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Salk researchers and collaborators have achieved critical insight into the size of neural connections, putting the memory capacity of the brain far higher than common estimates. The new work also answers a longstanding question as to how the brain is so energy efficient and could help engineers build computers that are incredibly powerful but also conserve energy.
"This is a real bombshell in the field of neuroscience," says Terry Sejnowski, Salk professor and co-senior author of the paper, which was published in eLife. "We discovered the key to unlocking the design principle for how hippocampal neurons function with low energy but high computation power. Our new measurements of the brain's memory capacity increase conservative estimates by a factor of 10 to at least a petabyte, in the same ballpark as the World Wide Web."
Our memories and thoughts are the result of patterns of electrical and chemical activity in the brain. A key part of the activity happens when branches of neurons, much like electrical wire, interact at certain junctions, known as synapses. An output 'wire' (an axon) from one neuron connects to an input 'wire' (a dendrite) of a second neuron. Signals travel across the synapse as chemicals called neurotransmitters to tell the receiving neuron whether to convey an electrical signal to other neurons. Each neuron can have thousands of these synapses with thousands of other neurons.
Nanoconnectomic upper bound on the variability of synaptic plasticity (10.7554/eLife.10778)
(Score: 0) by Anonymous Coward on Friday January 22 2016, @08:45AM
In single celled organisms and many small multicellular organisms the term memory doesn't really mean the same thing as when we talk about memory in humans (or larger animals).
While their behaviour may appear complex it's often the result of a very simple set of rules, effectively an algorithm. Ant foraging behaviour is a good example of complex and highly effective behaviour emerging from simple pheramone following rules in a noisy system.
Generally when we talk about memory in these animals all we mean is tweaking the parameters of this algorithm not the emergence of new behaviour. This is memory in that an organisms behaviour is influenced by its history, but it isn't the same thing a person remembering where they left their keys, or how to play the piano.
(Score: 1, Interesting) by Anonymous Coward on Friday January 22 2016, @07:11PM
While their behaviour may appear complex it's often the result of a very simple set of rules, effectively an algorithm.
Same for most of the comments on internet forums or even the commenters themselves no? ;)
>90% of Stephen Hawking's behavior is as predictable as >90% of a single celled creature's behavior. It's the other percentage that's the interesting part...
(Score: 2) by rleigh on Friday January 22 2016, @11:03PM
I'm not so sure about that. Where do you draw the line between "a simple set of rules with some random noise" and "full sentience and recall"? How much of our own behaviour is actually simple? Probably the vast majority of it--think about how much you are doing all the time without any concious thought; from simple muscular action to complex but habitual reflexes, and skilled work.
From neuroscience lectures I've attended looking at the wiring of the ant nervous system, showing how pheremone receptors hook into pre-programmed actions via memory, essentially using a hardwired addressing system, it is the case that a lot of it is emergent behaviour, coupled with a simple memory to allow adaption of a fixed set of responses to unique stimuli. How the "mushroom body" functions, etc. There are some very interesting parallels to be drawn with computer systems here, including what could very well be an actual "memory bus". Clearly a person is vastly more complex; many orders of magnitude so. But are our brains fundamentally all that different? As you progress up the evolutionary ladder through fish, mammals have additional layers of complexity (size, folding), and a rather more plastic development process, but I would also suspect that the real core stuff will have been conserved through evolution.
For someone "remembering the location of their keys", how different is this from a response to a pheremone? It seems that the pheremone triggers the memory, which leads to an action. Could the trigger of "my key" lead to exactly the same thing, albeit at a more abstract level--the trigger and the response not being external physical events? Obviously I don't have an answer to that since we don't yet know, but over the last few years it's been really interesting that with e.g. the ability to visualise individual neurons firing in real-time, we can actually map out what's going on in simple systems under different conditions, which will inevitably lead to insights into how it works in ourselves. It will certainly be interesting once we can look at ourselves in detail; undoubtedly it will also provide some interesting philosophical insights as well! It's also interesting to see more details at the molecular level regarding e.g. exactly how synapse firing and resetting works with the structure of synaptotagmin and other molecules.
(Score: 0) by Anonymous Coward on Saturday January 23 2016, @12:43AM
It's not different, but you're making the mistake most people make. They elevate other things to the magical, grandiose level of a human rather than bringing the human down to the level of the things.
We're not special. Get over it.
(Score: 2) by rleigh on Saturday January 23 2016, @10:15PM
Huh, I said the exact opposite of what you are saying here.
(Score: 2) by tathra on Saturday January 23 2016, @09:52AM
"full sentience" and "a simple set of rules and random noise" are not mutually exclusive. humans don't really have free will, we function based on algorithms running in our subconscious and body, via hormones and neurotransmitters, and then the left hemisphere produces a narrative out of whats already been decided - whether it makes sense or not, your brain will construct a narrative making you think it was your choice, and create some kind of rationalization for it, even though you really had no choice in it at all. after the choice has been made, then "free will" can come into play and you can reason your way into a better choice, such as lighting up a cigarette by habit and then suddenly realizing you're trying to quit, or heading to a bar to cheat on your wife but then realizing its a bad idea and turning around when you're halfway there.