The central nervous system of cartilaginous fishes: a neuro-anatomical study based on normal and experimental material

Contains fulltext : mmubn000001_027417492.pdf (publisher's version ) (Open Access)Promotor : R. Nieuwenhuys cum laude103 p

Evolution of the basal ganglia: new perspectives through a comparative approach.

PMCID: PMC1468093The basal ganglia (BG) have received much attention during the last 3 decades mainly because of their clinical relevance. Our understanding of their structure, organisation and function in terms of chemoarchitecture, compartmentalisation, connections and receptor localisation has increased equally. Most of the research has been focused on the mammalian BG, but a considerable number of studies have been carried out in nonmammalian vertebrates, in particular reptiles and birds. The BG of the latter 2 classes of vertebrates, which together with mammals constitute the amniotic vertebrates, have been thoroughly studied by means of tract-tracing and immunohistochemical techniques. The terminology used for amniotic BG structures has frequently been adopted to indicate putative corresponding structures in the brain of anamniotes, i.e. amphibians and fishes, but data for such a comparison were, until recently, almost totally lacking. It has been proposed several times that the occurrence of well developed BG structures probably constitutes a landmark in the anamniote-amniote transition. However, our recent studies of connections, chemoarchitecture and development of the basal forebrain of amphibians have revealed that tetrapod vertebrates share a common pattern of BG organisation. This pattern includes the existence of dorsal and ventral striatopallidal systems, reciprocal connections between the striatopallidal complex and the diencephalic and mesencephalic basal plate (striatonigral and nigrostriatal projections), and descending pathways from the striatopallidal system to the midbrain tectum and reticular formation. The connectional similarities are paralleled by similarities in the distribution of chemical markers of striatal and pallidal structures such as dopamine, substance P and enkephalin, as well as by similarities in development and expression of homeobox genes. On the other hand, a major evolutionary trend is the progressive involvement of the cortex in the processing of the thalamic sensory information relayed to the BG of tetrapods. By using the comparative approach, new insights have been gained with respect to certain features of the BG of vertebrates in general, such as the segmental organisation of the midbrain dopaminergic cell groups, the occurrence of large numbers of dopaminergic cell bodies within the telencephalon itself and the variability in, among others, connectivity and chemoarchitecture. However, the intriguing question whether the basal forebrain organisation of nontetrapods differs essentially from that observed in tetrapods still needs to be answered.Peer reviewe

Evidences for shared features in the organization of the basal ganglia in tetrapods

In a series of recent studies, the organization of the basal ganglia of amphibians, more in particular their connectivity and chemoarchitecture, has been thoroughly analyzed. The pattern of organization found for the amphibian basal ganglia includes dorsal and ventral striatopallidal systems, reciprocal connections between the striatopallidal complex and structures derived from the diencephalic and mesencephalic parts of the basal plate (striatonigral and nigrostriatal projections), and descending pathways from the striatopallidal system to the midbrain tectum and the reticular formation of the brain stem. A comparative analysis of the organization of the basal ganglia in tetrapods strongly supports the notion that a primitive pattern was most likely present in ancestral tetrapods, and that many features can still be recognized in extant amphibians and amniotes

Anatomical substrate of amphibian basal ganglia involvement in visumotor behaviour

PMID:9421170The optic tectum of amphibians is known to play a major role in the control of visually elicited orienting movements, such as prey-catching and avoidance behaviours. The recent finding of a direct striato-tectal connection in the frog Rana perezi prompted us to study in detail the anatomical substrate by which the basal ganglia of amphibians may modulate visuomotor behaviour. Injections of anterograde tracers into the striatum were combined with applications of retrograde tracers in the mid-brain tectum. Apart from a direct striato-tectal connection, at least three indirect pathways were observed, viz. a striato-anterior entopeduncular-tectal pathway, a striato-pretectal-tectal pathway and a striato-tegmento-tectal pathway. The basal ganglia-tectal connections of anurans largely resemble those described for amniotes, but appear to be more extensive. However, a pallio-tectal connection comparable to the cortico-tectal pathways of mammals was not observed in Rana perezi. Therefore, the striatum of anurans, which receives multimodal sensory information, seems to be the sole telencephalic structure that influences the mesencephalic tectum via a direct pathway.This research was supported by grants of the Spanish DGICYT PB96-0606 (A. G.), Spanish FPU Grant (0. M.) and NATO Collaborative Grant CRG 910970. The authors are also grateful to Mr D. de Jong for preparing the photomicrographs.Peer reviewe

Recovery from TPA inhibition of receptor-mediated Ca2+ mobilization is paralleled by down-regulation of protein kinase C-alpha in CHO cells expressing the CCK-A receptor

Contains fulltext : 22867___.PDF (publisher's version ) (Open Access