Perfect map of brain reveal how information flows:

‘A perfect map of brain would reveal how information flows' - superb point but all we have are some traces of electrical signal flows through interconnected networks of neurons. There certainly seems to be some extensive control mechanisms (software) which determine how signals flow among which available connections. We all have no idea about what information is represented by those signal flows how it is stored also recalled also how it influences our actions - just for starters.

Nobody can comprehend what our computers are doing from a map of circuit interconnections or even a trace of electrical signal flows within the circuits. We cannot conclude precisely what our computers are doing even with list of all programs which are loaded also copies of their instruction source codes. With a list of all programs also data loaded into storage we might have a chance given enough computers also time to perform necessary analyses. Even then, feasibility of such an undertaking could rival sequencing of genome, just to find out which I am just entering this comment into your comment entry box.

There is an enormous amount of critical information about brain which we are not even aware of yet - information which having an enormously costly, highly detailed map of brain physiology will not even suggest to us.

What is memory capacity of human brain? Is there a physical limit to the amount of information it can store?

My brain is full," a student with a particularly tiny head asks his classroom teacher in a classic Far Side comic by Gary Larson. Answer to this question would be, "No, your brain is almost certainly not full." Although there must be a physical limit to how many memories we can store, it is extremely large. We do not have to worry about running out of space in our lifetime.

Human-brain consists of about one billion neurons. Each neuron forms about 1000 connections to other neurons amounting to more than a trillion connections. If each neuron could only help store a single memory running out of space would be a problem. You might have only a small number of gigabytes of storage space, alike to space in an iPod or a USB flash drive. However neurons combine so that everyone helps with many memories at a time, exponentially increasing brain's memory storage capacity to something closer to around 2.5 petabytes (or a million gigabytes). For comparison, if your brain worked like a digital video recorder in a television, 2.5 petabytes would be sufficient to hold three million hours of TV shows. You would have to leave TV running continuously for more than 300 years to use up all that storage.

Can an old head injury suddenly cause detrimental effects much later in life?

Although a brain injury from a car accident or a collision during a football game often seems to cause a sudden change to cognitive ability years later, this change does not just appear out of blue damage has been building up slowly, unnoticed, over time.

Post injury progressive brain deterioration that may occur likely reaches a tipping point, after which loss of function "suddenly" becomes obvious. Depending on the type and severity of traumatic brain injury (TBI), it can accelerate memory loss or increase a person's chance of succumbing to Alzheimer's disease.

TBI commonly damages nerve fibers in brain called axons. These thin, tubes like structures transmit electrical as well as chemical signals which are vital for carrying information among different regions of brain. For unknown reasons, these fragile structures not only disconnect shortly after injury but can continue to disconnect even for decades later in some patients. Once disconnected, blunt end of an axon seals itself off, swells with fluids, enzymes and proteins and eventually bursts. When axons burst open, they often distribute amyloid proteins through neighbouring brain tissue. These sticky proteins are a hallmark of Alzheimer's, and in fact many TBI patients exhibit signs of dementia later in life that mimic deterioration observed in Alzheimer's patients.

In addition, with axons disappearing or not functioning well after TBI, a person's ability to process new information may slow down. Existing axons may compensate for damage by growing electrical signalling and thus restoring normal speed of information processing in brain. This provisional fix, nevertheless, it can cause these axons to turn into even more sensitive to damage if a second concussion occurs.

Most people with TBI will have progressive axonal damage, but it is difficult to predict who will suffer from cognitive changes years later. TBIs have a devastating effect on society, with more than 1.5 million cases documented in U.S. every year. Currently no therapies exist for either short- or long-term damage, which means for now best treatment is protection and prevention.