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Biomedical subjects

R E Baker

Publications and source records attributed to R E Baker.

106 records · Page 6Linked to original sources
PubMed1968

Neuronal specification of cutaneous nerves through connections with skin grafts in the frog.

Skin grafts were rotated 180 degrees in frog tadpoles. After metamorphosis, cutaneous reflexes were tested, and the receptive fields of cutaneous nerves were mapped electrophysiologically. Accurately localized limb movements were elicited by mechanical stimulation of normal skin, or of dorsal skin reimplanted on the back after 180-degree rotation. Reflexes misdirected to the original site of the stimulated skin were elicited from dorsoventrally inverted grafts, but not from anteroposteriorly inverted grafts. In most cases, the local nerves supplied the grafts, and each nerve entered the skin within its own receptive field. This observation eliminated the possibility that misdirected reflexes were due to selective regrowth of cutaneous nerves. We concluded that cutaneous nerves formed central synaptic associations which were specified by their new terminal connections with grafted skin.

Action Potentials↗
PubMedDate not supplied

Cutaneous receptive field enlargement following skin-grafting in the frog, D. pictus.

Misdirected wiping responses occur in Discoglossus pictus frogs when skin-grafted early in larval life. Cutaneous receptive fields (CRF) for various peripheral nerve branches were mapped electrophysiologically in control and skin-grafted frogs. The ventrolateral nerve branch (VL) frequently provided innervation for significant areas of dorsal skin in both control and skin-grafted animals. Although the VL crossed over onto dorsal skin areas in some skin-grafted frogs giving rise to misdirected reflexes, these dorsal extensions frequently failed to include all skin areas from which the maladaptive reflexes could be elicited. It was concluded that misdirected reflexes are mediated via dorsal nerve branches occupying normal mid-dorsal areas of the back.

Abdomen↗
PubMedDate not supplied

Receptive fields of cutaneous mechanoceptive neurons in the frog, Discoglossus pictus, following skin transplantation at larval stages.

The receptive fields of individual spinal ganglion cells were mapped in frogs in which a large patch of belly skin had been transplanted to the back prior to metamorphosis. Wiping reflexes aimed at the belly could be elicited both from regenerated normal and transplanted belly skin. We concluded that the sensory neurons mediating misdirected responses could not be the same ones as those mediating normal wipes, since unit receptive fields were either on normal or on grafted belly skin, but never both. A proposed mechanism for explaining the origin of cutaneous reflex connections on the basis of selective innervation of peripheral tissues could hereby be discarded.

Animals↗
PubMedDate not supplied

Post-mortem brain tissue cultures from elderly control subjects and patients with a neurodegenerative disease.

Aging may be viewed as a progressive loss of normal biological function. Due to complex genetic and environmental interactions, the sequence of functional impairment shows a high degree of individual variability. In humans life style and health care have an additional influence on the aging process. To study aging and age-related disorders of the human nervous system, brain tissue that has undergone aging and pathological alterations can provide valuable study material. Recently, we have shown that adult human postmortem brain tissue can be cultured and experimentally manipulated. This approach permits the study of cellular aspects of human neuronal aging and neurodegenerative processes and complements those existing research methods such as in vivo imaging (MRI, PET, etc.) and fixed or frozen postmortem brain tissue examination.

Aged↗