1
Chapter 1 - What are the origins of brain and
Behavior?
1.1 21st century - Why study brain and behavior links?
1. How does the brain produce behavior? → improvements in world
2. Brain is complex - function and evolution
3. Increasing understanding of the brain helps explain behavioral disorders
What is the brain?
- ½ neurons, ½ glial cells (support neuron function)
- Spinal cord - communication between brain and body
- CNS = brain and spinal cord; encased in bone, core structure mediating behavior
- PNS = rest of processes
Cerebrum → conscious behavior
Brain stem → unconscious behavior
Cerebellum → learning, coordinating
movement; conjoint evolution with
cerebrum
Embodied behavior:
- Research and philosophical
argument
- Movements we make and
movements we perceive are central to
behavior → brain can’t be separated
from body (PNS), it needs stimulation
- Heron 1957 - effects of sensory deprivation → it is highly disturbing (for ex locked-in
syndrome = can sense but can move)
- AI - can a computer be conscious in the absence of embodied behavior? (Harvey)
What is Behavior
- Behavior = “patterns in time”
- Animals → inherited behavior (can be performed with no previous experience, “built in”
the brain; brain is preorganized but modifiable through experience)
- Cultural learning = parents teach to offspring
- Smaller brains more dependent on heredity
- More complex NS ⇒ more complex behavior, more dependent on learning
, 2
1.2 Perspectives on Brain and Behavior
- Mentalism = philosophical position that mind is responsible for behavior (dates back to
aristotle)
- Descartes - mechanical principles for behavior, but also a nonmaterial mind ⇒ dualism
- ⇒ mind-body problem = how do the body and nonmaterial mind interact
- Darwin - materialism = the workings of brain and nervous system explain behavior
- Mendel - inheritance principles
- Epigenetic influences can be long lasting - experience can deeply influence brain
- Animals are all related → brains are similar, so our understanding of the
brain can expand through animal studies
- Animals are related → behavior is related - Darwin’s “The expression of
emotions in man and animals) → heritable traits
- Brains evolved to be increasingly complex, from species to species
- Hebb: learning is neabled by small groups of neurons forming new connections with one
another to form a cell assembly, which is the substrate for a memory; assemblies
interact, connect with each other, linking memories → complex behavior, consciousness
- Materialistic argument
- Materialism may be seen as reductionist, denying religion, whereas it is actually
neutral
1.3 - Evolution of brains and Behavior
- Can be studied using the brains of other species
- Brains and brain cells evolved relatively recently
- Taxonomy: kingdom, phylum, class, order, family, genus, species
- Only animal kingdom has muscles and nervous systems (which co-evolved to
produce the behavior of movement)
- Evolution of nervous system:
- 1. Neuron and muscles - enabling movement
- 2. Nerve net - present in evolutionarily older phyla, no structure, only connections
between sensory and motor neurons
- 3. Bilateral symmetry - NS is more organized
- 4. Segmentation - muscular segments correspond to nervous segments; present
in spinal cord and brain: repeating NS segments
- 5. Ganglia = clusters of neurons, primitive brains (command centers); in some
phyla (for ex insects), encephalization (ganglia in the head) happens
- 6. Spinal cord - in chordates (Brain + Spinal cord) connects the brain with
sensory receptors and muscles
- 7. Brain = greatest degree of encephalization; the brains of chordates share
similarities but also distinctive specializations specific to the species
- Chordate Nervous System
, 3
- Increasing size and complexity of brain is to accommodate new behaviors
(movement, improved learning, social behaviors)
- Folding and size increase in mammals (folding to fit more brain and surface area
into smaller recipient
1.4 Evolution of Human Brain and Behavior
Humans: Members of Primate Order
- Monkeys, apes; great vision is used to guide very precise movements → use of tools
- Primates have long gestation periods and long childhoods
- Primates have larger brains, higher intelligence
- Apes (humans and others) have flexible shoulders that free the arms (for climbing trees)
- Hominids = primates that walk upright; there used to be lots of species of hominids
coexisting, but we are the only remaining one.
Australopitecus = hominid ancestor; walked up right, but had smaller brain than us, used tools
and retained the ability to climb trees
The First Humans
- Homo erectus (standing
upright; had a large brain, like
homo sapiens, which is probly why
he migrated and survived for 2 mil
years
- Note homo florensis was
around up to 13 000 years ago - it
is recent that homo sapiens is the
only species left
- Neanderthals in europe
interbred with homo sapiens until
they died out (they had culture,
tools, music, religion, rites and
language)
- No particular reason for
why humans are so prevalent
other than large brain; mixing with
neanderthals made them more
physically resilient
Brain size and behavior
, 4
- Brain size is the only brain measure available through fossils
- Encephalization quotient (EQ)
- = actual brain size/expected brain size (relative to body weight)
- Brain size vs. brain size to body weight
- Australopithecus → EQ 2.5
- Homo sapiens → EQ 7.0
- Brain weight tripled
- Causes:
- Climate change causes environmental pressures
- Lifestyle adjustments (social groups → more communication, eating fruit is more difficult,
use of fire (cooking → more caloric gain) → more time for social interaction
- Efficient brain cooling - circulating blood like a radiator, enabled the brain to maintain
high metabolism → physiological changes
- Neoteny - retention of juvenile features in adult animal (humans resemble baby gorillaz);
dogs are neotenic wolves; heterochrony = processes that regulate the onset and
end-of-life stages and their developmental speed and duration; neotenic process in
humans - learning
- Prolonged gestation and childhood
- However, among humans it is the number of connections between brain cells that
matters
- Location of number of cells:
more cells in cerebrum → more
complex behavior, more cognitive
versatility; more cells in cerebellum →
more motor functions - topographic
maps for diff functional areas
- Connections: in small brains,
neurons with diff functions are spread
out evenly (mostly sensory and motor
functions); bigger brains - neurons
aggregate by function to reduce
distance, and new functions for more tasks require new regions and new connections;
connectome maps represent connections through which each of these regions influence
each other
Acquisition of Culture
- = learned behaviors passed from generation to generation through teaching and
experience
- Cultural elements = memes (ideas behaviors, styles that spread from person to person
- Indiv diff in brain structure → dev of specific memes → further selective pressure in brain
dev
Chapter 1 - What are the origins of brain and
Behavior?
1.1 21st century - Why study brain and behavior links?
1. How does the brain produce behavior? → improvements in world
2. Brain is complex - function and evolution
3. Increasing understanding of the brain helps explain behavioral disorders
What is the brain?
- ½ neurons, ½ glial cells (support neuron function)
- Spinal cord - communication between brain and body
- CNS = brain and spinal cord; encased in bone, core structure mediating behavior
- PNS = rest of processes
Cerebrum → conscious behavior
Brain stem → unconscious behavior
Cerebellum → learning, coordinating
movement; conjoint evolution with
cerebrum
Embodied behavior:
- Research and philosophical
argument
- Movements we make and
movements we perceive are central to
behavior → brain can’t be separated
from body (PNS), it needs stimulation
- Heron 1957 - effects of sensory deprivation → it is highly disturbing (for ex locked-in
syndrome = can sense but can move)
- AI - can a computer be conscious in the absence of embodied behavior? (Harvey)
What is Behavior
- Behavior = “patterns in time”
- Animals → inherited behavior (can be performed with no previous experience, “built in”
the brain; brain is preorganized but modifiable through experience)
- Cultural learning = parents teach to offspring
- Smaller brains more dependent on heredity
- More complex NS ⇒ more complex behavior, more dependent on learning
, 2
1.2 Perspectives on Brain and Behavior
- Mentalism = philosophical position that mind is responsible for behavior (dates back to
aristotle)
- Descartes - mechanical principles for behavior, but also a nonmaterial mind ⇒ dualism
- ⇒ mind-body problem = how do the body and nonmaterial mind interact
- Darwin - materialism = the workings of brain and nervous system explain behavior
- Mendel - inheritance principles
- Epigenetic influences can be long lasting - experience can deeply influence brain
- Animals are all related → brains are similar, so our understanding of the
brain can expand through animal studies
- Animals are related → behavior is related - Darwin’s “The expression of
emotions in man and animals) → heritable traits
- Brains evolved to be increasingly complex, from species to species
- Hebb: learning is neabled by small groups of neurons forming new connections with one
another to form a cell assembly, which is the substrate for a memory; assemblies
interact, connect with each other, linking memories → complex behavior, consciousness
- Materialistic argument
- Materialism may be seen as reductionist, denying religion, whereas it is actually
neutral
1.3 - Evolution of brains and Behavior
- Can be studied using the brains of other species
- Brains and brain cells evolved relatively recently
- Taxonomy: kingdom, phylum, class, order, family, genus, species
- Only animal kingdom has muscles and nervous systems (which co-evolved to
produce the behavior of movement)
- Evolution of nervous system:
- 1. Neuron and muscles - enabling movement
- 2. Nerve net - present in evolutionarily older phyla, no structure, only connections
between sensory and motor neurons
- 3. Bilateral symmetry - NS is more organized
- 4. Segmentation - muscular segments correspond to nervous segments; present
in spinal cord and brain: repeating NS segments
- 5. Ganglia = clusters of neurons, primitive brains (command centers); in some
phyla (for ex insects), encephalization (ganglia in the head) happens
- 6. Spinal cord - in chordates (Brain + Spinal cord) connects the brain with
sensory receptors and muscles
- 7. Brain = greatest degree of encephalization; the brains of chordates share
similarities but also distinctive specializations specific to the species
- Chordate Nervous System
, 3
- Increasing size and complexity of brain is to accommodate new behaviors
(movement, improved learning, social behaviors)
- Folding and size increase in mammals (folding to fit more brain and surface area
into smaller recipient
1.4 Evolution of Human Brain and Behavior
Humans: Members of Primate Order
- Monkeys, apes; great vision is used to guide very precise movements → use of tools
- Primates have long gestation periods and long childhoods
- Primates have larger brains, higher intelligence
- Apes (humans and others) have flexible shoulders that free the arms (for climbing trees)
- Hominids = primates that walk upright; there used to be lots of species of hominids
coexisting, but we are the only remaining one.
Australopitecus = hominid ancestor; walked up right, but had smaller brain than us, used tools
and retained the ability to climb trees
The First Humans
- Homo erectus (standing
upright; had a large brain, like
homo sapiens, which is probly why
he migrated and survived for 2 mil
years
- Note homo florensis was
around up to 13 000 years ago - it
is recent that homo sapiens is the
only species left
- Neanderthals in europe
interbred with homo sapiens until
they died out (they had culture,
tools, music, religion, rites and
language)
- No particular reason for
why humans are so prevalent
other than large brain; mixing with
neanderthals made them more
physically resilient
Brain size and behavior
, 4
- Brain size is the only brain measure available through fossils
- Encephalization quotient (EQ)
- = actual brain size/expected brain size (relative to body weight)
- Brain size vs. brain size to body weight
- Australopithecus → EQ 2.5
- Homo sapiens → EQ 7.0
- Brain weight tripled
- Causes:
- Climate change causes environmental pressures
- Lifestyle adjustments (social groups → more communication, eating fruit is more difficult,
use of fire (cooking → more caloric gain) → more time for social interaction
- Efficient brain cooling - circulating blood like a radiator, enabled the brain to maintain
high metabolism → physiological changes
- Neoteny - retention of juvenile features in adult animal (humans resemble baby gorillaz);
dogs are neotenic wolves; heterochrony = processes that regulate the onset and
end-of-life stages and their developmental speed and duration; neotenic process in
humans - learning
- Prolonged gestation and childhood
- However, among humans it is the number of connections between brain cells that
matters
- Location of number of cells:
more cells in cerebrum → more
complex behavior, more cognitive
versatility; more cells in cerebellum →
more motor functions - topographic
maps for diff functional areas
- Connections: in small brains,
neurons with diff functions are spread
out evenly (mostly sensory and motor
functions); bigger brains - neurons
aggregate by function to reduce
distance, and new functions for more tasks require new regions and new connections;
connectome maps represent connections through which each of these regions influence
each other
Acquisition of Culture
- = learned behaviors passed from generation to generation through teaching and
experience
- Cultural elements = memes (ideas behaviors, styles that spread from person to person
- Indiv diff in brain structure → dev of specific memes → further selective pressure in brain
dev
