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Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science.

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Presentation on theme: "Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science."— Presentation transcript:

1 Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Part I: Introduce you to whats happening in Artificial Intelligence Part II: Give you an appreciation for the big picture Why it is a grand challenge Done

2 Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Part I: Introduce you to whats happening in Artificial Intelligence Part II: Give you an appreciation for the big picture Why it is a grand challenge Done

3 Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Looking at the Science Engineering vs. Science Introduction to Cognitive Science Cognitive Psychology 1 Cognitive Psychology 2 Cognitive Development Linguistics Neuroscience Philosophy

4 Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Looking at the Science Engineering vs. Science Introduction to Cognitive Science Cognitive Psychology 1 Cognitive Psychology 2 Cognitive Development Linguistics Neuroscience Philosophy

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6 Why Study Neuroscience? Neuroscience: study of the nervous system physical structure and physical processes 1.Scientific interest – how to get a complete picture Thoughts algorithms neurons molceules 2.Test psychology/linguistics theories Example: visual buffer idea, test what is active in brain Example: test for existence of language module 3.Find out something about cognitive architecture Capabilities of a proposed architecture depend on physical structure Knowing structure/processes should give an idea of architecture 4.Important to understand relationship: physical structure information processing capabilities Improve treatments for damage (accident or disease) Know human limits Better learning methods Better computer systems to support humans (compensate for weakness)

7 Study at Different Scales 1m – CNS 10cm – systems (vision system) 1cm – maps 1mm – networks 100 m – synapses 1Å – molecules (neurotransmitters)

8 Study at Different Scales 1m – CNS 10cm – systems (vision system) 1cm – maps 1mm – networks 100 m – synapses (know a bit about this) 1Å – molecules (neurotransmitters)

9 Study at Different Scales 1m – CNS 10cm – systems (vision system) 1cm – maps (dont know much about this) 1mm – networks (dont know much about this) 100 m – synapses (know a bit about this) 1Å – molecules (neurotransmitters)

10 Central Nervous System

11 Cerebrum Cerebellum Brain stem

12 Cerebrum Cerebellum Brain stem

13 Compare Brains of Other Animals Human similar to rat or monkey Early research tried to find special neural cells which were unique to humans Didnt find any …But human brain bigger Seems not special cells, but more of them and more connections

14 Animal Encephalization quotient Man 7.4–7.8 Bottlenose dolphin 5.3 Chimpanzee 2.2–2.5 Whales 1.8 Gorilla 1.5–1.8 Fox 1.6 African elephant 1.3 Dog 1.2 Squirrel 1.1 Cat 1.0 Horse 0.9 Sheep 0.8 Mouse 0.5 Rabbit 0.4

15 Brain Development Macaque monkeys born with 60% of brain size Chimpanzee – 46% Human – 25%... Brain growth rate of foetus same… but… Human brain continues growth at rapid fetal rate for 2 yrs Child has higher density of connections Gradually eliminated Reach adult values by about 10yrs Windows for development 8 months can distinguish two foreign language sounds 12 months cannot Strabismus can be corrected in early years Infants born without callosum compensate (other pathways?)

16 Brain Development Plasticity of brain in children Language impairment produced by brain injury can recover if before age 5 Infants who had left half brain removed many linguistic functions normal

17 Synapses Release neurotransmitter chemicals Excitatory Inhibitory

18 Synapses Repeated stimulation can increase synaptic strengths For days or even weeks Learning?

19 Neurochemical Systems At least 40 different substances Serve a multitude of different functions 2 types Neurotransmitter act in synapse Neuromodulator Act more globally … but extremely specific functions Nanogram of angiotensin II : intense and prolonged drinking Acts as trigger

20 Neurochemical Systems Psychoactive drugs Mimic/enhance/disrupt effects of bodys neurochemicals Molecular structures may resemble neurotransmitters LSD similar to seratonin Mescaline similar to dopamine Cocaine blocks reuptake of neurotransmitter More neurotransmitter remains in synapse to stimulate further

21 Teuvo Kohonen (Artificial Neural Network researcher) To describe the global meteorological system around the earth would be an extremely trivial task compared with description of the complete behaviour of the brain.

22 Fascinating Brain Facts… 100,000,000,000 = neurons are irretrievably lost each day Each neuron connects to 10, ,000 others About or synapses Every person on planet make phone calls same number of connections as in a single human brain in a day Grey part folded to fit - would cover surface of office desk The gray cells occupy only 5% of our brains 95% is taken up by the communication network between them About 2x10 5 km of wiring Pulses travel at more than 400 km/h (250 mph) 2% of body weight… but consumes 20% of oxygen All the time! Even when sleeping Any loss of oxygen… cells die in minutes… Damage permanent in adults

23 Thats the brain hardware…

24 Thats the brain hardware… How do we find how different parts perform different functions?

25 Mapping Functions to Brain Areas See what disabilities result from specific physical damage In humans wait for accident In animals do damage deliberately To see where axons terminate Inject dye, transported along axon Slice up brain and examine under microscope Insert microelectrodes Into a single neuron Monitor changes in electrical potential Brain imaging While patient is doing a particular task

26 Imaging Positron Emission Tomography (PET) Inject radioactive glucose Gets absorbed by active regions Get the subject to do a task for about two minutes Record image Functional magnetic resonance imaging (fMRI) Hemoglobin: metalloprotein red blood cells Carries oxygen Hemoglobin diamagnetic when oxygenated paramagnetic when deoxygenated

27 More Brain Facts… In right-handed individuals (91% of people) Right side of the brain controls: musical talent, fantasy, imagination, dreams, drawing and painting. Left side of the brain controls: mathematical ability, ability to solve logic problems, language skills, remembers names, dates, and facts

28 Mapping Functions to Brain Areas

29 Maps change with experience Microelectrodes to map monkeys hand and fingers area Trained monkey rotating disk for food reward After 20 weeks… Brain area for hand had expanded markedly Mapping Functions to Brain Areas

30 Innate or Learned? Nature or Nurture? Major neural pathways very similar in all mammals Suggests genetic hardwiring Study of eye in water flea Made cloned insects (genetically identical) Studied neurons Same number of sensory neurons, and connect to same number of cells Different number of synapses, and shape of axons Similar results for pigeons Final system could be quite different in cloned animals

31 Neuropsychology Tries to discover relationships between Neuroscience and Psychology …or between : Cognitive models of information processing And structures and processes in the brain Examples: Study functions of people who have suffered brain damage Build an artificial neural network to solve some problem (In a biologically plausible way) Then damage the network Study the results and compare with real patients Imaging techniques (as discussed before)

32 Neuropsychology studying Alexia Alexia: damage to brain causes loss of ability to read Ability to read and write can be affected, while speech is normal Theoretical model of reading: dual route (parallel processing) Lexical route – retrieve words from a lexicon Phonological route – sound out words

33 Neuropsychology studying Alexia Phonological route Group word into syllables (by vowels/consonants) Convert syllables to proper phonemes Evident in children sounding words Some patients have difficulty pronouncing unfamiliar words Example: non-words like troat Otherwise no problem reading Phonological deficit hypothesis Lexical route Identify base root: antiabortion anti-abort-ion Access Lexical memory to recall proper pronunciation of parts Some patients have difficulty accessing lexicon Must pronounce out word Difficulty with exceptions: yacht, come, have Dyseidetic or visual dyslexia

34 Neuropsychology is Difficult Usually have a dodgy cognitive model of a process Must find a match between this and multiple possible brain implementations Evidence from patients who have suffered damage difficult… Damage can affect many areas Patients often on medication with not entirely clear effects Patients grouped together with same damage often different Example: Trauma and tumour quite different Imaging Scans have limited accuracy Patients age very relevant One solution: case study with individuals

35 Relationship With Artificial Neural Networks ANN typically leave out many aspects of real networks Real neurons generate sequences of action potentials Frequency and phase significant (ANN has a simple number output) Real networks have multiple neurotransmitters Many distinct types of neurons with different shapes (ANN has one type) Real networks have microcircuits Compute complex nonlinear functions (ANN usually a sum) Maybe synapse should be unit rather than neuron Some success: trained a network to recognise object position relative to eye direction Used hidden layer in ANN Resulting values closely resembled measurements from macaque monkey neurons

36 Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Looking at the Science Engineering vs. Science Introduction to Cognitive Science Cognitive Psychology 1 Cognitive Psychology 2 Cognitive Development Linguistics Neuroscience Philosophy


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