Yang Lecture 1 Flashcards
What are systems in neuroscience?
the science of networks/circuits of neurons having specific functions
What are the 4 codes of neurons that form neural circuits?
PYR: pyramidal neuron
PV+: parvalbumin-expressing interneuron
SST+: Somatostatin-expressing interneuron
VIP+: vasointestinal peptide-expressing interneuron
Why are neural circuits important?
The action potential produced by these different neurons mean different things.
What does action potential frequency tell us?
Firing rate codes for the strength of a sensory signal
What is coordinated activity in neural coding?
Precision of spikes among different neurons
What is an example of synchrony code?
EEG: electroencephalography
- records during moony face recognition in human subjects
What is graded potential?
Amplitude of depolarization codes for the strength of the sensory signal
What is the relationship between depolarization and amount of transmitter released?
The more depolarization, the more transmitter is released
What is the central pathway?
Sensory signal is transmitted from peripheral neurons to central neurons in the brain
periphery -> subcortical -> cortical
What’s the function of sensory receptor cells?
Transduce energy of different forms to electrical activity so that can be passed on to other neurons
What is a receptive field?
the location in the environment from which the appropriate stimulus will change that cell’s activity
What does a topographic map show us?
There can be overlapping receptive fields
- orderly representation of sensory space in the nervous system
What’s the pupil?
Opening that allows light to enter the eye
What’s the iris?
surrounds pupil (eye color) and contains muscles that can change the size of pupil
What’s the cornea?
covers pupil and iris for light refraction
What’s the sclera?
White of the eye
- tough outer wall
What do extraocular muscles do?
move the eye
What’s the purpose of the retina?
Phototransduction occurs here
- several thin layers of cells distributed across the inside of the eye
What’s the purpose of the fovea?
Highest acuity for details
- light directly shines here
What’s the optic disk and the function?
axons from a retinal cell collect and exit the eye to form the optic nerve
- blind spot because there’s no photoreceptors
What are the 5 layers of cells in the retina?
Light enters:
- retinal ganglion cells
- amacrine cells
- bipolar cells
- horizontal cells
- photoreceptor cells
How do bipolar cells work?
Photoreceptor cells project onto them
What’s the importance of the retinal ganglion cell?
ONLY output cell type in the retina
- how information gets from the eye to visual system
What cells are present in the fovea?
Only photoreceptors
- the other cells move to the side
What layers are translucent in the retina?
All except the photoreceptor cells
- light has to pass through all the layers to get to the photoreceptors
Compare and contrast rods and cones
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
How does information process in the retina? (linear pathway)
Photoreceptor cells project to bipolar cells and retinal ganglion cells send the information to the visual system
How does information process in the retina? (Lateral pathway)
Retinal ganglion cells and bipolar cells project to amacrine cells
Bipolar cells and photoreceptor cells project to horizontal cells
Which cells use graded depolarization, and which use action potential?
Retinal ganglion cells and amacrine cells use action potential
Bipolar, horizontal, and photoreceptors use graded depolarization
How do cones detect light?
Specific wavelengths!
- blue: 430 nm
- green: 530 nm
- Red: 560 nm
What is phototransduction?
how light energy leads to a change in membrane potential
How do photoreceptor cells work in the dark?
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
How do photoreceptor cells work in the light?
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
Why is g-protein cascade important?
Fast amplification
How does light send signals to the brain?
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
How does light intensity change with membrane potential and glutamate release?
Dark: -30 mV resting and high glutamate release
Moderate: -30 to -65 mV with moderate glutamate release
Bright: -65 mV with little glutamate release
