Dolphins maintain cognitive performance during 72 to 120 hours of continuous auditory vigilance

Ridgway, Sam H.; Keogh, Mandy; Carder, Donald A.; Finneran, James J.; Kamolnick, Tricia; Todd, Mark; Goldblatt, Allen

doi:10.1242/jeb.027896

Cited by 37 publications

(34 citation statements)

References 39 publications

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“…The right side is always larger (Mead, 1975). The preponderance of observations show that dolphins make pulsed sounds on the right side of the nose and whistles on the left (Ridgway et al, 2009;Madsen et al, 2013). Cranford et al…”

Section: Discussionmentioning

confidence: 99%

“…Researchers have previously found that unihemispheric sleep includes the corticothalamic areas of the brain (Ladygina and Supin, 1977;Supin et al, 1978). Furthermore, the studies of Branstetter et al (2012) and Ridgway et al (2006Ridgway et al ( , 2009 demonstrated that dolphins might be able to respond to echoes or to presented tones continuously, despite the necessity for sleep. They get essential sleep critical for homeostasis and for maintaining awareness by engaging in unihemispheric sleep.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, when we wish to train a dolphin to respond with a whistle, we tap the left side of the blowhole. For pulsed sound, we tap the right side (Ridgway et al, 2009). We have never tried to train the dolphin to reverse sides with their sounds; however, Cranford et al (2011) showed that minorities of observed pulsed sounds were on the left.…”

Section: Introductionmentioning

confidence: 99%

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On doing two things at once: dolphin brain and nose coordinate sonar clicks, buzzes, and emotional squeals with social sounds during fish capture

Ridgway

Dibble

Alstyne

et al. 2015

Journal of Experimental Biology

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Dolphins fishing alone in open waters may whistle without interrupting their sonar clicks as they find and eat or reject fish. Our study is the first to match sound and video from the dolphin with sound and video from near the fish. During search and capture of fish, free-swimming dolphins carried cameras to record video and sound. A hydrophone in the far field near the fish also recorded sound. From these two perspectives, we studied the time course of dolphin sound production during fish capture. Our observations identify the instant of fish capture. There are three consistent acoustic phases: sonar clicks locate the fish; about 0.4 s before capture, the dolphin clicks become more rapid to form a second phase, the terminal buzz; at or just before capture, the buzz turns to an emotional squeal (the victory squeal), which may last 0.2 to 20 s after capture. The squeals are pulse bursts that vary in duration, peak frequency and amplitude. The victory squeal may be a reflection of emotion triggered by brain dopamine release. It may also affect prey to ease capture and/or it may be a way to communicate the presence of food to other dolphins. Dolphins also use whistles as communication or social sounds. Whistling during sonar clicking suggests that dolphins may be adept at doing two things at once. We know that dolphin brain hemispheres may sleep independently. Our results suggest that the two dolphin brain hemispheres may also act independently in communication.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On doing two things at once: dolphin brain and nose coordinate sonar clicks, buzzes, and emotional squeals with social sounds during fish capture

Ridgway

Dibble

Alstyne

et al. 2015

Journal of Experimental Biology

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“…An increased number of glial cells in the cetacean brain, as seen herein when compared to artiodactyls, may result in an increased production of lactate. This extracellular lactate may be related to maintained arousal and attention during unihemispheric sleep (Ridgway et al, 2006(Ridgway et al, , 2009Branstetter et al, 2012), as extracellular lactate concentrations are higher during periods of wake (Pellerin and Magistretti, 1994). Furthermore lactate reduces extracellular pH levels and this is vital for arousal and attention, as orexinergic neurons are excited by a low pH (Williams et al, 2007;Parsons and Hirasawa, 2010).…”

Section: Orexinergic Bouton and Glial Cell Density Interaction In Thementioning

confidence: 99%

“…Additionally, it has been demonstrated that dolphins can continuously maintain vigilant behaviour for at least 15 days without any signs of sleep deprivation (Ridgway et al, 2006(Ridgway et al, , 2009Branstetter et al, 2012), an observation not made, but unlikely to be present in artiodactyls.…”

Section: Introductionmentioning

confidence: 99%

Orexinergic bouton density is lower in the cerebral cortex of cetaceans compared to artiodactyls

Dell

Spocter

Patzke

et al. 2015

Journal of Chemical Neuroanatomy

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Highlights• The orexinergic innervation of the cerebral cortex of Cetartiodactyla is described.• All species show a similar innervation pattern.• The density of innervation is far less in cetaceans than artiodactyls. 1 AbstractThe species of the cetacean and artiodactyl suborders, which make up the cetartiodactyl order, have very different arousal thresholds and sleep-wake systems.The aim of this study was to determine whether cetaceans or artiodactyls have differently organized orexinergic arousal systems by examining the density of orexinergic innervation to the cerebral cortex. This study provides a comparison of orexinergic bouton density in the cerebral cortex of twelve cetartiodactyl species by means of immunohistochemical staining and stereological analysis. It was observed that the morphology of the axonal projections of the orexinergic system to the cerebral cortex was similar across all species, as the presence, size and proportion of large and small orexinergic boutons were similar. Despite this, orexinergic bouton density was lower in the cerebral cortex of cetaceans compared to artiodactyls, even when corrected for brain mass, neuron density, glial density and glial: neuron ratio. Glial density was identified as the major determinant for the observed differences. It appears a synergy exists between the orexinergic neurons and their projections, glial cells, and the biochemical correlates of appetitive drive and arousal, but further studies need to be performed to understand the full extent of the orexinergic system and its role in sustained arousal.

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Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts

Racicot

Colbert

2013

The Anatomical Record

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Evolution of endocranial anatomy in cetaceans is important from the perspective of echolocation ability, intelligence, social structure, and alternate pathways for circulation to the brain. Apart from the importance of studying brain shape and asymmetries as they relate to aspects of behavior and intelligence, cranial endocasts can show a close correspondence to the hydrostatic shape of the brain in life, and canals and grooves can preserve features of the circulatory system. Multiple samples are rarely available for studies of individual variation, especially in fossils, thus a first step in quantifying variation and making comparisons with fossils is made possible with CT scans of osteological specimens. This study presents a series of high-resolution X-ray CT-derived cranial endocasts of six extant species of Phocoenidae, a clade including some of the smallest and one of the rarest cetaceans. Degree of gyrification varies interspecifically and intraspecifically, possibly resulting from variation in preservation of the ossified meninges. Computed tomographic data show that visually assessed asymmetry in the cranial endocasts is not correlated with volumetric measurements, but nonetheless may reflect torsion in the skull's shape such that the right cerebral and cerebellar hemispheres extend rostrally and laterally more than the left. Vasculature and canals are similar to other described cetacean species, but the hypophyseal casts are unusual. Similarities between brain shape and volume measurements in the different species can be attributed to paedomorphism and concomitant variation in ecological preferences. This may explain similarities Neophocaena phocaenoides and Phocoena sinus share with the juvenile Phocoena phocoena specimen studied. Anat Rec,

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Dolphins maintain cognitive performance during 72 to 120 hours of continuous auditory vigilance

Abstract: SUMMARY

Cited by 37 publications

References 39 publications

On doing two things at once: dolphin brain and nose coordinate sonar clicks, buzzes, and emotional squeals with social sounds during fish capture

On doing two things at once: dolphin brain and nose coordinate sonar clicks, buzzes, and emotional squeals with social sounds during fish capture

Orexinergic bouton density is lower in the cerebral cortex of cetaceans compared to artiodactyls

Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts

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