Cross-modal Stimulation Research Articles

Wireless electrocochleography in awake chinchillas: A model to study crossmodal modulations at the peripheral level

The discovery and development of electrocochleography (ECochG) in animal models has been fundamental for its implementation in clinical audiology and neurotology. In our laboratory, the use of round-window ECochG recordings in chinchillas has allowed a better understanding of auditory efferent functioning. In previous works, we gave evidence of the corticofugal modulation of auditory-nerve and cochlear responses during visual attention and working memory. However, whether these cognitive top-down mechanisms to the most peripheral structures of the auditory pathway are also active during audiovisual crossmodal stimulation is unknown. Here, we introduce a new technique, wireless ECochG to record compound-action potentials of the auditory nerve (CAP), cochlear microphonics (CM), and round-window noise (RWN) in awake chinchillas during a paradigm of crossmodal (visual and auditory) stimulation. We compared ECochG data obtained from four awake chinchillas recorded with a wireless ECochG system with wired ECochG recordings from six anesthetized animals. Although ECochG experiments with the wireless system had a lower signal-to-noise ratio than wired recordings, their quality was sufficient to compare ECochG potentials in awake crossmodal conditions. We found non-significant differences in CAP and CM amplitudes in response to audiovisual stimulation compared to auditory stimulation alone (clicks and tones). On the other hand, spontaneous auditory-nerve activity (RWN) was modulated by visual crossmodal stimulation, suggesting that visual crossmodal simulation can modulate spontaneous but not evoked auditory-nerve activity. However, given the limited sample of 10 animals (4 wireless and 6 wired), these results should be interpreted cautiously. Future experiments are required to substantiate these conclusions. In addition, we introduce the use of wireless ECochG in animal models as a useful tool for translational research.

Cross-modal facilitation of auditory discrimination in a frog.

Stimulation in one sensory modality can affect perception in a separate modality, resulting in diverse effects including illusions in humans. This can also result in cross-modal facilitation, a process where sensory performance in one modality is improved by stimulation in another modality. For instance, a simple sound can improve performance in a visual task in both humans and cats. However, the range of contexts and underlying mechanisms that evoke such facilitation effects remain poorly understood. Here, we demonstrated cross-modal stimulation in wild-caught túngara frogs, a species with well-studied acoustic preferences in females. We first identified that a combined visual and seismic cue (vocal sac movement and water ripple) was behaviourally relevant for females choosing between two courtship calls in a phonotaxis assay. We then found that this combined cross-modal stimulus rescued a species-typical acoustic preference in the presence of background noise that otherwise abolished the preference. These results highlight how cross-modal stimulation can prime attention in receivers to improve performance during decision-making. With this, we provide the foundation for future work uncovering the processes and conditions that promote cross-modal facilitation effects.

Controlled audio-visual stimulation for anxiety reduction

Background and objectiveRecent clinical data suggest that 75% of patients undergoing surgery are anxious, despite pharmacological measures to relieve anxiety. As an alternative to the administration of drugs, the scientific literature reports the relevant psychophysiological effects of auditory and visual stimulation in reducing preoperative anxiety. The main objective of this study is the development of a portable computer-controlled device for the simultaneous combined administration of audio-visual stimuli and the evaluation of this device through the collection and the statistical analysis of psychophysiological parameters strictly related to the state of anxiety. MethodsA new algorithmic approach for the real-time association of sounds and colours is proposed and implemented in a low-cost architectural platform. The combined administration of auditory and visual stimuli is tested on 220 subjects undergoing dental surgery; in particular, psychophysiological parameters are collected and evaluated in four experimental conditions, in order to demonstrate the efficacy of cross-modal stimulation (auditory and visual) compared to non-pharmacological treatments based on monomodal stimuli (auditory or visual). ResultsNon-parametric statistical techniques applied to the recorded experimental data show that the experimental conditions considered significantly differ. Pairwise comparisons between experimental groups show that the combined administration of sounds and colors significantly reduces the level of anxiety, systolic blood pressure and heart rate to a greater extent than monomodal stimulation. ConclusionThe study demonstrates the potential benefits of a device for the combined administration of auditory and visual stimuli. The developed device has proven effective in reducing preoperative anxiety levels, becoming a serious candidate for non-pharmacological therapies. The study also encourages a deeper investigation of models capable of better capturing the potential of cross-modal stimulation, maximizing the desired effects (relaxation, arousal) on patients awaiting specific medical treatments.

Excitatory Crossmodal Input to a Widespread Population of Primary Sensory Cortical Neurons.

Crossmodal information processing in sensory cortices has been reported in sparsely distributed neurons under normal conditions and can undergo experience- or activity-induced plasticity. Given the potential role in brain function as indicated by previous reports, crossmodal connectivity in the sensory cortex needs to be further explored. Using perforated whole-cell recording in anesthetized adult rats, we found that almost all neurons recorded in the primary somatosensory, auditory, and visual cortices exhibited significant membrane-potential responses to crossmodal stimulation, as recorded when brain activity states were pharmacologically down-regulated in light anesthesia. These crossmodal cortical responses were excitatory and subthreshold, and further seemed to be relayed primarily by the sensory thalamus, but not the sensory cortex, of the stimulated modality. Our experiments indicate a sensory cortical presence of widespread excitatory crossmodal inputs, which might play roles in brain functions involving crossmodal information processing or plasticity.

Repeated but not incremental training enhances cross-modal recalibration.

Sensory representations are constantly realigned. For instance, in the ventriloquism aftereffect, short exposure to audiovisual stimuli with a consistent spatial disparity results in an adjustment of auditory spatial representations. Here we tested whether repeated audiovisual training over several sessions enhances recalibration in the ventriloquism aftereffect. One group of participants (n = 16) received incremental training in which the presented degree of audiovisual spatial disparity increased over the course of 3 days, whereas a second group (n = 16) was constantly exposed to the largest disparity during all three sessions (constant training). Within each session, a significant ventriloquism aftereffect was observed in both groups. However, the size of the final ventriloquism aftereffect was larger in the constant group, due to an increase over days that was not evident in the incremental group. These findings replicated results obtained in two prestudies that either used a smaller sample size or included constant training only. Taken together, our findings provide strong evidence that recalibration effects are retained and consolidated between sessions, contrary to the intuitive assumption that natural audiovisual stimulation outside the laboratory would immediately overwrite recalibration. Repeated training seems to be particularly effective for consistent changes in cross-modal stimulation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Spatial receptive field shift by preceding cross-modal stimulation in the cat superior colliculus.

It has been known for some time that sensory information of one type can bias the spatial perception of another modality. However, there is a lack of evidence of this occurring in individual neurons. In the present study, we found that the spatial receptive field of superior colliculus multisensory neurons could be dynamically shifted by a preceding stimulus in a different modality. The extent to which the receptive field shifted was dependent on both temporal and spatial gaps between the preceding and following stimuli, as well as the salience of the preceding stimulus. This result provides a neural mechanism that could underlie the process of cross-modal spatial calibration. Psychophysical studies have shown that the different senses can be spatially entrained by each other. This can be observed in certain phenomena, such as ventriloquism, in which a visual stimulus can attract the perceived location of a spatially discordant sound. However, the neural mechanism underlying this cross-modal spatial recalibration has remained unclear, as has whether it takes place dynamically. We explored these issues in multisensory neurons of the cat superior colliculus (SC), a midbrain structure that involves both cross-modal and sensorimotor integration. Sequential cross-modal stimulation showed that the preceding stimulus can shift the receptive field (RF) of the lagging response. This cross-modal spatial calibration took place in both auditory and visual RFs, although auditory RFs shifted slightly more. By contrast, if a preceding stimulus was from the same modality, it failed to induce a similarly substantial RF shift. The extent of the RF shift was dependent on both temporal and spatial gaps between the preceding and following stimuli, as well as the salience of the preceding stimulus. A narrow time gap and high stimulus salience were able to induce larger RF shifts. In addition, when both visual and auditory stimuli were presented simultaneously, a substantial RF shift toward the location-fixed stimulus was also induced. These results, taken together, reveal an online cross-modal process and reflect the details of the organization of SC inter-sensory spatial calibration.

Effects of maternal anxiety and depression on fetal neuro-development

Fetal development is affected by maternal mental health with research indicating that maternal anxiety and depression are co-morbid; nevertheless differential effects on the fetus have been found. This study examines, prenatally, effects of maternal stress, anxiety and depression on fetal eye-blink reactions to experimental sound and light stimulation. Two groups of singleton fetuses (mean 32-weeks gestation) were examined using 4D ultrasound: a control group (N = 14, 7 female) with no stimulation and an experimental group (N = 21, 13 female) exposed to experimental sound, light and cross-modal stimulation. For both groups ultrasound scans were performed and fetal eye-blink was assessed. Mothers completed the Hospital-Anxiety-and-Depression Scale and the Perceived-Stress Scale. Analysis was carried out using Poisson mixed effects modelling. Fetal eye-blink rate during experimental stimulation was significantly and differentially associated with maternal mental health with a 20% increase of fetal eye-blink rate for each unit increase in anxiety score (p = 0.02) and a decrease of 21% of eye blink rate for each unit of increase in depression score (p = 0.02). Sound stimulation but not light stimulation significantly affected blink-rate with fetuses habituating to the stimuli (p < 0.001). Limitations are the relatively small number of fetuses and that a follow up after birth is essential to establish potential long-term effects. Of clinical importance is the finding that although fetuses are affected by maternal mental health in general here we demonstrate, using eye-blink-rate during stimulation as measure of neuro-development, that fetuses are differentially affected by maternal anxiety and depression with anxiety increasing and depression decreasing fetal reactivity significantly.

Auditory motion does not modulate spiking activity in the middle temporal and medial superior temporal visual areas.

The integration of multiple sensory modalities is a key aspect of brain function, allowing animals to take advantage of concurrent sources of information to make more accurate perceptual judgments. For many years, multisensory integration in the cerebral cortex was deemed to occur only in high-level "polysensory" association areas. However, more recent studies have suggested that cross-modal stimulation can also influence neural activity in areas traditionally considered to be unimodal. In particular, several human neuroimaging studies have reported that extrastriate areas involved in visual motion perception are also activated by auditory motion, and may integrate audiovisual motion cues. However, the exact nature and extent of the effects of auditory motion on the visual cortex have not been studied at the single neuron level. We recorded the spiking activity of neurons in the middle temporal (MT) and medial superior temporal (MST) areas of anesthetized marmoset monkeys upon presentation of unimodal stimuli (moving auditory or visual patterns), as well as bimodal stimuli (concurrent audiovisual motion). Despite robust, direction selective responses to visual motion, none of the sampled neurons responded to auditory motion stimuli. Moreover, concurrent moving auditory stimuli had no significant effect on the ability of single MT and MST neurons, or populations of simultaneously recorded neurons, to discriminate the direction of motion of visual stimuli (moving random dot patterns with varying levels of motion noise). Our findings do not support the hypothesis that direct interactions between MT, MST and areas low in the hierarchy of auditory areas underlie audiovisual motion integration.

Cross-modal codification of images with auditory stimuli: a language for the visually impaired ?

In this study we describe a methodology to realize visual images cognition in the broader sense, by a cross-modal stimulation through the auditory channel. An original algorithm of conversion from bi-dimensional images to sounds has been established and tested on several subjects. Our results show that subjects where able to discriminate with a precision of 95\% different sounds corresponding to different test geometric shapes. Moreover, after brief learning sessions on simple images, subjects where able to recognize among a group of 16 complex and never-trained images a single target by hearing its acoustical counterpart. Rate of recognition was found to depend on image characteristics, in 90% of the cases, subjects did better than choosing at random. This study contribute to the understanding of cross-modal perception and help for the realization of systems that use acoustical signals to help visually impaired persons to recognize objects and improve navigation

Measuring multisensory integration: from reaction times to spike counts

A neuron is categorized as “multisensory” if there is a statistically significant difference between the response evoked, e.g., by a crossmodal stimulus combination and that evoked by the most effective of its components separately. Being responsive to multiple sensory modalities does not guarantee that a neuron has actually engaged in integrating its multiple sensory inputs: it could simply respond to the stimulus component eliciting the strongest response in a given trial. Crossmodal enhancement is commonly expressed as a proportion of the strongest mean unisensory response. This traditional index does not take into account any statistical dependency between the sensory channels under crossmodal stimulation. We propose an alternative index measuring by how much the multisensory response surpasses the level obtainable by optimally combining the unisensory responses, with optimality defined as probability summation under maximal negative stochastic dependence. The new index is analogous to measuring crossmodal enhancement in reaction time studies by the strength of violation of the “race model inequality’, a numerical measure of multisensory integration. Since the new index tends to be smaller than the traditional one, neurons previously labeled as “multisensory’ may lose that property. The index is easy to compute and it is sensitive to variability in data.

Crossmodal attentional control sets between vision and audition

The interplay between top-down and bottom-up factors in attentional selection has been a topic of extensive research and controversy amongst scientists over the past two decades. According to the influential contingent capture hypothesis, a visual stimulus needs to match the feature(s) implemented into the current attentional control sets in order to be automatically selected. Recently, however, evidence has been presented that attentional control sets affect not only visual but also crossmodal selection. The aim of the present study was therefore to establish contingent capture as a general principle of multisensory selection. A non-spatial interference task with bimodal (visual and auditory) distractors and bimodal targets was used. The target and the distractors were presented in close temporal succession. In order to perform the task correctly, the participants only had to process a predefined target feature in either of the two modalities (e.g., colour when vision was the primary modality). Note that the additional crossmodal stimulation (e.g., a specific sound when hearing was the secondary modality) was not relevant for the selection of the correct response. Nevertheless, larger interference effects were observed when the distractor matched both the stimulus of the primary as well as the secondary modality and this pattern was even stronger if vision was the primary modality than if audition was the primary modality. These results are therefore in line with the crossmodal contingent capture hypothesis. Both visual and auditory early processing seem to be affected by top-down control sets even beyond the spatial dimension.

Visual and cross-modal cues increase the identification of overlapping visual stimuli in Balint’s syndrome

ABSTRACTIntroduction: Cross-modal interactions improve the processing of external stimuli, particularly when an isolated sensory modality is impaired. When information from different modalities is integrated, object recognition is facilitated probably as a result of bottom-up and top-down processes. The aim of this study was to investigate the potential effects of cross-modal stimulation in a case of simultanagnosia. Method: We report a detailed analysis of clinical symptoms and an 18F-fluorodeoxyglucose (FDG) brain positron emission tomography/computed tomography (PET/CT) study of a patient affected by Balint’s syndrome, a rare and invasive visual–spatial disorder following bilateral parieto-occipital lesions. An experiment was conducted to investigate the effects of visual and nonvisual cues on performance in tasks involving the recognition of overlapping pictures. Four modalities of sensory cues were used: visual, tactile, olfactory, and auditory. Results: Data from neuropsychological tests showed the presence of ocular apraxia, optic ataxia, and simultanagnosia. The results of the experiment indicate a positive effect of the cues on the recognition of overlapping pictures, not only in the identification of the congruent valid-cued stimulus (target) but also in the identification of the other, noncued stimuli. All the sensory modalities analyzed (except the auditory stimulus) were efficacious in terms of increasing visual recognition. Conclusions: Cross-modal integration improved the patient’s ability to recognize overlapping figures. However, while in the visual unimodal modality both bottom-up (priming, familiarity effect, disengagement of attention) and top-down processes (mental representation and short-term memory, the endogenous orientation of attention) are involved, in the cross-modal integration it is semantic representations that mainly activate visual recognition processes. These results are potentially useful for the design of rehabilitation training for attentional and visual–perceptual deficits.

Commentary: Top-down and bottom-up modulation of pain-induced oscillations.

Commentary: Top-down and bottom-up modulation of pain-induced oscillations.

Event-related potential evidence for a dynamic (re-)weighting of somatotopic and external coordinates of touch during visual-tactile interactions.

The localization of touch in external space requires the remapping of somatotopically represented tactile information into an external frame of reference. Several recent studies have highlighted the role of posterior parietal areas for this remapping process, yet its temporal dynamics are poorly understood. The present study combined cross-modal stimulation with electrophysiological recordings in humans to trace the time course of tactile spatial remapping during visual-tactile interactions. Adopting an uncrossed or crossed hand posture, participants made speeded elevation judgments about rare vibrotactile stimuli within a stream of frequent, task-irrelevant vibrotactile events presented to the left or right hand. Simultaneous but spatially independent visual stimuli had to be ignored. An analysis of the recorded event-related potentials to the task-irrelevant vibrotactile stimuli revealed a somatotopic coding of tactile stimuli within the first 100ms. Between 180 and 250ms, neither an external nor a somatotopic representation dominated, suggesting that both coordinates were active in parallel. After 250ms, tactile stimuli were coded in a somatotopic frame of reference. Our results indicate that cross-modal interactions start before the termination of tactile spatial remapping, that is within the first 100ms. Thereafter, tactile stimuli are represented simultaneously in both somatotopic and external spatial coordinates, which are dynamically (re-)weighted as a function of processing stage.

The effect of early visual deprivation on the neural bases of multisensory processing.

Developmental vision is deemed to be necessary for the maturation of multisensory cortical circuits. Thus far, this has only been investigated in animal studies, which have shown that congenital visual deprivation markedly reduces the capability of neurons to integrate cross-modal inputs. The present study investigated the effect of transient congenital visual deprivation on the neural mechanisms of multisensory processing in humans. We used functional magnetic resonance imaging to compare responses of visual and auditory cortical areas to visual, auditory and audio-visual stimulation in cataract-reversal patients and normally sighted controls. The results showed that cataract-reversal patients, unlike normally sighted controls, did not exhibit multisensory integration in auditory areas. Furthermore, cataract-reversal patients, but not normally sighted controls, exhibited lower visual cortical processing within visual cortex during audio-visual stimulation than during visual stimulation. These results indicate that congenital visual deprivation affects the capability of cortical areas to integrate cross-modal inputs in humans, possibly because visual processing is suppressed during cross-modal stimulation. Arguably, the lack of vision in the first months after birth may result in a reorganization of visual cortex, including the suppression of noisy visual input from the deprived retina in order to reduce interference during auditory processing.

Age-related hearing loss increases cross-modal distractibility

Recent electrophysiological studies have provided evidence that changes in multisensory processing in auditory cortex cannot only be observed following extensive hearing loss, but also in moderately hearing-impaired subjects. How the reduced auditory input affects audio–visual interactions is however largely unknown. Here we used a cross-modal distraction paradigm to investigate multisensory processing in elderly participants with an age-related high-frequency hearing loss as compared to young and elderly subjects with normal hearing. During the experiment, participants were simultaneously presented with independent streams of auditory and visual input and were asked to categorize either the auditory or visual information while ignoring the other modality. Unisensory sequences without any cross-modal input served as control conditions to assure that all participants were able to perform the task. While all groups performed similarly in these unisensory conditions, hearing-impaired participants showed significantly increased error rates when confronted with distracting cross-modal stimulation. This effect could be observed in both the auditory and the visual task. Supporting these findings, an additional regression analysis indicted that the degree of high-frequency hearing loss significantly modulates cross-modal visual distractibility in the auditory task. These findings provide new evidence that already a moderate sub-clinical hearing loss, a common phenomenon in the elderly population, affects the processing of audio–visual information.

A Psychophysical and Steady-State EEG Study of Cross-Modal Integration with Temporal and Spatial Manipulation of Auditory and Tactile Stimulation.

Event Abstract Back to Event A Psychophysical and Steady-State EEG Study of Cross-Modal Integration with Temporal and Spatial Manipulation of Auditory and Tactile Stimulation. Timothy W. Budd1*, Elle K. Gillard1 and Justin R. Timora1 1 University of Newcastle, School of Psychology, Australia In order to establish a reliable representation of our natural environment, the human brain must integrate sensory information both within and across separate modalities (Giani et al., 2012). Combining information across modalities, or multisensory integration, may enhance detection of sensory signals within each modality by providing complementary information. Aims: The current study aimed to determine the effect of cross-modal correspondence of temporal and spatial physical characteristics for multisensory auditory and vibrotactile stimulation, on psychophysical and steady-state EEG measures of multisensory integration. Method: The current study also examined whether cross-modal stimulation to only one side of the body (i.e. unilateral) alters psychophysical and steady-state EEG measures of multisensory integration relative to cross-modal stimulation of both sides of the body (i.e. bilateral). Results: The results suggest that correspondence of temporal physical characteristics (e.g. amplitude modulation) for cross-modal stimuli enhances neural responses but potentially disrupts rather than enhances perceptual processing. Moreover, correspondence of spatial characteristics (e.g. side of the body stimulated) does not influence the psychophysical and steady-state EEG measures of multisensory integration. Unilateral and bilateral stimulation were also found to differentially influence both psychophysical and steady-state EEG measures of multisensory integration. A potential inverse relationship between steady-state EEG measures and perceptual sensitivity was also observed. Keywords: multisensory integration, Steady State EEG, auditory, vibrotactile, Temporal and Spatial Processing Conference: Australasian Society for Psychophysiology, Inc, Coffs Harbour, Australia, 26 Nov - 28 Nov, 2014. Presentation Type: Poster Topic: Psychophysiology Citation: Budd TW, Gillard EK and Timora JR (2014). A Psychophysical and Steady-State EEG Study of Cross-Modal Integration with Temporal and Spatial Manipulation of Auditory and Tactile Stimulation.. Conference Abstract: Australasian Society for Psychophysiology, Inc. doi: 10.3389/conf.fnhum.2014.216.00015 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Oct 2014; Published Online: 02 Dec 2014. * Correspondence: Dr. Timothy W Budd, University of Newcastle, School of Psychology, Ourimbah, New South Wales, 2258, Australia, bill.budd@newcastle.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Timothy W Budd Elle K Gillard Justin R Timora Google Timothy W Budd Elle K Gillard Justin R Timora Google Scholar Timothy W Budd Elle K Gillard Justin R Timora PubMed Timothy W Budd Elle K Gillard Justin R Timora Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A Neural Network Model of Ventriloquism Effect and Aftereffect

Presenting simultaneous but spatially discrepant visual and auditory stimuli induces a perceptual translocation of the sound towards the visual input, the ventriloquism effect. General explanation is that vision tends to dominate over audition because of its higher spatial reliability. The underlying neural mechanisms remain unclear. We address this question via a biologically inspired neural network. The model contains two layers of unimodal visual and auditory neurons, with visual neurons having higher spatial resolution than auditory ones. Neurons within each layer communicate via lateral intra-layer synapses; neurons across layers are connected via inter-layer connections. The network accounts for the ventriloquism effect, ascribing it to a positive feedback between the visual and auditory neurons, triggered by residual auditory activity at the position of the visual stimulus. Main results are: i) the less localized stimulus is strongly biased toward the most localized stimulus and not vice versa; ii) amount of the ventriloquism effect changes with visual-auditory spatial disparity; iii) ventriloquism is a robust behavior of the network with respect to parameter value changes. Moreover, the model implements Hebbian rules for potentiation and depression of lateral synapses, to explain ventriloquism aftereffect (that is, the enduring sound shift after exposure to spatially disparate audio-visual stimuli). By adaptively changing the weights of lateral synapses during cross-modal stimulation, the model produces post-adaptive shifts of auditory localization that agree with in-vivo observations. The model demonstrates that two unimodal layers reciprocally interconnected may explain ventriloquism effect and aftereffect, even without the presence of any convergent multimodal area. The proposed study may provide advancement in understanding neural architecture and mechanisms at the basis of visual-auditory integration in the spatial realm.

Potential application of cross-modal stimulation for neurorehabilitation: The relatedness of performance on tasks measuring cognitive processes subserved by similar prefrontal substrates

Rehabilitating people with prefrontal functional impairment has always been challenging. This study examined whether there are functional relationships between prefrontal processes subserved by similar neural regions. The aim was to shed light on the therapeutic potential of training one function to effect changes in another function, a phenomenon called cross-modal stimulation in neurorehabilitation. The study examined risky decision-making by people of high or low odour-identification ability because both processes are subserved by the orbitofrontal regions. This question was examined in a sample of women (n = 44) with high or low odour-identification ability, classified according to their performance on the Odour Identification Test. Their risky decision-making was measured by the Risky Gains Task. The women with better odour-identification ability made more risky decisions. However, there was no such difference on another cognitive task (Choice RT and Suppress Test), the processing of which involves frontal substrates other than the orbitofrontal region. These findings provide preliminary insight into the phenomenon that performance on tests of prefrontal functions could relate to each other if the functions share similar prefrontal substrates.

Crossmodal stimulation influences communication in visual-somatosensory cortical networks of the Brown Norway rat

Processing of most action goals and complete perception of the environment, like spatial localization of events, require integration of information from different sensory systems. The classical idea of a hierarchical sensory organization is challenged by recent evidence from both human and primate work showing that multisensory processing is already taking place in primary sensory cortices. However, the mechanisms underlying this multisensory processing and the role of primary sensory cortices in crossmodal communication and oscillatory coupling remain largely unknown. Congruent and incongruent uni- and bimodal visual (light spot) and tactile (whisker deflection) stimulation was performed simultaneously with extracellular multielectrode recordings in the primary visual (V1) and somatosensory (S1, barrel field) neocortices of adolescent Brown Norway rats in vivo. Tactile stimulation led after 10–30 ms to a phase-locked, large amplitude response in the contralateral S1 that is accompanied by prominent, layer-specific sinks and sources. Additionally, non-phase-locked oscillations were induced in different frequency ranges. Visual stimulation alone did not change the amplitude of oscillations compared to baseline activity in the contralateral S1, but reset the phase of ongoing oscillatory activity. Because of the visual impact in the S1, bimodal congruent stimulation led to an increase of the evoked response and changed the timing of amplitude enhancement of oscillations. These data indicate that networks in the barrel cortex are modulated by crossmodal visual input.