Saturday, October 9, 2010

Neuroscience of Falling in Love

Again a re-post.
An old post, but very informative in tabulating the "neural representations".NGF is something which affects the neural plasticity and this also explains why humans become "crazy" when in love.

"Researchers think that falling in love is a basic emotion like anxiety or fear. When falling in love the same brain structures as in anxiety are stimulated: the amygdala and related circuits and neurotransmitters. Human beings are anxious until the bond with the loved one is accomplished. Anxiety is than replaced by positive feelings of stability and pleasure. The euphoria and focused attention when falling in love is explained by involvement of the reward and motivation systems in the human brain.


The neurochemical and hormonal basis of falling in love:

Reduced functionality of the serotonin transporter
Cortisol levels are significantly higher amongst those subjects who have recently fallen in love, this suggests the stressful and arousing condition associated with falling in love
FSH and testosterone levels are lower in men in love, while women of the same group presented higher testosterone levels. The opposite directions of the testosterone levels in men and women have not yet been clarified
Nerve growth factor, one of the key regulators of synaptic plasticity and neural survival during development and at adulthood and also increasingly recognized as potential mediator of anxiety, emotions and behavioral modifications, is significantly elevated compared to subjects with long lasting relationship and with subjects without a relationship. There was also a significant positive correlation between levels of NGF and the intensity of romantic love as assessed with the passionate love scale
Other regulators of synaptic plasticity and neural survival during development and at adulthood and also increasingly recognized as potential mediator of anxiety, emotions and behavioral modifications such as neurotrophins 3 and 4 and brain derived neurotrophic factor were not significantly diferent from those in love and subjects with a long lasting relationship and subjects being alone
In conclusion the neurobiological substrate of falling in love not only involves activation of the hypothalamic pituitary adrenal (HPA) axis and increase of cortisol levels. Also central neuropeptides such as vasopressine and oxytocin may play a role in the regulation of the HPA axis when falling in love. Since recent peripheral levels of neurotrophins have been investigated when falling in love but only the nerve growth factor is significantly elevated. This last factor is also connected with cortisol and the other central neuropeptides. The authors of this last research speculate that:

NGF could play a role in the molecular mechanisms of human romantic love by acting as a fine modulator of distinct endocrine functions. Alternatively, another possibility to explain our results may be that NGF plasma concentrations in subjects in love would be raised secondarily in a stress-dependent manner.

All the hormone and neuropeptide concentrations mentioned in the list are reversible in the sense that these hormones and neuropeptides revers to normal levels.

This finding would suggest that the hormonal changes which we observed are reversible, state-dependent and probably related to some physical and/or psychological features typically associated with falling in love."

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