Scientists Find Differences in Mammalian Male and Female Brains

Scientists have found
difference in mammalian males and females based on a study done in mice. There
are some cells unique to male brain and some unique to female brain. These
sex-specific cells were found in a regioin of the brain that governs both aggression
and mating behaviours.
The findings were reported in
the online version of the journal Cell recently and David Anderson of Howard
Hughes Medical Institute involved in the study said that there are differences
between male and femala mammalian brains at the level of cellular composition
as well as gene expression but those differences are subtle, and their
functional significance remains to be explained.
There are many different types
of cells within the brain, such as neurons that transmit signals and glial
cells that support neural functions. Although all of these cells contain the
same set of genes, or genome, the types of cells differ in how they express
those genes. As an analogy, one can imagine the genome as an 88-key piano in
each cell. Each cell does not use all 88 keys. Therefore, the subset of keys
that the cell "plays" determines the type of cell it is.
The hypothalamus is a
fundamental region of the brain found in all vertebrates including humans.
Previous studies have shown that a specific anatomic subdivision in the
hypothalamus, called the ventrolateral subdivision of the ventromedial
hypothalamus (VMHvl), contains cells that control aggression and mating
behaviors. In these studies, strong stimulation of these neurons in male and female
mice immediately caused the animals to become aggressive, even in the absence
of any threat. However, weak stimulation caused the mice to begin mating
behaviors.
It was known that different
genes are expressed in the two mouse sexes—indeed, a genetic test can tell you
whether a mouse is male or female—but this is the first discovery of types of
cells that are sex-specific in a mammalian brain. Cells are considered to be
distinct types when the expression of large clusters of genes varies from cell
to cell.
Future work will try to determine the functions of these
differing cell types.
Source : Caltech
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