Exam 3: Neuroprosthetics & Brain Machine Interface

Question 1

Degrees of freedom:

Answer 1

This describes the number of independent ways in which
something can change. A joystick has 2 degrees of freedom, left-right and up-down. If
you add a button to the joystick, you add another degree of freedom, button pressed-
not pressed.

Question 2

Neuroprosthetic control signals from muscles vs cortex:

Answer 2

Muscles provide a strong signal
that can be recorded non-invasively. If a patient has control of ANY muscles at all, you
can train those muscles to control a prosthetic device. People can learn to use the small neck muscles right behind their ears to control a device. With current technology, the
only time a patient should receive a cortical implant for neuroprosthetic control is if
they are essentially “locked-in” and unable to move any muscles in their body. Don’t
stick stuff in your brain unless you absolutely need to.

Question 3

Closing the loop:

Answer 3

A critical component to controlling a prosthetic is receiving feedback
about the operation. For most devices, this is limited to visual feedback, but new cutting-
edge devices are trying to use sensors in the prosthetic to drive electrical stimulation
that activates either the patient’s nerves or their cortical neurons, giving them a sense
of somatosensation and/or proprioception to assist prosthetic control.