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

2019 ◽  
Author(s):  
Ashley Prichard ◽  
Raveena Chhibber ◽  
Jon King ◽  
Kate Athanassiades ◽  
Mark Spivak ◽  
...  
Keyword(s):  
Piriform Cortex ◽  
Brain Regions ◽  
Odor Discrimination ◽  
Neural Representation ◽  
Neural Activation ◽  
Sensory Stimuli ◽  
High Performing ◽  
Odor Processing ◽  
Dog Brain ◽  
Odor Mixtures

AbstractIn 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 dog’s 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.

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

2020 ◽  
Vol 45 (9) ◽  
pp. 833-844
Author(s):  
Ashley Prichard ◽  
Raveena Chhibber ◽  
Jon King ◽  
Kate Athanassiades ◽  
Mark Spivak ◽  
...  
Keyword(s):  
Piriform Cortex ◽  
Brain Regions ◽  
Neural Representation ◽  
Neural Activation ◽  
Sensory Stimuli ◽  
High Performing ◽  
Odor Processing ◽  
Fmri Study ◽  
Dog Brain ◽  
Odor Mixtures

Abstract In working and practical contexts, dogs rely upon their ability to discriminate a target odor from distracting odors and other sensory stimuli. Using awake functional magnetic resonance imaging (fMRI) in 18 dogs, we examined the neural mechanisms underlying odor discrimination between 2 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 clarify the neural representation of odor mixtures in the dog brain, we used a random forest classifier to compare multilabel (elemental) versus 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’ 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.

Odor Specificity of Habituation in the Rat Anterior Piriform Cortex

2000 ◽  
Vol 83 (1) ◽  
pp. 139-145 ◽  
Author(s):  
Donald A. Wilson
Keyword(s):  
Cortical Plasticity ◽  
Piriform Cortex ◽  
Afferent Input ◽  
Straight Chain ◽  
Anterior Piriform Cortex ◽  
Odor Processing ◽  
Before And After ◽  
Odor Mixtures ◽  
Evoked Activity ◽  
High Degree

Exposure to odorants results in a rapid (<10 s) reduction in odor-evoked activity in the rat piriform cortex despite relatively maintained afferent input from olfactory bulb mitral cells. To further understand this form of cortical plasticity, a detailed analysis of its odor specificity was performed. Habituation of odor responses in anterior piriform cortex single units was examined in anesthetized, freely breathing rats. The magnitude of single-unit responses of layer II/III neurons to 2-s odor pulses were examined before and after a 50-s habituating stimulus of either the same or different odor. The results demonstrated that odor habituation was odor specific, with no significant cross-habituation between either markedly different single odors or between odors within a series of straight chain alkanes. Furthermore, habituation to binary 1:1 mixtures produced minimal cross-habituation to the components of that mixture. These latter results may suggest synthetic odor processing in the olfactory system, with novel odor mixtures processed as unique stimuli. Potential mechanisms of odor habituation in the piriform cortex must be able to account for the high degree of specificity of this effect.

scholarly journals The distributed circuit within the piriform cortex makes odor discrimination robust

2018 ◽  
Vol 526 (17) ◽  
pp. 2725-2743 ◽  
Author(s):  
Shyam Srinivasan ◽  
Charles F. Stevens
Keyword(s):  
Piriform Cortex ◽  
Odor Discrimination

scholarly journals Statistical assessment of the stability of neural movement representations

2011 ◽  
Vol 106 (2) ◽  
pp. 764-774 ◽  
Author(s):  
Ian H. Stevenson ◽  
Anil Cherian ◽  
Brian M. London ◽  
Nicholas A. Sachs ◽  
Eric Lindberg ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Tuning Curve ◽  
Modulation Depth ◽  
Measurement Noise ◽  
Neural Representation ◽  
Experimental Conditions ◽  
Sensory Stimuli ◽  
Tuning Curves ◽  
Dynamic Tuning ◽  
Preferred Direction

In systems neuroscience, neural activity that represents movements or sensory stimuli is often characterized by spatial tuning curves that may change in response to training, attention, altered mechanics, or the passage of time. A vital step in determining whether tuning curves change is accounting for estimation uncertainty due to measurement noise. In this study, we address the issue of tuning curve stability using methods that take uncertainty directly into account. We analyze data recorded from neurons in primary motor cortex using chronically implanted, multielectrode arrays in four monkeys performing center-out reaching. With the use of simulations, we demonstrate that under typical experimental conditions, the effect of neuronal noise on estimated preferred direction can be quite large and is affected by both the amount of data and the modulation depth of the neurons. In experimental data, we find that after taking uncertainty into account using bootstrapping techniques, the majority of neurons appears to be very stable on a timescale of minutes to hours. Lastly, we introduce adaptive filtering methods to explicitly model dynamic tuning curves. In contrast to several previous findings suggesting that tuning curves may be in constant flux, we conclude that the neural representation of limb movement is, on average, quite stable and that impressions to the contrary may be largely the result of measurement noise.

Hedonic-Specific Activity in Piriform Cortex During Odor Imagery Mimics That During Odor Perception

2007 ◽  
Vol 98 (6) ◽  
pp. 3254-3262 ◽  
Author(s):  
Moustafa Bensafi ◽  
Noam Sobel ◽  
Rehan M. Khan
Keyword(s):  
Specific Activity ◽  
Piriform Cortex ◽  
Brain Regions ◽  
Specific Pattern ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Odor Perception ◽  
Cortical Areas ◽  
Visual Cortical ◽  
Left Insula

Although it is known that visual imagery is accompanied by activity in visual cortical areas, including primary visual cortex, whether olfactory imagery exists remains controversial. Here we asked whether cue-dependent olfactory imagery was similarly accompanied by activity in olfactory cortex, and in particular whether hedonic-specific patterns of activity evident in olfactory perception would also be present during olfactory imagery. We used functional magnetic resonance imaging to measure activity in subjects who alternated between smelling and imagining pleasant and unpleasant odors. Activity induced by imagining odors mimicked that induced by perceiving real odorants, not only in the particular brain regions activated, but also in its hedonic-specific pattern. For both real and imagined odors, unpleasant stimuli induced greater activity than pleasant stimuli in the left frontal portion of piriform cortex and left insula. These findings combine with findings from other modalities to suggest activation of primary sensory cortical structures during mental imagery of sensory events.

Distinct Effects of D9-tetrahydrocannabinol and Cannabidiol on Neural Activation During Emotional Processing

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1 ◽  
Author(s):  
P. Fusar-Poli
Keyword(s):  
Emotional Processing ◽  
Electrodermal Activity ◽  
Brain Regions ◽  
Posterior Cingulate Cortex ◽  
Psychotic Symptoms ◽  
Neural Activation ◽  
Double Blind ◽  
Posterior Cingulate ◽  
Fearful Faces ◽  
Scanning Session

Aims:Cannabis use can both increase and reduce anxiety in humans. The neurophysiological substrates of these effects are unknown.Method:Fifteen healthy English-native right-handed men were studied on three separate occasions using an event-related fMRI paradigm while viewing faces that implicitly elicited different levels of anxiety. Each scanning session was preceded by the ingestion of either 10mg of D-9-THC, 600mg of CBD, or a placebo, in a double-blind, randomised, placebo controlled design. Electrodermal activity (Skin Conductance Response, SCR) and objective and subjective ratings of anxiety were recorded durign the scanning.Results:D-9THC increased anxiety, as well as levels of intoxication, sedation and psychotic symptoms, whereas there was a trend for a reduction in anxiety following administration of CBD. The number of SCR fluctuations during the processing of intensely fearful faces increased following administration of D-9THC but decreased following administration of CBD. CBD attenuated the BOLD signal in the amygdala and the anterior and posterior cingulate cortex while subjects were processing intensely fearful faces, and its suppression of the amygdalar and posterior cingulate responses was correlated with the concurrent reduction in SCR fluctuations. D-9-THC mainly modulated activation in frontal and parietal areas.Conclusions:D-9-THC and CBD had clearly distinct effects on the neural, eclectrodermal and symptomatic response to fearful faces. The effects of CBD on activation in limbic and paralimbic regions may contribute to its ability to reduce autonomic arousal and subjective anxiety, whereas the anxiogenic effects of D-9-THC may be related to effects in other brain regions.

scholarly journals SAT-606 Distribution of Beta Klotho Gene Expression in the Mouse Brain

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Bianca S Bono ◽  
Persephone A Miller ◽  
Nikita K Koziel Ly ◽  
Melissa J Chee
Keyword(s):  
Basolateral Amygdala ◽  
Piriform Cortex ◽  
Brain Regions ◽  
Brain Atlas ◽  
Hypothalamic Nucleus ◽  
Fibroblast Growth Factor 21 ◽  
Lateral Olfactory Tract ◽  
Hypothalamic Area ◽  
Low Levels ◽  
The Brain

Abstract Fibroblast growth factor 21 (FGF21) has emerged as a critical endocrine factor for understanding the neurobiology of obesity, such as by the regulation thermogenesis, food preference, and metabolism, as well as for neuroprotection in Alzheimer’s disease and traumatic brain injury. FGF21 is synthesized primarily by the liver and pancreas then crosses the blood brain barrier to exert its effects in the brain. However, the sites of FGF21 action in the brain is not well-defined. FGF21 action requires the activation of FGF receptor 1c as well as its obligate co-receptor beta klotho (KLB). In order to determine the sites of FGF21 action, we mapped the distribution of Klb mRNA by in situ hybridization using RNAscope technology. We labeled Klb distribution throughout the rostrocaudal axis of male wildtype mice by amplifying Klb hybridization using tyramine signal amplification and visualizing Klb hybridization using Cyanine 3 fluorescence. The resulting Klb signal appears as punctate red “dots,” and each Klb neuron may express low (1–4 dots), medium (5–9 dots), or high levels (10+ dots) of Klb hybridization. We then mapped individual Klb expressing neuron to the atlas plates provided by the Allen Brain Atlas in order to determine Klb distribution within the substructures of each brain region, which are defined by Nissl-based parcellations of cytoarchitectural boundaries. The distribution of Klb mRNA is widespread throughout the brain, and the brain regions analyzed thus far point to notable expression in the hypothalamus, amygdala, hippocampus, and the cerebral cortex. The highest expression of Klb was localized to the suprachiasmatic nucleus in the hypothalamus, which contained low and medium Klb-expressing neurons in the lateral hypothalamic area and ventromedial hypothalamic nucleus while low expressing Klb neurons were seen in the paraventricular and dorsmedial hypothalamic nucleus. Hippocampal Klb expression was limited to the dorsal region and largely restricted to the pyramidal cell layer of the dentate gyrus, CA3, CA2, and CA1 but at low levels only. In the amygdala, low and medium Klb expressing cells were seen in lateral amygdala nucleus while low levels were observed in the basolateral amygdala nucleus. Cortical Klb expression analyzed thus far included low Klb-expressing neurons in the olfactory areas, including layers 2 and 3 of piriform cortex and nucleus of the lateral olfactory tract. These findings are consistent with the known roles of FGF21 in the central regulation of energy balance, but also implicates potentially wide-ranging effects of FGF21 such as in executive functions.

scholarly journals Decoding the Information Structure Underlying the Neural Representation of Concepts

2021 ◽  
Author(s):  
Leonardo Fernandino ◽  
Lisa L. Conant ◽  
Colin J. Humphries ◽  
Jeffrey R. Binder
Keyword(s):  
Information Structure ◽  
Conceptual Knowledge ◽  
Neural Representation ◽  
Neural Activation ◽  
Activation Patterns ◽  
Concept Representation ◽  
Native Space ◽  
Distributional Information ◽  
Similarity Structure ◽  
Types Of Information

The nature of the neural code underlying conceptual knowledge remains a major unsolved problem in cognitive neuroscience. Three main types of information have been proposed as candidates for the neural representations of lexical concepts: taxonomic (i.e., information about category membership and inter-category relations), distributional (i.e., information about patterns of word co-occurrence in natural language use), and experiential (i.e., information about sensory-motor, affective, and other features of phenomenal experience engaged during concept acquisition). In two experiments, we investigated the extent to which these three types of information are encoded in the neural activation patterns associated with hundreds of English nouns from a wide variety of conceptual categories. Participants made familiarity judgments on the meaning of written nouns while undergoing functional MRI. A high-resolution, whole-brain activation map was generated for each noun in each participant′s native space. These word-specific activation maps were used to evaluate different representational spaces corresponding to the three types of information described above. In both studies, we found a striking advantage for experience-based models in most brain areas previously associated with concept representation. Partial correlation analyses revealed that only experiential information successfully predicted concept similarity structure when inter-model correlations were taken into account. This pattern of results was found independently for object concepts and event concepts. Our findings indicate that the neural representation of conceptual knowledge primarily encodes information about features of experience, and that - to the extent that it is represented in the brain - taxonomic and distributional information may rely on such an experience-based code.

scholarly journals The dominant functional nicotinic receptor in progenitor cells in the rostral migratory stream is the α3β4 subtype

2013 ◽  
Vol 109 (3) ◽  
pp. 867-872 ◽  
Author(s):  
Geeta Sharma
Keyword(s):  
Olfactory Bulb ◽  
Perceptual Learning ◽  
Progenitor Cells ◽  
Glutamate Release ◽  
Brain Regions ◽  
Odor Discrimination ◽  
Rostral Migratory Stream ◽  
Receptor Expression ◽  
Granule Cell Layer ◽  
Migratory Stream

Addition of newly generated neurons into mature neural circuits in the adult CNS responds to changes in neurotransmitter levels and is tightly coupled to the activity of specific brain regions. This postnatal neurogenesis contributes to plasticity of the olfactory bulb and hippocampus and is thought to play a role in learning and memory, context and odor discrimination, as well as perceptual learning. While acetylcholine plays an important role in odor discrimination and perceptual learning, its role in adult neurogenesis in the olfactory bulb has not been elucidated. In this study, I have examined the functional expression of nAChRs in progenitor cells of the rostral migratory stream (RMS) in the adult olfactory bulb of mice. I show that most of these cells in the RMS exhibit large nAChR-mediated calcium transients upon application of acetylcholine (ACh). Unlike in the hippocampus, the predominant functional nAChRs on progenitor cells are of α3β4 subtype. Interestingly, functional receptor expression is lost once progenitor cells mature, and are incorporated into the granule cell layer. Instead, nAChRs are now expressed on some presynaptic terminals and modulate glutamate release onto granule cells. My results imply that ACh is a part of the permissive niche and likely plays a role in development of progenitor cells.

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