Greetings! I am having trouble with the infant caps. We purchased Infa 1 and Infan 1/2 for use with 6-month-olds. Based solely on head circumference measurements we are mostly using Infa 1/2 but we've found this cap to be too big (even though the infants are fitting into the range). We're getting readings but we also tend to see some noise in the signal and the cap is creeping up in the front. We tie the chin strap tight (...we even need to put a piece of gauze under the strap b/c it makes the babies' chin red) and we also tie the drawstring located on the side. This cap just doesn't seem to fit the way it should fit. I originally thought that maybe we started with a few odd-shaped head babies but we ran approximately 25 infants and the cap fit perfectly for about 2 infants. We have an experienced EEG experimenter fitting the cap so we are following the correct procedure. Additionally, the cap was used only ~30 times or so making it relatively new (i.e., not stretched out).
Any suggestions on what might help? If you look at pictures of the child wearing the cap on Cortech Solution's website, even the cap on that infant appears to run high in the front. Any helpful suggestions would be most appreciated.
Thank you!
~jennifer
Caps for Infants Not Fitting According to Head Circumference
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infantresearcher
- Posts: 2
- Joined: Wed Aug 08, 2012 10:59 pm
Re: Caps for Infants Not Fitting According to Head Circumfer
Infant head circumferences vary quite a lot, even when the infants are of the same age. What is the median head circumference of your 6 month olds? I know of a lab that tried the Infa3 caps on 6 months olds, but they said those were to small. So it looks like Infa2 (38-42 cm) should be the right size for you.
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infantresearcher
- Posts: 2
- Joined: Wed Aug 08, 2012 10:59 pm
Re: Caps for Infants Not Fitting According to Head Circumfer
Hi Robbie,
Thank you so much for your reply. The median head circumference is 43.25cm for our 6-month-sample. Before we purchased the Infa 1 and Infa 1/2 caps we recorded head circumference measures from another group of 6-month-olds who were participating in one of our studies. The median of that group was 43.5cm. That's why we purchased the Infa 1/2 (40-44cm) and Infa1 (42-46cm) caps. We recently purchased the Infa2 cap (38-42cm) because we suspected the Infa 1/2 cap was too big for the majority of our babies. As we await delivery, we are currently borrowing another labs Infa2 cap to see if that helps. Just looking at our data, all of our babies should have fit into either the Infa 1 or Infa 1/2 cap (range 40.5-46cm) so I'm very confused by the measurements for these caps.
Adding to this, we are having a very difficult time keeping the cap low in the front so I'm wondering if we are trying to pull it down too far? I looked at a few pictures of infants who were wearing the caps on our vendor (Cortech Solutions) website and on one of the pictures the infant has the cap down to where I think it should be (i.e., approximately slightly above the eyebrows), but in another picture the cap is really high on the infant's forehead. This is usually where the cap ends up for us at the end of the study. Do we need to buy the harness to keep it in place? In another forum post from your site, someone was talking about the distance between certain electrodes when the cap is placed on the head (I think between T7 and T8). Do you have any similar parameters for infants so that we can make sure we're using the right-sized cap? Just so we're on the same page, our research assistant is very much familiar with applying EEG caps on young children in addition to being familiar with the detailed cap-fitting instructions provided in the ActiveTwo Operating Guide Manual.
Thank you so much for your reply. The median head circumference is 43.25cm for our 6-month-sample. Before we purchased the Infa 1 and Infa 1/2 caps we recorded head circumference measures from another group of 6-month-olds who were participating in one of our studies. The median of that group was 43.5cm. That's why we purchased the Infa 1/2 (40-44cm) and Infa1 (42-46cm) caps. We recently purchased the Infa2 cap (38-42cm) because we suspected the Infa 1/2 cap was too big for the majority of our babies. As we await delivery, we are currently borrowing another labs Infa2 cap to see if that helps. Just looking at our data, all of our babies should have fit into either the Infa 1 or Infa 1/2 cap (range 40.5-46cm) so I'm very confused by the measurements for these caps.
Adding to this, we are having a very difficult time keeping the cap low in the front so I'm wondering if we are trying to pull it down too far? I looked at a few pictures of infants who were wearing the caps on our vendor (Cortech Solutions) website and on one of the pictures the infant has the cap down to where I think it should be (i.e., approximately slightly above the eyebrows), but in another picture the cap is really high on the infant's forehead. This is usually where the cap ends up for us at the end of the study. Do we need to buy the harness to keep it in place? In another forum post from your site, someone was talking about the distance between certain electrodes when the cap is placed on the head (I think between T7 and T8). Do you have any similar parameters for infants so that we can make sure we're using the right-sized cap? Just so we're on the same page, our research assistant is very much familiar with applying EEG caps on young children in addition to being familiar with the detailed cap-fitting instructions provided in the ActiveTwo Operating Guide Manual.
Re: Caps for Infants Not Fitting According to Head Circumfer
Hi Jennifer,
The picture on the Cortechsolutions website shows a child of about 3? years old with a Small headcap: http://www.cortechsolutions.com/Product ... -caps.aspx
The picture shows a 64 channel headcap. The distance between FPz and AFz should be the same as the distance between FPZ and Nasion. In other words, FPz should be right in the middle of AFz and Nasion. Looking at the caps, I would say the photographer placed the cap a bit to high. The front of the cap should have been pulled more downwards, to the neighborhood of the eyebrows. Most people find it less comfortable when the front of the cap is pulled more downwards, also infants find this often irritating. Nevertheless in order for ones positions to map out correctly, you must always try to position the 4 reference points as good as possible (Inion, Nasion Pre-Auricular points)
Keep me posted on the fit of the Infa 2 cap.
A nice thing about active headcaps is that these active electrodes make good signal contact with the skin so easily, that the electrodes do not need to be pressed as firmly to the skin as we were used with passive headcaps. So, active headcaps don't need to be as tight as passive headcaps. As long as the electrodes are not totally floating, you'll still have a clean signal
I totally agree with kids not liking the rim of the headcap so close to their eyebrows. You might try the harness, some people like it, others don't. Most common reason why people use the harness is that it supposedly better prevents (as compared to when using the standard straps) the headcap from shifting when turning the head. Body harnesses come in 3 sizes: S, M and L.
This picture on the Biosemi website shows a 64 channel layout:
http://www.biosemi.com/pics/cap_64_layout_medium.jpg
Basically, when positioning the caps, you start with checking that the distance between Nasion-FPz and FPz-AFz is the same. Then you check that Iz is positioned right on top of Inion. If the last is not the case, you'll have to take another size headcap so it will. Finally, you manouver the cap so that the distance between the LeftPreAuricularPoint-T7 and the RightPreAuricularPoint-T8 is the same.
The picture on the Cortechsolutions website shows a child of about 3? years old with a Small headcap: http://www.cortechsolutions.com/Product ... -caps.aspx
The picture shows a 64 channel headcap. The distance between FPz and AFz should be the same as the distance between FPZ and Nasion. In other words, FPz should be right in the middle of AFz and Nasion. Looking at the caps, I would say the photographer placed the cap a bit to high. The front of the cap should have been pulled more downwards, to the neighborhood of the eyebrows. Most people find it less comfortable when the front of the cap is pulled more downwards, also infants find this often irritating. Nevertheless in order for ones positions to map out correctly, you must always try to position the 4 reference points as good as possible (Inion, Nasion Pre-Auricular points)
Keep me posted on the fit of the Infa 2 cap.
A nice thing about active headcaps is that these active electrodes make good signal contact with the skin so easily, that the electrodes do not need to be pressed as firmly to the skin as we were used with passive headcaps. So, active headcaps don't need to be as tight as passive headcaps. As long as the electrodes are not totally floating, you'll still have a clean signal
I totally agree with kids not liking the rim of the headcap so close to their eyebrows. You might try the harness, some people like it, others don't. Most common reason why people use the harness is that it supposedly better prevents (as compared to when using the standard straps) the headcap from shifting when turning the head. Body harnesses come in 3 sizes: S, M and L.
This picture on the Biosemi website shows a 64 channel layout:
http://www.biosemi.com/pics/cap_64_layout_medium.jpg
Basically, when positioning the caps, you start with checking that the distance between Nasion-FPz and FPz-AFz is the same. Then you check that Iz is positioned right on top of Inion. If the last is not the case, you'll have to take another size headcap so it will. Finally, you manouver the cap so that the distance between the LeftPreAuricularPoint-T7 and the RightPreAuricularPoint-T8 is the same.