1. Nervous System Function
Neurons
Base unit that has very simple function – “decide” whether to transmit signal or not
Organization
Billions of Neurons (estimates of 100 billion)
Very complex interconnections
Create systems/circuits that can function independently (parallel processing)
“Simple decisions” passed to “higher” levels for that add additional information to create generate more complex decisions (hierarchical processing)
Very expensive - less than 2% of weight but uses 20% of energy

2. Neuron Structure Cell Body Dendrites Axon Axon Terminals
Nucleus – genetic information
Dendrites
Receive information
Axon
Carry information “long” distances
Myelin (Multiple Sclerosis)
Axon Terminals
Transmit information

3. Neuron - Structure

4. Neuron Function Electrical Activity Chemical Activity
Used to transmit signal within neuron
Chemical Activity
Used to transmit signal between neurons
Synapse – small gap that physically separates neurons
Neurotransmitters – special “chemicals” that neurons use to transmit message across the synapse

5. Neuron - Synapse

6. Synapse Function Neurotransmitter cycle in Axon Terminals
Synthesis
Storage
Release
Inactivation
Reuptake
Degradation
Neural transmission problems if cycle disrupted (e.g., drugs) at any step

7. Synapse Function

8. Synapse Function

9. Nervous System Organization
Central Nervous System (CNS)
Spinal Cord – simple decisions & information transmission
Brain – “complex” decisions
Peripheral Nervous System (PNS)
Somatic – sensory information & voluntary movement
Autonomic
Sympathetic – increases support increased physical activity
Parasympathetic – increases support decreased physical activity
Enteric – gastrointestinal system

10. Nervous System Organization

11. Autonomic Nervous System

12. Spinal Cord
31 segments with pairs (left & right) nerves carrying sensory and efferent information
Functions
Ascending and descending neural tracts
Interneurons responsible for spinal reflexes (relatively simple decisions)
Link sensory information (e.g., pain) with motor response (e.g., muscle contraction)

14. Brain Structure Very Complex General Principles
Many different ways of describing brain structures (location, function, etc.)
General Principles
Layered
Lateralized

18. Brain Neural Systems Brain circuits responsible for brain function
E.g., - vision, hearing, movement, reward
System could be
Localized (vision) or diffuse (arousal)
General (vision) or specific (color vision)
Broad Divisions
Sensory
Motor
Association

19. Brain
Complex behaviors (fear/defensive learning) depend on many systems
Sensory
Learning
Memory
Output
Differences in a function (e.g., motivation) might be due to different reasons (e.g., sensory, learning, etc.)