Biology subjects

Spivak, M.

Publications and source records attributed to Spivak, M..

6 recordsLinked to original sources

bioRxiv2025

The effect of two distinct viral-enriched inocula on the immune response and chemical cues in honey bee pupae

The combination of Varroa destructor (Varroa) and the viruses it vectors is a major driver of honey bee (Apis mellifera) colony losses. Hygienic behavior and individual immunity enable bees to cope with some pests and parasites. Hygienic response of adult bees is driven by olfactory cues emanating from diseased brood. In this study, we tested the effect of viral inoculation on the chemical profile and immune response of pupae, independently of Varroa. We injected pupae with various doses of an enriched inocula of either a deformed wing virus (DWV) B-A recombinant or Israeli acute paralysis virus (IAPV) and followed their development and survival for five days. At the end of the five-day period, volatile profiles, viral loads, and expression of seven immune genes were assessed. Both IAPV and the DWV loads increased to equivalent high levels irrespective of the initial dose applied. Notably, greater rates of mortality (60% loss) were observed with the highest IAPV dose when compared to the lowest IAPV dose (15% loss). The DWV inoculum, caused limited mortality but nonetheless inhibited pupae development. The IAPV injected pupae showed evidence of a dose dependent DWV amplification from either a DWV variant in the original IAPV inoculum or from an endogenous source of DWV in the pupae themselves. IAPV-injected pupae had lower expression of immune genes than DWV-injected pupae, suggesting IAPV inhibits the pupae immune response. Overall, among the seven tested immune genes six were upregulated with only vago downregulated, suggesting inhibition of the RNAi pathway following infection. Chemical cues of mock and untreated pupae were similar, but notably different from the virus-injected pupae for both inocula. Our findings show that Varroa-independent virus inoculated pupae produce unique virus-specific chemical cues; the ultimate consequence of such a change might lead to virus specific bee behavioral responses. Authors summaryThis study investigated how two major honey bee viruses, Deformed Wing Virus (DWV) and Israeli Acute Paralysis Virus (IAPV), affect pupae independent of the Varroa mite, which typically spreads them. This study was conducted in the laboratory on incubated pupae isolated from the colony and injected with two viral preparations (inocula). We tested the impact after five-days incubation. The results show that both viruses reach high levels in pupae, though IAPV inoculum proved far more deadly (up to 60% mortality) and appeared to suppress the pupaes immune response, possibly even amplifying co-occurring DWV. While less lethal, the DWV inoculum still inhibited normal development. Interestigly, the virus-infected pupae produced distinct, virus-specific chemical cues--unique volatile profiles different from healthy controls. Since adult honey bees use olfactory cues to detect and remove diseased brood (hygienic behavior), these findings suggest that the viruses themselves generate the "scent of sickness," which could trigger colony-wide behavioral responses and offer a vital target for enhancing the bees natural defenses against these major drivers of colony loss. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/683288v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@18e6203org.highwire.dtl.DTLVardef@c4b6d5org.highwire.dtl.DTLVardef@bf6499org.highwire.dtl.DTLVardef@165b9d1_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2020

2D or Not 2D? An FMRI Study of How Dogs Visually Process Objects

ABSTRACTGiven humans’ habitual use of screens, they rarely consider potential differences when viewing two dimensional (2D) stimuli and real-world versions of dimensional stimuli. Dogs also have access to many forms of screens and touch pads, with owners even subscribing to dog-directed content. Humans understand that 2D stimuli are representations of real-world objects, but do dogs? In canine cognition studies, 2D stimuli are almost always used to study what is normally 3D, like faces, and may assume that both 2D and 3D stimuli are represented in the brain the same way. Here, we used awake fMRI of 15 dogs to examine the neural mechanisms underlying dogs’ perception of two- and three-dimensional objects after the dogs were trained on either a two- or three-dimensional version of the objects. Activation within reward processing regions and parietal cortex of the dog brain to 2D and 3D versions of objects was determined by their training experience, as dogs trained on one dimensionality showed greater activation to the dimension on which they were trained. These results show that dogs do not automatically generalize between two- and three-dimensional stimuli and caution against implicit assumptions when using pictures or videos with dogs.Competing Interest StatementG.B. & M.S. own equity in Dog Star Technologies and developed technology used in some of the research described in this paper. The terms of this arrangement have been reviewed and approved by Emory University in accordance with its conflict of interest policies.View Full Text

animal behavior and cognition↗

bioRxiv2019

Canine sense of quantity: evidence for numerical ratio-dependent activation in parietotemporal cortex

The approximate number system, which supports the rapid estimation of quantity, emerges early in human development and is widespread across species. Neural evidence from both human and non-human primates suggests the parietal cortex as a primary locus of numerical estimation, but it is unclear whether the numerical competencies observed across non-primate species are subserved by similar neural mechanisms. Moreover, because studies with non-human animals typically involve extensive training, little is known about the spontaneous numerical capacities of non-human animals. To address these questions, we examined the neural underpinnings of number perception using awake canine functional magnetic resonance imaging. Dogs passively viewed dot arrays that varied in ratio and, critically, received no task-relevant training or exposure prior to testing. We found evidence of ratio-dependent activation, which is a key feature of the approximate number system, in canine parietotemporal cortex in the majority of dogs tested. This finding is suggestive of a neural mechanism for quantity perception that has been conserved across mammalian evolution.

neuroscience↗

bioRxiv2019

Decoding Odor Mixtures in the Dog Brain: An Awake fMRI Study

In working and practical contexts, dogs rely upon their ability to discriminate a target odor from distracting odors and other sensory stimuli. Few studies have examined odor discrimination using non-behavioral methods or have approached odor discrimination from the dogs perspective. Using awake fMRI in 18 dogs, we examined the neural mechanisms underlying odor discrimination between two odors and a mixture of the odors. Neural activation was measured during the presentation of a target odor (A) associated with a food reward, a distractor odor (B) associated with nothing, and a mixture of the two odors (A+B). Changes in neural activation during the presentations of the odor stimuli in individual dogs were measured over time within three regions known to be involved with odor processing: the caudate nucleus, the amygdala, and the olfactory bulbs. Average activation within the amygdala showed that dogs maximally differentiated between odor stimuli based on the stimulus-reward associations by the first run, while activation to the mixture (A+B) was most similar to the no-reward (B) stimulus. To identify the neural representation of odor mixtures in the dog brain, we used a random forest classifier to compare multilabel (elemental) vs. multiclass (configural) models. The multiclass model performed much better than the multilabel (weighted-F1 0.44 vs. 0.14), suggesting the odor mixture was processed configurally. Analysis of the subset of high-performing dogs based on their brain classification metrics revealed a network of olfactory information-carrying brain regions that included the amygdala, piriform cortex, and posterior cingulate. These results add further evidence for the configural processing of odor mixtures in dogs and suggest a novel way to identify high-performers based on brain classification metrics.

neuroscience↗

bioRxiv2017

Awake fMRI Reveals Covert Arousal in Aggressive Dogs Under Social Resource Threat

Domestic dogs are highly social, and have been shown sensitive not only to the actions of humans and other dogs but to the interactions between them. To examine the canine neurobiological response to observed interactions between a human and another dog, we collected fMRI data from dogs while they watched their owner feed a realistic fake dog or deposit food in a bucket. Given the likelyihood that arousal and affective state may contribute to responses to observed social situations, we examined the relationship between amygdala activation in these two conditions and an independent measure of aggressive temperament from the C-BARQ scale. Dogs rated more aggressive showed significantly higher activation in the fake-dog versus bucket condition. This finding suggests a neurobiological mechanism mediated by the amygdala for dog-directed aggression, especially when their owner interacts with another dog. Such a mechanism may have some parallels to human jealousy. Further, it adds to a growing body of evidence that specific neurobiological responses correlate with canine temperament and can be a predictor of future behavior. We also found evidence that the amygdala response habituates with repeated observed interactions. This suggests value in exposure-based interventions for potentially aggressive dogs.

neuroscience↗

bioRxiv2017

Awake fMRI Reveals Mechanisms of Language Comprehension in Dogs

How do dogs understand human words? At a basic level, understanding would require the discrimination of words from non-words. To determine the mechanisms of such a discrimination, we trained 12 dogs to retrieve two objects based on object names, then probed the neural basis for these auditory discriminations using awake-fMRI. We compared the neural response to these trained words relative to \"oddball\" pseudowords the dogs had not heard before. Consistent with novelty detection, we found greater activation for pseudowords relative to trained words bilaterally in the parietotemporal cortex. To probe the neural basis for representations of trained words, searchlight multivoxel pattern analysis (MVPA) revealed that a subset of dogs had clusters of informative voxels that discriminated between the two trained words. These clusters included the left temporal cortex and amygdala, left caudate nucleus, and thalamus. These results demonstrate that dogs processing of human words utilizes basic processes like novelty detection, and for some dogs, may also include auditory and hedonic representations.

neuroscience↗