Introduction:
1. Why does the universe exist? & why does consciousness exist?
2. To remember: perception occurs in the brain and not in your skin or the object you see,
brain activity is inseparable from mental activity, it is important to be cautious about what
is or is not an explanation of behavior.
3. Four types of questions about any behavior:
→ physiological: how does the behavior relate to physiology of the brain and other
organs?
→ ontogenetic: how does it develop within the individual?
→ evolutionary: how did the capacity for the behavior evolve?
→ functional: why did the capacity for this behavior evolve? What function does it serve?
4. Many careers relate to biopsychology, including research fields, medical specialties and
counseling and psychotherapy
5. Researchers study animals because the mechanisms are sometimes easier to study in
nonhumans, because they are interested in animal behavior for its own sake, because
they want to understand the evolution of behavior, and because certain kinds of
experiments are difficult or impossible with humans.
6. The nervous system of nonhumans resembles that of humans in many ways
7. Minimalist in animal research allows animal research but it should be held to a minimum
→ Reduction, replacement, and refinement
→ An “abolitionist” wishes to eliminate all animal research regardless of how the animals
are treated or how much value the research might produce.
monism =mental activity and certain types of brain activity are inseparable VS dualism
H1.1 The cells of the Nervous System
The nervous system consists of two kinds of cells; neurons and glia. Neurons receive
information and transmit it to other cells.
Two scientists of the late 1800s and early 1900s are widely recognized as the main founders of
neuroscience—Charles Sherrington (Chapter 2), and the Spanish investigator Santiago Ramón
y Cajal (1852–1934). Cajal’s early education did not progress smoothly. At one point, he was
imprisoned in a solitary cell, limited to one meal a day, and taken out daily for public floggings—
at the age of 10—for the crime of not paying attention during his Latin class.
Cajal wanted to become an artist, but his father insisted that he study medicine as a safer way
to make a living. He managed to combine the two fields, becoming an outstanding anatomical
researcher and illustrator. His detailed drawings of the nervous system are still considered
definitive today.
,The Italian investigator Camillo Golgi found a way to stain nerve cells with silver salts. This
method, which completely stains some cells without affecting others at all, enabled researchers
to examine the structure of a single cell. Cajal used Golgi’s methods but applied them to infant
brains, in which the cells are smaller and therefore easier to examine on a single slide. Cajal’s
research demonstrated that nerve cells remain separate instead of merging into one another.
Some ribosomes float freely within the cell, but others are attached to the endoplasmic
reticulum, a network of thin tubes that transport newly synthesized proteins to other locations.
,Many vertebrate axons are covered with an insulating material called a myelin sheath with
interruptions known as nodes of Ranvier. Invertebrate axons do not have myelin sheaths.
Although a neuron can have many dendrites, it can have only one axon, but the axon may have
branches. The end of each branch has a swelling, called a presynaptic terminal. At that point
the axon releases chemicals that cross through the junction between that neuron and another
cell. The longest axons occur in the longest animals.
An afferent axon (sensorisch) brings information into a structure (admit); an efferent axon
(motorisch) carries information away from a structure (exit). Within the nervous system, a given
neuron is an efferent from one structure and an afferent to another.
If a cell’s dendrites and axon are entirely contained within a single structure, the cell is an
interneuron or intrinsic neuron (short axon) of that structure. For example, an intrinsic neuron of
the thalamus has its axon and all its dendrites within the thalamus.
The widely branching dendrites of the Purkinje cell in the cerebellum (see Figure 1.8a) enable it
to receive input from up to 200,000 other neurons. By contrast, bipolar neurons in the retina
(see Figure 1.8d) have only short branches, and some receive input from as few as two other
cells.
, Glia outnumber neurons in the cerebral cortex, but neurons outnumber glia in several other
brain areas, especially the cerebellum. Overall, the numbers are almost equal.
The brain has several types of glia.
- The star-shaped astrocytes wrap around the synapses of functionally related axons.
→ shields neurons from chemicals circulating in the surrounding.
→ by taking up the ions and transmitters released by axons and then releasing them
back, an astrocyte helps synchronize closely related neurons, enabling their axons to
send messages in waves. Astrocytes are therefore important for generating rhythms,
such as your rhythm of breathing.
→ Astrocytes dilate the blood vessels to bring more nutrients into brain areas that have
heightened activity
→ According to a popular hypothesis known as the tripartite synapse, the tip of an axon
releases chemicals that cause the neighboring astrocyte to release chemicals of its own,
thus magnifying or modifying the message to the next neuron
- microglia act as part of the immune system, removing viruses and fungi from the brain
→ proliferate after brain damage, removing dead or damaged neurons
→ contribute to learning by removing the weakest synapses
- Oligodendrocytes in the brain and spinal cord and Schwann cells in the periphery of the
body:
→ build the myelin sheaths that surround and insulate certain vertebrate axons.
→ supply an axon with nutrients necessary for proper functioning
- Radial glia guide the migration of neurons and their axons and dendrites during
embryonic development
→ When embryological development finishes, most radial glia differentiate into neurons,
and a smaller number differentiate into astrocytes and oligodendrocytes.
