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Chen H, Cui L, Chen S, Liu R, Pan X, Zhou F, Xing Y. Comparable dynamic cerebral autoregulation and neurovascular coupling of the posterior cerebral artery between healthy men and women. CNS Neurosci Ther 2024; 30:e14584. [PMID: 38421125 PMCID: PMC10851316 DOI: 10.1111/cns.14584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/01/2023] [Accepted: 12/18/2023] [Indexed: 03/02/2024] Open
Abstract
AIMS Most studies focus on dynamic cerebral autoregulation (dCA) in the middle cerebral artery (MCA), and few studies investigated neurovascular coupling (NVC) and dCA in the posterior cerebral artery (PCA). We investigated NVC and dCA of the PCA in healthy volunteers to identify sex differences. METHODS Thirty men and 30 age-matched women completed dCA and NCV assessments. The cerebral blood flow velocity (CBFV) and mean arterial pressure were evaluated using transcranial Doppler ultrasound and a servo-controlled plethysmograph, respectively. The dCA parameters were analyzed using transfer function analysis. The NCV was evaluated by eyes-open and eyes-closed (24 s each) periodically based on voice prompts. The eyes-open visual stimulation comprised silent reading of Beijing-related tourist information. RESULTS The PCA gain was lower than that of the MCA in all frequency ranges (all p < 0.05). Phase was consistent across the cerebrovascular territories. The cerebrovascular conductance index (CVCi) and mean CBFV (MV) of the PCA were significantly higher during the eyes-open than eyes-closed period (CVCi: 0.50 ± 0.12 vs. 0.38 ± 0.10; MV: 42.89 ± 8.49 vs. 32.98 ± 7.25, both p < 0.001). The PCA dCA and NVC were similar between the sexes. CONCLUSION We assessed two major mechanisms that maintain cerebral hemodynamic stability in healthy men and women. The visual stimulation-evoked CBFV of the PCA was significantly increased compared to that during rest, confirming the activation of NVC. Men and women have similar functions in PCA dCA and NCV.
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Affiliation(s)
- Hongxiu Chen
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Liuping Cui
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Songwei Chen
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Ran Liu
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Xijuan Pan
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Fubo Zhou
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
| | - Yingqi Xing
- Department of Vascular UltrasonographyXuanwu Hospital, Capital Medical UniversityBeijingChina
- Beijing Diagnostic Center of Vascular UltrasoundBeijingChina
- Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain DisordersCapital Medical UniversityBeijingChina
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Toosi T, Issa EB. Brain-like Flexible Visual Inference by Harnessing Feedback-Feedforward Alignment. ARXIV 2023:arXiv:2310.20599v1. [PMID: 37961740 PMCID: PMC10635293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In natural vision, feedback connections support versatile visual inference capabilities such as making sense of the occluded or noisy bottom-up sensory information or mediating pure top-down processes such as imagination. However, the mechanisms by which the feedback pathway learns to give rise to these capabilities flexibly are not clear. We propose that top-down effects emerge through alignment between feedforward and feedback pathways, each optimizing its own objectives. To achieve this co-optimization, we introduce Feedback-Feedforward Alignment (FFA), a learning algorithm that leverages feedback and feedforward pathways as mutual credit assignment computational graphs, enabling alignment. In our study, we demonstrate the effectiveness of FFA in co-optimizing classification and reconstruction tasks on widely used MNIST and CIFAR10 datasets. Notably, the alignment mechanism in FFA endows feedback connections with emergent visual inference functions, including denoising, resolving occlusions, hallucination, and imagination. Moreover, FFA offers bio-plausibility compared to traditional back-propagation (BP) methods in implementation. By repurposing the computational graph of credit assignment into a goal-driven feedback pathway, FFA alleviates weight transport problems encountered in BP, enhancing the bio-plausibility of the learning algorithm. Our study presents FFA as a promising proof-of-concept for the mechanisms underlying how feedback connections in the visual cortex support flexible visual functions. This work also contributes to the broader field of visual inference underlying perceptual phenomena and has implications for developing more biologically inspired learning algorithms.
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Affiliation(s)
- Tahereh Toosi
- Center for Theoretical Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
| | - Elias B. Issa
- Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
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Chen S, Chen H, Duan J, Cui L, Liu R, Xing Y. Impaired Dynamic Cerebral Autoregulation in Patients With Cerebral Venous Sinus Thrombosis: Evaluation Using Transcranial Doppler and Silent Reading Stimulation. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:2221-2226. [PMID: 37532632 DOI: 10.1016/j.ultrasmedbio.2023.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/21/2023] [Accepted: 07/11/2023] [Indexed: 08/04/2023]
Abstract
OBJECTIVE Cerebral venous sinus thrombosis (CVST) may impair dynamic cerebral autoregulation (dCA) of the middle cerebral artery (MCA). However, most studies have focused on dCA of the MCA; a few studies are based on the posterior cerebral artery (PCA) during silent reading and neurovascular coupling (NVC). This study explored the effects of CVST on dCA of the MCA and PCA during silent reading and NVC. METHODS From January 2021 to August 2022, 60 CVST patients and 30 controls were enrolled in this study. Non-invasive continuous beat-to-beat blood pressure, cerebral blood flow velocity and other associated information on the MCA and PCA during silent reading were collected using a transcranial Doppler. NVC assessment was performed by opening and closing the eyes periodically based on voice prompts, and eye-opening visual stimulation was achieved by silently reading Chinese tourism materials. Visual stimulation signals can selectively activate Brodmann's areas 17, 18, and 19 of the occipital when reading silently with open eyes, prompting them to release neurotransmitters and dilate PCA. dCA was determined by transfer function analysis. RESULTS In dCA of the PCA during silent reading, the CVST group's very low frequency phase was lower than that of the control group (p = 0.047). In NVC, the difference in the indexes of the cerebrovascular conductance and visually evoked flow response of the CVST group were lower than those of the control group (p = 0.017 and p = 0.019, respectively). CONCLUSION Compared with the control group, dCA and NVC of the PCA during silent reading were impaired in CVST patients.
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Affiliation(s)
- Songwei Chen
- Department of Vascular Ultrasonography, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Diagnostic Center of Vascular Ultrasound, Beijing, China; Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Hongxiu Chen
- Department of Vascular Ultrasonography, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Diagnostic Center of Vascular Ultrasound, Beijing, China; Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Jiangang Duan
- Department of Emergency, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Liuping Cui
- Department of Vascular Ultrasonography, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Diagnostic Center of Vascular Ultrasound, Beijing, China; Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Ran Liu
- Department of Vascular Ultrasonography, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Diagnostic Center of Vascular Ultrasound, Beijing, China; Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Yingqi Xing
- Department of Vascular Ultrasonography, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Diagnostic Center of Vascular Ultrasound, Beijing, China; Center of Vascular Ultrasonography, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China.
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