An Interactive Annotated World Bibliography of Printed and Digital Works in the History of Medicine and the Life Sciences from Circa 2000 BCE to 2022 by Fielding H. Garrison (1870-1935), Leslie T. Morton (1907-2004), and Jeremy M. Norman (1945- ) Traditionally Known as “Garrison-Morton”

16011 entries, 14068 authors and 1941 subjects. Updated: June 19, 2024

SPORNS, Olaf

3 entries
  • 12736

Architecture of the cerebral cortical association connectome underlying cognition.

Proc. Nat. Acad. Sci. (USA), 112, E2093-E2101, 2015.

"Significance

"Connections between cerebral cortex regions are known as association connections, and neural activity in the network formed by these connections is thought to generate cognition. Network analysis of microscopic association connection data produced over the last 40 years in a small, easily studied mammal suggests a new way to describe the organization of the cortical association network. Basically, it consists of four modules with an anatomical shell–core arrangement and asymmetric connections within and between modules, implying at least partly “hardwired,” genetically determined biases of information flow through the cortical association network. The results advance the goal of achieving a global nervous system wiring diagram of connections and provide another step toward understanding the cellular architecture and mechanisms underpinning cognition.

"Abstract

"Cognition presumably emerges from neural activity in the network of association connections between cortical regions that is modulated by inputs from sensory and state systems and directs voluntary behavior by outputs to the motor system. To reveal global architectural features of the cortical association connectome, network analysis was performed on >16,000 reports of histologically defined axonal connections between cortical regions in rat. The network analysis reveals an organization into four asymmetrically interconnected modules involving the entire cortex in a topographic and topologic core–shell arrangement. There is also a topographically continuous U-shaped band of cortical areas that are highly connected with each other as well as with the rest of the cortex extending through all four modules, with the temporal pole of this band (entorhinal area) having the most cortical association connections of all. These results provide a starting point for compiling a mammalian nervous system connectome that could ultimately reveal novel correlations between genome-wide association studies and connectome-wide association studies, leading to new insights into the cellular architecture supporting cognition."

Available from pnas.org at this link.



Subjects: ANATOMY › Neuroanatomy › Cytoarchitecture, NEUROSCIENCE › Cognitive Neuroscience, NEUROSCIENCE › Computational Neuroscience, NEUROSCIENCE › Computational Neuroscience › Connectomics, PSYCHOLOGY › Cognition
  • 12737

Organizing principles for the cerebral cortex network of commissural and association connections.

Proc. Nat. Acad. Sci. (USA), 114, E9692-E9701, 2017.

"Significance

"The cerebral cortex supports cognition and is a structure common to all mammals. The major cortical subdivisions (its gray matter regions) are connected by a complex network of axonal connections that includes connections between regions in the same hemisphere (association connections on the right or left side) and those between hemispheres (commissural connections between opposite sides). A database of over 5,000 connections in the cortical network was extracted from the literature, and network analysis revealed three identical cortical modules (neural subsystems) on each side. One appears to deal especially with the external world, one with the viscera, and one with planning, prioritization, and self-awareness. A set of general organizing principles for association and commissural connections also emerged from the analysis.

"Abstract

"Cognition is supported by a network of axonal connections between gray matter regions within and between right and left cerebral cortex. Global organizing principles of this circuitry were examined with network analysis tools applied to monosynaptic association (within one side) and commissural (between sides) connections between all 77 cortical gray matter regions in each hemisphere of the rat brain. The analysis used 32,350 connection reports expertly collated from published pathway tracing experiments, and 5,394 connections of a possible 23,562 were identified, for a connection density of 23%—of which 20% (1,084) were commissural. Network community detection yielded a stable bihemispheric six-module solution, with an identical set in each hemisphere of three modules topographically forming a lateral core and medial shell arrangement of cortical regions. Functional correlations suggest the lateral module deals preferentially with environmental sensory-motor interactions and the ventromedial module deals preferentially with visceral control, affect, and short-term memory, whereas the dorsomedial module resembles the default mode network. Analysis of commissural connections revealed a set of unexpected rules to help generate hypotheses. Most notably, there is an order of magnitude more heterotopic than homotopic projections; all cortical regions send more association than commissural connections, and for each region, the latter are always a subset of the former; the number of association connections from each cortical region strongly correlates with the number of its commissural connections; and the module (dorsomedial) lying closest to the corpus callosum has the most complete set of commissural connections—and apparently the most complex function."

(Order of authorship in the original publication: Swanson, Hahn, Sporns).
Available from pnas.org at this link.



Subjects: ANATOMY › Neuroanatomy › Cytoarchitecture, COMPUTING/MATHEMATICS in Medicine & Biology, NEUROSCIENCE › Cognitive Neuroscience, NEUROSCIENCE › Computational Neuroscience, NEUROSCIENCE › Computational Neuroscience › Connectomics, PSYCHOLOGY › Cognition
  • 12738

Subsystem organization of axonal connections within and between right and left cerebral cortex and cerebral nuclei (endbrain).

Proc. Nat. Acad. Sci. (USA), 115, E6910-E6919, 2018.

"Significance

"The right and left cerebral hemispheres (together forming the endbrain) support cognition and affect, and, structurally, each hemisphere consists of a cortical sheet and set of deep nuclei (often called the basal ganglia). Experimental evidence in the literature identified more than 10,000 axonal macroconnections between the 244 gray matter regions of the endbrain, and the global organizing principles of the network formed by these connections were subjected to multiresolution consensus clustering analysis. The result was a hierarchy of subsystems that has only four components at the top level and 60 components at the bottom level. Furthermore, a region’s status as a connectivity hub in a network is not absolute; it depends on the size and coverage of its anatomical neighborhood.

"Abstract

"The endbrain (telencephalon) is at the rostral end of the central nervous system and is primarily responsible for supporting cognition and affect. Structurally, it consists of right and left cerebral hemispheres, each parceled into multiple cortical and nuclear gray matter regions. The global network organization of axonal macroconnections between the 244 regions forming the endbrain was analyzed with a multiresolution consensus clustering (MRCC) method that provides a hierarchical description of community clustering (modules or subsystems) within the network. Experimental evidence was collated from the neuroanatomical literature for the existence of 10,002 of a possible 59,292 connections within the network, and they cluster into four top-level subsystems and 60 bottom-level subsystems arranged in a 50-level hierarchy. Two top-level subsystems are bihemispheric: One deals with auditory and visual information, and the other corresponds broadly to the default mode network. The other two top-level subsystems are bilaterally symmetrical, and each deals broadly with somatic and visceral information. Because the entire endbrain connection matrix was assembled from multiple subconnectomes, it was easy to show that the status of a region as a connectivity hub is not absolute but, instead, depends on the size and coverage of its anatomical neighborhood. It was also shown numerically that creating an ultradense connection matrix by converting all “absent” connections to a “very weak” connection weight has virtually no effect on the clustering hierarchy. The next logical step in this project is to complete the forebrain connectome by adding the thalamus and hypothalamus (together, the interbrain) to the endbrain analysis."

(Order of authorship in the original publication: Swanson, Hahn Jeub, Fortunato, Sporns.)
Available from pnas.org at this link.



Subjects: ANATOMY › Neuroanatomy › Cytoarchitecture, COMPUTING/MATHEMATICS in Medicine & Biology, NEUROSCIENCE › Cognitive Neuroscience, NEUROSCIENCE › Computational Neuroscience, NEUROSCIENCE › Computational Neuroscience › Connectomics, PSYCHOLOGY › Cognition