Five-Minute Stress Relief.com

Neurogenesis

Brain Cells Grow More Than We Ever Knew

Most of were taught in school that while muscles and bones repair and re-grow throughout our lifetime, while the production of new brain cells are formed at the time the nervous system is developing and, for the most part, do not continue growing later on. However, in the last decade, scientists have discovered that brain cells do continue to grow well into middle age in a process called neurogenesis.

Neurogenesis is defined as the process of generating functionally integrated neurons from progenitor cells (including proliferation of neural progenitors, and maturation and functional integration of neuronal progeny into neuronal circuits). At this time, we know that neurogenesis only occurs in two areas of the brain – in the lateral ventricle (in the subventricular zone) and in the hippocampus (the subgranular zone of the dentate gyrus).

Our understanding of adult neurogenesis has progressed significantly over the past decade, from the identity and location of adult neural stem cells, and proliferation and fate specification of neural progenitors, to migration, nerve guidance, neuronal maturation, and synaptic integration of newborn neurons in the adult central nervous system.

The hippocampus (one area of neurogenesis), is, an area of our brain controlling memory and spatial perception. Hippocampal cells are continuously produced in adults as well as the young.

Scientists have been very interested in learning if adult-born cells build their connections with the rest of the brain in a similar way as “pup-born cells,” as this would be of great importance in reversing damage in those individuals with loss of brain function from trauma or degenerative disorders.

While the “how they did it” part is quite complicated, the results were that researchers were able to show that when stimulated, both adult-born and pup-born cells responded similarly in frequency, amplitude, and kinetics. Furthermore, when the researchers studied how both types of cells integrate signals form a variety of inputs and relay that signal to other neurons, both cells functioned in the similar ways – meaning adult-born cells form neural connections identical to neurons developed early in one’s life. These findings raise the possibility for one day being able to repair damaged brain tissue and that endogenous neural stem cells can be mobilized for the replacement of dying neurons in neurodegenerative diseases.

Neuronal Regeneration Occurs After Strokes

In two new medical studies recently published, scientists have been examining the brains of people who died as the result of a stroke (think of a stroke like a heart attack of the brain). At the site of the fatal blood clot (called an infarct), researchers have found in the infarct area of, evidence of neuronal regeneration in tissues (in the form of neuronal precursor cells). This has occurred not only in younger patients with infarction (blood clot), but also even in advanced age patients who had suffered ischemia (reduced blood supply leading to the death of brain cells).

To test their theory, scientists then induced focal strokes in mice and got similar results as with humans. The stroke caused the long-distance migration of thousands of newly born neuroblasts (immature nerve cells) from one area of the brain to the infarct site (the damaged area).

What’s more, the new cells were also joined by new blood vessels forming around them. When the doctors add biochemicals similar to ones produced by the new blood vessels, the quantity of newly formed neurons increased.

© 2009 Five-Minute Stress Relief - All Rights Reserved

Sources: Life and Death of a Neuron National Institute of Neurological Disorders and Stroke (www.ninds.nih.gov) Acute Psychosocial Stress Reduces Cell Survival in Adult Hippocampal Neurogenesis without Altering Proliferation The Journal of Neuroscience 2006 Mar; 27(11): 2734-43 A Neurovascular Niche for Neurogenesis after Stroke The Journal of Neuroscience December 13, 2006, 26(50):13007-13016 Neurogenesis in the Adult Ischemic Brain: Generation, Migration, Survival, and Restorative Therapy Neuroscientist 2005 Oct;11(5):408-1

Print PDF Page for: Neurogenesis