Lecture 3-4

Question 1

Magnetic respnance imaging (MRI)

Answer 1

A method of structural neuroimaging based on recording changes in magnetic fields that provides good contrast when looking at soft tissues (brain, abdomen, ligaments)

Question 2

Diffusion tensor imaging (DTI)

Answer 2

A type of MRI that measures structural connections between brain regions based on the diffusion of water molecules

Question 3

Pros of MRI technique

Answer 3

non-invasive, can be done in humans, and can be repeatedly done for longitudinal observations

Question 4

Cons of MRi technique

Answer 4

Limited spatial resolution, claustrophobia, and anesthesia for non-human animals may be needed

Question 5

Green fluorescent protein (GFP)

Answer 5

Originally isolated from jellyfish, can be fused to the gene of a protein in interest so that the protein can be made alongside with the green fluorescence that can respond to blue to ultraviolet light

Question 6

Anterograde tracers are taken up by ____ and transported along ____

Answer 6

somas; axons
(where do you send your axons?)

Question 7

Retrograde tracers are taken up by ____ ____ and transported along axons back to the ____

Answer 7

axon terminals; soma
(where are you from)

Question 8

Pros of anatomical tracers (anterograde/retrograde tracers)

Answer 8

good spatial resolution, and are projection and cell type specific

Question 9

Cons of anatomical tracers

Answer 9

Single temporal snapshot, and are limited to non-human animals

Question 10

Functional MRI (fMRI)

Answer 10

Indirect measurement of brain activity through measuring oxygen intake at brain areas wikth 4-6 sec delay

Question 11

Pros of fMRI

Answer 11

non-invasive, can be done repeatedly, and can combine brain physiology with behavior since it can be done while performing cognitive tasks

Question 12

Cons of fMRI

Answer 12

poor temporal resolution, blood oxygenation is indirect measure of neural activity, and very expensive!

Question 13

Electroencephalography (EEG)

Answer 13

A method for measuring electrical activity in the brain by means of electrodes placed on the scalp

Question 14

Since different patterns of oscillations occur during different stages of sleep, sleep stages are defined by the patterns present in the ____ (____)

Answer 14

Electroencephalography (EEG)

Question 15

Pros of EEG

Answer 15

non-invasive, can be done repeatedly, and combines brain physiology with behavior

Question 16

Cons of EEG

Answer 16

Poor spatial resolution, and is a measure of aggregate neural activity rather than single neuron

Question 17

in vivo single neuron recording

Answer 17

Surgically implant electrodes into brain region of interest and extracellularly record action potentials generated by individual neurons while recoding behavior of animal at the same time, thus relating firing of single neuron to some external stimulu or the behavior of the animal.

Question 18

Pros of in vivo single neuron recording

Answer 18

single neuron resolution (very precise), millisecond temporal resolution (VERY precise), and combines brain physiology with behavior

Question 19

Cons of in vivo single neuron recording

Answer 19

Difficult to track some neuron over days (cuz we’re inserting by LUCK), can only monitor a few dozen neurons at a time, HIGHLY INVASIVE (like u actually need to drill it into your skull), and the animal’s movement can be restricted by the tether connected to the tetrodes

Question 20

Calcium imaging

Answer 20

Uses calcium indicators that fluorest when neurons fire action potential (when calcium flows into the soma).
*Implant optical lens above the population of neurons needed so a microscope can be attached to it and visualize neurons

Question 21

____ imaging can monitor 100s of neurons simultaneously, and can track the same neurons over time since the ____ ____ remains in the same location (though it does damage).

Answer 21

Calcium; optical lens

Question 22

Cons of calcium imaging

Answer 22

Is an indirect measure of action potentials, poor temporal resolution due to its slow decay, highly invasive and lots of damage, and the animal’s movement is restricted by a tether

Question 23

Engram

Answer 23

the physical instantiation in the brain that forms the basis of a memory (also referred to as a memory trace)

Question 24

Karl Lashley trained a group of rats to navigate a maze and then leshioned different areas of the cortex in each rat. He found that…

Answer 24

no one cortical area seemed to be more important than any other, and performance following lesion depended more on the size of the lesion than its location

Question 25

Reversible “lesions”

Answer 25

A pharmacological inactivation of a brain region by maintaining membrane potential of neurons in that region well below action potential threshold, thus silencing that brain region.

Question 26

Following ____ ____, recovery of function is not an issue, but the initial ____ is made directly into the brain region and can cause damage to it.

Answer 26

reversible lesions; injection

Question 27

____ involves using ____ receptors that doesn’t respond to any ____ chemicals and has been engineered to ____ or ____ neurons when synthetic compound binds.

Answer 27

Chemogenetics; synthetic; endogenous; excite; inhibit

Question 28

How are synthetic compounds in chemogenetics administered?

Answer 28

orally or injection
(therefore can be used to study the PNS!)

Question 29

Optogenetics

Answer 29

Light sensitive proteins are expressed in a specific population of neurons, making them responsive to specific wavelengths of light

Question 30

In optogenetics, ____rhodopsin inhibit neurons, while ____rhodopsin excite neurons

Answer 30

halo; channel

Question 31

Pros of optogenetics

Answer 31

Fast temporal resolution allows real-time manipulation of brain circuits

Question 32

Cons of optogenetics

Answer 32

Implanted optic fiber does damage, and directing light into the brain causes heating which can potentially damage the tissue