Chapter 16 - Brain Rythms And Sleep Flashcards
What does the alplitude of the EEG depend on?
I’m how synchronous the activity of the underlying neurons is
What state is associated with low amplitude high frequency waves?
What can you say about the cortical activity?
Awake or dreaming stages of sleep.
Cortical activity is high and unsynchronized
What state is associated with high amplitude low frequency waves?
What can you say about the cortical activity?
Non-dreaming sleep states or coma.
- Cortical neurons are not engaged in information processing.
- large numbers of neurons excited by common slow rhythmic input
How is the generation of synchronous brain rhythms initiated?
By a central pacemaker neuron.
Synchronous timing arises from the collective behavior of all the cortical neurons
Explain what the two-neuron oscillator does and how
Constantly active excitatory input excited E cell, which excites I cell which inhibits E cell and so forth
It’s responsible for rhythmic activity
What are the two mechanisms that generate synchronous brain rhythms?
1) two neuron oscillator
2) thalami pacemaker neuron (chef d’orchestre)
What drives rhythmic activity in the cortex? How does it work?
Rhythmic activity in the thalamus
Synaptic connections between excitatory and inhibitory neurons force each neuron to conform to the rhythm of the group
What are the 3 functional states of the brain? Define each one
1) awake: EEG low voltage and fast
2) REM sleep
- EEG looks like you’re awake
- Body immobilize
- Dreams
3) non-REM sleep
- EEG high voltage and slow
- 4 stages
What can you say about parasympathetic tone, firing rates of neurons and amplitude of EEG during non-REM sleep?
- Increased parasympathetic tone: heart rate, respiration, kidney function slow down
- slow firing rates of neurons
- slow, large amplitude of EEG- neurons firing synchronously
What can you say about sympathetic tone, firing rates of neurons and amplitude of EEG during REM sleep?
- EEG almost indistinguishable from waking, fast, low voltage
- rapid eye movement
- increased sympathetic tone, increased and irregular heart rate and respiration rate
What are ultradian rhythms?
Cycles repeated throughout a 24 hour circadian day
- cycle every 90 min
- REM 25%
- Non-REM 75%
What are the 4 stages of non-REM sleep? Define each one
Stage 1:
- transitional sleep
- lasts only a few minutes
Stage 2:
- slightly deeper sleep
- lasts 5-15 minutes
- sleep spindles (hi freq, low amplitude)
- generated by the thalamic pacemaker
- K complexes
Stage 3:
- eye and body movements are few
Stage 4:
- deepest stage large EEG rhythms
Why do we sleep?
- verbal learning
- spatial learning
- sensori-motrice learning
What controls the sleep and waking?
Diffuse modulatory neurotransmitter systems
What happens during waking, which enhances awake state?
Locus coeruleus
