Organization of the Macaque Extrastriate Visual Cortex Re-Examined Using the Principle of Spatial Continuity of Function

How is the macaque monkey extrastriate cortex organized? Is vision divisible into separate tasks, such as object recognition and spatial processing, each emphasized in a different anatomical stream? If so, how many streams exist? What are the hierarchical relationships among areas? The present study approached the organization of the extrastriate cortex in a novel manner. A principled relationship exists between cortical function and cortical topography. Similar functions tend to be located near each other, within the constraints of mapping a highly dimensional space of functions onto the two-dimensional space of the cortex. We used this principle to re-examine the functional organization of the extrastriate cortex given current knowledge about its topographic organization. The goal of the study was to obtain a model of the functional relationships among the visual areas, including the number of functional streams into which they are grouped, the pattern of informational overlap among the streams, and the hierarchical relationships among areas. To test each functional description, we mapped it to a model cortex according to the principle of optimal continuity and assessed whether it accurately reconstructed a version of the extrastriate topography. Of the models tested, the one that best reconstructed the topography included four functional streams rather than two, six levels of hierarchy per stream, and a specific pattern of informational overlap among streams and areas. A specific mixture of functions was predicted for each visual area. This description matched findings in the physiological literature, and provided predictions of functional relationships that have yet to be tested physiologically.

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ABA Metabolism and Homeostasis in Seed Dormancy and Germination

International Journal of Molecular Sciences ◽

10.3390/ijms22105069 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5069

Author(s):

Naoto Sano ◽

Annie Marion-Poll

Keyword(s):

Seed Dormancy ◽

Current Knowledge ◽

Fine Tuning ◽

Environmental Signals ◽

Hormone Synthesis ◽

Control Seed ◽

Functional Relationships ◽

Aba Metabolism ◽

Natural Variations ◽

Germinating Seeds

Abscisic acid (ABA) is a key hormone that promotes dormancy during seed development on the mother plant and after seed dispersal participates in the control of dormancy release and germination in response to environmental signals. The modulation of ABA endogenous levels is largely achieved by fine-tuning, in the different seed tissues, hormone synthesis by cleavage of carotenoid precursors and inactivation by 8′-hydroxylation. In this review, we provide an overview of the current knowledge on ABA metabolism in developing and germinating seeds; notably, how environmental signals such as light, temperature and nitrate control seed dormancy through the adjustment of hormone levels. A number of regulatory factors have been recently identified which functional relationships with major transcription factors, such as ABA INSENSITIVE3 (ABI3), ABI4 and ABI5, have an essential role in the control of seed ABA levels. The increasing importance of epigenetic mechanisms in the regulation of ABA metabolism gene expression is also described. In the last section, we give an overview of natural variations of ABA metabolism genes and their effects on seed germination, which could be useful both in future studies to better understand the regulation of ABA metabolism and to identify candidates as breeding materials for improving germination properties.

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Functional organization of human posterior parietal cortex: grasping- and reaching-related activations relative to topographically organized cortex

Journal of Neurophysiology ◽

10.1152/jn.00657.2012 ◽

2013 ◽

Vol 109 (12) ◽

pp. 2897-2908 ◽

Cited By ~ 74

Author(s):

Christina S. Konen ◽

Ryan E. B. Mruczek ◽

Jessica L. Montoya ◽

Sabine Kastner

Keyword(s):

Neural Networks ◽

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Functional Organization ◽

Macaque Monkey ◽

Superior Parietal Lobule ◽

Movement Type ◽

The Neural Networks ◽

Posterior Parietal ◽

The Relationship

The act of reaching to grasp an object requires the coordination between transporting the arm and shaping the hand. Neurophysiological, neuroimaging, neuroanatomic, and neuropsychological studies in macaque monkeys and humans suggest that the neural networks underlying grasping and reaching acts are at least partially separable within the posterior parietal cortex (PPC). To better understand how these neural networks have evolved in primates, we characterized the relationship between grasping- and reaching-related responses and topographically organized areas of the human intraparietal sulcus (IPS) using functional MRI. Grasping-specific activation was localized to the left anterior IPS, partially overlapping with the most anterior topographic regions and extending into the postcentral sulcus. Reaching-specific activation was localized to the left precuneus and superior parietal lobule, partially overlapping with the medial aspects of the more posterior topographic regions. Although the majority of activity within the topographic regions of the IPS was nonspecific with respect to movement type, we found evidence for a functional gradient of specificity for reaching and grasping movements spanning posterior-medial to anterior-lateral PPC. In contrast to the macaque monkey, grasp- and reach-specific activations were largely located outside of the human IPS.

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Functional organization of color domains in V1 and V2 of Macaque monkey revealed by optical imaging

Journal of Vision ◽

10.1167/6.6.405 ◽

2010 ◽

Vol 6 (6) ◽

pp. 405-405 ◽

Cited By ~ 3

Author(s):

A. W. Roe ◽

H. D. Lu

Keyword(s):

Optical Imaging ◽

Functional Organization ◽

Macaque Monkey

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Unique Features of Subcortical Circuits in a Macaque Model of Congenital Blindness

Cerebral Cortex ◽

10.1093/cercor/bhz175 ◽

2019 ◽

Vol 30 (3) ◽

pp. 1407-1421 ◽

Cited By ~ 1

Author(s):

Loïc Magrou ◽

Pascal Barone ◽

Nikola T Markov ◽

Gwylan Scheeren ◽

Herbert P Killackey ◽

...

Keyword(s):

Visual System ◽

Functional Organization ◽

Extrastriate Cortex ◽

Drastic Reduction ◽

Congenital Blindness ◽

Macaque Model ◽

Cortical Projections ◽

Visual Areas ◽

Functional Consequences ◽

The Brain

Abstract There is an extensive modification of the functional organization of the brain in the congenital blind human, although there is little understanding of the structural underpinnings of these changes. The visual system of macaque has been extensively characterized both anatomically and functionally. We have taken advantage of this to examine the influence of congenital blindness in a macaque model of developmental anophthalmia. Developmental anophthalmia in macaque effectively removes the normal influence of the thalamus on cortical development leading to an induced “hybrid cortex (HC)” combining features of primary visual and extrastriate cortex. Here we show that retrograde tracers injected in early visual areas, including HC, reveal a drastic reduction of cortical projections of the reduced lateral geniculate nucleus. In addition, there is an important expansion of projections from the pulvinar complex to the HC, compared to the controls. These findings show that the functional consequences of congenital blindness need to be considered in terms of both modifications of the interareal cortical network and the ascending visual pathways.

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Functional discrimination of sea anemone neurotoxins using 3D-plotting

Open Life Sciences ◽

10.2478/s11535-008-0064-z ◽

2009 ◽

Vol 4 (1) ◽

pp. 41-49

Author(s):

Ludis Morales ◽

Orlando Acevedo ◽

María Martínez ◽

Dmitry Gokhman ◽

Carlos Corredor

Keyword(s):

Amino Acid ◽

Dimensional Space ◽

Three Dimensional ◽

Sea Anemone ◽

Amino Acid Sequences ◽

Peptide Sequence ◽

Sea Anemones ◽

Functional Relationships ◽

Voltage Dependent ◽

Three Dimensional Space

AbstractOne of the most important goals in structural biology is the identification of functional relationships among the structure of proteins and peptides. The purpose of this study was to (1) generate a model based on theoretical and computational considerations among amino acid sequences within select neurotoxin peptides, and (2) compare the relationship these values have to the various toxins tested. We employed isolated neurotoxins from sea anemones with established specific potential to act on voltage-dependent sodium and potassium channel activity as our model. Values were assigned to each amino acid in the peptide sequence of the neurotoxins tested using the Number of Lareo and Acevedo algorithm (NULA). Once the NULA number was obtained, it was then plotted using three dimensional space coordinates. The results of this study allow us to report, for the first time, that there is a different numerical and functional relationship between the sequences of amino acids from sea anemone neurotoxins, and the resulting numerical relationship for each peptide, or NULA number, has a unique location in three-dimensional space.

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Proprioception From a Spinocerebellar Perspective

Physiological Reviews ◽

10.1152/physrev.2001.81.2.539 ◽

2001 ◽

Vol 81 (2) ◽

pp. 539-568 ◽

Cited By ~ 160

Author(s):

G. Bosco ◽

R. E. Poppele

Keyword(s):

Spinal Cord ◽

Nervous System ◽

Functional Organization ◽

Body Position ◽

Historical Context ◽

Sensory Information ◽

Functional Relationships ◽

Central Neurons ◽

Global Representation ◽

Limb Kinematics

This review explores how proprioceptive sensory information is organized at spinal cord levels as it relates to a sense of body position and movement. The topic is considered in an historical context and develops a different framework that may be more in tune with current views of sensorimotor processing in other central nervous system structures. The dorsal spinocerebellar tract (DSCT) system is considered in detail as a model system that may be considered as an end point for the processing of proprioceptive sensory information in the spinal cord. An analysis of this system examines sensory processing at the lowest levels of synaptic connectivity with central neurons in the nervous system. The analysis leads to a framework for proprioception that involves a highly flexible network organization based in some way on whole limb kinematics. The functional organization underlying this framework originates with the biomechanical linkages in the limb that establish functional relationships among the limb segments. Afferent information from limb receptors is processed further through a distributed neural network in the spinal cord. The result is a global representation of hindlimb parameters rather than a muscle-by-muscle or joint-by-joint representation.

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Functional organization of inferior area 6 in the macaque monkey

Experimental Brain Research ◽

10.1007/bf00248741 ◽

1988 ◽

Vol 71 (3) ◽

pp. 475-490 ◽

Cited By ~ 317

Author(s):

M. Gentilucci ◽

L. Fogassi ◽

G. Luppino ◽

M. Matelli ◽

R. Camarda ◽

...

Keyword(s):

Functional Organization ◽

Macaque Monkey ◽

Area 6

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rest2vec: Vectorizing the resting-state functional connectome using graph embedding

10.1101/2020.05.10.085332 ◽

2020 ◽

Author(s):

Zachery D. Morrissey ◽

Liang Zhan ◽

Olusola Ajilore ◽

Alex D. Leow

Keyword(s):

Language Processing ◽

Resting State ◽

Functional Organization ◽

Binary Classification ◽

Full Range ◽

Graph Embedding ◽

Brain Regions ◽

Intrinsic Geometry ◽

Functional Relationships ◽

Functional Connectome

AbstractResting-state functional magnetic resonance imaging (rs-fmri) is widely used in connectomics for studying the functional relationships between regions of the human brain. rs-fmri connectomics, however, has inherent analytical challenges, such as accounting for negative correlations. In addition, functional relationships between brain regions do not necessarily correspond to their anatomical distance, making the intrinsic geometry of the functional connectome less well understood. Recent techniques in natural language processing and machine learning, such as word2vec, have used embedding methods to map high-dimensional data into meaningful vector spaces. Inspired by this approach, we have developed a graph embedding pipeline, rest2vec, for studying the intrinsic geometry of functional connectomes. We demonstrate how rest2vec uses the phase angle spatial embedding (phase) method with dimensionality reduction techniques to embed the functional connectome into lower dimensions. Rest2vec can also be linked to the maximum mean discrepancy (mmd) metric to assign functional modules of the connectome in a continuous manner, improving upon traditional binary classification methods. Together, this allows for studying the functional connectome such that the full range of correlative information is preserved and gives a more informed understanding of the functional organization of the brain.

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