1. Computational Neuroscience Lecture 7 Conor Houghton

2. PICTURE FROM WIKIPEDIA

3. The inner ear PICTURES FROM WIKIPEDIA COCHLEA CROSS SECTION OF THE COCHLEA

4. Outer hair cells amplify http://youtube.com/ /watch?v=Xo9bwQuYrRo Video of dancing haircell.

5. Inner hair cells signal http://youtube.com/ /watch?v= 1VmwHiRTdVc Video about the inner ear, with the sound removed.

6. Stereocilia of a frog’s inner ear PICTURE FROM WIKIPEDIA

7. Different hair cells respond to different frequencies – all hair cells respond to sound over a short time window.

8. This gives a windowed Fourier transform.

9. Windowed Fourier transform

10. s(t)

11. k(t)

12. s(t)k(t)

13. Weber’s law Roughly speaking – effect goes like the log of the cause. Sort of holds for the auditory system. Use log|S(k,t)| SMALL PRINT: The phase information is gone, however, we have overlapping windows and two variables; there are theorems that say we haven’t lost anything.

14. Spectrogram http://youtube.com/ /watch?v= 5hcKa86WJbg Zebra finch song and spectrogram.

15. Spectrogram http://youtube.com/ /watch?v= 5hcKa86WJbg Repeat of zebra finch song.

16. Zebra finches http://effieex3.tumblr.com/post/20369494508

17. Zebra finch brain

19. Maybe it’s like vision?

20. Linear model

21. Error

22. Minimize error

23. Calculate the STRF

24. From Sen et al. J Neuro 2001

25. From Sen et al. J Neuro 2001

26. From Sen et al. J Neuro 2001

27. So? Works better than you might expect, particularly in the lower part of the pathway. Does not give the whole story, particularly further up the pathway. The calculation is hairy, but seems to work, certainly don’t try to improve it. The STRFs aren’t quite as revealing as you’d expect.