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Posts tagged “experiment

Day #150: Surgery update

Well I’m alive, despite the VA’s best efforts. I’m struggling with some serious nausea to the point of vomiting, which has never happened to me before. I’m also in a lot of pain, but that was expected. In any case, start to finish (start as in the operating room and finish as in getting home so +30 minutes or so to the actual finish time) it took ~9 hours total good times for everyone. Anywho, I feel like death so I’ll write more later.


Day #149: An auspicious start

Brain

Well we did an experiment. I wish I could talk more about what we did, how we did, and why we did. Alas, I cannot. So instead, let’s talk about the vague how it went metric as in, maybe we found something maybe we didn’t, also this experiment highlights several quarks between the my school lab and the clinical lab.

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Day #148: Experimental design

 

EEGCap

Today is day one of ten for the time that I have to do some experiments. It’s an awkward time for sure, I mean surgery, school, etc. However, that’s just the way things work in academia, I actually had a break, so I’m ready to go to be honest. Which really means this isn’t horrible timing. I’ve already discussed the million things going on these weeks, but let’s talk about what goes into experiments, really.

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Day #143: Meeting with my two PI’s

Exo

Some of our exoskeletons from the lab

Today was an interesting set of events. I had my meeting with my two PI’s (which I still think would make a hilarious television show). The meeting went well, I’m very excited, but I’m also getting ready to be very, VERY busy. Let’s breakdown how it went shall we?

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Day #142: So you want to record from the brain…

EEG setup

My college helping me set up for the experiment I just did. This is how we add gel to the head, there is a tiny hole by each sensor, we then insert a blunt tip needle (we do NOT puncture the skin!) to add the gel between the sensor and the top of the head to eliminate the air gap caused by the hair. Unfortunately it looks scary, but we need something tiny to get around the sensor (if you look close you can seethe tiny, tiny opening each senor has). The lights on each sensor tell us how good of a connection we have, red means bad, yellow means we’re getting close, and green means good. 

Today’s post was inspired by a conversation I was having yesterday in the comment section (you know who you are and thank you for the questions). I thought I would elaborate on how we record from the brain and why. There are a lot of different ways we can do this, some of them are super invasive and others are non-invasive. In the lab I work in now, we do things non-invasively there are good things about this and bad things about this, so let’s get into it!

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Day #132: Rat model validation!

stock photography Pet rat closeup

Yesterday I mentioned that I had some rat data to go through. It was an old(er) dataset, about five years-old to be exact, but it was one that was going to help me validate some of my findings. Unfortunately there existed no invasive human datasets to compare my human data to, so I needed to find an animal model, in this case a rat model. Let’s discuss the importance.

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Day #110: Experiment!

EEG setup

This is an actual photo from my experiment setup, one of my colleagues is adding gel to the sensors. While the giant syringe looks scary, it isn’t. It’s full of conductive gel that gets placed between the head and the sensor. There is no pain or puncturing of the skin involved. Afterwards the gel washes out of the hair. The real pain is sitting for ~30 minutes or so while we gel each electrode enough to get a good reading.

A few days ago I mentioned I did a thing, well an experimental thing really. It was… fun? It was definitely something. Overall it went well, but I said I would give everyone an update and I try to be a man of my word, so let’s do this.

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Day #106: Super Busy!!!!!

Today I had my experiment (yay), so now I need to process the data. I also sat in another PhD defense for one of our lab members, so now that I have a free second I wanted to give an update. Expect a longer post tomorrow, but for today, I have sooooo much work to do!

Until next time, don’t stop learning!


Day #105: Defense day #1

phd defense

This basically sums up today’s post…

Here we are another day another post. Today I will be spending the bulk of my time studying and getting my slides ready for the confrence I’ll be attending next week. That will be … fun? However today is also an important day for one of my fellow students, he’s defending his PhD.

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Day #104: Experiment Prep

EEG headset

It looks like things are moving a little quicker than I thought for me. As you may or may not know, I’m getting ready to do an experiment. Well, we finally (finally!) finalized the protocol and just in time too. While I won’t make the deadline for my project update, I will have some data to show when we get to the conference, which is a good consolation prize.

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Day #88: Experimental Headaches

EEG

EEG cap

I’ve talked about my impending deadlines a lot lately. I also mentioned that I had an experiment that I needed to do to meet a deadline, well it looks like we may or may not meet this goal. Let’s talk about the latest headaches.

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Day #20 : Independent Events – 365 DoA

correlation

By: xkcd

 

Because we introduced the central limit theorem last post, it’s time to introduce another important concept. The idea of independent events, while this may seem intuitive, it is one of the assumptions we make in parametric statistics, another concept we will define, but for now let’s jump into independence.*

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Day #19 : The Central Limit theorem – 365 DoA

 

 

CLT

Well here we are again, if you recall from our last post, we talked Bonferroni Correction. You may also recall that when the post concluded, there was no real topic for today. Well after some ruminating, before we jump into more statistics, we should talk about the central limit theorem. So let’s do a quick dive into what that is and why you should know it!*

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Day #18 : The Bonferroni Correction – 365 DoA

Keep calm and do the Bonferroni corrrection

Keep calm and do the Bonferroni corrrection

By now we are masters of statistics… right? Okay, not really, but we are getting there. So far we’ve covered two types of errors, type 1 which you can read about here, and type 2 which you can read about here. Armed with this new knowledge we can break into a way to correct for type 1 errors that come about from multiple comparisons. Sound confusing? Well, not for long, let’s break it down and talk Bonferroni.*

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Day #17 : Type 2 errors – 365 DoA

 

cat asleep

Last post we did a quick bit on type 1 errors. As with anything, there is more than one way to make an error. Today we are talking type 2 errors! They are related in the sense and we’ll go over what that means and compare the two right… now!*

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Day #16 : Type 1 errors – 365 DoA

tiny dog yawning

tiny dog yawning

We did it, we cracked the coin conundrum! We managed the money mystery! We checked the change charade! We … well you get the idea. Last post we (finally) determined if our coin was bias or not. Don’t worry, I won’t spoil it for you if you haven’t read it yet. I actually enjoyed working through a completely made up problem, so if you haven’t read it, you really should. Today we’re going to talk dogs, you’ll see what I mean, so let’s dive in.*

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Day #15 : Significance, Part 3 – 365 DoA

Standard_deviation

Where does our observation fall on the probability density function?

It looks like we’ve arrived at part 3 of what is now officially a trilogy of posts on statistical significance. There is so much more to say I don’t want to quite call this the conclusion. Instead, let’s give a quick review of where we left off and we can get back to determining if an observed value is significant.*

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Day #14 : Significance, Part 2 – 365 DoA

Bar graph showing z score across trials
Bar graph showing z score across trials

Z-score bar graph that I made just for all of you using some data I had laying around. If you’re new to statistics it may not make sense, but rest assured we will make sense of it all!

Well here we are two weeks into 365DoA, I was excited until I realized that puts us at 3.8356% of the way done. So if you remember from last post we’ve started our significance talk, as in what does it mean to have a value that is significant, what does that mean exactly, and how to do we find out? Today is the day I finally break, we’re going to have to do some math. Despite my best efforts I don’t think we can finish the significance discussion without it and still manage to make sense. With that, let’s just dive in.*

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Day #13 : Significance, Part 1 – 365 DoA

Normally distributed data shown using a histogram plot
Normally distributed data shown using a histogram plot

Histogram of normally distributed data. It looks very… nomal. No it really is normally distributed, read on to find out what that means and how we can use it.

If you’ve read my last post I hinted that today we would discuss filtering. Instead I think I want to take this a different direction. That isn’t to say we won’t go over filtering, we most definitely will. Today I want to cover something else though, significance. So you’ve recorded your signal, took an ensemble average, and now how do we tell if it actually means something, or if you are looking at an artificial or arbitrary separation in your data (IE two separate conditions lead to no difference in your data). Let’s look at significance.*

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Day #12 : Signal, cutting through the noise – 365 DoA

example data

45 separate trials of very noisy data with the average of those trials (black). Believe it or not, this is actually very useful and very real data from something I am currently working on.

Noise, it can be troublesome. Whether you are studying and someone is being loud or you are trying to record something, noise is everywhere <stern look at people who talk during movies>. Interestingly enough the concept of noise in a signal recording sense isn’t all too different from dealing with talkative movie goers, so let’s talk noise!*

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