Series Of Stimuli Research Articles

Histamine and histidine decarboxylase: Immunomodulatory functions and regulatory mechanisms

Histamine is a bioactive monoamine that is synthesized by the enzymatic activity of histidine decarboxylase (HDC) in basophils, mast cells, gastric enterochromaffin‐like (ECL) cells and histaminergic neuronal cells. Upon a series of cellular stimuli, these cells release stored histamine, which elicits allergies, inflammation, and gastric acid secretion and regulates neuronal activity. Recent studies have shown that certain other types of myeloid lineage cells also produce histamine with HDC induction under various pathogenic stimuli. Histamine has been shown to play a series of pathophysiological roles by modulating immune and inflammatory responses in a number of disease conditions, whereas the mechanistic aspects underlying induced HDC expression remain elusive. In the present review, we summarize the current understanding of the regulatory mechanism of Hdc gene expression and the roles played by histamine in physiological contexts as well as pathogenic processes. We also introduce a newly developed histaminergic cell‐monitoring transgenic mouse line (Hdc‐BAC‐GFP) that serves as a valuable experimental tool to identify the source of histamine and dissect upstream regulatory signals.

Support from a TMS/MEP study for a direct link between positive/negative stimuli and approach/avoidance tendencies

Previous behavioral studies using stimulus-response compatibility tasks have shown that people are faster to carry out instructed approach/avoidance responses to positive/negative stimuli. This result has been taken as evidence that positive/negative stimulus valence directly activates a tendency to approach/avoid, which in turn, facilitates execution of instructed approach/avoidance behavior. In these studies, however, it cannot be excluded that the results reflect a purely semantic link between stimulus valence and instructed responses. According to this alternative interpretation, positive/negative stimuli do not elicit an approach/avoidance tendency, but instead they interact with the positive/negative valence of the instructed responses, and in this way, produce the observed compatibility effect. To circumvent this possible disadvantage of compatibility tasks, we used a novel method for the measurement of early action tendencies: TMS induced MEPs. In two experiments, participants were first trained to abduct the index finger to approach and the thumb to avoid. Then, they observed a series of positive and negative stimuli. Each stimulus was followed by a TMS pulse (at 400 ms post-stimulus onset) and MEPs were measured continuously on the muscles of both fingers. These observation trials were randomly intermixed with response trials, in which neutral stimuli were presented and participants were instructed to approach/avoid the stimuli. In Experiment 1, participants received clear visual feedback on the outcome of their response in the response trials. In Experiment 2, we omitted this feedback to test whether it was necessary for the effect to occur. The results indicated higher MEPs for the approach/avoidance finger after positive/negative stimuli in Experiment 1 but not in Experiment 2. Analyses on the data aggregated over both experiments suggest that the visual feedback was necessary for stimulus valence to elicit action tendencies. Taken together, the results are in line with the results of behavioral studies with compatibility tasks, suggesting that stimulus valence directly elicits specific action tendencies already at 400 ms but they indicate that clear visual feedback is necessary for this effect to occur.

Cardiac response to stimulation and stress in the American alligator (Alligator mississippiensis)

Abstract Previous descriptions of the direction (tachycardia versus bradycardia), magnitude, and duration of the cardiac stimulation/stress response of the American alligator (Alligator mississippiensis) have been contradictory. Superficial EKG leads were used to quantify heart rate while presenting a graded series of stimuli to a cohort of 5 sub-adult alligators. Only tachycardic responses were recorded. Stress (manual restraint and transport) induced a nearly 3-fold increase over the resting heart rate (∼17 bpm), which decreased only 7 bpm over 40 minutes in a stimulus-free environment. Lower-level stimulation (i.e., exposure to room light) produced a significantly smaller response than did higher-level stimulation (i.e., physical contact), both responses were transitory, lasting approximately 120 s.

Nocebo hyperalgesia can be induced by classical conditioning without involvement of expectancy.

Influential theoretical accounts take the position that classical conditioning can induce placebo effects through conscious expectancies. In the current study two different conditioning procedures (hidden and open) were used to separate expectancy from conditioning in order to reveal the role of expectancy in the formation of nocebo hyperalgesia. Eighty-seven healthy females were randomly assigned to three groups (hidden conditioning, open conditioning, and control). Participants were selected according to the Fear of Pain Questionnaire scores and assigned to two subgroups: high and low level of fear of pain (trait). They received electrocutaneous pain stimuli preceded by either an orange or blue color. During the conditioning phase, one color was paired with pain stimuli of moderate intensity (control stimuli) and the other color was paired with pain stimuli of high intensity (nocebo stimuli) in both hidden and open conditioning groups. Only participants in the open conditioning group were informed about this association, however just before the testing phase the expectancy of hyperalgesia induced in this way was withdrawn. In the control group, both colors were followed by control pain stimuli. During the testing phase all participants received a series of stimuli of the same intensity, regardless of the preceding color. Participants rated pain intensity, expectancy of pain intensity and fear (state). We found that nocebo hyperalgesia was induced by hidden rather than open conditioning. The hidden conditioning procedure did not produce conscious expectancies related to pain. Nocebo hyperalgesia was induced in participants with low and high fear of pain and there was no difference in the magnitude of the nocebo effect between both groups. Nocebo hyperalgesia was not predicted by the fear of upcoming painful stimuli.

Presynaptic Calcium Channel Open Probability and Changes in Calcium Influx Throughout the Action Potential Determined Using AP-Waveforms.

Action potentials arriving at a nerve terminal activate voltage-gated calcium channels and set the electrical driving force for calcium entry which affects the amount and duration of neurotransmitter release. During propagation, the duration, amplitude, and shape of action potentials often changes. This affects calcium entry, and can cause large changes in neurotransmitter release. Here, we have used a series of amplitude and area matched stimuli to examine how the shape and amplitude of a stimulus affect calcium influx at a presynaptic nerve terminal in the mammalian brain. We identify fundamental differences in calcium entry following calcium channel activation by a standard voltage jump vs. an action potential-like stimulation. We also tested a series of action potential-like stimuli with the same amplitude, duration, and stimulus area, but differing in their rise and decay times. We find that a stimulus that matches the rise and decay times of a physiological action potential produces a calcium channel response that is optimized over a range of peak amplitudes. Next, we determined the relative number of calcium channels that are active at different times during an action potential, which is important in the context of how local calcium domains trigger neurotransmitter release. We find the depolarizing phase of an AP-like stimulus only opens ~20% of the maximum number of calcium channels that can be activated. Channels continue to activate during the falling phase of the action potential, with peak calcium channel activation occurring near 0 mV. Although less than 25% of calcium channels are active at the end of the action potential, these calcium channels will generate a larger local calcium concentration that will increase the release probability for nearby vesicles. Determining the change in open probability of presynaptic calcium channels, and taking into account how local calcium concentration also changes throughout the action potential are both necessary to fully understand how the action potential triggers neurotransmitter release.

EEG Correlates of Voluntary and Involuntary Mental Attention in the Non-stationary Research Mode

We continued the study of EEG correlates of cognitive states with different contributions of sensory and mental attention in the non-stationary research mode. Tasks for sensory and mental attention were presented in series of 80 or 40 trials. Each trial contained two types of stimuli: visually presented words concretized the variants of the task; the presentation of images or a blank screen indicated the beginning of memorization or recall (imagination). Along with the tasks, a series of similar stimuli (words and blank screen) was presented, but the subjects were not asked to perform any tasks. In the latter case, the subjects passively observed irrelevant visual stimuli and, apparently, were withdrawn to their inner world (mind-wandering state). This condition is characterized by a specific EEG pattern, which differs from the patterns observed at rest and during cognitive tasks involving sensory and mental attention. Repetition of visual stimuli in the non-stationary research mode of mental attention has a masking effect on the dynamics of EEG synchronization in the α2 range. This masking effect occurs only if cognitive tasks are triggered by relevant sensory stimuli, but not by irrelevant stimuli. The findings support the opinion that synchronization in the α range is an essential sign of mental attention. A possible EEG pattern specific for voluntary figurative mental attention was also observed; this specific pattern includes different directions of changes in high-frequency EEG bands (β2 and γ) in the anterior and posterior areas of the cortex.

Use of penile plethysmography in the court: A review of practices in Canada, the United Kingdom and the United States.

Penile plethysmography (PPG) is an objective measure of male sexual arousal in response to the presentation of a series of erotic and neutral stimuli. This measure is now widely recognized as the most reliable means of objectively measuring male sexual arousal to specific stimuli. Many clinicians and researchers consider PPG to be a vital contribution to the assessment and treatment of adult men with paraphilic interests and men who have committed sex crimes. PPG contributes to the clinical assessment of paraphilic interests, appraisal of risk of recidivism, and provides an objective measurement of changes in sexual arousal in response to treatment. There is strong support for the utility of PPG within clinical and legal contexts. This article addresses ways in which PPG has been utilized in the courts as part of expert clinical opinion. History of its use, details regarding admissibility in court, and case law are explored within the legal systems of Canada, the UK and the USA. Support for the inclusion of PPG as expert evidence is provided and judicial misunderstandings on the rationale for PPG use and its clinical utility in forensic assessments are discussed.

Problem Solving as a Path to Comprehension

The ability to read, write and manipulate complex mathematical expressions is assumed in most user interfaces for programs designed for authoring, collaboration and reasoning in mathematics. However, little is actually known about how people cognitively process and integrate information when solving complex mathematical problems. In this paper eye-tracking was used to examine how people read and integrate information from mathematical symbols and complex formula, with eye fixations being used as a measure of their current focus of attention. We studied two groups of subjects: mathematically “Expert” and “Non-Expert”. Each participant in the study was presented with a series of stimuli in the form of mathematical problems and their eyes were tracked as they worked through the problems mentally. We discuss the performance differences between Experts and Non-Experts, and between subjects who completed problems Correctly and Incorrectly. From these examinations, we were able to demonstrate differences in both the comprehension and problem-solving approach of the two groups, with the results suggesting that what information is selected, and how, is responsible for a particularly large portion of success in solving such problems. This study has implications in mathematical software usability and accessibility, in particular for educational software, as comprehension of mathematical notation and formalism is often inherent in the implementation of structured mathematical software interfaces.

Population spatial frequency tuning in human early visual cortex

Neurons within early visual cortex are selective for basic image statistics, including spatial frequency. However, these neurons are thought to act as band-pass filters, with the window of spatial frequency sensitivity varying across the visual field and across visual areas. Although a handful of previous functional (f)MRI studies have examined human spatial frequency sensitivity using conventional designs and analysis methods, these measurements are time consuming and fail to capture the precision of spatial frequency tuning (bandwidth). In this study, we introduce a model-driven approach to fMRI analyses that allows for fast and efficient estimation of population spatial frequency tuning (pSFT) for individual voxels. Blood oxygen level-dependent (BOLD) responses within early visual cortex were acquired while subjects viewed a series of full-field stimuli that swept through a large range of spatial frequency content. Each stimulus was generated by band-pass filtering white noise with a central frequency that changed periodically between a minimum of 0.5 cycles/degree (cpd) and a maximum of 12 cpd. To estimate the underlying frequency tuning of each voxel, we assumed a log-Gaussian pSFT and optimized the parameters of this function by comparing our model output against the measured BOLD time series. Consistent with previous studies, our results show that an increase in eccentricity within each visual area is accompanied by a drop in the peak spatial frequency of the pSFT. Moreover, we found that pSFT bandwidth depends on eccentricity and is correlated with the pSFT peak; populations with lower peaks possess broader bandwidths in logarithmic scale, whereas in linear scale this relationship is reversed.NEW & NOTEWORTHY Spatial frequency selectivity is a hallmark property of early visuocortical neurons, and mapping these sensitivities gives us crucial insight into the hierarchical organization of information within visual areas. Due to technical obstacles, we lack a comprehensive picture of the properties of this sensitivity in humans. Here, we introduce a new method, coined population spatial frequency tuning mapping, which circumvents the limitations of the conventional neuroimaging methods, yielding a fuller visuocortical map of spatial frequency sensitivity.

Opinión pública y encuestas de opinión en España

Este trabajo, en su organización y contenido, responde a una serie de estímulos que deseo hacer explícitos. El estímulo inmediato ha sido la necesidad de tener que relatar a un grupo de colegas venezolanos la historia de las encuestas en España. Por otra parte, y al filo de la coyuntura, he tratado de formalizar una serie de respuestas a cuestiones que, en los últimos ocho años, se me han planteado sobre el tema de las encuestas y en contextos diferentes: los medios de comunicación, el aula universitaria o la asesoría profesional.Repasando notas y fichas, he vuelto a visualizar a los muy diversos interlocutores de discusiones sobre los estudios de opinión. El producto de esos diálogos in absentia es este trabajo. Y a ellos invoco como justificación. Hay secciones poco hilvanadas y temas importantes que se tratan fugazmente. Puesto que no se trataba de hacer algo original, sino de contar cosas que otros han hecho o dicho, he sentido la presión de tener que hablar de todo un poco. Y, sobre todo, he sentido la necesidad de no poder contar la historia de las encuestas en España sin articular previamente un discurso, tal vez excesivo, sobre la teoría de la opinión pública y la naturaleza de los sondeos de opinión.

Lie detection using extreme learning machine: A concealed information test based on short‐time Fourier transform and binary bat optimization using a novel fitness function

AbstractLie detection is one of the major challenges that is being faced by the forensic sciences. Identification of lie on the basis of a person's mental behavior is a tedious task. Brain‐computer interface is one such medium which provides a solution to this problem by displaying visual stimuli and recording subject's brain responses. A P300 response is elicited whenever a person comes across a familiar stimuli in a series of rare stimuli. This P300 response is used for the lie detection method. In the proposed concealed information test, acquired signals are preprocessed to discard noise. Then, short‐time Fourier transform method is applied to extract features from the preprocessed electroencephalogram signals. To avoid the curse of dimensionality and to reduce computational overhead, binary bat algorithm is applied, which helps in choosing optimal subset of features. The obtained set of features is given as an input to the extreme learning machine classifier for training of guilty and innocent samples. The performance of the system is assessed using 10‐fold cross‐validation. The resultant accuracy obtained from the proposed lie detection system is 88.3%. The system has provided efficient results in contrast with most of the state‐of‐the‐art lie detection methods.

Effectiveness Of H-Hope Plus Kinesthetic With Virgin Coconut Oil (VCO) On Body Weight In Premature Infants

Background: Prematurity complications in the first year contribute to one million children die and each year around 15 million babies are born prematurely. Prematurity is still a major health problem worldwide. Premature babies with LBW are at risk of developing growth disorders, especially body weight. One intervention that can be given is visual-tactile-kinesthetic stimulation. This stimulation is a stimulus series that provides sensory and motor experiences so that premature babies can show their appropriate growth progress. Objective: To determine the effectiveness of H-HOPE plus kinesthetic with VCO on the growth of premature infants. Methods: This type of experimental design study with pretest-posttest with control group design with independent variables was intervention in the form of H-HOPE plus Kinesthetic with VCO and Kangaroo Mother Care (KMC). The samples in this study were preterm post-treatment infants at Hospital. Sampling uses probability sampling technique with random sampling. The number of samples in this study is 30 respondents with 15 people in the intervention and control groups. Results: The results of giving H-Hope plus kinesthetic and VCO interventions for 14 days in increasing body weight obtained sig value of 0.001 with mean ± SD (612.27 ± 80.82). Conclusion: H-Hope plus kinesthetic with VCO is more effective in increasing body weight.

Self-organization of multiarmed spiral waves in excitable media.

We present an investigation of self-organized multiarmed spiral waves pinned to unexcitable circular obstacles in a thin layer of the excitable Belousov-Zhabotinsky reaction and in simulations using the Oregonator model. The multiarmed waves are initiated by a series of wave stimuli. In the proximity of the obstacle boundary, the wave rotation around the obstacle causes damped oscillations of the wave periods of all spiral arms. The dynamics of wave periods cause the wave velocities as well as the angular displacements between the adjacent arms to oscillate with decaying amplitudes. Eventually, all displacements approach approximately the same stable value so that all arms are distributed evenly around the obstacle. A further theoretical analysis reveals that the temporal dynamics of the angular displacements can be interpreted as underdamped harmonic oscillations. Far from the obstacles, the wave dynamics are less pronounced. The wave period becomes stable very soon after the initiation. When the number of spiral arms increases, the rotation of individual arms slows down but the wave period of the multiarmed spiral waves decreases. Due to their short period, multiarmed spiral waves emerging in the heart potentially result in severe pathological conditions.

Factors shaping vowel perception biases in adults

Vowel discrimination is often asymmetric such that discriminating the same vowel pair is easier in one direction compared to the opposite direction. The Natural Referent Vowel framework interprets these directional asymmetries as a universal bias favoring “focal” vowels (i.e., vowels with prominent spectral peaks formed by the convergence of adjacent formants). The Native Language Magnet model instead interprets asymmetries in terms of a language-specific bias due to distortion of perceptual space around native language vowel prototypes. To test these competing views, Masapollo et al. (2017) compared English- and French-speaking adults’ discrimination of synthetic /u/ variants; this was informative because English /u/ is naturally less focal than French /u/. Their findings revealed asymmetries to be predicted by focalization only; although stimulus limitations may explain the lack of prototype effects. Here, we synthesized a more refined series of vowel stimuli systematically varying in smaller psychophysical steps around the English /u/ and French /u/ prototypes to augment the measurement of focalization and prototype effects. Native English speakers completed a category goodness-rating task followed by an AX-discrimination task using these new variants. Results indicated effects of both focalization and prototype, which are moderated by the size of acoustic intervals along the stimulus series.

An empirical category-ratio scale for evaluating the subjective intensity of noise based on the comparison of estimated magnitudes and categories

In psychophysical studies, the methods of magnitude estimation (ME) and rating scale (RS) are often employed to obtain the subjective intensity of noise. Research interest has usually focused on obtaining precise growth functions to express the relation between subjective and objective magnitudes of stimuli in the ME method, or utilising proper categories for a series of stimuli in the RS method. There have been few studies concerned with the validity of the two direct scaling methods in measuring the subjective intensity of noise. This paper investigated the subjective discomfort caused by noise in the methods of relative magnitude estimation (RME), absolute magnitude estimation (AME), and RS. Forty-two participants were divided into three groups, and each group rated the discomfort caused by 22 noise stimuli at sound pressure levels from 49 to 91 dBA using RME, AME or RS method, respectively. Results indicated that the RS method yields interval scales and the ME method yields logarithmic interval scales for the discomfort of noise, so the sensory continua of noise discomfort could be described in linear relation or power function, depending on the evaluating methods. Based on the empirical data, a category-ratio scale was developed for evaluating the noise discomfort by combining the scales of AME and the scales and verbal descriptors of RS. Equations were also proposed tentatively for noise discomfort to predict the categories from the estimated magnitudes.

The influence of social context on the perception of assistive technology: using a semantic differential scale to compare young adults’ views from the United Kingdom and Pakistan

Background and aim: A Society's view of disability may influence the perception and use of Assistive Technology (AT) products. Semantic cues or cultural coding provide the viewer with a series of visual stimuli to be given or ascribed meaning. Previous research has shown cognitive approaches to visual perception and assignment of meaning vary between diverse cultures. This study reviews the influence of contextual settings on perception, to provide the basis for a debate on the societal perception of communicative content (semantic/meaning) of an AT product; and, the relevance of different cultural cognitive styles. The paper explores, from a cultural viewpoint, the overall understanding of disability internationally.Method: A Semantic Differential (SD) scale was used to obtain views on the image of an attendant wheelchair from nine hundred and ninety-one (991) young adults from the United Kingdom (UK) and Pakistan (PAK), reflecting the individualist and collectivist societies, respectively. This survey follows a previous paper-based study using the same image and protocol. Comparing the two surveys, a consensus of views from the two groups was achieved.Results and conclusion: The responses from the UK group were skewed towards a negative view of disability compared to the Pakistan group. This inferred greater social stigma associated with this AT product in the UK. The combined findings from both surveys provide insights into societal perception of AT products and disability. Areas for future research are suggested, including what visual components of an AT product (graphemes) appear to be associated with positive or negative responses for collectivist and individual societal groups.Implications for rehabilitationAssistive Technology (AT) product designers, academics, professionals and stakeholders need to be aware of challenges which are originated from one's socio-cultural environment. AT products convey certain meanings, semantics, which are interpreted by the society and are subjective to a specific cultural setting.•For the effective communication of meanings and values an AT product relies on the visual clues and design features embedded within the design. However, there have been a limited number of studies reviewing this aspect of product semantics.•The survey and associated testing has highlighted the differences in cultural perception towards AT products and demonstrated the importance of effectively designing the semantic attributes of an AT product as well as its function.•The demonstration of the efficacy of methods within the study for exploring the interpretation of semantic attributes of AT products will help designers and developers better understand the perceptions of individual cultures and societal groups.•A better understanding of different cultures and societies will enable designers and clinicians who specify AT products to reduce AT product abandonment; and, the associated stigma around disability.

Categorization in the Perception of Breathy Voice Quality and Its Relation to Voice Production in Healthy Speakers.

Purpose Previous studies of speech articulation have shown that individuals who can perceive smaller differences between similar-sounding phonemes showed larger contrasts in their productions of those phonemes. Here, a similar relationship was examined between the perception and production of breathy voice quality. Method Twenty females with healthy voices were recruited to participate in both a voice production and a perception experiment. Each participant produced repetitions of a sustained vowel, and acoustic correlates of breathiness were calculated. Identification and discrimination tasks were performed with a series of synthetic stimuli along a breathiness continuum. Categorical boundary location and boundary width were obtained from the identification task as a measurement of perception of breathiness. Spearman's correlation analysis was performed to estimate associations between values of boundary location and width and the acoustic correlates of breathiness from the participants' voices. Results Significant correlations between boundary width (r = -.53 to -.6) and some acoustic correlates were found, but no significant relationships were observed between boundary location and the acoustic correlates. Conclusions Speakers with small boundary widths, which suggest higher perceptual precision in differentiating breathiness, had typical voices that were less breathy, as estimated with acoustic measures, compared to speakers with large boundary widths. Our findings may support a link between perception and production of breathy voice quality. Supplemental Material https://doi.org/10.23641/asha.9808478.

H-Hope Plus Kinesthetic With Vco On Weight And Body Length Of Preterm Infants

<p>Prematurity is still a major health problem worldwide. Premature babies with LBW are at risk of developing growth disorders, especially body weight. Prematurity complications in the first year contribute to one million children die and each year around 15 million babies are born prematurely. One intervention that can be given is visual-tactile-kinesthetic stimulation. This stimulation is a stimulus series that provides sensory and motor experiences so that premature babies can show their appropriate growth progress. This research to determine the effectiveness of H-HOPE plus kinesthetic with VCO on the weight and body length of preterm infants. This type of experimental design study with pretest-posttest with control group design with independent variables was intervention in the form of H-HOPE plus Kinesthetic with VCO and Kangaroo Mother Care (KMC). The samples in this study were preterm infants post Hospital-Care. Sampling used probability sampling technique with random sampling. The number of samples in this study is 30 respondents with 15 people in the intervention and control groups. The results of giving H-Hope plus kinesthetic with VCO interventions for 14 days in increasing weight and body length obtained sig value of 0.001 and 0.009 H-Hope plus kinesthetic with VCO is more effective in increasing weight and body length.<strong></strong></p>

Action priming is linked to visual perception in continuous flash suppression.

Visual prime stimuli can affect the processing of following target stimuli even if their visibility is reduced due to visual masking. Prime visibility depends on the stimulus parameters of the prime and those of the mask. Here we explored the effects of prime stimuli and modulated their visibility by continuous flash suppression (CFS). CFS reduces the visibility of a stimulus presented to one eye by simultaneously presenting a series of high-contrast masking stimuli to the other eye. We manipulated the strength of CFS effects on perception and examined how action priming effects of the masked stimuli varied under the same conditions. Prime visibility was modulated by the contrast of the primes (Experiments 1 and 2), the contrast of the masks (Experiments 2 and 3), and by the stimulus onset asynchrony between prime and target stimuli (all experiments). Surprisingly, action priming effects were modulated by these experimental variables in a parallel way. In addition, individual differences between participants in prime visibility correlated with individual differences in action priming. Our findings suggest that action priming and prime perception depend in similar ways on prime contrast, mask contrast, stimulus onset asynchrony, and individual dispositions in CFS. These findings distinguish CFS from other perceptual suppression techniques, such as backward masking, that allow reducing prime visibility without parallel effects on action priming. Our results corroborate the view that CFS interferes with visual processing at early stages in the cortical hierarchy with similar effects on later processing for perception and action.

P1‐183: FLOW CYTOMETRIC CALCIUM FLUX MEASUREMENT IN ACUTELY‐ISOLATED BRAIN MYELOID CELLS

Neuroinflammation in Alzheimer's disease (AD) is mediated primarily by microglia and brain-infiltrating monocytes/macrophages, collectively called CNS mononuclear phagocytes (CNS-MPs)[1-3]. Effector functions of CNS-MPs are dependent of transient and sustained elevations in intracytosolic calcium (calcium flux)[4, 5]. Understanding the differences in the regulators of calcium flux in subsets of CNS-MPs as well as under homeostatic and neurodegeneration-associated activated states can help identify novel therapeutic strategies for immunomodulation in AD. In this study, we apply a flow-cytometric, ratiometric calcium flux assay to acutely-isolated CNS-MPs to contrast basal and stimulus-evoked calcium flux responses in resident microglia (CD45low) and CNS-macrophages (CD45high) CNS-MPs and in wild-type and AD mouse models (5xFAD). CNS-MPs from wild-type and 5xFAD mice were acutely isolated from adult mice and incubated with CD11b and CD45 flow-cytometric antibodies and Indo-1(30mins). Kinetic flow cytometric assay was performed (over 8 mins) to measure free intracellular calcium at baseline and following a series of immune stimuli: lipopolysaccharide(10uM), interferon gamma(100nM), ATP(10uM), thapsigargin(10uM) and ionomycin(1uM). Dependence of stimulus-evoked responses on Kir2.1 potassium channels were examined using a selective blocker ML133(100uM). FlowJo was used for kinetic and quantitative analyses of data. Acutely-isolated CNS-MPs demonstrated calcium flux in response to immune stimuli and thapsigargin, similar to BV2 microglia, establishing the validity of our flow assay.CD45high macrophages demonstrated higher basal calcium levels compared to CD45low microglia. Microglia showed higher calcium flux in response to all three immune stimuli compared to macrophages. Interferon-gamma response was seen only in microglia (p=0.02) Blockade of Kir2.1 channels significantly increased basal calcium levels in all CD45high macrophages, more evidently from 5xFAD mice (p=0.017). Additionally, there is higher thapsigargin-induced calcium flux (p=0.019) in CD45low microglia from 5xFAD mice as compared to wild-type microglia.