5 Senses

1. Vision

2. Audition (hearing)

3. Gustation (taste)

4. Olfaction (smell)

5. Somatosensation (touch)

2. Audition 

3. Gustation 

 Topographical organization = like a map

o Not every part of your body is equally represented in your somatic cortex

what occupies large parts of somatic sensory cortex 

 o Hands, mouth and genitals

(more sensitive)

o Gyrus = high

o Sulcus = low 

o Central Sulcus 

o Motor cortex

= in ear

o Tympanic Membrane (eardrum) 

o Ossicles – middle ear bones

 middle ear bones

There are three: hammer, anvil, and stirrup

There are three: hammer, anvil, and stirrup

ear 

    a receptor organ that focuses sound waves on the nervous system

o   Receptors are the interface with our world 

cochlea - inner ear

( These are called cilia (hair cells) that flow along in a fluid

        Cranial/Spinal Nerves

 There are 31 spiral nerves throughout the back

o   All information received from the body is.... 

sensory info goes were 

How many cranial nerves are there 

o   12 cranial nerves

*Signals that reach the cranial nerves are lead to the brainstem and then thalamus

Signals that reach the cranial nerves go where? 

  auditory sensory information is routed to temporal lobes.

A tonotopic organization is found within the auditory

cortex; neurons are arranged by frequency (from low to

high) and each are specific to a level of frequency

is found within the auditory

cortex; neurons are arranged by frequency (from low to

high) and each are specific to a level of frequency

Vision

·        Light/photons

(particles of light)=environmental energy

Electromagnetic spectrum

   different colors of light correspond to different

wavelengths on the spectrum

When we experience color....

we experience the wavelength of light corresponding

to that color

Visible light spectrum

are the light waves humans can see;

ROY G BIV=

red,

orange,

yellow,

green,

blue,

indigo

violet

How do we pick up the light?

With our eyes!

    The Eye

cornea

Clear covering of eye

1. light first hits the cornea

Misshaped cornea

stigmatism

where is the aqueous humor and what does it contain 

Behind the cornea is a chamber filled with a fluid

aqueous humor

water-like liquid

 Fluid helps with the flow of nutrients into the eye and shapes the eye

Behind the chamber with aqueous humor

Iris

  colored portion of the eye

it is a muscle that spirally opens/closes

Function: to determine how much light enters the eye

 iris spirals down (pupil contracts) because

there is sufficient amount of light

surrounding you

          pupils dilate

                                           the lens

   the lens

part of the eye that is responsible for focusing light waves

on the of the eye

Muscles are found at the corners of lens; adjust lens to

better focus on light waves

another fluid chamber called vitreous humor

another fluid chamber

  Carries nutrients to the eye and maintains its shape

to the retina

Retina is found behind the lens as well.

On retina are photoreceptors

2

The rods and Cones

Rods

are much more numerous (about 120 million) 

* allow you to see in dim light (black and white).

o   Cones

are less numerous (about 6-7 million)

allow you to see in color.

They are focusing photoreceptors; high acuity.

   Located in the center of retina (fovea)

  If you see something from the corner of your eye...

Eyes of cats and dogs

o   Dogs and cats don’t have cones, only rods. Thus, they are very sensitive to lowlight conditions

 tapetum

 a membrane found in back of the eye that is reflective

(light is reflected back to photoreceptors).

 Glow in dogs’ eyes is due to an adaptation called...

   Light/Dark Adaptation: Example

Ex. Dark Adaptation: you run into a dark theater and initially cannot see the people or the seats

§  Ex. Light Adaptation: wake up with bright light surrounding you. Eyes hurt because you’re forcing your retina to adjust too quickly

light to dark adoptaions

- cones

adapt more quickly but are less sensitive

light to dark adoptation

Rods

more sensitive but adapt at a slower rate;

once rods have fully adapted, you can see

well in the dark

Overall, eyes are conditioned for sun coming up/down

(light appearing/disappearing) gradually

 cells are the final output neurons of the vertebrate

retina.

Relationship between gallion cells and cones?

Cones are more acute because they have a 1:1

relationship with ganglion cells

low sensitivity due to low convergence)

  Rods are more sensitive because they have

greater convergence ledaing to action

potential

  Ganglion cells have axons that join together to make a tract

 lies   Behind retina 

*  place where axons of ganglion cells leave the eye to go to the optic nerve.

There are no photoreceptors here=blind spot

Retina >Optic Nerve> Brain

      Eye to Brain:

Optic Chiasm

X-shaped; half of fibers from one retina go to one side of

the brain while the other remaining fibers go to the other side

  Eye to Brain

Temporal Retina:

axons stay on the same side of the brain and go to the

thalamus of the same side

       Eye to Brain:

Nasal Retina

axons crossover

o   Nasal Retina

o   Functional significance of this?

  All information from left visual field end up in the right hemisphere

All information from right visual field

cross over to the left hemisphere

             optic tract

       releases neurotransmitters to thalamus (group of nuclei)

where does the send axons   Thalamus (LGN)

sends axon to occipital lobe (back of brain) to the

primary visual cortex

                            LNG

primary relay center that serves the visual center in the  

thalamus

    Color Vision thories

1. Trichromatic Theory

2. Opponent-Process Theory

who was the Trichromatic Theory by?

Young& von Helmholtz

explains the 3 photoreceptors

  We can see in color because we have 3 receptors (hence “trichromatic”) that are sensitive to a particular color. These are blue, green and red, all of which are cones.

If you see something blue, amount of

blue receptors in eye is greater than

red receptors. If we see purple,

amount of blue and red receptors are

both high

Opponent-Process Theory

   explains the ganglion cells, thalamus and

primary visual cortex

Different receptors in visual system form

antagonistic pairs; one cone is excited while

the other is inhibited