Brain and Behavior - Notes
Chapter 1: What are the Origins of Brain & Behavior?
What is the Brain?
● The brain is an organ → it consists of nervous tissue
○ The cells within the tissue are called nerve cells (neurons and glial cells)
● Half of human brain cells (87 billion) are called neurons and interconnect with each
other and with the muscles and the organs of the body with fiber that can extend
over long distances. The other half (86 billion) are glial cells → they support the
function of the neurons.
○ The neurons send electrical and chemical signals to communicate with each
other → with sensory receptors in the skin, with muscles, and with internal
body organs
○ Most of the connections between the brain and body are made through the
spinal cord, a tube of nervous tissue in our vertebrae → the spinal cord sends
nerve fibers to our muscles and internal body organs and receives fibers from
sensory receptors on many parts of our body
● Together, the brain and the spinal cord make up the central nervous system (CNS)
→ this is the part of our nervous system encased in bone
, ● All the processes that radiate out and beyond the brain and spinal cord, are in the
peripheral nervous system (PNS).
The Human Brain
● The cerebrum is responsible for most of our conscious behaviors.
● It enfolds the brainstem: a set of structures responsible for most of our unconscious
behaviors.
● The second major brainstem structure is the cerebellum, which is specialized for
learning and coordinating our movements.
Locked-in Syndrome
● When Martin Pistorius was 12 years old, his health began to deteriorate. Eventually,
he lapsed into a coma, a condition in which he seemed completely unconscious. His
parents placed Martin in a nursing home, where over a number of years he became
conscious of his condition, although he remained completely paralyzed and unable to
communicate. Martin suffered from locked-in syndrome, a condition in which the
brain is intact, functioning, and sensitive to the external world but with its nerve fiber
pathways that produce movement inactivated.
,What is Behavior?
● Most behaviors consist of a mix of inherited and learned actions
○ Example: sucking reflex in newborns = inherited, but eating later in life =
strongly influenced by learning and culture
● Most behavior is not innate but rather acquired during life and culturally determined
Evolution of the Human Brain
● We don’t descend from chimpanzees, but we do share a common Hominin ancestor
→ the first species that walked upright
● Australopithecus “southern ape” (4 million years ago) → brain of 0.4 kg
● Homo sapiens “knowing man” (120,000 years ago) → brain of 1.48kg
𝑎𝑐𝑡𝑢𝑎𝑙 𝑏𝑟𝑎𝑖𝑛 𝑠𝑖𝑧𝑒
● Encephalization Quotient (EQ) =
𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑏𝑟𝑎𝑖𝑛 𝑠𝑖𝑧𝑒 (𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑡𝑜 𝑏𝑜𝑑𝑦 𝑤𝑒𝑖𝑔ℎ𝑡)
○ Example: a cat has an EQ of 1
○ Homo sapiens → EQ 7.0 (modern humans have the largest brain size relative
to body weight)
● Our brain weight tripled throughout 4 million years
How did our brain get so big?
● Lifestyle adjustments
○ Social group size → humans started hunting in groups and needed bigger
brains for communicating in these groups
○ Eating fruit → it is more difficult to eat fruit than grass, because with fruit you
have determine which fruit you pick
○ Fire → to cook and with that predigest our food → this saves us a lot of time,
so we have more time for social interaction → we need to have a complex
nervous system in order to interact with others → bigger brains
● Efficient brain cooling
○ Circulating blood functions as a radiator in our brain → this enabled high
metabolism
● Neoteny
○ Juvenile features in the adult animal → large head relative to body size
, ○ Adult humans closely resemble the infants of gorillas and chimpanzees
Chapter 2: What is the Nervous System’s Functional Anatomy?
● The brain is a plastic organ; neural tissue has the ability to adapt to the world →
neural plasticity
Brain-Body Orientation
● Illustrates brain structure location from the frame of reference of the human face
● Dorsal → back
● Ventral → belly
● Medial → middle
● Lateral → side
● Anterior → in front of
● Posterior → behind
Spatial Orientation
● Illustrates brain structure location in relation
to other body parts and body orientation
● Rostral → beak
● Caudal → trail
● Superior → above
● Inferior → below
Chapter 1: What are the Origins of Brain & Behavior?
What is the Brain?
● The brain is an organ → it consists of nervous tissue
○ The cells within the tissue are called nerve cells (neurons and glial cells)
● Half of human brain cells (87 billion) are called neurons and interconnect with each
other and with the muscles and the organs of the body with fiber that can extend
over long distances. The other half (86 billion) are glial cells → they support the
function of the neurons.
○ The neurons send electrical and chemical signals to communicate with each
other → with sensory receptors in the skin, with muscles, and with internal
body organs
○ Most of the connections between the brain and body are made through the
spinal cord, a tube of nervous tissue in our vertebrae → the spinal cord sends
nerve fibers to our muscles and internal body organs and receives fibers from
sensory receptors on many parts of our body
● Together, the brain and the spinal cord make up the central nervous system (CNS)
→ this is the part of our nervous system encased in bone
, ● All the processes that radiate out and beyond the brain and spinal cord, are in the
peripheral nervous system (PNS).
The Human Brain
● The cerebrum is responsible for most of our conscious behaviors.
● It enfolds the brainstem: a set of structures responsible for most of our unconscious
behaviors.
● The second major brainstem structure is the cerebellum, which is specialized for
learning and coordinating our movements.
Locked-in Syndrome
● When Martin Pistorius was 12 years old, his health began to deteriorate. Eventually,
he lapsed into a coma, a condition in which he seemed completely unconscious. His
parents placed Martin in a nursing home, where over a number of years he became
conscious of his condition, although he remained completely paralyzed and unable to
communicate. Martin suffered from locked-in syndrome, a condition in which the
brain is intact, functioning, and sensitive to the external world but with its nerve fiber
pathways that produce movement inactivated.
,What is Behavior?
● Most behaviors consist of a mix of inherited and learned actions
○ Example: sucking reflex in newborns = inherited, but eating later in life =
strongly influenced by learning and culture
● Most behavior is not innate but rather acquired during life and culturally determined
Evolution of the Human Brain
● We don’t descend from chimpanzees, but we do share a common Hominin ancestor
→ the first species that walked upright
● Australopithecus “southern ape” (4 million years ago) → brain of 0.4 kg
● Homo sapiens “knowing man” (120,000 years ago) → brain of 1.48kg
𝑎𝑐𝑡𝑢𝑎𝑙 𝑏𝑟𝑎𝑖𝑛 𝑠𝑖𝑧𝑒
● Encephalization Quotient (EQ) =
𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑏𝑟𝑎𝑖𝑛 𝑠𝑖𝑧𝑒 (𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑡𝑜 𝑏𝑜𝑑𝑦 𝑤𝑒𝑖𝑔ℎ𝑡)
○ Example: a cat has an EQ of 1
○ Homo sapiens → EQ 7.0 (modern humans have the largest brain size relative
to body weight)
● Our brain weight tripled throughout 4 million years
How did our brain get so big?
● Lifestyle adjustments
○ Social group size → humans started hunting in groups and needed bigger
brains for communicating in these groups
○ Eating fruit → it is more difficult to eat fruit than grass, because with fruit you
have determine which fruit you pick
○ Fire → to cook and with that predigest our food → this saves us a lot of time,
so we have more time for social interaction → we need to have a complex
nervous system in order to interact with others → bigger brains
● Efficient brain cooling
○ Circulating blood functions as a radiator in our brain → this enabled high
metabolism
● Neoteny
○ Juvenile features in the adult animal → large head relative to body size
, ○ Adult humans closely resemble the infants of gorillas and chimpanzees
Chapter 2: What is the Nervous System’s Functional Anatomy?
● The brain is a plastic organ; neural tissue has the ability to adapt to the world →
neural plasticity
Brain-Body Orientation
● Illustrates brain structure location from the frame of reference of the human face
● Dorsal → back
● Ventral → belly
● Medial → middle
● Lateral → side
● Anterior → in front of
● Posterior → behind
Spatial Orientation
● Illustrates brain structure location in relation
to other body parts and body orientation
● Rostral → beak
● Caudal → trail
● Superior → above
● Inferior → below
