Franz Gall publishes work on Phrenology — a now discredited
science for measuring brain capacities.
Phineas Gage has an iron rod blown into his brain during an
accident, and lives, with profound personality changes.
Wilhelm von Waldeyer coins the term neuron.
First lobotomy performed in the US.
Rapid Eye Movements (REM) discovered.
Roger Sperry awarded Nobel Prize in Physiology for his discoveries
in the functional specialization of the cerebral hemispheres.
FDA approves clinical trial of brain implant developed by
TABLE 1. Timeline of brain research milestones.
TABLE 2. Classification
of EEG patterns.
In 1972, Michael Crichton’s The
Terminal Man explored the use of a
brain implant to treat a patient
suffering from blackouts. The 1991 Star
Trek: The Next Generation episode The
Nth Degree had a crew member construct a holographic interface to con-
nect his brain to the ship’s computer.
Brain interfacing technology has
gone from science fiction to the real
world. Already there are many companies offering hardware and software
products for making the brain connection. Educational institutions are
are devising ways to
assist the differently-abled, and security
professionals are using
techniques to help
assess an individual’s
Figure 1. Invasive
Image courtesy of
A technique to measure brain
response to crime-relevant stimulus.
A system that uses feedback to send a
portion of the output signal back to
the input. The output influences what
the next output will be.
Electroencephalogram — patterns of
electrical brain activity that can
be sensed on the scalp. Also called
Process where an individual trains their
brain by watching their own EEG brainwaves. Also called brainwave training.
Galvanic Skin Response (GSR)
Changes in the electrical properties of
the skin due to anxiety or stress.
Invasive Brain Procedure
A brain sensor is medically inserted
into the body.
Memory and Encoding-Related
Response — a wavelike response generated by the brain during recognition.
One of billions of brain cells that
uses electrochemical signals for
Non-Invasive Brain Procedure
A brain sensor is attached externally.
A group of well-known brainwave
components that can be measured.
state of mind.
Searching on Yahoo! for the
words brain computer interface yields
over 770,000 web pages. Clearly, there
is a good deal of interest in this
subject and its related offshoots. A
brief history of milestones in brain
research are listed in Table 1.
The purpose of a brain-computer
interface is to tap into the electrical
signals that are generated by the
brain. Where do those signals come
from? There are hundreds of billions
of cells in the human brain, called
neurons, with a myriad number of
interconnections with each other. The
neurons communicate using electrochemicals called neurotransmitters.
Groups of neurons fire together to
control some action in the body (or
guide some other brain process).
The use of charged ions in the
chemical reactions accounts for the
electrical activity that can be measured and acted upon. The waveforms
generated by the brain (called brainwaves) are classified into several different categories, depending on what
the brain is doing. Each category has
its own frequency range and characteristics. Table 2 lists the brainwave
categories, which are also called EEG
waveforms or EEG patterns.
There are essentially two camps
in the BCI world: those that utilize
invasive brain technology and those
that use non-invasive technology. The
goal of both technologies is to sense
brainwaves. An invasive brain sensor
consists of one or more electrodes
surgically inserted under the scalp or
directly into the brain. Figure 1 shows
one type of invasive sensor, a
two-dimensional array measuring two
millimeters on each side, containing
100 miniature electrodes.
Note that brain implants are
used for long-term monitoring. A
non-invasive sensor is simply placed
onto the scalp (using an appropriate