The Limbic System:
The Limbic System is the part of the brain responsible for controlling emotions, motivation, and
memory. The main structures involved in the limbic system include the amygdala, the
hippocampus, and the hypothalamus.
Dopamine is an important neurotransmitter in the brain that has been connected to regulation of
movement and emotion. We chose to focus on how dopamine is carried throughout the brain in
order to help to better understand how the brain processes abstract thoughts and emotions.
Dopamine follows four different pathways including the Mesolimbic, and Mesocorital pathways,
which regulate emotions. In the mesolimbic and mesocorital pathways the dopamine originates in
the Ventral tegmental, and ends in the nucleus accumbens or in the frontal cortex of the brain.
Steps-Dopamine Cell Signaling










Action potential stimulates dopaminergic cells
Tyrosine is modified by the enzyme Tyrosine hydroxylase to form DOPA. DOPA decarboxylase
Vesicles containing dopamine travel into presynaptic terminal
Calcium ions enter the presynaptic terminal and releases the dopamine form the vesicles, through the
Synaptic cleft.
Dopamine then attaches the D1 receptor
Within the cell membrane the G Protein is
then activated, which activates the adenylyl
cyclase.
The Adenylyl cyclase converts ATP into
cAMP, which is the second messenger.
The cAMP then activates Protein kinase A,
and is transferred to the Mitogen activated
protein kinase cascade.
The Early gene “c-fos” then identifies the
activated neuron.
The neurotransmitter then separates from
the D1 receptor, and is transported back into
the presynaptic cleft, and taken through
dopamine re-uptake pumps.
Results in rewards, motivation, pleasure.
Recent Discoveries
Thorough studies cocaine and other CNS stimulant drugs have proven their ability to increase the
release of dopamine, and then effectively block reuptake of dopamine at the presynaptic membrane.
Cocaine specifically binds to dopamine re-uptake pumps and blocks their ability to remove the
dopamine from the synaptic cleft. This keeps the dopamine levels high and causes continuous nerve
stimulation. Because of the sudden overload of available dopamine, the cell cuts back the amount of
dopamine receptors available. When the effects of the cocaine wear off, more dopamine is required to
create the same effect it had before due to the decrease in the dopamine receptors.
Abstract Thoughts and Emotions
1
Abstract Thoughts and Emotions
2
Works Cited
“Dopamine Functions." THE MEDICAL NEWS | from News-Medical.Net - Latest Medical
News and Research from Around the World. Web. 9 Dec. 2012.
<http://www.news-medical.net/health/Dopamine-Functions.aspx>.
Audience. "How does cocaine produce its effects? | National Institute on Drug Abuse."
National Institute on Drug Abuse. Web. 9 Dec. 2012.
<http://www.drugabuse.gov/publications/research-reports/cocaine-abuseaddiction/how-does-cocaine-produce-its-effects>.
"Does the difference between physically active and couch potato lie in the dopamine
system?." International Journal of Biological Sciences. Web. 9 Dec. 2012.
<http://www.biolsci.org/v06p0133.htm#b36>.
MacLean, Paul, "it is the mother of invention, and the father of. "Limbic System: The
Center of Emotions ." The Healing Center On-Line. Web. 9 Dec. 2012.
<http://www.healing-arts.org/n-r-limbic.htm>.
"Neuron Synapse « Anthropology.net." Anthropology.net. Web. 9 Dec. 2012.
<http://anthropology.net/2008/01/20/dopamine-transporter-gene-and-primatesocial-behavior/neuron-synapse/>.
"THE BRAIN FROM TOP TO BOTTOM." Le cerveau àtous les niveaux. Web. 9
Dec. 2012.
<http://thebrain.mcgill.ca/flash/a/a_03/a_03_cl/a_03_cl_que/a_03_cl_que.html>.
MLA formatting by BibMe.org.
Abstract Thoughts and Emotions
3
Abstract Thoughts and Emotions
4