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
 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
 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 Function
 Electrical Activity
 Resting Potential
 Inside negative (-70 mV) compared to outside
 Inside has high K+ (negativity comes from proteins
& other negative ions)
 Outside has high Na+
 Forces at work
 Electrical
 Diffusion

6. Neuron Function
 Electrical Activity
 Graded Potential
 Depolarization – Inside less negative (e.g., Na+ enters)
 Hyperpolarization – Inside more negative (e.g., Cl- enters)
 Action Potential
 When graded reaches approximately -55mV
 Electrical impulse that travels down cell – axon to axon
terminals
 Axon terminals release neurotransmitter

8. Neuron Function
 Electrical Activity
 Restoring Resting Potential
 Sodium-Potassium Pump – moves Na+ out of cell
and K+ into cell
 This requires cell to use energy

9. Neuron Function
 Chemical (Neurotransmitter) Activity
 Leads to graded potentials in neuron
 Excitatory NTs – causes depolarization in neuron
 Initiatory NTs – causes hyperpolarization in
neuron

10. Neuron – Excitation & Inhibition

11. Neuron - Synapse

12. Synapse Types
 Multiple ways of connecting
 Examples
 Axon to Dendrite – excite or inhibit neuron
 Axon to Axon Terminal – moderate NT release
 Axon to Extracellular Space or blood – potential
for diffuse effects

13. Synapse Types

14. 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

15. Synapse Function

16. Synapse Function

17. Neurotransmitter Types
 Small Molecules
 Nine – Acetylcholine (ACh), dopamine (DA),
norepinephrine (NE), epinephrine (adrenaline), serotonin
(5-HT), histamine, GABA, glycine, glutamate
 Simple (or no) alterations to basic food components
 Glutamate & glycine are amino acids
 DA and NE from tyrosine & 5-HT made from tryptophan
 Manufactured in axon terminals
 Large quantity and have short duration

18. Note: There are four criteria by which
neurotransmitters are defined.
 1. It must be synthesized in the
presynaptic cell.
2. It must be released by the presynaptic
terminal in sufficient quantities to produce
a measurable effect on the postsynaptic
cell.
3. When administered artificially, it mimics
natural release.
4. A specific, known mechanism exists for
it to be removed from the synaptic cleft.

19. Acetylcholine (ACh)
• -Arousal and orgasm
- voluntary muscular control and proper
tone
- enhance energy and stamina
- memory
- long-term planning
- mental focus

20. dopamine (DA)
 - Alertness
- Motivation
- motor control
- immune function
- Ego hardening,
confidence, optimism
- Sexual Desire
- Fat gain and loss
- lean muscle gain
- Bone density
- ability to sleep soundly
- Inhibits prolactin
- thinking, planning, and
problem solving
- Aggression
- Increase psychic and
creative ability
- Reduction of
compulsivety
- Salience and paranoia
- Processing of pain
- Increase sociability

21. norepinephrine (NE)
 - Increase physical
energy
- Reduce
compulsivety
- Increase heart rate
- Increase BP
- Aggression
- Alertness
- Wakefulness/sleep
cycle
- Memory and learning
- Orgasm
- Decrease blood flow to
extremities
- Increase heart rate
- Maintenance of
attention
- Cerebral plasticity

22. epinephrine (adrenaline)
 - increases supply of oxygen and glucose
to brain and muscles
- Surpresses digestion
- Increase heart rate and stroke volume
- Pupil dilation
- constricts arterioles in skin and GI tract
- Dilates arterioles in skeletal muscles
- Elevates blood sugar levels

23. serotonin (5-HT)
 - Decrease thought
- Anaesthesize emotions
- Decrease Agression and anger
- Decrease Anxiety
- Promote satiety and decrease
appetite
- Elevates Pain threshold
- Reduces
compulsivety/impulsivety
- Decrease Sexual Desire
- Thermoregulation (5-HT1A)
- Stimulate Emesis (5-HT3)
- Cerebrospinal fluid secretion (5-
HT2C)
- Platelate aggregation (5-HT2A)
- Smooth muscle contraction,
vasoconstriction, and vasodilation (5-
HT2A)
- Release oxytocin (5-HT1A)
- Learning (5-HT2A & 5-HT4)
- Memory (5-HT4)
- Neuronal excitation (5-HT2A, 5-HT3,
& 5-HT4)
- GI motility (5-HT4)
- Neuronal inhibition (5-HT1A)
- Cerebral vasoconstriction (5-HT1D)
- Pulmonary vasoconstriction (5-
HT1B)
- Presynaptic inhbition (5-HT1B)

24. histamine H1
- Vasodilation
- Bronchoconstriction
- Smooth muscle activation
- separation of endothelial cells (responsible for hives)
- Pain and itching due to insect stings
- Allergic rhinitis
- Motion sickness
H2
- stimulates gastric acid secretion
- Potent stimulant of cAMP production
- increases the intracellular Ca2+ concentrations and release Ca2+ from intracellular
stores.
H3
- presynaptically inhibits the release of a number of other neurotransmitters
including, but probably not
limited to dopamine, histamine, GABA, acetylcholine, noradrenaline, and 5-HT. It
leads to inhibition of the formation of cAMP
H4
- H4 Receptors mediate Chemotaxis and Calcium Mobilization of Mast Cells

25. GABA - synthesized from glutamate
 - Reduce physical tension
- Reduce Anxiety
- Reduce Insomnia
- Elevates pain threshold
- Reduces blood pressure
- Decrease heart rate
- Reduce compulsivety

26. Glycine
Glutamate and Aspartate
 excitatory neurotransmitters

27. Neurotransmitter Types
 Peptides
 50+ and grouped into families depending on function
 Opoids (enkephalins, dynorphin) – pain
 Gastrins (gastrin, cholocystokinin) – food digestion
 2 or more amino acids and made in cell body (ribosomes)
from DNA instruction
 Slower to manufacture & transport
 Small concentrations and longer durations
 Gases
 At least 2 – nitric oxide (NO) & carbon monoxide (CO)
 Can work on releasing cell

28. Neurotransmitter Function
 No one to one relation between type and
function
 Same NT can be used in different places with
very different effects
 Acetylcholine – contracts muscles, used in
autonomic nervous system, and brain

29. Neurotransmitter Receptor Proteins
 Channel Proteins
 NT binding site and channel trough membrane
 NT opens a channel to allow chemical flow (Na+) across
membrane
 Second Messengers
 NT binding site – NT activates a “second messenger” (1st
is the NT) inside the cell
 Change function of cell (e.g., change protein production to
permanently alter cell function for learning)

30. Neurotransmitter Receptor Proteins

31. Neurotransmitter Receptor Proteins
 Usually multiple receptors for a given NT
 Acetylcholine
 Nicotinic receptor – found a junction between
neuron and muscle
 Muscarinic receptor – more prevalent in brain
 Acetylcholine affects both
 Drugs can have more specific effects (or not
depending on the drug)
 Nicotine & curare –affect nicotinic but not muscarinic

32. Neurotransmitter Receptor Proteins
 Usually multiple receptors for a given NT
 Serotonin (5-HT)
 13 known receptors grouped into 6 families
 People with schizophrenia have an excess of one
type
 Demonstrates how genetic differences can influence
motivational temperaments
 Dopamine
 5 known receptors grouped into 2 families

33. Psychoactive Drug Overview
 Two Broad effects on NT function
 Facilitate or increase function of a specific NT
 Inhibit or Decrease function of a specific NT
 2 Broad effects accomplished by altering
any of the 7 synapse functions (previous
slide)
 Acetylcholine

34. Psychoactive Drug Overview
 Acetylcohine Example
 Axon Release
 Black widow spider venom – released from axon terminals
 Botulinum toxin (Botox) – blocks release from axon
terminals
 Synapse Stimulation
 Nicotine – mimics ACh
 Curare – blocks ACh from getting to terminals
 Inactivation
 Physostigmine – blocks effect of enzyme that destroys ACh

35. Psychoactive Drug Overview

36. Psychoactive Drug Overview
 Nervous System adapts drug presence
 Inhibitory drug – may create more protein
receptors to detect smaller amounts of NTs that
are getting to postsynaptic cell
 Excitatory drug – may remove protein receptors
 NS now requires drug for functioning
 Inhibitory drug – “normal” signals are too strong
 Excitatory drug – “normal” signals not strong
enough

37. Nervous System Organization

38. 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

39. Autonomic Nervous System

40. Nervous System Organization
 Neuron Groups
 Peripheral NS
 Nerve – collection of axons in PNS
 Ganglia – collection of cell bodies & dendrites
 Central NS
 Tract – collection of axons in CNS (White Matter)
 Nuclei – collection of cell bodies (Grey Matter)
 Glial Cells
 Support and assist neurons (many types)
 Produce myelin, nourishment, repair, waist disposal, etc.

41. 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)

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

47. 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

48. 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.)

49. Studying Brain Function
 Gross lesions
 Structural assessments
 Selective lesions
 specific neurotoxins
 transient lesions
 Local functioning
 Single-cell recording
 Neurotransmitter measurement & manipulation
 Gene expressions
 Non-invasive measures
 Functional MRI
 EEG & ERP