MacFarlane, Duncan L.

Permanent URI for this collectionhttps://hdl.handle.net/10735.1/2797

Dr. Duncan L. MacFarlane is Professor of Electrical Engineering. His research interests include

  • Photonics Devices and Systems
  • Advanced Displays
  • Optical Communications
Learn more about Dr. MacFarlane on his home and Research Explorer pages.

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Browsing MacFarlane, Duncan L. by Title

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    Evaluation of Cortical Plasticity in Children with Cerebral Palsy Undergoing Constraint-Induced Movement Therapy Based on Functional Near-Infrared Spectroscopy
    Cao, Jianwei; Khan, Bilal; Hervey, Nathan; Tian, Fenghua; Delgado, Mauricio R.; Clegg, Nancy J.; Smith, Linsley; Roberts, Heather; Tulchin-Francis, Kirsten; Shierk, Angela; Shagman, Laura; MacFarlane, Duncan L.; Liu, Hanli; Alexandrakis, George; 7202978565 (MacFarlane, DL)
    Sensorimotor cortex plasticity induced by constraint-induced movement therapy (CIMT) in six children (10.2 +/- 2.1 years old) with hemiplegic cerebral palsy was assessed by functional near-infrared spectroscopy (fNIRS). The activation laterality index and time-to-peak/duration during a finger-tapping task and the resting-state functional connectivity were quantified before, immediately after, and 6 months after CIMT. These fNIRS-based metrics were used to help explain changes in clinical scores of manual performance obtained concurrently with imaging time points. Five age-matched healthy children (9.8 +/- 1.3 years old) were also imaged to provide comparative activation metrics for normal controls. Interestingly, the activation time-to-peak/duration for all sensorimotor centers displayed significant normalization immediately after CIMT that persisted 6 months later. In contrast to this improved localized activation response, the laterality index and resting-state connectivity metrics that depended on communication between sensorimotor centers improved immediately after CIMT, but relapsed 6 months later. In addition, for the subjects measured in this work, there was either a trade-off between improving unimanual versus bimanual performance when sensorimotor activation patterns normalized after CIMT, or an improvement occurred in both unimanual and bimanual performance but at the cost of very abnormal plastic changes in sensorimotor activity.
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    Improving Optical Contact for Functional Near-Infrared Brain Spectroscopy and Imaging with Brush Optodes
    Khan, B.; Wildey, C.; Francis, Robert; Tian, F.; Delgado, M. R.; Liu, H.; MacFarlane, Duncan L.; Alexandrakis, G.
    A novel brush optode was designed and demonstrated to overcome poor optical contact with the scalp that can occur during functional near infrared spectroscopy (fNIRS) and imaging due to light obstruction by hair. The brush optodes were implemented as an attachment to existing commercial flat-faced (conventional) fiber bundle optodes. The goal was that the brush optodes would thread through hair and improve optical contact on subjects with dense hair. Simulations and experiments were performed to assess the magnitude of these improvements. FNIRS measurements on 17 subjects with varying hair colors (blonde, brown, and black) and hair densities (0-2.96 hairs/mm 2) were performed during a finger tapping protocol for both flat and brush optodes. In addition to reaching a study success rate of almost 100% when using the brush optode extensions, the measurement setup times were reduced by a factor of three. Furthermore, the brush optodes enabled improvements in the activation signal-to-noise ratio (SNR) by up to a factor of ten as well as significant (p < 0.05) increases in the detected area of activation (dAoA). The measured improvements in SNR were matched by Monte Carlo (MC) simulations of photon propagation through scalp and hair. In addition, an analytical model was derived to mathematically estimate the observed light power losses due to different hair colors and hair densities. Interestingly, the derived analytical formula produced excellent estimates of the experimental data and MC simulation results despite several simplifying assumptions. The analytical model enables researchers to readily estimate the light power losses due to obstruction by hair for both flat-faced fiber bundles and individual fibers for a given subject. © 2012 Optical Society of America.
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    Optical Architecture Design for Detection of Absorbers Embedded in Visceral Fat
    (Optical Soc Amer) Francis, Robert; Florence, James; MacFarlane, Duncan L.
    Optically absorbing ducts embedded in scattering adipose tissue can be injured during laparoscopic surgery. Non-sequential simulations and theoretical analysis compare optical system configurations for detecting these absorbers. For absorbers in deep scattering volumes, trans-illumination is preferred instead of diffuse reflectance. For improved contrast, a scanning source with a large area detector is preferred instead of a large area source with a pixelated detector.