Browsing by Author "Heiskala, Juha"
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- Accurate modelling of tissue properties in diffuse optical imaging of the human brain
Doctoral dissertation (article-based)(2009) Heiskala, JuhaDiffuse optical imaging (DOI) is an emerging imaging modality for non-invasive functional medical imaging, using near infrared (NIR) or visible red light. The innovation is to derive functional information about living tissue from measurements of light that has passed through it. Optical imaging can be applied to imaging of tissues as diverse as the central nervous system, female breast, muscle, and joints of fingers. This thesis addresses the application of DOI to studying the human brain. In this thesis, the problems of modelling light propagation in the adult and infant human head, and reconstructing three-dimensional images of functional changes in the brain using optical measurements, are addressed. Difference imaging, where changes from baseline optical parameters rather than absolute parameter values are reconstructed, is considered. The goal was to develop methods for accurate modelling of light propagation and to clarify how specific aspects of the computational modelling affect the reconstruction of functional images from optical measurements of the human brain. Specifically, the significance of anisotropic light propagation in the white matter, and a priori knowledge of the anatomy and the optical properties of the head and brain are studied. Moreover, a generic probabilistic atlas model of the infant head to enhance image reconstruction is developed. Significance of anisotropic light propagation was found to be small in optical imaging of the adult brain. Although anisotropic light propagation may have a larger impact on the measured signal when infants are imaged, results suggest that image reconstruction can be performed without taking anisotropy into consideration. The use of a priori anatomical knowledge was found to significantly improve the accuracy and robustness of image reconstruction in difference imaging. The results suggest that for optimal reconstructions, individual MR imaging based anatomical data should be used when possible. For cases where individual anatomical data is not available, atlas models should be developed. An important consideration is how to obtain the baseline optical parameters of tissue classes in the anatomical model. Literature-derived parameters can be used as a starting point. For optimal results however, methods should be developed for estimating the baseline parameters from measured data. - Affective and non-affective touch evoke differential brain responses in 2-month-old infants
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2018-04-01) Jönsson, Emma H.; Kotilahti, Kalle; Heiskala, Juha; Backlund Wasling, Helena; Olausson, Håkan; Croy, Ilona; Mustaniemi, Hanna; Hiltunen, Petri; Tuulari, Jetro J.; Scheinin, Noora M.; Karlsson, Linnea; Karlsson, Hasse; Nissilä, IlkkaCaressing touch is an effective way to communicate emotions and to create social bonds. It is also one of the key mediators of early parental bonding. The caresses are generally thought to represent a social form of touching and indeed, slow, gentle brushing is encoded in specialized peripheral nerve fibers, the C-tactile (CT) afferents. In adults, areas such as the posterior insula and superior temporal sulcus are activated by affective, slow stroking touch but not by fast stroking stimulation. However, whether these areas are activated in infants, after social tactile stimulation, is unknown. In this study, we compared the total hemoglobin responses measured with diffuse optical tomography (DOT) in the left hemisphere following slow and fast stroking touch stimulation in 16 2-month-old infants. We compared slow stroking (optimal CT afferent stimulation) to fast stroking (non-optimal CT stimulation). Activated regions were delineated using two methods: one based on contrast between the two conditions, and the other based on voxel-based statistical significance of the difference between the two conditions. The first method showed a single activation cluster in the temporal cortex with center of gravity in the middle temporal gyrus where the total hemoglobin increased after the slow stroking relative to the fast stroking (p = 0.04 uncorrected). The second method revealed a cluster in the insula with an increase in total hemoglobin in the insular cortex in response to slow stroking relative to fast stroking (p = 0.0005 uncorrected; p = 0.04 corrected for multiple comparisons). These activation clusters encompass areas that are involved in processing of affective, slow stroking touch in the adult brain. We conclude that the infant brain shows a pronounced and adult-like response to slow stroking touch compared to fast stroking touch in the insular cortex but the expected response in the primary somatosensory cortex was not found at this age. The results imply that emotionally valent touch is encoded in the brain in adult-like manner already soon after birth and this suggests a potential for involvement of touch in bonding with the caretaker. - Diffractive scattering at LHC
Helsinki University of Technology | Master's thesis(2001) Heiskala, Juha - Hemodynamic responses to emotional speech in two-month-old infants imaged using diffuse optical tomography
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-12-01) Shekhar, Shashank; Maria, Ambika; Kotilahti, Kalle; Huotilainen, Minna; Heiskala, Juha; Tuulari, Jetro J.; Hirvi, Pauliina; Karlsson, Linnea; Karlsson, Hasse; Nissilä, IlkkaEmotional speech is one of the principal forms of social communication in humans. In this study, we investigated neural processing of emotional speech (happy, angry, sad and neutral) in the left hemisphere of 21 two-month-old infants using diffuse optical tomography. Reconstructed total hemoglobin (HbT) images were analysed using adaptive voxel-based clustering and region-of-interest (ROI) analysis. We found a distributed happy > neutral response within the temporo-parietal cortex, peaking in the anterior temporal cortex; a negative HbT response to emotional speech (the average of the emotional speech conditions < baseline) in the temporo-parietal cortex, neutral > angry in the anterior superior temporal sulcus (STS), happy > angry in the superior temporal gyrus and posterior superior temporal sulcus, angry < baseline in the insula, superior temporal sulcus and superior temporal gyrus and happy < baseline in the anterior insula. These results suggest that left STS is more sensitive to happy speech as compared to angry speech, indicating that it might play an important role in processing positive emotions in two-month-old infants. Furthermore, happy speech (relative to neutral) seems to elicit more activation in the temporo-parietal cortex, thereby suggesting enhanced sensitivity of temporo-parietal cortex to positive emotional stimuli at this stage of infant development. - Imaging affective and non-affective touch processing in two-year-old children
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-05-01) Maria, Ambika; Hirvi, Pauliina; Kotilahti, Kalle; Heiskala, Juha; Tuulari, Jetro J.; Karlsson, Linnea; Karlsson, Hasse; Nissilä, IlkkaTouch is an important component of early parent-child interaction and plays a critical role in the socio-emotional development of children. However, there are limited studies on touch processing amongst children in the age range from one to three years. The present study used frequency-domain diffuse optical tomography (DOT) to investigate the processing of affective and non-affective touch over left frontotemporal brain areas contralateral to the stimulated forearm in two-year-old children. Affective touch was administered by a single stroke with a soft brush over the child's right dorsal forearm at 3 cm/s, while non-affective touch was provided by multiple brush strokes at 30 cm/s. We found that in the insula, the total haemoglobin (HbT) response to slow brushing was significantly greater than the response to fast brushing (slow > fast). Additionally, a region in the postcentral gyrus, Rolandic operculum and superior temporal gyrus exhibited greater response to fast brushing than slow brushing (fast > slow). These findings confirm that an adult-like pattern of haemodynamic responses to affective and non-affective touch can be recorded in two-year-old subjects using DOT. To improve the accuracy of modelling light transport in the two-year-old subjects, we used a published age-appropriate atlas and deformed it to match the exterior shape of each subject's head. We estimated the combined scalp and skull, and grey matter (GM) optical properties by fitting simulated data to calibrated and coupling error corrected phase and amplitude measurements. By utilizing a two-compartment cerebrospinal fluid (CSF) model, the accuracy of estimation of GM optical properties and the localization of activation in the insula was improved. The techniques presented in this paper can be used to study neural development of children at different ages and illustrate that the technology is well-tolerated by most two-year-old children and not excessively sensitive to subject movement. The study points the way towards exciting possibilities in functional imaging of deeper functional areas near sulci in small children. - Improved utilization of frequency-domain data for optical tomographic imaging of the human brain
A4 Artikkeli konferenssijulkaisussa(2023) Hirvi, Pauliina; Nissilä, Ilkka; Maria, Ambika; Fang, Qianqian; Kotilahti, Kalle; Heiskala, Juha; Tuulari, Jetro J.; Karlsson, Linnea; Hannukainen, Antti; Karlsson, Hasse; Hyvönen, NuuttiFrequency-domain (FD) optical tomography instruments modulate the intensity of the light source at a radio frequency and measure the amplitude and phase shift of the detected photon density wave. The differing spatial sensitivities of amplitude and phase to the optical properties of tissue suggest that inclusion of phase data can improve the image reconstruction accuracy. This study describes our methodology for improved use of FD data in conjunction with a Monte Carlo (MC) forward solver (Monte Carlo eXtreme; MCX) and a voxel-based model of a two-year-old child’s head. The child participated our previous study where subjects were stimulated with affective (slow brushing) and non-affective touch (fast brushing) to their right forearm, and the responses were measured from the left hemisphere with our in-house 16-channel high-density FD system. We implemented the computation of the FD sensitivity profiles to the MCX photon simulation software, and validated the output against our in-house MC code. We used simulated and the real experimental touch response data to observe the effects of including both FD data types to the image reconstruction instead of amplitude data alone. For the simulated and experimental case, we observed that the inclusion of phase data increases the reconstructed contrast in the brain. The individual touch responses showed similarity to the group-level results in our original publication with 16 subjects and amplitude data alone, and other literature. - Relationship between maternal pregnancy-related anxiety and infant brain responses to emotional speech – a pilot study
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-02-01) Maria, Ambika; Nissilä, Ilkka; Shekhar, Shashank; Kotilahti, Kalle; Tuulari, Jetro J.; Hirvi, Pauliina; Huotilainen, Minna; Heiskala, Juha; Karlsson, Linnea; Karlsson, HasseBackground: Maternal pregnancy-related anxiety (PRA) is reportedly related to neurodevelopmental outcomes of infants. However, the relationship between maternal PRA and the processing of emotions in the infant brain has not been extensively studied with neuroimaging. The objective of the present pilot study is to investigate the relationship between maternal PRA and infant hemodynamic responses to emotional speech at two months of age. Methods: The study sample included 19 mother-infant dyads from a general sample of a population of Caucasian mothers. Self-reported Pregnancy-Related Anxiety Questionnaire (PRAQ-R2) data was collected from mothers during pregnancy at gestational weeks (gwks) 24 (N = 19) and 34 (N = 18). When their infants were two months old, the infants’ brains functional responses to emotional speech in the left fronto-temporoparietal cortex were recorded using diffuse optical tomography (DOT). Results: Maternal PRAQ-R2 scores at gwk 24 correlated negatively with the total hemoglobin (HbT) responses to sad speech on both sides of the temporoparietal junction (Spearman's rank correlation coefficient ρ = -0.87). The correlation was significantly greater at gwk 24 than gwk 34 (ρ = -0.42). Limitations: The field of view of the measurement did not include the right hemisphere or parts of the frontal cortex. The sample size is moderate and the mothers were relatively highly educated, thus there may be some differences between the study sample and the general population. Conclusions: Maternal pregnancy-related anxiety may affect child brain emotion processing development. Further research is needed to understand the functional and developmental significance of the findings.