Thursday, July 5, 2007

200 Hertz

James Brown's song "I feel good" keeps popping into my head and I got a funny urge to get up from my chair and start dancing. I am feeling very good indeed. I just did a search on Google for "hippocampus high-frequency" and I found exactly what I was looking for. I found strong evidence to support my theory regarding the purpose of the oscillations in the hippocampus. My hypothesis (see my last article) is that the brain's memory system (the hippocampus) needs two types of reference signals as follows:
  • The first reference signal is variable and is synchronized to the low-frequencies generated by sequences within the hippocampus; it is used primarily for sequence learning. There is one reference signal of this type per sequence.
  • The second reference signal has a much higher frequency than the first and is fixed. It is used to record the relative intervals between signals within a sequence. One such signal can serve a huge number of sequences.

It turns out that in-vitro and in-vivo experiments on rats brains reveal three types of oscillations in the hippocampus: theta (4–10 Hz), gamma (20–80 Hz) and high-frequency (~200 Hz). Personally, I think that both theta and gamma oscillations should just be categorized as low-frequency oscillations. This would give us two distinct types of oscillations: low-frequency and high-frequency. I suspect that theta frequencies are generated mostly in connection with visual signals whereas gamma frequencies are associated with auditory signals.

It is almost 1-AM where I am right now (Texas). I just thought I would post this before I go to sleep. Later.