For many years, neuroscientists have been puzzling over a very basic question: How is it that an area of the brain called the thalamus can drive so much activity so widely throughout the brain?
To explain this, it's necessary to go over some basics. The thalamus is an almond-shaped structure that lies deep in the midline. It receives sensory input from all over the body and connects widely to the sensory cortex. Although its outgoing signals account for only a small percentage of activity received by cortical neurons (around 5%), the thalamus controls most of what goes on in the sensory cortex. The question is, how does it do this?
It was previously believed that it in order for a particular signal to be "heard," a neuron would have to increase its rate of firing order to "drown out" other signals being received from other sources. Now it seems that at least as far as the thalamus is concerned, it's all in the timing.
On the basis of a computer model, a group of neuroscientists from the Salk Institute for Biological Studies have found that for an incoming signal to predominate, only around 30 or so thalamic neurons would have to fire simultaneously. This is in spite of the fact that any given sensory neuron in the cerebral cortex receives input from many different areas (as many as 6,000 signals at any one time).
In other words, if only 30 of those 6,000 signals arrive at the same time from the thalamus, that signal can "drive" much of what goes on. Amazing.
This model is important because it gives scientists a new tool for decoding the basic "language" of the brain, which in turn might lead to new ways of understanding and treating a number of neurological and psychiatric disorders.
To explain this, it's necessary to go over some basics. The thalamus is an almond-shaped structure that lies deep in the midline. It receives sensory input from all over the body and connects widely to the sensory cortex. Although its outgoing signals account for only a small percentage of activity received by cortical neurons (around 5%), the thalamus controls most of what goes on in the sensory cortex. The question is, how does it do this?
It was previously believed that it in order for a particular signal to be "heard," a neuron would have to increase its rate of firing order to "drown out" other signals being received from other sources. Now it seems that at least as far as the thalamus is concerned, it's all in the timing.
On the basis of a computer model, a group of neuroscientists from the Salk Institute for Biological Studies have found that for an incoming signal to predominate, only around 30 or so thalamic neurons would have to fire simultaneously. This is in spite of the fact that any given sensory neuron in the cerebral cortex receives input from many different areas (as many as 6,000 signals at any one time).
In other words, if only 30 of those 6,000 signals arrive at the same time from the thalamus, that signal can "drive" much of what goes on. Amazing.
This model is important because it gives scientists a new tool for decoding the basic "language" of the brain, which in turn might lead to new ways of understanding and treating a number of neurological and psychiatric disorders.
No comments:
Post a Comment