Functional topography of pulvinar–visual cortex networks in macaques revealed by INS–fMRI

• Published in: Journal of comparative neurology (1911) 2023-04, Vol.531 (6), p.681-700
• Main Authors: Yao, Songping, Shi, Sunhang, Zhou, Qiuying, Wang, Jianbao, Du, Xiao, Takahata, Toru, Roe, Anna Wang
• Format: Article
• Language: English
• Subjects: Animals; brain connectome; Brain Mapping - methods; Functional magnetic resonance imaging; infrared laser; Macaca; Macaca mulatta; Magnetic Resonance Imaging; Neuroimaging; Pulvinar; Pulvinar - physiology; pulvinar nucleus; Visual cortex; Visual Cortex - diagnostic imaging; Visual Cortex - physiology; Visual pathways; Visual Pathways - diagnostic imaging; Visual Pathways - physiology
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.25456

The pulvinar in the macaque monkey contains three divisions: the medial pulvinar (PM), the lateral pulvinar (PL), and the inferior pulvinar (PI). Anatomical studies have shown that connections of PM are preferentially distributed to higher association areas, those of PL are biased toward the ventral visual pathway, and those of PI are biased with the dorsal visual pathway. To study functional connections of the pulvinar at mesoscale, we used a novel method called INS–fMRI (infrared neural stimulation and functional magnetic resonance imaging). This method permits studies and comparisons of multiple pulvinar networks within single animals. As previously revealed, stimulations of different sites in PL and PI produced topographically organized focal activations in visual areas V1, V2, and V3. In contrast, PM stimulation elicited little or diffuse response. The relative activations of areas V1, V2, V3A, V3d, V3v, V4, MT, and MST revealed that connections of PL are biased to ventral pathway areas, and those of PI are biased to dorsal areas. Different statistical values of activated blood‐oxygen‐level‐dependent responses produced the same center of activation, indicating stability of connectivity; it also suggests possible dynamics of broad to focal responses from single stimulation sites. These results demonstrate that infrared neural stimulation‐induced connectivity is largely consistent with previous anatomical connectivity studies, thereby demonstrating validity of our novel method. In addition, it suggests additional interpretations of functional connectivity to complement anatomical studies. We have employed a novel method combining infrared laser neural stimulation (INS) and fMRI to study functional networks from the pulvinar to the visual cortex at mesoscale in vivo. We show that stimulations of different sites in the pulvinar produced topographically organized focal BOLD activations in visual areas. When the stimulation sites moved slightly (as shown in the upper panel of the graphical , sites a and b) in the pulvinar, the BOLD responses observed in the visual cortex shifted accordingly (lower panel).