Posts

Showing posts from 2009

Visualising Connections in the Human Brain

Image
Most of us are familiar with pictures from magnetic resonance imaging (MRI) of the human brain; indeed, these black-and-white images have achieved almost iconic status at this stage. From popular television programmes, and regrettably from common experience, the use of these images to detect lesions, such as tumours or the effects of stroke, is well known.

Classic MRI can distinguish grey and white matter based on their different cellular composition but cannot go very far beyond that, because all the white matter has effectively the same contrast. This makes traditional MRI of limited use in examining connectivity between areas of the brain, except at a very gross level (such as whether the corpus callosum exists, for example). However, with a few modifications, MRI can be applied to non-invasively interrogate connectivity in the living human brain, with ever-increasing sensitivity. These new techniques are opening up avenues of investigation that have not just tremendous clinica…

Cell Fate and Connectivity Intertwined

Image
The traditional view of neural development is linear. First, the embryo and neurectoderm are patterned by secreted factors, which establish cell fates among progenitors and then differentiated neurons, encoded by combinations of transcription factors. The fate or phenotype of each neuron includes the expression of the specific set of ion channels, neurotransmitters and receptors that determine its physiological function. It also includes expression of a particular repertoire of guidance receptors and surface molecules regulating connectivity, which enable axonal pathfinding and target selection. The processes that establish connectivity are usually thought of as happening after the fate of neurons and their targets have been established. This linear paradigm, from patterning to differentiation to connection, has been increasingly challenged by studies from both invertebrate and vertebrate systems.

A number of studies have shown that incoming axons can regulate the proliferation an…

Hot News in The Genetics of Schizophrenia

Image
Schizophrenia is a common and devastating disorder, involving stable impairments in a wide range of cognitive, sensory and motor domains, as well as fluctuating episodes of psychosis, characterised by disordered thoughts, hallucinations and delusions. Though it tends to emerge as a full-blown disorder in late adolescence or early adulthood, a wealth of evidence supports the model that it is caused by disturbances in neural development at much earlier time-points, including prenatally. Recent neuroimaging analyses have supported psychological theories of schizophrenia as a “disconnection syndrome”, showing altered structural and functional connectivity between (and also within) many regions of the brain. Schizophrenia can thus be thought of as the result of alterations in brain wiring, and these alterations are, in turn, caused by mutations.

There is strong and consistent evidence from twin, adoption and family studies that schizophrenia is highly heritable. Though this fact is no…

Nature, nurture and noise

Image
The question of what makes each of us the persons we are has occupied philosophers, writers and daydreamers for millennia but has been open to scientific inquiry over a far shorter time. The answer clearly lies in the brain and, somehow, in how it is “wired” (whether that refers to the amount or type of connections between different brain areas or to differences in how circuits function). But differences in brain wiring could be either innate or due to experience or environmental effects. This has been famously framed, by Galton originally, as a clash of nature versus nurture. The inspiration for this phrase may have come from Shakepseare’s The Tempest, in which Prospero refers to Caliban as a "A devil, a born devil, on whose nature / Nurture can never stick". That line encapsulates the notion of an innate character that is resistant to extrinsic influences, especially efforts to change aspects of a person’s personality – an idea which anyone who has children may find …

welcome

Image
Welcome to the Wiring the Brain blog.  The purpose of this site is to allow researchers (or anyone else who is interested) to discuss research developments in various fields related to how the brain gets wired, how it varies and what effects this has.  These fields will include developmental neurobiology, molecular and cellular neuroscience, systems neuroscience, cognitive science, psychology, psychiatric genetics and others.  Recent papers or specific hypotheses will be highlighted for discussion.