CELL COMMUNICATION

Activity developed during the 2009 Exploratorium Summer Institute “Class Menagerie” by: Caltech Fellow Xoana Troncoso

and High School Teachers Patricia Dunlap, Robert Martin & Erick Roldan

Background

While driving in our cars, if we would like to know how fast we are going, we have the luxury of simply looking at the speedometer. There are clocks and calendars for time, thermometers for temperature, and scales to tell us exactly how much mass an object has. We live in a world of absolutes!

However at the cellular level things are not so convenient. Our cells don’t have the luxury of using tools as measuring devices, but they do have one very powerful resource: each other! All of our cells are in constant communication with each other; imagine a party where everyone is talking to everyone at the same time. Specialized cells in our brains called neurons communicate by firing electrical signals called action potentials. People have even discovered ways to listen in on these electrical conversations.

What scientists have discovered is that these specialized cells are only able to interpret data by constantly comparing values to each other. For example, the only way that your brain can tell that a piece of paper is white, is by having white sensing neurons and dark sensing neurons have an electrical conversation in which they compare their values.

UP - DOWN

Play the FALLS_loop.mov movie

What’s going on???

No movementRested neurons

Downward movementRested neurons

No movementTired DOWN neurons

No movementRested neurons

= > =

DOWN neurons

UP neurons

Compare UP &DOWN

We see…NO

movementDOWN

movement

<

UPmovement!!

NOmovement

Expansion - Contraction

No movementRested neurons

ContractionRested neurons

No movementTired CONTRACT

neurons

No movementRested neurons

= > =

CONTRACT neurons

EXPAND neurons

Compare CONTRACT & EXPAND

We see…NO

movement CONTRACTION

<

EXPANSION!!NO

movement

BRIGHT - DARK

GrayRested neurons

BrightRested neurons

GrayTired DARK neurons

GrayRested neurons

= > =

DARK neurons

BRIGHT neurons

Compare BRIGHT & DARK

We see…GRAY DARK

<

BRIGHT GRAY

COLOR

Which colors does the brain compare?

When the image is…

Red

Blue

Green

Yellow

the after image is…

Greenish

Yellowish

Reddish

Bluish

REDRested neurons

BLANKTired RED neurons

BLANKRested neurons

> =

RED neurons

GREEN neurons

Compare RED & GREEN

We see…RED

<

GREEN!! BLANK

Try your to designyour own afterimage!

CELL COMMUNICATION

Activity developed during the 2009 Exploratorium Summer Institute “Class Menagerie” by: Caltech Fellow Xoana Troncoso

and High School Teachers Patricia Dunlap, Robert Martin & Erick Roldan