Brain Computer Interface

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Brain Computer Interface
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The Dream

• Controlling the physical world with our thoughts
  has always been the stuff of science fiction and
  dreams.
• In todays world, small demonstrations of such
  feats abound.
• Commercial BCIs
• Commercial headsets for gaming
• NeuroSky
• Emotiv EPOC

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Sensing the Brain

• EEG
• measures the electrical signals produced by nerve
  cells in your brain
• fMRI
• Detects blood flow in the brain to identify areas
  of activity a blood-oxygen-level-dependent
  (BOLD) signal.
• NIRS
• Detects near IR light absorption to identify
  areas of activity, another BOLD signal.
• Others
• CAT scan
• PET
• phMRI
• TMS

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Early Efforts
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Brain Imaging
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Animal brains

• Brain stem - controls the reflexes and automatic
  functions.
• Cerebellum - coordinates limb movements.
• Hypothalamus and pituitary gland - controls body
  temperature and behavioral responses such as
  feeding, drinking, sexual response, aggression
  and pleasure.
• Cerebrum - integrates information from all of the
  sense organs, initiates motor functions, controls
  emotions and holds memory and thought processes.

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Cerebral Cortex

• Parietal Lobe - involved in the reception and
  processing of sensory information from the
  body.Frontal Lobe - involved with
  decision-making, problem solving, and
  planning.Occipital Lobe - involved with
  vision.Temporal Lobe - involved with memory,
  emotion, hearing, and language.

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Somatosensory Motor Cortex
Somatosensory
Motor
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Your Electric Brain

• Brains are filled with neurons.
• Each neuron receives electrical inputs from about
  1000 other neurons.
• Impulses are added together leading to generation
  of an electrical discharge called an action
  potential.
• electric signals (i.e., action potentials) zip
  from neuron to neuron as fast as 250 mph

• Neurons communicate at structures called
  synapses.
• Information moves around the brain via electrical
  activity but communication between neurons is
  chemical.

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EEG

• An EEG records electrical signals from the brain
• Measures postsynaptic potentials of neurons, via
  electrodes on the scalp

• An EEG detects the summed ionic currents of
  thousands of pyramidal neurons beneath each
  electrode.

• The signals relayed to the EEG are typically
  amplified 10,000 times and filtered.

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Brain Wave Types

• EEGs record brain waves which are oscillating
  electrical voltages in the brain measuring a few
  millivolts.
• There are six widely recognized brain waves
• Delta 1-4 Hz.
• Theta 4-7 Hz.
• Alpha 8-12 Hz.
• Mu rhythm is alpha-range activity that is seen
  over the sensorimotor cortex.
• Beta12-30 Hz.
• Gamma 30100 Hz.

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BCI Inputs

• Slow cortical activation
• Mu and Beta rhythms
• performance of different cognitive tasks
• imagination of movement of different parts of the
  body
• Steady-state evoked potential the response of
  the brain to a constant stimulus, in which the
  brain activity has the same frequency as the
  stimulating frequency
• visually evoked P300 potential oddball
  response

Training
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Electrode Placement