Core of the Central Assembly Located!!!

Do anything you can to get a copy of the Science Times (Section E) of the New York Times for Tuesday 24 March 1998. Sandra Blakeslee's article at the bottom left of the front page discusses the observation that as people age their ability to estimate time deteriorates. Young people asked to say when three minutes has elapsed can do so within a few-second margin of error, while those in the range of 60-70 will be off an average of 40 seconds in that same three minutes span. "Duke University neuroscientist Warren Meck and a graduate student, Matthew Matell, have now proposed a model of this clock based on studies of brain anatomy."

I'd place a URL for the article in this message were I able to locate the article on the Web, but since I can't find it, I'll try to quote the sections that so excite me.

Referencing the great number of time-sensitive events that must be analyzed and handled simultaneously by a basketball player, Blakeslee notes: "In the case of the basketball player, different parts of the brain are working on different tasks. Cells in the visual system are looking for places to run or pass the ball. Cells in the motor system are controlling movements. Cells in the auditory system are listening for information from teammates on what to do next. Each of these specialized cell circuits carrying out different jobs tend to oscillate or fire at different rates. some might be firing 5 times a second, others up to 40 times a second. It is as if they are operating independently on different time scales, yet the basketball player's brain must integrate them so that he or she can decide what to do with the ball.

"For this task of coordination, Dr. Meck and his assistant have nominated a structure in the midbrain called the striatum, which is loaded with spiny neurons, so called because their projections are thick with spines. Such neurons are well connected in that each one---and there are thousands of them---is linked to tens of thousands of other cells via dentrites coming from other parts of the brain. The dendrites are the slender spines that help brain cells communicate. They detect oscillations or cell firing rates that occur all over the brain, Dr. Meck said, 'and the question has been what the heck do they do with them.'

" 'We think spiny neurons integrate these signals,' Dr. Meck said, and, based on previous experience of what is important, selet those that are beating at the same frequency and synchronize them. This collective timing signal is sent to higher cortical areas where, in a grand loop from the brain's basal ganglia to its frontal lobes, perceptions and actions are coordinated and acted upon. When a person is performing several tasks at once and needs to measure time, spiny neurons parcel out the tasks, Dr. Meck said."

The article goes on to discuss the role of dopamine in the function of the striatal time function, and presents a bit more evidence that this area is responsible for detection of intervals of small duration.

It seems logical to me that such an area might well be the nucleus Tomkins postulated as the analyzer circuit for stimulus increase, stimulus decrease, stimulus level---the three conditions responsible for the six basic innate affects. Even shame-humiliation might be sensed as an alteration in the rate of stimulus increase or stimulus decrease during either of the positive affects. All we need to cement our case would be the demonstration of a connection between this striatal nucleus and the bulbofacial fibers I suspect as the nerve trunks that carry messages from the affect system to the muscles of the face.

I'll try to get a message through to the scientists mentioned in the article as soon as possible and give you followup as it occurs. I do so wish Silvan were alive to read about this development.

• Corpus Striatum to Brainstem by Don Nathanson, 4/4/98