Posted by Estella on August 7, 2006, at 3:49:12
In reply to Re: pain » Estella, posted by Phillipa on August 3, 2006, at 22:52:08
Aaaaaaaaaaaaah.
The Melzack-Wall gate‘The journey begins at the skin, with receptors sometimes called nociceptors that respond with some degree of specificity to a variety of noxious events: mechanical distortion, intensities of heat and cold and chemical changes, for instance. The outputs of these receptors travel brain-ward through at least two very different types of fibres: swiftly through the large myelinated A-fibres, and slowly through the narrow, unmyelinated C-fibres. Both signals arrive at the substantia gelatinosa, the midbrain gateway, where a complicated interaction takes place. A-fibres also send effects inwards via other channels. The A- and C-fibres seem to make two different functional contributions. On the one hand, it seems that the C-fibres are the preponderant transmitters of “slow”, “deep”, “aching”, or “visceral” pains, while A-fibres are implicated in “sharp”, “bright”, “stabbing” pains. Recently Melzack and Wall have suggested a more interesting function for the A-fibres. They act at the substantia gelatinosa to inhibit the effect of the C-fibres, thus closing the gate to pain-impulse transmission, or at least damping the output of that gate. Moreover, the A-fibre channels that bypass the Melzack-Wall gate in the substantia gelatinosa seem to initiate more central activity that sends inhibitory signals back down to the gate, further blocking the transmission of impulses from the C-fibres'.
'Why You Can't Make a Computer that Feels Pain' pp. 199-200 in "Brainstorms: Philosophical Essays on Mind and Psychology"
So...
shart, bright, stabbing pains inhibit slow, deep, aching pains.
I've never heard of 'bright' pain before...
:-)
poster:Estella
thread:672547
URL: http://www.dr-bob.org/babble/social/20060806/msgs/674452.html