Rhythms

Question 1

What is rhythm?

Answer 1

A cyclical process that repeats over time.

Question 2

What are the 4 ways to describe rhythm patterns?

Answer 2

1. Shape of the wave (on/off switch or smooth)
2. Amplitude (strength)
3. Frequency (intensity/ pattern repetition)
4. Phase (lag) (same frequency/amplitude but off-set in time)

Question 3

What are some basic functions rhythms are involved in?

Answer 3

heart rate
breathing
sleep
hunger

Question 4

Rhythmic processes can be measured by _____ and _____. The waves are generally categorised into __________ bands.

• _______ (4-8 Hz)
• _______ (8-13 Hz)
• _______ (40-100 Hz)
• _______ (.5-5 Hz)
• _______ (13-30 Hz)

Very easy to determine the wave form - just count the _____!

Answer 4

EEG
MEG
frequency

Theta
Alpha/Mu
Gamma
Delta
Beta

Peaks

Question 5

Functions of Rhythms

For sleep, a general rule of thumb is:

• ____ frequency, _____ amplitude rhythms are indicative of waking, alertness and dreaming.
• ____ frequency, _____ amplitude rhythms are indicative of non-dreaming sleep (and coma/vegetative state)

Answer 5

behaviour
high
low
low
high

Question 6

Functions of Rhythms

Wakefulnes/sleep transition is _____ switch. First there is wakeful relaxation with closed eyes. The predominant wave type involved is ______. In fact, this wave is suppressed when eyes are ______.

After sleep, there is an increase in low-frequency _____ waves, as well as lack of _____ and _______ movement.

Answer 6

on/off switch
open

delta
eye
muscle

Question 7

Functions of Rhythms

Waves may also be involved in experiencing a coherent world through ______ _______. This is where rhythms act like a ____ to bind things together. So neurons _______ to the same object _______.

Eg: see a red ball moving - MT (motion) and V4 (colour) and inferior temporal (objects)

Answer 7

neural synchrony
glue
reponding
synchronise

Question 8

Functions of Rhythms

Describe the evidence found for neural synchrony

Answer 8

Evidence for this was found when participants had to attend to one of two striped balls. They found that IT and V4 synchronised for the attended ball and separately for the unattended ball.

So IT is communicating with V4.

Question 9

Functions of Rhythms

Rhythmic core functions are breathing and heart rate. Describe the brain area involved, its mechanism and flexibility.

How does this relate to holding your breath? What do free divers do to cheat the system?

Answer 9

The medulla oblongata. This detects CO2 levels in the bloodstream and determines changes that need to be made. It can then also send nerve impulses to the heart and diaphragm.

It is flexible to changing conditions such as exercise. During exercise, need for O2 goes up, so medulla upregulates HR and respiration.

The medulla will override any top-down approach to holding your breath. But free divers hyperventilate. which lowers CO2 levels, and suppress reflex to breathe.

Question 10

Rhythms that are out of control can be seen in _______. Seizures occur when there is too much _______ or ________. It is better thought of as a ______ rather than a disease as they can arise from a multitude of things. It is very dangerous because of the ______ wiring of connections.

Answer 10

epilepsy
excitation
inhibition
symptom
tight

Question 11

Biorhythms - Circadian

Nearly all animals coordinate ________ according to ________ rhythms (light and dark cycles), including eating, sleeping, mating.

In the morning, the brain increases body _____, memory and ________. We have reached our peak by ________. In a typical day, our desire to sleep is greatest between _______. Then there is another period of _______ before slowing down at night.

Another interesting study related to this is flowers that open and close. Flowers kept in the dark ______ in a cyclical pattern, demonstrating that it was not the ____ but a ______ controlling this process.

Answer 11

behaviour
circadian
temperature
alertness
mid-morning
2-4pm
alertness

opened
sun
clock

Question 12

Sleep and wake have _______ inhibition. It is a _______ process. So sleep ______ wake and wake ______ sleep.

Answer 12

mutual
competitive
inhibits
inhibits

Question 13

What is running these brain rhythms? The “master clock”? What is the evidence for this?

Answer 13

Suprachiasmatic nucleus (SCN)

• activity correlated with circadian rhythms (high in day, low at night)
• lesions abolished rhythms
• isolated SCN continued to cycle (it doesn’t need any input - does it all itself)
• transplanted SCN imparts rthythm of the donor

Question 14

The SCN has quite a long cycle of ______ hours. It is reset everyday by photosensitive retinal _______ cells.

Answer 14

24-25 hours

ganglion