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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 cm 2 AS OPPOSED THAT OF HUMANS 2275 cm 2 .
  • 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) Lecture 4 (Prof. Scheifele) Presentation Transcript

  • 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 [email_address]
  •  
  • Central Nervous System
    • 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/ CSD 512 L1
  • 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 CSD 512 L1
  • Cerebral Cortex
    • SULCI – shallow groove or depression
    • FISSURE – a surface groove dividing and organ
    • GYRI – Convolution of the brain surface separated by sulci
    CSD 512 L1
  • cerebellum Temporal Frontal Parietal Occipital CSD 512 L1
  • 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 CSD 512 L1
  • More Gross Anatomy (Exterior) Supramarginal Gyrus Auditory Visual Somesthetic CSD 512 L1
  •  
  • Synaptic Vesicle Receptors Autoreceptors
  •  
  • CSD 512 L1
  • BRAINS OF VARIOUS ANIMALS 540 kg 10,000 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
  • Cranial Nerves CSD 512 L1
  • Cranial Nerves Images from: /www.med.umich.edu/lrc/coursepages/M1/anatomy/html/atlas/images/ CSD 512 L1
  • 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 CSD 512 L1
  • 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
  • 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
  • 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
  • Brain Comparison
  • Central Auditory Pathways Medulla Pons Thalamus MGB Inferior Colliculus Region of Cochlear Nucleus
  • 11/26/10 Neuroanatomy of the auditory system The cochlear nuclei 0
  • 11/26/10 Neuroanatomy of the auditory system TRAPEZOID BODY 0 The trapezoid body calculates interaural intensity differences
  • 11/26/10 Neuroanatomy of the auditory system LATERAL LEMNISCUS 0
  • 11/26/10 Neuroanatomy of the auditory system The inferior colliculus: processes sounds for auditory perception and reflex adjustments 0
  • 11/26/10 Neuroanatomy of the auditory system The brachium of the inferior colliculus and the medial geniculate nucleus 0
  • 11/26/10 Neuroanatomy of the auditory system 2 – inferior colliculus 18 – brachium of the inferior colliculus 21- medial geniculate body
  • 11/26/10 Neuroanatomy of the auditory system Transverse temporal gyri 0
  •  
  • SOME GROSS OBSERVATIONS
    • Large, unusually shaped
    • Well-fissured
    • Olfactory bulbs absent
    • Radical hypertrophy of acoustic areas
  • 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 .
  • Auditory Cortex
  • Cetacean Auditory Anatomy Image from: http://instruct1.cit.cornell.edu/courses/bionb424/students2004/kls36/neuroanatomy.htm
  • 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
  • Fini