November 10, 2015

Direct brain state modulation by close-loop feedback


Neurofeedback techniques are rapidly becoming established as effective treatment for various neuropathologies. In traditional neurofeedback protocols participants are shown a representation of their current brain activity guided by which they subsequently attempt to influence various frequency components. Training patients to suppress alpha frequency power has been shown to effective for treatment of ADHD [1]  and similar techniques have been used to  improve concentration, [2]. In this project we will explore an alternate protocol where we construct neurofeedback directly from  brain activity, circumventing a participants active involvement. Practically we will explore the feasibility that closed-loop interaction between high luminance LED and brain activity reported by EEG can arbitrarily modulate alpha frequency power across the occipital cortex.  This project will be a  collaboration with the Center for Computational Neuroscience and Robotics and Sackler Center for Consciousness science.

Recently theoretical and experimental work by Dr Buckley of the Centre for Computational Neuroscience and Robotics (CCNR)  has demonstrated  in primates the  feasibility of modulation brian dynamics by implementing real-time closed-loop visual feedback [3]. The goal of this project will be to investigate the feasibility of this human participants utilizing EEG.

It is already well  established  that exposing human participants to 10Hz high luminance visual flashes increase EEG alpha frequency (~10Hz) in visual areas [4]. Our  protocol represents  a novel modification whereby the sequence of visual flashing is derived directly from real-time EEG recordings of the participants brian. To implement we will first construct a pair of  visual stimuli goggles,  which contain high luminance (30000 lumens)  LED’s in each lense holder. We will then import  real-time EEG data into Matlab and use the same software to control the sequence of visual flashes. The participant will then be asked to where these goggle and close their eyes after which we we will deliver various flashing visual stimuli. Each EEG experiment will involve three different conditions. .

  • Standard flicker: Where participants are shown 10hz flashing stimulus. This will be used to validate our basic experimental setup.
  • Phase Reversal:  A 10 Hz flashing signal is presented but the phases of the signal will be intermittently shifted by half a cycle. This will attempt to validate the idea that brain activity is dependent on the moment-to-moment activity of the visual stimulus.
  • Flicker Feedback Suppression: The  visual  flashes are triggered when the raw EEG signal goes below a certain negative threshold.
  • Flicker Feedback Enhancement:  The  visual  flashes are triggered when the raw EEG signal goes above a certain positive threshold,

This project will involve a significant technological component involving the development of both novel hardware and software. It will also involve conducting human  EEG trials over summer under the supervision of Dr  Schwartzman. The significant research milestone are enumerated below.

Hardware and Software

  1. Develop protocol for streaming EEG data into software in real-time, this shoudl be possible using existing EEG equipment i and an off-the shelf Matlab plugin called Field Trip []. We will attempt reducing latencies wherever we can.
  2. Constructing the high luminance LED goggles set with 30000 lumens white LEDS and cables.
  3. Interfacing Matlab with the LED goggles via  National Instrument  Labjack board enabling us to digitally manipulate the LED flicker from the software.
  4. Using the real-time EEG stream to modulate the output flashing sequences of the LED’s

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