the opposite of attention is epilepsy: six ways of thinking about attention and why you should

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  • Slide 1
  • The Opposite of Attention is Epilepsy: Six ways of thinking about attention and why you should
  • Slide 2
  • Everyone Knows What Attention Is Everyone knows what attention is. It is the taking possession by the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought...It implies withdrawal from some things in order to deal effectively with others William James
  • Slide 3
  • Everyone Knows What Attention Is James definition is a good start toward operationalizing attention What we would call selective attention As distinct from arousal alerting cognitive effort
  • Slide 4
  • Everyone Knows What Attention Is The goal of this talk: Give you some conceptual handholds to start thinking about attention Tell you my (and my labs) line of thinking about attention
  • Slide 5
  • Everyone Knows What Attention Is Preview: 1.Attention solves the philosophical problem of a unitary consciousness 2.Attention solves a metabolic and thermal engineering problem 3.Attention solves a signal-to-noise problem by filtering noise 4.Attention solves a signal-to-noise problem by boosting signal gain 5.Attention solves a problem of ambiguity 6.Attention solves a network complexity problem
  • Slide 6
  • Everyone Knows What Attention Is Notice that none of these ideas are exclusive of any others They are all compatible ways to conceptualize the same phenomenon
  • Slide 7
  • Attention Solves a Philosophical Problem Unitary Consciousness We are each one conscious self Attention is the phenomenological manifestation of this constraint You only get one train of thought Maybe attention is epiphenomenal If you are a neurophilosopher, this is why you should think about attention.
  • Slide 8
  • Attention Solves an Engineering Problem Waste heat is both an applied and theoretical characteristic of computation The human brain is metabolically demanding The cortex is a thermal engineering nightmare If you design microprocessors, this is why you should think about attention.
  • Slide 9
  • Attention Solves a Signal-to-Noise Problem by Filtering Noise capacity limit or sensory bottleneck notion first proposed by Donald Broadbent in the 60s leaky filter notion proposed by Anne Treismann in the 70s
  • Slide 10
  • Attention Solves a Signal-to-Noise Problem by Filtering Noise Evidence: Selective attention acts as a gate to awareness Simons & Levin If you do cognitive psychology (or neurophilosophy), this is why you should think about attention.
  • Slide 11
  • Attention Solves a Signal-to-Noise Problem by Filtering Noise What are the neural correlates of such gating?
  • Slide 12
  • Attention Solves a Signal-to-Noise Problem by Filtering Noise Chelazzi et al. Evidence: Selective attention suppresses neurons representing task- irrelevant features or objects Note that search array always contains a good stimulus for the recorded cell but that might not be the target
  • Slide 13
  • Intracranial Recordings of Attentional Selection Initial response of cells is classical
  • Slide 14
  • Intracranial Recordings of Attentional Selection Initial response of cells is classical Response during delay maintains a representation of the target feature
  • Slide 15
  • Intracranial Recordings of Attentional Selection Initial response of cells is classical Response during delay represents the target feature Initial response to search array is classical
  • Slide 16
  • Intracranial Recordings of Attentional Selection About 200 ms after array onset, response of cell begins to depend on attention Response becomes more vigorous if cell is tuned to features of the target (i.e. the selected stimulus) Response becomes suppressed if cell is tuned to a non-target distractor If you do electrophysiology: This is why you should think about attention! (note this effect is absent in anesthetized animals)
  • Slide 17
  • Attention Solves a Signal-to-Noise Problem by Boosting Signal Gain Evidence: responses are faster and more accurate (memory !) for attended relative to unattended events If youre a cognitive psychologist, this is why you should think about attention (and probably you already do).
  • Slide 18
  • Attention Solves a Signal-to-Noise Problem by Boosting Signal Gain Evidence: Event-Related Potentials are enhanced for attended relative to unattended stimuli If you do electrophysiology, this is why you should think about attention.
  • Slide 19
  • Attention Solves an Ambiguity Problem Sensory Input Ambiguity Cell tuned to red. Should it fire? Area V4 Receptive field = ~4 deg visual angle
  • Slide 20
  • Attention Solves an Ambiguity Problem Sensory Input Ambiguity Cell tuned to red. Should it fire? Area V4 Receptive field = ~4 deg visual angle If you do computational neuroscience, This is why you should think about attention.
  • Slide 21
  • Attention Solves an Ambiguity Problem Response Mapping Ambiguity (e.g. Stroop Task) Cell tuned to line orientation. Should it affect your response? Area V4 Receptive field = ~4 deg visual angle If you do computational neuroscience, This is why you should think about attention. B L U E
  • Slide 22
  • Attention Solves an Ambiguity Problem Reward mapping ambiguity Cell tuned to red. Should it be associated with reward? Area V4 Receptive field = ~4 deg visual angle If you do computational neuroscience, This is why you should think about attention.
  • Slide 23
  • Attention Solves a Network Complexity Problem The brain is a massively interconnected network - each neuron makes ~ 1000 connections Gordon Kindlmann & Andrew Alexander University of Wisconsin Van Essen, Andersen & Felleman (1992)
  • Slide 24
  • Attention Solves a Network Complexity Problem On the time scale of behaviour, the network is anatomically hard-wired Fast functional reconfiguration
  • Slide 25
  • Attention Solves a Network Complexity Problem Point to the red horizontal line
  • Slide 26
  • Attention Solves a Network Complexity Problem Point to the red horizontal line Visual stimulus drives visual neurons Black Brain Box Motor plan is executed
  • Slide 27
  • Attention Solves a Network Complexity Problem Point to the red horizontal line Visual stimulus drives visual neurons Black Brain Box Motor plan is executed
  • Slide 28
  • Attention Solves a Network Complexity Problem Point to the red horizontal line Notice the mapping is selective:
  • Slide 29
  • Attention Solves a Network Complexity Problem Point to the red horizontal line Notice the mapping is selective:
  • Slide 30
  • Attention Solves a Network Complexity Problem Now point to the green vertical line Notice the mapping is easily reconfigured
  • Slide 31
  • Attention Solves a Network Complexity Problem
  • Slide 32
  • Thus sensory neurons are in some sense omnipotent each ones contribution to cognitive and motor networks is not determined by anatomical connectivity it is determined dynamically by some control system
  • Slide 33
  • Attention Solves a Network Complexity Problem Notice this is an extension of the binding problem Cells representing features of the same objects must contribute to a reconstituted whole object representation These cells must be bound to all the other cells mediating the current cognitive or motor behaviour If you study the connectome, this is why you should think about attention.
  • Slide 34
  • Attention Solves a Network Complexity Problem The brain is a massively interconnected network - each neuron makes ~ 1000 connections
  • Slide 35
  • Attention Solves a Network Complexity Problem The brain is a massively interconnected network - each neuron makes ~ 1000 connections X 1000
  • Slide 36
  • Attention Solves a Network Complexity Problem The brain is a massively interconnected network - each neuron makes ~ 1000 connections X 1000
  • Slide 37
  • Attention Solves a Network Complexity Problem The brain is a massively interconnected network - each neuron makes ~ 1000 connections X 1000
  • Slide 38
  • Attention Solves a Network Complexity Problem Crude Analogy By 4 synapses the tree comprises more than 10 Billion cells! Attention prevents runaway connectivity: Clearly the brain must have a system by which information is routed appropriately through the network
  • Slide 39
  • Attention Solves a Network Complexity Problem What does runaway connectivity look like? Heres a hint: the feed forward sweep of signal following a visual event is relatively unconstrained by attention Red = earliest response at this latency Yellow = has already responded Lamme (2000) By ~115 ms post-stimulus, much of the cortex has responded to the visual event
  • Slide 40
  • Attention Solves a Network Complexity Problem What would be the consequence if attention did not select cell assemblies? Neural Gridlock? Maybe not the right concept.
  • Slide 41
  • Attention Solves a Network Complexity Problem The brain is a system of coupled oscillators Driving such systems can trigger unexpected synchronization
  • Slide 42
  • Attention Solves a Network Complexity Problem Classic Example of spontaneous synchronization
  • Slide 43
  • Attention Solves a Network Complexity Problem See a fabulous TED talk about synchronization by Steven Strogatz at: www.ted.com/talks/steven_strogatz_on_sync.html
  • Slide 44
  • Attention Solves a Network Complexity Problem Do brains exhibit runaway global synchronization? Yes, this is characteristic of certain kinds of epileptic seizures. 3 Hz Spike and Wave EEG pattern during absence seizure
  • Slide 45
  • Attention Solves a Network Complexity Problem OK so how might a brain solve this problem? How might the attention system facilitate a dominant cell assembly and suppress others? Neuronal communication through neuronal coherence - Pascal Fries, TINS (2005)
  • Slide 46
  • Attention Solves a Network Complexity Problem Individual oscillators coupled to a central oscillator
  • Slide 47
  • Attention Solves a Network Complexity Problem Role of the central oscillator has been called the dominant network Communication-through-coherence suggests that oscillations within cell assemblies become phase locked One set of such assemblies achieves global dominance by having their individual phases nudged into coherence
  • Slide 48
  • Thanks To my lab past, present and future: Greg Christie Andrew Butcher Jarrod Dowdall Karla Ponjavic Scott Oberg Dillon Hambrook Amanda McMullen Sheena McInnes Aja Mason