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The Biology of the Mind
Chapter 2
Central Principle to Psychology
Everything Psychological is
Simultaneously
BIOLOGICAL
Historical Elements of Biology in
Psychology
Phrenology – Theorist Franz Gall (early 1800’s)
claimed bumps on the skull could reveal our
mental abilities and our character traits.
 Through observations of people, Gall pinpointed
areas of the brain responsible for 37 traits.
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– Ex. Gall observed that people with strong sexual
drives had well developed neck and skulls bases.
– Believed “amativeness” (inclination towards love or
sexual arousal) was localized in the cerebellum.
Phrenology
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What we learned from
Phrenology:
– The idea that various
regions of the brain
have particular
functions.
Linking Biology to Psychology
Because we are biopsychosocial human
beings, it is important to study how
biology effects our behavior.
 Body’s information system handling all
tasks is handles by NEURONS – billions of
interconnected nerve cells.
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– Sensory neurons
– Motor neurons
– Interneurons
The Neuron
Parts of a Neuron
Dendrites: Receive messages from other
cells
 Cell Body: The cell’s life support center
 Axon: Passes messages from the cell body
to other neurons
 Terminal Branches: form junctions with
other neurons

How do Neurons Transmit Info?
Neurons transmit messages when
stimulated by signals from our senses or
when triggered by chemical signals from
neighboring neurons.
 Fires an impulse called the action potential
– a brief electrical charge that travels
down the axon.
 Branches out to other neurons

How do Neurons Communicate?
Neural impulses travel down the neural pathway
to the synapse –meeting point between
neurons.
 Synapses are actual gaps between neurons that
are bridged by neurotransmitters –chemical
messengers
 Neurotransmitters cross the synaptic gaps at
1/10,000th of a second binding the neurons
briefly to send information.
 Then the process of reuptake occurs – the
sending neuron reabsorbs the excess
neurotransmitters.

Neurons
Neurotransmission
and the reuptake
process
How Drugs Alter Neurotransmission
Introducing artificial opiates (such as
heroin or morphine) may cause the brain
to stop producing naturally occurring
opiates (or endorphins).
 When the drug is withdrawn, the brain
may be deprived of any form of opiate,
causing intense discomfort.

The Nervous System
Peripheral Nervous System
 Made up of sensory and
motor neurons that
connect the CNS to the
rest of the body
 Involuntary and Voluntary
actions and movements
of the body
Central Nervous System
 Comprised of the brain
and spinal cord
 The spinal cord houses
the PNS and connects it
to the brain.
The Endocrine
System

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The body’s “slow” chemical
communication system, that is
interconnected with the
nervous system.
Secretes hormones, which
travel through the bloodstream
and effect other tissues.
The Pituitary Gland is
considered the “Master Gland”
because it influences growth
and controls other endocrine
glands.
The Brain
When we are thinking about our brain, we
are thinking with our brain.
 Brain + Body = Mind

– The mind is what the brain does.

The brain is the core organ that
determines who we are as individuals.
The Brainstem
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Oldest and most inner
region of the brain.
An extension of the spinal
cord
The place where nerves
“cross over” from one
side of the brain to the
other.
Responsible for
heartbeat, breathing and
coordination of
movement.
The Thalamus
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Sits on top of the
Brainstem.
Considered the sensory
switchboard.
Receives information from
all of the senses, except
smell and routes it to
higher brain regions.
Hub of the sensory
system.
The Cerebellum
Sits at the rear of the brainstem,
otherwise known as the “little brain”.
 Aids in modulating emotions,
discriminating sounds and textures, as
well as
coordinating
movements.

The Limbic System

Comprised of 3 main
parts
– Hippocampus: process
memory
– Amygdala: influences
aggression and fear
– Hypothalamus: directs
maintenance activities,
including eating, drinking,
body temperature, and is
linked to emotion and
reward.
The Cerebral Cortex
The 2 large hemispheres of the brain
(right and left) are called the cerebrum.
 The cerebrum is covered by a thin neural
network called the cerebral cortex, which
is the body’s ultimate control and
information processing center.
 The cerebral cortex is made up of 4 main
lobes.

The Lobes of the Cortex
Frontal Lobes
 Lies just behind the
forehead
 Involved in speaking and
muscle movement
 Decision making,
planning and judgment
 Includes the motor cortex
– controls voluntary
movement on the
opposite side of body.
Parietal Lobes
 Sits at top of head and
toward rear
 Includes the sensory
cortex
– Receives sensory input for
touch and body position
The Lobes of the Cortex
Occipital Lobes
Temporal Lobes
 Lies at the back of the  Lies roughly above
head
the ears
 Receives visual
 Responsible for
information
auditory processing
 Receives information
from the opposite ear
The Brain’s Plasticity
The brain is able to modify itself after
some type of damage.
 Fully functioning sections of the brain can
compensate for damaged regions.

– Constrait-induced therapy
Our brains are more plastic in childhood,
but we are able to retrain our brains even
as adults.
 Video on Brain Plasticity

The Hemispheres of the Brain
The left and right hemispheres of the
brain are connected by the corpus
callosum.
 The left hemisphere is primarily in charge
of verbal language.
 The right hemisphere is primary in charge
of visual perception and recogntion of
emotion.

Splitting the Brain
People with epileptic seizures, benefit from
the corpus callosum being severed, in turn
splitting the hemispheres.
 No communication occurs between each
side of the brain.
 Most people are able to live normal lives
despite the brain being split.
 Video
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