Is It Actually My Choice To Not Title This Post?
Since last I wrote about the “Free Will” project, I have increased the volume of data I have to work with and I have organized it into an intuitive MATLAB database for efficient manipulation via a set of functions for monte carlo analysis, spectrogram generation, etc. I will be making this code available to the public soon. Additionally, the readiness potential was seen when the experiment was conducted with eyes open and fixed, rather than just when eyes were closed. Noise from eye blinks and movements proved to not corrupt the EEG signal enormously.
I also noticed that within the eyes-closed paradigm, a sharp increase in a small frequency band within the alpha range appeared to occur just after movement completion and sometimes up to a short time before the next movement was initiated. (Shown below) Such a discovery may be indicative that mu rhythms are being recorded, which are more thoroughly explained in Anusha’s introductory post. If this rhythm can be tracked in a paradigm of spontaneous movements with no timer or mental counting, it is possible that the disappearance of the mu rhythm could be utilized as one of the characteristic predictors of movement onset. To see these rhythms most clearly, I filtered the data between 5 and 15 Hz. To smooth out the readiness potential most clearly, an aggressive filter between 0.01 and 5 Hz is used. In applying both filters to the same dataset separately, I was able to find the readiness potential as well as what might be mu rhythms.
I’ve constructed an experiment which incorporates a wooden clock (shown below) whose revolutions can be tracked through the BYB software. This will allow people to see when their average decision was made with respect to movement initiation along the course of the readiness potential. A DC motor holding the clock hand is powered by a battery and has a speed which can be adjusted via a series potentiometer. A photoresistor is then placed under a hole in the clock located just beneath the 12. The photoresistor is supplied power via a USB cord connected to the computer. Upon every revolution, the hand of the clock blocks the light from entering the opening and a change in voltage can be interpreted by the spike recorder. Best results were achieved when a light was placed over the clock for greater contrast. The clock works smoothly and in the experiment, the participant is instructed to self-report decision time after completion of the movement. The position on the clock and subsequently the point in the recording can be found from this information. Unfortunately, a consistent issue encountered in this experiment is that the self-reported times tend to fall a short time after movement initiation (not possible). Thus, I will need to adjust the paradigm for more accurate results. A histogram of relative decision times is shown below, where positive values indicate a decision falling after movement initiation.
Moving forward, I plan to attach an accelerometer to the head as a means of comparing the readiness potential signal to the movement artifacts which arise from wrist flexion. This will allow for the presence of the readiness potential to be properly validated, discarding the possibility of erroneous results due to recording electrode motion. I am still searching for more predictors of motion across other brain regions including premotor and prefrontal areas, though the readiness potential and “mu rhythms” are a huge step in the right direction.
Fresh, organic, locally sourced meditation researchLast Friday, Backyard Brains once again opened our doors (even wider–they’re always open during business hours!) to our fellow and aspiring citizen scientists as a part of this year’s Ann Arbor Tech Trek! Dozens of local tech companies had their doors open to the public that evening and we, like our friends around town, had people streaming in from open to close! BYB has participated for the last few years, and it is always a hit.
For four hours on Friday afternoon, we were packed with people from all walks of life who were interested in learning about Backyard Brains and neuroscience! It was a day of education, outreach, and new connections. In the office, we demonstrated our classic, the Human to Human Interface, as well as The Claw, and we even helped people control Mario with their eye blinks!
Our Summer Fellows also got in on the action, presenting their work down in the Makerspace at All Hands Active. This was the first chance our fellows got to share their science with the community, letting people in on their secrets and experiment rigs. For example, Silkmoth Fellow Jess was running experiments on a cockroach antenna during Tech Trek: Some kids were watching when she used different odors to try to get a reaction in the antenna, as pictured below:
It was definitely a unique opportunity, full of its own trials. According to Mantis Shrimp Fellow Dan, “I was trying to collect behavioral data with the mantis shrimp while his implants were falling out, and people would come by who obligingly ooh-ed and ahh-ed at the prep and politely listened to my spiel about EMGs and the strike. I’ve never presented about my research while actively conducting it.”
Meet the Fellows, See the Projects
Catch up with our Fellows! Since our Fellowship started, each fellow has been hard at work on their summer research. Saw a cool project and you want to know more? Check out these posts introducing each Fellowship research track:
First Progress Reports:
If you’ve been dying for an update on what we’ve been researching, fret no more! Feast your eyes on our first batch of updates!
Second Progress Reports:
Science marches ever onward! The Fellows have kept plugging away on their research in between all the fun and games, and here are their newest updates!
The summer is winding down, and with it our Fellowship. While scientific exploration is never really finished, here are some wrap-ups from our Fellows on the projects they have devoted their inquiry to over the past weeks.
“You are not controlling the storm, and you are not lost in it. You are the storm.”
The previous quote originated in a book called Free Will by Sam Harris. I take it to loosely mean that we do not exert conscious control over our thoughts and actions (free will), though we do not live out our lives as mere puppets of fate serving a larger-than-life purpose (determinism). Perhaps we are the sum total of our thoughts and actions, which themselves are traces of information propagating through a complex network of biological structures that has adapted to all it has ever mediated. Demonstrating the ubiquity of the signal traces which accompany our actions can act as the first evidence that it is the nature of humans to meander stochastically through space and time and to perceive our own “free will” so as to feel a little bit better about ourselves.
Now where would one look for free will? It is my belief that the first place to look is the final stage in motor control for the brain: the Primary Motor Cortex. Attaching an electrode vaguely over the region of the motor cortex associated with arm movements, and subsequently initiating arm movements being recorded via electromyography (EMG), or electrical muscle recordings, offers a simplified paradigm for scoping out a “readiness potential.” This characteristic waveform is an artifact of movement initiation, and it is possible that once the onset of the readiness potential can be accurately detected, a machine learning algorithm could be used to classify the signal and subsequently alert a subject of their intention to make a movement prior to onset. My first step was to locate the readiness potential, and I believe that I have done so. My next step is to test a wide variety of classification systems, filters, and novel computational methods for predicting arm movements.
The above figure shows the average EEG signal across multiple trials aligned by the recorded onset of movement via EMG. Movement initiation is shown by a vertical bar at 0 seconds. The monte carlo test window of 95% confidence is shown in red. The EMG was recorded from the right wrist flexor with the ground wire connected to the medial epicondyle. The EEG was recorded from C3 on the left side of the head with the reference electrode placed below the base of the occiput and the ground placed on the left mastoid, behind the ear.
My name is Aaron and I like to hear myself talk too much. I have one more year of schooling until I obtain my BS in Bioengineering from the University of Pittsburgh. In my spare time, I’ll pretty much do anything as long as it’s fun and/or challenging and/or competitive. Such activities may include, but are not limited to: frisbee, soccer, piano, baseball, board/card games, Rocket League (ranked Diamond in Standard and Doubles), and eating a lot. Also, I enjoy a good conversation.
This is a picture of me (left), my siblings (all older), and my niece.
My project is actually a continuation of previous Fellow’s project back in 2016. I’m going to be expanding on Patrick’s work, so make sure to check out his blog posts for some background information!