Guest Lecture - Week 8

Types of methods to study neuro

Explain the difficulty on differentiating cells and their purposes

One cell may have multiple purpose

Cells are hard to detect spatially too

• Either sparsely distributed

• Or intermingled with other tissue

What light + virus transfer is used to drive action potential? (Optogenetics)

Blue light, Channelrhodopsin (ChR2)

Why are optogenetics used

Milliseconds of control + change that can be detected

How can optogenetics excite neurons

Pushing positive ions through channels for AP

How can optogenetics silence neurons

Pushing negative ions through channels —> prevent AP

What light + virus transfer is used to inhibit/silence action potential? (Optogenetics)

Orange light, Halorhodopsin (CeNpHR),

What does chemogenetics use for control

DREADs —> proteins engineered to target specific cell

Process of firing DREADs

Stimulate DREAD by CNO ligand

How are ligands transferred into the brain

Implanting or injections

• Don’t get temporal resolution though

• More animal friendly

Which ligand enhances neural firing

hM3Dq

Which ligand silences neural firing

hM4D

Chemo vs opto

Opto has better temporal resolution (milliseconds)

Chemo has better animal friendly ethics via injections

Calcium imaging uses what & why?

GCaMP

• Helps track changes in neural activity

  • Lead to florescence to be activated

How many wavelengths are involved in calcium imaging & what are they used for

2 wavelengths, one to excite/inhibit, other to emit florescence

What helps the miniscope see more parts of the brain?

GRIN lenses - refracts light to micrscope

Why is calcium imaging used

Can see many cells working at once