Recovering sight in adulthood leads to rapid neurofunctional reorganization of visual functions

Reorganization of the structural connectome during vision recovery in pituitary adenoma patients post-transsphenoidal surgery

Pituitary adenomas (PAs) can exert pressure on the optic apparatus, leading to visual impairment. A subset of patients may observe a swift improvement in their vision following surgery. Nevertheless, the alterations in the structural connectome during the early postoperative period remain largely unexplored. The research employed probabilistic tractography, graph theoretical analysis, and statistical methods on preoperative and postoperative structural magnetic resonance imaging and diffusion tensor images from 13 PA patients. Postoperative analysis revealed an increase in global and local efficiency, signifying improved network capacity for parallel information transfer and fault tolerance, respectively. Enhanced clustering coefficient and reduced shortest path length were also observed, suggesting a more regular network organization and shortened communication steps within the brain network. Furthermore, alterations in node graphical properties were detected, implying a restructuring of the network's control points, possibly contributing to more efficient visual processing. These findings propose that rapid vision recovery post-surgery may be associated with significant reorganization of the brain's structural connectome, enhancing the efficiency and adaptability of the network, thereby facilitating improved visual processing.

Study of extravisual resting-state networks in pituitary adenoma patients with vision restoration

Background

Pituitary adenoma (PA) may compress the optic apparatus, resulting in impaired vision. Some patients can experience improved vision rapidly after surgery. During the early period after surgery, however, the change in neurofunction in the extravisual cortex and higher cognitive cortex has yet to be explored.

Objective

Our study focused on the changes in the extravisual resting-state networks in patients with PA after vision restoration.

Methods

We recruited 14 patients with PA who experienced visual improvement after surgery. The functional connectivity (FC) of 6 seeds [auditory cortex (A1), Broca’s area, posterior cingulate cortex (PCC) for the default mode network (DMN), right caudal anterior cingulate cortex for the salience network (SN) and left dorsolateral prefrontal cortex for the executive control network (ECN)] were evaluated. A paired t test was conducted to identify the differences between two groups of patients.

Results

Compared with their preoperative counterparts, patients with PA with improved vision exhibited decreased FC with the right A1 in the left insula lobule, right middle temporal gyrus and left postcentral gyrus and increased FC in the right paracentral lobule; decreased FC with the Broca in the left middle temporal gyrus and increased FC in the left insula lobule and right thalamus; decreased FC with the DMN in the right declive and right precuneus; increased FC in right Brodmann area 17, the left cuneus and the right posterior cingulate; decreased FC with the ECN in the right posterior cingulate, right angular and right precuneus; decreased FC with the SN in the right middle temporal gyrus, right hippocampus, and right precuneus; and increased FC in the right fusiform gyrus, the left lingual gyrus and right Brodmann area 19.

Conclusions

Vision restoration may cause a response of cross-modal plasticity and multisensory systems related to A1 and the Broca. The DMN and SN may be involved in top-down control of the subareas within the visual cortex. The precuneus may be involved in the DMN, ECN and SN simultaneously.

Study of rapid reorganization of visual neurofunctions with the resting-state functional MRI in pituitary adenoma patients with vision improvement after transsphenoidal surgery

INTRODUCTION

To investigate changes of vision-related resting-state activity in pituitary adenoma (PA) patients with visual improvement after transsphenoidal surgery.

METHODS

14 PA patients with visual improvement after surgery were enrolled. The resting-state functional MRI and neuro-ophthalmologic evaluation were performed before and after the operation. The functional connectivity (FC) of 8 seeds (the primary visual cortex (V1), the secondary visual cortex (V2), the middle temporal visual cortex (MT+), and fusiform gyrus(FG)) was evaluated. A paired t test was conducted to identify the differences between the two groups.

RESULTS

Compared with the preoperation counterparts, the PA patients with improved vision exhibited decreased FC with the V1, V2, MT+, FG in the left paracentral lobule, bilateral lingual gyrus, precentral gyrus(BA 4), right superior temporal gyrus(BA 22), left fusiform gyrus, bilateral middle occipital gyrus (BA 19), left cuneus, right inferior occipital gyrus, left superior frontal gyrus, right cuneus, left superior parietal lobule(BA 7),the medulla, right postcentral gyrus, and increased FC in the right middle frontal gyrus, left inferior parietal lobule (BA 40), left declive, right lentiform nucleus, inferior frontal gyrus, right superior frontal gyrus(BA 11), cingulate gyrus(BA 32), right putamen, right thalamus, left medial frontal gyrus, left claustrum, left superior frontal Medial, right rectal gyrus(BA 25) and right parahippocampal gyrus.

CONCLUSIONS

The results show most subareas within the visual cortex exhibit decreased functional connectivity. The functional changes in subareas within default mode network (DMN), action observation network (AON) and the multisensory system in PAs propose that vision improvement may lead to function remodeling in higher-order cortex.

Altered Vision-Related Resting-State Activity in Pituitary Adenoma Patients with Visual Damage

Objective

To investigate changes of vision-related resting-state activity in pituitary adenoma (PA) patients with visual damage through comparison to healthy controls (HCs).

Methods

25 PA patients with visual damage and 25 age- and sex-matched corrected-to-normal-vision HCs underwent a complete neuro-ophthalmologic evaluation, including automated perimetry, fundus examinations, and a magnetic resonance imaging (MRI) protocol, including structural and resting-state fMRI (RS-fMRI) sequences. The regional homogeneity (ReHo) of the vision-related cortex and the functional connectivity (FC) of 6 seeds within the visual cortex (the primary visual cortex (V1), the secondary visual cortex (V2), and the middle temporal visual cortex (MT+)) were evaluated. Two-sample t-tests were conducted to identify the differences between the two groups.

Results

Compared with the HCs, the PA group exhibited reduced ReHo in the bilateral V1, V2, V3, fusiform, MT+, BA37, thalamus, postcentral gyrus and left precentral gyrus and increased ReHo in the precuneus, prefrontal cortex, posterior cingulate cortex (PCC), anterior cingulate cortex (ACC), insula, supramarginal gyrus (SMG), and putamen. Compared with the HCs, V1, V2, and MT+ in the PAs exhibited decreased FC with the V1, V2, MT+, fusiform, BA37, and increased FC primarily in the bilateral temporal lobe (especially BA20,21,22), prefrontal cortex, PCC, insular, angular gyrus, ACC, pre-SMA, SMG, hippocampal formation, caudate and putamen. It is worth mentioning that compared with HCs, V1 in PAs exhibited decreased or similar FC with the thalamus, whereas V2 and MT+ exhibited increased FCs with the thalamus, especially pulvinar.

Conclusions

In our study, we identified significant neural reorganization in the vision-related cortex of PA patients with visual damage compared with HCs. Most subareas within the visual cortex exhibited remarkable neural dysfunction. Some subareas, including the MT+ and V2, exhibited enhanced FC with the thalamic pulvinar, which indicates an important role in the compensatory mechanism following visual impairment. In addition, neural dysfunction within the visual cortex was associated with neural activity alternation in the higher-order cognitive cortex, especially subareas in default mode network (DMN) and salience network (SN).

Changes in the Vision-related Resting-state Network in Pituitary Adenoma Patients After Vision Improvement

Background:

The aim of this research was to investigate the changes in the vision-related resting-state network (V-RSN) in pituitary adenoma (PA) patients after vision improvement, which was induced by operative treatment.

Methods:

Ten PA patients with an improved visual acuity or/and visual field after transsphenoidal pituitary tumor resection were recruited and underwent a complete neuro-ophthalmologic evaluation, as well as an magnetic resonance imaging (MRI) protocol, including structural and resting-state functional MRI sequences before and after the operation. The regional homogeneity (ReHo) of the V-RSN was evaluated. Two sample t-test was performed to identify the significant differences in the V-RSN in the PA patients before and after transsphenoidal pituitary tumor resection.

Results:

Compared with the preoperation counterparts, the PA patients with improved vision after the operation exhibited reduced ReHo in the bilateral thalamus, globus pallidus, caudate nucleus, putamen nucleus, supplementary motor area, and left hippocampal formation, and increased ReHo in the bilateral cuneus gyrus, calcarine gyrus, right lingual gyrus, and fusiform gyrus.

Conclusions:

PA patients with improved vision exhibit increased neural activity within the visual cortex, but decreased neural activity in subareas of the multisensory and multimodal systems beyond the vision cortex.

Impact of blindness onset on the functional organization and the connectivity of the occipital cortex

Contrasting the impact of congenital versus late-onset acquired blindness provides a unique model to probe how experience at different developmental periods shapes the functional organization of the occipital cortex. We used functional magnetic resonance imaging to characterize brain activations of congenitally blind, late-onset blind and two groups of sighted control individuals while they processed either the pitch or the spatial attributes of sounds. Whereas both blind groups recruited occipital regions for sound processing, activity in bilateral cuneus was only apparent in the congenitally blind, highlighting the existence of region-specific critical periods for crossmodal plasticity. Most importantly, the preferential activation of the right dorsal stream (middle occipital gyrus and cuneus) for the spatial processing of sounds was only observed in the congenitally blind. This demonstrates that vision has to be lost during an early sensitive period in order to transfer its functional specialization for space processing toward a non-visual modality. We then used a combination of dynamic causal modelling with Bayesian model selection to demonstrate that auditory-driven activity in primary visual cortex is better explained by direct connections with primary auditory cortex in the congenitally blind whereas it relies more on feedback inputs from parietal regions in the late-onset blind group. Taken together, these results demonstrate the crucial role of the developmental period of visual deprivation in (re)shaping the functional architecture and the connectivity of the occipital cortex. Such findings are clinically important now that a growing number of medical interventions may restore vision after a period of visual deprivation.