UNIVERSITY OF CALIFORNIA

DEPARTMENT OF PSYCHOLOGY mi
BERKELEY 4, CALIFORNIA — ~

May 15, 1962

Professor Joshua Lederberg
’ Department of Genetics
Stanford University School of Medicine
Stanford Medical Center
300 Pasteur Drive
Palo Alto, California

Dear Professor Lederberg:

I am pleased that information about our research has reached the other
side of San Francisco Bay by way of Tokyo.

Most of the work mentioned in the "Men and Molecules" program has not Cy
yet been published. J am sending you, therefore, one published article,

three papers in press and a paper that I just presented at the Federation Oh
Meetings.

As you will see from these papers, animals raised under more complex
conditions, when compared with littermates raised in impoverished envi-
ronments, develop greater total activity of cholinesterase throughout
the brain and also develop a greater weight of cerebral cortical tissue.
In some further research that is not yet written up, we have found that
per cent protein and hexokinase activity per unit weight do not differ \.
between the complex environment and restricted environment groups of
animals. Cholinesterase activity, which does not increase in the cortex
as rapidly as does the weight of the cortex, thus acts differently from
both protein and hexokinase. We also have in progress histological
analyses of the brains of these groups of rats.

If you wish further information about this work, I would be happy to
supply it. I would also appreciate any comments or suggestions that you
might wish to make.

Sincerely,

Mark R. Rosenzweig
Professor= 7-7"

 

MRR:HL

Enclosures 5

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