Test Oct. 21 Review Session Oct 19 2pm in TH201 (that’s here)

Test Oct. 21 Test will cover everything including vision (i.e. including the lecture on Friday Oct. 9 th )

Attention Controlling how information flows through the brain

The Theory Is… Be able to complete this sentence by Nov 20 – This means you’ve completed some background reading including some primary literature – You’ve put lots of thought into crafting a testable, focused theory and predictions that follow from that theory

Early Selection Early Selection model postulated that attention acted as a strict gate at the lowest levels of sensory processing Based on concept of a limited capacity bottleneck

Late Selection Late Selection models postulated that attention acted on later processing stages (not sensory)

Electrophysiological Investigations of Attention

Modulation of Auditory Pathways Hillyard et al. (1960s) showed attention effects in human auditory pathway using ERP Selective listening task using headphones – Every few minutes the attended side was reversed – Thus they could measure the brain response to identical stimuli when attended or unattended beep beep beep beep boop beep beep beep beep boop beep beep attending LEFT Ignoring RIGHT

Modulation of Auditory Pathways Result: ERP elicited by attended and unattended stimuli diverges by about 90ms post stimulus – Long before response is made – Probably in primary or nearby auditory cortex

Modulation of Auditory Pathways Other groups have found ERP modulation even earlier – as early as Brainstem Auditory Response Probably no robust modulation as low as cochlea by ~40 ms, feed forward sweep is already well into auditory and associated cortex – Thus ERP effects may reflect recurrent rather than feed forward processes

Modulation of Auditory Pathways Different ways to use attention in space beep beep beep beep boop beep beep beep beep boop beep beep attending LEFT Ignoring RIGHT beep beep beep beep boop beep now left, now right, now left, now right beep beep beep boop beep beep SUSTAINEDTRANSIENT

Modulation of Auditory Pathways Response times are faster for attended relative to unattended targets The theory is that transient and sustained attention act on auditory pathways the same way beep beep beep beep boop beep now left, now right, now left, now right beep beep beep boop beep beep TRANSIENT

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone BEEP

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone BEEP

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone BEEP

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Three speakers – Steady stream of tones – Respond to each tone BEEP

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – We can compare targets preceded by targets at the same location with targets preceded by targets on the other side

Modulation of Auditory Pathways Transient Attention: The Target-Target Paradigm – Does transient attention modulate auditory system like sustained attention?

Modulation of Auditory Pathways ERP is markedly different in the two situations! Tata et al. (2001) CZ Tata, Prime, McDonald, & Ward (2001) Tata et al. (2001) - +

Modulation of Auditory Pathways ERP is markedly different in the two situations! One possibility: – sustained attention allows for attentional configuration of sensory cortex to modulate feed- forward sweep but… – Transient attention can only modulate recurrent processes

Moran and Desimone (1985) “Classical” RF prediction: there should be no difference in responses in these two conditions Intracranial Recordings of Attentional Selection

Moran and Desimone (1985) Result: Intracranial Recordings of Attentional Selection “effective” stimulus at attended location – attention spotlight has selected object with features to which this neuron is tuned Response to Target “effective” stimulus at unattended location – attention spotlight has selected object with features to which this neuron is not tuned Response to “Sample” Response to Target Response to “Sample”

Moran and Desimone (1985) Result: – Neuron responds vigorously only if its effective stimulus is attended – Interesting caveat: this only applies when there is an ineffective stimulus (to which the monkey attends) present in the V4 RF When the ineffective stimulus is outside of the cell’s RF, its responses are largely unmodulated Intracranial Recordings of Attentional Selection

Chellazi et al ( 1993) Neural Correlates of Visual Search – Monkey is trained in a delayed match-to-sample task Cue appears 1.5 seconds before search array Monkey saccades to target – “good” and “poor” stimuli are identified for each recorded neuron Intracranial Recordings of Attentional Selection

Note that monkey isn’t “pre-cued” to attend to a location – Only target features are known prior to choice array onset With this paradigm it is possible to measure cell activity during delay, during search, and after selection Note that search array always contains a “good” stimulus for the recorded cell – but that might not be the target

Intracranial Recordings of Attentional Selection Initial response of cells is “classical”

Intracranial Recordings of Attentional Selection Initial response of cells is “classical” Response during delay maintains a representation of the target feature

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”

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

Intracranial Recordings of Attentional Selection Conclusion: – Attentional selection of locations and/or objects has physiological correlates and consequences How does attention get to where it needs to go? – Next time: Attention Orienting