Stanford Advisors

Contact

  • Academic
    mtwscott@stanford.edu
    University - Scholar Department: Psychology Position: Postdoctoral Scholar

Additional Info

  • Mail Code: 2130

All Publications

  • Visual Field Asymmetries in Responses to ON and OFF Pathway Biasing Stimuli. Visual neuroscience Scott, M. T., Yakovleva, A., Norcia, A. M. 2024; 41: E007

    Abstract

    Recent reports suggest the ON and OFF pathways are differentially susceptible to selective vision loss in glaucoma. Thus, perimetric assessment of ON- and OFF-pathway function may serve as a useful diagnostic. However, this necessitates a developed understanding of normal ON/OFF pathway function around the visual field and as a function of input intensity. Here, using electroencephalography, we measured ON- and OFF-pathway biased contrast response functions in the upper and lower visual fields. Using the steady-state visually evoked potential paradigm, we flickered achromatic luminance probes according to a saw-tooth waveform, the fast phase of which biased responses towards the ON or OFF pathways. Neural responses from the upper and lower visual fields were simultaneously measured using frequency tagging - probes in the upper visual field modulated at 3.75 Hz, while those in the lower visual field modulated at 3 Hz. We find that responses to OFF/decrements are larger than ON/increments, especially in the lower visual field. In the lower visual field, both ON and OFF responses were well described by a sigmoidal non-linearity. In the upper visual field, the ON pathway function was very similar to that of the lower, but the OFF pathway function showed reduced saturation and more cross-subject variability. Overall, this demonstrates that the relationship between the ON and OFF pathways depends on the visual field location and contrast level, potentially reflective of natural scene statistics.

    View details for DOI 10.1017/S095252382400004X

    View details for PubMedID 39698978

  • Glaucoma classification through SSVEP derived ON- and OFF-pathway features. medRxiv : the preprint server for health sciences Scott, M. T., Xu, H., Yakovleva, A., Tibshirani, R., Goldberg, J. L., Norcia, A. M. 2024

    Abstract

    Recent evidence from small animal models and human electrophysiology suggests that the OFF-pathway is more vulnerable to glaucomatous insult than the ON-pathway. Thus, OFF-pathway based measurements of visual function may be useful in the diagnosis of Glaucoma. The steady-state visually evoked potential (SSVEP) can be used to non-invasively make such functional measurements. Here, we examine whether OFF- and ON-pathway biasing SSVEP measurements differently predict glaucoma diagnosis using a large cohort of 98 glaucoma patients and 71 controls. Using both a logistic regression with k-fold cross-validation and a random forest classifier, we show that OFF-pathway biasing features produce a small improvement in predictive accuracy over ON-pathway biasing features. However, despite our inclusion of many more response features and the retention of both participants' eyes, our classifier did not perform as well as previous reports that used the isolated-check VEP. This is likely a result of the relatively small amount of data we collected for each participant, but may also be explained by the absence of any train-test splitting in preexisting work. Nevertheless, our results support further exploration of the diagnostic potential of OFF-pathway biasing functional biomarkers for glaucoma.

    View details for DOI 10.1101/2024.08.22.24312443

    View details for PubMedID 39228700

    View details for PubMedCentralID PMC11370506

  • Use of31P magnetisation transfer magnetic resonance spectroscopy to measure ATP changes after 670nm transcranial photobiomodulation in older adults. Aging cell Fear, E. J., Torkelsen, F. H., Zamboni, E., Chen, K., Scott, M., Jeffery, G., Baseler, H., Kennerley, A. J. 2023: e14005

    Abstract

    Mitochondrial function declines with age, and many pathological processes in neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Using 31 P magnetisation transfer magnetic resonance spectroscopy (MT-MRS) we quantify, for the first time, the effects of 670nm PBM treatment on healthy ageing human brains. We find a significant increase in the rate of ATP synthase flux in the brain after PBM in a cohort of older adults. Our study provides initial evidence of PBM therapeutic efficacy for improving mitochondrial function and restoring ATP flux with age, but recognises that wider studies are now required to confirm any resultant cognitive benefits.

    View details for DOI 10.1111/acel.14005

    View details for PubMedID 37803929

  • Different contrast response functions for sawtooth stimulation favoring ON vs OFF visual pathways in the upper and lower visual fields Scott, M., Yakovleva, A., Norcia, A. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2023

    View details for Web of Science ID 001053758300115