Brain Rhythms and Sleep

Question 1

What is an EEG?

Answer 1

It measures the activity of a large population of neurons
Measures voltage generated by currents flowing during synaptic excitation of dendrites of many pyramidal neurons, which are activated together
The amplitude of the EEG depends on how synchronous the activity of the underlying neurons is

Question 2

What are the types of rhythms in sleep?

Answer 2

Awake- alpha rhythms and beta rhythms
REM sleep- beta rhythms
Stage 1 non-rem sleep with theta rhythms
Stage 2 non-rem sleep with spindle and K complex
Stage 3 and stage 4 non-rem sleep with delta rhythms

Question 3

What does awake and REM sleep look like?

Answer 3

High frequency, low amplitude waves
Cortical activity high and unsynchronized

Question 4

What do stages 1 and 4 look like?

Answer 4

Low frequency, high amplitude

Question 5

How do you generate synchronous brain rhythms?

Answer 5

1. Neurons take timing cues from a central pacemaker neuron
2. Synchronous timing arises from the collective behavior of all the cortical neurons (mutually exciting and inhibiting one another)

Question 6

What is epilepsy?

Answer 6

A condition where a person experiences repeated seizures
Upset in the balance of synaptic excitation and inhibition

Question 7

What is non-REM sleep?

Answer 7

Period of rest
Muscle tension reduced
Increased parasympathetic tone: heart rate slow down
Digestive processes speed up
Slow firing rates of neurons

Question 8

What is REM sleep?

Answer 8

Dreaming sleep
Atonia, total loss of muscle tone
Paralysis- incapable of moving
Rapid Eye Movements (REM)
Increased sympathetic tone, increased and irregular heart rate and respiration rates

Question 9

What are ultradian rhythms?

Answer 9

Cycles that repeat less than a 24-hour cycle
Ex. sleep

Question 10

What is the sleep cycle?

Answer 10

Stage 1: transitional sleep
Stage 2: slightly deeper sleep
sleep spindles
Stage 3: Eye and body movements are few
Stage 4: deepest stage

Question 11

Why do we sleep?

Answer 11

Memory consolidation

Question 12

What is orexin?

Answer 12

Secreting neurons in the lateral hypothalamus
Promotes wakefulness
Inhibits REM
Loss of orexin neurons leads to a sleep disorder called narcolepsy

Question 13

What is the Ascending Reticular Activating System (ARAS)?

Question 14

What is the Ventrolateral Preoptic Area of Hypothalamus (VPLO)?