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The Maternal BrainKashmala Qasim

NROC61

Kinsley, C.H & Lambert, K.G. (2006). The maternal brain. Scientific American(January), 72-79.

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Outline

1. Introduction

2. Structural changes & Significancea) Cortex

b) mPOA

c) Hippocampus

3. Hormonal changes: Oxytocin

4. Cellular changes: Glial cells

5. Changes beyond lactation period

6. Summary

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Mothers are made, not born

Hormonal fluctuations

that occur during

pregnancy may modify

the female brain

Increase in size of

neurons

Structural changes

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Structural Changes: CortexDef. receives and processes sensory information & controls voluntary movements

1) Cortex

Cortices of pregnant rats fromimpoverished environments werecomplex = rats from enriched settings

Significance:

- Faster at catching prey

- Food-deprivation studies: virgin rats

took longer to find the cricket and

eat it (270 sec vs. 50 sec).

http://www.familyhopecenter.org/english/images/cortex_indepth_large.jpg

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Structural Changes: mPOADef.

2) mPOA

- cell bodies of the neurons increase in

volume- length and number of dendritesincreases as pregnancy progresses

- neuronal alterations accompany a risein protein synthesis

Significance:

- mPOA neurons direct the mothersattention & motivation to offspring

- Maternal behavioural traits: care,

protection and nurture

V

P

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Structural Changes: HippocampusDef. regulates memory, learning & emotions

3) Hippocampus

- Ebb-and-flow variations inthe CA1 region of thehippocampus

- Increase in dendritic spines asthe females levels of estrogenrise

- - Reduction in neuronal activityin the CA3 region &basolateral amygdala ---

regulate stress and emotion

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Hippocampus

Significance

1) Spatial ability

- Pregnant rats better than age-matched

virgin rats at remembering the location

of food in maze tasks

2) Amygdala: Lessened fear & anxiety

- easier to leave the nest & forage faster

- forced swimming, investigate the space

less likely to freeze up

3) Dendritic Spines: input to associated

neurons, leads to enhanced ability of the

mothers to navigate mazes & captureprey

8-arm radial maze

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HormonalChanges

Oxytocin

- triggers birth contractions andmilk release

- effects on hippocampus:improves memory & learning

- production of long-lastingconnections between neurons in

the hippocampus

- Study: Injections of oxytocininto the brains of virgin femalemice improved their long-termmemory

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3) Cellular Changes

Glial cells

- astrocytes, star-shaped glial

cells that provide nutrientsand structural support forneurons

- significantly more complexand numerous in mPOAneurons & hippocampus,than those in virgin rats

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Changes Beyond Lactation Period

Mother rats up to two years oldequivalent to human females olderthan 60learn spatial tasks significantly faster than age-matchedvirgin rats and exhibit less steep memory declines

At every age tested (six, 12, 18 and 24 months), mothers were betterat remembering the locations of food rewards in mazes

Fewer deposits of amyloid precursor proteinswhich seem to play a

role in the degeneration of the aging nervous systemin two parts ofthe hippocampus, the CA1 region and the dentate gyrus

Mother rats spent more time in the fear-evoking open arms of themaze

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Summary- Structural changes are observed in the

cortex, mPOA neurons and hippocampus

- Changes contribute to increased spatial

ability, foraging ability, maternalbehaviour and able to catch prey faster

- An increase in oxytocin = milk release,

contractions

- Glial cells (astrocytes) increase- These effects remain long after the

lactation period has ended & mitigate

effects of aging