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Janet Paterson, your post on the brain's stopwatch is interesting. I repeat part of it here: "Meck described the location of the timer -- in the dead center of the brain -- Sunday at the annual meeting of the American Association for the Advancement of Science. He and colleagues used magnetic resonance imaging to study the activity of the brain. They asked volunteers to squeeze a ball every 11 seconds. Then they watched what happened inside their heads. The scans revealed that the striatum, a structure deep inside the brain, was working hard during this exercise. In this, as with many other things, human brains work a lot like rats'. Meck's earlier research showed that rats trained to press a lever for food after a specified time used the same part of their brains. More confirmation of the relevance of this for humans comes from separate studies by Dr. John Gibbon of Columbia University. He looked at the ability of people with Parkinson's disease to keep track of time. Gibbons found that when Parkinson's patients are off dopamine replacement therapy, they have trouble measuring short intervals. Their disease results from damage to the same part of the brain where Meck believes he has located the interval clock. The discovery of the interval clock has no practical uses for now. However, it may help scientist someday craft better treatments for Parkinson's patients and others who suffer damage in this part of the brain." I will be bold or brazen enough to object to the analogy chosen. "Interval Clock" implies a process dedicated component of the brain performing this function (which is usually physically accomplished via mechanical escapement devices or counters of constant rate phenomena). The alternative analogy label, short-term memory, may be a better classification. This term is often cited as the explanation of Alzheimer's disease (AD). The chaotic fiber connections in most of the brain seems the major physical damage in AD. Short term cognition lack may be comprised of inability to maintain conscious attentiveness and storing these immediate past (ongoing) sense organs inputs. This may be due to the random neural connections. In the normal brain, the storing of sensory inputs is selective via capacity of the brain, habits of learned non-conscious and conscious (cognitive concentration or focusing) et cetera characteristics. There may be ability to monitor the amount of such pulses or heartbeats or ?? to estimate the passage of time when the rat focuses on feeding after learning that the pellets appear at regular intervals. The AD brain may not be focus-able. The Parkinsonian brain may not be able to focus or concentrate cognition fully or at full speed (normal events but limited in frequency of signals because of insufficient dopamine). Squeezing a ball every 11 seconds involves two functions at minimum. The counting to eleven being the most likely for the human; but, not likely for the rat which is probably not cognitively, consciously able to perform such abstract mentation. The squeezing of the ball involves the decision to do so and then the actual sequences of neural and muscle and feedback et cetera processes. I note slowness in mentation, lessened ability to concentrate or focus when the levodopa is less than sufficient - as many have reported. Recalling words, names, thinking in general requires the neural network messages. Whether one can learn to use alternative chemicals or alternative neural circuits re-trained to do the functions of networks having insufficient dopamine are not well studied yet. As we are able to obtain the basic information and the hypotheses and etiological processes become more accurately and precisely elaborated, more progress will occur in learning to help our selves and all the species perhaps. Sorry if all this is not of interest to you. ron 1936, dz PD 1984 Ronald F. Vetter <[log in to unmask]> http://www1.ridgecrest.ca.us/~rfvetter/