Volume 16, Number 19,
Issue of October 1, 1996
pp. 5923-5941
Copyright ©1996 Society for Neuroscience
Are the Interlaminar Zones of the Ferret Dorsal Lateral
Geniculate Nucleus Actually Part of the Perigeniculate Nucleus?
Received May 22, 1996; revised July 1, 1996; accepted July 8, 1996.
Maria V. Sanchez-Vives1, ,
Thierry Bal2, ,
Uhnoh Kim1,
Marcus von
Krosigk3, and
David A. McCormick1
1 Section of Neurobiology, Yale University School of
Medicine, New Haven, Connecticut 06510, 2 Institut Alfred
Fessard, Centre National de la Recherche Scientifique, Gif Sur Yvette
Cedex 91198, France, and 3 Kinsmen Laboratory of
Neurological Research, University of British Columbia, Vancouver,
British Columbia, Canada V6T 1W5
The ferret dorsal lateral geniculate nucleus (LGNd) contains
interneurons within the interlaminar zones situated between the laminae
corresponding to the ipsi- and contralateral eyes. We found that a
subset of these neurons exhibits electrophysiological properties
similar to those previously reported for perigeniculate (PGN) neurons,
including the generation of rhythmic sequences of rebound low-threshold
Ca2+ spikes at a frequency of 1-4 Hz after the
intracellular injection of a hyperpolarizing current pulse. These
``PGN-like'' interlaminar interneurons innervated restricted regions
of the A-laminae, inhibited thalamocortical cells through
GABAA, and perhaps GABAB, receptors, and were
excited by axon collaterals from thalamocortical cells. This reciprocal
relationship is identical to that formed by PGN cells and allowed the
PGN-like interlaminar neurons to participate in the generation of
spindle waves and other network oscillations. Pharmacologically,
PGN-like interlaminar interneurons were also similar to PGN neurons:
both generated a prolonged depolarization in response to the local
application of serotonin, 1S,3R-ACPD, and
CCK8S, and a rapid depolarization followed by a more prolonged
hyperpolarization in response to acetylcholine.
Examination of parvalbumin and calbindin staining in the ferret LGNd
revealed that both PGN and a subset of interlaminar neurons were
parvalbumin-positive. In contrast, calbindin-positive cells were
relatively absent in the PGN and sparsely present in the interlaminar
zones, but were numerous in the A and C laminae. Our results indicate
that the interlaminar zone in between laminae A and A1 and A1 and C in
the ferret LGNd possesses a cell type that is electrophysiologically,
pharmacologically, anatomically, immunocytochemically, and functionally
similar to neurons in the PGN.
Key words:
spindle waves;
GABA;
thalamus;
interneurons;
thalamic
reticular nucleus;
thalamocortical cell collaterals
Previous Article | Next Article
