Distinct representations of basic taste qualities in human gustatory cortex.
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ABSTRACT:
SUBMITTER: Chikazoe J
PROVIDER: S-EPMC6401093 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:A growing body of literature has demonstrated that primary sensory cortices are not exclusively unimodal, but can respond to stimuli of different sensory modalities. However, several questions concerning the neural representation of cross-modal stimuli remain open. Indeed, it is poorly understood if cross-modal stimuli evoke unique or overlapping representations in a primary sensory cortex and whether learning can modulate these representations. Here we recorded single unit responses to auditory, visual, somatosensory, and olfactory stimuli in the gustatory cortex (GC) of alert rats before and after associative learning. We found that, in untrained rats, the majority of GC neurons were modulated by a single modality. Upon learning, both prevalence of cross-modal responsive neurons and their breadth of tuning increased, leading to a greater overlap of representations. Altogether, our results show that the gustatory cortex represents cross-modal stimuli according to their sensory identity, and that learning changes the overlap of cross-modal representations.
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Project description:Novel taste memories, critical for animal survival, are consolidated to form long term memories which are dependent on translation regulation in the gustatory cortex We used microarray for identification of genes involved in novel taste learning at two time points- 1 and 3 hours following memory formation for novel taste Adult rats were separated into two groups- novel tatse (0.1% sacchain) and water, two time points were used 1, 3 hours following learnin. Rna was extracted and hybridized on Affymetrix microarray
2016-03-23 | E-GEOD-74546 | biostudies-arrayexpress
Project description:Novel taste memories, critical for animal survival, are consolidated to form long term memories which are dependent on translation regulation in the gustatory cortex We used microarray for identification of genes involved in novel taste learning at two time points- 1 and 3 hours following memory formation for novel taste
2016-03-23 | GSE74546 | GEO
Project description:Novel taste memories, critical for animal survival, are consolidated to form long term memories which are dependent on translation regulation in the gustatory cortex (GC) hours following acquisition. However, the role of transcription regulation in the process is unknown.Here, we report that transcription in the GC is necessary for taste learning in rats, and that drinking and its consequences, as well as the novel taste experience, affect transcription in the GC during taste memory consolidation. We show differential effects of learning on temporal dynamics in set of genes in the GC, including Arc/Arg3.1, known to regulate the homeostasis of excitatory synapses.We demonstrate that in taste learning, transcription programs were activated following the physiological responses (i.e., fluid consumption following a water restriction regime, reward, arousal of the animal, etc.) and the specific information about a given taste (i.e., taste novelty). Moreover, the cortical differential prolonged kinetics of mRNA following novel versus familiar taste learning may represent additional novelty related molecular response, where not only the total amount, but also the temporal dynamics of transcription is modulated by sensory experience of novel information.
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Project description:BackgroundRight insular cortex is involved in taste discrimination, but its functional organization is still poorly known. In general, sensory cortices represent the spatial prevalence of relevant features for each sensory modality (visual, auditory, somatosensory) in an ordered way across the cortical space. Following this analogy, we hypothesized that primary taste cortex is organized in similar ordered way in response to six tastes with known receptorial mechanisms (sweet, bitter, sour, salt, umami, CO2).DesignTen normal subjects were enrolled in a pilot study. We used functional magnetic resonance imaging (fMRI), a high resolution cortical registration method, and specialized procedures of feature prevalence localization, to map fMRI responses within the right insular cortex, to water solutions of quinine hydrochloride (bitter), Acesulfamate K (sweet), sodium chloride (salt), mono potassium glutamate + inosine 5' mono phosphate (Umami), citric acid (sour) and carbonated water (CO2). During an fMRI scan delivery of the solutions was applied in pseudo-random order interleaved with cleaning water.ResultsTwo subjects were discarded due to excessive head movements. In the remaining subjects, statistically significant activations were detected in the fMRI responses to all tastes in the right insular cortex (p<0.05, family-wise corrected for multiple comparisons). Cortical representation of taste prevalence highlighted two spatially segregated clusters, processing two and three tastes coupled together (sweet-bitter and salt-umami-sour), with CO2 in between.ConclusionsCortical representation of taste prevalence within the right primary taste cortex appears to follow the ecological purpose of enhancing the discrimination between safe nutrients and harmful substances.
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Project description:Research over the past decade has established the gustatory insular cortex (GC) as a model for studying how primary sensory cortices integrate sensory, affective, and cognitive signals. This integration occurs through time-varying patterns of neural activity. Selective silencing of GC activity during specific temporal windows provided evidence for GC's role in mediating taste palatability and expectation. Recent results also suggest that this area may play a role in decision making. However, existing data are limited to GC involvement in controlling the timing of stereotyped, orofacial reactions to aversive tastants during consumption. Here, we present electrophysiological, chemogenetic, and optogenetic results demonstrating the key role of GC in the execution of a taste-guided, reward-directed decision-making task. Mice were trained in a two-alternative choice task, in which they had to associate tastants sampled from a central spout with different actions (i.e., licking either a left or a right spout). Stimulus sampling and action were separated by a delay period. Electrophysiological recordings revealed chemosensory processing during the sampling period and the emergence of task-related, cognitive signals during the delay period. Chemogenetic silencing of GC impaired task performance. Optogenetic silencing of GC allowed us to tease apart the contribution of activity during sampling and delay periods. Although silencing during the sampling period had no effect, silencing during the delay period significantly impacted behavioral performance, demonstrating the importance of the cognitive signals processed by GC in driving decision making. Altogether, our data highlight a novel role of GC in controlling taste-guided, reward-directed choices and actions.
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Project description:We represent the locations of places (e.g., the coffee shop on 10th Street vs. the coffee shop on Peachtree Street) so that we can use them as landmarks to orient ourselves while navigating large-scale environments. While several neuroimaging studies have argued that the parahippocampal place area (PPA) represents such navigationally relevant information, evidence from other studies suggests otherwise, leaving this issue unresolved. Here we hypothesize that the PPA is, in fact, not well suited to recognize specific landmarks in the environment (e.g., the coffee shop on 10th Street), but rather is involved in recognizing the general category membership of places (e.g., a coffee shop, regardless of its location). Using fMRI multivoxel pattern analysis, we directly test this hypothesis. If the PPA represents landmark information, then it must be able to discriminate between 2 places of the same category, but in different locations. Instead, if the PPA represents general category information (as hypothesized here), then it will not represent the location of a particular place, but only the category of the place. As predicted, we found that the PPA represents 2 buildings from the same category, but in different locations, as more similar than 2 buildings from different categories, but in the same location. In contrast, another scene-selective region of cortex, the retrosplenial complex (RSC), showed the exact opposite pattern of results. Such a double dissociation suggests distinct neural systems involved in categorizing and navigating our environment, including the PPA and RSC, respectively.
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