Running the numbers — trillion synapses — 4. Early-generation personal computers had — at best — a few megabytes of hard-drive information storage capability. To put this in perspective, the computer onboard the first Apollo spacecraft that landed on the moon had an operating system with just 64 kilobytes 64 KB of memory storage capability.
The computer in that example could handle just over 64 thousand bytes, which is just over 64 thousand characters of information. Today, most digital toasters have more computing power than Apollo 11 had, and your average smartphone is literally light-years ahead the computer that guided and controlled that spaceship. In reality, glial cells heavily influence the excitability of a neuron. To quantify storage capacity, any individual bit is no different from any other bit.
In the brain, a given synapse may be able to exist in possible states, but might only encode the information necessary to calibrate its own response so it is not overactive. This neuron cannot be used to store yet another digit of pi you are trying to remember.
The closest analogy in computer science is the harvard execution model, where machine instructions and data are kept in different areas. The brain is like this, but on steroids. Not all data is equal. In the end, applying information theory on neurons requires knowing how many bits each individual factor adds to a given neuron.
The only similarity between the brain and a computer is that they are both are capable of turing-complete execution. Last updated 9 November The brain probably stores around TB of data.
Support According to Forrest Wickman, computational neuroscientists generally believe the brain stores terabytes of data.
These assumptions are simplistic as he points out. In particular: synapses may store more or less than one byte of information on average some information may be stored outside of synapses not all synapses appear to store information synapses do not appear to be entirely independent We estimate that there are 1. One terabyte is equal to about 1, gigabytes or about 1 million megabytes; a petabyte is about 1, terabytes. We welcome suggestions for this page or anything on the site via our feedback box , though will not address all of them.
From the ashes of the old verities is arising a very different framework for thinking about ourselves and how our brains make sense of the world.
Historically, philosophers have debated how much of what we know is based on instinct, and how much on experience. At one extreme, the rationalists argued that essentially all knowledge was innate. At the other, radical empiricists, impressed by infant modifiability and by the impact of culture, argued that all knowledge was acquired. Knowledge displayed at birth is obviously likely to be innate. A normal neonate rat scrambles to the warmest place, latches its mouth onto a nipple, and begins to suck.
A kitten thrown into the air rights itself and lands on its feet. A human neonate will imitate a facial expression, such as an outstuck tongue.
But other knowledge, such as how to weave or make fire, is obviously learned post-natally. Such contrasts have seemed to imply that everything we know is either caused by genes or caused by experience, where these categories are construed as exclusive and exhaustive.
But recent discoveries in molecular biology, neuroembryology, and neurobiology have demolished this sharp distinction between nature and nurture. One such discovery is that normal development, right from the earliest stages, relies on both genes and epigenetic conditions. For example, a female XX fetus developing in a uterine environment that is unusually high in androgens may be born with male-looking genitalia and may have a masculinized area in the hypothalamus, a sexually dimorphic brain region.
On the other hand, paradigmatic instances of long-term learning, such as memorizing a route through a forest, rely on genes to produce changes in cells that embody that learning. If you experience a new kind of sensorimotor event during the day — say, for example, you learn to cast a fishing line — and your brain rehearses that event during your deep sleep cycle, then the gene zif will be up-regulated.
Improvement in casting the next day will depend on the resulting gene products and their role in neuronal function. First, what genes do is code for proteins. Strictly speaking, there is no gene for a sucking reflex, let alone for female coyness or Scottish thriftiness or cognizance of the concept of zero. A gene is simply a sequence of base pairs containing the information that allows RNA to string together a sequence of amino acids to constitute a protein. Second, natural selection cannot directly select particular wiring to support a particular domain of knowledge.
Blind luck aside, what determines whether the animal survives is its behavior; its equipment, neural and otherwise, underpins that behavior. Representational prowess in a nervous system can be selected for, albeit indirectly, only if the representational package informing the behavior was what gave the animal the competitive edge. Hence representational sophistication and its wiring infrastructure can be selected for only via the behavior they upgrade.
Third, there is a truly stunning degree of conservation in structures and developmental organization across all vertebrate animals, and a very high degree of conservation in basic cellular functions across phyla, from worms to spiders to humans. All nervous systems use essentially the same neurochemicals, and their neurons work in essentially the same way, the variations being vastly outweighed by the similarities.
Humans have only about thirty thousand genes, and we differ from mice in only about three hundred of those; 4 meanwhile, we share about Our brains and those of other primates have the same organization, the same gross structures in roughly the same proportions, the same neuron types, and, so far as we know, much the same developmental schedule and patterns of connectivity. Fourth, given the high degree of conservation, whence the diversity of multicellular organisms? Molecular biologists have discovered that some genes regulate the expression of other genes, and are themselves regulated by yet other genes, in an intricate, interactive, and systematic organization.
But genes via RNA make proteins, so the expression of one gene by another may be affected via sensitivity to protein products. Additionally, proteins, both within cells and in the extracellular space, may interact with each other to yield further contingencies that can figure in an unfolding regulatory cascade. Small differences in regulatory genes can have large and farreaching effects, owing to the intricate hierarchy of regulatory linkages between them.
The emergence of complex, interactive cause-effect profiles for gene expression begets very fancy regulatory cascades that can beget very fancy organisms — us, for example. Fifth, various aspects of the development of an organism from fertilized egg to up-and-running critter depend on where and when cells are born. Neurons originate from the daughter cells of the last division of pre-neuron cells. Whether such a daughter cell becomes a glial supporting cell or a neuron, and which type of some hundred types of neurons the cell becomes, depends on its epigenetic circumstances.
Moreover, the manner in which neurons from one area, such as the thalamus, connect to cells in the cortex depends very much on epigenetic circumstances, e. This is not to say that there are no causally significant differences between, for instance, the neonatal sucking reflex and knowing how to make a fire.
Differences, obviously, there are. Genes and extragenetic factors collaborate in a complex interdependency. Recent discoveries in neuropsychology point in this same direction. Hitherto, it was assumed that brain centers — modules dedicated to a specific task — were wired up at birth. For example, the visual cortex of a blind subject is recruited during the reading of braille, a distinctly nonvisual, tactile skill — whether the subject has acquired or congenital blindness.
Even more remarkably, activity in the visual cortex occurs even in normal seeing subjects who are blindfolded for a few days while learning to read braille. The blindfold is essential, for normal visual stimuli that activate the visual cortex in the normal way impede acquisition of the tactile skill.
For example, if after five days the blindfold is removed, even briefly while the subject watches a television program before going to sleep, his braille performance under blindfold the next day falls from its previous level.
If the visual cortex can be recruited in the processing of nonvisual signals, what sense can we make of the notion of the dedicated vision module, and of the dedicated-modules hypothesis more generally? What is clear is that the nature versus nurture dichotomy is more of a liability than an asset in framing the inquiry into the origin of plasticity in human brains.
It is not that there is nothing to it. But it is like using a grub hoe to remove a splinter. That is, after all, a good method for storing tools and paper files — in a particular drawer at a particular location. Lashley trained twenty rats on his maze. Next he removed a different area of cortex from each animal, and allowed the rats time to recover.
He then retested each one to see which lesion removed knowledge of the maze. There is no such thing as a dedicated memory organ in the brain; information is not stored on the filing cabinet model at all, but distributed across neurons. A general understanding of what it means for information to be distributed over neurons in a network has emerged from computer models.
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