Bi/CNS/NB 150: Neuroscience

November 9, 2015

THE AUDITORY SYSTEM

Ralph Adolphs

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Chapter 30 & 31Auditory System(Adolphs)

The auditory systemAnatomy: the ear, the brainstem, auditory cortexDetails of middle ear, cochlea, transductionAudition is tonotopic (a map of the cochlea)Spatial audition requires making comparisons between the two earsTopography: there are centrally synthesized maps of auditory spaceThere are special model systems (songbirds, owls, and bats)

Nov. 9 (today)

Chapter 22: pp. 475-480, 491-495Chapter 23: pp. 498-504, 510-521Chapter 24: 530-535, 541-553

Somatosensory System(Adolphs)

Somatosensory systemThere are many different kinds of touch/pain receptors and channelsThere are distinct spinal cord pathways for touch and painTouch is somatotopic (a map of the body surface)Pain is represented in distributed brain regionsPain can be modulated, for instance by endogenous opioids

Nov. 11

Discussion section

Sensory systems Nov. 12

Chapter 65,66,67Learning & Memory(Adolphs)

Learning and MemoryThere are multiple memory systems: declarative and nondeclarativeThere are stages of memory: encoding, consolidation, retrievalThere are multiple physiological mechanisms implementing memoryThere are specific brain systems for different kinds of memory

Nov. 13

We emphasize these points from Kandel in Bi/CNS 150

Read Lecture

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Sherrington (1948): senses classified as

--teloreceptive (vision, hearing)

--proprioceptive (limb position)

--exteroceptive (touch)

--chemoreceptive (smell and taste)

--interoceptive (visceral)

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Anatomy of the auditory system-peripheral-central

Language

Model systems

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Stages of Processing

1. Transduction2. Perception (early)3. Recognition (late perception)4. Memory (association)5. Judgment (valuation, preference)6. Planning (goal formation)7. Action

SensationKnowledge

BeliefDecision

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Similarities between audition and vision

Processing streamsTopographic maps

Distortion/magnificationPerception is inferential

Perception makes comparisonsCan be driven in the absence of sensory input

Plastic periods in developmentImportant role in social communication

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Differences between audition and vision

Audition Vision

Transduction

Temporal Acuity

Spatial Acuity

Feedback

Active sense

Specializations

Receptor Numb.

Fast Slow

High Low

Low High

To cochlea not to retina

Somewhat Very

Language Faces

16k 100M

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WHAT IS HEARING?

to know what is where by listening

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Human listeners can:

--accurately judge the location of a sound and can tell the difference between sounds separated by a few degrees

--discriminate between two frequencies separated by 1-2 Hz over a range of nearly 10 Octaves

--discriminate between sounds with intensity differences of 1-2 dB over a range of 10^8

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Peripheral auditory system:--external and middle ears and auditory nerve

Central auditory system:brainstem, midbrain, and forebrain levels

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Based on the properties of the basilar membrane, high frequency

sounds localize to the cochlea base and low frequency sounds to the

cochlea apex.

The Traveling Wave

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Fibers in the 8th Nerve-95% from inner hair cells-~5% from outer hair cells- Olivocochlear bundle

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Neural code:

-Rate-Timing-Place

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MNTB – Medial Nucleus of the Trapezoid Body

- Inhibitory projections to the LSO

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Wernicke’s Area(left primarily)

BA 22

Temporal Visual

Association Areas

Temporal pole

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Primary Auditory CortexBA 41, 42

Insula (notpart of Temporal

Lobe)

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The Auditory Cortex

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3 Model systems

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Copyright © The McGraw-Hill Companies. All rights reserved.

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Copyright © The McGraw-Hill Companies. All rights reserved.

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