Physio Chapter 1 Notes
Historical Highlights in Biological Psychology
• Hippocrates: the brain was also the source of intelligence.
• Aristotle: heart was the source of intellect
• Herophilus, who is often referred to as the father of anatomy, believed that
the ventricles (the fluid-filled cavities in the brain) played this important
• Galen believed that the ventricles played an important role in transmitting
messages to and from the brain.
◦ Fluids flowing within the ventricles were believed to be continuous with
fluids in the nerves. This notion of the nervous system as a network of
fluid-filled, interconnected tubes and chambers persisted until nearly
• Descartes: Mind-body dualism: the bodies of both humans and animals
◦ However, Descartes believed that human beings had unique capacities
that they did not share with other animals and that these were contained
in the mind.
◦ the mind is neither physical nor accessible to study through the physical
• In contrast, the modern neurosciences, including biological psychology, are
based on monism: proposes that the mind is the result of activity in the
brain, which can be studied scientifically.
• With a better understanding of electricity, thanks to observers such as
Benjamin Franklin, the Galen-Descartes notion of control via the movement
of fluids was finally discarded.
• Charles Bell & Francois Magendie: Transmission of information along nerves
is typically a one-way street
◦ Sensation and movement have their own designated routes
• Franz Joseph Gall: Phrenology
◦ Used busts to identify traits located under different parts of the skull.
◦ Bumps on the skull were believed to indicate that the underlying trait
had been “exercised.”
◦ Although Gall’s system was an example of very bad science, the
underlying principle that functions could be localized in the brain turned
out to be valuable
• Paul Broca: correlated the damage he observed in patients with their
behavior and concluded that language functions were localized in the brain
Histology: • Histology refers to the study of microscopic structures and tissues.
◦ Histological methods provide means for observing the structure,
organization, and connections of individual cells.
• Tissue to be studied under the microscope must be prepared for viewing in
a series of steps:
◦ Tissue must be made thin enough to allow light to pass through it.
▪ Brain tissue is fragile and somewhat watery, which makes the
production of thin enough slices impossible without further treatment.
▪ To solve this problem, the first step in the histological process is to
“fix” the tissue, either by freezing it or by treating it with formalin, a
liquid containing the gas formaldehyde
▪ Formalin not only hardens the tissue, making it possible to produce
thin slices, but it also preserves the tissue from breakdown by
enzymes or bacteria.
◦ Once tissue is fixed, it is sliced by a special machine known as a
◦ Researchers select particular stains depending on the features they wish
▪ nerve tissue would appear nearly transparent under the microscope if
it were not for a variety of specialized stains
▪ Golgi silver stain: analysis of a small number of single cells
▪ Nissle stain: identifying clusters of cell bodies, the major bulk of the
nerve cell, within a sample of tissue
▪ Myelin stain: allow you to follow pathways carrying information from
one part of the brain to another by staining the insulating material
that covers many nerve fibers
▪ horseradish peroxidase: If you know where a pathway ends but
would like to discover its point of origin
• When this enzyme is injected into the end of a nerve fiber, it
travels backward toward the cell body
◦ Once tissue is appropriately prepared, it can be viewed under either a
light or electron microscope
• Computerized tomography (CT):
◦ provides excellent structural information
◦ However, a CT scan cannot distinguish between a living brain and a dead
one. In other words, the CT scan provides no information regarding
activity levels in the brain.
▪ This limits the usefulness of CT in helping us answer questions about
• Positron emission tomography, or PET:
◦ allows researchers to observe brain activity
◦ programmers have assigned red and yellow to areas of high activity and
green, blue, and black to areas of low activity • Magnetic resonance imaging, or MRI:
◦ uses powerful magnets to align hydrogen atoms within a magnetic field
◦ Next, radio frequency (RF) pulses are directed at the part of the body to
be imaged, producing “resonance,” or spinning, of the hydrogen atoms.
◦ When the RF pulses cease, the hydrogen atoms return to their natural
alignment within the magnetic field. As the atoms “relax,” eac