Tag Archives: neurons

Digging Up The Roots of Intelligence: Plant Neurobiology: A Sapling Science

Plants are passive creatures. When it comes down to it, they’re not much more than nature’s pretty green backdrop. They stay in the same place their whole lives, silently soaking up water and sunlight, growing a little bit each day, pretty much defenseless against hungry herbivores. They just don’t do much—right?

If that’s what you think – and you wouldn’t be alone – take a look at this excerpt from David Attenborough’s spectacular The Private Life of Plants, produced with the BBC:

For most plant scientists, the notion of plants as passive, unresponsive and motionless organisms is simply insupportable in view of the vast evidence to the contrary. Time-lapse photography and film show that plants do in fact move, albeit at a much slower pace than most animals. Over time, for example, the roots and shoots of many developing plants twirl out into the environment, evaluating soil content and sources of light and water, searching for the best direction to grow, looking for a foothold and—in some cases—even sniffing out neighboring plants as friend or foe.

Sometimes, plants move exceptionally quickly: flowers rush to open in time to receive spring’s flurry of pollinators; seed pods explode, sending pollen grains flying; the leaves of Mimosa pudica (the Sensitive Plant) recoil instantly when touched; and, perhaps most famously, the Venus Flytrap snaps its green jaws whenever a six-legged meal crawls its way. See the proof for yourself:


The Sensitive Plant (Mimosa pudica)

Venus Fly Trap

The field of plant physiology, which concerns cellular and molecular functions, has discovered a wide array of active signaling mechanisms important for communication both in the individual plant and between plants—mechanisms that rely on hormones, proteins, peptides and electrical signals. When attacked by hungry insects, for example, potato and tomato plants respond by increasing the production of protease inhibitors—chemicals that inhibit digestion of leafy material—not only in the wounded leaf, but in all leaves.

Recently, plant science has witnessed the emergence of a new minority advocating even greater recognition of plants as organisms that respond directly to their environments with sophisticated signaling systems. This minority—associated with a novel field called “plant neurobiology”—argues for plants as “information processing” organisms capable of true behavior and adaptation, drawing attention to the potential neurobiology underlying these abilities. As the International Laboratory of Plant Neurobiology states on its web site, “The nascent field of Plant Neurobiology has been formed based on recognition that neurobiology of humans is a most rapidly breaking field in biology today, and the reality that much of the biochemistry, cell biology and electrophysiology known in classical neurobiology exists as well in plants.”

Many of the scientists in this minority are represented by The Society of Plant Signaling and Behavior, which has already held six international symposia. Here is an excerpt from their web site:

The goal of this field is to illuminate the structure of the information network that exists within plants. Plants are dynamic and highly sensitive organisms that actively and competitively forage for limited resources both above and below ground. Plants accurately compute inputs from the environment, use sophisticated cost-benefit analysis, and take action to mitigate diverse environmental insults. Plants are also capable of refined recognition of self and non-self, and are territorial in behavior. This view sees plants as information processing organisms with complex, long-distance communication systems within the plant body and extending into the surrounding ecosystem. Our Society was originally founded in 2005 as the Society for Plant Neurobiology to reflect these views of plant function. In May 2009 the Society voted to expand its view and change its name accordingly.

Why did the Society change their name in May 2009? Why remove the term ‘neurobiology’ from their title? Their decision reflects the controversy they have inspired and the resistance they have encountered from their scientific peers. Neurobiology—the detailed study of the nervous system and the brain—has nothing to do with plants, many of their colleagues argue; plants do not have nervous systems and making parallels between their signaling systems and those of animals is unwarranted, unscientific and misleading. Just two years before the Society changed its name, thirty-three researchers—from such universities as Oxford, Yale and the University of California Davis—signed a letter of opposition questioning the rationale of the entire plant neurobiology movement and claiming that it “does not add to our understanding of plant physiology, plant cell biology or signaling.”

However, there are several striking similarities between the cellular and molecular signaling mechanisms of plants and those of animals, namely: (1) the use action potentials—a change in voltage across an excitable cell membrane; (2) voltage-gated ion channels in cell membranes; and (3) evidence of neurotransmitter-like molecules. Plants have cells capable of sensing different aspects of their environment—especially light, temperature, humidity and gravity. They respond to these environmental stimuli with directly observable and measurable developmental changes. That action potentials and neurotransmitter-like molecules could be involved in these interactions and in internal plant communication is a valid claim supported by some preliminary evidence.

So the controversy continues, for now. Whether Plant Neurobiology will take root or not is unclear, but the evidence to which they point is too intriguing to simply ignore.


Illuminating the Secrets of Mind Control in Light of the Coming Singularity

This past weekend, the 92nd Street Y hosted the 2009 Singularity Summit. Maybe you’ve already heard of Ray Kurzweil and his widely cited book The Singularity is Near, but here’s the gist just in case: Kurzweil and many others claim the exponentially increasing rate of technological development is evidence for a shift in the near future —a shift called the Singularity—during which artificial intelligence will surpass human intelligence and machines will supersede humans as the dominant sentient forces on the planet. If this sounds like something out of The Matrix and more than a little kooky—don’t worry, you’re not alone. But the Singularity Summit wasn’t just an excuse for enthusiastic futurists and computer science geeks to stand up on a soapbox and spout speculation—the Summit welcomed a diverse range of scientists whose presentations described some really fascinating current research. One that caught my attention in particular was Ed Boyden of MIT.

Boyden’s speech focused on synthetic neurobiology—a field in which researchers create technology that interacts directly with the brain—and a remarkable technique for specifically manipulating individual neurons, a technique Boyden helped pioneer. Many organisms—such as jellyfish, algae and bacteria—produce light-activated protein pumps. Using harmless viruses as vehicles to transport DNA coding for these proteins from one organism to another, researchers can make neurons in the animals they study light-sensitive as well. What’s more, by using different kinds of protein pumps—one which excites neurons in response to blue light and one which inhibits them in response to yellow light—they can precisely determine whether the neurons fire or not. Eager for an unprecedented level of control over different parts of the brain and nervous system, researchers have readily adopted the technique, successfully applying it to a range of animal models, from zebra fish to primates.

So what does any of this have to do with the Singularity? Well, during his presentation at the Summit, Boyden described attempts to make fiber optic implants for the human brain, implants that could directly stimulate or inhibit neurons with light. Let’s think about this: brain implants that precisely determine whether our neurons are firing or not? Sure, there’s great therapeutic potential here—especially for diseases that involve abnormal firing patterns, like epilepsy and Parkinson’s—but there’s also something a bit alarming. The technology Boyden described is similar to deep brain stimulation (DBS)—in which an implanted brain pacemaker regulates specific areas of neurons—but there is a crucial difference: present day DBS uses electrical stimulation, which is not nearly as precise as light stimulation. The more sophisticated the technology with which we study the brain becomes, the more we learn about the brain’s function and the better we become at treating psychological disorders; on the other hand, one can’t help but imagine how precise control of individual neurons could turn into the kind of mind control science fiction has long warned us against. Scarily, fiber optics have already been used to stimulate the brain in mice, as this little fellow demonstrates: when the light goes on, he involuntarily runs in circles:

If Kurzweil is right—and computers will soon be smarter than us—I’m sure they’ll take full advantage of any mind-controlling technology at their disposal. Who knows: maybe the Singularity already happened and we’re nothing more than a bunch of brains in vats, lapping up the rays of light that power our dream reality—all for the amusement of our supercomputer overlords.