You have put your finger on a major challenge of modern neuroscience. Getting the connectome would be likely to lead to major progress in understanding how brain circuits process information. You are right that the task is not exactly analogous to sequencing the genome because of differences among individuals. Here is what would come out of this achievement: We would be in a position to identify circuit principles of how brain wiring is organized. Right now our knowledge of circuits is extremely limited because we can trace only one or a few connected neurons at a time. Knowing the detailed layout of even a small part of the brain would be a tremendous achievement.

By the way, literally mapping all the connections in an entire brain would be a gigantic task and not necessarily the right thing to want - that’s 100 billion neurons, each getting around 10,000 connections or so from other neurons. It might be better to get a detailed map of a small bit of brain and combine this with various types of lower-resolution maps.

For clinical application in the next decade or so, invasive approaches for neural prosthesis are the likely state of the art. But I do agree with your concerns. I imagine these may be addressable by a combination of materials science and biocoatings. On the longer term, non-invasive approaches have a lot of room for future development. I think these will be interesting to researchers long before they enter clinical use for reasons having to do with cost. The low-pass filtering you mention is relevant to electric-current based measurement techniques such as EEG and focal stimulatation of brain tissue with transcranial magnetic stimulation (TMS). For methods such as functional MRI other factors are the problems of brain movement and low signal-to-noise from the agent that is being imaged. Both of these could be answered if an injectable agent were developed to generate a large activity-related signal.

This question refers to futurist Ray Kurzweil’s claim that soon, computers will match the human brain in some way, at which point life will change forever. I think the question is posed poorly, but still interesting. Let me turn it around. If you give me two decades, I can arrange to produce an information processing device that is capable of feats beyond any known computer, runs on 12 watts of power, contains a million billion (10^15) components, and will work for the better part of a hundred years. That’s what we are. The necessary material is a fertile man and woman, their commitment to raising the child well, and a few million dollars to cover upbringing and education.

Now, the kicker is the 12-watt figure, which is less power than the light inside a refrigerator. Without meeting that benchmark, we may as well go with my plan, i.e. make a person. I believe that the feat will never be accomplished by engineering because there is no clear motivation to ever do so.

However, the question contains several interesting points. First, the major technical challenge is not the development of computing power. Instead, it’s the question of understanding brains well enough to get a handle on what they are doing. For example, human brains carry out pattern recognition and assign value to decisions by rules that aren’t understood at a computational level. We can still talk about the rules - for instance, we assign value to our decisions using our emotions, which guide us to value some outcomes more highly than others - but not with enough sophistication to build a device that does these things.

Second, in a sense Kurzweil is thinking too small. Our brains are good at some tasks and bad at others. For instance, no computer in the world can reliably distinguish an image of a dog from that of a cat, yet many toddlers do it effortlessly. On the other hand, our brains are poorly equipped to evaluate risks and benefits on very long time scales. Think of our inability as individuals to resist a heart disease-inducing meal, or as a society to refrain from generating greenhouse gases. Why not design machines that make up for our brains’ weaknesses, and end up with tools to help us flourish? The alternative is to build a pet-sorting machine that can’t plan ahead.

Occasionally high school students work in my lab, but it depends on the student and on whether there’s a suitable project to help with. By all means, get in touch.

Francis Crick wrote that when he was a boy, he decided he would be a scientist. But he was worried that by the time he grew up “everything would have been discovered.” His mother said “Don’t worry, Ducky. There will be plenty left for you to find out.” When it comes to neuroscience, I’m with Crick’s mother. Neuroscience is one of the most exciting areas of basic research - to my mind it can’t be beat. We’re in for many exciting decades.

As for other occupations, there are opportunities in private-sector industries ranging from the development of drugs and therapies to the design and refinment of medical devices such as neural prostheses. If you are ever in a position to do so, visit the Society for Neuroscience meeting (in Chicago in 2009; www.sfn.org). Tens of thousands of research posters, hundreds of private-industry booths. I find it mind-blowing.

In addition to surveys, there is also behavioral neuroscience involving low-tech measurements. The McGurk effect, Libet’s reaction time task, the Wisconsin Card Sorting Task, and the Iowa Gambling Task come to mind. Also, poke around Eric Chudler’s website, http://faculty.washington.edu/chudler/neurok.html

I have wondered which species have sweet receptor variants that might let them like Diet Coke (i.e. aspartame). Mice don’t (that’s in Welcome To Your Brain). But this question might strike you as being on the simple side.

That’s a funny skill. I wonder what your rules are for pronouncing the unnatural sequences. Learning sequences the normal way, forwards, is a part of how our memories seem to work naturally in cases that include spatial navigation and storytelling. In your case you probably have a good working memory to hold the information while you manipulate it.

As a child I wanted to be a physicist. In college it seemed that physics was mature enough that it would be hard to make a big contribution in my lifetime. So I switched to another fundamental question, neuroscience. I was curious about philosophical questions such as how matter can produce consciousness and complex thoughts.

Currently I am interested in autism, in which a core part of our identity as social animals seems to be missing.

Yes. From a certain point in the brain upward (or forward, depending on how you orient the nervous system) everything is crossed. The left hemisphere controls the right half of the body. I can’t give you a good explanation of what advantage this setup offers.

Memory is thought to involve physical changes in the structure of the brain. A lot of current research addresses the possibility that memories are “written” as changes in the strength of connections between neurons (synapses). But new synapses can form too, and the composition and shape of neurons may change. All of these topics are studied at the level of cells and proteins, but how they form memories is not known. You should become a neuroscientist!

In regard to why some things are hard to remember, memory formation is highly dependent on attention and whether the thing remembered falls into a pattern that is natural for our brains to learn, such as a melody or sentence. In addition, different forms of memory recruit different brain regions. Intense fear allows you to learn in one try, but for obvious reasons it’s a bad idea to learn everything this way.

Yes. The brain is capable of some change throughout life. Depending on what was lost, these “plasticity” mechanisms can compensate. For instance, some rewiring after a minor stroke is possible. However, peripheral damage (for instance if your eyes are damaged) cannot be recovered in this way.

Sleep contains many levels of depth. In mammals and birds, the brain can come up from the deepest levels of sleep to a state in which electrical activity resembles waking behavior, but the muscles (except for the eyes) are immobilized by a center in the brainstem. As a result, dream sleep is also called rapid eye movement (REM) sleep. Neuroscientists think dreams result from the activation of sequences of activity that are likely to occur because of the arrangement of wiring, combined with mechanisms for making sense of the sequences - even when they are nonsensical. Night terror is reported to happen at times of fast arousal out of non-REM sleep (see www.ncbi.nlm.nih.gov/pubmed/2098614). It might involve the amygdala, which is activated in fearful situations.

Thank you for reading the book! It seems likely that you could do quite well. Since you have learned to distinguish the distinctive sounds of Korean, you have a learned pattern for comparison. Patricia Kuhl has found that babies make these distinctions at quite an early age. However, you may require a lot of practice. My first language was Chinese, which I have mostly forgotten. My accent is better than a naive learner, but I still have quite an accent. Try total immersion.

Just like everyone, we are social animals. There are all kinds! My biologist and physicist friends are more interested in music and reading than the general population, and less interested in television. Scientists are often a pretty international crowd, which leads to less interest in baseball and U.S. football, and more interest in soccer. When it comes to work, I personally feel more kinship to working artists than I do to doctors, lawyers, or business types. Scientists tend to be friends with other scientists, but that’s probably because we see each other a lot at work.

However, my mind is already filling with exceptions to every one of these generalizations. Why not go find a scientist and see for yourself!