Pre-stimulus endogenous activity modulates category tuning and influences behavior Yuanning Li 1,2,3 , Michael Ward 3 , R. Mark Richardson 2,3 , Max G’Sell 4 , Avniel Singh Ghuman 2,3 1 Joint PhD program in Neural Computation and Machine Learning, Carnegie Mellon University 2 Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh 3 Dept. of Neurological Surgery, University of Pittsburgh 4 Dept. of Statistics and Data Science, Carnegie Mellon University
Perception depends on not only the input 1/14
Perception depends on not only the input but also the ongoing endogenous activity in the brain 1/14
Perception depends on not only the input but also the ongoing endogenous activity in the brain The mechanism by which endogenous activity modulates perception is unknown 1/14
Endogenous activity correlates to po post-st stim activity and perceptual behavior Behavioral perception Endogenous activity Arieli et al., 1996; Kisley and Gerstein, 1999; Evoked Basar, 1980; Brandt et al., 1991; response Nikulin et al., 2007;Henriksson et al., 2015 2/14
Endogenous activity correlates to post-stim activity and pe perceptua ual be beha havior Thut et al., 2006; Busch et al., 2009; Behavioral VanRullen et al., 2011; Ng et al., 2012; perception Henry et al., 2012, 2014; Kayser et al., 2016 Endogenous activity Evoked response 2/14
Endogenous activity correlates to post-stim activity and perceptual behavior • It is not clear if the endogenous activity modulates neural tuning to affect perception. Behavioral perception ? Endogenous activity Evoked response 2/14
Experiments • Intracranial Electroencephalography (iEEG) • Total number subjects: 30 (Photo Credit: Adeen Flinker) 3/14
Experiments • Task: • 6 categories (faces, bodies, words, houses, tools, scrambled non-objects) • 1-back task to detect repetitions + + + + + 3/14
Experiments • Category-selective electrodes: 246 • faces, bodies, words, houses, tools, scrambled non- objects R L 3/14
Questions • Does pre-stimulus activity modulate the degree of category tuning in response to visual stimuli? 4/14
Questions • Does pre-stimulus activity modulate the degree of category tuning in response to visual stimuli? • If so, does the same aspect in pre-stimulus activity that modulates tuning also predict behavioral perception? 4/14
Pre-stimulus activity as proxy for ongoing endogenous activity ! = ' #() + + #,-. + /′ "#$% ! "#$% stim-onset time 5/14
Pre-stimulus activity as proxy for ongoing endogenous activity ! = ' #() + + #,-. + /′ "#$% ! "#$% stim-onset time 5/14
Pre-stimulus activity as proxy for ongoing endogenous activity ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 5/14
What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 5/14
What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 5/14
What about category tuning? ! = ' #() + ' %"# + +′ "#$% ! "#$% stim-onset time 5/14
How does pre-stimulus activity modulate category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 5/14
How does pre-stimulus activity modulate category tuning? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 5/14
Train a classifier using only the posterior activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 5/14
Fix the posterior discriminant component ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 5/14
Conditioning on the pre-stimulus activity ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 7 0+8/ stim-onset time 5/14
Trial-by-trial metric of category-tuning ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) • Define: # 4 * +,- - (post-stimulus) category tuning • 6/14
Trial-by-trial metric of pre-stimulus modulation ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) • Define: # 4 * +,- - (post-stimulus) category tuning • 5 4 * /0+ - (pre-stimulus) modulation index (MI) • 6/14
Trial-by-trial metric of pre-stimulus modulation ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) ? behavior • Define: # 4 * +,- - (post-stimulus) category tuning • 5 4 * /0+ - (pre-stimulus) modulation index (MI) • 6/14
Does the inclusion of pre-stimulus activity improve categorical classification accuracy? 1.5 sensitivity index (d') 1 0.5 0 bodies faces words tools places scrambled 7/14
Does the inclusion of pre-stimulus activity improve categorical classification accuracy? *** evoked only 1.5 evoked + endogenous * *** *** sensitivity index (d') *** 1 ** 0.5 * p < 0.05 ** p < 0.01 *** p < 0.001 Paired t-test 0 bodies faces words tools places scrambled 7/14
Does the inclusion of pre-stimulus activity improve categorical classification accuracy? • YES. Conditioning on pre-stimulus activity functionally improves category classification. *** evoked only 1.5 evoked + endogenous * *** *** sensitivity index (d') *** 1 ** 0.5 * p < 0.05 ** p < 0.01 *** p < 0.001 Paired t-test 0 bodies faces words tools places scrambled 7/14
Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? 700 high MI low MI Reaction time (ms) 650 600 Preferred category Non-preferred category Preferred Non-preferred 8/14
Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? n.s. * 700 high MI low MI Reaction time (ms) 650 * p < 0.05 600 Permutation test Preferred category Non-preferred category Preferred Non-preferred 8/14
Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? n.s. * 700 high MI low MI Reaction time (ms) 650 * p < 0.05 600 Permutation test Preferred category Non-preferred category Preferred Non-preferred 8/14
Does the sa same e asp spec ects ts of pre-st stimulus activity also correlate with behavior performance? • YES. The same aspects in pre-stimulus activity that influences post-stimulus category tuning also predict perceptual behavior performance. n.s. * 700 high MI low MI Reaction time (ms) 650 * p < 0.05 600 Permutation test Preferred category Non-preferred category Preferred Non-preferred 8/14
Main questions • Does pre-stimulus activity modulate the degree of category tuning in response to visual stimuli? YES • If so, does the same aspect in pre-stimulus activity that modulates tuning also predict behavioral perception? YES 9/14
What are the pre-stimulus features that contributing to the modulation? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) 10/14
What are the pre-stimulus features that contributing to the modulation? ! "#$%&'() * +,- , * /0+ = 2(# 4 * +,- , 5 4 * /0+ ) Phase Broadband power Event-related potential 0.25 0.05 0.05 0.2 0.04 0.04 Prob. of non-zero Prob. of non-zero Prob. of non-zero 0.15 0.03 0.03 0.1 0.02 0.02 0.05 0.01 0.01 0 0 0 0 50 100 150 -500 -400 -300 -200 -100 -500 -400 -300 -200 -100 Freq. (Hz) Time (ms) Time (ms) 10/14
What are the pre-stimulus features that contributing to the modulation? • Phase around 15-30 Hz demonstrated consistent pattern. Phase Broadband power Event-related potential 0.25 0.05 0.05 0.2 0.04 0.04 Prob. of non-zero Prob. of non-zero Prob. of non-zero 0.15 0.03 0.03 0.1 0.02 0.02 0.05 0.01 0.01 0 0 0 0 50 100 150 -500 -400 -300 -200 -100 -500 -400 -300 -200 -100 Freq. (Hz) Time (ms) Time (ms) 10/14
What’s the nature of the pre-stimulus modulation? • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? 11/14
What’s the nature of the pre-stimulus modulation? • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? Significant cross-electrode correlation? 11/14
What’s the nature of the pre-stimulus modulation? • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? * 0.15 Mean (abs) corr. coeff. * Significant cross-electrode 0.1 n.s. correlation? 0.05 0 same category diff. category 11/14
What’s the nature of the pre-stimulus modulation? • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? * 0.15 Mean (abs) corr. coeff. * Significant cross-electrode 0.1 n.s. correlation? It is restricted to neural 0.05 circuits of the same category-selectivity. 0 same category diff. category 11/14
What’s the nature of the pre-stimulus modulation? • A reflection of fluctuations in global cognitive state (e.g. arousal/attention)? • A reflection of infra-slow fluctuations seen in resting state? 12/14
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