scholarly journals The internal clock hypothesis for astro-navigation in homing pigeons

1966 ◽  
Vol 5 (7) ◽  
pp. 259-260 ◽  
Author(s):  
Merle E. Meyer
Keyword(s):  
Internal Clock ◽  
Homing Pigeons ◽  
Clock Hypothesis

An analysis of clock-shift experiments: is scatter increased and deflection reduced in clock-shifted homing pigeons?

1997 ◽  
Vol 200 (16) ◽  
pp. 2269-2277 ◽  
Author(s):  
J Chappell
Keyword(s):  
Internal Clock ◽  
Magnetic Compass ◽  
Control Group ◽  
The Sun ◽  
Visual Landmarks ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Vector Length ◽  
The Mean ◽  
Clock Shift

Clock-shifting (altering the phase of the internal clock) in homing pigeons leads to a deflection in the vanishing bearing of the clock-shifted group relative to controls. However, two unexplained phenomena are common in clock-shift experiments: the vanishing bearings of the clock-shifted group are often more scattered (with a shorter vector length) than those of the control group, and the deflection of the mean bearing of the clock-shifted group from that of the controls is often smaller than expected theoretically. Here, an analysis of 55 clock-shift experiments performed in four countries over 21 years is reported. The bearings of the clock-shifted groups were significantly more scattered than those of controls and less deflected than expected, but these effects were not significantly different at familiar and unfamiliar sites. The possible causes of the effects are discussed and evaluated with reference to this analysis and other experiments. The most likely causes appear to be conflict between the directions indicated by the sun compass and either unshifted familiar visual landmarks (at familiar sites only) or the unshifted magnetic compass (possible at both familiar and unfamiliar sites).

Pigeon homing: observations, experiments and confusions

1996 ◽  
Vol 199 (1) ◽  
pp. 21-27 ◽  
Author(s):  
C Walcott
Keyword(s):  
Release Site ◽  
Internal Clock ◽  
The Sun ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Multiple Cues ◽  
Pigeon Homing ◽  
Flight Direction ◽  
Do So

Homing pigeons can return from distant, unfamiliar release points. Experienced pigeons can do so even if they are transported anesthetized and deprived of outward journey information. Airplane tracking has shown that they make relatively straight tracks on their homeward journey; therefore, pigeons must have some way of determining the home direction at the release site. Manipulating the pigeon's internal clock causes predictable deviations in their flight direction relative to home. When the sun is not visible, such clock shifts have no effect. This result implies a two-step system: the determination of the home direction and the use of a sun compass to fly in that direction. When pigeons cannot see the sun they use a magnetic compass. The use of compass cues to select and maintain a direction of flight is well understood compared with the uncertainty surrounding the nature of the cues used to determine the home direction when pigeons are released at an unfamiliar site. Because they generally home successfully from any direction and distance from the loft, without requiring information gathered on the outward journey, it seems likely that they use some form of coordinate system. Presumably, a displaced pigeon compares the values of some factor at the release site with its remembered value at the home loft. This factor might be olfactory, it might be some feature of the earth's magnetic field or it might be something else. There is some evidence that pigeons may use several cues and that pigeons raised in different lofts under different environmental conditions may prefer to use one cue over another. I believe that it is this flexible use of multiple cues that has led to so much confusion in experiments on pigeon homing.

Sun-compass orientation in homing pigeons: compensation for different rates of change in azimuth?

2000 ◽  
Vol 203 (5) ◽  
pp. 889-894 ◽  
Author(s):  
R. Wiltschko ◽  
M. Walker ◽  
W. Wiltschko
Keyword(s):  
Internal Representation ◽  
Apparent Movement ◽  
Internal Clock ◽  
Time Of Day ◽  
The Sun ◽  
Compass Orientation ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Rates Of Change ◽  
Compensation Mechanisms

Birds using their sun compass must compensate for the apparent movement of the sun with the help of their internal clock. The movement of the sun is not uniform, being much faster around noon than near sunrise and sunset. If the sun-compass mechanisms are not adjusted to these variations, considerable errors might arise. To learn whether birds are able to take the different rates of sun azimuth change into account, we subjected homing pigeons to a 4 h fast clock-shift. The experiments were performed near Auckland, New Zealand, at a latitude of 37 degrees S, where the expected deflections for a 4 h shift in summer vary from less than 40 degrees to more than 120 degrees, depending on time of day. One group of birds was released just after sunrise or during the corresponding period in the afternoon when the expected deflections were minimal, the other group during late morning when they were maximal. The different sizes of the observed deflections - between 26 degrees and 51 degrees in the first group, and between 107 degrees and 153 degrees in the second group - clearly show that the birds' compensation mechanisms are closely tuned to the varying rates of change in sun azimuth. The results suggest that pigeons have a rather precise internal representation of the sun curve, which makes the avian sun compass a highly accurate mechanism of direction finding.

scholarly journals Interval Timing, Dopamine, and Motivation

2014 ◽  
Vol 2 (3) ◽  
pp. 379-410 ◽  
Author(s):  
Fuat Balcı
Keyword(s):  
Reward Magnitude ◽  
Dopamine Agonists ◽  
Genetic Factors ◽  
Internal Clock ◽  
Behavioral Effects ◽  
Dopamine Level ◽  
Motivational State ◽  
Rightward Shift ◽  
Clock Hypothesis ◽  
Anticipatory Behavior

The dopamine clock hypothesis suggests that the dopamine level determines the speed of the hypothetical internal clock. However, dopaminergic function has also been implicated for motivation and thus the effect of dopaminergic manipulations on timing behavior might also be independently mediated by altered motivational state. Studies that investigated the effect of motivational manipulations on peak responding are reviewed in this paper. The majority of these studies show that a higher reward magnitude leads to a leftward shift, whereas reward devaluation leads to a rightward shift in the initiation of timed anticipatory behavior, typically in the absence of an effect on the timing of response termination. Similar behavioral effects are also present in a number of studies that investigated the effect of dopamine agonists and dopamine-related genetic factors on peak responding. These results can be readily accounted for by independent modulation of decision-thresholds for the initiation and termination of timed responding.

Sex Differences in Time Production Revisited

2012 ◽  
Vol 33 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Joseph Glicksohn ◽  
Yamit Hadad
Keyword(s):  
Sex Differences ◽  
Individual Differences ◽  
Sex Difference ◽  
Absolute Error ◽  
Internal Clock ◽  
Target Duration ◽  
Log P ◽  
Men And Women ◽  
Time Production ◽  
T Score

Individual differences in time production should indicate differences in the rate of functioning of an internal clock, assuming the existence of such a clock. And sex differences in time production should reflect a difference in the rate of functioning of that clock between men and women. One way of approaching the data is to compute individual regressions of produced duration (P) on target duration (T), after log transformation, and to derive estimates for the intercept and the slope. One could investigate a sex difference by comparing these estimates for men and women; one could also contrast them by looking at mean log(P). Using such indices, we found a sex difference in time production, female participants having a relatively faster internal clock, making shorter time productions, and having a smaller exponent. The question is whether a sex difference in time production would be found using other methods for analyzing the data: (1) the P/T ratio; (2) an absolute discrepancy (|P-T|) score; and (3) an absolute error (|P-T|/T) score. For the P/T ratio, female participants have a lower mean ratio in comparison to the male participants. In contrast, the |P-T| and |P-T|/T indices seem to be seriously compromised by wide individual differences.

Interrupting the internal clock: Location break effects

2006 ◽  
Author(s):  
Marina Menez ◽  
Florente Lopez
Keyword(s):  
Internal Clock ◽  
Clock Location

On the concept of time and the "internal-clock"

1985 ◽  
Author(s):  
Madjid Mashour ◽  
Carl Rollenhagen
Keyword(s):  
Internal Clock

Navigation by homing pigeons: updated perspective

2001 ◽  
Vol 13 (1) ◽  
pp. 1-48 ◽  
Author(s):  
Hans G. Wallraff
Keyword(s):  
Homing Pigeons

Genomic perspectives on the circadian clock hypothesis of psychiatric disorders

2020 ◽  
Author(s):  
Malcolm von Schantz ◽  
Mario A. Leocadio-Miguel ◽  
Michael J. McCarthy ◽  
Sergi Papiol ◽  
Dominic Landgraf
Keyword(s):  
Circadian Clock ◽  
Psychiatric Disorders ◽  
Clock Hypothesis

So, what about the molecular clock hypothesis?

1993 ◽  
Vol 3 (6) ◽  
pp. 896-901 ◽  
Author(s):  
Wen-Hsiung Li
Keyword(s):  
Molecular Clock ◽  
Molecular Clock Hypothesis ◽  
Clock Hypothesis
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