Somatotopic organization of forelimb representation in cervical enlargement of raccoon dorsal horn. 1989

B H Pubols, and H Hirata, and L West-Johnsrud
Neurological Sciences Institute, Good Samaritan Hospital and Medical Center, Portland, Oregon 97209.

1. Somatosensory representation of the forelimb in the dorsal horn of spinal segments C5-T2 was examined in 13 North American raccoons anesthetized with pentobarbital sodium. Single- or multiple-unit responses to light mechanical stimulation were recorded at a total of 504 loci, which were subsequently reconstructed from stained, transverse sections. From these, dorsal view maps of forelimb representation in Rexed's laminae III and IV were synthesized. 2. There was a shifting, serial overlap of representations of different forelimb regions in both the rostrocaudal and mediolateral axes of the dorsal horn. The rostrocaudal progression of receptive fields was from preaxial forelimb to forepaw to postaxial forelimb, whereas the mediolateral progression was from the volar glabrous forepaw toward the trunk. 3. Representations of the glabrous surfaces of the digits and palm pads showed considerable overlap, with the digital representations extending more laterally, but the palmar representations extending more rostrally and caudally. One-third of all recording loci were devoted exclusively to glabrous skin representation. 4. Comparison with results of earlier studies in raccoons indicates that representation of a given digit or palm pad is more restricted in rostrocaudal extent in the dorsal horn than in the dorsal roots, and that, compared with various nuclear regions of the dorsal column-medial lemniscal system, the glabrous surfaces of the forepaw are underrepresented in the dorsal horn. 5. The results suggest that there is a dorsoventral modular organization of forelimb representation in the dorsal horn. These wedge-shaped modules from larger aggregates which represent major body subdivisions and which course sinuously in the rostrocaudal dimension.

UI MeSH Term Description Entries
D008297 Male Males
D009333 Neck The part of a human or animal body connecting the HEAD to the rest of the body. Necks
D009424 Nervous System Physiological Phenomena Characteristic properties and processes of the NERVOUS SYSTEM as a whole or with reference to the peripheral or the CENTRAL NERVOUS SYSTEM. Nervous System Physiologic Processes,Nervous System Physiological Processes,Nervous System Physiology,Nervous System Physiological Concepts,Nervous System Physiological Phenomenon,Nervous System Physiological Process,Physiology, Nervous System,System Physiology, Nervous
D010812 Physical Stimulation Act of eliciting a response from a person or organism through physical contact. Stimulation, Physical,Physical Stimulations,Stimulations, Physical
D011821 Raccoons Carnivores of the genus Procyon of the family PROCYONIDAE. Two subgenera and seven species are currently recognized. They range from southern Canada to Panama and are found in several of the Caribbean Islands. Procyon,Procyons,Raccoon
D005260 Female Females
D005552 Forelimb A front limb of a quadruped. (The Random House College Dictionary, 1980) Forelimbs
D000344 Afferent Pathways Nerve structures through which impulses are conducted from a peripheral part toward a nerve center. Afferent Pathway,Pathway, Afferent,Pathways, Afferent
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012867 Skin The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.

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