Lesson 2: Neurons and Neural Firing

Question 1

Neural Substrates of Cognition

Answer 1

Perception, attention, memory, language, decision-making, problem solving, consciousness

Question 2

Axon

Answer 2

Dendrites
Soma (nucleus)
Axon
Axon Terminals

Question 3

Neurons

Answer 3

Connected via synapse and come in different shapes, sizes, and connections

Question 4

Dendrites vs Axons

Answer 4

Dendrites receive the signal and axons send signals. Axons have an active current and dendrites have a passive current.

Question 5

How does the signal travel from neuron to neuron? (1)

Answer 5

1. Neurons receive signals in chemical or physical from (neurotransmitters).
   - Receptor cells (sensory neurons - pressure) or interneurons (chemical neurotransmitters)
   - NT’s bind to receptors of next neuron and Na+ channels open = depolarization (passive)

Question 6

How does the signal travel from neuron to neuron? (2)

Answer 6

2. Sodium diffuses down through the dendrites and cell body

Question 7

How does the signal travel from neuron to neuron? (3)

Answer 7

Electrical signal activated and travels quickly down axon to axon terminals
- only if the current is strong enough when it reaches the axon
- size of neuron, ISPS, and how far dendrite is from axon affect how strong current is

Question 8

Action Potentials (3)

Answer 8

• Only in axons
• 100 m/s
• Constant in strength as they move (no signal loss)
• Inside cell is negative (K+) and outside is positive (Na+(
• Resting potential: -70 mV

Question 9

Action Potential Steps

Answer 9

Sodium form previous AP depolarize cell until -55 mV reached then sodium channels open on current cella nd continue to depolarize until +30 mV, then Na+ close an dK+ opens and comes out of cell then hyperpolarizes until -90 mV then Na+/K+ pump brings it back to RP (3 Na+ out, 2 K+ in)

Question 10

Refractory period and Threshold

Answer 10

Threshold hits at different points on the axon all the way down
Refractory Period: Na+ closes and AP moves in only one direction

Question 11

Myelin Sheaths

Answer 11

• Makes AP travel fatser
• Ion channels in them do not open, but they open at nodes of ranvier and generate AP to travel down myelin sheath quickly (less E)
• Allows it to keep constant strength

Question 12

All or None Law

Answer 12

AP either fires or it does not fire, magnitude of AP does not depend on stimulus

Question 13

How does the signal travel from neuron to neuron? (4)

Answer 13

NT’s release at the synapse and process starts over

Question 14

Intensity Coding

Answer 14

How strong a stimulu is (each line = action potential)
- More intense stimulus = more AP’s of the same strength!

Question 15

Quality Coding

Answer 15

Patterns of neural firing and codes quality of stimulus

Question 16

Different Qualities Activate Different Neurons

Answer 16

• Feature detectors in visual system makes neurons respond to certain things

Question 17

Conscious Perception

Answer 17

Feature detectors develop as you’re expsed to certain stimuli
- outside of critical time period of development makes it harder to develop
- Cats and lines

Question 18

Temporal Cortex Neurons

Answer 18

Specific neurons respond to specific stimuli. quality

Question 19

Specificity Coding

Answer 19

Specific neuron responds to specific stimuli

Question 20

Sparse Coding

Answer 20

Subset of neurons in a population will fire in different patterns for a specific stimuli

Question 21

Population

Answer 21

All cells respond to stimuli in a different amount