scholarly journals Metabolic rate in common shrews is unaffected by temperature, leading to lower energetic costs through seasonal size reduction

2020 ◽  
Vol 7 (4) ◽  
pp. 191989
Author(s):  
Paul J. Schaeffer ◽  
M. Teague O'Mara ◽  
Japhet Breiholz ◽  
Lara Keicher ◽  
Javier Lázaro ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Energy Savings ◽  
Common Shrew ◽  
Cold Temperatures ◽  
Ambient Temperatures ◽  
Main Driver ◽  
Absolute Energy ◽  
The Common ◽  
The Brain ◽  
Harsh Conditions

Small endothermic mammals have high metabolisms, particularly at cold temperatures. In the light of this, some species have evolved a seemingly illogical strategy: they reduce the size of the brain and several organs to become even smaller in winter. To test how this morphological strategy affects energy consumption across seasonally shifting ambient temperatures, we measured oxygen consumption and behaviour in the three seasonal phenotypes of the common shrew ( Sorex araneus ), which differ in size by about 20%. Body mass was the main driver of oxygen consumption, not the reduction of metabolically expensive brain mass. Against our expectations, we found no change in relative oxygen consumption with low ambient temperature. Thus, smaller body size in winter resulted in significant absolute energy savings. This finding could only partly be explained by an increase of lower cost behaviours in the activity budgets. Our findings highlight that these shrews manage to avoid one of the most fundamental and intuitive rules of ecology, allowing them to subsist with lower resource availability and successfully survive the harsh conditions of winter.

Seasonal Changes in the Brain-case of the Common Shrew (Sorex araneus L.)

Nature ◽  
1959 ◽  
Vol 183 (4665) ◽  
pp. 907-908 ◽  
Author(s):  
PETER CROWCROFT ◽  
JEAN M. INGLES
Keyword(s):  
Seasonal Changes ◽  
Common Shrew ◽  
Sorex Araneus ◽  
The Common ◽  
Common Shrew Sorex Araneus ◽  
The Brain

scholarly journals THE ONTOGENY OF SHIVERING THERMOGENESIS IN THE RED-WINGED BLACKBIRD (AGELAIUS PHOENICEUS)

1994 ◽  
Vol 191 (1) ◽  
pp. 59-88 ◽  
Author(s):  
J Olson
Keyword(s):  
Oxygen Consumption ◽  
Agelaius Phoeniceus ◽  
Threshold Temperature ◽  
Emg Activity ◽  
Metabolic Rates ◽  
Ontogenetic Changes ◽  
Experimental Conditions ◽  
Cold Temperatures ◽  
Ambient Temperatures ◽  
Shivering Thermogenesis

The ontogeny of shivering thermogenesis was investigated in the altricial red-winged blackbird (Agelaius phoeniceus). Two indices of heat production ­ the rate of oxygen consumption (V(dot)O2) of the bird and the electromyographic (EMG) activity of the pectoralis (PECT) and gastrocnemius (GAST) muscles ­ were measured simultaneously in adult and nestling red-winged blackbirds as they were subjected first to thermoneutral temperatures and subsequently to progressively colder ambient temperatures (Ta). The ontogenetic changes in both indices indicated that the capability for thermogenesis in nestling red-winged blackbirds improved markedly with age. The metabolic rates of 3-day-old nestlings decreased during exposure to gradually falling ambient temperatures; at best, these nestlings were only able to maintain mass-specific V(dot)O2 at levels similar to or slightly above the resting metabolic rate at thermoneutral temperatures (RMR) for a short time before metabolic rates decreased with further cooling. Shivering was detected only in the PECT muscles and was of a relatively low intensity (maximum of sevenfold increase in intensity over basal levels). The 5-day-old nestlings increased mass-specific V(dot)O2 modestly (approximately 1.4-fold) above RMR and attained slightly higher maximal factorial increases in the EMG activity of the PECT (maximum of 18-fold basal levels) when exposed to the same experimental conditions. Shivering was also detected in the GAST muscles of these birds. The most striking improvements in both measures observed during the nestling period occurred between day 5 and day 8. Eight-day-old nestlings increased metabolic rates by approximately 2- to 2.5-fold over basal levels and sustained these elevated rates for longer before becoming hypothermic. Both the PECT and GAST muscles contributed significantly to shivering thermogenesis, and these older nestlings attained much higher factorial increases in the intensity of shivering (up to 72-fold) during exposure to cold temperatures. In addition, both the range and magnitude of the dominant frequencies of muscle activity in the PECT increased during postnatal development. The PECT muscles were a principal site of shivering thermogenesis in all nestling and adult red-winged blackbirds studied here. Shivering in these muscles was a 'first line defense' against cold; the threshold temperature for shivering in the PECT muscles coincided with the lower critical temperature for oxygen consumption (TLC), and the subsequent increases in EMG activity in this muscle with further cooling correlated well with the corresponding increases in mass-specific V(dot)O2.

Energy savings from vocal regulation of ambient temperature by 3-day-old domestic chicks

1996 ◽  
Vol 74 (4) ◽  
pp. 599-605 ◽  
Author(s):  
Anton Espira ◽  
Roger M. Evans
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Thermal Gradient ◽  
Energy Savings ◽  
Net Energy ◽  
Natural Conditions ◽  
Ambient Temperatures ◽  
Domestic Chicks ◽  
Important Means ◽  
Cold Challenge

Precocial domestic chicks (Gallus domesticus) become endothermic at or soon after hatching, but when chilled still vocalize to solicit heat from a parent or surrogate. In this study, we examined the potential energy savings resulting from vocal solicitation of heat by comparing the oxygen consumption of 3-day-old chicks facing a cold challenge of 20 °C with and without the option of regulating ambient temperature by vocally soliciting 2-min periods of rewarming at 35 °C from a surrogate parent in the laboratory. Body temperature was unaffected by vocal regulation, but the thermal gradient between body and ambient temperature was reduced by 5.0 ± 0.4 °C (mean ± SE). Mass-specific oxygen consumption [Formula: see text] increased by 62.5% to a near steady state mean of 3.64 mL∙g−1∙h−1 during constant chilling at 20 °C, but increased by only 48.1%, to 3.08 mL∙g−1∙h−1, during vocal regulation. Relative to chilled controls, vocally regulating chicks had a mean net energy saving of 15.4% during the final, stable 15 min of testing. Vocal solicitation of heat from a brooding parent seems likely to be an important means of saving energy expended in thermoregulation in some precocial species when young chicks are exposed to low ambient temperatures under natural conditions.

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

Measuring the World

2018 ◽  
Author(s):  
Ann-Sophie Barwich
Keyword(s):  
Sensory Information ◽  
Network Models ◽  
Model System ◽  
Stimulus Input ◽  
Expectancy Effects ◽  
Neural Network Models ◽  
Perceptual Object ◽  
External Objects ◽  
The Common ◽  
The Brain

How much does stimulus input shape perception? The common-sense view is that our perceptions are representations of objects and their features and that the stimulus structures the perceptual object. The problem for this view concerns perceptual biases as responsible for distortions and the subjectivity of perceptual experience. These biases are increasingly studied as constitutive factors of brain processes in recent neuroscience. In neural network models the brain is said to cope with the plethora of sensory information by predicting stimulus regularities on the basis of previous experiences. Drawing on this development, this chapter analyses perceptions as processes. Looking at olfaction as a model system, it argues for the need to abandon a stimulus-centred perspective, where smells are thought of as stable percepts, computationally linked to external objects such as odorous molecules. Perception here is presented as a measure of changing signal ratios in an environment informed by expectancy effects from top-down processes.

The Dioptrique

2017 ◽  
Author(s):  
Walter Ott
Keyword(s):  
Sensory Experience ◽  
The Other ◽  
Brain Image ◽  
Brain Motion ◽  
Natural Geometry ◽  
The Common ◽  
The Brain

Descartes’s treatment of perception in the Optics, though published before the Meditations, contains a distinct account of sensory experience. The end of the chapter suggests some reasons for this oddity, but that the two accounts are distinct is difficult to deny. Descartes in the present work topples the brain image from its throne. In its place, we have two mechanisms, one purely causal, the other inferential. Where the proper sensibles are concerned, the ordination of nature suffices to explain why a given sensation is triggered on the occasion of a given brain motion. The same is true with regard to the common sensibles. But on top of this purely causal story, Descartes re-introduces his doctrine of natural geometry.

scholarly journals Correlates of reproductive success within alternative mating tactics of the common shrew

1996 ◽  
Vol 7 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Paula Stockley ◽  
Jeremy B. Searle ◽  
David W. Macdonald ◽  
Catherine S. Jones
Keyword(s):  
Reproductive Success ◽  
Common Shrew ◽  
Alternative Mating Tactics ◽  
Mating Tactics ◽  
The Common

scholarly journals Extending the extended consciousness debate: perception, imagination, and the common kind assumption

2021 ◽  
Author(s):  
James Deery
Keyword(s):  
Perceptual Experience ◽  
Phenomenal Consciousness ◽  
Psychological Theory ◽  
Predictive Processing ◽  
Mental Event ◽  
The World ◽  
Predictive Approach ◽  
The Common ◽  
The Relationship ◽  
The Brain

AbstractFor some, the states and processes involved in the realisation of phenomenal consciousness are not confined to within the organismic boundaries of the experiencing subject. Instead, the sub-personal basis of perceptual experience can, and does, extend beyond the brain and body to implicate environmental elements through one’s interaction with the world. These claims are met by proponents of predictive processing, who propose that perception and imagination should be understood as a product of the same internal mechanisms. On this view, as visually imagining is not considered to be world-involving, it is assumed that world-involvement must not be essential for perception, and thus internalism about the sub-personal basis is true. However, the argument for internalism from the unity of perception and imagination relies for its strength on a questionable conception of the relationship between the two experiential states. I argue that proponents of the predictive approach are guilty of harbouring an implicit commitment to the common kind assumption which does not follow trivially from their framework. That is, the assumption that perception and imagination are of the same fundamental kind of mental event. I will argue that there are plausible alternative ways of conceiving of this relationship without drawing internalist metaphysical conclusions from their psychological theory. Thus, the internalist owes the debate clarification of this relationship and further argumentation to secure their position.

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