Taste quality representation in the human brain

SUMMARYIn 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.

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Viewing images of foods evokes taste quality-specific activity in gustatory insular cortex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2010932118 ◽

2020 ◽

Vol 118 (2) ◽

pp. e2010932118

Author(s):

Jason A. Avery ◽

Alexander G. Liu ◽

John E. Ingeholm ◽

Stephen J. Gotts ◽

Alex Martin

Keyword(s):

Specific Activity ◽

Insular Cortex ◽

Brain Regions ◽

Taste Quality ◽

Taste Perception ◽

7 Tesla ◽

High Magnetic Field Strength ◽

Automatic Retrieval ◽

Level Information ◽

Food Pictures

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, nonspecific 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, and 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 ultrahigh-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).

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GABA—from Inhibition to Cognition: Emerging Concepts

The Neuroscientist ◽

10.1177/1073858417734530 ◽

2017 ◽

Vol 24 (5) ◽

pp. 501-515 ◽

Cited By ~ 18

Author(s):

T. Schmidt-Wilcke ◽

E. Fuchs ◽

K. Funke ◽

A. Vlachos ◽

F. Müller-Dahlhaus ◽

...

Keyword(s):

Cortical Neurons ◽

Brain Regions ◽

Mammalian Brain ◽

Resonance Spectroscopy ◽

Inhibitory Neurotransmitter ◽

Electrophysiological Properties ◽

Potential Strategy ◽

The One ◽

And Behavior

Neural functioning and plasticity can be studied on different levels of organization and complexity ranging from the molecular and synaptic level to neural circuitry of whole brain networks. Across neuroscience different methods are being applied to better understand the role of various neurotransmitter systems in the evolution of perception and cognition. GABA is the main inhibitory neurotransmitter in the adult mammalian brain and, depending on the brain region, up to 25% of the total number of cortical neurons are GABAergic interneurons. At the one end of the spectrum, GABAergic neurons have been accurately described with regard to cell morphological, molecular, and electrophysiological properties; at the other end researchers try to link GABA concentrations in specific brain regions to human behavior using magnetic resonance spectroscopy. One of the main challenges of modern neuroscience currently is to integrate knowledge from highly specialized subfields at distinct biological scales into a coherent picture that bridges the gap between molecules and behavior. In the current review, recent findings from different fields of GABA research are summarized delineating a potential strategy to develop a more holistic picture of the function and role of GABA.

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Temporal pattern recognition in the human brain: a dual simultaneous processing

10.1101/2021.10.21.465263 ◽

2021 ◽

Author(s):

Leonardo Bonetti ◽

Elvira Brattico ◽

Silvia EP Bruzzone ◽

Giulia Donati ◽

Gustavo Deco ◽

...

Keyword(s):

Pattern Recognition ◽

Human Brain ◽

Temporal Pattern ◽

Brain Regions ◽

Machine Learning Algorithms ◽

Brain Areas ◽

Simultaneous Processing ◽

Neural Information ◽

Complex Procedure ◽

Magnetic Resonance Imaging Mri

Pattern recognition is a major scientific topic. Strikingly, while machine learning algorithms are constantly refined, the human brain emerges as an ancestral biological example of such complex procedure. However, how it transforms sequences of single objects into meaningful temporal patterns remains elusive. Using magnetoencephalography (MEG) and magnetic resonance imaging (MRI), we discovered and mathematically modelled an inedited dual simultaneous processing responsible for pattern recognition in the brain. Indeed, while the objects of the temporal pattern were independently elaborated by a local, rapid brain processing, their combination into a meaningful superordinate pattern depended on a concurrent global, slower processing involving a widespread network of sequentially active brain areas. Expanding the established knowledge of neural information flow from low- to high-order brain areas, we revealed a novel brain mechanism based on simultaneous activity in different frequency bands within the same brain regions, highlighting its crucial role underlying complex cognitive functions.

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In vivo 3D Reconstruction of the Human Pallidothalamic and Nigrothalamic Pathways With Super-Resolution 7T MR Track Density Imaging and Fiber Tractography

Frontiers in Neuroanatomy ◽

10.3389/fnana.2021.739576 ◽

2021 ◽

Vol 15 ◽

Author(s):

Dae-Hyuk Kwon ◽

Sun Ha Paek ◽

Young-Bo Kim ◽

Haigun Lee ◽

Zang-Hee Cho

Keyword(s):

Basal Ganglia ◽

3D Reconstruction ◽

Human Brain ◽

Super Resolution ◽

Track Density ◽

7 Tesla ◽

Fiber Tractography ◽

Resolution Limit ◽

Magnetic Resonance Imaging Mri

The output network of the basal ganglia plays an important role in motor, associative, and limbic processing and is generally characterized by the pallidothalamic and nigrothalamic pathways. However, these connections in the human brain remain difficult to elucidate because of the resolution limit of current neuroimaging techniques. The present study aimed to investigate the mesoscopic nature of these connections between the thalamus, substantia nigra pars reticulata, and globus pallidus internal segment using 7 Tesla (7T) magnetic resonance imaging (MRI). In this study, track-density imaging (TDI) of the whole human brain was employed to overcome the limitations of observing the pallidothalamic and nigrothalamic tracts. Owing to the super-resolution of the TD images, the substructures of the SN, as well as the associated tracts, were identified. This study demonstrates that 7T MRI and MR tractography can be used to visualize anatomical details, as well as 3D reconstruction, of the output projections of the basal ganglia.

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Rapid purification and metabolomic profiling of synaptic vesicles from mammalian brain

10.1101/2020.06.05.136093 ◽

2020 ◽

Cited By ~ 1

Author(s):

Lynne Chantranupong ◽

Jessica L. Saulnier ◽

Wengang Wang ◽

Drew R. Jones ◽

Michael E. Pacold ◽

...

Keyword(s):

Cortical Neurons ◽

Synaptic Vesicles ◽

Brain Regions ◽

Mammalian Brain ◽

Metabolomic Profiling ◽

Polar Metabolites ◽

A Cell ◽

Cell Type Specific ◽

Rapid Purification ◽

Activity Dependent

AbstractNeurons communicate by the activity-dependent release of small-molecule neurotransmitters packaged into synaptic vesicles (SVs). Although many molecules have been identified as neurotransmitters, technical limitations have precluded a full metabolomic analysis of synaptic vesicle content. Here, we present a workflow to rapidly isolate SVs and to interrogate their metabolic contents at a high-resolution using mass spectrometry. We validated the enrichment of glutamate in SVs of primary cortical neurons using targeted polar metabolomics. Unbiased and extensive global profiling of SVs isolated from these neurons revealed that the only detectable polar metabolites they contain are the established neurotransmitters glutamate and GABA. Finally, we adapted the approach to enable quick capture of SVs directly from brain tissue and determined the neurotransmitter profiles of diverse brain regions in a cell-type specific manner. The speed, robustness, and precision of this method to interrogate SV contents will facilitate novel insights into the chemical basis of neurotransmission.

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Rapid purification and metabolomic profiling of synaptic vesicles from mammalian brain

eLife ◽

10.7554/elife.59699 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Lynne Chantranupong ◽

Jessica L Saulnier ◽

Wengang Wang ◽

Drew R Jones ◽

Michael E Pacold ◽

...

Keyword(s):

Cortical Neurons ◽

Synaptic Vesicles ◽

Brain Regions ◽

Mammalian Brain ◽

Metabolomic Profiling ◽

Polar Metabolites ◽

A Cell ◽

Cell Type Specific ◽

Rapid Purification ◽

Activity Dependent

Neurons communicate by the activity-dependent release of small-molecule neurotransmitters packaged into synaptic vesicles (SVs). Although many molecules have been identified as neurotransmitters, technical limitations have precluded a full metabolomic analysis of SV content. Here, we present a workflow to rapidly isolate SVs and to interrogate their metabolic contents at high-resolution using mass spectrometry. We validated the enrichment of glutamate in SVs of primary cortical neurons using targeted polar metabolomics. Unbiased and extensive global profiling of SVs isolated from these neurons revealed that the only detectable polar metabolites they contain are the established neurotransmitters glutamate and GABA. In addition, we adapted the approach to enable quick capture of SVs directly from brain tissue and determined the neurotransmitter profiles of diverse brain regions in a cell-type-specific manner. The speed, robustness, and precision of this method to interrogate SV contents will facilitate novel insights into the chemical basis of neurotransmission.

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Human brain regions responsive to visual motion stimuli: determination by magnetoencephalography and three dimensional MRI

Neuroscience Research ◽

10.1016/s0168-0102(00)81117-7 ◽

2000 ◽

Vol 38 ◽

pp. S45

Author(s):

M Bundo

Keyword(s):

Human Brain ◽

Visual Motion ◽

Three Dimensional ◽

Brain Regions

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An architectonic type principle in the development of laminar patterns of cortico-cortical connections

Brain Structure and Function ◽

10.1007/s00429-021-02219-6 ◽

2021 ◽

Author(s):

Sarah F. Beul ◽

Alexandros Goulas ◽

Claus C. Hilgetag

Keyword(s):

Structural Connectivity ◽

Macaque Monkey ◽

Brain Regions ◽

Adult Brain ◽

Mammalian Brain ◽

Cortical Connections ◽

Cortical Projections ◽

Structural Connections ◽

High Degree ◽

The Brain

AbstractStructural connections between cortical areas form an intricate network with a high degree of specificity. Many aspects of this complex network organization in the adult mammalian cortex are captured by an architectonic type principle, which relates structural connections to the architectonic differentiation of brain regions. In particular, the laminar patterns of projection origins are a prominent feature of structural connections that varies in a graded manner with the relative architectonic differentiation of connected areas in the adult brain. Here we show that the architectonic type principle is already apparent for the laminar origins of cortico-cortical projections in the immature cortex of the macaque monkey. We find that prenatal and neonatal laminar patterns correlate with cortical architectonic differentiation, and that the relation of laminar patterns to architectonic differences between connected areas is not substantially altered by the complete loss of visual input. Moreover, we find that the degree of change in laminar patterns that projections undergo during development varies in proportion to the relative architectonic differentiation of the connected areas. Hence, it appears that initial biases in laminar projection patterns become progressively strengthened by later developmental processes. These findings suggest that early neurogenetic processes during the formation of the brain are sufficient to establish the characteristic laminar projection patterns. This conclusion is in line with previously suggested mechanistic explanations underlying the emergence of the architectonic type principle and provides further constraints for exploring the fundamental factors that shape structural connectivity in the mammalian brain.

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Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

Nature Communications ◽

10.1038/s41467-021-25035-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Cody L. Call ◽

Dwight E. Bergles

Keyword(s):

Cortical Neurons ◽

Regional Differences ◽

Brain Regions ◽

Axon Diameter ◽

Neuronal Identity ◽

Cortical Areas ◽

Myelin Sheaths ◽

Parvalbumin Interneurons ◽

Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

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