Graded classes of cortical connections
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Graded classes of cortical connections : quantitative analyses of laminar projections to motion areas of cat extrastriate cortex. / Grant, Simon; Hilgetag, Claus C.
In: EUR J NEUROSCI, Vol. 22, No. 3, 08.2005, p. 681-96.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Graded classes of cortical connections
T2 - quantitative analyses of laminar projections to motion areas of cat extrastriate cortex
AU - Grant, Simon
AU - Hilgetag, Claus C
PY - 2005/8
Y1 - 2005/8
N2 - Current hierarchical models of the cerebral cortex are mainly based on qualitative connection studies. From wheatgerm-agglutinin-horseradish peroxidase injections, we examined the laminar patterns of projections to and between the three major subdivisions of the motion-processing lateral suprasylvian (LS) complex [areas posteromedial lateral suprasylvian area (PMLS), anteromedial lateral suprasylvian (AMLS), posterolateral lateral suprasylvian area (PLLS)] of cat extrastriate cortex and of an adjoining form-processing area, 21a. We counted approximately 145,000 labelled projection cells in 20 cortical areas in 11 cats, and applied various analyses to the data, expressed as the percent supragranular layer (%SG) origin of each connection. We report two main results. (i) A wide range of %SG values was obtained, both from each individual cat and across the 163 projections examined. Nonetheless, both hierarchical and non-parametric cluster analyses of the pooled connection origins suggested the presence of three distinct laminar projection classes, constrained by graded %SG values of 0-33%, 39-69% and 76-97%. These conformed, respectively, to feedback, lateral and feedforward laminar patterns seen qualitatively in our material. (ii) Hierarchical connectivity analyses suggested that PMLS, AMLS and PLLS are ordered in a hierarchical sequence. Macaque motion areas V5/MT, MST and FST are arranged in a similar sequence, and areas at equivalent levels of the two motion hierarchies have some analogous functional specializations. Our findings provide the first objective support for the three laminar projection classes that underpin existing theoretical models of hierarchical cortical organization, and they suggest that the implementation of higher-order motion processing evolved along similar lines in the cat and monkey visual cortex.
AB - Current hierarchical models of the cerebral cortex are mainly based on qualitative connection studies. From wheatgerm-agglutinin-horseradish peroxidase injections, we examined the laminar patterns of projections to and between the three major subdivisions of the motion-processing lateral suprasylvian (LS) complex [areas posteromedial lateral suprasylvian area (PMLS), anteromedial lateral suprasylvian (AMLS), posterolateral lateral suprasylvian area (PLLS)] of cat extrastriate cortex and of an adjoining form-processing area, 21a. We counted approximately 145,000 labelled projection cells in 20 cortical areas in 11 cats, and applied various analyses to the data, expressed as the percent supragranular layer (%SG) origin of each connection. We report two main results. (i) A wide range of %SG values was obtained, both from each individual cat and across the 163 projections examined. Nonetheless, both hierarchical and non-parametric cluster analyses of the pooled connection origins suggested the presence of three distinct laminar projection classes, constrained by graded %SG values of 0-33%, 39-69% and 76-97%. These conformed, respectively, to feedback, lateral and feedforward laminar patterns seen qualitatively in our material. (ii) Hierarchical connectivity analyses suggested that PMLS, AMLS and PLLS are ordered in a hierarchical sequence. Macaque motion areas V5/MT, MST and FST are arranged in a similar sequence, and areas at equivalent levels of the two motion hierarchies have some analogous functional specializations. Our findings provide the first objective support for the three laminar projection classes that underpin existing theoretical models of hierarchical cortical organization, and they suggest that the implementation of higher-order motion processing evolved along similar lines in the cat and monkey visual cortex.
KW - Animals
KW - Brain Mapping
KW - Cats
KW - Cell Count
KW - Models, Neurological
KW - Motion
KW - Visual Cortex
KW - Visual Pathways
KW - Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
KW - Comparative Study
KW - Journal Article
KW - Research Support, Non-U.S. Gov't
U2 - 10.1111/j.1460-9568.2005.04232.x
DO - 10.1111/j.1460-9568.2005.04232.x
M3 - SCORING: Journal article
C2 - 16101750
VL - 22
SP - 681
EP - 696
JO - EUR J NEUROSCI
JF - EUR J NEUROSCI
SN - 0953-816X
IS - 3
ER -
