Neurosensory System

7/28/2019 Neurosensory System

1/30

Avian Sensory Systems

Sensory world similar to ours, that of other

primates, primarily visual

Are some subtle and some significant

differences

Senses of birds are NOT well understood


2/30


3/30

Vision

In most species, primary sense used to

locate, identify and obtain food Primary sense in predator detection

Important in flight, displays

(communication)

Map of world is visual


4/30


5/30

Key Structural Components of

the Avian Eye

Lens: focuses light on retina

Retina: image-forming region

Pectin: supplies O2, nutrients to retina

(a significant difference)


6/30


7/30


8/30

Visual acuity of birds is NOT

well understood Cones more dense: +

Flat eyes: - (some have round eyes)

Each cone has own nerve fiber: + Steep fovea magnifies image: +

Steep fovea distorts image: -

Guess: most birds slightly better than us, afew much better


9/30

Other Features of Avian Vision

Steep fovea enables birds to follow moving

objects well (pursuit of prey)

Eyes located on side of head, many birdshave only one fovea per eye, lack binocular

vision, lack depth perception

Birds have a wide field of view (3000+common, up to 3600 in Woodcock)


10/30


11/30

Binocular vision of owls: 2 fovea

per eye, eyes located in front


12/30

More Features

Species with 2nd fovea (located inside edge

of the eye) have binocular vision (raptors,

aerial hawkers)

Color vision NOT well understood due to

presence of oil droplets

Richer, see ultraviolet

See better through glare, at dawn

Detect polarized light


13/30

One more feature: better

accommodation due to musclesworking on lens and cornea


14/30

Hearing: Total range of

frequencies heard by birdssimilar to us, but each bird

species has narrower range

Species hear best the frequencies of

their own calls and song


15/30


16/30


17/30

Ear Structure

No external flap, rim around openingamplifies sound in species hunt by sound

Ear drum separates outer, middle ear (likeus), single bone in middle ear transferssound to inner ear (3 bones in us)

3 fluid-filled canals for balance next tomiddle ear

Sound receptors in cochlea of inner ear


18/30


19/30

Features of Avian Cochlea

More dense sensory hairs suggest moresensitivity (types determine frequencies

heard, number stimulated determinesintensity perceived)

Tissue as well as fluid above sensory hairssuggests better temporal resolution, ability

to detect complexities of song

Experimental tests do not support


20/30

Owls and harriers use sound to

locate prey

Rims around earopenings amplifysound

Round heads collectsound

Asymmetric ears (both

horizontally andvertically) enablelocalization of sound


21/30

Echolocation

Occurs in 2 families, oilbirds and cave swiftlets Low frequency sounds (clicks) enable

orientation in dark caves
http://img.ebigchina.com/cdimg/108482/131342/0/1036015646.jpg


22/30

Birds have olfactory organ, but

sense smell NOT well understood Turkey vultures, tubenoses,

honeyguides use locate food

Some tubenoses use to locate burrows Kiwis use to detect food underground

Use unknown in most species


23/30

Birds have taste buds, but use ofsense of taste NOT well

understood

Birds use vision or touch, not taste,

to identify food


24/30

Sense of touch (tactile)

Herbst (and other) corpuscles aremechanoreceptors

Located on filoplumes, bristles

Located on bills (especially probers),

tongues (woodpeckers) of some speciesfor prey detection


25/30

Other senses of birds

Magnetic sense

Sensitive to changes in barometric pressure

Hear infrasound (super-long wavelengths)

All are foreign to us, used in migration


26/30


27/30

Features of Avian Brain

Large optic lobes, small olfactory lobes

Large cerebellum

Site of higher learning centers, complex

neural processing is corpus striatum (middle

cerebrum), not cerebral cortex (outer

cerebrum) Left hemisphere dominance


28/30


29/30

The Control System

Consists of nervous and hormonal systems

Elements of the hormonal system: adrenal,

thyroid and pituitary glands and the gonads Hypothalamus (midbrain) controls the

hormonal system

Neurosecretions act on adjacent pituitaryHormones from pituitary control other

glands


30/30

Avian intelligence

Many birds have complex social memories,aware of relationships to others (cooperative

breeders, other social species) Some birds have well developed spatial

memories, can remember thousands oflocations (corvids, chickadees; parrots)

Parrots demonstrate cognitive abstractreasoning, semantic signaling (others?)

Neurosensory System

Documents

Transcript of Neurosensory System