Summary Brain
Chapter 1
Why study brain and behavior?
1.
How the brain produces behavio
r is a major unanswered question.
2.
The brain is the most complex or
gan and is found in many group
s of animals.
3.
A
growing list of behavioral disorders can be
explained and treated as the under...
6/21/23, 9:44 AM Summary an introduction to Brain&behavior
Summary Brain
Chapter 1
Why study brain and behavior?
1. How the brain produces behavior is a major unanswered question.
2. The brain is the most complex organ and is found in many groups of animals.
3. A growing list of behavioral disorders can be explained and treated as the understanding of the
brain increases.
Spinal cord = part of the CNS encased by the backbone, provides most of the connections between
the brain and the rest of the body.
Central Nervous System = brain + spinal cord
Peripheral Nervous System = all of the neurons outside the CNS, provides sensory- and motor
connections to and from the CNS (motor to body muscles, sensory & motor to internal body
organs and gut).
Neuron = specialized nerve cell engaged in information processing (behavior).
Parts of the brain:
- The hemispheres (together form the cerebrum)
- Cerebrum responsible for most of our conscious behaviors
- Brainstem responsible for most of our unconscious behaviors
- Cerebellum specialized for learning and coordinating movements (assists the cerebrum)
Embodied behavior (Prinz): proposes that the movements we make and the movements we perceive
in others are central to our behavior. We understand others by not only listening, but also by observing
gestures and other body language.
Main broad approaches (of the causes) of behavior:
1. Mentalism (Aristotle)
A person’s psyche (mind) is responsible for life, as it produces all human intellectual
functions. The psyche was responsible for human consciousness, perceptions & emotions and
certain processes. The brain existed to cool the blood.
2. Dualism (Descartes)
The mind instructed the pineal body (the brain’s center), which lies beside ventricles (fluid-
filled brain cavities), to direct fluid from them through nerves and into muscles. When the
fluid expanded the muscles, the body would move.
Dualism = the idea that behavior is controlled by two entities (mind & body). The theory of
dualism had a mind-body problem (= difficulty of explaining how a nonmaterial mind and a
material body interact). To test this theory turing test.
3. Materialism (Darwin)
= behavior can be explained as a function of the nervous system without recourse to the mind.
Darwin believed that all organisms are related to each other in a way.
Natural selection = Darwin’s theory for explaining how new species (= a group of organisms
that can breed among themselves) evolve and how existing species change over time.
Individual organisms can vary extensively in their phenotype (= characteristics that can be
seen/measured). Members of a species that have the same genotype, are likely to express
similar phenotypic traits. Environment participates in expression of traits epigenetics (= the
study of differences in gene expression related to environment and experience). Epigenetics do
not change genes but influence how genes are expressed.
Important implications:
o Because all animal species are related, their brains must be related.
o Because all animal species are related, their behavior must be related.
o Brain and behavior in complex organisms evolved from simpler organisms’ brains &
behaviors and also depend on learning.
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Hebb’s theory: learning is enabled by neurons forming new connection with one another in the brain.
The resulting neuronal network is a cell assembly (these can interact linking of memories (=
consciousness)).
This is eliminative materialism: if behavior can be described adequately without recourse to the mind,
then the mental explanation should be eliminated.
MCS = minimally conscious state
PVS = persistent vegetative state
Deep Brain Stimulation = neurosurgery in which electrode implanted in the brain stimulate a targeted
area with a low-voltage electrical current to facilitate behavior.
Evolution of nervous systems:
Neurons & muscles Nerve net (jellyfish) Bilateral symmetry (organs on both sides of body are
mirror images) Segmentation (division of similar parts) Ganglia (sort of brain) Spinal cord
Brain.
Chordates = animals that have a CNS.
Cladogram = chart that displays groups of related organisms as branches on a tree.
Primates = eyes positioned at the front, use highly developed visual sense to guide their hand
movements. Humans are most closely related to the Chimpanzee.
Hominids = primates that walk upright. One of the hominid ancestors of human kind is the
Australopithecus.
First human: Homo Habilis (handy man, 2 million years ago) Homo Erectus (upright human, 1.6
million years ago) Homo Sapiens (modern humans, 200.000 years ago), they lived together with
the Neanderthals.
Ways of estimating relative brain size:
1. Estimating relative Brain-Body size
Harry Jerison: as body size increases, brain size increases at about 2/3 the increase in body
weight. Species exhibiting more complex behaviors must possess more brain than species
whose behaviors are fewer and less complex. He developed the Encephalization Quotient: an
average animal had an EQ of 1.
2. Counting brain cells
Karina Foncesa-Azevedo: a counting machine for neurons with which not only the number of
cells in a (part of the) brain can be calculated, but also the brain cells’ packing density. EQ
provides a good comparison of brain size.
Hypotheses for reasoning why the hominid brain enlarged:
1. Climate and The Evolving Hominid Brain
Climate changes have led to physical changes in hominids. Evidence suggests that each new
hominid species appeared after climate changes devastated old environments and lead to new
ones.
2. The Primate Lifestyle
Robin Dunbar: group size is correlated with brain size.
Katharine Milton: hominids that spend more time and effort on foraging, have more brain
cells. Cooking food is a unique contribution to hominid brain development.
3. Changes in Hominid Physiology
Stedman: smaller masticatory muscles paved the way for smaller, more delicate bones in the
head more access to energy-rich food more brain cells.
Dean Falk: if the brain’s radiator (circulating blood) adapted into a more effective cooling
system, brain size could increase. Homo skulls contain holes through which cranial blood
vessels pass.
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4. Altered Maturation
Heterochrony: study of processes that regulate the onset and end of life stages and their
developmental speed and duration.
Neoteny: juvenile stages of predecessors become adult features of descendants. This has led to
adults with proportionally larger bodies and larger skulls to house larger brains.
When dealing with human brain size comparisons think of:
- Brain measurement; brain size can change (plasticity)
- Correlating brain size and intelligence
- What intelligence is; species typical-behavior = behavior displayed by all members of a
species. Requirements depend on looking for difference between species or within species.
Culture = learned behaviors passed from generation to generation through teaching and experience.
Memes = elements/styles that spread from person to person within a culture.
Chapter 2
Neuroplasticity = the nervous system’s potential for physical/chemical change to adapt to
environmental change and to compensate for injury.
Phenotypic plasticity = an individual’s capacity to develop into more than one phenotype
(neuroplasticity is part of this).
Anatomical organization: Functional organization:
Afferent = incoming to CNS
Efferent = outgoing from CNS
The three layers that protect the brain are the dura mater, the arachnoid layer & the pia mater. Together
they from the meninges. Between the arachnoid layer and the pia mater flows cerebrospinal fluid
(CSF). This cushions the brain so that it can move/expand slightly without pressing on the skull.
The anterior-, middle-, and posterior cerebral arteries send blood to the cerebrum.
Stroke = the sudden appearance of neurological symptoms as a result of severely interrupted blood
flow.
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Glossary of Anatomical Location and Orientation
Term Meaning with respect to the nervous system
Anterior Near/toward the front of the animal/head
Caudal Near/toward the tail of the animal
Coronal Cut vertically from the crown of the head down
Dorsal On/toward the back of a four-legged animal
Frontal Of the front
Horizonta Cut along the horizon
l
Inferior Below
Lateral Toward the side of the body/brain
Medial Toward the middle (the body’s midline)
Posterior Near/toward the animal’s tail (spinal cord at the back for humans)
Rostral Toward the beak (front) of the animal
Sagittal Cut lengthways from front to back of the skull to reveal a medial view into the brain
Superior Above
Ventral On/toward the belly of a four-legged animal
Lobes (all part of the cerebral cortex) of the brain:
- Temporal lobe: hearing, language and musical abilities
Lies below the lateral fissure, beneath the temporal bone at the side
of the skull
- Frontal lobe: executive functions, such as decision making
Lies anterior to the central sulcus and beneath the frontal bone of the
skull
- Parietal lobe: directs movements toward a goal or to perform a task
(grasping an object)
Lies posterior to the central sulcus and beneath the parietal bone at the top of the skull
- Occipital lobe: visual processing
Lies at the back of the brain and beneath the occipital bone.
Macro view
Grey matter = areas of the nervous system composed predominantly of cell bodies and capillary
blood vessels that either collect and modify information or support this activity.
White matter = areas of the nervous system rich in fat-sheathed neural axons that form the
connections between brain cells.
Ventricles = two wing-shaped cavities that contain CSF. It is thought that they play an important role
in maintaining brain metabolism.
Corpus callosum = band of white matter containing about 200 million nerve fibers that connects the
two hemispheres to provide a route for direct communication between them.
Micro view
The brain has two main type of cells; neurons, that carry out the brain’s major functions, and glial
cells, that aid and modulate the neuron’s activities. Neurons are connected to each other via axons
(nerve/tract).
Nuclei = a group of cells forming a cluster that can be identified with special stains to form a
functional grouping.
Nerve = large collection of axons coursing together outside the CNS.
Tract = large collection of axons coursing together inside the CNS.
Most behaviors are the product of many interacting brain areas and levels. Each region adds a different
dimension to the behavior. This hierarchical organization affects virtually every human behavior.
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