Wrap Your Mind Around Neural Networks

Artificial Intelligence is playing an ever increasing role in the lives of civilized nations, though most citizens probably don’t realize it. It’s now commonplace to speak with a computer when calling a business. Facebook is becoming scary accurate at recognizing faces in uploaded photos. Physical interaction with smart phones is becoming a thing of the past… with Apple’s Siri and Google Speech, it’s slowly but surely becoming easier to simply talk to your phone and tell it what to do than typing or touching an icon. Try this if you haven’t before — if you have an Android phone, say “OK Google”, followed by “Lumos”. It’s magic!

Advertisements for products we’re interested in pop up on our social media accounts as if something is reading our minds. Truth is, something is reading our minds… though it’s hard to pin down exactly what that something is. An advertisement might pop up for something that we want, even though we never realized we wanted it until we see it. This is not coincidental, but stems from an AI algorithm.

At the heart of many of these AI applications lies a process known as Deep Learning. There has been a lot of talk about Deep Learning lately, not only here on Hackaday, but all over the interwebs. And like most things related to AI, it can be a bit complicated and difficult to understand without a strong background in computer science.

If you’re familiar with my quantum theory articles, you’ll know that I like to take complicated subjects, strip away the complication the best I can and explain it in a way that anyone can understand. It is the goal of this article to apply a similar approach to this idea of Deep Learning. If neural networks make you cross-eyed and machine learning gives you nightmares, read on. You’ll see that “Deep Learning” sounds like a daunting subject, but is really just a $20 term used to describe something whose underpinnings are relatively simple.

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Machine Learning: Foundations

When you want a person to do something, you train them. When you want a computer to do something, you program it. However, there are ways to make computers learn, at least in some situations. One technique that makes this possible is the perceptron learning algorithm. A perceptron is a computer simulation of a nerve, and there are various ways to change the perceptron’s behavior based on either example data or a method to determine how good (or bad) some outcome is.

What’s a Perceptron?

I’m no biologist, but apparently a neuron has a bunch of inputs and if the level of those inputs gets to a certain level, the neuron “fires” which means it stimulates the input of another neuron further down the line. Not all inputs are created equally: in the mathematical model of them, they have different weighting. Input A might be on a hair trigger, while it might take inputs B and C on together to wake up the neuron in question.
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Controlling a cockroach leg with your mind

If one hack that controls amputated cockroach legs this week wasn’t enough for you, we’ve got another.

Earlier this week we saw two neuroscientists at Backyard Brains put on a show at a TED talk by connecting an amputated cockroach leg (don’t worry, they grow back) to a $100 electronic device called the SpikerBox. The SpikerBox allows students to explore the world of axons and action potentials by listening in on the electronic signals generated by the hair on the legs of a cockroach. For the finale for their TED talk, the SpikerBox guys attached an MP3 player to the cockroach leg, causing the now dead appendage to dance a little jig.

This new build – the Salt Shaker from Thinker Thing again allows students to amputate cockroach legs, pin them down with electrodes, and cause muscle contractions with the sound of science. Thinker Thing took this one step further than the neuroscientists at Backyard Brains; now you can control a cockroach leg with your mind.

The folks at Thinker Thing are using an off the shelf EEG system from Emotiv to capture the alpha, beta, and delta brainwaves of their new human test subjects. By interpreting these brain signals, they can convert these small variations in cerebral electrical activity to sound files. From there, it’s simply a matter of plugging in the Salt Shaker and moving a cockroach leg with your mind.

In the video after the break you can check out the folks at Thinker Thing playing around with their Salt Shaker and controlling a cockroach leg with a team member’s mind.

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Learning neuroscience with cockroach legs

Neuroscientists [Tim Marzullo] and [Greg Gage] wanted a way to get kids interested in neuroscience. What they came up with isn’t terribly far from something found in Frankenstein’s lab; by amputating a cockroach’s leg and attaching electrodes, they’re able to listen to the sound of neurons firing. For an even cooler demonstration, they’re able to apply a little bit of current to the leg and make the leg dance to the beat of the Beastie Boys.

The guys published an article in PLOS One and gave a TED talk demonstrating their SpikerBox, as they call their invention, to the masses. The basic idea is to amplify the electricity generated by cockroach neurons firing. By listening in on the neurons with an iPad app, [Tim] and [Greg] can set the threshold of the recording to detect the action potential of an individual neuron, and listen in on exactly what happens when a single neuron fires.

It seems like a great tool to explain the very basics of what a nervous system – and a brain, both cockroach and human – actually is. In the video after the break, you can see [Greg] playing around with individual cockroach neurons. After that, [Greg] plays the Beastie’s High Plains Drifter into the leg making the muscles contract. Truly, The Sounds of Science.

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