The evolution of neocortex in primates culminating in man is the most remarkable transformation in all of evolutionary history. In the traditional view the expansion of cortex was attributed to the increase in association areas. This conclusion has been reexamined over the past 15 years by the study of a graded series of species including opossum, hedgehog, tree shrew, and galago. These studies have shown that there is little or no association cortex as far up the scale as the prosimian. Instead the neocortex is composed chiefly of three extensive sensory fields: auditory, somatic and visual. The present proposal is aimed at uncovering the principles underlying the organization of these fields. At a first approximation it would seem that some principles are common to all fields. Each cortical field is the target of parallel pathways that differ in fiber size, relay in different thalamic nuclei, terminate in different layers of cortex, and to some extent terminate in different areas of the field.
The aim of the research is to discover the functional significance of the various pathways by the behavioral deficit method. Because pathways overlap in a given cortical area, it is not easy to eliminate a pathway selectively by ablating a cortical area. Experiments are proposed in which separate paths are selectively destroyed. These studies will cast light on the role of the striate cortex and superior colliculus in vision. The evolution of cortex between the stages represented by prosimians and simians will be studied by adding the owl monkey to the series of species.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH004849-24
Application #
3374551
Study Section
(BPNB)
Project Start
1976-12-01
Project End
1985-11-30
Budget Start
1984-12-01
Budget End
1985-11-30
Support Year
24
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Duke University
Department
Type
Schools of Arts and Sciences
DUNS #
071723621
City
Durham
State
NC
Country
United States
Zip Code
27705
Conley, M; Friederich-Ecsy, B (1993) Functional organization of the ventral lateral geniculate complex of the tree shrew (Tupaia belangeri): I. Nuclear subdivisions and retinal projections. J Comp Neurol 328:1-20
Diamond, I T; Fitzpatrick, D; Schmechel, D (1993) Calcium binding proteins distinguish large and small cells of the ventral posterior and lateral geniculate nuclei of the prosimian galago and the tree shrew (Tupaia belangeri). Proc Natl Acad Sci U S A 90:1425-9
Conley, M; Friederich-Ecsy, B (1993) Functional organization of the ventral lateral geniculate complex of the tree shrew (Tupaia belangeri): II. Connections with the cortex, thalamus, and brainstem. J Comp Neurol 328:21-42
Diamond, I T; Fitzpatrick, D; Conley, M (1992) A projection from the parabigeminal nucleus to the pulvinar nucleus in Galago. J Comp Neurol 316:375-82
Conley, M; Wilson, K F (1992) Dendritic organization of class II (inter)neurons in the dorsal lateral geniculate nucleus of the tree shrew: observations based on Golgi, immunocytochemical, and biocytin methods. J Comp Neurol 319:51-65
Diamond, I T; Conley, M; Fitzpatrick, D et al. (1991) Evidence for separate pathways within the tecto-geniculate projection in the tree shrew. Proc Natl Acad Sci U S A 88:1315-9
Raczkowski, D; Fitzpatrick, D (1990) Terminal arbors of individual, physiologically identified geniculocortical axons in the tree shrew's striate cortex. J Comp Neurol 302:500-14
Fitzpatrick, D; Raczkowski, D (1990) Innervation patterns of single physiologically identified geniculocortical axons in the striate cortex of the tree shrew. Proc Natl Acad Sci U S A 87:449-53
Conley, M; Raczkowski, D (1990) Sublaminar organization within layer VI of the striate cortex in Galago. J Comp Neurol 302:425-36
Raczkowski, D; Fitzpatrick, D (1989) Organization of cholinergic synapses in the cat's dorsal lateral geniculate and perigeniculate nuclei. J Comp Neurol 288:676-90

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