August 12, 2011

Behavioral Inhibition System - What it means


Chorpita et al. (1998)

I've recently summarized the role of the septo-hippocampal system of Gray & McNaughton's (2000) theory (see here).  After thinking about "why" I like the theory, I decided to write another post, not just on G & M theory, but also on the state of neuroscience in general.

One thing that strikes me as odd is that a lot of people tend to only focus on a certain brain area or set of local connections in review articles or just chit-chat with a colleague... which is fine and may be the point of the review/conversation!

The story of Gray and McNaughton (2000), as because there has been some recent posts on the subject, goes beyond this and (tries) to explain a wide range of observed phenomena, ranging from anxiety, fear, OCD, depression, memory (amnesia comes to mind in addition to spatial fields, which they do not deny), etc, and set all these into a hierarchical system. 


[I think initially (first edition of the theory appeared in 1982) the theory got a bad (or not a brilliant) reputation, because a lot of it tended to focus on behavioral approaches and did not include enough cognition.  So, the theory was revised in which it included recent data that came out and tended to focus more of itself on cognition.  I digress.]

Not only do they try to explain these through the use of a more basic mechanism, but they go through this and give support for their model from a range of levels.... neurochemical (aminergic signalling), cell firing in clusters and locking together (theta rhythm), neuroanatomical connectivity (within hippocampus and extra-hippocampal areas), behavioral observations, cognitive performance, etc...But what I really like is that they jump into the clinical realm, asking how their theory may apply to a more clinical setting. This, I think, is a hallmark of a good theory, when it can be applied and make a good effort at trying to explain seemingly disparate data and trying to unify these data with a common mechanism. After all, isn't science always after that simple, elegant theory (physics comes to mind with the enigmatic search for their Grand Unified Theory (GUT)).


What I enjoy most about Gray and McNaughton's theory is that it not only serves as a "conflict detection" system ("resolution" occurs elsewhere), which is a small fraction of the totality of the theory, but they realize and encompass a wide range of brain area.  The septo-hippocampal system connects with several anatomical that are extra-hippocampal and this gives rise to the behavioral inhibition and behavioral arousal systems and, indeed, the "conflict/resolution system".  This then manifests itself in such phenomena that we can observe and measure clinically.

As far as spatial memory and the hippocampus is concerned, the BIS theory is only trying to explain data that is presented to it. I think it does a fairly good and convincing job... time will tell whether it's right/wrong/or some combination (this is probably the case, as it is with almost every theory set forth).  The theory does not deny that there is probably a memorial component to the hippocampus (McNaughton, 1997), and, indeed, it even advocates for such a cognitive component! If you look at it in isolation of "just the hippocampus" you can see it from one angle, and if you look at it through a distributed-system view, interacting with prefrontal areas, accumbens, retrosplenial, cingulate, amygdala etc etc... you can see a different view and interpretation of the data. This whole "goal" (behavioral /cognitive "goal", many if not all are unconscious) thing is really just confusing the matter if one is trying to look at spatial memory in isolation and from the view of a specific brain area or look at with the view as it being a distributed function.... I tend to think that most functions cannot be localize to certain areas but rather are a dynamic and interactive sets of functions that are distributed all throughout the brain... Just a thought, but, most cognitive processes I do not think can be isolated to specific regions but their neuronal algorithms that help "put it in motion" might be...

If you're trying to study "X", it's hard not to consider how "Y", "Z" downstream are affected, and how "V" and "W" are influencing the process(es/ing) of "X"... the realm of fMRI comes to mind for this particular example. 



Refs:

Chorpita, B. F., & Barlow, D. H. (1998). The development of anxiety: the role of control in the early environment. [Review]. Psychol Bull, 124(1), 3-21. 

Gray, J. A. & McNaughton, N. (2000) (2nd ed.). The neuropsychology of anxiety: an enquiry into the functions of the septo-hippocampal system.  Oxford Psychology Series.  Oxford University Press, USA; 2nd edition.

McNaughton, N. (1997). Cognitive dysfunction resulting from hippocampal hyperactivity--a possible cause of anxiety disorder? Pharmacol Biochem Behav, 56(4), 603-611. 

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