Behavioral Neuroscience, lecture on Afferent Path and SCN
USD Department of Biology
Behavioral Neuroscience
Rhythmicity & Behavior
Sensory input for Rhythmicity
Afferent path to the SCN
Figures of Rhythmicity
Molecular mechanisms of Circadian Rhythms Circadian Rhythms
Efferent SCN output
Integration of Rhythms into Behavior
Molecular SCN
end  Acronyms/Abbreviations   Syllabus
Pictures of Oscillation:
Sine wave:


Two identical waves out of phase
out of phase

In Phase - Phase Shifting:
in phase

Phase Angle between 2 waves with different amplitude
phase angle difference

Phase Angle compututation
phase angle computation

Biological Oscillations:
(1) per gene expression
per gene expression

(2) Sleep/Wake cycles - Alertness Sleep/Wake Cycles - Alertness

Examples of Natural Biological Rhythms:

1) Circannual weight rhythm in ground squirrels

2) Clock of human rhythms
the Brain from Top to Bottom
3) Body Temperature (Tob) Rhythms

4) Hormone rhythms

5) Rhythms of Alertness

Rhythms from Multiple Oscillators
1)Brain Regions 2)Peripheral Tissues

3) Human Physiological Rhythms

Activity Rhythms
1) Cave Experiment
For the first 9 days of this experiment, the subject was exposed to the natural variations in ambient light and noises that characterize day and night. The first 9 lines of the diagram thus represent the control records for this experiment. For the next 25 days, the subject was cut off from all such cues as to the time of day and was left to operate according to his own endogenous rhythm. He continued to display a sleep-wake cycle, but it lengthened to about 25 hours. (After several weeks of such isolation, these cycles may get even longer—30 to 36 hours. For instance, a subject may stay awake for 20 hours, then sleep for 12, and feel completely fine.)
2) Wheel Running
Wheel running rhythms after degraded Per and Cry
Wheel running rhythms after degraded Per and Cry effects
tau mutation on CK1e gene: heterozygous 22 h cycle; homozygous 20 h cycle
CK1e necessary to phosphorylate and inactivate PER
Afh mutation in Fbxl3 gene, which degrades CRY protein