Word: thalamus
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Dates: during 2000-2009
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...BRAIN CAN BE TRACKED NOT JUST IN SPACE but also in time. Neuroscientists have long known that consciousness depends on certain frequencies of oscillation in the electroencephalograph (EEG). These brain waves consist of loops of activation between the cortex (the wrinkled surface of the brain) and the thalamus (the cluster of hubs at the center that serve as input-output relay stations). Large, slow, regular waves signal a coma, anesthesia or a dreamless sleep; smaller, faster, spikier ones correspond to being awake and alert. These waves are not like the useless hum from a noisy appliance but may allow consciousness...
...there is no activity anywhere in the brain. In PVS, certain primitive regions of the brain, including the brain stem, which controls autonomic functions such as breathing and the beating of the heart, are still alive. However, the cortex, which is the thinking part of the cerebrum, and/or the thalamus, which connects the brain stem to the cortex, are so badly damaged that they no longer function...
...most difficult thing to understand about a vegetative state is that it allows one to be awake but not aware. (In a coma, you are unresponsive and your eyes are closed.) Because the sleep-wake cycle and certain eye movements are not controlled by the cortex or the thalamus, they can continue without conscious awareness. Even acts of crying and smiling may be reflexive events that do not occur in response to specific stimuli...
...Thalamus The gatekeeper for the senses, this organ focuses your attention by funneling some sensory data deeper into the brain and stopping other signals in their tracks. Meditation reduces the flow of incoming information to a trickle...
...HIGH ROAD Only after the fear response is activated does the conscious mind kick into gear. Some sensory information, rather than traveling directly to the amygdala, takes a more circuitous route, stopping first at the thalamus--the processing hub for sensory cues--and then the cortex--the outer layer of brain cells. The cortex analyzes the raw data streaming in through the senses and decides whether they require a fear response. If they do, the cortex signals the amygdala, and the body stays on alert...