Record electrical activity from the scalp and compare eyes-open and eyes-closed conditions. Look for an alpha rhythm, then examine how signal quality and variation affect what you can conclude.
EEG measures the combined activity of millions of cortical neurons through electrodes placed on the scalp. Hans Berger, intrigued by a near-death incident that spurred thoughts of telepathy, discovered these rhythms in the 1920s. He noticed they change when eyes open or close. You will test for a difference between conditions and consider what the recording can establish.
Changes during thinking tasks are exploratory observations. This recording does not identify a thought, emotion, or stress level; movement and electrode contact can also change the trace.
Materials:
Setup & Procedure:
Materials: Same kit as above.
Setup & Procedure:
Compare marked eyes-open and eyes-closed intervals. Look for changes in the alpha band, about 8–13 Hz, while checking for eye movement, muscle activity, and poor electrode contact. Count peaks per second and compare amplitude where a rhythm is visible. A clear increase is not visible in every participant or recording. Report what you observed, including little or no change.
Draw the visual pathway and mark the occipital electrode positions. Explain why this location is useful for the comparison, while recognizing that one scalp channel cannot identify the activity of a single brain area or reveal a person’s thoughts.
Cortex as an organized neuronal system, observed directly.
MS-LS1-8 Gather and synthesize information that sensory receptors respond to stimuli by sending messages to the brain for immediate behavior or storage as memories.
HS-LS1-2 Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
2 Developing and Using Models
Draw the visual pathway from the eyes to the visual cortex, mark where the headband sat, and use it to explain the change.
3 Planning and Carrying Out Investigations
Record EEG from the forehead and over the occipital lobe, alternating eyes open and closed.
4 Analyzing and Interpreting Data
Compare the traces and see alpha waves strengthen with eyes closed.
5 Using Mathematics and Computational Thinking
Count peaks per second and measure amplitude.
6 Constructing Explanations and Designing Solutions
Discuss what the alpha change says about how engaged the visual cortex is.
Cause and Effect
Eye closure boosts alpha.
Structure and Function
Visual-cortex location explains the signal.
LS1.D Information Processing
The brain integrates sensory input.
LS1.A Structure and Function
Cortical organization.
Performance expectations, crosscutting concepts and core ideas from Hands-On Neuroscience Curriculum Overview, Unit 3, module 3.1, whose core lab this is. The practices are the ones this page asks students to do.
