Maternal Behaviour

Re: symposium 822

Michael Numan

On Wed Dec 9, alison Fleming wrote
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>Michael,
>I think trying to understand how the inhibitory circuit intersects with the excitatory circuit is a terrific idea. What I understand from your discussion of the results is that the MeAmyg (possibly dfferent parts) has 2 functions in this context...one inhibitory, responding to novelty, etc..... and the other, excitatory and involved in the execution of mb, as in sniffing, licking, etc..all in response to chemosensor cues, one assumes...but that the vmh is purely inhibitory to the expression of the behavior. Your predictions then would be that with increasing experience with pups the pattern of c-fos expression in meamyg vs vmh would be different-with a decrease in vmh activation across time (as pups become less novel) but perhaps an increase in meAmyg (at least in excitatory portions) across time (as animals become maternal). Is this correct? Also, do you think the vmh normally exerts an inhibition over the mpoa in the virgin animal? By what circuitry, do you know? There's lots to think about. If you are there, let me know. I sent a message earlier that was somehow eliminated!!!

Dear Alison,
I'm in the middle of giving final exams, so this is the first time I have looked at the discussion board.
I think your predictions about fos in MA and VMN are accurate.
It would be interesting to test whether MA lesions would interfere with the preference of maternal postpartum females for pup odors/bedding.
The vmn projects to MPOA: see Canteras et al (1994) JCN, 348, 41-79.
Did you see our Annals NYAS review? Volume 807. You have a presentation in it.
It is possible that the VMN and MPOA are parallel negative and positive circuits, with no need for direct interaction. However, the fact that MPOA projects to VMN and the reverse, suggests that interaction between these structures is important for MB.See my double labeling paper in J Neuroend (1997) for possible importance of MPOA to VMN projections.
Michael

Sat Dec 12