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Posts tagged “neurology

Day 296: Review – Spinal Rhythm Generation by Step-Induced Feedback and Transcutaneous Posterior Root Stimulation in Complete Spinal Cord–Injured Individuals

Black and white diagram showing the front and back of a human with the the placement of electrodes over the lower abdominal area and separate electrodes over T11-T12 of the spinal cord a third image to the right shows the side of the spinal column with spinal cord to depict the location of the back electrodes with relation to the spinal cord
Black and white diagram showing the front and back of a human with the the placement of electrodes over the lower abdominal area and  separate electrodes over T11-T12 of the spinal cord a third image to the right shows the side of the spinal column with spinal cord to depict the location of the back electrodes with relation to the spinal cord

Transcutaneous posterior root stimulation: Paravertebral and abdominal skin electrode placement (this is just a portion of figure 1 of this paper.

Normally I’m somewhat excited to post these, but with everything going on you’ll have to pardon my lack of joy. However, it’s been two weeks so I need to review another paper so I’m sharing it here as well as sending my PI a copy. The study is a few years old, but it’s open access so you can read it if you’re interested. Transcutaneous spinal cord stimulation (TSS) is one part of my research in case you couldn’t tell from all the spinal cord and TSS studies and posts. I find it interesting and it gives me hope that we can help a whole lot of people living with spinal cord injury. Anyway give it a read and get out there and protest for a better world.

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Day 282: Review – Transcutaneous spinal cord stimulation of the cervical cord modulates lumbar networks

Experimental Setup and tSCS electrode placement (A) H-reflexes were evoked via stimulation of the tibial nerve and recorded in the soleus muscle during a consistent background contraction of ≈5% peak muscle activity. The left leg was held static in an extended position, and stimulation to evoke the H-reflex was delivered with the left arm at 0°. (B) tSCS was delivered via two 2.5 cm round cathodic electrodes placed midline at C3-4 and C6-7 (cervical) or T11 and L1 (lumbar) spinous processes. Two 5 × 10 cm rectangular anodic electrodes were placed bilaterally over the iliac crests.
Experimental Setup and tSCS electrode placement (A) H-reflexes were evoked via stimulation of the tibial nerve and recorded in the soleus muscle during a consistent background contraction of ≈5% peak muscle activity. The left leg was held static in an extended position, and stimulation to evoke the H-reflex was delivered with the left arm at 0°. (B) tSCS was delivered via two 2.5 cm round cathodic electrodes placed midline at C3-4 and C6-7 (cervical) or T11 and L1 (lumbar) spinous processes. Two 5 × 10 cm rectangular anodic electrodes were placed bilaterally over the iliac crests.

Experimental Setup and tSCS electrode placement (A) H-reflexes were evoked via stimulation of the tibial nerve and recorded in the soleus muscle during a consistent background contraction of ≈5% peak muscle activity. The left leg was held static in an extended position, and stimulation to evoke the H-reflex was delivered with the left arm at 0°. (B) tSCS was delivered via two 2.5 cm round cathodic electrodes placed midline at C3-4 and C6-7 (cervical) or T11 and L1 (lumbar) spinous processes. Two 5 × 10 cm rectangular anodic electrodes were placed bilaterally over the iliac crests.

It’s that time again! My biweekly critical review paper is due for my PI. He gets a copy and so do all of you. This is a particularly interesting study that falls in line with a lot of research that I am doing, so it’s interesting to see how other groups are progressing. Overall I think this is a great study and while it is behind a paywall, I think I summed it up very well. The drawing they did (above) is awesome, especially for a scientific journal where we normally use simple line figures. Anyway, let’s get to it.

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Day 268: Review – Magnetospinography visualizes electrophysiological activity in the cervical spinal cord

Reconstructed currents of MSG from the cervical spondylotic myelopathy subject. There are two different sets of plots, the furthest left shows the electrophysiological recording taken from the epidural space and the other set shows the reconstructed currents using MSG. They agree fairly well.
Reconstructed currents of MSG from the cervical spondylotic myelopathy subject. There are two different sets of plots, the furthest left shows the electrophysiological recording taken from the epidural space and the other set shows the reconstructed currents using MSG. They agree fairly well.

This is the results of the cervical spondylotic myelopathy subject. The left graphs are the ascending spinal cord evoked potentials (this was electrophysiological recordings taken from the epidural space) by stimulation of the lower thoracic cord showing conduction block at the C4/5 disc level. The right graphs are the reconstructed currents at the midline of the cervical spinal canal (red) and 2 cm lateral (blue). The leading component (the first waveform in red) attenuated and disappeared through C4–6, and the trailing component (the second waveform in red) disappeared at C5/6. The perpendicular inflow components greatly attenuated at C4/5 (the second waveform in blue).

Another two weeks, another critical review. This time I was more critical than review, unlike the last one where I was blown away at the possibilities. Why was I more critical with this one? Well in my opinion, the authors took a baby step when they should’ve taken a leap. All that aside, it is an interesting study and one I hope has several follow up experiments. This one is open access as well, so have a read for yourself if you’re interested.

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Day 257: Tomorrow…

Sisyphus

Well we’re up against the wire now. Tomorrow is the due date for my paper and with it the video I am working on. Will I make it? How much work is left to do? Why am I talking in questions? Find out more… now…?

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Day 256: Two days left…

cookie monster

A live shot of me waiting for my data to finish processing

Well here we are and it’s… ♫ the finalllll count dowwwwwn!! ♫ My paper is due sunday at midnight and between the video I need to make, the data that still needs to be processed, and a shitty team mate who has done absolutely nothing to help, well I’ve got my work cut out for me.

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Day 255: The impossibility of complete knowledge

Magic-spells

Have you ever tried to learn something and you just can’t seem to get it to stick in your brain? That would be my life, well most of my adult life since I left the Marines. There is just so much knowledge in the world and wrapping my brain around even a fraction of a fraction of a fraction of that knowledge seems to be an impossible task. So what is one to do?

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Day 254: Review – A Brain to Spine Interface for Transferring Artificial Sensory Information

Fig.1 of paper showing drawing of implanted electrodes and the two experimental setups for the rat.
Fig.1 of paper showing drawing of implanted electrodes and the two experimental setups for the rat.

Experimental setup for artificial sensory discrimination using DCS and brain-to-spine interface. (a) Rats were implanted with recording electrodes in motor cortex (M1), somatosensory cortex (S1) and striatum (STR) and dorsal column stimulating electrodes in the thoracic epidural space.  (b) Behavioral setup for artificial sensory discrimination using DCS (c) Setup for the brain-to-spine interface consisted of two modified aperture width tactile discrimination boxes.

If you ever were to read one of my review papers, this one’s for you. It’s so awesome and falls in line fairly closely to the things I want to accomplish, albeit going a different route to get there. I’m super excited to share this with all of you and I hope I did the study justice in my summation and while I admit, I had far too much enthusiasm with this one, it shouldn’t take away from just how amazing this is, see for yourself! The study is open access too, so if you want to know more details, you can go take a look!

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Day 253: A race to the finish

finish line

Well still quite a bit of work to do and some of it was frustrating, but here we are. So let’s run through what I’ve got left to do before the end of the term (ALREADY?!) and talk about the next few posts since I have somewhat of a plan… for once.

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Day 252: Dead…line

dead...line

Today is the day, my group presentation is due. Is it done? Well… sort of? Okay not quite, but we’re getting there. My group member still sucks, but since I yelled at him (in a professional manner of course), he’s gotten a little better and has been more responsive, so what’s the hold up? What a great question, let me explain.

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Day 251: Deadline tomorrow

deadline

Well the apocalypse can’t stop the gears of education. Tomorrow is our final presentation for the class I am in, so there is work to be done and expectation maximization will come another day. For now let’s give a quick rundown of what I’m working on.

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Day 250: Maximum Likelihood Estimation

probability

If we are going to talk about expectation maximization (now that I’m done complaining for a bit), we are going to have to introduce the idea of maximum likelihood. It’s going to be very easy to introduce, but it is a very powerful tool in estimating the state of something. Of course, it takes understanding a little bit of statistics, but trust me, if I can understand it, so can you.

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Day 249: A stern email later…

angry

Photo of me responding to his email …

I don’t want to jinx it, I really don’t, but I have an update on my group member situation and it isn’t completely awful! I mean, I’m still doing all the work and blah, blah, blah, but I’ve got an interesting story and I hope that things will be better now.

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Day 248: A Virtual Conference

background

Every zoom meeting I try to break my PI and get him to laugh, this was my last attempt, still nothing… my work continues.

This will be my first conference since the pandemic and it will be a virtual one. To be completely honest, it wasn’t until yesterday that I was reminded we had one today. It’s a little bit different from our normal routine and I think that is what is throwing me off.
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Day 247: The Kalman filter – Part 2

Kalman filter estimate

The Kalman filter converges on the optimal state estimate using noisy measurements and a model that we create.

Okay I lied, I think we can do a better job explaining the Kalman filter, more importantly I have a fun little demo I can share with everyone. It’s not mine, but I like it a lot and it will give you a feel for what the kalman filter does. So let’s get started!
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Day 246: The Kalman filter

We have 3-dimensions here even though it is a 2 dimensional problem. the third dimension is time, this way we can see the path over the course of the recorded time. Notice there are no units, becuase in this case we were working with synthetic data so the units were meaningless and I did not include them.
We have 3-dimensions here even though it is a 2 dimensional problem. the third dimension is time, this way we can see the path over the course of the recorded time. Notice there are no units, becuase in this case we were working with synthetic data so the units were meaningless and I did not include them.

This is just one application for the Kalman filter, I estimated a two dimensional position using a random walk model. We have 3-dimensions here even though it is a 2 dimensional problem, the third dimension is time. This way we can see the path over the course of the recorded time. Notice there are no units, becuase in this case we were working with synthetic data so the units were meaningless and I did not include them.

Since we’ve been talking a lot about it, I thought it might be a good idea to formally introduce the Kalman filter. This will be a semi-high level introduction (like my knowing your spinal cord series), but at the end of it you should have a relatively good feel for what a Kalman filter is.
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Day 245: Fine, I’ll do it myself.

Thanos - I'll do it myself

I will not fail this class becuase of a shitty team member. I will not allow it, I’ve put too much effort and time into this class to do poorly at the last minute because my team member can’t be bothered to do the job he agreed to do. I suppose, this was… inevitable

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Day 244: The end of the term!?

end of term

Okay, where the hell did that come from?! It’s almost the end of the school term. WHAT THE HELL!? It feels like we just got started, but my instructor just sent out the final assignment, which is due the last week of school… next week. I’m sort of freaking out right now.

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Day 243: Deadlines approaching!

deadlines

It seems like it’s been non-stop for me left and right. I have experiments to do, papers to write, and classes to work on. With the pandemic I was hoping to get a chance to take a break, but nope it seems like I’m even busier than normal. I HAD thought that I was caught up finally when I finished processing some of the experimental data I had laying around, but nope I was reminded yesterday that I had not one, but two major deadlines coming.

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Day 242: Experimenting in the time of a pandemic

Experiment-blur

Another day forward in our new normal. I’ve left the house exactly once in the last two weeks and while it’s nice not having to commute to school, I do miss living in a world without the constant fear of catching the virus. What day is it? Who knows, it doesn’t matter anymore. I do have some things coming up though, so let’s talk about experimenting in the age of COVID-19.

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Day 239: Review – Burst-modulated waveforms optimize electrical stimuli for charge efficiency and fiber selectivity

Example processed nerve responses during stimulation trials.
Example processed nerve responses during stimulation trials.

Example processed nerve responses during stimulation trials. The individual CNAP responses for each stimulus (thin traces) were averaged (thick trace, n=20 stimuli). All traces are shown from time 0 to 6ms. The top trace corresponds to an amplitude of 0, the bottom 1mA, and the traces in between are arranged in increments of 0.2mA. Peak latencies and heights (o’s) and widths at half peak height (x’s) were extracted from the averaged signal. The peaks labeled for the 0mA trial are due to noise and baseline activity. These peaks are not actual response peaks from the nerve and are ignored.

Another two weeks, another critical review and as always since my PI gets a copy, so do you. Technically this should’ve come yesterday, but I really wanted to follow up with the Roosevelt mess going on. In any case today we are looking at something not quite spinal cord stimulation, but has applications in the spinal cord stimulation field. Let’s take a look!

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Day 225: Class presentations

Presentation

Presentation

For the past week we have been utilizing online resources so that classes can continue while we are all social distancing. While this is means that we mostly use Zoom, we also have message boards and other resources that we can use. However, these resources are sometimes a poor substitute for in person classes. This is especially apparent when we have certain assignments for the class, such as a group presentation.

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Day 224: Review – Cortical and Subcortical Effects of Transcutaneous Spinal Cord Stimulation

Figure 1 of the paper showing the experimental set-up and the type of pulse used for stimulation
Figure 1 of the paper showing the experimental set-up and the type of pulse used for stimulation

Experimental set-up. (A) Participants were comfortably seated in a customized chair during transcutaneous electrical spinal stimulation (TESS) or sham-TESS for 20 min. TESS was delivered using a surface electrode on the back of the neck between C5–C6 spinous processes segments (cathode) and a surface electrode in each anterior crest of the hip bone (anode) using a custom made 5 channel stimulator (BioStim5, Cozyma). Electrophysiological and behavioral outcomes were tested before (Pre) and immediately after, 15, 30, 45, 60 and 75 min after the end of the stimulation or sham stimulation period. (B) Schematic representation of the type of current used during TESS. We used 5 biphasic pulses at 5kHz with each biphasic pulse lasting for 200us. The middle scheme shows the blocks of 5 biphasic pulses passed at a 30Hz frequency. Lower part of the schematic shows the number of pulses delivered in one second.

Well it’s been two weeks since the last critical review so it’s that time again. As usual, my PI gets a copy and so do all of you. Since I’ve done several of these now (this is number six) I have a category just for these reviews called critical reviews. This is a really new study which tries to help tease apart what we are actually stimulating when we apply transcutaneous spinal stimulation. I think it’s a super interesting paper and I hope you do as well.

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Day 214: Know your spinal cord – The Recap

motor neuron histology

It’s day fifty-four and we’ve hit the end of our journey for this mini-series. For one last time, you can find all our posts in the neuroanatomy category. Everything comes to an end eventually and today I think we should do a small wrap up. This isn’t just a repeat of everything we went over though, we’re going to attempt to tie a lot of the topics together. So let’s give this a shot.

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Day 213: Know your spinal cord – Translating neural signals

whole brain and spinal cord dissected

whole brain and spinal cord dissected

Here we are on day fifty-three, we are nearing the end for sure. I was going to end the series today, but there is at least one more thing that I think will be interesting to cover. As always, you can find all of our posts in the neuroanatomy category, after all there are quite a few now. Today we are going to talk about how the brain and muscles use different signals to communicate. Basically, they speak different languages; let’s talk about what that means.

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