected p < 0.05). Significant above-chance classification accuracy was also found across Japanese sentences and pictures in the supramarginal (BA 40) and angular gyrus (BA 39). These results indicate that a common meaning system for sentence processing across languages and modalities exists, and it involves the left inferior parietal gyrus.

Assessing peripheral fibers, pain sensitivity, central sensitization, and descending inhibition in Native Americans: main findings from the Oklahoma Study of Native American Pain Risk.

Native Americans (NAs) have a higher prevalence of chronic pain than other U.S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Multiple pain stimulus modalities were used (eg, cold, heat, pressure, ischemic, and electric), and subjective (eg, pain ratings and pain tolerance) and physiological (eg, nociceptive flexion reflex) outcomes were measured. There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.

Hair Bundle Stimulation Mode Modifies Manifestations of Mechanotransduction Adaptation.

Sound detection in auditory sensory hair cells depends on the deflection of the stereocilia hair bundle which opens mechano-electric transduction (MET) channels. Adaptation is hypothesized to be a critical property of MET that contributes to the auditory system's wide dynamic range and sharp frequency selectivity. Our recent work using a stiff probe to displace hair bundles showed that the fastest adaptation mechanism (fast adaptation) does not require calcium entry. Using fluid-jet stimuli, others obtained data showing only a calcium-dependent fast adaptation response. Because cochlear stereocilia do not move coherently and the hair cell response depends critically on the magnitude and time course of the hair bundle deflection, we developed a high-speed imaging technique to quantify this deflection in rat cochlear hair cells. The fluid jet delivers a force stimulus, and force steps lead to a complex time course of hair bundle displacement (mechanical creep), which affects the hair cell's macroscopic MET current response by masking the time course of the fast adaptation response. Modifying the fluid-jet stimulus to generate a hair bundle displacement step produced rapidly adapting currents that did not depend on membrane potential, confirming that fast adaptation does not depend on calcium entry. MET current responses differ with stimulus modality and will shape receptor potentials of different hair cell types based on their in vivo stimulus mode. These transformations will directly affect how stimuli are encoded.SIGNIFICANCE STATEMENT Mechanotransduction by sensory hair cells represents a key first step for the sound sensing ability in vertebrates. The sharp frequency tuning and wide dynamic range of sound sensation are hypothesized to require a mechanotransduction adaptation mechanism. Recent work indicated that the apparent calcium dependence of the fastest adaptation differs with the method of cochlear hair cell stimulation. Here, we reconcile existing data and show that calcium entry does not drive the fastest adaptation process, independent of the stimulation method. With force stimulation of the hair bundle, adaptation manifests differently than with displacement stimulation, indicating that the stimulation mode of the hair bundle will affect the hair cell receptor current and stimulus coding.

A meta-analysis of the emotional victim effect for female adult rape complainants: Does complainant distress influence credibility?

Rape cases have a disproportionately high attrition rate and low conviction rate compared with other criminal offenses. Evaluations of a rape complainant's credibility often determine whether a case progresses through the criminal justice system. Even though emotional demeanor is not related to witness honesty or accuracy, distressed rape complainants are perceived to be more credible than complainants who present with controlled affect. To understand the extent and robustness of the influence of emotional demeanor on credibility judgments of female adult rape complainants, we conducted a systematic review, meta-analysis, and p-curve analysis of the experimental simulated decision-making literature on the influence of complainant emotional demeanor on complainant credibility. The meta-analysis included 20 studies with participants who were criminal justice professionals (e.g., police officers and judges), community members, and mock jurors (N = 3128). Results suggest that distressed demeanor significantly increased perceptions of complainant credibility, with a small to moderate effect size estimate. Importantly, the results of p-curve analysis suggest that reporting bias is not a likely explanation for the effect of emotional demeanor on rape complainant credibility. Sample type (whether perceivers were criminal justice professionals or prospective jurors) and stimulus modality (whether perceivers read about or watched the complainant recount the alleged rape) were not found to moderate the effect size estimate. These results suggest that effective methods of reducing reliance on emotional demeanor to make credibility judgments about rape complainants should be investigated to make credibility assessments fairer and more accurate. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Motor sources of dual-task interference: Evidence for effector-based prioritization in dual-task control.

Dual tasking is known to yield performance costs. Corresponding research has often focused on early or central task processing stages, that is, on features related to stimulus processing or response selection. Here, we demonstrate the important role of the final (late) stage of task processing by studying effects of effector system combinations. We used pairwise combinations of tasks requiring oculomotor, manual, vocal, and pedal responses, triggered by visual/auditory stimuli. Across task combinations, we compared dual-task costs among effector systems (e.g., oculomotor, vocal, and pedal) under controlled conditions, that is, when combined with the same "context effector" (e.g., manual) in the other task. The dual-task cost pattern was strongly determined by the particular combination of effector systems in line with the assumption of an ordinal effector-based prioritization pattern (oculomotor > pedal > vocal > manual), and could not be explained by classic "first-come, first-served" accounts of central processing. Stimulus modality and its mapping to effector systems affected reaction times (RTs), but the impact on the general prioritization scheme was negligible, suggesting a more substantial influence of output (compared with input) system characteristics on dual-task capacity scheduling. The results call for a distinct effector system weighting mechanism in models of dual-task control. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Bimodal modulation of background activity in an identified descending interneuron.

In the absence of any obvious input, sensory neurons and interneurons can display resting or spontaneous activity. This is often regarded as noise and removed through trial averaging, although it may reflect history-dependent modulation of tuning or fidelity and, thus, be of functional relevance to downstream interneurons. We investigated the history dependence of spontaneous activity in a pair of identified, bimodal descending interneurons of the stick insect, called contralateral ON-type velocity-sensitive interneurons (cONv). The bilateral pair of cONv conveys antennal mechanosensory information to the thoracic ganglia, where it arborizes in regions containing locomotor networks. Each cONv encodes the movement velocity of the contralateral antenna, but also substrate vibration as induced by discrete tapping events. Moreover, cONv display highly fluctuating spontaneous activity that can reach rates similar to those during antennal movement at moderate velocities. Hence, cONv offer a unique opportunity to study history-dependent effects on spontaneous activity and, thus, encoding fidelity in two modalities. In this work, we studied unimodal and cross-modal effects as well as unilateral and bilateral effects, using bilateral recordings of both cONv neurons, while moving one antenna and/or delivering taps to induce substrate vibration. Tapping could reduce spontaneous activity of both neurons, whereas antennal movement reduced spontaneous activity of the contralateral cONv neuron only. Combination of both modalities showed a cooperative effect for some parameter constellations, suggesting bimodal enhancement. Since both stimulus modalities could cause a reduction of spontaneous activity at stimulus intensities occurring during natural locomotion, we conclude that this should enhance neuronal response fidelity during locomotion.NEW & NOTEWORTHY The spontaneous activity in a pair of identified, descending insect interneurons is reduced depending on stimulus history. At rest, spontaneous activity levels are correlated in both interneurons, indicating a common drive from background activity. Whereas taps on the substrate affect both interneurons, antennal movement affects the contralateral interneuron only. Cross-modal interaction occurs, too. Since spontaneous activity is reduced at stimulus intensities encountered during natural locomotion, the mechanism could enhance neuronal response fidelity during locomotion.

Chronic Pain Patients' Gaze Patterns toward Pain-Related Information: Comparison between Pictorial and Linguistic Stimuli.

Background and Objectives: The attentional bias and information processing model explained that individuals who interpret pain stimuli as threatening may increase their attention toward pain-related information. Previous eye tracking studies found pain attentional bias among individuals with chronic pain; however, those studies investigated this phenomenon by using only one stimulus modality. Therefore, the present study investigated attentional engagement to pain-related information and the role of pain catastrophizing on pain attentional engagement to pain-related stimuli among chronic pain patients by utilizing both linguistic and visual stimulus. Materials and Methods: Forty chronic pain patients were recruited from the rehabilitation center, the back pain clinic, and the rheumatology department of Chung-Ang University Hospital in Seoul, Korea. Patients observed pictures of faces and words displaying pain, presented simultaneously with neutral expressions, while their eye movements were measured using the eye tracking system. A t-test and ANOVA were conducted to compare stimulus pairs for the total gaze duration. Results: Results revealed that chronic pain patients demonstrated attentional preference toward pain words but not for pain faces. An ANOVA with bias scores was conducted to investigate the role of pain catastrophizing on attentional patterns. Results indicated that chronic pain patients with high pain catastrophizing scores gazed significantly longer at pain- and anger-related words than neutral words compared to those with low pain catastrophizing scores. The same patterns were not observed for the facial expression stimulus pairs. Conclusions: The results of the present study revealed attentional preference toward pain-related words and the significant role of pain catastrophizing on pain attentional engagement to pain-related words. However, different patterns were observed between linguistic and visual stimuli. Clinical implications related to use in pain treatment and future research suggestions are discussed.

Comparison of transcranial electrical stimulation regimens for effects on inhibitory circuit activity in primary somatosensory cortex and tactile spatial discrimination performance

Transcranial electrical stimulation (tES) can be used to modulate inhibitory circuits in primary somatosensory cortex, resulting in improved somatosensory function. However, efficacy may depend on the specific stimulus modality and patterns. For instance, transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), and transcranial pulsed current stimulation (tPCS) were found to stably and effectively modulate neuronal excitability, while anodal transcranial direct current stimulation (tDCS) appeared less effective overall but with substantial response heterogeneity among subjects. Therefore, we compared the effects of tES applied to primary somatosensory cortex on somatosensory evoked potential paired-pulse depression (SEP-PPD) and tactile discrimination performance in 17 neurologically healthy subjects. In Experiment 1, somatosensory evoked potential N20/P25_SEP-PPD, N20_SEP-PPD, and P25_SEP-PPD responses were assessed before and immediately after anodal tDCS, tACS (stimulation frequency, 140 Hz), tRNS (stimulation frequency, 0.1–640 Hz), anodal tPCS (pulse width, 50 ms; inter-pulse interval, 5 ms), and sham stimulation applied to primary somatosensory cortex. In Experiment 2, a grating orientation task (GOT) was performed before and immediately after the same anodal tDCS, tRNS, anodal tPCS, and sham stimulation regimens. Anodal tDCS and anodal tPCS decreased N20_SEP-PPD, and tRNS increased the first N20 SEP amplitude. Furthermore, tRNS and anodal tPCS decreased GOT discrimination threshold (improved performance). These results suggest that tRNS and anodal tPCS can improve sensory perception by modulating neuronal activity in primary somatosensory cortex.

The Representation of Semantic Information Across Human Cerebral Cortex During Listening Versus Reading Is Invariant to Stimulus Modality.

An integral part of human language is the capacity to extract meaning from spoken and written words, but the precise relationship between brain representations of information perceived by listening versus reading is unclear. Prior neuroimaging studies have shown that semantic information in spoken language is represented in multiple regions in the human cerebral cortex, while amodal semantic information appears to be represented in a few broad brain regions. However, previous studies were too insensitive to determine whether semantic representations were shared at a fine level of detail rather than merely at a coarse scale. We used fMRI to record brain activity in two separate experiments while participants listened to or read several hours of the same narrative stories, and then created voxelwise encoding models to characterize semantic selectivity in each voxel and in each individual participant. We find that semantic tuning during listening and reading are highly correlated in most semantically selective regions of cortex, and models estimated using one modality accurately predict voxel responses in the other modality. These results suggest that the representation of language semantics is independent of the sensory modality through which the semantic information is received.SIGNIFICANCE STATEMENT Humans can comprehend the meaning of words from both spoken and written language. It is therefore important to understand the relationship between the brain representations of spoken or written text. Here, we show that although the representation of semantic information in the human brain is quite complex, the semantic representations evoked by listening versus reading are almost identical. These results suggest that the representation of language semantics is independent of the sensory modality through which the semantic information is received.

Transcriptional Bursting and Co-bursting Regulation by Steroid Hormone Release Pattern and Transcription Factor Mobility.

Genes are transcribed in a discontinuous pattern referred to as RNA bursting, but the mechanisms regulating this process are unclear. Although many physiological signals, including glucocorticoid hormones, are pulsatile, the effects of transient stimulation on bursting are unknown. Here we characterize RNA synthesis from single-copy glucocorticoid receptor (GR)-regulated transcription sites (TSs) under pulsed (ultradian) and constant hormone stimulation. In contrast to constant stimulation, pulsed stimulation induces restricted bursting centered around the hormonal pulse. Moreover, we demonstrate that transcription factor (TF) nuclear mobility determines burst duration, whereas its bound fraction determines burst frequency. Using 3D tracking of TSs, we directly correlate TF binding and RNA synthesis at a specific promoter. Finally, we uncover a striking co-bursting pattern between TSs located at proximal and distal positions in the nucleus. Together, our data reveal a dynamic interplay between TF mobility and RNA bursting that is responsive to stimuli strength, type, modality, and duration.

The parietal operculum preferentially encodes heat pain and not salience.

Substantial controversy exists as to which part of brain activity is genuinely attributable to pain-related percepts and which activity is due to general aspects of sensory stimulation, such as its salience, or the accompanying arousal. The challenge posed by this question rests largely in the fact that pain per se exhibits highly intense but unspecific characteristics. These therefore should be matched by potential control conditions. Here, we used a unique combination of functional magnetic resonance imaging (fMRI) and behavioral and autonomic measures to address this longstanding debate in pain research. Subjects rated perceived intensity in a sequence alternating between heat and sound stimuli. Neuronal activity was monitored using fMRI. Either modality was presented in 6 different intensities, 3 of which lay above the pain threshold (for heat) or the unpleasantness threshold (for sound). We performed our analysis on 26 volunteers in which psychophysiological responses (as per skin conductance responses [SCRs]) did not differ between the 2 stimulus modalities. Having thus ascertained a comparable amount of stimulation-related but unspecific activation, we analyzed stimulus-response functions (SRFs) after painful stimulation and contrasted them with those of the matched acoustic control condition. Furthermore, analysis of fMRI data was performed on the brain surface to circumvent blurring issues stemming from the close proximity of several regions of interest located in heavily folded cortical areas. We focused our analyses on insular and peri-insular regions that are strongly involved in processing of painful stimuli. We employed an axiomatic approach to determine areas showing higher activation in painful compared to nonpainful heat and, at the same time, showing a steeper SRF for painful heat compared to unpleasant sound. Intriguingly, an area in the posterior parietal operculum emerged, whose response showed a pain preference after satisfying all axiomatic constraints. This result has important implications for the interpretation of functional imaging findings in pain research, because it clearly demonstrates that there are areas where activity following painful stimulation is not due to general attributes or results of sensory stimulation, such as salience or arousal. Conversely, several areas did not conform to the formulated axioms to rule out general factors as explanations.

Event related message processing: perceiving and remembering changes in films with and without soundtrack

ABSTRACT Hollywood movies provide continuous audiovisual information. Yet, information conveyed by movies address different sensory systems. For a broad variety of media applications (such as multimedia learning environments) it is important to understand the underlying cognitive principles. This project addresses the interplay of auditory and visual information during movie perception. Because auditory information is known to change basic visual processes, it is possible that movie perception and comprehension depends on stimulus modality. In this project, we report three experiments that studied how humans perceive and remember changes in visual and audiovisual movie clips. We observed basic processes of event perception (event segmentation, change detection, and memory) to be independent of stimulus modality. We thus conclude that event boundary perception is a general perceptual-cognitive mechanism and discuss these findings with respect to current cognitive psychological and media psychological theories.

Conjunctival Redness Response to Corneal Stimulation.

The conjunctiva is an integral component of the ocular surface, and its vasculature forms a terminal vascular bed of the human internal carotid artery. No research on the response of conjunctival vasculature to ocular surface stimulation exists; however, it is essential to understand the local physiological and pathological responses to such a stimulus. The purpose of this study was to characterize the ocular redness levels in healthy participants after the application of noxious corneal stimulation. A computerized Belmonte pneumatic esthesiometer was used to determine detection thresholds (using ascending method of limits) and to randomly deliver mechanical and chemical stimuli from levels of detection threshold to twice the threshold in 50% steps to the central cornea of 15 healthy subjects. For each suprathreshold stimulus, a spectrophotometer was used to measure ipsilateral and contralateral conjunctival redness before and after delivery of the corneal stimulus. Redness between the stimulated and unstimulated eyes was analyzed using dependent t tests. The effects of stimulus intensity and modality on conjunctival redness were analyzed using repeated-measures analysis of variance (ANOVA). Tukey honestly significant difference tests were used for all post hoc analyses. P ≤ .05 was considered statistically significant. In mechanical and chemical stimulation experiments, the stimulated eye became redder than the unstimulated eye (all t tests, P > .05). On average, redness increased from baseline as the corneal stimulus intensity increased with corneal stimulation (ANOVA, P < .05). Chemical stimulation produced greater conjunctival redness than did mechanical stimulation at all stimulation levels (ANOVA, P < .05; all Tukey honestly significant difference tests, P < .05). Stimulation of the central cornea by noxious mechanical and chemical stimuli evokes a dose-dependent autonomic conjunctival redness response. Chemical stimulation of the cornea seems to evoke a greater response compared with mechanical stimulation. This study serves as a basis for the characterization of the local stimulus-response neural circuitry relating nociceptive ocular surface stimuli to autonomic responses.

Cross-modal representations in early visual and auditory cortices revealed by multi-voxel pattern analysis.

Primary sensory cortices can respond not only to their defined sensory modality but also to cross-modal information. In addition to the observed cross-modal phenomenon, it is valuable to research further whether cross-modal information can be valuable for categorizing stimuli and what effect other factors, such as experience and imagination, may have on cross-modal processing. In this study, we researched cross-modal information processing in the early visual cortex (EVC, including the visual area 1, 2, and 3 (V1, V2, and V3)) and auditory cortex (primary (A1) and secondary (A2) auditory cortex). Images and sound clips were presented to participants separately in two experiments in which participants' imagination and expectations were restricted by an orthogonal fixation task and the data were collected by functional magnetic resonance imaging (fMRI). We successfully decoded categories of the cross-modal stimuli in the ROIs except for V1 by multi-voxel pattern analysis (MVPA). It was further shown that familiar sounds had the advantage of classification accuracies in V2 and V3 when compared with unfamiliar sounds. The results of the cross-classification analysis showed that there was no significant similarity between the activity patterns induced by different stimulus modalities. Even though the cross-modal representation is robust when considering the restriction of top-down expectations and mental imagery in our experiments, the sound experience showed effects on cross-modal representation in V2 and V3. In addition, primary sensory cortices may receive information from different modalities in different ways, so the activity patterns between two modalities were not similar enough to complete the cross-classification successfully.

Simultaneously applying cathodal tDCS with low frequency rTMS at the motor cortex boosts inhibitory aftereffects

BackgroundTranscranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) can modulate cortical excitability. However, the combining effect of tDCS and rTMS at the same motor cortex is unknown. New methodsWe have recently developed a new stimulation protocol that simultaneously combines two well-documented methods. Eleven right-handed healthy subjects undertook four sessions at the left cortical representation area of right first dorsal interosseous muscle in randomized order, the order was counter balanced. Session one was the sham control without tDCS or rTMS. Session two involved cathodal tDCS with sham rTMS. Session three involved rTMS with sham tDCS. Session four was the combination of cathodal tDCS and rTMS(tDCS-rTMS). Cathodal tDCS was applied at 1 mA, and 1200 rTMS pulses were applied at 1 Hz with 90% resting motor threshold (RMT). All stimulation durations lasted for 20 min. RMT was monitored pre- and post-stimulation immediately after finishing the stimulation. Single pulse TMS induced MEP amplitudes were monitored before and after stimulation for 30 min afterwards. ResultsNeither stimulus modality changed the value of RMT. As compared to sham stimulation, MEP amplitudes decreased in other three conditions. MEP amplitudes in tDCS-rTMS were much more inhibited than either tDCS or rTMS alone. Comparison with existing methodsWe could reproduce inhibitory effect of 1 mA cathodal tDCS and 1 Hz rTMS in concordance with previous literature. The novel simultaneous tDCS-rTMS stimulation protocol can induce enhanced excitability change than either tDCS or rTMS. ConclusionsSimultaneous application of cathodal tDCS with low frequency rTMS produces a stronger inhibitory effect.

Revealing the multisensory modulation of auditory stimulus in degraded visual object recognition by dynamic causal modeling

Recent evidence from neurophysiological and functional imaging research has demonstrated that semantically congruent sounds can modulate the identification of a degraded visual object. However, it remains unclear how different integration regions interact with each other when only a visual object was obscured. The present study aimed to elucidate the neural bases of cross-modal functional interactions in degraded visual object recognition. Naturally degraded images and semantically congruent sounds were used in our experiment. Participants were presented with three different modalities of audio-visual stimuli: auditory only (A), degraded visual only (Vd), and simultaneous auditory and degraded visual (AVd). We used conjunction analysis and the classical 'max criterion' to define three audiovisual integration cortical hubs: the visual association cortex, the superior temporal sulcus and the Heschl's gyrus. Dynamic causal modeling (DCM) was then used to infer effective connectivity between these regions. The DCM results revealed that the modulation of an auditory stimulus resulted in increased connectivity from the Heschl's gyrus to the visual association cortex and from the superior temporal sulcus to the visual association cortex. It was shown that the visual association cortex is modulated not only via feedback and top-down connections from higher-order convergence areas but also via lateral feedforward connectivity from the auditory cortex. The present findings give support to interconnected models of cross-modal information integration.

Assessment of conditioned pain modulation in healthy participants and patients with chronic pain: manifestations and implications for pain progression

The purpose of this review is to summarize recent findings on conditioned pain modulation (CPM) in humans with a focus on methodology, factors modulating CPM, and the potential for CPM as a clinical marker for pain progression. CPM can be evoked by combining different stimulus modalities with good reliability; sequential CPM effects are stable over time with limited carryover effects. Optimism and pain catastrophizing might influence pain inhibition. Further, studies suggest that the CPM effect can be improved by gabapentinoids, transcranial direct current stimulation to cortical structures, and exercise and that long-term opioid use might impair CPM in patients with chronic pain. Clinical evidence suggests that preoperative impaired CPM may predict more severe chronic postoperative pain. The effect of pain duration on CPM impairment has been challenged by recent studies. As CPM methodology is optimized, studies are revealing factors that can modulate descending pain inhibitory pathways. Understanding underlying mechanisms of CPM will improve the utility of CPM in a clinical setting and potentially lead to personalized treatments for chronic pain patients.