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The Study of Passive Membrane Properties and Morphology Reveals Neuronal Differences Along the Sagittal Axis of the Ventral Periaqueductal Grey Matter
Author(s) -
Sánchez D.,
Armengol J. A.,
Ribas J.
Publication year - 1990
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1990.tb00025.x
Subject(s) - sagittal plane , anatomy , grey matter , lucifer yellow , coronal plane , biocytin , periaqueductal gray , neuroscience , chemistry , biology , biophysics , electrophysiology , midbrain , gap junction , intracellular , central nervous system , microbiology and biotechnology , medicine , white matter , magnetic resonance imaging , radiology
The membrane properties of the neurons located in the ventral part of the periaqueductal grey (PAG) of the guinea‐pig were studied using an in vitro slice preparation. Cells had low values of resting membrane potential (−53.3 ± 1.3 mV, mean ± standard error), high input resistance (195.5 ± 16.2 MΩ) and moderate values of membrane time constant (12.6 ± 0.7 ms). The last two parameters changed as recordings were made along the sagittal axis, higher values corresponding to the more rostral cells. Three main neuronal types—fusiform, triangular and stellate—were found in the ventral PAG using intracellular injection of Lucifer yellow. A study of the cell number and cell density was carried out in coronal and sagittal sections of the ventral PAG. This analysis showed a clear gradient of size in this region arising from the gradual disappearance of large (17 to 40 μm) neurons in the caudorostral direction. The neuronal density also increased in this direction. Therefore, some electrotonic and morphological parameters differ along the sagittal axis. These findings suggest a larger neuronal heterogeneity of the caudal part of the PAG, and might contribute to a functional segregation of this region.