Lecture 4 (Prof. Scheifele)

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  • 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-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.
  • 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)
  • Lecture 4 (Prof. Scheifele)

    1. 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
    2. 2. Central Nervous System 1. Consists of: spinal cord & brain spinal cord • conducts sensory information • conducts motor information The brain • receives sensory input from the spinal cord and cranial nerves • devotes most of its volume (and computational power) to processing its various sensory inputs and initiating appropriate — and coordinated — motor outputs. From: asymptotia.com/wp-images/2007/08/ 3CSD 512 L1
    3. 3. The Brain- by System • Reptilian brain • Limbic system • Neocortex From: spinwarp.ucsd.edu/NeuroWeb/Text/br-800epi.htm and http://www.ascd.org/portal/site/ascd/template.chapter/menuitem.b71d101a2f7c208cdeb3ffdb62108a0c/? chapterMgmtId=effbcba5ddcaff00VgnVCM1000003d01a8c0RCRD From: http://www.crystalinks.com/reptilianbrain.html 4CSD 512 L1
    4. 4. Cerebral Cortex • SULCI – shallow groove or depression • FISSURE – a surface groove dividing and organ • GYRI – Convolution of the brain surface separated by sulci 5CSD 512 L1
    5. 5. cerebellum Temporal Frontal ParietalOccipital 6CSD 512 L1
    6. 6. The Cerebrum: Ascending auditory system from thalamic to cortex- or…Gray matter over white matter…What’s the matter? Deep-lying structures: Basal ganglia; amygdala; hippocampus 7CSD 512 L1
    7. 7. More Gross Anatomy (Exterior) Supramarginal Gyrus Auditory Visual Somesthetic 8CSD 512 L1
    8. 8. Synaptic Vesicle Receptors Autoreceptors
    9. 9. 12CSD 512 L1
    10. 10. BRAINS OF VARIOUS ANIMALS ANIMAL BRAIN WEIGHT (G) BRAIN WEIGHT BODY WEIGHT % BODY WT SPERM WHALE 7800 g 15 tons=30,000 pounds= 13500 kg 0.06 % ELEPHANT 6000 BOTTLE-NOSED DOLPHIN 1500 g 500 kg 0.3 % HUMAN ADULT 1300-1400 150 pounds= 68 kg=68000 g 2 % HORSE 532 CHIMPANZEE 420 HUMAN BABY 350 - 400 DOG (BEAGLE) 72 9 to 18 kg 0.5 % CAT 30 SQUIRREL 22 ALLIGATOR 8.4 250 kg 0.003 % OWL 2.2 RAT 2 400 gm 0.5 % TURTLE 0.3 VIPER 0.1 GREEN LIZARD 0.08 540 kg 10,000
    11. 11. Cranial Nerves 14CSD 512 L1
    12. 12. Cranial Nerves Images from: /www.med.umich.edu/lrc/coursepages/M1/anatomy/html/atlas/images/ 15CSD 512 L1
    13. 13. Classification of Nerves Divided into Sensory and Motor divisions Sensory (afferent) nerves Motor (efferent) nerves Mixed nerves Image from: www.merck.com/mmhe/sec06/ch077/ch077c.html 16CSD 512 L1
    14. 14. 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
    15. 15. 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
    16. 16. 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
    17. 17. Brain Comparison
    18. 18. Central Auditory Pathways Medulla Pons Thalamus MGB Inferior Colliculus Region of Cochlear Nucleus
    19. 19. 01/29/15 Neuroanatomy of the auditory system 22 The cochlear nuclei
    20. 20. 01/29/15 Neuroanatomy of the auditory system 23 TRAPEZOID BODY The trapezoid body calculates interaural intensity differences
    21. 21. 01/29/15 Neuroanatomy of the auditory system 24 LATERAL LEMNISCUS
    22. 22. 01/29/15 Neuroanatomy of the auditory system 25 The inferior colliculus: processes sounds for auditory perception and reflex adjustments
    23. 23. 01/29/15 Neuroanatomy of the auditory system 26 The brachium of the inferior colliculus and the medial geniculate nucleus
    24. 24. 01/29/15 Neuroanatomy of the auditory system 27 2 – inferior colliculus 18 – brachium of the inferior colliculus 21- medial geniculate body
    25. 25. 01/29/15 Neuroanatomy of the auditory system 28 Transverse temporal gyri
    26. 26. SOME GROSS OBSERVATIONS • Large, unusually shaped • Well-fissured • Olfactory bulbs absent • Radical hypertrophy of acoustic areas
    27. 27. 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.
    28. 28. Auditory Cortex
    29. 29. Cetacean Auditory Anatomy Image from: http://instruct1.cit.cornell.edu/courses/bionb424/students2004/kls36/neuroanatomy.htm
    30. 30. 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
    31. 31. Fini

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