Lecture 9 - neuronal oscillations

Question 1

What are neuronal oscillations?

Answer 1

the rhythmic or repetitive patterns of neural activity in the CNS

Question 2

What is an MEG and what does it measure?

Answer 2

• magnetoencephalogram
• measures the magnetic field rather than electrical field

Question 3

What does an MEG do in terms of temporal and spatial resolution?

Answer 3

keeps temporal resolution but improves spatial resolution

Question 4

What type of oscillation frequency and amplitude is seen when there is active sensory processing, attention and memory active?

Answer 4

• low amplitude, high frequency
• small and fast

Question 5

What type of oscillation frequency and amplitude is seen when there is inactive quiescence and sleep?

Answer 5

• high amplitude, low frequency
• big and slow

Question 6

What are theta oscillations?

Answer 6

increased theta (4-8Hz) in the hippocampus

Question 7

When do theta oscillations occur?

Answer 7

during goal-directed navigation but not during aimless movement.

Question 8

What experiment/task showed the increased theta oscillations?

Answer 8

• MEG study with a virtual water maze task
• using a joystick to navigate to a hidden platform

Question 9

What does the local field potential reflect?

Answer 9

the average behaviour of a large number of interacting neurons.

Question 10

What channel responds to blue light (optogenetics)?

Answer 10

• ChR2 channel lets positive charge in, depolarising the cell.

Question 11

What channel responds to yellow light (optogenetics)?

Answer 11

• NpHR halorhodopsin is a Cl- channel.
• Hyperpolarises the cell and stops it from firing.

Question 12

How do basket cells produce rhythm?

Answer 12

-inhibitory
- fast spiking
- 200-300Hz
- identified by calcium binding protein parvalbumin

Question 13

How does GABA inhibition produce rhythm?

Answer 13

• interneurons depolarised, coupled together = slow firing as one neuron inhibited by the other
• interneurons depolarised, not coupled together = fast firing

Question 14

When is beta-gamma coupling increased in the entorhinal cortex-hippocampus?

Answer 14

during a learning task

Question 15

How does the brain conduct and learn different tasks?

Answer 15

oscillations synchronising activity across regions and groups

Question 16

Name 3 diseases that deficits in gamma activity is linked too.

Answer 16

1. Alzheimer’s
2. Schizophrenia
3. Autism

Question 17

Describe abnormal parvalbumin interneurons.

Answer 17

• Nav 1.1 is a sodium channel expressed on PV interneurons.
• Decreased Nav 1.1 expression suggests decreased PV interneurons.

Question 18

What does restored Nav 1.1 function lead to?

Answer 18

• increased interneuron activity
• increased gamma activity
• increased memory function
• decreased hyper synchrony

Question 19

What could indicate activity-dependent GABA dysfunction on an EEG?

Answer 19

decreased spontaneous IPSCs

Question 20

What does stimulating the brain at gamma frequency activity do?

Answer 20

reduces the levels of beta amyloid pathology
re-sets the E-I balance and prevents disease progression

Question 21

What are the stages of sleep?

Answer 21

1. light sleep - stage 1 and 2
2. slow wave sleep (SWS) - stage 3 and 4
3. rapid eye movement sleep (REM) and non-REM

Question 22

Describe the 2-phase consolidation period.

Answer 22

• during consolidation newly encoded memory traces are reactivated in the fast learning store.
• this drives the slow learning store.
• representations in the slow learning store are gradually strengthened.

Question 23

What does boosting oscillations during sleep do?

Answer 23

potentiates declarative memory performance