Slide 1

PSY105 Neural Networks 1/5

1. Patterns emergeIf you graph the numbers of any system, patterns emerge2

A physical example Ball bearingLedgePin board is at a steep angle. The ball is let loose in the centre at the top and rolls through the pins to come to rest on the ledgePath of the ballPin board6The Galton Machinehttp://www.ms.uky.edu/~mai/java/stat/GaltonMachine.htmlFinal distribution after many trials is approximately normal(approximation improves with increasing number of trials) 8Rule-governed vs rule-describedFlocking starlingshttp://www.youtube.com/watch?v=4DKtj4E_issFlocking starlings

Boidshttp://www.youtube.com/watch?v=rN8DzlgMt3MBoids

BoidsThree rules, followed by individuals:separation: steer to avoid crowding local flockmatesalignment: steer towards the average heading of local flockmatescohesion: steer to move toward the average position of local flockmates

Reynolds, C.(1987), Flocks, herds and schools: A distributed behavioral model, SIGGRAPH '87: Proceedings of the 14th annual conference on Computer graphics and interactive techniques (Association for Computing Machinery): 25--34, doi:10.1145/37401.37406, ISBN 0-89791-227-614Pond SimulationRed turtles and green turtles get along. But each turtle wants to make sure it lives near some of its own.

10/14/2014PSY304 Lecture114TJP lecture 1Emergence

Turtles, Termites, and Traffic Jams : Explorations in Massively Parallel Microworlds by Mitchel Resnick15Levels of description affect both the objects we use and the answers we seek when we investigate the brain

17A hierarchy of levels in the mind/brain?Mental structuresLanguage of thoughtLower level implementationsThe brain??Goals, Beliefs, Concepts??

Perhaps the incredibly complex patterns of neural firings that occur in the brain also have higher-level descriptions in terms of information processing that is going on in the mind 10/14/2014PSY304 Lecture117TJP lecture 1

Focus on: neuronsNeurons are the cells of the brain. They appear to be integrating or combining many thousands of signal sources (from other neurons) to produce new signalsEach orange dot in the photo is a synapse (input)

19What are the key features of a neuron?And how do you decide if a feature is key20Generation of action potentialsMembranepotential(due to combined signal input)Thresholdfor firingtimeAction potentialsIncreasing due to overallexcitatory influence21Generation of PSPsAxonterminaldendriteIncomingactionpotentialPSP is one ofSmall excitatoryLarge excitatoryLarge inhibitorySmall inhibitory22Warren McCullock

1943 - First artificial neuron modelWarren McCulloch (neurophysiologist) Walter Pitts (mathematician)23