Neuroethology in Neuroscience or Why study an exotic animal

Transcription

1 Neuroethology in Neuroscience or Why study an exotic animal

2 Nobel prize in Physiology and Medicine 1973 Karl von Frisch Konrad Lorenz Nikolaas Tinbergen

3 for their discoveries concerning "organization and elicitation of individual and social behaviour patterns". Behaviour patterns become explicable when interpreted as the result of natural selection, analogous with anatomical and physiological characteristics. This year's prize winners hold a unique position in this field. They are the most eminent founders of a new science, called "the comparative study of behaviour" or "ethology" (from ethos = habit, manner). Their first discoveries were made on insects, fishes and birds, but the basal principles have proved to be applicable also on mammals, including man.

4 Nobel prize in Physiology and Medicine 1973 Karl von Frisch Konrad Lorenz Nikolaas Tinbergen

5 Ammophila the sand wasp

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7 Black headed gull

8 Niko Tinbergen s four questions? 1. How the behavior of the animal affects its survival and reproduction (function)? 2. By how the behavior is similar or different from behaviors in other species (phylogeny)? 3. How the behavior is shaped by the animal s own experiences (ontogeny)? 4. How the behavior is manifested at the physiological level (mechanism)?

9 Neuroethology as a sub-field in brain research A large variety of research models and a tendency to focus on esoteric animals and systems (specialized behaviors). Studying animals while ignoring the relevancy to humans. Studying the brain in the context of the animal s natural behavior. Top-down approach.

10 Archer fish Prof. Ronen Segev Ben-Gurion University

11 Neuroethology as a sub-field in brain research A large variety of research models and a tendency to focus on esoteric animals and systems (specialized behaviors). Studying animals while ignoring the relevancy to humans. Studying the brain in the context of the animal s natural behavior. Top-down approach.

12 דג חשמל נמוכי מתח Weakly electric fish Jamming avoidance response

13 Neuroethology as a sub-field in brain research A large variety of research models and a tendency to focus on esoteric animals and systems (specialized behaviors). Studying animals while ignoring the relevancy to humans. Studying the brain in the context of the animal s natural behavior. Top-down approach.

14 Place Cells 1.5 m

15 Neuroethology as a sub-field in brain research A large variety of research models and a tendency to focus on esoteric animals and systems (specialized behaviors). Studying animals while ignoring the relevancy to humans. Studying the brain in the context of the animal s natural behavior. Top-down approach.

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17 Some classical models in neuroethology

18 Neuroethology where to? The field is moving away from the neuroethological approach by focusing on rodent models and neglecting all other species. The field is moving towards neuroethology by studying directly the physiology of behavior and by addressing natural behaviors that are relevant to the mouse.

19 Sound localization Sensory maps plasticity and development Spatial attention Multisensory integration

20 Barn owls as model system for Facial ruff serves as a sound amplifier sound localization

21 Barn owls as model system for Facial ruff serves as a sound amplifier sound localization Asymmetric ears allow for an increased spatial resolution in the vertical plane

22 Barn owls as model system for Facial ruff serves as a sound amplifier sound localization Asymmetric ears allow for an increased spatial resolution in the vertical plane Comb-like structures at the leading edge of the wing reduce noise during flight

23 Barn owls as model system for Facial ruff serves as a sound amplifier sound localization Asymmetric ears allow for an increased spatial resolution in the vertical plane Comb-like structures at the leading edge of the wing reduce noise during flight Brain structures involved in the analysis of sound are enlarged

24 Performing a psychoacoustic experiment with an owl

25 Sound-localization with free-field stimuli

26 The auditory localization cues: ITD - horizontal ILD - vertical location producing ITD = 0 µsec location producing ITD = 100 µsec

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28 Precision of sound localization in barn owls may be as good as 3 deg which corresponds to 6-10 µs.

29 Action potential Postsynaptic potentials These signals are the language" of neural processing.

30 Durations of events Typical duration of action potential: 1ms Typical duration of post-synaptic potentials: 5-10 ms Precision of sound localization by interaural time difference: 6-10 µs What has to be explained is Factor of

31 The principle of phase locking as a means to conserve time Sinusoidal signal Presumed resulting postsynaptic potential Registered signal in computer Note that in this example the response always occurs at a phase of 180 degrees.

32 number of spikes Phase locking in the barn owl Phase locking can be measured by plotting spike arrival times with respect to the period of the stimulus tone. 5 khz Period 200 µs 9 khz Period 111 µs Stimulus phase in degrees Precision of phase locking is 35 µs at 5 khz (Koeppl (1997)).

33 Jefferess model (1948) A + N = A + i i c N c A i A c = N i N c ITD left ear Right ear

34 Delay lines

35 Does the brain computes ITDs as Jefferess suggested? Nucleus Laminaris / Medial Superior Olive - sites of binaural convergence

36 Anatomical evidence for Jeffress model

37 ITD curves in Nucleus Laminaris ITD (µs) Response Time (ms) ITD (µs)

38 SOUND LOCALIZATION GAZE CONTROL Forebrain Sensory/Association Areas Archistriatum (FEF) Thalamus Ovoidalis (MGN) Rotundus (Pulvinar) Midbrain Inferior Colliculus central n. Inferior Colliculus external n. Optic Tectum (SC) D R VLVp (LSO/DNLL) LAM (MSO) Brainstem Tegmentum left cochlear n. right cochlear n. Motor Nuclei for gaze control

39 +20 0 el -20 V ILD (db) Response L20 0 az R20 Response ITD (µs)

40 +20 0 el -20 V ILD (db) L20 0 az R20 Response ITD (µs)

41 Visual and auditory maps in the OT

42 Computational map Transducing sound to action-potentials Computing auditory localization cues Integrating cues from specific locations Associating with external space Sound Frequency Intensity Time Side of ear Space tuned Frequency Binaural localization cues

43 Computational maps The matching problem location producing ITD = 0 µsec location producing ITD = 100 µsec

44 Computational maps The matching problem location producing ITD = 0 µsec location producing ITD = 100 µsec

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46 Normal Immediate Effect of Prisms Prism-adapted Knudsen and Knudsen J Neurosci (1989)

47 Effect of prism experience on auditory tuning Normal Immediate effect of prisms el A V A V -20 L20 0 az R20 Knudsen and Brainard, Science (1991)

48 Effect of prism experience on auditory tuning Normal Immediate effect of prisms After 8 weeks of prism experience el A V A V A V -20 L20 0 az R20

49 Quantification of learning 1. Behavioral test 2. Physiological test

50 Decline in learning with age 6 7. Knudsen, E. I..Science.( 1998)

51 Increased capacity for learning in adults that have had appropriate experience as juveniles 6 7. Knudsen, E. I..Science.( 1998)

52 Effects of juvenile experience on adult learning 6 7. Knudsen, E. I..Science.( 1998)

53 Incremental learning

54 Incremental learning Linkenhoker and Knudsen (2002) Nature

55 Rich and lively experiences increase learning capacity in adults Bergan et al., Journal of Neuroscience (2005)

56 Summary Decline in learning with age Increased capacity for learning in adults that have had appropriate experience as juveniles Incremental training improves learning Rich and lively experiences increase learning capacity in adults

57 Where is the site of plasticity? Forebrain Sensory/Association Areas Archistriatum (FEF) Thalamus Ovoidalis (MGN) Rotundus (Pulvinar) Midbrain Inferior Colliculus central n. Inferior Colliculus external n. Optic Tectum (SC) VLVp (LSO/DNLL) LAM (MSO) Brainstem Tegmentum left cochlear n. right cochlear n. Motor Nuclei for gaze control

58 Horizontal section through the tectal lobe Visual input from Retina and Forebrain c 0 0 r 0 0 ICC ICX 40 0 OT r m l c

59 Site of plasticity in the ICX Debello et al., J. Neurosci. 2001

60 After prism learning Visual input from Retina and Forebrain c 20 0 r 20 0 ICC ICX 60 0 OT r m c l

61 The instructive signal - Operates in the ICX - Visually based

62 Where is the instructive signal coming from?

63 BDA injection site in ICX 250 µm

64 Topography of the OT-ICX projection Layer 8 BDA FG r l

65 Restricted lesion of the optic tectum r l 500 µm

66 How can a visually based instructive signal act in an auditory structure?

67 Horizontal section through the tectal lobe Visual input from Retina and Forebrain c 0 0 r 0 0 ICC ICX 40 0 OT r m l c

68 bicuculline recording 0 iontophoresis barrels 0 recording barrel rec bic 500 µm ICC ICX OT µsec m r c l

69 Light responses in the ICX

70 Visual Receptive Fields in the ICX

71 ICX OT

72 ICX OT

73 0 µm bic -150 µm ICX -300 µm OT -450 µm -600 µm

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75 Properties of visual responses in ICX - Arrive from the OT - Display spatially restricted visual receptive fields - Form a map of space - Align with auditory spatial representation

76 Model gate ITD 1 Visual Input ITD 2 Visual Input ITD 3 ITD 1 Visual Input Auditory Input ITD 2 ITD 3 ITD 1 Visual Input Visual Input ITD 2 Visual Input ITD 3 ICX Optic Tectum

77 Bimodal Stimulus light right ear left ear

78 Visual and auditory interactions in the ICX auditory ITD visual auditory + visual

79 Average ITD (µs) AV-A (spikes) 6 AV-A (spikes) Post stimulus time (ms) ITD (µs)

80 Bimodal stimulus Normal Visual input ICC ICX OT

81 Bimodal stimulus Normal With prisms Visual input Visual input ICC ICX OT ICC ICX OT

82 Bimodal stimulus Normal With prisms Visual input Visual input ICC ICX OT ICC ICX OT

83 Summary An inhibitory gate controls the flow of visual information into the auditory system

84 Summary An inhibitory gate controls the flow of visual information into the auditory system The visual signals are appropriate to serve as the instructive signal for auditory plasticity

85 Eric Knudsen Daniel Feldman Michael Brainard Will Debello Peter Hyde Brie Linkenhoker Joe Bergan Stanford University Hermann Wagner - AACHEN University