Cecil Chern-Chyi Yen1, Fuqiang Zhao2, Seong-Gi Kim3, 4
1National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States; 2Imaging, Merck, West Point, PA, United States; 3Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 4Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
Cortical layer-specific responses are shown to resemble the neural response of the cortical layers. However, these layer-specific hemodynamic responses may be contaminated by the vascular reactivity, which is known to have layer-specific distribution. To investigate this issue, we performed two cerebral blood volume (CBV)- weighted fMRI studies in cat visual cortex with hypercapnic stimulus as an indicator for vascular reactivity, and visual stimulus. Our results showed that the peak responses of the CBV-weighted layer profile induced by hypercapnic stimulus co-localized with that induced by visual stimulus. Therefore, cautions shall be taken in interpreting layer-specific hemodynamic response as neural response.