کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5631148 1580855 2017 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The hemodynamic signal as a first-order low-pass temporal filter: Evidence and implications for neuroimaging studies
ترجمه فارسی عنوان
سیگنال همودینامیک به عنوان فیلتر فوری زمانبندی کم نور در درجه اول: شواهد و پیامدهای مطالعات تصویربرداری عصبی
موضوعات مرتبط
علوم زیستی و بیوفناوری علم عصب شناسی علوم اعصاب شناختی
چکیده انگلیسی


- The dynamics of functional maps in V1 follows a first-order differential equation.
- This alters the recorded signals in response to periodic continuous stimulation.
- Phase shifts and attenuation change with stimulus frequencies in Fourier space.
- Inverting this filter allows recovering accurate orientation and direction maps.

Neuronal activation triggers local changes in blood flow and hemoglobin oxygenation. These hemodynamic signals can be recorded through functional magnetic resonance imaging or intrinsic optical imaging, and allows inferring neural activity in response to stimuli. These techniques are widely used to uncover functional brain architectures. However, their accuracy suffers from distortions inherent to hemodynamic responses and noise. The analysis of these signals currently relies on models of impulse hemodynamic responses to brief stimuli. Here, in order to infer precise functional architectures, we focused on integrated signals associated to the dynamic response of functional maps. To this end, we recorded orientation and direction maps in cat primary visual cortex and compared two protocols: the conventional episodic stimulation technique and a continuous, periodic stimulation paradigm. Conventional methods show that the dynamics of activation and deactivation of the functional maps follows a linear first-order differential equation representing a low-pass filter. Comparison with the periodic stimulation methods confirmed this observation: the phase shifts and magnitude attenuations extracted at various frequencies were consistent with a low-pass filter with a 5 s time constant. This dynamics presumably reflects the variations in deoxyhemoglobin mediated by arterial dilations. This dynamics open new avenues in the analysis of neuroimaging data that differs from common methods based on the hemodynamic response function. In particular, we demonstrate that inverting this first-order low-pass filter minimized the distortions of the signal and enabled a much faster and accurate reconstruction of functional maps.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: NeuroImage - Volume 155, 15 July 2017, Pages 394-405
نویسندگان
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