Case Studies

At Gowerlabs we pride ourselves on our friendly and expert customer service. Researchers working with the NTS Optical Imaging System have direct communication with our physicists and engineers, helping to bring ambitious projects to fruition. Here we feature a selection of our customers’ work, demonstrating the versatility and capability of the NTS Optical Imaging System.

 

In upper limb tetraplegia reconstructive surgery, a functionally intact muscle is detached, rerouted and reattached to a nonworking muscle to replace its original function. This gives patients the ability to grip objects again; restoring this aspect of hand function can hugely increase quality of life. At the Centre for Advanced Reconstruction of Extremities (CARE) at Sahlgrenska University Hospital (Gothenburg, Sweden), researchers are using the NTS Optical Imaging System and fMRI to map patterns of brain activity after reconstructive upper limb surgery in individuals with tetraplegia. By recording the haemodynamic response to tasks such as key-pinching and elbow flexing, CARE is studying the resultant cortical plasticity in the brain as movement is restored.

The video below shows upper limb tetraplegia reconstructive surgery taking place at CARE (content warning - graphic images of surgery):

After extensive discussions between Gowerlabs and CARE, a DOT array was designed that could image the primary motor cortex/primary somatosensory cortex (M1/S1), supplementary motor area (SMA), and premotor cortex (PMC). The array consists of 16 dual-wavelength sources and 16 detectors, including two short separation channels to remove scalp contamination in the signal.

During the experiment, both the control group and the patient group were asked to use their right hand to perform isometric key pinch and elbow flexor tasks. Each task was repeated five times, interspersed by periods of rest. The data from the NTS Optical Imaging System were analysed and reconstructed into images with the help of researchers at UCL.

Preliminary DOT results suggest that the control group demonstrates a clear lateralisation of the movement tasks to the contralateral hemisphere. In contrast, for the tetraplegic group the haemodynamic response to both tasks was highly bilateral. The findings suggest that upper limb tetraplegia reconstructive surgery induces cortical plasticity of the M1/S1 region to restore thumb function and enable gripping.

For more information about CARE and their research, please contact Dr. Lina Bunketorp Käll (lina.bunketorp@neuro.gu.se).

 
 
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Founded in 2013, neoLAB is a collaborative research partnership between UCL and Cambridge University. Based in the Evelyn Perinatal Imaging Centre (EPIC) at the Rosie Hospital, Cambridge, the group is comprised of physicists, computer scientists, and engineers from UCL (who develop the imaging systems) collaborating with clinicians and researchers from Cambridge. Located directly below the Neonatal Intensive Care Unit (NICU) at the Rosie Hospital, the EPIC was purpose-built to provide researchers unparalleled access to multiple different imaging devices for investigating neonatal brain function, including electroencephalography (EEG), fNIRS, and magnetic resonance imaging (MRI). This makes it one of the best locations in the world to study baby brain development.

The NTS Optical Imaging System is used by doctors and other researchers to investigate brain function in both healthy and sick infants. Because of the portability of the system, it can be wheeled right up to the cot of a baby in the NICU with ease. This way the patient is not disturbed and his or her clinical care can continue without interruption.

NeoLAB researchers have used the system to successfully scan the brain activity of sick infants when they are experiencing seizures and/or seizure-like events (such as burst suppression). This was made possible by integrating optical imaging with EEG. The following video shows the hemodynamic response to multiple seizures in an infant brain over the course of 5 minutes (DOT images are on top, EEG signals on bottom). Globally the brain primarily shows a short increase in total haemoglobin concentration before experiencing a profound and long-lasting decrease. This corresponds to a significant reduction in blood volume where the brain is below normal oxygen levels for several minutes:

Not all infants with brain damage display such obvious seizures on EEG. Others may exhibit only subtle changes in their EEG (such as burst-suppression) which can be difficult to detect, but this information can be complemented with DOT imaging. Several infants experiencing burst-suppression events were imaged by neoLAB, and upon compiling the data it was clear that there were dramatic swings in total blood volume within the brain in response to these brief periods of abnormal activity:

More details about neoLAB’s work imaging seizures in the infant brain can be found in the following publications:

  • M. Chalia, C. Lee, L.A. Dempsey, A.D. Edwards, H. Singh, A.W. Michell, N.L. Everdell, R.W. Hill, J.C. Hebden, T. Austin, R.J. Cooper. “Hemodynamic response to burst-suppressed and discontinuous electroencephalography activity in infants with hypoxic ischemic encephalopathy.” Neurophotonics 3(3), 031408, 2016.
  • H. Singh, R.J. Cooper, C. Lee, L.A. Dempsey, A. Edwards, S. Brigadoi, D. Airantzis, N.Everdell, A. Michell, D. Holder, J.C. Hebden, T. Austin. “Mapping cortical haemodynamics during neonatal seizures using diffuse optical tomography: A case study.” NeuroImage: Clinical 5, 2014.
  • R.J.Cooper, J.C.Hebden, H.O’Reilly, S.Mitra, A.Michell, N.L.Everdell, A.P.Gibson, T. Austin. “Transient haemodynamic events in neurologically compromised infants: A simultaneous EEG and diffuse optical imaging study.” Neuroimage 55:1610-6, 2011.

For more information about neoLAB’s research and the facilities at the EPIC, please visit their website.

 
 

At UCL, the Division of Psychiatry and Department of Medical Physics and Biomedical Engineering are collaborating to study functional changes in the brains of people with Down Syndrome (DS) as they age. Whilst the life expectancy of those with DS has risen dramatically over the past 50 years, it is now apparent that they suffer disproportionately from Alzheimer’s disease (AD). To address the lack of functional neuroimaging research in the DS population, UCL is using fNIRS and DOT to study Executive Function (EF) in people with DS of all ages. Decline in EF is possibly an early feature of AD in DS and the research team hopes to monitor EF abilities in adults with DS to better understand the corresponding haemodynamics in the brain.

The Frontal Cortex (FC) is highly involved in EF, showing activation during tasks requiring rule learning, shifting and inhibition. With the help of Gowerlabs, the UCL researchers developed a DOT array covering the FC and superior temporal cortex with 16 sources and 16 detectors, for a total of 44 channels. Data was acquired with the NTS Optical Imaging System during several different paradigms meant to activate the FC, including a Go/No-go task, picture Stroop task, verbal fluency task and dimensional change card sort task. To date, pilot studies with 9 adults with DS and 12 control participants have been completed and a larger DS study is now underway.

This is, to our knowledge, the first study to use fNIRS with adults with DS. Crucially, this research is possible because fNIRS allows more natural movement than other imaging modalities such as MRI. The DS individuals tolerated the headgear and Gowerlabs fibre optics well, making it possible to study EF in this population. Gowerlabs is excited to see where this new study leads and will continue to provide consultation on the research as it progresses.

Formore information please see the website of the LonDownS Consortium or contact Rosalyn Hithersay at r.hithersay@ucl.ac.uk .

 
 

Researchers at the UCL Institute of Cognitive Neuroscience and Babylab (Birkbeck College, London) are collaborating to study the impact of early speech and language experience on the neural representation of language in infancy. Led by PI Dr. Evelyne Mercure, the group is interested in comparing hearing infants of Deaf mothers who use a sign language as their dominant language (HoD infants) with hearing infants of hearing mothers (HoH infants). This is because despite having normal hearing, HoD infants have a different early experience of speech and language to that of HoH infants. First, since Deaf mothers are more likely to use signing than auditory speech, their infants are likely to have reduced exposure to auditory spoken language. Second, the experience of HoD infants includes both a visual language (e.g. British Sign Language (BSL)) and an auditory language (e.g. English). The team decided to compare HoD infants to bilingual HoH individuals since this latter group is also exposed to two languages (both auditory). They also included a control group comprised of monolingual HoH infants. They hypothesised that the experience of HoD infants will influence their neural representation of language.

All subjects had fNIRS data acquired using the Gowerlabs NTS Optical Imaging System. Headgear containing 38 source-detector channels was developed at Babylab and designed to image the temporal and temporoparietal areas of the brain. The latter area was included because this part of the brain has previously been seen to play an important role in processing sign language. There were 38 channels in the array with 2 cm source-detector separations. Lead PI of the project, Dr. Evelyne Mercure, commented that she is very happy with fNIRS as a tool to scan baby brain function in comparison to her previous experiences with EEG and fMRI. She can scan the infants when they are awake and behaving naturally, plus her success rate is higher since the subjects tolerate the headgear well.

Each of the three subject groups were shown videos of people telling short stories in four different languages, and their functional responses are then compared. The languages were: English (familiar spoken language), French (unfamiliar spoken language), British Sign Language (familiar sign language to HoD infants) and French Sign Language (unfamiliar sign language). The aim was to assess how the brain represents spoken and signed languages, as well as familiar and unfamiliar languages. To date the team have scanned around 100 infants with the NTS Optical Imaging System for this study!

Preliminary results from the temporal channels suggest that spoken language causes a strong activation in the temporal cortex across all subjects. For the HoH monolinguals the response is highly bilateral, but in the HoD infants it is more restricted and left-lateralised; whilst in the HoH bilinguals it is more right-lateralised. The rich data-set collected by this group is still being analysed, and we can expect many more interesting results from this study in the near future.

For more information, please find Dr. Evelyne Mercure’s contact details on the UCL Institute of Cognitive Neuroscience website.