Quantum Jim's Journal: Juvenile cerebellar astrocytoma (repost for posterity)

I am not a doctor. Cerebellar astrocytoma is a form of intracranial cancer which involves brain cells call astrocytes. It is the third most common type of cancer in juveniles. There are four grades of increasing severity defined by the World Health Organization. Juvenile cerebellar astrocytoma rarely leave the cerebellum. It is a section of the brain located near the brainstem and below the occipital lobe. The cerebellum helps direct balance, attention, and complex motor control (particularly involving vision-related feedback). It also helps a person judge the passage of time and is involved in language processing too.

Astrocytes are not neurons. They are star-shaped glial cells that commonly help form the structure of the brain and provide nutrition from blood vessels. Astrocytes are the largest cells in the brain and outnumber neurons by an order of magnitude. Astrocytes help limit the spread cerain toxic neurotransmitters. Through haemodynamic regulation they can also increase blood flow to areas of intense neural activity in the brain. Functional Magnetic Resonance Imaging (fMRI) of those areas helps biologists understand which areas of the brain corrolate with certain thought patterns.

Astrocytes may also play a role in certain types of neuron-to-neuronsignal transmission by isolating or withdrawing from synapses. They can also form a second communication network within the brain by releasing neurotransmitters in response to certain stimulations. However, it is at least several orders of magnitude slower than the neuronal network.

I love google, wikipedia, and especially the library, where I first learned about these things before the world wide web even existed! :-)