Raven spreads two sheets across the Windowsill. One is a table of the senses. The other is a map of the brain.
"Every row ends in the same place," she says. "What do you notice?"
Rocket scans the last column. "Brain, brain, brain, brain, brain."
"Now the map," Raven says. "The brain has regions. Each one handles different signals."
Nova hovers over the drawing. "Find the region that handles what you saw yesterday," she says, "and the one that stored the tray."
Rocket traces with his finger. "Back of the brain for seeing. Side of the brain for sound, and memory lives there too."
"Eighty-six billion cells," Raven reads from the bottom of the page. Rocket goes quiet.
The MedlinePlus medical encyclopedia, run by the National Library of Medicine, describes each sense. Here are its facts in one table.
Each sense receives information from the environment. The information is converted into nerve signals carried to the brain.
A certain amount of stimulation is required before you become aware of a sensation. This minimum level is called the threshold.
| Sense | Information it receives | Where the receptors are | Fact from the encyclopedia |
|---|---|---|---|
| Hearing | Sound | Inner ear | Vibrations cross the eardrum and are carried by the auditory nerve |
| Vision | Light | Retina | The retina converts light into a nerve signal for the optic nerve |
| Smell | Odors | Lining high in the nose | Smell and taste work together |
| Taste | Sweet, salty, sour, bitter, umami | About 10,000 taste buds | Most tastes are linked with odors |
| Touch | Pain, temperature, pressure, vibration, position | Skin, muscles, tendons, joints, organs | The brain interprets the type and amount |
The OpenStax textbook Concepts of Biology describes the regions of the brain. A human brain contains around 86 billion neurons, its signal cells.
The occipital lobe, at the back, is primarily involved in vision: seeing, recognizing and identifying the visual world.
The temporal lobe, at the base near the ears, processes and interprets sounds. It also contains the hippocampus, which processes memory formation.
The parietal lobe, at the top, processes touch sensations like pressure, pain, heat and cold, and the sense of body position.
The frontal lobe, over the eyes, contains the olfactory bulb, which processes smells. It also plans and carries out movement.
The cerebellum, at the base of the brain, controls balance and helps coordinate movement.
| Brain region | Where it sits | What it handles |
|---|---|---|
| Occipital lobe | Back of the brain | Vision |
| Temporal lobe | Base of the brain, near the ears | Sounds, and memory formation (hippocampus) |
| Parietal lobe | Top of the brain | Touch: pressure, pain, heat, cold, body position |
| Frontal lobe | Front, over the eyes | Smell (olfactory bulb), planning movement, attention |
| Cerebellum | Base of the brain | Balance and coordinating movement |
| Statement | True or false? |
|---|---|
| Every sense in the table sends its signals to the brain. | ? |
| The frontal lobe handles vision. | ? |
| Smell and taste work together. | ? |
| The cerebellum processes memory formation. | ? |
Excellent reading. Tomorrow you will see why senses matter for safety and memory in everyday life.