| Cell type (class) | Nomenclature (Acronym) |
Definition | Relation of non-bursting LTS neuron |
| Annotation | Reference |
Collator |
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| PVN pre-autonomic type C neuron | Stern (Stern) | PVN preautonomic type C neurones accounted for 23% of recorded neurones, with the great majority of them (83 %) located in the PaPo subnucleus (Fig. 3C). They had a mean cross-sectional soma area of 165.4 ± 40 µm2, with 3.1± 0.2 primary dendrites, which gave rise to 7.9 ± 0.9 branches (n = 17). Similar to the other neuronal types, dendrites were often varicose and tended to approach the walls of the 3V. In two cases, dendrites of type C neurones were observed to cross to the contralateral
PVN (see Fig. 1D). The TDL, MDL and MPL of type C neurones were 2168.2 ± 750 µm, 692.9 ± 220 µm and 348.5 ± 86 µm, respectively. In contrast to type A and B neurones, in the majority of type C neurones (10/17, 60%), axons arose from the soma (Fig. 3C1 and C2). However, the incidence of axon origin was not significantly different between cell types (P = 0.1, x2 test). | partial correspondence | | LTSs with variable shapes and amplitudes, ranging from small-amplitude'humps' to long-lasting plateaus, were observed in 35/41 (84%) type A, 20/20 (100%) type B and 15/18 (85%) type C neurones. The incidence of LTSs was not significantly different among neuronal types. | Stern J.E. | Mihail Bota |
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| PVN pre-autonomic type B neuron | Stern (Stern) | PVN preautonomic type B neurones were located exclusively in the PaPo subnucleus, and accounted for 25 % of the recorded neurones (Fig. 3B). They had a mean crosssectional soma area of 188.7 ± 4.2 µm2, which was not significantly different from the other PVN pre-autonomic neurones (P > 0.5, one-way ANOVA). A morphometric analysis of reconstructed neurones revealed that type B pre-autonomic neurones (n = 15) had the most complex dendritic arborization, as compared to the other neuronal
types. Type B neurones had 3.8 ± 0.1 primary dendrites, which gave rise to 10.7 ± 1.9 branches (both parameters were significantly larger than the other neuronal types, P < 0.001 and P < 0.02, respectively, one-way ANOVA, Fig. 4). The TDL was also significantly larger than in the other neuronal types (5329.3 ± 1500 µm, P < 0.02, oneway ANOVA, Fig. 4). The MDL and MPL were 778.6 ± 310.7 µm and 390.5 ± 104.4 µm, respectively (not different from the other neuronal types). Similar to type A neurones, in the majority of cases (12/15, 80 %) axons arose from a primary dendrite, at a mean distance from the soma of 38 ± 6 µm. | partial correspondence | | LTSs with variable shapes and amplitudes, ranging from small-amplitude'humps' to long-lasting plateaus, were observed in 35/41 (84%) type A, 20/20 (100%) type B and 15/18 (85%) type C neurones. The incidence of LTSs was not significantly different among neuronal types. | Stern J.E. | Mihail Bota |
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| PVN pre-autonomic type A neuron | Stern (Stern) | PVN preautonomic type A neurones were located exclusively in the PaV subnucleus and were the most common cell type labelled, accounting for 52 % of all labelled neurones in the PVN (Fig. 3A). They had a mean cross-sectional soma area of 134.8 ± 15.4 µm2. Dendrites were often varicose, and short spinous processes were occasionally observed. A
common observation (also found for the other neuronal
types) was that distal dendritic branches extended
beyond the boundaries of the subnucleus and tended to
approach the walls of the 3V. A morphometric analysis
of reconstructed neurones showed that type A neurones
(n = 33) had 2.7 ± 0.1 primary dendrites, which gave rise
to 6.4 ± 0.7 branches. The TDL, MDL and mean path
length (MPL) were 2093.7 ± 215.8 µm, 766.6 ± 91.4 µm
and 399.7 ± 33.2 µm, respectively (see Fig. 4, for
comparison with the other neuronal types). Axons were
identified by their thinner diameter and beaded
appearance...axons [...] could be traced for several hundred
micrometres, running laterally or ventrolaterally towards the lateral hypothalamic area. In 25/33 (78 %) type A
neurones, axons arose from a primary dendrite at a mean
distance from the soma of 41± 5 µm (Fig. 3A1 and A2).
In the remaining type A neurones, axons arose directly
from the soma. | partial correspondence | | LTSs with variable shapes and amplitudes, ranging from small-amplitude'humps' to long-lasting plateaus, were observed in 35/41 (84%) type A, 20/20 (100%) type B and 15/18 (85%) type C neurones. The incidence of LTSs was not significantly different among neuronal types. | Stern J.E. | Mihail Bota |
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| type II PVN neuron | Tasker and Dudek (TD) | Type II neurones tended to have smaller soma diameters (10-25,tm) and more highly branched dendritic arbors, with two to four primary dendrites giving rise to secondary branches (Fig. 13B). Type I and type II neurones generally
had elongated, bidirectional dendritic orientations. Type II neurones were located within the PVN and showed electrophysiological properties which were distinct from those of type I neurones and SON magnocellular neurones. The principal distinguishing characteristic of these cells was their capacity to generate a small low-threshold potential, similar to that seen in some neurones of the neocortex (Friedman & Gutnick, 1987), the dorsal raphe nucleus (Burlhis & Aghajanian, 1987) and in dopamine-containing regions of the midbrain (Grace & Onn, 1989). The heterogeneity seen in the electrical properties of type II cells (e.g. low-threshold potentials of various amplitudes, inconsistent I-V relations across cells and differences in bursting behaviour) suggests that this group of neurones consists of more than one cell type. This electrophysiological heterogeneity is consistent with the diversity of anatomical and functional cell types that make up the parvocellular populations of the PVN (Armstrong et al. 1980; van den Pol, 1982; Swanson & Sawchenko, 1983). | synonym | | Another PVN neuronal population was composed of non-bursting LTS cells; these conformed with type-II electrophysiological criteria (Tasker and Dudek, '91) by having relatively small low-threshold potentials that usually generated only one or two action potentials (Fig. 3A). | Hoffman N.W, Tasker J.G. & Dudek F.E. | Mihail Bota |
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| descending neuron | Swanson (Swanson) | Collator note: those neurons that project to the autonomic centers located in the spinal cord and in the dorsal medulla, and are located in the hypothalamus. | partially corresponds | | Approximately 75% of cells that were negative for fluoro-gold displayed an LTS and expressed a relatively large T-current. This finding is consistent with that of a recent study reporting that PVN preautonomic neurones backfilled by tracer injection in the brainstem expressed an LTS (10). | Luther J.A., Daftary S.S., Boudaba C., Gould G.C., Halmos K.CS. & Taker J.G. | Mihail Bota |
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