Biology subjects

Liu, A. G.

Publications and source records attributed to Liu, A. G..

3 recordsLinked to original sources

bioRxiv2020

Tasting Pictures: Viewing Images of Foods Evokes Taste-Quality-Specific Activity in Gustatory Insular Cortex

Previous studies have shown that the conceptual representation of food involves brain regions associated with taste perception. The specificity of this response, however, is unknown. Does viewing pictures of food produce a general, non-specific response in taste-sensitive regions of the brain? Or, is the response specific for how a particular food tastes? Building on recent findings that specific tastes can be decoded from taste-sensitive regions of insular cortex, we asked whether viewing pictures of foods associated with a specific taste (e.g., sweet, salty, sour) can also be decoded from these same regions and if so, are the patterns of neural activity elicited by the pictures and their associated tastes similar? Using ultra-high resolution functional magnetic resonance imaging at high magnetic field strength (7-Tesla), we were able to decode specific tastes delivered during scanning, as well as the specific taste category associated with food pictures within the dorsal mid-insula, a primary taste responsive region of brain. Thus, merely viewing food pictures triggers an automatic retrieval of specific taste quality information associated with the depicted foods, within gustatory cortex. However, the patterns of activity elicited by pictures and their associated tastes were unrelated, thus suggesting a clear neural distinction between inferred and directly experienced sensory events. These data show how higher-order inferences derived from stimuli in one modality (i.e. vision) can be represented in brain regions typically thought to represent only low-level information about a different modality (i.e. taste). Significance StatementDoes a picture of an apple taste sweet? Previous studies have shown that viewing food pictures activates brain regions involved in taste perception. However, its unclear if this response is actually specific to the taste of depicted foods. Using ultra-high resolution functional magnetic resonance imaging and multi-voxel pattern analysis, we decoded specific tastes delivered during scanning, as well as the dominant tastes associated with food pictures within primary taste cortex. Thus, merely viewing pictures of food evokes an automatic retrieval of information about the taste of those foods. These results show how higher-order information from one sensory modality (i.e. vision) can be represented in brain regions thought to represent only low-level information from a different modality (i.e. taste).

neuroscience↗

bioRxiv2019

The influence of environmental setting on the community ecology of Ediacaran organisms

The broad-scale environment plays a substantial role in shaping modern marine ecosystems, but the degree to which palaeocommunities were influenced by their environment is unclear. To investigate how broad-scale environment influenced the community ecology of early animal ecosystems we employed spatial point process analyses to examine the community structure of seven bedding-plane assemblages of late Ediacaran age (558–550 Ma), drawn from a range of environmental settings and global localities. The studied palaeocommunities exhibit marked differences in the response of their component taxa to sub-metre-scale habitat heterogeneities on the seafloor. Shallow-marine palaeocommunities were heavily influenced by local habitat heterogeneities, in contrast to their deep-water counterparts. Lower species richness in deep-water Ediacaran assemblages compared to shallow-water counterparts across the studied time-interval could have been driven by this environmental patchiness, because habitat heterogeneities correspond to higher diversity in modern marine environments. The presence of grazers and detritivores within shallow-water communities may have promoted local patchiness, potentially initiating a chain of increasing heterogeneity of benthic communities from shallow to deep-marine depositional environments. Our results provide quantitative support for the “Savannah” hypothesis for early animal diversification – whereby Ediacaran diversification was driven by patchiness in the local benthic environment.Author Contributions E. Mitchell conceived this paper and wrote the first draft. N. Bobkov, A. Kolesnikov, N. Sozonov and D. Grazhdankin collected the data for DS surface. N. Bobkov and N. Sozonov performed the analyses on DS surface. N. Bykova, S. Xiao, and D. Grazhdankin collected the data for WS, KH1 and KH2 surfaces and E. Mitchell performed the analyses. A. Dhungana and A. Liu collected the data for FUN4 and FUN5 surfaces and A. Dhungana performed the analyses. T. Mustill and D. Grazhdankin collected the data for KS and T. Mustill and E. Mitchell performed the analyses. I. Hogarth developed the software for preliminary KS surface analyses. E. Mitchell, N. Bobkov, N. Bykova, A. Dhungana, A. Kolesnikov, A. Liu, S. Xiao and D. Grazhdankin discussed the results and prepared the manuscript.View Full Text

paleontology↗

bioRxiv2019

Taste quality representation in the human brain

In the mammalian brain, the insula is the primary cortical substrate involved in the perception of taste. Recent imaging studies in rodents have identified a gustotopic organization in the insula, whereby distinct insula regions are selectively responsive to one of the five basic tastes. However, numerous studies in monkeys have reported that gustatory cortical neurons are broadly-tuned to multiple tastes, and tastes are not represented in discrete spatial locations. Neuroimaging studies in humans have thus far been unable to discern between these two models, though this may be due to the relatively low spatial resolution employed in taste studies to date. In the present study, we examined the spatial representation of taste within the human brain using ultra-high resolution functional magnetic resonance imaging (MRI) at high magnetic field strength (7-Tesla). During scanning, participants tasted sweet, salty, sour and tasteless liquids, delivered via a custom-built MRI-compatible tastant-delivery system. Our univariate analyses revealed that all tastes (vs. tasteless) activated primary taste cortex within the bilateral dorsal mid-insula, but no brain region exhibited a consistent preference for any individual taste. However, our multivariate searchlight analyses were able to reliably decode the identity of distinct tastes within those mid-insula regions, as well as brain regions involved in affect and reward, such as the striatum, orbitofrontal cortex, and amygdala. These results suggest that taste quality is not represented topographically, but by a combinatorial spatial code, both within primary taste cortex as well as regions involved in processing the hedonic and aversive properties of taste.

neuroscience↗