1. Interpersonal Relationships
Megan Grove
2/10/13
“Best Experiment Ever!”
“VTA Plasticity and Drug-Induced Contextual Learning”
Part One; The Study
This study explores the idea that isolation and “deficits in social life, especially
during adolescence” can cause a lasting effect on the brain, and the way it develops
addiction behavior. Effects of unmet social needs on “anxiety, aggression, cognitive
rigidity, and spatial learning” have all been well researched, but the learning and
subconscious process behind addiction “remains elusive.”
An experimental group of rats were kept individually isolated during postnatal
days 21-42, which corresponds to mid-adolescence in humans, and then exposed to
varying levels of alcohol and amphetamine. Their results were compared to the
control group of rats, which were housed in groups.
What was observed was that the period of isolation enhanced the “long-term
potentiation of NMDA receptor-mediated glutamatergic transmission in the VTA.”
Even with re-socialization and integration back into the colony of rats, the changes to
the experimental group (susceptibility to addiction, preference for drug-receiving
environment, difficult behavior extinction) could not be reversed. They formed
addictions much more easily than the control rats, “showing preference“ for the small
box used to deliver the drugs after just one exposure, as opposed to the control group,
which only became conditioned after repeated exposures. Also, when given the same
amphetamine “extinction protocols,” it took longer for the experimental group to

2. Interpersonal Relationships
Megan Grove
2/10/13
“kick the addiction,” instead preferring the environment where they had received
reward for long after the reward stopped being available.
This data suggests that, “early life deficits in social experience increase
addiction vulnerability.” The researchers believe that the brain reacted to the lacking
social environment, in which the opportunity for any reward (dopamine) had been
diminished, by increasing its sensitivity to any conditioning that involves rewards
(dopamine release), thus “over interpret[ing]” any reward it receives.
Part Two; The Meaning
The findings of this study support the importance of meaning, as described in
Elliot, Kao, & Grant’s 2004 “Mattering.” If we do not get appropriate amounts of
genuine social interaction (positive or negative), we are impacted in a number of
ways. Our immune systems are compromised; we experience higher levels of stress,
and depression.
There have been small case studies observing how the development of
language suffers when the brain is deprived of human contact and socialization. Now
we see evidence that, if social needs are not met, especially during crucial
developmental stages, the dopamine neurons and neural systems of our brain may
develop to make us more easily manipulated, and vulnerable to addiction-behaviors.
If social isolation can cause rats to become significantly more prone to developing
addiction through elevated dopamine sensitivity, perhaps varying levels of social

3. Interpersonal Relationships
Megan Grove
2/10/13
success through adolescence could contribute to individual variance of addiction
susceptibility.
According to the addiction vulnerability study, “when you drink or take
addictive drugs, that triggers the release of dopamine.” Morikawa and Whitaker go on
to explain that in the experimental group, dopamine neurons became especially eager
to respond quickly and intensely to input. Since this reinforces itself, the neurons
continue learning to respond more quickly to the context in which they were
rewarded, establishing dopamine as not only a NT associated with reward, but also
with learning and memory. “The Biology of Love, Lust and Attachment” by Fisher,
Thompson in 2007 compares love to addiction based on animal studies of cocaine
addiction, which also indicate activity of the dopamine pathways and reward centers
in the brain.
The Ventral Tegmental Area (VTA) is defined as being a central part of the
“reward system” of the brain, where dopamine producing and distributing cells are
located. Activity in this area is associated with the perception of positive emotion,
arousal and the motivation to seek and acquire rewards. The study also says that
elevated dopamine levels are associated with mood swings, emotional dependence,
intense energy, and ecstasy – the kinds of things someone might experience with
drugs, or when falling in love.
The addiction vulnerability study suggests that the “deprived brain reacts to
the impoverished environment” by becoming more sensitive to rewards-based
conditioning, without discrimination. That means drugs, and alcohol, but also things

4. Interpersonal Relationships
Megan Grove
2/10/13
like food and love, that stimulate the dopamine pathways to reinforce “environmental,
behavioral and psychological cues,” as well. According to Morikawa, the importance
of observing the rats environmental preference for the box used to deliver the drugs
provides a more useful, constructive way to think about addiction, rather than
thinking of it only as the desire for more of what made the subject feel good. We could
use these observations to make inferences about why people behave the way they do
when faced with situations or substances that elevate dopamine levels.
Part Three; The Implications
If the findings of the addiction vulnerability study can be generalized, like
Morikawa suggests, it is easy to see all the inferences we could make from the data
regarding the subconscious mental processes behind our actions. People could
become “more conditionable to not only drugs,” but anything stimulating the rewards
pathways of the brain to be interpreted as a reward.
Food –contributing to the weight problem developing in our country, to the
earlier onset of diabetes and a host of other over-eating complications.
Attention – positive or negative, possibly explaining the willingness to act out
inappropriately for the reward of mattering; or explaining abnormalities in behavior
such as histrionic personality disorder.
Exercise – physical activity also stimulates the release of dopamine, so this
research could explain over-exercising behavior in eating disorder patients.

5. Interpersonal Relationships
Megan Grove
2/10/13
Another inference, such as we discussed in lecture, this could be a determining
factor of whether an individual develops “addiction” to love, and why it doesn’t
happen all the time, to everyone. Romantic love stimulates the VTA, prompting the
release of dopamine, and if those neurons were super-sensitive to it, the rewards
would be exaggerated and easily over-interpreted by the brain. Letting go would also
become more difficult, and take much longer. The loss of dopamine stimulation in the
brain that is very sensitive to it must feel terrible, and could also explain why, in the
aftermath of a failed romantic relationship, some individuals turn to maladaptive
behavioral patterns, such as drugs, alcoholism, and overeating for comfort.
If complete social isolation during youth can create enduring effects on the
dopaminergic pathways in the brain, it seems possible that these changes could also
be observed on a scale. For example, partial isolation, or isolation among peers but
not at home, isolation except for the Internet, which may or may not contribute
worthwhile human interactions, could all create slightly different variations of the
same effect, accounting for some of the variations in behavior and motivation
between individuals. Thinking about adolescence, high school, and the classic cliché
subtypes, generalizing this study to real life makes sense.
This research could change the way we think about addiction. Not just drug
addiction, but the way our brains become conditioned to rewards. Dopamine might
not be the only involved NT, and there may be dozens of other contributing factors,
but it is one good, plausible answer as to why addiction develops and what the
individual differences could be.

6. Interpersonal Relationships
Megan Grove
2/10/13
Citations
1A) University of Texas at Austin (2013, January 23)
“Socially isolated rats are more vulnerable to addiction, report researchers.”
Science Daily. From http://www.sciencedaily.com/releases/2013/01/130123165040.htm
1B) Leslie R. Whitaker, Mickael Degoulet, Hitoshi Morikawa.Social Deprivation Enhances VTA
Synaptic Plasticity and Drug-Induced Contextual Learning. Neuron, 2013; 77 (2):335
2) Fisher, H. & Thomson Jr, J.A. (2007)
“Lust, romance, attachment: Do the side effects of serotonin-enhancing
antidepressants jeopardize romantic love, marriage and fertility?”
In Platek, S (Ed.) Evolutionary Cognitive Neuroscience (pp.246-270) MIT Press.
3) Mattering: empirical validation of a social- psychological concept.
Elliott, Gregory C.; Kao, Suzanne; Grant, Ann-Marie
Self and Identity, Vol 3(4), Oct-Dec 2004, 339-354.