April 17, 2009

The Emergence of Consciousness in Phylogeny

comparative studies,evolution — alice @ 12:00 am

Michel Cabanac, Arnaud J. Cabanac, Andre Parent
Article in Behavioural Brain Research

Abstract
The brains of animals show chemical, anatomical, and functional differences, such as dopamine production and structure of sleep, between Amniota and older groups. In addition, play behavior, capacity to acquire taste aversion, sensory pleasure in decision making, and expression of emotional tachycardia and fever started also to be displayed by Amniota, suggesting that the brain may have began to work differently in early Amniota than in Lissamphibia and earlier vertebrates. Thus we propose that emotion, and more broadly speaking consciousness, emerged in the evolutionary line among the early Amniota. We also propose that consciousness is characterized by a common mental pathway that uses pleasure, or its counterpart displeasure, as a means to optimize behavior.

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December 11, 2007

The trivial function of sleep

Rest in poikilothermic animals is an adaptation of the organism to adjust to the geophysical cycles, a doubtless valuable function for all animals. In this review, we argue that the function of sleep could be trivial for mammals and birds because sleep does not provide additional advantages over simple rest. This conclusion can be reached by using the null hypothesis and parsimony arguments.

First, we develop some theoretical and empirical considerations supporting the absence of specific effects after sleep deprivation. Then, we question the adaptive value of sleep traits by using non-coding DNA as a metaphor that shows that the complexity in the design is not a definitive proof of adaptation.

We then propose that few, if any, phenotypic selectable traits do exist in sleep. Instead, the selection of efficient waking has been the major determinant of the most significant aspects in sleep structure. In addition, we suggest that the regulation of sleep is only a mechanism to enforce rest, a state that was challenged after the development of homeothermy.

As a general conclusion, there is no direct answer to the problem of why we sleep; only an explanation of why such a complex set of mechanisms is used to perform what seems to be a simple function. This explanation should be reached by following the evolution of wakefulness rather than that of sleep. Sleep could have additional functions secondarily added to the trivial one, although, in this case, the necessity and sufficiency of these sleep functions should be demonstrated.

The trivial function of sleep. R.V. Rial, Maria C. Nicolau, Antoni Gamundi, Mourad Akaarir, Sara Aparicio, Celia Garau, Silvia Tejada, Catalina Roca, Lluis Gene, David Moranta, Susana Esteban, 2007. Sleep Medicine Reviews 11(4):311-325.

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September 15, 2007

Brain stem may be key to consciousness:

From MindHacks
An article in this week’s Science News discusses whether the brain stem may play a more central role in consciousness than it’s usually given credit for.

It focuses on children with hydranencephaly, a where the cortex fails to develop in children and instead, the space is filled with cerebral spinal fluid.

Typically, affected children survive only a few months after birth, but those that do survive seem to remarkably more conscious than you would guess based on theories that suggest the cortex is where all the action happens to support consciousness.

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September 12, 2007

Gorillas heads race to extinction

animal minds,comparative studies — thomasr @ 2:07 pm

According to the Red List of Threatened Species for 2007, gorillas, orangutans, and corals are among the plants and animals which are sliding closer to extinction. You can read more about this at BBC.

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June 15, 2007

Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations

attention.jpgAttention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention.

Science

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January 17, 2007

Jane Goodall Podcast

goodall_461.jpgABC Radio National in Australia has an excellent podcast on a talk by Jane Goodall , an English primatologist, ethologist and anthropologist, who is well known for conducting a forty-five year study of chimpanzee social and family life.

In her talk, Goodall addresses the issue of animal personality and animal minds. It is a powerful reminder of how much this issue has been a scientific taboo for not too long ago.

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December 29, 2006

The effort-decision brain circuitry

comparative studies,decision making — thomasr @ 12:32 pm

What are the brain areas responsible for decision making? And is there a difference between easy and hard decisions? In an article in Cerebral Cortex, researchers find that amygdala and prefrontal cortex form an interconnected neural circuit that may mediate effortful decision-making.  Click through for abstract. HubMed.

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