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The Brain and The Mind
Today’s Outline
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Nervous System
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Sensation & Perception
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Overview of nervous systems
Neuron communication
Peripheral nervous system
Overview of sensory channels
The case of vision
Summary of The Brain & The Mind
Characteristics
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Complex
Integrated
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Adaptable
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Transmit messages
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Biological Bases of Mental Life
Nervous system
Peripheral nervous system
(PNS): carries information to
and from the CNS
Somatic nervous
system: conveys
sensory information to
the CNS and sends
messages to muscles
Central nervous system
(CNS): Directs basic life
processes
Autonomic nervous
system: serves
basic life functions
(heart beat, stress
response)
Sympathetic
nervous system:
readies the body in
response to threat;
activation
Spinal Cord: receives
and sends messages
to brain and muscles
Parasympathetic
nervous system:
calms body down;
maintains energy
Brain: Directs activity,
processes
information; maintains
life support
Neurons: The Communicators
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Neurons are cells that communicate within
the nervous system
10-100 billion in the brain alone, each
communicating with thousands of others
Anatomy of a Neuron
Cell body: life support, contains
fatty substances and nucleus
Axon: Extension that sends
information to other cells
Action Potential: electric impulse
based on balance of ions in
the cell, all or none
Myelin Sheath: contains electrical
signal (prevents crossover &
facilitates transmission
Dendrites: receives information
from other cells, multiple
signals are then combined
The Role of Neurotransmitters
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Neurons do not actually touch –
there is a synapse between the
axon of one neuron and the
dendrites of the next
Neurotransmitters (chemicals)
cross this gap
Act like keys into locks of
postsynaptic neuron
This changes the ion balance in the
next neuron (excite or inhibit)
Those that do not bind are taken
back up by the sending neuron or
dissolved by other cells
Major Neurotransmitters
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Acetylcholine (ACh): Muscle action, learning &
memory
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Dopamine: Movement, learning, attention, memory
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Problems:
Serotonin: Mood, hunger, sleep, arousal
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Problems:
Problems:
Norepinephrine: alertness, arousal
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Problems:
Video: Psychoactive Drugs
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What neurotransmitter do psychoactive drugs
emulate?
Why are they a problem?
What does the body do when too much of a
transmitter is dumped?
The Peripheral
Nervous System
Arousal vs. Calming
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Autonomic Nervous System: controls glands &
muscles of internal organs, can be consciously
overridden but often acts on its own
Sympathetic: arouses
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Accelerated heart beat, increased blood pressure,
slow digestion, raise blood sugar, sweat, prepare for
action
Can prepare for aggressive action (fight or flight) or
protective action (tend and befriend)
Parasympathetic: calms & conserves energy
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Undoes what the sympathetic system does
When it goes wrong…
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Normally, the sympathetic & parasympathetic
work together to maintain balance
Sympathetic can become over engaged
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Sympathetic can be under engaged
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General areas in the brain
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Hindbrain
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Midbrain
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Lowest portion of the brain
Between hind and forebrain
Forebrain
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Includes the cerebral cortex
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Highest region
Sensation & Perception
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The interplay between the external world,
physiological systems, and psychological
experience
How the external world makes “impressions”
on our nervous system & how the nervous
system organizes those impressions
Working Together
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Sensations:
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Perception:
Sensing the World
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Happens through our senses
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Vision, hearing, taste, smell, proprioceptive (touch/
movement)
System specific stimuli
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Each system has a form of energy that it can detect and
process
Physical energy must exceed absolute thresholds (in some
cases must also exceed other thresholds)
Has transduction mechanisms to change physical energy
into neural information then sends to specific brain areas
Vision
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Eye detects electromagnetic radiation (light)
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Movement
Color
Light travels quickly, travels in straight lines,
interacts with surfaces in the environment (is
reflected or absorbed)
Perceptual Processes
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Identifying everything and documenting it in
detail is a lot of work, so your visual system
takes shortcuts
Our expectancies can guide what we see
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Gestalt principles of vision
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Help us quickly identify
Depth Perception
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The environment
provides cues for
perception
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These linear cues
are often functional
Size Constancy
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We see objects as maintaining their size
The Brain & The Mind
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The brain gives rise to all conceptions of
“mind”
Sensory systems pick up energy from the
environment and transduce it to
neurological impulses
These impulses are transferred to the
brain
Thus our knowledge of the world is an
interactive process