Download
1 / 26
270 likes | 316 Views
Bionics 3. Kevin Warwick www.kevinwarwick.com http://en.wikipedia.org/wiki/Kevin_Warwick. Animals & Experiments. Animal testing/experiments can be questioned from an ethical viewpoint Interested here more in neural aspects Not chemical Not external Behavioural? Humans are animals!.
E N D
Bionics 3 Kevin Warwick www.kevinwarwick.com http://en.wikipedia.org/wiki/Kevin_Warwick
Animals & Experiments • Animal testing/experiments can be questioned from an ethical viewpoint • Interested here more in neural aspects • Not chemical • Not external • Behavioural? • Humans are animals!
Pavlov’s Dogs • Pavlov performed experiments on digestion which earned him the 1904 Nobel Prize. These included surgically extracting portions of the digestive system from animals, severing nerve bundles to determine the effects, and implanting valves between digestive organs and an external pouch to examine the organ's contents.
Pavlov’s Dogs • Research on reflex actions involved involuntary reactions to stress and pain. Pavlov began the study of transmarginal inhibition (TMI), the body's natural response of shutting down when exposed to overwhelming stress or pain. His research showed that all temperament types responded to the stimuli the same way, but different temperaments move through the responses at different times. He felt this was due to a different type of nervous system.
Pavlov’s Dogs • It is popularly believed that Pavlov always signalled the occurrence of food by ringing a bell. However, his writings record the use of a wide variety of stimuli, including whistles, tuning forks and visual stimuli, in addition to ringing a bell. • Carl Jung continued Pavlov's work on TMI and correlated the observed shutdown types in animals with his own introverted and extroverted temperament types in humans. Introverted persons, he believed, were more sensitive to stimuli and reached a TMI state earlier. • William Sargent continued the behavioural research in mental conditioning to achieve memory implantation and brainwashing.
José Delgado • Delgado used what he called a stimoceiver, a radio which joined a stimulator of brain waves with a receiver which monitored EEG waves and sent them back on separate radio channels. • He said that Radio Stimulation of different points in the amygdala and hippocampus produces a variety of effects, including pleasant sensations, elation, deep, thoughtful concentration, odd feelings, super relaxation, coloured visions, and other responses.
José Delgado • Once Delgado stepped into the ring with a bull which had had a stimoceiver implanted. The bull charged Delgado, who pressed a remote control button which caused the bull to stop. Delgado claimed that the stimulus caused the bull to lose its aggressive instinct. • Delgado believed that his experiment with a female chimpanzee named Paddy was more significant. Paddy was fitted with a stimoceiver that detected a brain signal called a spindle. When a spindle was detected, the stimoceiver responded with a signal to the central gray area of Paddy's brain, producing an 'aversive reaction'. Within hours her brain was producing many fewer spindles.
Cockroach Backpack • At the University of Tokyo electrodes were inserted into the antennae of a cockroach – signals were sent to cause the cockroach to go forwards/backwards, left/right.
Lamprey • At Northwestern University, Mussa-Ivaldi built a two-wheeled robot that operated on the electrical signals of a lamprey’s brain. The part of the brain used in the experiment normally keeps the lamprey upright in the water. When connected up correctly, the organ can guide the robot towards a light source.
Miguel Nicolelis • Miguel Nicolelis at Duke University, North Carolina, wired a monkey brain to control a robot arm that mimicked the motions of its real arm. "It was an amazing sight to see the robot in my lab move, knowing that it was being driven by signals from a monkey brain at Duke," said [Massachusetts Institute of Technology's] Mandayam Srinivasan. "It was as if the monkey had a 600-mile- (950-km-) long virtual arm.“ • KW comment – no direct feedback (only visual).
John Chapin • Remote controlled rats! Movement signals are transmitted from a computer to the rat's brain via a radio receiver strapped to its back. One electrode stimulates the "feelgood" center of the rat's brain, while two other electrodes activate the cerebral regions which process signals from its left and right.
John Chapin II • In a separate experiment John implanted electrodes into the planning area in the brains of 6 rats. • The rats were taught to push a lever to obtain a liquid treat. • Signals were sent via the implant to cause the treat to be released without the need for the rat to actually push the lever. • 4 out of 6 rats learned they didn’t need to push the lever – thinking about pushing it was fine.
Brain Stimulation • In 1870, two German researchers named Hitzig and Fritsch electrically stimulated the brains of dogs, demonstrating that certain portions of the brain were the centres of motor function. • Bartholow, within four years, demonstrated that the same was true of human beings. • By the turn of the [twentieth] century Krause was able to do a systematic electrical mapping of the human brain, using conscious patients undergoing brain surgery.
Hess • Hess, began his research into Electrical Stimulation of the Brain in the 1930s, jolting patients' brains with shocks administered through tiny needles that pierced the skull. • His experiments included the insertion of fine electrically conductive wires into the brains of anaesthetized cats. • Given mild electrical stimulation the cats went beserk.
Penfield • During the 1940s and 50s, Penfield experimented with electrical brain stimulation on human patients undergoing surgery. • One of Penfield's discoveries was that the application on alert patients could stimulate the memory of past events.
Pleasure?? • In 1956, Olds reported on research in which he had electrically stimulated the brains of rats. • Implanting electrodes in rats' pleasure centre of the brain, he attached a button that allowed the rats to activate the electrical impulse themselves. • The rats were able to choose between food and immediate pleasure. • Olds found that the rats became so obsessed with self-stimulation that they would literally starve themselves to death. • Later repeated with monkeys
Monkeys • Using high-tech brain scans on monkeys, researchers determined that a small clump of cells are active in the formation of the desire (plan) to carry out specific body movements. • Armed with this knowledge, researchers at CALTECH implanted electrodes in the cortex of a rhesus monkey trained to play a simple video game. • A computer program, hooked up to the implanted electrodes then moved a cursor on the computer screen in accordance with the monkey's desires - left or right, up or down.
Tipu Aziz/Parkinson • Tipu’s work involves inducing Parkinsonian symptoms in monkeys, either surgically or chemically, then switching off the symptoms using implanted electrodes. • As many as 40,000 PD people around the world have benefitted from the technique. • The technique, which Aziz pioneered in the UK, has been shown to alleviate symptoms in human sufferers of PD and dystonia. • Patients have electrodes permanently implanted in their brains, wires are attached under the skin to a control chip, and a battery inserted into the chest. • We will look at this in more depth later in the course
Cultured Neural Network • Culture brain cells directly on to a recording surface and re-embody the ‘brain’ within a robotic body. • Multi-Electrode Array (MEA) allows recording from 128 electrodes across the entire culture. 200m TiN Electrodes 30m diameter Neurone
Embodiment • Re-embodiment is essential • Without it the neurones are simply talking to themselves resulting in no meaningful input / output relationship. • This can be demonstrated in animals that have developed in a sensory deprived environment – the relative areas of the brain simply do not form the appropriate connections and the animal has limited functionality. • Embodying the culture with a robot body means that it’s actions will result in specific sensory input which in turn should influence future ‘decisions’.
Previous work Animat (Potter’s group) Created a closed loop system which successfully demonstrated approach / avoidance behaviour. Used a similar system to fly a simulated plane. Angle of roll mapped on to culture, plane stable in strong simulated winds. T. B., Demarse, D. A. Wagenaar, A. W. Blau and S. M. Potter, (2001). ‘The neurally controlled Animat: biological brains acting with simulated bodies’. Autonomous Robots no.11, pp.305–310
Methodology • Culture to Robot Mapping • How can the activity of the culture be mapped to the robot’s actuators and the robots sensors on to stimulate the culture. • Biological Aspects • The methods behind culturing maintaining and interfacing with neurones. • Neural signal interpretation - Dimensionality reduction and processing before sending to robot.
Culture Protocol • MEAs coated with PDL (Poly-d-lysine) which allows neurones to adhere to the surface • Primary cortical neurones enzymatically dissociated – this breaks down the connective tissue before trituration which breaks off the axons and dendrites effectively leaving neural cells in a ‘blank’ state. • Dissociated cells are suspended in media and added to the MEA chamber. • Cells are fed day 1 and every 4 days after with a glucose based media • After a 1-2 days connections spontaneously reform and begin to resume activity, initially with single spikes and after roughly a week complex burst patterns are seen.
Protocol Modifications • Selective coating allows the neural density to be increased near the electrodes • The use of younger animals may result in undifferentiated cells that are be able to adjust to be the most suitable cell type for the location they land in.
Spike Sorting • A single electrode may pick up signals from over 100 neurones. • It is essential to extract the useful signals from the noise and attempt to separate out the spikes from different neurones. • Spikes that originate from different neurones have different voltage profiles (shapes) – although this is not always true. • Before transmitting this information to the robot - need to apply some form of dimensionality reduction, possibly involving Principal Component Analysis (PCA)
