Welcome to the 21st installation of Encephalon, a blog carnival devoted to neuroscience. The carnival is organized by the inimitable Neurophilosopher, and today hosted here at Ouroboros.

Neuroscience is of major interest to biologists of aging, mainly because so many diseases of aging are diseases of the brain. Hence, we’ve paid a great deal of attention to recent findings on neurodegeneration (especially Alzheimer’s disease). Today, however, we’re (mostly) not going to focus on these maladies in particular, but on the basic science of the brain and mind. Hardcore biogerontologists should nonetheless read on: We can’t truly appreciate the scope and symptomology of neurodegenerative diseases without understanding how the brain works throughout the lifespan (and the other sorts of things that can go wrong).

Without further ado, then…Encephalon 21.


The previous paragraph notwithstanding, we will begin with an article that’s fairly germane to this blog’s interest in neurodegeneration and the prospect of cellular therapies that might allow regeneration of the aging brain. Dan at Migrations points us toward a recent review describing the current state of knowledge regarding neural progenitors in the adult brain. Specifically, the article discusses the factors responsible for maintaining the stem cell niche, i.e., the microenvironmental factors that keep progenitor cells happy, healthy and multipotent.

On the road toward generating a normal adult brain and central nervous system, a multitude of things can go wrong. In some ways, it’s surprising that it happens successfully as often as it does; when it doesn’t, the results can be tragic. Fortunately, thanks to the work and ingenuity of a few inspired people over the years, there are solutions to some of the myriad possible accidents of development. Vaughan at MindHacks celebrates the achievement of one of these individuals: John Holter, who developed the pressure valve used to treat hydrocephalus in children with spina bifida. While the invention came too late to help his own child, the device has saved thousands of lives in the fifty years since it was first tested.

While large brains evolved many times independently, the cells that make up brains (and nervous systems) are profoundly similar across widely divergent species. We can therefore learn a great deal about the development and function of nervous systems by studying what some would call the “lower metazoans” (others, including myself, simply call them “smaller and unluckier”). At the Skeptical Alchemist, Steppen Wolf talks about what we can learn by studying the ciliated neurons in the humble roundworm C. elegans. These cells may hold the key to understanding such disparate processes as vision and the accumulation of excess fat in obese mammals.

A process as complex as vision has many secrets, of course, and despite the awesome power of nematode genetics it is unlikely that ciliated neurons will unlock all of them. Much of the action takes place in the visual cortex, at a level (and location) far removed from the primary photon receptors in the retina. Some of the features of this higher-level processing results in visual illusions — and by studying these, we can sometimes learn a great deal about the neural architecture of vision. Chris at Developing Intelligence provides an example with his discussion of the retinal blindspot and the illusory contour effect. There’s more to it than, er, meets the eye.

At an even higher level of processing, we can integrate the inputs from multiple senses as well as memory and experience to deduce the internal mental state of others. Johan (president of the Phineas Gage Fan Club) has a lengthy and erudite discussion of the scholarly controversies regarding theories of how our minds form models of other minds.

Psychological therapists unquestionably engage in an extremely complex form of modeling other people’s minds. While there are certainly useful rules and heuristics for therapists to follow, any given instance of therapy is highly personal, requiring integration of a vast array of information and a finely honed sense of empathy. Is it conceivable that a machine could ever substitute for even part of this function? The brain trust at Nintendo seems to think so: Dr. Deb describes a therapy “game” that will soon be released for the Nintendo DS. No couch required. One obvious question: can it treat gaming addiction?

On a somewhat more serious note: What is consciousness? Will the steady progress of reductionist neuroscience (and systems-level analysis of the emergent properties of the most complex system we have discovered to date) ever be able to answer this question? More precisely: Are there “easy” and “hard” questions about the nature of consciousness, and does solving the “hard” questions risk the demystification of consciousness itself? At PsyBlog, Jeremy tackles these weighty questions in a lengthy article, poetically entitled “Will Solving the ‘Hard’ Problem of Consciousness Unweave the Rainbow?

Our neurology (and understanding of it) can profoundly influence our self-image and beliefs about the world around us. This is perhaps especially true when the brain and nervous system misbehave. The Neurophilosopher describes one example: Fyodor Dostoyevsky, who was an acclaimed and prolific author, a great thinker — and an epileptic. The Neurophilosopher reviews what we know about Dostoyevsky’s illness and symptoms, and discusses the impact that his malady had on his personality and worldview.

By now you’re probably wondering how you’ll remember all of this new information, and cursing the limitations of human memory. Therefore, I feel it is only appropriate to remind you that it could be a lot worse: In very rare cases, generally pursuant to injury, people can forget their entire lives. The author of Biotunes tells us about a case of dissociative amnesia: A man who had sustained traumatic brain injury while training for WWII later walked away from his wife and family for 20 years, basically because…he forgot about them.

Thanks for reading. For your next neuroscience fix, Encephalon 22 will be hosted on May 7 at John Hawks Anthropology Weblog. Submissions can be sent directly to him, or to encephalon.host [at] gmail.com.

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