'deficient gain' of sinusoidal smooth pursuit eye movements

[ouzhantekin]

Hey guys,

I don't want to draw you into deep technical stuff however I came across with a sentence where I saw this "deficient gain" thingy in it. Here's the sentence for you to refer:

"...Seventeen patients with acute, mainly unilateral cerebellar infarctions and an intact gain of the smooth pursuit system were compared with 11 patients with cerebellar lesions and deficient gain of sinusoidal smooth pursuit eye movements by means of lesion-mapping imaging..."

What I want to know is that does this "gain" here mean to obtain something? Are the smooth pursuit eye movements something that can be gained from somewhere or something or even somebody? If yes, does the adjective "deficient" here mean that the gaining process is somewhat inadequte so there we have a problem?

I hope I could ask my question clearly. I just need to understand the way the so-called familiar words are used in a medical context to use the insight in my further ventures

source of the sentence: http://www.ncbi.nlm.nih.gov/pubmed/19567703

 

[ouzhantekin]

I just found that "gain" also means "to increase" or "increase" as a noun. Is it correct? So can I paraphrase that part of the sentence as " deficient/inadequate increase" of sinusoidal smooth pursuit eye movements..."?

 

[Tatti Bella]

Yes gain means to increase as well. Not just to achieve something.

I would say that the gains in sinusoidal smooth pursuit eye movements weren't enough. There were small gains but not enough to make a big difference. Does that make sense?

 

[PaulQ]

I would suspect that the word gain is probably being used in a very specialised sense, possibly related to gain = Electronics. An increase in power, voltage, or current, expressed as the ratio of the increased quantity to the original quantity or (more commonly) as the logarithm of this. (OED)

Having read the article and some background1, and as 'smooth pursuit', can be either reflex only or controlled, I suspect that 'gain' ~= comparative control or effective functioning and that deficient gain = comparative lack of control or ineffective functioning.

1 http://en.wikipedia.org/wiki/Smooth_pursuit / http://en.wikipedia.org/wiki/Nystagmus

However, if there's anyone out there with medical knowledge...

 

[ouzhantekin]

So there is a some extent of control or gain to conduct a specific thing but since it is not enough, the action is not properly performed, which brings us the so-called deficit. Am I on the right track?

 

[PaulQ]

Not really, I wish I had not mentioned electronics - it is more the idea of the ratio of the healthy movement and the impaired movement hence the "comparative".

But I do suspect this is a technical use - the smooth-pursuit seems to operate to a maximum of 30 degrees per second, so an intact gain might be 30 degrees per second, whereas deficient gainmight mean a far slower speed or some [comparative] level of inability to employ smooth pursuit.

 

[suzi br]

Does it work properly if you read gain as regain in the sense of being restored
? I am not able to follow the whole thing well enough to check it properly.

 

[papakapp]

So there is a some extent of control or gain to conduct a specific thing but since it is not enough, the action is not properly performed, which brings us the so-called deficit. Am I on the right track?

Correct. "defficient gain" can mean insufficient increase both according to any dictionary I am aware of and also according to common usage.

 

[PaulQ]

It's not a misprint.

Clinical Neurophysiology of the Vestibular System by By Robert W. Baloh, M.D., Kevin A. Kerber, gives a good example of the idea of gain in smooth pursuit at page 186.

The slope of the eye target velocity relationship (in this cases, 0.95) represents the gain of the smooth pursuit system. The mean gain determined from similar plots in 25 normal young subjects was 0.95 +/- 0.07. …
Also smooth pursuit gain decreases with both increasing frequency and increasing velocity of the target.

The gain therefore appears to be the ratio of the speed of the eye and speed of the target. (Cf gain in electronics)

deficient gain will therefore be when the ratio is lower than normal.

 

[ouzhantekin]

Look how I started the topic: "I don't want to draw you into deep technical stuff however..."

And how we ended up

I guess I have the gist of it even though I can't say I got it perfectly.. Thanks a lot for all of your replies ..

 

[wandle]

deficient gain will therefore be when the ratio is lower than normal.

Purely as a matter of English meaning, this tells us that 'deficient gain' means 'a lower gain than would normally be expected'.

 

[ouzhantekin]

Duly noted