olfactory bulb

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Chemoreceptors. Sensory Transduction. Photoreceptors. Mechanoreceptors. Olfactory bulb. Olfaction. Audition. Vision. Anatomy of the Retina. Direction of light. Pigment layer. Choroid layer. Direction of retinal visual processing. Sclera. Front of retina. Back of retina. - PowerPoint PPT Presentation

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Page 1: Olfactory bulb
Page 2: Olfactory bulb

Olfactorybulb

Olfaction

ChemoreceptorsPhotoreceptors

Vision

Mechanoreceptors

Audition

Sensory Transduction

Page 3: Olfactory bulb

Direction of light

Direction of retinal visual processing

Frontofretina

Fibers ofthe opticnerve

Ganglioncell

Amacrinecell

Bipolarcell

Cone Rod

Photoreceptorcells

Horizontalcell

Pigment layer

Choroid layer

Sclera

Backofretina

Anatomy of the Retina

Page 4: Olfactory bulb

Back of retina

Outersegment

Outersegment

Innersegment

Synapticterminal

Synapticterminal

Innersegment

Directionof

light

Cells ofpigment layer

Cone Rod

Discs

Mitochondria

Nuclei

Dendritesof bipolar

cells

Frontof retina

Phototransduction

Disc

Lightabsorption

Enzymes

OpsinRetinene

Rhodopsin in the dark:retinene in 11-cis form

(inactive)

Rhodopsin in the light:retinene changes shape

to all-trans form(active)

all-trans formof retinene

11-cis formof retinene

Page 5: Olfactory bulb

Activation of photopigment

Activation of transducin (G protein)Activates PDE

Decrease in cyclic GMP

Closure of Na+ channelsin outer segment

Membrane hyperpolarization(the receptor potential)

Takesplacein outersegment

(Absorption)

(Reaction cascade)

(Spreads to synaptic terminal)

Takesplacein synapticterminal

Takesplace

in retina

(Removal of inhibition)

(If of sufficient magnitude to bring ganglion cell to threshold)

Closure of Ca2+ channelsin synaptic terminal

Release of inhibitory transmitter

Bipolar cells disinhibited (or, in effect, excited)

Graded potential changein bipolar cell

Action potential in ganglion cell

Propagation of AP to visual cortex (occipital lobe)visual perception

LIGHT

High concentrationof cyclic GMP

Na+ channels openin outer segment

Membrane depolarization

Opens Ca2+ channelsin synaptic terminal

Release of inhibitorytransmitter

(inhibition)

Bipolar cells inhibited

No action potentialin cell ganglion cell

No action potentialpropagation tovisual cortex

Takes placeinretina

(Spreads to synaptic terminal)

Takes place

inouter

segment

Takesplace

insynapticterminal

DARK

Outersegment

Innersegment

Synapticterminal

Cells ofpigment layer

Cone Rod

Discs

Nuclei

Bipolardendrites

Front of retina

Page 6: Olfactory bulb

Rods versus Cones

Properties of Rod and Cone Vision

RODS CONES

100 M per retina 3 M per retina

Vision in shades of gray Color Vision

High Sensitivity Low Sensitivity

Low Acuity High Acuity

Night vision Day vision

Much convergence in retina Little convergence in retina

More numerous peripherally Concentrated in fovea

What about adaptation?

Page 7: Olfactory bulb

Color Vision

Page 8: Olfactory bulb

Anatomy of the Auditory System

Page 9: Olfactory bulb

The Middle Ear and

Cochlea

APEX: Wider, more flexible end of basilar membrane (vibrates best with low-freq)

BASE: Narrower, stiffer end of BM near oval window (vibrates best with hi-freq)

Page 10: Olfactory bulb

The Traveling Wave

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Page 11: Olfactory bulb

Outerhair cells

(Stereocilia)

Tectorial membrane

Inner hair cells

Nerve fibers

Supporting cell

Basilar membrane

The Organ of Corti

Page 12: Olfactory bulb

The Hair Cell Potential

Page 13: Olfactory bulb

Tympanic Membrane Vibrates

Ossicles Vibrate

Oval Window Vibrates

Fluid Movement within Cochlea

Basilar Membrane Vibrates

Takesplace

in ear

Closure of Ca2+ channelsin synaptic terminal

Graded potential changein hair cell

Action potentials generated in auditory nerve

Propagation of AP to auditory cortex (temporal lobe)

sound perception

SOUND WAVES

Hair cell stereocilia bend as the movement of the basilar membrane displaces them in relation to the overlying tectorial membrane in which they are embedded.

Graded potential changein bipolar cell

Vibration ofround window

Energy dissipates (no sound perception)

Page 14: Olfactory bulb

The Transduction Channel

Page 15: Olfactory bulb

What about Adaptation?

Page 16: Olfactory bulb

What about the Outer Hair Cells?

QuickTime™ and a decompressor

are needed to see this picture.QuickTime™ and a

decompressorare needed to see this picture.

Page 17: Olfactory bulb

What about the Outer Hair Cells?

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are needed to see this picture.

Page 18: Olfactory bulb

Cochlear Implants