Effects of large-scale limb deafferentation on the morphological and physiological organization of the forepaw barrel subfield (FBS) in somatosensory cortex (SI) in adult and neonatal rats

Phillip P. Pearson, Cheng X. Li, Robert Waters

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The physiological representation of the shoulder and surrounding body was examined in layer IV of somatosensory cortex (SI) in rats that had underground removal of the forelimb, either as newborns on postnatal day three (PND-3) or as adults (at least 8 weeks of age). Electrophysiological recordings were used to map the shoulder and body representations (physiological map), and the mitochondria marker, cytochrome oxidase (CO), was used to visualize recording sites in barrel and barrel-like structures (morphological map) in layer IV of deafferents and intact controls. The SI shoulder representation lies in a nebulously stained region that lies posterior to the forearm, wrist, and forepaw representations; the latter region is associated with the well-defined forepaw barrel subfield (FBS). The major findings are: (1) the shoulder is represented as a single zone located at the posterior extent of the SI body map in intact rats; (2) limb deafferentation in adult or neonatal rats that were physiologically mapped 6-16 weeks post-amputation resulted in two or more islets of 'new' representation of the shoulder in the FBS in addition to the representation of the 'original' shoulder in the posterior part of the body map; (3) deafferentations made in neonatal rats, physiologically mapped as adults, had a significantly greater (Mann-Whitney U) amount of 'new' cortical representation within the FBS than did rats deafferented as adults; (4) fewer unresponsive sites in the FBS were found for neonate deafferents than for adult deafferents; (5) evoked response latencies following electrical stimulation of the shoulder were shortest for cortical sites within the 'original' shoulder representation in intact controls, and latencies recorded at the 'original' shoulder representation in deafferents were also shorter than latencies recorded in 'new' shoulder representations in both groups of deafferents; and (6) morphological maps of the FBS were altered in neonate deafferents to the extent that the barrel structure was poorly formed, as exemplified by the absence of the four mediolateral running bands; however, the overall ovoid shape of the FBS was still apparent, but not as sharply defined as for intact controls or adult deafferents. Possible mechanisms for reorganization following large-scale deafferentation are discussed.

Original languageEnglish (US)
Pages (from-to)315-331
Number of pages17
JournalExperimental Brain Research
Volume128
Issue number3
DOIs
StatePublished - Oct 5 1999

Fingerprint

Somatosensory Cortex
Extremities
Organizations
Newborn Infant
Forelimb
Body Image
Electron Transport Complex IV
Wrist
Amputation
Human Body
Forearm
Running
Electric Stimulation
Reaction Time
Mitochondria

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

@article{4cf7e309a20142a6ad946626e02874ed,
title = "Effects of large-scale limb deafferentation on the morphological and physiological organization of the forepaw barrel subfield (FBS) in somatosensory cortex (SI) in adult and neonatal rats",
abstract = "The physiological representation of the shoulder and surrounding body was examined in layer IV of somatosensory cortex (SI) in rats that had underground removal of the forelimb, either as newborns on postnatal day three (PND-3) or as adults (at least 8 weeks of age). Electrophysiological recordings were used to map the shoulder and body representations (physiological map), and the mitochondria marker, cytochrome oxidase (CO), was used to visualize recording sites in barrel and barrel-like structures (morphological map) in layer IV of deafferents and intact controls. The SI shoulder representation lies in a nebulously stained region that lies posterior to the forearm, wrist, and forepaw representations; the latter region is associated with the well-defined forepaw barrel subfield (FBS). The major findings are: (1) the shoulder is represented as a single zone located at the posterior extent of the SI body map in intact rats; (2) limb deafferentation in adult or neonatal rats that were physiologically mapped 6-16 weeks post-amputation resulted in two or more islets of 'new' representation of the shoulder in the FBS in addition to the representation of the 'original' shoulder in the posterior part of the body map; (3) deafferentations made in neonatal rats, physiologically mapped as adults, had a significantly greater (Mann-Whitney U) amount of 'new' cortical representation within the FBS than did rats deafferented as adults; (4) fewer unresponsive sites in the FBS were found for neonate deafferents than for adult deafferents; (5) evoked response latencies following electrical stimulation of the shoulder were shortest for cortical sites within the 'original' shoulder representation in intact controls, and latencies recorded at the 'original' shoulder representation in deafferents were also shorter than latencies recorded in 'new' shoulder representations in both groups of deafferents; and (6) morphological maps of the FBS were altered in neonate deafferents to the extent that the barrel structure was poorly formed, as exemplified by the absence of the four mediolateral running bands; however, the overall ovoid shape of the FBS was still apparent, but not as sharply defined as for intact controls or adult deafferents. Possible mechanisms for reorganization following large-scale deafferentation are discussed.",
author = "Pearson, {Phillip P.} and Li, {Cheng X.} and Robert Waters",
year = "1999",
month = "10",
day = "5",
doi = "10.1007/s002210050852",
language = "English (US)",
volume = "128",
pages = "315--331",
journal = "Experimental Brain Research",
issn = "0014-4819",
publisher = "Springer Verlag",
number = "3",

}

TY - JOUR

T1 - Effects of large-scale limb deafferentation on the morphological and physiological organization of the forepaw barrel subfield (FBS) in somatosensory cortex (SI) in adult and neonatal rats

AU - Pearson, Phillip P.

AU - Li, Cheng X.

AU - Waters, Robert

PY - 1999/10/5

Y1 - 1999/10/5

N2 - The physiological representation of the shoulder and surrounding body was examined in layer IV of somatosensory cortex (SI) in rats that had underground removal of the forelimb, either as newborns on postnatal day three (PND-3) or as adults (at least 8 weeks of age). Electrophysiological recordings were used to map the shoulder and body representations (physiological map), and the mitochondria marker, cytochrome oxidase (CO), was used to visualize recording sites in barrel and barrel-like structures (morphological map) in layer IV of deafferents and intact controls. The SI shoulder representation lies in a nebulously stained region that lies posterior to the forearm, wrist, and forepaw representations; the latter region is associated with the well-defined forepaw barrel subfield (FBS). The major findings are: (1) the shoulder is represented as a single zone located at the posterior extent of the SI body map in intact rats; (2) limb deafferentation in adult or neonatal rats that were physiologically mapped 6-16 weeks post-amputation resulted in two or more islets of 'new' representation of the shoulder in the FBS in addition to the representation of the 'original' shoulder in the posterior part of the body map; (3) deafferentations made in neonatal rats, physiologically mapped as adults, had a significantly greater (Mann-Whitney U) amount of 'new' cortical representation within the FBS than did rats deafferented as adults; (4) fewer unresponsive sites in the FBS were found for neonate deafferents than for adult deafferents; (5) evoked response latencies following electrical stimulation of the shoulder were shortest for cortical sites within the 'original' shoulder representation in intact controls, and latencies recorded at the 'original' shoulder representation in deafferents were also shorter than latencies recorded in 'new' shoulder representations in both groups of deafferents; and (6) morphological maps of the FBS were altered in neonate deafferents to the extent that the barrel structure was poorly formed, as exemplified by the absence of the four mediolateral running bands; however, the overall ovoid shape of the FBS was still apparent, but not as sharply defined as for intact controls or adult deafferents. Possible mechanisms for reorganization following large-scale deafferentation are discussed.

AB - The physiological representation of the shoulder and surrounding body was examined in layer IV of somatosensory cortex (SI) in rats that had underground removal of the forelimb, either as newborns on postnatal day three (PND-3) or as adults (at least 8 weeks of age). Electrophysiological recordings were used to map the shoulder and body representations (physiological map), and the mitochondria marker, cytochrome oxidase (CO), was used to visualize recording sites in barrel and barrel-like structures (morphological map) in layer IV of deafferents and intact controls. The SI shoulder representation lies in a nebulously stained region that lies posterior to the forearm, wrist, and forepaw representations; the latter region is associated with the well-defined forepaw barrel subfield (FBS). The major findings are: (1) the shoulder is represented as a single zone located at the posterior extent of the SI body map in intact rats; (2) limb deafferentation in adult or neonatal rats that were physiologically mapped 6-16 weeks post-amputation resulted in two or more islets of 'new' representation of the shoulder in the FBS in addition to the representation of the 'original' shoulder in the posterior part of the body map; (3) deafferentations made in neonatal rats, physiologically mapped as adults, had a significantly greater (Mann-Whitney U) amount of 'new' cortical representation within the FBS than did rats deafferented as adults; (4) fewer unresponsive sites in the FBS were found for neonate deafferents than for adult deafferents; (5) evoked response latencies following electrical stimulation of the shoulder were shortest for cortical sites within the 'original' shoulder representation in intact controls, and latencies recorded at the 'original' shoulder representation in deafferents were also shorter than latencies recorded in 'new' shoulder representations in both groups of deafferents; and (6) morphological maps of the FBS were altered in neonate deafferents to the extent that the barrel structure was poorly formed, as exemplified by the absence of the four mediolateral running bands; however, the overall ovoid shape of the FBS was still apparent, but not as sharply defined as for intact controls or adult deafferents. Possible mechanisms for reorganization following large-scale deafferentation are discussed.

UR - http://www.scopus.com/inward/record.url?scp=0032821454&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0032821454&partnerID=8YFLogxK

U2 - 10.1007/s002210050852

DO - 10.1007/s002210050852

M3 - Article

C2 - 10501804

AN - SCOPUS:0032821454

VL - 128

SP - 315

EP - 331

JO - Experimental Brain Research

JF - Experimental Brain Research

SN - 0014-4819

IS - 3

ER -