1. Starting small: The Neuron
neuron: a nerve cell; receives signals from other neurons or sensory organs, processes these signals, and sends signals to other neurons, muscles, or bodily organs
the basic unit of the nervous system

2. The Neuron 3 types of neurons:
1. sensory neurons: respond to input from sensory organs (skin, eyes, etc.)
2. motor neurons: send signals to muscles to control movement
3. interneurons: connect the sensory neurons and motor neurons
most of the neurons in the brain = interneurons
average human brain  100 billion neurons

3. Structure of the Neuron

4. Structure of the Neuron
cell body (soma): the central part of the neuron, contains the nucleus
regulates cell functioning
dendrites: the branching part of the neuron that receives messages from other neurons and relays them to the cell body

5. Structure of the Neuron
axon: the long, cable-like extension that delivers messages to other neurons
myelin sheath: layer of fatty tissue that insulates the axon and helps speed up message transmission
multiple sclerosis: deterioration of myelin leads to slowed communication with muscles and impaired sensation in limbs
knobs: structure at the end of one of the axon’s branches that releases chemicals into the space between neurons, when the neuron is fired

6. From Neuron to Neuron
≈100 billion neurons in a human brain, connected to an average of 10,000 others; some up to 100,000
synapse: the place where an axon of one neuron meets with the dendrite/cell body of another neuron

7. From Neuron to Neuron

8. From Neuron to Neuron
neurotransmitters: a chemical that sends signals from one neuron to another over the synapse

9. From Neuron to Neuron
Neurotransmitters are stored in vesicles in the knobs, and bind to receptors on the cell membrane of the next neuron.
Each receptor can only bind with one kind of neurotransmitter.

10. (Some) Neurotransmitters
Function
Examples of malfunctions
Acetylcholine (ACh)
Enables muscle action, learning & memory
Alzheimer’s disease  less ACh production
Dopamine
Influences movement, learning, attention, & emotion
Excess  schizophrenia
Undersupply  Parkinson’s disease
Serotonin
Affects mood, hunger, sleep, and arousal
Undersupply  depression
Norepinephrine
Helps control alertness & arousal
Undersupply  depressed mood
Glutamate
Excitatory neurotransmitter involved in memory
Excess  overstimulation of brain, seizures

11. The Nervous System
comprised of the central nervous system and the peripheral nervous system
central nervous system: brain and spinal cord
reflex: an automatic response to an event
e.g. sensory neuron detects pain, send signal to spinal cord  signal to interneurons  signal to motor neurons

12. The Nervous System
Peripheral Nervous System: links central nervous system to organs
comprised of the skeletal nervous system and the autonomic nervous system
skeletal nervous system: controls voluntary movements of our skeletal muscles

13. The Nervous System
autonomic nervous system: controls many of the self-regulatory functions of the body (e.g. digestion, circulation)
comprised of the sympathetic and parasympathetic nervous systems
sympathetic: prepares us for defensive actions against threats (e.g. faster heartrate, increased breathing rate, inhibits digestion, dilates pupils to allow greater light sensitivity)
parasympathetic: counteracts effects of sympathetic nervous system, calms us down

14. Structure of the Brain
The human brain is comprised of “older” and “newer” parts.
“older”: lower level structures, responsible for basic survival mechanisms
“newer”: higher level structures, responsible for more advanced human faculties

15. Structure of the Brain
brainstem: the set of neural structures at the base of the brain, including the medulla, the reticular formation, and the pons
facilitates communication between the brain and spinal cord

16. The Brainstem medulla: controls heartbeat, breathing, and swallowing
pons: bridge from brainstem to cerebellum; controls a variety of functions, including sleep and control of facial muscles

17. The Cerebellum “little brain” extending from rear of brainstem
coordinates physical movement
contributes to estimating time and paying attention
cerebellum + other lower level brain structures occur without conscious effort
Much of our brain’s activity occurs outside of our awareness

18. The Brainstem
thalamus: the brain’s sensory switchboard; receives signals from the sensory and motor systems, and relays them to the appropriate parts of the brain
also receives signals from higher brain structures, relays them to medulla and cerebellum

19. The Limbic System
limbic system: doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres
involved in the basics of emotion and motivation: fighting, fleeing, feeding, and sex
comprised primarily of the hypothalamus, the hippocampus, and the amygdala

20. The Limbic System
hypothalamus: brain structure that sits under the thalamus and plays a central role in controlling eating and drinking, and in regulating the body’s temperature, blood pressure, and heart rate

21. The Limbic System
hippocampus: brain structure that plays a key role in allowing new information to be stored in memory
hippocampus does not contain memories itself, but does trigger processes that store memories elsewhere in the brain

22. The Visible Brain
cerebral cortex: the convoluted pinkish-gray surface of the brain, where most mental processes take place
The brain is divided into two halves (cerebral hemispheres), separated by a deep fissure
hemispheres control opposite side of body (e.g. right-handers’ writing is controlled by the left hemisphere)
in-class demo:
rotate right hand clockwise
simultaneously rotate right foot clockwise (easy)
simultaneously rotate right foot counter-clockwise (hard)
simultaneously rotate left foot counter-clockwise (easy; different hemispheres)

23. Our Divided Brains
cerebral hemispheres connected by the corpus callosum, a large band of neural fibers that transmits messages between hemispheres
contains more than 200 million nerve fibers, can transfer more than 1 billion bits of information per second

24. Structure of the Cortex
cerebral cortex divided into lobes, or regions of the brain
Each lobe is (roughly) responsible for different higher-level functions, but remember that they do not work merely in isolation.

25. Structure of the Cortex
occipital lobe: brain lobe at the back of the head
responsible primarily for vision; separate areas specify visual properties such as shape, color, and motion

26. Structure of the Cortex
temporal lobe: the brain lobe under the temples, in front of the ears
many functions, including processing sounds, committing information to memory, and comprehending language

27. Structure of the Cortex
parietal lobe: brain lobe at the top and center/rear of the head
involved in registering spatial location, attention, and motor control

28. Structure of the Cortex
frontal lobe: the brain lobe located behind the forehead
the seat of planning, memory search, motor control, reasoning, emotions, and many other functions
In many ways, the frontal lobe is what makes us uniquely human.