SUBJECT

Title

Biorhythms

Type of instruction

lecture

Level

master

Faculty

Faculty of Science

Part of degree program

Biology MSc

Credits

Recommended in

Semesters 1-4

Typically offered in

Autumn/Spring semester

Course description

1. Rhythm types in living organisms. External, internal and external-internal rhythms. Importance and roles of external-internal rhythms: gating, timing of breeding, navigation, seasonality, sense of time.

2. Basic terms and notions: period, amplitude, phase, Zeitgeber, free running (circa-) rhythms, subjective day and night.

3. Characteristics of external-internal rhythms. Aschoff’s and circadian rules. Synchronization with external geophysical rhythms: phase-response curve (PRC). Human rhythms. The so called „biorhythms”.

4. The biological clock. Suprachiasmatic nuclei. Anatomical description. One or more clocks? The role of the pineal gland in birds. Groups of linked rhythms. Inputs to the suprachiasmatic nuclei and their role.

5. Generation of the circadian rhythm. Transmission of the generated rhythm to other parts of the brain and to the body.

6. Precise clock from unreliable building blocks. Enright’s theory. Implementation of the model, its functional characteristics. Reproduction of biological clock features by the model. Advancement of the model: precise clock built from damped oscillators.

7 Alternation of sleep and wakefulness as the most obvious circadian rhythm. Definitions. Changes in polygraphic signals (EEG, EMG, EOG) during sleep. Sleep stages and their ultradian rhythm.

8. Theories of sleep. Passive and active hypotheses. Activating (waking) centers. Brainstem reticular formation as the central regulator of wakefulness. The hypothetical cholinergic ascending activating pathways (ARAS).

9. Criteria for the sleep center. Suggested structures: tractus solitarius, raphe nuclei, thalamus, basal forebrain. The basal forebrain cholinergic system and its role in the maintenance of wakefulness.

10. Thalamocortical mechanisms of cortical EEG patterns. Neuronal circuitry. Ion channels and their role in the two functional states of the thalamus (relay or transmitting and bursting mode).

11. Humoral regulation of sleep. Methods and methodological obstacles in the search for sleep factors. Hypothetical sleep factors. Contradictions concerning the humoral regulation of sleep.

12. Biological functions of sleep. Sleep deprivation, consequences of total and partial prevention of sleep.

13. Interaction between the circadian and homeostatic regulations of sleep. The two-process theory and its implementation in the form of a mathematical model. Reproduction of known characteristics of the sleep-wake cycle by the model.

14. Regulation of rapid-eye-movement (REM) sleep. Theories about the functions of REM sleep. The hypothesis of receptor sensitivity regulation.

Readings

Willard L. Koukkari, Robert B. Sothern: Introducing Biological Rhythms: A Primer on the Temporal Organization of Life, with Implications for Health, Society, Reproduction, and the Natural Environment, Springer Science & Business Media, 2007, ISBN 9781402047015
Simon Green: Biological Rhythms, Sleep and Hypnosis, Palgrave Macmillan, 2011, ISBN 9780230364783