Brain Centres (brain + centre)

Distribution by Scientific Domains

Selected Abstracts

The mushroom bodies , prominent brain centres of arthropods and annelids with enigmatic evolutionary origin

ACTA ZOOLOGICA, Issue 1 2010
Rudi Loesel
Abstract Loesel, R. and Heuer, C.M. 2010. The mushroom bodies , prominent brain centres of arthropods and annelids with enigmatic evolutionary origin. ,Acta Zoologica (Stockholm) 91: 29,34 Mushroom bodies (MBs) are the most prominent and conspicuous neuropils in the brain of arthropods, onychophorans and vagile polychaete annelids but have not been described in any other animal group with complex brain architecture. Due to a number of unique neuroanatomical characters MBs can easily be identified and distinguished from other brain centres. However, their evolutionary origin and the question whether MBs are homologous structures is still under debate. This paper will briefly summarize the available morphological data and their implications with respect to the molecular evidence on early metazoan radiation. Unraveling the origin of MBs is an example of the challenges neurophylogenists will face in the future, especially so since it will signify a major step towards reconstructing early metazoan brain evolution. [source]

Expression of ephrin-A2 in the superior colliculus and EphA5 in the retina following optic nerve section in adult rat

J. Rodger
Abstract The vertebrate retina projects topographically to visual brain centres. In the developing visual system, gradients of ephrins and Eph receptors play a role in defining topography. At maturity, ephrins but not Ephs are downregulated. Here we show that optic nerve section in adult rat differentially regulates the expression of ephrin-A2 in the superior colliculus (SC) and of EphA5 in the retina. Expression was quantified immunohistochemically; ephrin-A2 levels were also estimated by semiquantitative reverse transcriptase polymerase chain reaction. In the normal SC, ephrin-A2 was expressed at low levels. At 1 month, levels of protein and of mRNA were upregulated across the contralateral SC giving rise to an increasing rostro-caudal gradient. At 6 months, levels had fallen but a gradient remained. In the retina of normal animals, EphA5 was expressed as an increasing naso-temporal gradient. By 1 month, expression was decreased in far temporal retina, resulting in a uniform expression across the naso-temporal axis. We suggest that denervation-induced plastic changes within the SC modify expression of these molecules. [source]


BIOETHICS, Issue 6 2009
ABSTRACT Informed consent is the practical expression of the doctrine of autonomy. But the very idea of autonomy and conscious free choice is undercut by the view that human beings react as their unconscious brain centres dictate, depending on factors that may or may not be under rational control and reflection. This worry is, however, based on a faulty model of human autonomy and consciousness and needs close neurophilosophical scrutiny. A critique of the ethics implied by the model takes us towards a ,care of the self' view of autonomy and the subject's attunement to the truth as the crux of reasoning rather than the inner mental/neural state views of autonomy and human choice on offer at present. [source]