Journal Article

Extremely fast pRF mapping for real-time applications

Senden, Mario, Bhat, Salil, Lührs, Michael, Goebel, Rainer

2021

Overview

•Mapping of population receptive_fields within seconds for millions of voxels.•Online estimation of receptive_fields using gradient-descent.•Fast pRF parameter estimation for real-time applications.•Model-free approach for pRF mapping. Population receptive field (pRF) mapping is a popular tool in computational neuroimaging that allows for the investigation of receptive field properties, their topography and interrelations in health and disease. Furthermore, the possibility to invert population receptive fields provides a decoding model for constructing stimuli from observed cortical activation patterns. This has been suggested to pave the road towards pRF-based brain-computer interface (BCI) communication systems, which would be able to directly decode internally visualized letters from topographically organized brain activity. A major stumbling block for such an application is, however, that the pRF mapping procedure is computationally heavy and time consuming. To address this, we propose a novel and fast pRF mapping procedure that is suitable for real-time applications. The method is built upon hashed-Gaussian encoding of the stimulus, which tremendously reduces computational resources. After the stimulus is encoded, mapping can be performed using either ridge regression for fast offline analyses or gradient descent for real-time applications. We validate our model-agnostic approach in silico, as well as on empirical fMRI data obtained from 3T and 7T MRI scanners. Our approach is capable of estimating receptive fields and their parameters for millions of voxels in mere seconds. This method thus facilitates real-time applications of population receptive field mapping.

• Publisher: Elsevier Inc,Elsevier Limited,Elsevier
• Subject: Adult / Alzheimer's disease / Brain / Brain mapping / Brain Mapping - methods / Brain-Computer Interfaces / Communications systems / Computational neuroscience / Computer applications / Functional magnetic resonance imaging / Humans / Image Processing, Computer-Assisted - methods / Implants / Magnetic Resonance Imaging - methods / Male / Models, Neurological / Movement Disorders / Neural networks / Neuroimaging / Normal Distribution / Photic Stimulation - methods / Population receptive field mapping / Real-time fMRI / Receptive field / Stimulus encoding / Vision / Visual Cortex / Visual Fields