oscillation and memory

Question 1

3 reasons why we sleep

Answer 1

Cut off from external stimuli:
important information to be retained
useless information to be forgotten
conservation of energy
clearning of unwanted metabolites by glymphatic system

Question 2

what type of sleeping pattern do humans exhibit?

Answer 2

Diurnal : awake during the day, sleep at night

Question 3

Describe sleeping pattern of metaturnal animals

Answer 3

Sleep partly at day, partly at night eg cats and rabbits

Question 4

How many stages of sleep are there?

Answer 4

5

Question 5

During exploration, which waves are most prominent?

Answer 5

Theta waves 5-12 Hz in the CA1 region of hippocampus

Cells have a preferential firing area-place field

Question 6

Describe NREM characteristic transient waves

Answer 6

transient waves involving 1. slow wave part
2. ripple part
slow wave and ripple parts comprise sharp wave ripples 50-100 ms

Question 7

True/False. The same set of neurons from exploration get reactivated in NREM sleep but only in a time compressed manner

Answer 7

True. This stengthens action between synapses

Question 8

Define sharp wave ripples

Answer 8

Rapid, depolarizing events generated in CA3 and propagated to CA1 where ripples (100-300 Hz) high frequency oscillatory activity originates

Question 9

At what stage of sleep do theta transition into sleep spindles and K complex

Answer 9

Deep sleep

Question 10

Random saw tooth like waves can be seen at what stage of sleep

Answer 10

REM

Question 11

Define the cell assembly theory

Answer 11

Hebb’s postulatte: neuronal connections are strengthened by repeated synchronous activity during behavior which leads to formation of an assembly

Question 12

Components of a sharp wave ripple (recorded from CA1)

Answer 12

Ripples band - 100 to 400 Hz

Slow wave ripple 1 to 5 Hz

Question 13

3 in vivo recording methods

Answer 13

Tetrodes, silicone probe, neuropixel probes

Disadvantage: Everything is blind, location is determined after the recording

Question 14

What gives rise to field potential signals?

Answer 14

Stimulations of neural oscillations at 10 Hz

Question 15

Mechanisms of oscillations

Answer 15

Pacemaker oscillation:circadian rhythm, heart beat, sleep spindles, hippocampal, medial septum and EC oscillations
Emergent oscillation: hippocampal gamma, hippocampal sharp wave

Question 16

3 classes of interneurons invloved in theta and sharp wave ripples

Answer 16

1. Parvalbumin +ve basket cells, target soma, fire at trough of theta
2. Axo axonic PV +ve target axon, fire after peak
3. OLM cellls-target apical dendrite, fire at trough

Question 17

Mechanisms of sharp wave ripple generation

Answer 17

Gap junctions between pyramidal cells
Feedback inhibition
Reciprocol inhibition
Feedback and Reciprocol inhibition

Question 18

What is the waxing and waning of field potentials at 7-14 Hz

Answer 18

Sleep spindles

Question 19

Hippocampal ripples occur in the down up transitions in the cortex. True/False

Answer 19

True

Question 20

Theories of memory consolidation

Answer 20

1.REM sleep in memory consolidation
theta during REM sleep is needed for learning
2. NREM sleep: 2 stage model, SWRs disruption learning is impaired
3. Sequential hypothesis: both REM and NREM important

Question 21

2 stage model of memory consolidation

Answer 21

Exploration- in4 deposited in liable form
During SWS liable trace is converted into long-lasting form
High freq firing of ensambles of neurons associated with previous learnign experience promote LTP

Question 22

Where do we see bimodal distribution of membrane potential?

Answer 22

Entorhinal Cortex. Hippo is unimodal