Segregation and integration of cortical laminar information streams and their role in attention. Andre Moraes Bastos July 30 th, 2014 ICON, Brisbane

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1 Segregation and integration of cortical laminar information streams and their role in attention Andre Moraes Bastos July 30 th, 2014 ICON, Brisbane

2 Introduction Top-down and bottom-up processing Cognitive distinction ( endogenous vs. exogenous ) Anatomical distinction ( feedforward vs. feedback ) These asymmetries define a cortical hierarchy Points to a key computational challenge of cortical networks: functional segregation and functional integration What is the putative role of distinct cortical laminae in these processes?

3 Cortical lamina in monkey area V1 L1 L2/3 4A/B 4Ca/B L5 L6 WM

4 Anatomy of hierarchy Henry Kennedy et al.

5 Feedforward and feedback counterstreams define a cortical hierarchy Markov et al., Science 2013

6 Spike-field coherence Spike-field coherence Gamma synchronization is superficial, beta synchronization is deep Buffalo et al., (2011)

7 Hypothesis for strong anatomical asymmetries Gamma Lower Area Higher Area Beta Prediction: strong functional asymmetry between gamma and beta

8 Hypothesis for weak anatomical asymmetries Gamma/beta Lower Area Higher Area Beta/gamma Prediction: weak functional asymmetry between gamma and beta

9 Monkey 2 Monkey 1 Increasing hierarchical level Coverage of large-scale, high-density monkey ECoG recordings 7A 8M TEO DP V4 8L V2 V1

10 Visual attention task

11 Measuring directed influences with Granger causality A + - AR model used to predict A t+1 based on the past terms of A B - if past terms of B can improve prediction of A t+1 compared to prediction from past terms of A alone B granger-causes A Spectral GC fraction of total power at a frequency f of A is G-caused by B

12 Quantifying functional asymmetries Bastos, Vezoli, Bosman, et al., BioArchive

13 Anatomy of hierarchy Henry Kennedy et al.

14 Correlation between anatomical and functional graded asymmetries Bastos, Vezoli, Bosman, et al., BioArchive

15 Correlation between anatomical and functional asymmetries DAI(frequency) = GC outflow GC inflow GC outflow+gc inflow SLN = # neurons labeled supragranular #neurons labeled infra+supragranular

16 Graded-ness of anatomy and function are correlated Bastos, Vezoli, Bosman, et al., BioArchive

17 The functional visual cortical hierarchy Bastos, Vezoli, Bosman, et al., BioArchive

18 Comparing hierarchical models Functional Hierarchy Model Anatomical Hierarchy Model (Kennedy) R=0.94, p= Bastos, Vezoli, Bosman, et al., BioArchive

19 Attentional modulation of inter-areal GC influences *** significant (p<0.05) in both monkeys * significant (p<0.05) in one monkey only

20 Is the functional hierarchy dynamic? Bastos, Vezoli, Bosman, et al., BioArchive

21 Is the functional hierarchy dynamic? Bastos, Vezoli, Bosman, et al., BioArchive

22 Is the functional hierarchy dynamic? Bastos, Vezoli, Bosman, et al., BioArchive

23 Canonical microcircuits for predictive coding? Forward prediction error ( i 1) v ( i 1) v ( i 1) g Backward predictions () i v () i x Forward prediction error ( vi, ) () i v () i x () i v f () i () i x () i g Backward predictions Bastos et al., (2012)

24 Spectral asymmetries between superficial and deep cells ( i 1) ( ) v 2 superficial ( i 1) v () i v () i x x 10-4 frequency (Hz) 1 ( i) 2 ( i 1) 2 v ( ) ( ) 2 v () i v () i x 1 deep () i v () i x frequency (Hz) Bastos et al., 2012

25 Conclusions Feedforward and feedback anatomical connections are segregated in different layers Functionally, feedforward and feedback communication are segregated in different freqeuncies These communication rules define a functional hierarchy Beta and gamma influences are likely related to the underlying laminar anatomical connectivity and oscillatory profile of different areas Inter-areal synchronization at beta and gamma frequencies is enhanced with selective visual attention Changes in inter-areal GC influences over task periods reveal a dynamic functional hierarchy These patterns may underlie a basic circuit motif of canonical microcircuits

26 Acknowledgements Julien Vezoli Conrado Bosman Jan-Mathijs Schoffelen Robert Oostenveld Henry Kennedy Pascal Fries

27 Future questions If top-down and bottom-up processing are segregated in layers and frequencies, then what mechanism(s) mediate their functional integration? Cross-frequency interactions: how does topdown beta lead to bottom-up gamma modulation? Cortical hierarchical organization in the human brain?

28 The hierarchy has some intrinsic variability Markov et al. (2014)

29 Original Communication-throughcoherence hypothesis Fries 2005

30 Theta and gamma are feedforward, beta is feedback Bastos, Vezoli, Bosman, et al., BioArchive

31 Inter-areal synchronization exists predominantly at non-zero phase Jia et al., 2013 Grothe et al., 2012 Gregoriou et al., 2009

32 Original Communication-throughcoherence hypothesis Fries 2005

33 CTC through frequency and anatomical segregation Bastos, Vezoli, Fries, in preparation

34 CTC through frequency and anatomical segregation Bastos, Vezoli, Fries, in preparation

35 Markov et al., J Comp Neurol, 2013

Masters research projects. 1. Adapting Granger causality for use on EEG data.

Masters research projects. 1. Adapting Granger causality for use on EEG data. Masters research projects 1. Adapting Granger causality for use on EEG data. Background. Granger causality is a concept introduced in the field of economy to determine which variables influence, or cause,