Vestibular stimulation

Kate Jeffery kate at anatomy.ucl.ac.uk
Wed Nov 20 10:55:13 EST 1996


In article <Pine.LNX.3.91.961113231643.25493F-100000 at Hera>, sblack at UBISHOPS.CA (Stephen Black) writes:
> I'm discussing the vestibular system with my undergraduate class in 
> physiological psychology. I wonder if anyone would care to confirm or 
> correct the following:
> 
> I've told them about the Barany (rotating) chair method of stimulating the 
> semi-circular canals. The typical finding is that a blindfolded subject 
> will perceive rotation correctly while being accelerated up to speed, 
> will no longer perceive rotation some time after being rotated at a 
> constant speed, and then will experience a sensation of rotation in the 
> opposite direction (falsely) on braking to a stop.
> 
> However, much research seems to go on these days not in a Barany chair 
> but in a human centrifuge, and there are many natural situations, such as 
> travelling on a curve in a car, in a jet, etc. It seems to me that this 
> type of rotation at the end of a radius is different from the Barany 
> chair type which is around your own axis. I expect that constant rotation 
> in a centrifuge, unlike in a chair, would continue to produce a 
> vestibular sensation of rotation.
> 
> Correct? I haven't seen anyone discuss the distinction between the two 
> types of rotation but it seems to me they must be different. Perhaps it's 
> considered too obvious to mention.
> 
> 
> -Stephen
> 
> ------------------------------------------------------------------------
> Stephen Black, Ph.D.                      tel: (819) 822-9600 ext 2470
> Department of Psychology                  fax: (819) 822-9661
> Bishop's University                    e-mail: sblack at ubishops.ca
> Lennoxville, Quebec               
> J1M 1A9
> Canada
> ------------------------------------------------------------------------
> 

I would have thought that off-centre rotation included components of linear 
acceleration. Maybe some vestibular physiologist could enlighten us as to 
how the different forms are coded? I vaguely think I once knew, but have 
long forgotten. 

As regards fairgound rides, even an ordinary roundabout is pretty good for 
experimenting on. It's really true that it's impossible to tell how fast you 
are rotating when it is reasonably constant, as long as you keep your head 
still, but this is true even when you are being rotated off-centre. And as 
soon as you move, you know exactly how fast you are going round. It's pretty 
nauseating. I did some playing round with this the other day when I took my 
daughter to the playground, because I have been running experiments looking 
at what happens to spatial representation in rats when they are rotated 
below the vestibular threshold. The next thing is to find out what happens 
when they are rotated above it, but I am putting this off because I suspect 
the two types of acceleration make things pretty complicated. It's pretty 
hard to persuade a rat to keep its vestibular apparatus fixed on the centre 
of rotation when it is spinning around! If anyone has any ideas...

Cheers,

kate Jeffery
kate at anatomy.ucl.ac.uk






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