Perception Of Sensory Stimuli Research Articles

The secondary somatosensory cortex gates mechanical and heat sensitivity

The cerebral cortex is vital for the processing and perception of sensory stimuli. In the somatosensory axis, information is received primarily by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted perception. This suggests that responsiveness to particular somatosensory stimuli occurs in a modality specific fashion and we sought to determine additional cortical substrates. In this work, we identify in a mouse model that inhibition of S2 output increases mechanical and heat, but not cooling sensitivity, in contrast to S1. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and heat sensitivity without affecting motor performance or anxiety. Taken together, we show that S2 is an essential cortical structure that governs mechanical and heat sensitivity.

ASSESSMENT OF SUPERFICIAL SENSITIVITY IN SENIOR POPULATION AFTER PARTICIPATION IN THE TAILORED PROGRAM OF BIOPSYCHOSOCIAL REHABILITATION IN THE LIGHT OF GERONTO-PROPHYLAXIS

Positive attitudes to old age and successful ageing are the trends in contemporary gerontology. Promotion of an active period of old age, the maintenance of cognitive and physical abilities in seniors as well as active participation in various activities and social roles are challenges and tasks for geronto-prophylaxis and psychosocial rehabilitation. The process of ageing, apart from its effect on the body systems and functions has also a marked effect on the perception of sensory stimuli. Sensitivity to touch decreases with age. The aim of the presented study was to show the effect of a tailored program of sensorimotor activation in seniors with different fitness levels on changes in touch sensation in the area of the arms. The main cognitive goal of the presented research project was an assessment of sensory stimuli perception on the completion of the biopsychosocial rehabilitation program using an esthesiometer.The sample included 51 seniors from two care units, aged 77.52 9.51 years. The assessment of superficial sensitivity perception in- volved the two-point discrimination approach using a wheel esthe- siometer (Touch Test-Two Point Discriminator). The study was conducted immediately before and after the application of the rehabilitation program.A significant improvement in sensory perception was noted on the finger bulbs of both hands within the studied senior population, re- gardless of the levels of psychophysical fitness and the social support center where they stayed. The following average values, corresponding to the changes in both hands, were obtained from: 6.6mm to 4.45 in the seniors from the Social Care Unit and from 6.35 to 4.2 in the seniors from the Senior Support (p<0.05). According to the norms for touch sensation (2-point discrimination) for the hand, before the start the level of sensation was satisfactory, below the norm limit, while after rehabilitation this level turned out to be good.The proposed program of biopsychosocial rehabilitation (activation of seniors undergoing hand treatment) fulfilled the settled cognitive and practical goals and was welcomed with great satisfaction and engagement by the beneficiaries In the case of senior rehabilitation the area of geronto-prophylaxis is oriented to the stimulation and improvement of sensory stimuli perception in the hands, using various manual forms of movement.

Dehydrated Drosophila melanogaster track a water plume in tethered flight.

Perception of sensory stimuli can be modulated by changes in internal state to drive contextually appropriate behavior. For example, dehydration is a threat to terrestrial animals, especially to Drosophila melanogaster due to their large surface area to volume ratio, particularly under the energy demands of flight. While hydrated D.melanogaster avoid water cues, while walking, dehydration leads to water-seeking behavior. We show that in tethered flight, hydrated flies ignore a water stimulus, whereas dehydrated flies track a water plume. Antennal occlusions eliminate odor and water plume tracking, whereas inactivation of moist sensing neurons in the antennae disrupts water tracking only upon starvation and dehydration. Elimination of the olfactory coreceptor eradicates odor tracking while leaving water-seeking behavior intact in dehydrated flies. Our results suggest that while similar hygrosensory receptors may be used for walking and in-flight hygrotaxis, the temporal dynamics of modulating the perception of water vary with behavioral state.

Voluntary Actions Modulate Perception and Neural Representation of Action-Consequences in a Hand-Dependent Manner.

Evoked neural activity in sensory regions and perception of sensory stimuli are modulated when the stimuli are the consequence of voluntary movement, as opposed to an external source. It has been suggested that such modulations are due to motor commands that are sent to relevant sensory regions during voluntary movement. However, given the anatomical-functional laterality bias of the motor system, it is plausible that the pattern of such behavioral and neural modulations will also exhibit a similar bias, depending on the effector triggering the stimulus (e.g., right/left hand). Here, we examined this issue in the visual domain using behavioral and neural measures (fMRI). Healthy participants judged the relative brightness of identical visual stimuli that were either self-triggered (using right/left hand button presses), or triggered by the computer. Stimuli were presented either in the right or left visual field. Despite identical physical properties of the visual consequences, we found stronger perceptual modulations when the triggering hand was ipsi- (rather than contra-) lateral to the stimulated visual field. Additionally, fMRI responses in visual cortices differentiated between stimuli triggered by right/left hand. Our findings support a model in which voluntary actions induce sensory modulations that follow the anatomical-functional bias of the motor system.

Mapping GPR88-Venus illuminates a novel role for GPR88 in sensory processing.

GPR88 is an orphan G-protein coupled receptor originally characterized as a striatal-enriched transcript and is a potential target for neuropsychiatric disorders. At present, gene knockout studies in the mouse have essentially focused on striatal-related functions and a comprehensive knowledge of GPR88 protein distribution and function in the brain is still lacking. Here, we first created Gpr88-Venus knock-in mice expressing a functional fluorescent receptor to fine-map GPR88 localization in the brain. The receptor protein was detected in neuronal soma, fibers and primary cilia depending on the brain region, and remarkably, whole-brain mapping revealed a yet unreported layer-4 cortical lamination pattern specifically in sensory processing areas. The unique GPR88 barrel pattern in L4 of the somatosensory cortex appeared 3 days after birth and persisted into adulthood, suggesting a potential function for GPR88 in sensory integration. We next examined Gpr88 knockout mice for cortical structure and behavioral responses in sensory tasks. Magnetic resonance imaging of live mice revealed abnormally high fractional anisotropy, predominant in somatosensory cortex and caudate putamen, indicating significant microstructural alterations in these GPR88-enriched areas. Further, behavioral analysis showed delayed responses in somatosensory-, visual- and olfactory-dependent tasks, demonstrating a role for GPR88 in the integration rather than perception of sensory stimuli. In conclusion, our data show for the first time a prominent role for GPR88 in multisensory processing. Because sensory integration is disrupted in many psychiatric diseases, our study definitely positions GPR88 as a target to treat mental disorders perhaps via activity on cortical sensory networks.

Stimulus Presentation at Specific Neuronal Oscillatory Phases Experimentally Controlled with tACS: Implementation and Applications.

In recent years, it has become increasingly clear that both the power and phase of oscillatory brain activity can influence the processing and perception of sensory stimuli. Transcranial alternating current stimulation (tACS) can phase-align and amplify endogenous brain oscillations and has often been used to control and thereby study oscillatory power. Causal investigation of oscillatory phase is more difficult, as it requires precise real-time temporal control over both oscillatory phase and sensory stimulation. Here, we present hardware and software solutions allowing temporally precise presentation of sensory stimuli during tACS at desired tACS phases, enabling causal investigations of oscillatory phase. We developed freely available and easy to use software, which can be coupled with standard commercially available hardware to allow flexible and multi-modal stimulus presentation (visual, auditory, magnetic stimuli, etc.) at pre-determined tACS-phases, opening up a range of new research opportunities. We validate that stimulus presentation at tACS phase in our setup is accurate to the sub-millisecond level with high inter-trial consistency. Conventional methods investigating the role of oscillatory phase such as magneto-/electroencephalography can only provide correlational evidence. Using brain stimulation with the described methodology enables investigations of the causal role of oscillatory phase. This setup turns oscillatory phase into an independent variable, allowing innovative, and systematic studies of its functional impact on perception and cognition.

The role of inhibition in the generation of reliable spike sequences

Coordinated spiking of neuronal populations underlies the perception of sensory stimuli, the planning of movement, and the acquisition of new memories. In the hippocampus and the entorhinal cortex, groups of neurons are transiently activated as an animal traverses its environment. The sequential patterns generated by these neurons depend, not only on environmental cues, but can also be generated reliably in the absence of these cues. Such patterning depends on the temporal and the spatial distribution of inhibition. It has been hypothesized that inhibitory interneurons corral principal neurons into transiently synchronous ensembles that encode sensory information and sub-serve behavior. The goal of this study is to demonstrate a link between the topology of the inhibitory sub-network and the dynamics of its constituent neurons that, in turn, support the generation of reliable sequences of spiking activity. An understanding of structure-dynamics relationships in complex networks is often challenging because of the formidable dimensionality of the system and the inherent non-linear properties of neurons and synapses that constitute the network. In an earlier study [1] we established a relationship between a structural property of the network, its colorings (a proper vertex coloring of a network is one that assigns different colors to nodes that are directly connected to each other), and the dynamics it constrains. Competitive inhibitory interactions ensure that neurons associated with the same color generate spikes in approximate synchrony. Further we showed that the description of network dynamics based on its coloring comes with a fortuitous benefit. We used the coloring of the inhibitory sub-network as a tool to construct a space in which the distance between excitatory neurons is defined not by the length of the synaptic path connecting those neurons but by the similarity of the inhibitory input they receive. In this reconfigured space, the seemingly high-dimensional dynamics of networks of randomly connected excitatory and inhibitory neurons reliably forms a series of orthogonally propagating waves, a predictable and simple pattern where synchronous ensembles of excitatory neurons are successively recruited. The coloring constrains the identity of inhibitory neurons that spike synchronously. However, it does not impose any constraints on the order in which synchronous groups are recruited. The propensity of a particular group of neurons to spike can be attributed to slow temporal processes such as adaptive changes in the calcium concentration within the cell and slow oscillatory drive over time scales comparable to that of theta oscillations that are observed in the hippocampus and the entorhinal cortex. In this study we systematically vary the topology of the network (exemplified by it's coloring) and the timescale of slow temporal processes to understand how the two interact to construct reliable sequences of activity.

Interpreting Stress Responses during Routine Toxicity Studies

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic-pituitary-adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article-related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias. This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies: In-life Procedures (Section 3), Nervous System (Section 4), Endocrine System (Section 5), Reproductive System (Section 6), Clinical Pathology (Section 7), and Immune System (Section 8). The paper concludes (Section 9) with a brief discussion on Minimizing Stress-Related Effects (9.1.), and a final section explaining why Parameters routinely measured are appropriate for assessing the role of stress in toxicology studies (9.2.).

Multisensory integration mechanisms during aging

The rapid demographical shift occurring in our society implies that understanding of healthy aging and age-related diseases is one of our major future challenges. Sensory impairments have an enormous impact on our lives and are closely linked to cognitive functioning. Due to the inherent complexity of sensory perceptions, we are commonly presented with a complex multisensory stimulation and the brain integrates the information from the individual sensory channels into a unique and holistic percept. The cerebral processes involved are essential for our perception of sensory stimuli and becomes especially important during the perception of emotional content. Despite ongoing deterioration of the individual sensory systems during aging, there is evidence for an increase in, or maintenance of, multisensory integration processing in aging individuals. Within this comprehensive literature review on multisensory integration we aim to highlight basic mechanisms and potential compensatory strategies the human brain utilizes to help maintain multisensory integration capabilities during healthy aging to facilitate a broader understanding of age-related pathological conditions. Further our goal was to identify where further research is needed.

Subthalamic Deep Brain Stimulation Modulates Small-Fiber Dependent Sensory Thresholds in Parkinson's Disease (P02.234)

Objective: The aim of this study was to evaluate the changes induced by deep brain stimulation in the perception of sensory stimuli, either noxious or innocuous, mediated by small or large nerve fibers Background The effects of deep brain stimulation of the subthalamic nucleus on non-motor symptoms of PD have been rarely investigated. Among these, sensory disturbances, including chronic pain, are frequent symptoms in these patients. Design/Methods: Sensory detection and pain thresholds were assessed in 25 PD patients in ON- or OFF-stimulation and OFF-medication condition. The relationship between the changes induced by surgery on quantitative sensory testing, spontaneous pain and motor abilities were studied. Quantitative sensory test results obtained in PD patients were compared to those of age-matched healthy subjects. Results: Pain was present in 72% of patients before vs. 36% after surgery (p=0.019). In the ON-stimulation condition, there was an increased sensitivity to innocuous thermal stimuli, but reduced sensitivity to mechanical or thermal pain. Moreover, thermal pain rating decreased when the stimulator was turned on. Compared to healthy subjects, PD patients had an increased sensitivity to innocuous thermal stimuli and mechanical pain, but a reduced sensitivity to innocuous mechanical stimuli. In addition, they had increased pain rating when painful thermal stimuli were applied, particularly in OFF-stimulation condition. Motor improvement positively correlated with changes in heat and warm thresholds. Conclusions: Subthalamic nucleus deep brain stimulation contributes to relieve pain associated with PD and modulates specifically small fiber mediated sensations. Disclosure: Dr. Ciampi De Andrade has nothing to disclose. Dr. Lefaucheur has nothing to disclose. Dr. Galhardoni has nothing to disclose. Dr. Ferreira has nothing to disclose. Dr. de Paiva has nothing to disclose. Dr. Bohr-Seng-Shu has nothing to disclose. Dr. Alvarenga has nothing to disclose. Dr. Myczkowski has nothing to disclose. Dr. Marcolin has nothing to disclose. Dr. de Siqueira has nothing to disclose. Dr. Fonoff has nothing to disclose. Dr. Barbosa has nothing to disclose. Dr. Teixeira has nothing to disclose.

Subthalamic deep brain stimulation modulates small fiber–dependent sensory thresholds in Parkinson’s disease

The effects of deep brain stimulation of the subthalamic nucleus on nonmotor symptoms of Parkinson’s disease (PD) rarely have been investigated. Among these, sensory disturbances, including chronic pain (CP), are frequent in these patients. The aim of this study was to evaluate the changes induced by deep brain stimulation in the perception of sensory stimuli, either noxious or innocuous, mediated by small or large nerve fibers. Sensory detection and pain thresholds were assessed in 25 PD patients all in the off-medication condition with the stimulator turned on or off (on- and off-stimulation conditions, respectively). The relationship between the changes induced by surgery on quantitative sensory testing, spontaneous CP, and motor abilities were studied. Quantitative sensory test results obtained in PD patients were compared with those of age-matched healthy subjects. Chronic pain was present in 72% of patients before vs 36% after surgery (P=.019). Compared with healthy subjects, PD patients had an increased sensitivity to innocuous thermal stimuli and mechanical pain, but a reduced sensitivity to innocuous mechanical stimuli. In addition, they had an increased pain rating when painful thermal stimuli were applied, particularly in the off-stimulation condition. In the on-stimulation condition, there was an increased sensitivity to innocuous thermal stimuli but a reduced sensitivity to mechanical or thermal pain. Pain provoked by thermal stimuli was reduced when the stimulator was turned on. Motor improvement positively correlated with changes in warm detection and heat pain thresholds. Subthalamic nucleus deep brain stimulation contributes to relieve pain associated with PD and specifically modulates small fiber–mediated sensations.

Product perception from sensory stimuli: the case of vacuum cleaner

This paper discusses the importance of consideration of different sensory stimuli in the perception of the product. So we conducted an experiment that examined whether there is a difference between the perception of sensory stimuli from artificially isolated. The result is an analysis of the different sensory modalities, relating them to product an between them.

Nerve blocks: Psychophysics of spinal cord stimulation

Even after 30 years in clinical use, the mechanism of pain relief with spinal cord stimulation (SCS) is incompletely understood. There is some experimental evidence that alterations in the perception of sensory stimuli may be involved. We studied the effects that SCS had on clinical and experimental pain and evaluated the effects stimulation had on non-painful sensations. Nine chronic pain patients receiving spinal cord stimulation were studied. Patients were evaluated in two sessions. Medications and stimulation were withheld for at least 4 hours prior to each assessment. The first session evaluated the effect of changing parameters on sensory perception. Three parameters were altered; stimulus intensity (voltage), stimulus duration (pulse width), and stimulus frequency (pulses per second). The second session examined the effect of SCS on sensory thresholds to innocuous and noxious stimuli over body areas including the area of pain, the areas of altered sensation, and the areas that were pain-free but where paresthesia were induced. Higher frequencies were perceived by the patients as producing a more intense paresthesiae. Increasing either pulse width or intensity resulted in an exponential increase in paresthesia. Further, areas of altered sensation were found to have an increase in sensory and pain perception when stimulation was applied. Strength duration curves were plotted for all patients and chronaxies were calculated. The average chronaxie was found to be 78 microseconds. Frequency was not found to have an affects on the threshold. SCS alters sensory thresholds . The perception of paresthesiae is frequency, pulse width and intrensity dependent. The chronaxie suggest that these effects are mediated through large diameter axons.

Differences in Perception of Sensory Stimuli in Normals: Clinical Relevance

Differences in Perception of Sensory Stimuli in Normals: Clinical Relevance

Role of neocortical association structures in the spatiotemporal organization of brain potentials in children during perception of sensory stimuli of different modalities.

1. Correlation analysis of the EEG showed that in infants in the second year of life the spatiotemporal organization of brain potentials during the reception of information about an object through auditory or visual channels differs and depends not only on the modality of the stimulus but also in its semantic meaning. 2. During the perception of monomodal and polymodal semantically meaningful stimuli, whether words or objects, the greatest increase in the strength of correlations between potentials is found in the left inferior parietal zone. Perception of familiar words and familiar complex stimuli also increases by 2–2.5 times the number of high correlations in the frontal zone of the dominant hemisphere. 3. Synchronization of potentials of the neocortical association areas with those of projection areas of corresponding modality to the stimulus is increased most of all during perception of sensory stimuli of different modalities: For instance, on presentation of verbal stimuli, synchronization of potentials of the inferior parietal and frontal zones with those of the temporal increases and on presentation of objects, synchronization of potentials of the inferior parietal and occipital zones also increases. 4. Both nonspecific shifts and selective“patterns,” reflecting the specific character of the sensory system concerned, take place in the spatio-temporal organization of brain potentials during perception of sensory stimuli.

Brain events underlying detection and recognition of weak sensory signals.

Through the use of a quantitative extension of signal detection theory, the brain events associated with the detection and recognition of weak acoustic signals were examined by recording brain event-related potentials. The early N100 componenet of the event-related potential varied only with detection, whereas the late P300 component varied with both detection and recognition. P300 amplitude accurately predicted recognition performance on a trial-by-trial basis. The results suggest that detection and recognition are partially concurrent processes in perception and demonstrate that the electrocortical events occurring during the perception of sensory stimuli are closely associated with both detection and recognition of these stimuli by the nervous system.