1. a Model of the Avian Superior Olivary Nucleus Raúl Rodríguez Esteban Master Thesis Defense August 1, 2002 C omputational S ensorimotor S ystems L ab

2. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 How does the owl hunt in total darkness ? Comparing the sound cues of its ears Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002

3. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Objectives of the model In particular, its influence in the coincidence detection process Study the role of the Superior Olivary Nucleus (SON) in the auditory system of the avians

4. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Auditory circuitry NM NA Section of a chicken brainstem SON NL

5. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Sound localization in avians ITD: Azimuth (longitude) Interaural Time Difference (ITD) ILD: Elevation (latitude) Interaural Level Difference (ILD)

6. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Two pathways for two coordinates Sullivan and Konishi (1984) NA ILD pathway NM ITD pathway

7. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Nucleus Angularis (NA) NA NM NA Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Soares et al. (2001) Features: - Tonotopic organization - Anatomically, 4 kinds of cells Features: - Tonotopic organization - Anatomically, 4 kinds of cells

8. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 NM Features: - Physiologically, 5 kinds of cells Features: - Physiologically, 5 kinds of cells Nucleus Angularis (NA) NA Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 damped tonic Itonic III tonic II one-spike Soares et al. (2002)

9. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Nucleus Magnocellularis (NM) NA NM NA Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Features: - Tonotopic organization - Spherical soma with few dendrites Features: - Tonotopic organization - Spherical soma with few dendrites Phase locking

10. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 The ITD pathway NM NL Parks and Rubel (1975)

11. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Features: - Tonotopic organization - Bilateral dendrites with a length that depends on the frequency - Inputs that follow the Jeffress model Features: - Tonotopic organization - Bilateral dendrites with a length that depends on the frequency - Inputs that follow the Jeffress model Nucleus Laminaris (NL) NM Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 NM NL Coincidence Detection ‘AND gate’

12. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Nucleus Laminaris (NL) NM Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 NM NL Problems Bilateral summation

13. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Nucleus Laminaris (NL) NM Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 NM NL Problems Timing errors

14. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 The Superior Olivary Nucleus (SON) NM NL NA SON Yang et al. (1999) Excitatory Inhibitory

15. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Model proposal Banks and Sachs (1991) Yang et al. (1999)

16. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Electrical behavior of neurons Passive (Rall) Active (Hodgkin & Huxley) Every part of the cell can be approximated as a piece of cable (compartment) Branched areas can be simplified as much as we need The soma and the axon have gates that are opened at certain voltages These gates can be described mathematically

17. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Passive behavior Data recorded by Katrina Macleod Ball-and-stick model (Rall 1959, 1960)

18. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Active behavior Hodgkin and Huxley (1952) Data recorded by Katrina Macleod

19. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Model proposal lden=120  m dden=4.8  m laxon=40  m daxon=4.8  m dsoma=18  m

20. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 The SON model connected SON Connections not modeled NA Components modeled and unknown NL NM Model by Jonathan Z. Simon Sound Simon et al. (2001) Connections already studied Funabiki et al. (1998) Yang et al. (1999)

21. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Results: improvement of the coincidence detection in NL Reducing high frequency mistakes due to bilateral summation Increasing the discrimination ratio by reducing ‘good’ and mistaken spikes evenly These improvements occur only in certain cases

22. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Results: hypothesis about the heterogeneity of the SON Three studies talk about the anatomical and physiological heterogeneity of the SON cells (Takahashi and Konishi, 1988; Carr et al., 1989; Lachica et al., 1994) However, the most recent study declares homogeneity, although using a small sample (n=23) (Yang et al., 1999) Our model suggests that there is some kind of physiological or anatomical adaptation for different types of inputs

23. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Future work Assess the relationship between the NA and the SON Simulate heterogeneity in the SON cells Link the NM to the SON

24. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Acknowledgements Jonathan Simon Katrina Macleod Catherine Carr Daphne Soares Sridhar Kalluri Michael Burger Nichola O’Hara Hisham Abdalla Matt Cheely Timothy Horiuchi Rock Shi Jonathan Fritz Mounya El Hilali Nikolaos Kanlis And the rest of the NS Lab

25. Raúl Rodríguez Esteban Master Thesis Defense August 1st, 2002 Results: the parameters of the model