Yang Lecture 1

Question 1

What are systems in neuroscience?

Answer 1

the science of networks/circuits of neurons having specific functions

Question 2

What are the 4 codes of neurons that form neural circuits?

Answer 2

PYR: pyramidal neuron
PV+: parvalbumin-expressing interneuron
SST+: Somatostatin-expressing interneuron
VIP+: vasointestinal peptide-expressing interneuron

Question 3

Why are neural circuits important?

Answer 3

The action potential produced by these different neurons mean different things.

Question 4

What does action potential frequency tell us?

Answer 4

Firing rate codes for the strength of a sensory signal

Question 5

What is coordinated activity in neural coding?

Answer 5

Precision of spikes among different neurons

Question 6

What is an example of synchrony code?

Answer 6

EEG: electroencephalography
- records during moony face recognition in human subjects

Question 7

What is graded potential?

Answer 7

Amplitude of depolarization codes for the strength of the sensory signal

Question 8

What is the relationship between depolarization and amount of transmitter released?

Answer 8

The more depolarization, the more transmitter is released

Question 9

What is the central pathway?

Answer 9

Sensory signal is transmitted from peripheral neurons to central neurons in the brain
periphery -> subcortical -> cortical

Question 10

What’s the function of sensory receptor cells?

Answer 10

Transduce energy of different forms to electrical activity so that can be passed on to other neurons

Question 11

What is a receptive field?

Answer 11

the location in the environment from which the appropriate stimulus will change that cell’s activity

Question 12

What does a topographic map show us?

Answer 12

There can be overlapping receptive fields
- orderly representation of sensory space in the nervous system

Question 13

What’s the pupil?

Answer 13

Opening that allows light to enter the eye

Question 14

What’s the iris?

Answer 14

surrounds pupil (eye color) and contains muscles that can change the size of pupil

Question 15

What’s the cornea?

Answer 15

covers pupil and iris for light refraction

Question 16

What’s the sclera?

Answer 16

White of the eye
- tough outer wall

Question 17

What do extraocular muscles do?

Answer 17

move the eye

Question 18

What’s the purpose of the retina?

Answer 18

Phototransduction occurs here
- several thin layers of cells distributed across the inside of the eye

Question 19

What’s the purpose of the fovea?

Answer 19

Highest acuity for details
- light directly shines here

Question 20

What’s the optic disk and the function?

Answer 20

axons from a retinal cell collect and exit the eye to form the optic nerve
- blind spot because there’s no photoreceptors

Question 21

What are the 5 layers of cells in the retina?

Answer 21

Light enters:
- retinal ganglion cells
- amacrine cells
- bipolar cells
- horizontal cells
- photoreceptor cells

Question 22

How do bipolar cells work?

Answer 22

Photoreceptor cells project onto them

Question 22

What’s the importance of the retinal ganglion cell?

Answer 22

ONLY output cell type in the retina
- how information gets from the eye to visual system

Question 23

What cells are present in the fovea?

Answer 23

Only photoreceptors
- the other cells move to the side

Question 24

What layers are translucent in the retina?

Answer 24

All except the photoreceptor cells
- light has to pass through all the layers to get to the photoreceptors

Question 25

Compare and contrast rods and cones

Answer 25

BOTH: Photoreceptors cells
Rods: good in dim light
- sensitive to light and bleached in bright light
- not good for fine details
- achromatic
- exist outside the fovea
Cones: sensitive to color
- concentrated in fovea

Question 26

How does information process in the retina? (linear pathway)

Answer 26

Photoreceptor cells project to bipolar cells and retinal ganglion cells send the information to the visual system

Question 27

How does information process in the retina? (Lateral pathway)

Answer 27

Retinal ganglion cells and bipolar cells project to amacrine cells
Bipolar cells and photoreceptor cells project to horizontal cells

Question 28

Which cells use graded depolarization, and which use action potential?

Answer 28

Retinal ganglion cells and amacrine cells use action potential
Bipolar, horizontal, and photoreceptors use graded depolarization

Question 29

How do cones detect light?

Answer 29

Specific wavelengths!
- blue: 430 nm
- green: 530 nm
- Red: 560 nm

Question 30

What is phototransduction?

Answer 30

how light energy leads to a change in membrane potential

Question 31

How do photoreceptor cells work in the dark?

Answer 31

1) Intracellular cGMP binds to cGMP gated Na+ channels
2) cGMP keeps the channel open and allows Na+ influx
3) Photoreceptor cell membrane is kept depolarized at -30 mV
4) Glutamate (neurotransmitter) is constantly released at the terminal

Question 32

How do photoreceptor cells work in the light?

Answer 32

1) Light stimulation reduces cGMP
2) Na+ channel closes and allows the membrane to hyperpolarize to -65 mV
3) Glutamate release stops at the terminal

Question 33

Why is g-protein cascade important?

Answer 33

Fast amplification

Question 34

How does light send signals to the brain?

Answer 34

1) Light charges 11-cis-retinal to all-trans-retinal
2) Transducin-GDP separates into alpha and beta/gamma subunits and GDP swaps with GTP
3) T(alpha)-GTP activated cGMP phosphodiesterase
4) cGMP converts to GMP and lowers [cGMP]
5) Na+ channels close and hyperpolarization occurs

Question 35

How does light intensity change with membrane potential and glutamate release?

Answer 35

Dark: -30 mV resting and high glutamate release
Moderate: -30 to -65 mV with moderate glutamate release
Bright: -65 mV with little glutamate release