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Sa-003-Visual cognition and dyadic interactions in caregivers and infants.
This study investigated whether there was an association between caregiver and infant visual cognition, and how caregiver-infant dyadic interactions were linked to this association. Visual cognition was measured using the preferential looking task. Caregivers and infants also engaged in unstructured play with toys. fNIRS was used to record brain activation. We found that there was an association between caregiver and infant visual cognition during experimental paradigms, and an association between caregiver and infant behaviors during dyadic interactions. Lastly, we find robust links between visual cognition and dyadic behaviors in caregivers and infants separately. Continue reading
Fr-008-fNIRS Evaluation of Cortical Reorganization Following Brief Speech-in-Noise Training
This study investigates cortical effects of single-session speech-in-noise (SIN) training using fNIRS and assesses data reproducibility. Thirty normal-hearing participants underwent SIN training with noise-vocoded stimuli. Significant post-training SIN enhancements were found, particularly in those with poorer initial performance or lower pre-training activation in the left middle temporal gyrus (MTG). MTG activation to trained stimuli decreased post-training, suggesting improved neural processing efficiency. Group-level reliability was confirmed, but individual-level reproducibility of fNIRS data was poor. These findings underscore the significance of fNIRS in elucidating the mechanisms driving auditory learning and plasticity yet highlight the challenges in translating fNIRS data to clinical practice. Continue reading
Vi-025-Imaging static absorbing properties using wavelength modulated near-infrared spectroscopy
A method called wavelength-modulated near-infrared spectroscopy is used to estimate the absolute concentrations of absorbers in highly scattering media using measurements of the rate of change of optical attenuation with wavelength. The method is demonstrated using three experimental systems based on a wavelength-modulated source, a spectrometer, and discrete sources at adjacent wavelengths. Measurements are independent of absolute intensity and thus less influenced by changes in coupling (to which hair is a significant contributor) which cause artefacts in conventional NIRS data. Images of a tissue equivalent phantom clearly reveal internal absorbers despite a random layer of dark hair on the surface. Continue reading
Fr-012-Somatotopic organization of the thumb and shoulder Nogier points in the primary somatosensory cortex using HD-fNIRS
This study investigated the somatotopic representation of thumb and shoulder Nogier points in the primary somatosensory cortex (S1) using high density functional near-infrared spectroscopy in 17 healthy adults. Tactile stimulation at these points revealed distinct lateral (thumb) and medial (shoulder) activations, with ipsilateral dominance for the thumb and contralateral for the shoulder. A positive correlation was found between reported stimulation pressure and brain activity. Mild pain and pressure sensations were reported, confirming the somatotopic organization of ear points in S1, which has implications for understanding sensory mapping and its clinical and therapeutic applications. Continue reading
Vi-017-Near infrared spectroscopy and its acquisition parameters in cochlear implant users: a systematic review
Abstract: This study aims to identify the acquisition parameters of functional near-infrared spectroscopy (fNIRS) in cochlear implant users. Methods: A systematic literature review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: Nineteen studies were included, 13 of which presented a low risk to bias. Conclusion: there were common acquisition parameters for fNIRS in cochlear implant users: predominant use of auditory stimuli in the form of words and phrases presented in a free field environment, bilateral recording of responses in the temporal lobe, incorporation of visual stimuli, study participants were alert and awake. Continue reading
Vi-016-Cortical responses to speech stimuli in a child using Cochlear Implant and Hearing Aids: case study
Abstract: This case report involves the characterization of cortical responses using Functional Near-Infrared Spectroscopy (fNIRS) with speech stimulation and the hearing and language performance of a child using a Cochlear Implant (CI) in the Left Ear and an Hearing aids (HA) in the Right Ear in auditory rehabilitation for five years. Methods: Clinical protocols were applied to characterize auditory-linguistic performance and fNIRS on the NIRXSport1 equipment with /ba/ and /da/ speech stimuli, with electronic devices connected, in a habituation and dishabituation paradigm. Results: the child showed physiological responses in the temporal cortex with no significant difference between the hemispheres. Continue reading
Fr-009-Orthostatic Hypotension in Parkinson’s Disease is Associated with Lower Neural Efficiency During Verbal Letter Fluency Testing While Upright: An fNIRS Study
In Parkinson’s disease (PD) orthostatic hypotension (OH) is associated with cognitive impairment. This study aimed to determine positional differences in cognitive performance and cerebral hemodynamics in PD with and without OH, since OH could be a treatable risk factor for cognitive dysfunction. Participants with PD with OH (n=4) and without OH (n=8) underwent repeated cognitive testing in supine/sitting and upright positions while wearing a functional near infrared spectroscopy (fNIRS) sensor. The group with OH had low neural efficiency during the verbal letter fluency test while upright, supporting the hypothesis that impaired cerebral hemodynamic regulation contributes to cognitive impairment. Continue reading
Vi-024-Continuous blood pressure monitoring using forehead NIRS-PPG (FlexNIRS) and deep learning
We explored the utility of forehead near-infrared spectroscopy photoplethysmography (NIRS-PPG) coupled with a deep learning model integrating convolutional and long short-term memory (CNN-LSTM) networks for arterial blood pressure prediction. The model was validated on two patients undergoing carotid endarterectomy, showing strong correlation between predicted and actual blood pressure values. We are validating the model across seven additional subjects. Preliminary results indicate that unsupervised deep learning applied to NIRS-PPG data offers promising potential for robust, accurate continuous blood pressure monitoring. Continue reading
Fr-026-Real-time inference of molecular composition from broadband spectroscopy of brain tissue
We analyze a technique for fast and accurate inference of changes in the molecular composition of brain tissue from broadband NIRS and HSI monitoring. The method is based on the Beer-Lambert law to analytically connect the spectra with concentrations and utilizes deep learning to speed up the concentration inference compared to traditional optimization means. The results reveal a sub-second molecular composition inference and a possibility of contrasting semantically different physiological parts. Continue reading
Vi-026-Changes in Cerebral Haemodynamic Responses During a Sustained Attention Task Following Exertional Hyperthermia
The effects of exertional hyperthermia on neural responses and sustained attention remains equivocal. We evaluated the continuous changes in cerebral haemodynamic responses in bilateral dorsolateral prefrontal cortices during a sustained attention task at the start and end of exercise under heat stress. Exertional hyperthermia under warm environmental conditions resulted in decreased cerebral blood volume and higher error rate compared with cool environmental conditions. Findings suggest potential associations between alterations in cerebral haemodynamic responses and impairments in sustained attention during exercise in the heat. Continue reading