Mv. Sanchezvives et al., ARE THE INTERLAMINAR ZONES OF THE FERRET DORSAL LATERAL GENICULATE-NUCLEUS ACTUALLY PART OF THE PERIGENICULATE NUCLEUS, The Journal of neuroscience, 16(19), 1996, pp. 5923-5941
The ferret dorsal lateral geniculate nucleus (LGNd) contains interneur
ons within the interlaminar zones situated between the laminae corresp
onding to the ipsi- and contralateral eyes. We found that a subset of
these neurons exhibits electrophysiological properties similar to thos
e 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 hyperp
olarizing current pulse. These ''PGN-like'' interlaminar interneurons
innervated restricted regions of the A-laminae, inhibited thalamocorti
cal cells through GABA(A), and perhaps GABA(B), receptors, and were ex
cited 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 spin
dle waves and other network oscillations. Pharmacologically, PGN-like
interlaminar interneurons were also similar to PGN neurons: both gener
ated a prolonged depolarization in response to the local application o
f serotonin, 1S,3R-ACPD, and CCK8S, and a rapid depolarization followe
d by a more prolonged hyperpolarization in response to acetylcholine.
Examination of parvalbumin and calbindin staining in the ferret LGNd r
evealed that both PGN and a subset of interlaminar neurons were parval
bumin-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 in
terlaminar zone in between laminae A and Al and Al and C in the ferret
LGNd possesses a cell type that is electrophysiologically, pharmacolo
gically, anatomically, immunocytochemically, and functionally similar
to neurons in the PGN.