Re: THC & Cognitive Function

Anders Sandberg (
10 Dec 1999 12:13:50 +0100

"Zeb Haradon" <> writes:

> It's well known that the neural pathways for recognizing objects are
> different from those used in recognizing faces. This is illustrated by
> various disorders in which a person can recognize common household objects,
> but cannot recognize his father's face, or the opposite disorder where he
> can recognize faces but not objects.

The face recognition pathways are part of the general ventral object recognition stream; recognition of everyday objects is based on data from the lower levels of the stream just like face recognition. Interestingly, tools and other objects closely associated with actions seem to be independently recognised from the other objects (likely with strong links to frontal areas), since they are associated with various action-memories.

                                              -> normal objects
low level visual processing -> higher levels --> faces (with limbic input) 
                                              -> tools (with frontal input)

> I suggest a line of research to discover if the receptor which THC
> binds to is responsible for mediation of facial recognition, and
> possibly usage of THC for treatment of facial aphasia (I don't know
> if that's the proper term for it).

Prosopagnosia. My guess is that THC affects the limbic system, and this is the soruce of the over-detection of faces. Since most people with prosopagnosia have damaged inferotemporal cortex, THC might not help them much since the actual recognition system is out of order, the increase in modulation won't change anything. Then again, they might feel happier.

> It's been
> discovered recently that there are THC receptors in the eyes (which is why
> marijuana helps glaucoma patients), I'd bet that the receptors go all the
> way down the facial visual system.

There are cannabinoid receptors in a lot of places, the effects are complicated. In the hippocampus it seems to mediate memory loss for example (antagonists have nootropic effects).

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y