Biopsychology is the branch of psychology that focuses on the relationship between the brain and behavior. The document traces the history of biopsychology from ancient Greek theories of Plato and Aristotle to modern imaging technologies like EEG, CAT scans, and MRIs. Key developments included Galen's ventricle theory, Descartes' dualism and pineal gland theory, Golgi's staining technique that allowed visualization of neurons, and Berger's invention of the EEG. Modern biopsychology uses structural imaging to study the brain's structure and function and further the understanding of behavioral disorders.

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BIOPSYCHOLOGY
Biopsychology
Schalonia Smith
University of Phoenix
August 25, 2008

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Biopsychology
Biopsychology is the branch of psychology that focuses on the brain and behavior.
Biopsychologists attempt to explain behavior from biological perspective, concentrating on the
brain’s relationship and affect on behavior. From ancient Greece to modern times, the brain’s
influence and relationship to behavior has fascinated the human race. The following will discuss
the history, theories, assumptions, and technologies of biopsychology.
The History of Biopsychology
Despite human autopsies being illegal during their time, ancient Greeks were among the
first to recognize the brain’s affect on behavior. Plato theorized the brain as an “…organ of
reasoning…” (Wickens, p. 4). Plato’s pupil, Aristotle, believed the heart was the organ of reason
and the brain simply cooled the blood (Wickens, 2005). Greeks relied on animal autopsies during
ancient times since human bodies could not be examined (Wickens, 2005). These animal
autopsies gave ancient Greeks a general ideal of the shape of the brain and its ventricles
(Wickens, 2005).
Galen Theory
Galen was “one of the first writers to propose a theory of brain function based on the
ventricles…” (Wickens, p. 4). Galen, like previous Greek theorists, was unable to autopsy the
human body and relied on animal dissections (Wickens, 2005). This lack of actual visual
knowledge of the human brain led to Galen’s misguided theories on the workings of the
ventricles, heart, and brain. “Galen believed that the heart was the crucial organ of the body
because it contained the vital spirit that gave the spark of life to the person” (Wickens, p. 4).
According to Galen, the vital spirit provided substance to the brain and was transferred to a large

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group of blood vessels located at the base of the brain (Wickens, 2005). Galen named this large
group of blood vessels rete mirabile, which translates to wonderful net (Wickens, 2005).
Although Galen knew of the existence of four ventricles, the purposes of the four
ventricles were not defined until Nemesius did so in the fourth century AD (Wickens, 2005).
Nemesius’s hypothesis that the lateral ventricles contained sensory and mental impressions,
reason was controlled by the third ventricle, and memory was contained in the fourth ventricle
was not disproved until 1500 years later (Wickens, 2005). At the same time Nemesius’s
hypothesis was disproved, Galen’s theory of rete mirabile was also disproved (Wickens, 2005).
Rene Descartes
Credited for changing the way the brain is studied, Rene Descartes contributed too many
areas of psychology, including the area now known as biopsychology. As a dualist, Descartes
believed the mind and body are separate entities. According to dualism theories, the mind is
immaterial and non-physical, operating separately from the physical, material body. To explain
how an immaterial mind can control a physical body, Descartes theorized the pineal glad as the
communication point of mind and body. As the pineal gland is located next to the third ventricle,
partially covered in cerebrospinal fluid, and a single structure in an otherwise paired structure
brain, Descartes viewed the pineal glad as the ideal “meeting” spot for mind and body (Wickens,
2005).
Rene Descartes also theorized about behaviors that require no mental intervention
(Wickens, 2005). To explain his concept of automatic reflex, Descartes theorized that vital spirit,
contained in the hollow tube of a sensory nerve, relayed a message to the brain’s ventricles
(Wickens, 2005). According to Descartes, the message was then relayed from the brain’s
ventricles to animal spirit that in turn moved muscles in the appropriate way (Wickens, 2005).

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Though most of Descartes’ theories have since been disproved, Descartes opened the door to
new thinking and experimenting related to the brain’s function and relationship to behavior.
Luigi Galvani
Luigi Galvani is most famous for his experiment in which he used electricity to cause a
severed frog leg to convulse (Wickens, 2005). Galvani’s research on amputated animal parts,
mainly frog legs, led him to conclude that Descartes’ “animal spirits” were electrical in nature
(Wickens, 2005). Galvani’s theories shifted the belief that nerves worked on a hydraulic system
to an electrical system (Wickens, 2005).
Camillo Golgi
With the invention of the microscope in 1665 embarked biopsychology on yet another
shift in beliefs. Before Camillo Golgi’s accidental discovery of silver nitrates affect on nerve
cells, scientists relied on ineffective means for studying nerve cells (even with the invention of
the microscope). “Golgi’s technique only stained around 2 percent of the cells in any given slice
of nervous tissue” (Wickens, p. 8). By highlighting only 2 percent of the cells neurons and their
many components became more visible (Wickens, 2005). This new visibility allowed Santiago
Ramon y Cajel to describe almost every part of the brain’s neuro structure (Wickens, 2005).
Cajel’s discoveries lead to the underlying assumption in biopsychology that the brain is a
complex, organized, predictable structure rather than a big jumble of nerves as previously
believed (Wickens, 2005). Golgi’s straining method also lead to Cajel’s discovery that nerves are
separate, individual structures, which never actually touch (Wickens, 2005).
Modern Biopsychology
Modern biopsychology has advanced considerably in the past century, largely due to the
advancement of technology in the past century. Just as the invention of the microscope created a

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new understanding of nerves, the invention of computerized imaging machines has enlightened
biopsychologists to the functions of various areas of the brain. Even before computerized
imaging machines, macroelectrode techniques were being used to advance psychological (and
biological) understanding of the brain (Morris and Maisto, 2002).
One macroelectrode technique invented in 1929, the electroencephalograph (EEG), is still
used today. The EEG, developed by Hans Berger, allows researchers to “hear” the electrical
activity of the brain (Morris and Maisto, 2002).
Flat electrodes, taped to the scalp, are linked by wires to a device that translates electrical
activity into lines on a moving roll of paper (or, more recently, images on a computer
screen). The shape and pattern of these waves vary depending on what you happen to be
doing at the time. (Morris and Maisto, p. 70).
Due to technological advances, biopsychologists can now view the actual structure of a
live brain through structural imaging (Morris and Maisto, 2002). Two modern structural
imagining devices are the computerized axial tomography (CAT) and the magnetic resonance
imagining (MRI) devices (Morris and Maisto, 2002). The CAT device utilizes x-ray technology
to photograph the entire head from top to bottom (Morris and Maisto, 2002). The resulting
images are than combined by a computer to form a three-dimensional image of the brain (Morris
and Maisto, 2002). The MRI machine surrounds the head with a magnetic field and exposes the
brain to radio waves (Morris and Maisto, 2002). The exposure to radio waves causes energy to
be released from hydrogen atoms in the brain (Morris and Maisto, 2002). “The energy released
by different structures in the brain generates an image that appears on a computer screen. Recent
advances in MRI technology now enable scientists to compare precise three-dimensional images
obtained over extended periods” (Morris and Maisto, p. 70). This new development in MRI

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technology has enabled psychologist to track neurodegenerative disorders such as Alzheimer and
Huntington (Morris and Maisto, 2002).
Conclusion
Philosophers and psychologists alike have often debated the mind body question.
Biopsychology is directly related to this debate. As it progresses, biopsychology lends new
evidence to support the brain’s relationship with behavior and the body. Rene Descartes dualist
approach to biopsychology has long been and underlying principle in biopsychology. With the
discovery of new technologies, biopsychology has advanced the knowledge of how the brain
works, affects behaviors, and interacts within itself. This new knowledge has lead to an
understanding of many behavioral disorders, which in turn has lead to treatments and even cures
for psychological disorders.

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References
Wickens, A. (2005). Foundations of Biopsychology (2nd ed.). England: Pearson.
Morris, C. G., & Maisto, A. A. (2002). Psychology: An Introduction (12th ed.). Upper Saddle
River, NJ: Prentice Hall.