Environmental Sensory Stimuli Research Articles

Multisensory integration by polymodal sensory neurons dictates larval settlement in a brainless cnidarian larva.

Multisensory integration (MSI) combines information from more than one sensory modality to elicit behaviours distinct from unisensory behaviours. MSI is best understood in animals with complex brains and specialized centres for parsing different modes of sensory information, but dispersive larvae of sessile marine invertebrates utilize multimodal environmental sensory stimuli to base irreversible settlement decisions on, and most lack complex brains. Here, we examined the sensory determinants of settlement in actinula larvae of the hydrozoan Ectopleura crocea (Cnidaria), which possess a diffuse nerve net. A factorial settlement study revealed that photo-, chemo- and mechanosensory cues each influenced the settlement response in a complex and hierarchical manner that was dependent on specific combinations of cues, an indication of MSI. Additionally, sensory gene expression over development peaked with developmental competence to settle, which in actinulae, requires cnidocyte discharge. Transcriptome analyses also highlighted several deep homological links between cnidarian and bilaterian mechano-, chemo-, and photosensory pathways. Fluorescent in situ hybridization studies of candidate transcripts suggested cellular partitioning of sensory function among the few cell types that comprise the actinula nervous system, where ubiquitous polymodal sensory neurons expressing putative chemo- and photosensitivity interface with mechanoreceptive cnidocytes. We propose a simple multisensory processing circuit, involving polymodal chemo/photosensory neurons and mechanoreceptive cnidocytes, that is sufficient to explain MSI in actinulae settlement. Our study demonstrates that MSI is not exclusive to complex brains, but likely predated and contextualized their evolution.

Cilia in the Striatum Mediate Timing-Dependent Functions

Almost all brain cells contain cilia, antennae-like microtubule-based organelles. Yet, the significance of cilia, once considered vestigial organelles, in the higher-order brain functions is unknown. Cilia act as a hub that senses and transduces environmental sensory stimuli to generate an appropriate cellular response. Similarly, the striatum, a brain structure enriched in cilia, functions as a hub that receives and integrates various types of environmental information to drive appropriate motor response. To understand cilia’s role in the striatum functions, we used loxP/Cre technology to ablate cilia from the dorsal striatum of male mice and monitored the behavioral consequences. Our results revealed an essential role for striatal cilia in the acquisition and brief storage of information, including learning new motor skills, but not in long-term consolidation of information or maintaining habitual/learned motor skills. A fundamental aspect of all disrupted functions was the “time perception/judgment deficit.” Furthermore, the observed behavioral deficits form a cluster pertaining to clinical manifestations overlapping across psychiatric disorders that involve the striatum functions and are known to exhibit timing deficits. Thus, striatal cilia may act as a calibrator of the timing functions of the basal ganglia-cortical circuit by maintaining proper timing perception. Our findings suggest that dysfunctional cilia may contribute to the pathophysiology of neuro-psychiatric disorders, as related to deficits in timing perception.

Unexpected Motherhood-Triggered Hearing Loss in the Two-Pore Channel (TPC) Mutant Mouse.

Calcium signaling is crucial for many physiological processes and can mobilize intracellular calcium stores in response to environmental sensory stimuli. The endolysosomal two-pore channel (TPC), regulated by the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP), is one of the key components in calcium signaling. However, its role in neuronal physiology remains largely unknown. Here, we investigated to what extent the acoustic thresholds differed between the WT mice and the TPC KO mice. We determined the thresholds based on the auditory brainstem responses (ABRs) at five frequencies (between 4 and 32 kHz) and found no threshold difference between the WT and KO in virgin female mice. Surprisingly, in lactating mothers (at P9–P10), the thresholds were higher from 8 to 32 kHz in the TPC KO mice compared to the WT mice. This result indicates that in the TPC KO mice, physiological events occurring during parturition altered the detection of sounds already at the brainstem level, or even earlier.

Food Consciousness Intervention Improves Interoceptive Sensitivity and Expression of Exteroception in Women.

The perception of the body’s internal state (interoception) and the perception and processing of environmental sensory stimuli (exteroception) act together to modulate adaptive behaviour, including eating behaviour, and are related to bodyweight control. This study evaluated the impact of the Food and Nutrition Education Program with Sensory and Cognitive Exercises on interoceptive sensitivity and on the expression of exteroceptive perception in women who experienced difficulty in controlling their body weight. Thirty-seven women were randomized into two groups and evaluated at two moments: before and after the intervention or before and after a 3- to 4-week waiting period. A heartbeat tracking task was used for interoception evaluation. Participants were asked to write a text describing three foods after tasting them for exteroception evaluation. After the intervention, the participants showed an increase in interoceptive sensitivity, and an increase in the expression of exteroceptive stimuli perception through a semantic assessment of their writing related to the tasting experience. In addition, the results point to a possible connection between the mechanisms governing interoception and exteroception. This work brings important contributions to the search for strategies capable of promoting the perception and integration of physiological and environmental stimuli in food consumption.

Unrewarding experience with a novel environment modulates olfactory response in the host-searching behavior of parasitic wasps

Generalist insects, which utilize various food resources from various environments, must make decisions to locate resources using novel environmental sensory stimuli when they arrive in a new habitat. In addition to the innate response repertoire, such decision using novel stimuli can include an experience-based process. Here, we showed that the generalist parasitic wasp Aphidius gifuensis altered its olfactory responses after exposure to nonnatal habitat environments, i.e., host plants of aphids. In our laboratory experiments, overnight exposure of female wasps to nonnatal broad bean plants reduced their olfactory preference for uninfested bean plants and induced an olfactory preference for host-infested plants over uninfested plants of both broad bean and wheat. The decrease in olfactory preference for uninfested plants was not observed in wasps with overnight exposure to their natal wheat plants. In addition, the olfactory preference for uninfested wheat plants over uninfested bean plants was not observed without previous rewarding experience (oviposition) on the natal wheat plants prior to the overnight exposure to uninfested bean plants. These results suggest that a certain period of unrewarding experience (residency without host finding) on nonnatal plants promoted emigration from the unrewarded environment and increased the wasp’s response to olfactory cues from host-infested plants of both species. This study shows negative experience with uninfested plants plays a key role in host-searching behavior and habitat (host plant) selection in the wasp.

Olfactory and Neuromodulatory Signals Reverse Visual Object Avoidance to Approach in Drosophila

Behavioral reactions of animals to environmental sensory stimuli are sometimes reflexive and stereotyped but can also vary depending on contextual conditions. Engaging in active foraging or flight provokes a reversal in the valence of carbon dioxide responses from aversion to approach in Drosophila [1, 2], whereas mosquitoes encountering this same chemical cue show enhanced approach toward a small visual object [3]. Sensory plasticity in insects has been broadly attributed to the action of biogenic amines, which modulate behaviors such as olfactory learning, aggression, feeding, and egg laying [4-14]. Octopamine acts rapidly upon the onset of flight to modulate the response gain of directionally selective motion-detecting neurons in Drosophila [15]. How the action of biogenic amines might couple sensory modalities to each other or to locomotive states remains poorly understood. Here, we use a visual flight simulator [16] equipped for odor delivery [17] to confirm that flies avoid a small contrasting visual object in odorless air [18] but that the same animals reverse their preference to approach in the presence of attractive food odor. An aversive odor does not reverse object aversion. Optogenetic activation of either octopaminergic neurons or directionally selective motion-detecting neurons that express octopamine receptors elicits visual valence reversal in the absence of odor. Our results suggest a parsimonious model in which odor-activated octopamine release excites the motion detection pathway to increase the saliency of either a small object or a bar, eliciting tracking responses by both visual features.

Increase in Mutual Information During Interaction with the Environment Contributes to Perception.

Perception and motor interaction with physical surroundings can be analyzed by the changes in probability laws governing two possible outcomes of neuronal activity, namely the presence or absence of spikes (binary states). Perception and motor interaction with the physical environment are partly accounted for by a reduction in entropy within the probability distributions of binary states of neurons in distributed neural circuits, given the knowledge about the characteristics of stimuli in physical surroundings. This reduction in the total entropy of multiple pairs of circuits in networks, by an amount equal to the increase of mutual information, occurs as sensory information is processed successively from lower to higher cortical areas or between different areas at the same hierarchical level, but belonging to different networks. The increase in mutual information is partly accounted for by temporal coupling as well as synaptic connections as proposed by Bahmer and Gupta (Front. Neurosci. 2018). We propose that robust increases in mutual information, measuring the association between the characteristics of sensory inputs’ and neural circuits’ connectivity patterns, are partly responsible for perception and successful motor interactions with physical surroundings. The increase in mutual information, given the knowledge about environmental sensory stimuli and the type of motor response produced, is responsible for the coupling between action and perception. In addition, the processing of sensory inputs within neural circuits, with no prior knowledge of the occurrence of a sensory stimulus, increases Shannon information. Consequently, the increase in surprise serves to increase the evidence of the sensory model of physical surroundings

Cerebral effects of music during isometric exercise: An fMRI study.

A block-design experiment was conducted using fMRI to examine the brain regions that activate during the execution of an isometric handgrip exercise performed at light-to-moderate-intensity in the presence of music. Nineteen healthy adults (7 women and 12 men; Mage = 24.2, SD = 4.9 years) were exposed to an experimental condition (music [MU]) and a no-music control condition (CO) in a randomized order within a single session. Each condition lasted for 10 min and participants were required to execute 30 exercise trials (i.e., 1 trial = 10 s exercise + 10 s rest). Attention allocation, exertional responses, and affective changes were assessed immediately after each condition. The BOLD response was compared between conditions to identify the combined effects of music and exercise on neural activity. The findings indicate that music reallocated attention toward task-unrelated thoughts (d = 0.52) and upregulated affective arousal (d = 0.72) to a greater degree when compared to a no-music condition. The activity of the left inferior frontal gyrus (lIFG) also increased when participants executed the motor task in the presence of music (F = 24.65), and a significant negative correlation was identified between lIFG activity and perceived exertion for MU (limb discomfort: r = -0.54; overall exertion: r = -0.62). The authors hypothesize that the lIFG activates in response to motor tasks that are executed in the presence of environmental sensory stimuli. Activation of this region might also moderate processing of interoceptive signals - a neurophysiological mechanism responsible for reducing exercise consciousness and ameliorating fatigue-related symptoms.

Posturografia em idosos com distúrbios vestibulares e quedas

Introdução: A posturografia estática e dinâmica tem sido usada para analisar a habilidade de idosos com disfunção vestibular em manter o equilíbrio corporal em diferentes condições de conflitos sensoriais. O objetivo do exame é quantificar a velocidade de oscilação e o deslocamento do centro de pressão nas condições de conflitos visual, somatossensorial e interação visuo-vestibular, e o limite de estabilidade. Objetivo: Analisar a literatura referente ao controle do equilíbrio corporal em idosos com distúrbios vestibulares por meio de posturografia computadorizada estática e dinâmica. Métodos: Revisão nas bases de dados LILACS, EMBASE, MEDLINE, Scielo, Cochrane, ISI Web of Knowledge e bibliotecas virtuais de teses e dissertações, utilizando as palavras-chave “Idoso”, “Equilíbrio Postural”, “Avaliação”, “Controle Postural”, “Quedas”, “Posturografia”, “Vestibular” e/ou “Tontura” de publicações dos últimos vinte anos. Resultados: Há vários modelos de posturografias que mensuram as respostas posturais e o risco de quedas em indivíduos idosos, perante os diferentes estímulos sensoriais, incluindo a tecnologia de realidade virtual. Os idosos com desequilíbrio corporal, tontura, e/ou com histórico de quedas apresentam pior desempenho que idosos sem queixas, sem histórico de quedas e indivíduos mais jovens. Conclusão: A posturografia é uma valiosa ferramenta para análise quantitativa do controle postural, permitindo a identificação das condições sensoriais nas quais os idosos vestibulopatas apresentam maior instabilidade.

The Role of Sensory Gating in the Racism/Blood Pressure Relationship

African Americans bear a disproportionate burden of hypertension with racism postulated as a unique stressor contributing to the noted disparities. Epidemiological studies have found differences in the prevalence of hypertension among African Americans based on the amount of perceived racism reported, and experimental studies have shown increased cardiovascular reactivity to racially-aversive stressors. A difference in individual response to racial stressors may create subgroups of African Americans at highest risk for hypertension and its complications. Although sensory gating is the brain’s capacity to selectively regulate its sensitivity to environmental sensory stimuli, scant research has been done regarding the role of sensory gating in the stress response, and no research has explored sensory gating with racial stressors. To address this gap, we examined whether P50 sensory gating was associated with cardiovascular and central nervous system responses to an experimentally-induced racial stressor among 15 African Americans. A paired-click paradigm was administered prior to the experimental condition, which involved exposure to a neutral and then a racially-aversive photo stimulus. Participants with weak gating showed a significant within-subjects decrease in alpha-band activity when viewing the racially aversive stimulus and had significantly decreased alpha activity when viewing the aversive stimuli compared to participants with strong gating. Increased cardiovascular reactivity occurred with the aversive stimulus, and gender differences were noted. A gating effect on cardiovascular reactivity could not be determined given the small sample size and the fact that few men qualified as having ‘good’ gating. Although subjects reported no conscious awareness of distress when viewing the racially-aversive stimulus, both cardiovascular and central nervous system reactions occurred, with the responses varying based on the level of sensory gating. These results suggest sensory gating as a potential physiologic factor that may influence the relationship between perceived racial stressors and health outcomes.

Sensory filtering phenomenology in PTSD

Disrupted sensory filtering, or problems with suppressing irrelevant environmental sensory stimuli, has been reported in individuals with posttraumatic stress disorder (PTSD). However, the relationship of sensory filtering deficits to specific PTSD symptoms versus an association with general trauma exposure is unclear. These relationships were examined by administering self-report measures of trauma exposure, PTSD, and sensory gating phenomenology to undergraduate participants with PTSD (n=32), with trauma history but without PTSD (n=144), and with minimal trauma history (n=153). Subjects with PTSD reported greater filtering disruption than individuals in the trauma only and low trauma groups, who did not differ. Individuals endorsing reexperiencing and numbing symptoms, and females endorsing hypervigilance, reported disrupted sensory filtering phenomenology. These results suggest that impaired filtering differentiates between individuals with PTSD symptoms and asymptomatic individuals exposed to multiple traumas and low-trauma controls.

Peripheral, autonomic regulation of locus coeruleus noradrenergic neurons in brain: putative implications for psychiatry and psychopharmacology.

In 1946 von Euler identified the major transmitter of sympathetic nerve fibers, norepinephrine (NE), and about a decade later Vogt (1954) provided the first evidence that NE may also serve as a neurotransmitter in the central nervous system (CNS). Since that time, a literal explosion in CNS neurotransmitter research has taken place involving histological, biochemical, physiological, pharmacological and clinical investigations. Yet, it is only now that we are beginning to understand the biological function of NE in brain, in particular because of recent advances regarding the physiology and regulation of NE neurons in locus coeruleus (LC), a bilateral pontine structure with a uniquely wide-spread terminal network reaching throughout the neuroaxis and in primates accounting for about 70% of all brain NE. Recently, the neurobiology of the LC noradrenergic network was extensively reviewed by Foote et al. (1983), and its implication in vigilance as well as global orientation of behavior towards imperative, environmental sensory stimuli was outlined. Yet, more recent information regarding the peripheral, autonomic regulation of LC neurons in brain provides fundamentally new biological aspects on behavior and mental function which seem to allow a more integrated view of the rôle of brain NE in the overall function of the individual than previously understood. The purpose of this review is to summarize these findings and, furthermore, to outline some putative implications for psychiatry and neuropsychopharmacology.(ABSTRACT TRUNCATED AT 250 WORDS)

An ecological approach to mechanisms determining individual differences in perception.

In 1982 Satow proposed four hypothetical properties determining mechanisms of individual differences in perceptions; these were supported by results of a factor analysis of responses to a 58-item check list. Present work confirmed the four properties (intense sensitivity, temporal sensitivity, sensory-motor reactivity, and possible range of total stimuli), and obtained a property, preference for intense and prolonged stimuli, from a principal component analysis of data from a 60-item list given to 316 subjects. The 60-item list is a revised version of the 58-item list which asked subjects about their subjective sensitiveness and preferences for environmental sensory stimuli (visual, auditory, olfactory, and tactile). Within subjects relationships among these properties are interindependent, since for individuals correlations of factor-score estimates between pairs of these properties were near zero. This interindepedence supported a model of four hypothetical types of individuals, explaining the individual differences on the grounds of the relations among the properties.

Nonparallel relationship between tolerance and sensitivity for visual and aditory environmental stimuli

In this paper, the four types which concern the relationship between sensory tolerance and sensiveness for environmental sensory stimuli were proposed theoretically. These hypothetical four types were supported by the results obtained from factor analytical approach. The two checklists were compiled in place of actual psycho-physical measurements in order to apply the factor analysis. The first version of the checklist was applied to the 100 male subjects, and the second version to the 229 male subjects. The eight factors which resulted from the first version of the list were the following: A) General sensitivity, B) Temporal sensitivity, C) Orientation to the strong and prolonged sensory (the two factors were included in this label), D) Orientation to the weak stimuli (the two factors were included also), E) Activation level, F) Abnormal temporal sensitivity. The six factors were obtained from the second version of the list. Five factors of these six, s were the same as to each of above mentioned A to E. The other one was G) Sensory-motor reactivity. The four factors, A to D, which resulted from two large sample of the subjects, and from the different checklists, were the sensory properties common to inter-moeal senses. The factors A and B related to “the culture free behavior”, and the factor C and D related to “the culture bound behavior”. These four factors gave support to the existence of the four types.