Ps. Buckmaster et Pa. Schwartzkroin, PHYSIOLOGICAL AND MORPHOLOGICAL HETEROGENEITY OF DENTATE GYRUS-HILUS INTERNEURONS IN THE GERBIL HIPPOCAMPUS IN-VIVO, European journal of neuroscience, 7(6), 1995, pp. 1393-1402
A variety of morphological types of dentate gyrus/hilus interneurons h
ave been described, but little is known about their corresponding phys
iological characteristics. To address this issue, intracellular respon
ses to current injection and perforant path stimulation were obtained
from putative dentate interneurons in anaesthetized adult gerbils. Our
sample of interneurons showed heterogeneity in their intrinsic physio
logical characteristics and spike thresholds to perforant path stimula
tion, suggesting the existence of distinct physiologically-defined cla
sses. 'Fast-spiking' interneurons had a low threshold to perforant pat
h stimulation, whereas 'slow-spiking' interneurons responded with pred
ominantly inhibitory potentials. In several cases, cells were intracel
lularly labelled with biocytin for visualization. Interneurons with di
fferent physiological traits had distinct morphological features. Thes
e results confirm that, as in hippocampus proper, morphologically iden
tifiable interneurons in the dentate hilus show electrophysiological f
eatures that are likely to reflect functionally specific roles in info
rmational processing.