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Marine Mammal Bioacoustics: The Central Auditory System

Central Nervous System. Consists of: spinal cord

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Marine Mammal Bioacoustics: The Central Auditory System

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    1. Marine Mammal Bioacoustics: The Central Auditory System Peter M. Scheifele MDr, PhD, LCDR USN (Ret.) University of Cincinnati Communication Sciences and Disorders, Neuroaudiology Dept. University Medical Center scheifpr@uc.edu

    3. Central Nervous System 3 CSD 512 L1

    4. The Brain- by System Reptilian brain Limbic system Neocortex 4 CSD 512 L1

    5. Cerebral Cortex 5 CSD 512 L1

    6. 6 CSD 512 L1

    7. The Cerebrum: Ascending auditory system from thalamic to cortex- or…Gray matter over white matter…What’s the matter? 7 CSD 512 L1

    8. More Gross Anatomy (Exterior) 8 CSD 512 L1

    12. 12 CSD 512 L1

    14. Cranial Nerves 14 CSD 512 L1

    15. Cranial Nerves 15 CSD 512 L1

    16. Classification of Nerves 16 CSD 512 L1

    17. The Central Auditory Nervous System (CANS) Sound localization and lateralization Auditory discrimination Frequency discrimination Intensity discrimination Quality (timbre) Pattern recognition Temporal discrimination temporal resolution, temporal masking, temporal integration, temporal ordering Auditory performance in presence of competing signals Auditory performance in the presence of degraded signals

    18. Acoustical Roles of the Brain Processing of sound Localization Temporal discrimination Intensity discrimination Frequency discrimination Vocalization development Motor functions for vocalization Sound ordering and development Communication and maybe language

    19. Ear and Brain are BOTH Required for Hearing Brain is also tonotopically organized Brain performs acoustic processing functions Discrimination Localization Patternization Brain makes use of the processed sound Links to memory and understanding Fight or flight Language Vocalization links

    20. Brain Comparison

    22. 10/21/2011 Neuroanatomy of the auditory system 22

    23. 10/21/2011 Neuroanatomy of the auditory system 23

    24. 10/21/2011 Neuroanatomy of the auditory system 24

    25. 10/21/2011 Neuroanatomy of the auditory system 25

    26. 10/21/2011 Neuroanatomy of the auditory system 26

    27. 10/21/2011 Neuroanatomy of the auditory system 27

    28. 10/21/2011 Neuroanatomy of the auditory system 28

    30. SOME GROSS OBSERVATIONS Large, unusually shaped Well-fissured Olfactory bulbs absent Radical hypertrophy of acoustic areas 1- DUE TO COMPLETE ABSENCE OF THE OLFACTORY PORTIONS OFTHE BRAIN LATERO-LATERAL DEVELOPMENT HAS NOT OCCURRED ALONG WITH “TELSCOPING” OF THE SKULL. 2- BOTH BATS AND WHALES HAVE WELL-DIFFERENTIATED AMYGDALOID COMPLEXES. 3- ONLY BATS AND WHALES HAVE ACOUSTIC COLLICULI THAT ARE LARGER THAN OPTIC COLLICULI (OFTEN BY AS MUCH AS 3-4 TIMES. 4- IN CETACEANS THE DIFFERENTIATION AND GROWTH OF THE CEREBRAL CORTEX MAY BE DUE TO THE MASSIVE INFLOW OF INPUTS FROM THE WELL-DEVELOPED AUDITORY AND TRIGEMINAL SYSTEMS. 5- THE LOSS OF OLFACTIONARY SENSE APPARENTLY HAS BEEN COMPENSATED FOR BY DEVELOPMENT OF THE TRIGEMINAL APPARATUS. ODNOTOCETES EXCEED MAN, AND ALL OTHER GROUPS AS WELL, IN CONVOLUTEDNESS OF THE CEREBRAL CORTEX HOWEVER; THE CORTEX IS RELATIVELY THIN IN DOLPHINS (1.4mm IN Tt VERSUS 2.9mm IN MAN). TOTAL AVERAGE CORTEX VOLUME OF Tt IS OLY ABOUT 80% OF THAT OF MAN PLACING Tt BELOW MAN BUT ABOVE SUCH ANIMALS AS CHIMPANZEES. 7. AVERAGE CORTICAL SURFACE AREAS FOR Tt ARE 3745 cm2 AS OPPOSED THAT OF HUMANS 2275 cm2.1- DUE TO COMPLETE ABSENCE OF THE OLFACTORY PORTIONS OFTHE BRAIN LATERO-LATERAL DEVELOPMENT HAS NOT OCCURRED ALONG WITH “TELSCOPING” OF THE SKULL. 2- BOTH BATS AND WHALES HAVE WELL-DIFFERENTIATED AMYGDALOID COMPLEXES. 3- ONLY BATS AND WHALES HAVE ACOUSTIC COLLICULI THAT ARE LARGER THAN OPTIC COLLICULI (OFTEN BY AS MUCH AS 3-4 TIMES. 4- IN CETACEANS THE DIFFERENTIATION AND GROWTH OF THE CEREBRAL CORTEX MAY BE DUE TO THE MASSIVE INFLOW OF INPUTS FROM THE WELL-DEVELOPED AUDITORY AND TRIGEMINAL SYSTEMS. 5- THE LOSS OF OLFACTIONARY SENSE APPARENTLY HAS BEEN COMPENSATED FOR BY DEVELOPMENT OF THE TRIGEMINAL APPARATUS. ODNOTOCETES EXCEED MAN, AND ALL OTHER GROUPS AS WELL, IN CONVOLUTEDNESS OF THE CEREBRAL CORTEX HOWEVER; THE CORTEX IS RELATIVELY THIN IN DOLPHINS (1.4mm IN Tt VERSUS 2.9mm IN MAN). TOTAL AVERAGE CORTEX VOLUME OF Tt IS OLY ABOUT 80% OF THAT OF MAN PLACING Tt BELOW MAN BUT ABOVE SUCH ANIMALS AS CHIMPANZEES. 7. AVERAGE CORTICAL SURFACE AREAS FOR Tt ARE 3745 cm2 AS OPPOSED THAT OF HUMANS 2275 cm2.

    31. BRAIN STRUCTURES: Possible Neurological Meaning Is relative size of specific areas a definite expression of the importance of its principal function? Past slide preparations of non-perfused brains have given only limited data regarding architectural arrangements of the cortex. Recent advances in anesthesia have allowed brains to be perfused in situ for histoarchitectural studies. 1- we generally accept that the direction of specialization and/or relative development of each part of the brain is largely a function of the environmental demands placed on the animal for survival. 2- THE AQUATIC ENVIRNMENT HAS PLACED DRASTICALLY DIFFERENT SENSORIMOTOR REQUIREMENTS ON CETACEANS THAN THEIR TERRESTRIAL COUNTERPARTS. THESE DRAMATIC ANATOMIC AND FUNCTIONAL CHANGES ARE REFLECTED IN THE CENTRAL NERVOUS SYSTEM. 3- NOTE THAT FUNCTIONAL INTERPRETATIONS ARE STILL VERY SPECULATIVE.1- we generally accept that the direction of specialization and/or relative development of each part of the brain is largely a function of the environmental demands placed on the animal for survival. 2- THE AQUATIC ENVIRNMENT HAS PLACED DRASTICALLY DIFFERENT SENSORIMOTOR REQUIREMENTS ON CETACEANS THAN THEIR TERRESTRIAL COUNTERPARTS. THESE DRAMATIC ANATOMIC AND FUNCTIONAL CHANGES ARE REFLECTED IN THE CENTRAL NERVOUS SYSTEM. 3- NOTE THAT FUNCTIONAL INTERPRETATIONS ARE STILL VERY SPECULATIVE.

    32. Auditory Cortex

    33. Cetacean Auditory Anatomy Cross section through a dolphin's head at the level of the ear and auditory nerve. 3V = third ventricle; A = auditory nerve; AB = auditory bulla; C = cochlea; CC = corpus callosum; CEB = cerebellum; CVS = central venous sinus; H = cerebral hemisphere; HY = hyoid; IC = inferior colliculus; L = larynx; PAG = periaqueductal gray containing nucleus ellipticus. Image from Dolphin (2000) Cross section through a dolphin's head at the level of the ear and auditory nerve. 3V = third ventricle; A = auditory nerve; AB = auditory bulla; C = cochlea; CC = corpus callosum; CEB = cerebellum; CVS = central venous sinus; H = cerebral hemisphere; HY = hyoid; IC = inferior colliculus; L = larynx; PAG = periaqueductal gray containing nucleus ellipticus. Image from Dolphin (2000)

    34. Comparative Auditory Anatomy Auditory brainstem nuclei and corresponding fiber diameters much larger than human equivalents Auditory structures are also much larger in odontocetes than mysticetes

    35. Fini

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