Scientific American Mind

Thinking about Calcium Waves in Astrocytes

Excerpts from Andrew Koob’s discussion of glial cells and his related book, The Root of Thought, with Jonah Lehrer in "The Root of Thought: What Do Glial Cells Do?" Scientific American (October 27, 2009):

The Root of Thought: Unlocking Glia- the Brain Cell That Will Help Us Sharpen Our Wits, Heal Injury, and Treat Brain Disease Until the last 20 years, brain scientists believed neurons communicated to each other, represented our thoughts, and that glia were kind of like stucco and mortar holding the house together.  They were considered simple insulators for neuron communication.  There are a few types of glial cells, but recently scientists have begun to focus on a particular type of glial cell called the 'astrocyte,' as they are abundant in the cortex.

Interestingly, as you go up the evolutionary ladder, astrocytes in the cortex increase in size and number, with humans having the most astrocytes and also the biggest.  Scientists have also discovered that astrocytes communicate to themselves in the cortex and are also capable of sending information to neurons. Finally, astrocytes are also the adult stem cell in the brain and control blood flow to regions of brain activity. Because of all these important properties, and since the cortex is believed responsible for higher thought, scientists have started to realize that astrocytes must contribute to thought. 

In short, calcium waves are how astrocytes communicate to themselves. Astrocytes have hundreds of 'endfeet' spreading out from their body. They look like mini octopi, and they link these endfeet with blood vessels, other astrocytes and neuronal synapses. Calcium is released from internal stores in astrocytes as they are stimulated, then calcium travels through their endfeet to other astrocytes. The term 'calcium waves' describes the calcium release and exchange between astrocytes and between astrocytes and neurons.

Glial Cells Scientists at Yale, most notably Ann H. Cornell-Bell and Steven Finkbeiner, have shown that calcium waves can spread from the point of stimulation of one astrocyte to all other astrocytes in an area hundreds of times the size of the original astrocyte (watch video).

Furthermore, calcium waves can also cause neurons to fire. And calcium waves in the cortex are leading scientists to infer that this style of communication may be conducive to the processing of certain thoughts. If that isn't convincing, it was recently shown that a molecule that stimulates the same receptors as THC can ignite astrocyte calcium release. 

This idea [that glia and their calcium waves might play a role in creativity] stems from dreams, sensory deprivation and day dreaming. Without input from our senses through neurons, how is it that we have such vivid thoughts?  How is it that when we are deep in thought we seemingly shut off everything in the environment around us? 

In this theory, neurons are tied to our muscular action and external senses. We know astrocytes monitor neurons for this information. Similarly, they can induce neurons to fire. Therefore, astrocytes modulate neuron behavior.

This could mean that calcium waves in astrocytes are our thinking mind. Neuronal activity without astrocyte processing is a simple reflex; anything more complicated might require astrocyte processing. The fact that humans have the most abundant and largest astrocytes of any animal and we are capable of creativity and imagination also lends credence to this speculation.

Calcium is also released randomly and without stimulation from astrocytes' internal stores in small bursts called 'puffs.'  These random puffs can lead to waves.  It is possible that the seemingly random thoughts during dreams and sensory deprivation experience could be calcium puffs becoming waves in our astrocytes.

Basically, it is obvious that astrocytes are involved in brain processing in the cortex, but the main questions are, do our thoughts and imagination stem from astrocytes working together with neurons, or are our thoughts and imagination solely the domain of astrocytes?  Maybe the role of neurons is to support astrocytes.

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Love and Creativity

Excerpt from “Does Falling in Love Make Us More Creative?” by Nira Liberman and Oren Shapira, Scientific American: Mind Matters (September 29, 2009):

Why does the act of falling in love—or at least thinking about love—lead to such a spur of creative productivity?

Bright Star (Ben Wishaw and Abbie Cornish)

One possibility is that when we’re in love we actually think differently. This romantic hypothesis was recently tested by the psychologists Jens Förster, Kai Epstude, and Amina Özelsel at the University of Amsterdam. The researchers found that love really does alter our thoughts, and that this profound emotion affects us in a way that is different than simply thinking about sex.

Bright Star (Ben Wishaw)

The clever experiments demonstrated that love makes us think differently in that it triggers global processing, which in turn promotes creative thinking and interferes with analytic thinking. Thinking about sex, however, has the opposite effect: it triggers local processing, which in turn promotes analytic thinking and interferes with creativity.

Bright Star (Abbie Cornish)

Why does love make us think more globally? The researchers suggest that romantic love induces a long-term perspective, whereas sexual desire induces a short-term perspective. This is because love typically entails wishes and goals of prolonged attachment with a person, whereas sexual desire is typically focused on engaging in sexual activities in the "here and now". Consistent with this idea, when the researchers asked people to imagine a romantic date or a casual sex encounter, they found that those who imagined dates imagined them as occurring farther into the future than those who imagined casual sex.

Bright Star (Abbie Cornish and Ben Wishaw)

According to construal level theory (CLT), thinking about events that are farther into the future or past—or any kind psychological distancing (such as considering things or people that are physically farther away, or considering remote, unlikely alternatives to reality) triggers a more global processing style. In other words, psychological distancing makes us see the forest rather than the individual trees.

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A New Science of Happiness

Dacher Keltner from “Forget Survival of the Fittest: It Is Kindness That Counts,” by David DiSalvo, Scientific American Mind (September 2009):

Dacher Keltner Recent research is suggesting that our capacities for virtue and cooperation and our moral sense are old in evolutionary terms, and these capacities are found in the emotions I write about.

A new science of happiness is finding that these emotions can be readily cultivated in familiar ways, bringing out the good in others and in oneself. Here are some recent empirical examples:

  • Experiences of reverence in nature or of being around those who are morally inspiring improves people’s sense of connection to one another and their sense of purpose.
  • Meditating on a compassionate approach to others shifts resting brain activation to the left hemisphere, a region associated with happiness, and boosts immune functions.
  • Talking about what we are thankful for—in classrooms, at the dinner table or in a diary—boosts happiness, social well-being and health.
  • Devoting resources to others, rather than indulging a materialist desire, brings about lasting well-being.

This kind of science gives me many hopes for the future. At the broadest level, I hope that our culture shifts from a consumption-based, materialist culture to one that privileges the social joys (play, caring, touch, mirth) that are our older (in the evolutionary sense) sources of the good life. In more specific terms, I see this new science informing practices in almost every realm of life.

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What Could Be Useful About Depression?

Excerpts from “Depression's Evolutionary Roots,” By Paul W. Andrews and J. Anderson Thomson, Jr., Scientific American Mind, August 25, 2009:

Depressed people often have trouble performing everyday activities, they can’t concentrate on their work, they tend to socially isolate themselves, they are lethargic, and they often lose the ability to take pleasure from such activities such as eating and sex. Some can plunge into severe, lengthy, and even life-threatening bouts of depression.

Matt exploring Musée Rodin (2005) So what could be so useful about depression? Depressed people often think intensely about their problems. These thoughts are called ruminations; they are persistent and depressed people have difficulty thinking about anything else. Numerous studies have also shown that this thinking style is often highly analytical. They dwell on a complex problem, breaking it down into smaller components, which are considered one at a time.

This analytical style of thought, of course, can be very productive. Each component is not as difficult, so the problem becomes more tractable. Indeed, when you are faced with a difficult problem, such as a math problem, feeling depressed is often a useful response that may help you analyze and solve it...Analysis requires a lot of uninterrupted thought, and depression coordinates many changes in the body to help people analyze their problems without getting distracted...

Sometimes people are reluctant to disclose the reason for their depression because it is embarrassing or sensitive, they find it painful, they believe they must soldier on and ignore them, or they have difficulty putting their complex internal struggles into words.

But depression is nature’s way of telling you that you’ve got complex social problems that the mind is intent on solving. Therapies should try to encourage depressive rumination rather than try to stop it, and they should focus on trying to help people solve the problems that trigger their bouts of depression. (There are several effective therapies that focus on just this.) It is also essential, in instances where there is resistance to discussing ruminations, that the therapist try to identify and dismantle those barriers.

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Andrews, P. W., & Thomson Jr, J. A. (2009). The bright side of being blue: Depression as an adaptation for analyzing complex problems. Psychological Review. 116 (3), 620.

La-Porte The Gates of Hell
La Porte de l'Enfer
Auguste Rodin