Rw. Rhoades et al., ALTERATIONS IN BRAIN-STEM AND CORTICAL ORGANIZATION OF RATS SUSTAINING PRENATAL VIBRISSA FOLLICLE LESIONS, Somatosensory & motor research, 11(1), 1994, pp. 1-17
Vibrissa follicles were cauterized in late fetal or newborn rats to de
termine whether the relationships between brainstem and cortical chang
es observed after neonatal peripheral damage would also be obtained wh
en vibrissa follicles were cauterized earlier in development. Vibrissa
follicles were cauterized between embryonic day 15 (E-15) and die day
of birth (P-0). The vibrissa-related representation in the brainstem
was examined with cytochrome oxidase histochemistry, and that in the c
ortex was evaluated with either serotonin immunocytochemistry or anter
ograde labeling with Di-I when animals reached 6-8 days of age. There
was a significant relationship between the ages at which lesions were
carried out and the extent to which the representations of undamaged v
ibrissa follicles were altered in the brainstem and cortex. Peripheral
lesions carried out between E-15 and E-18 resulted in significant inc
reases in the cross-sectional areas of the patches corresponding to th
e undamaged vibrissa follicles in both the brainstem and cortex. Lesio
ns at later ages resulted in significant increases only in the cortex.
In some animals that sustained peripheral damage on E-20 and all of t
hose that received lesions on P-0, there were aggregates of labeling i
n cortex that had no counterpart in the brainstem. Prenatal, but not p
ostnatal, vibrissa follicle damage also reduced the overall dimensions
of the cortical region devoted to the representation of these recepto
r organelles. Finally, there was a strong negative correlation between
the magnitude of peripheral lesions (i.e., the number of vibrissa fol
licles ablated) and the extent of the reorganization in the brainstem
and cortex.