MadSci Network: General Biology

Re: Does metabolic rate affect perception of time?

Date: Sun Feb 13 22:05:49 2005
Posted By: Alex Goddard, Grad student, Neuroscience, Harvard Medical School
Area of science: General Biology
ID: 1105222224.Gb

Hi Jonathon -

     That's an interesting question. Ultimately, I don't think the basal metabolism directs the "speed" of perception of time per se. For a fly, I think the perception of time is more a function of a its anatomy. However, I think the two issues are connected by one concept: flies are small.

     Obviously, flies are orders of magnitude smaller than people. And it's been shown that smaller animals have faster metabolic rates than larger ones. But there's something more to this issue than just size. A fly's nervous system is orders of magnitude less complex than a human's as well. Less processing of visual input means that the fly visual system can do its job a lot faster than its human counterpart, and thus the fly can perceive more 'time units' than a person. Even at the level of the retina, a fly can react to light between 10-100 times faster than other animals. Therefore, fly-time is 'faster' than human-time.

     As far as people are concerned, I haven't been able to find much data indicating that changes in heart rate cause much of a change in cognitive abilities. One study found that a drug that decreases heart rate has no change on cogntive ability (at least the by the tests they were giving). With respect to basal metabolic rate changes, they are not necessarily related either. For instance, when a person has a fever, their basal metabolic rate increases; but I'm sure you can appreciate that in that state, your cognitive abilities are pretty impaired!

     An important point to bring up is that basal metabolic rate is not the same as your heart rate. Your metabolic rate is a measure of how much energy you expend to do all your bodily functions (i.e breathe, think, walk around, lift your arms, etc). While heart rate and metabolic rate are related, they don't necessarily correlate.

     I hope that answers your question!

-Alex G

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