Neuro-ophthalmology
Mostafa Khalil, Omar Kouli in The Duke Elder Exam of Ophthalmology, 2019
The optic radiations connect the LGN to the occipital lobe. Superior optic radiations, representing the inferior visual field quadrants, pass through the parietal lobe and terminate at the primary visual cortex (also known as V1 or Brodmann area 17) in the occipital lobe, superior to the calcarine sulcus (cuneus gyrus). The inferior optic radiations (Meyer's loop), representing the superior visual field quadrants, pass through the temporal lobe and terminate at the primary visual cortex, inferior to the calcarine sulcus (lingual gyrus). The macula is represented posteriorly just lateral to the tip of the calcarine sulcus.
Neuro-Ophthalmological Findings in Patients with Posterior Circulation Stroke
Vivek Lal in A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Patients with occipital cortex lesions may have partial hemianopic field defects in which larger and brighter stimuli are perceived, but small dimmer stimuli are not. In contrast, lesions affecting the geniculocalcarine tracts often cause dense complete defects for all visual stimuli in the affected parts of the visual fields. Small occipital lobe infarcts can cause homonymous scotomas that are typically congruent. When the lesions are near the occipital pole, the scotomas are usually within the perimacular, central fixation area. More anterior lesions are likely to cause more peripherally placed scotomas above or below the horizontal meridian. The unpaired monocular temporal crescent of vision and the more peripheral portions of the contralateral visual fields project onto the cerebral cortex within the depth of the calcarine fissure.2 When infarction spares the most anterior portion of the calcarine cortex, the resulting hemianopia may not be congruent and may spare the temporal crescent of vision in the eye contralateral to the infarct. Rarely, a very far anterior, small occipital lobe infarct can involve only the temporal crescent in the contralateral eye. Homonymous sector and quadrant defects are also common. A homonymous superior quadrantanopia is caused by a lesion involving the contralateral lower bundle of the optic radiations either in Meyer's loop in the temporal lobe near the temporal horn of the lateral ventricle or in the occipital lobe affecting the striate cortex on the lower bank of the calcarine fissure (Figure 23.2). A homonymous inferior quadrantanopia is usually due to a deep parietal lobe lesion involving the upper bundle of the optic radiations or the upper bank of the calcarine cortex in the cuneus (Figure 23.3). Visual inattention and neglect of the contralateral visual field is common in patients with large unilateral infarcts.
The viva: operative surgery and surgical anatomy
Vivian A. Elwell, Ramez Kirollos, Syed Al-Haddad in Neurosurgery, 2014
The lateral part of the sulcus is situated about 5 cm in front of the occipital pole. The medial part runs downward and forward as a deep cleft on the medial surface of the hemisphere, and joins the calcarine fissure below and behind the posterior end of the corpus callosum. In most cases it contains a submerged gyrus. It marks the boundary between the cuneus and precuneus, and also between the parietal and occipital lobes. It is located approximately in line with the lambdoid suture.
Altered brain activity and functional connectivity in migraine without aura during and outside attack
Published in Neurological Research, 2023
Luping Zhang, Wenjing Yu, Zhengxiang Zhang, Maosheng Xu, Feng Cui, Wenwen Song, Zhijian Cao
The MWoA-DI patients also showed decreased ALFF with peaks in the right cuneus extended to the right calcarine and superior occipital gyrus. Furthermore, the ALFF value in this region was negatively correlated with the MIDAS score in MWoA-DI patients. These results showed that MWoA-DI patients had impaired right calcarine functions, which may be related to the disease severity. The cuneus is within the extrastriate cortex and is classically related to visual information processing. Besides, it is related to multisensory integration and cognitive processing, including attention, learning, and memory [28]. It is thought that the cuneus is involved in pain processing [29], and cortical thinning and altered cuneus function have been demonstrated in other pain conditions [30–32]. There is evidence that cuneus is involved in the pathophysiology of migraine. A morphometry study found that compared with HC, MWoA-DI patients have reduced cortical thickness in the cuneus [33]. Related studies found that compared with HC, cuneus activation is lower in migraine patients during the interictal phase [34,35]. In addition, our correlation analysis suggested that the degree of cuneus function impairment increased with the disease severity. Thus, the dysfunctioning of the cuneus in the interictal phase may serve as the risk factor for severe migraine attacks.
Functional connectivity from dorsolateral prefrontal cortex mediates the impact of social jetlag on depressive tendency in young adults
Published in Chronobiology International, 2023
Yan Jia, Yun Tian, Haien Wang, Xu Lei
The cuneus also participates in visuospatial processing and visual association as a component of the visual cortex (Kunimatsu et al. 2020). Long-range projections from the prefrontal lobe have been demonstrated to regulate neural activity in sensory brain regions, and frontal-occipital neuronal connections have been linked to the processing of visual stimuli (Zhang et al. 2016). This disrupted neuronal connection in depressed patients causes defective top-down attentional control, which results in improper information filtering in the visual cortex (Desseilles et al. 2009). One of the cognitive factors causing and maintaining depression problems is the inability to allocate attention to the appropriate emotional cues (Disner et al. 2011). Furthermore, reduced functional connectivity of the cuneus was found in depressed individuals with low sleep efficiency, suggesting that functional abnormalities of the cuneus may underlie impaired visual information processing in sleep disorders co-morbid with depression (Zhu et al. 2020).
Cortical and cerebellar structural correlates of cognitive-motor integration performance in females with and without persistent concussion symptoms
Published in Brain Injury, 2023
Johanna M. Hurtubise, Diana J. Gorbet, Loriann Hynes, Alison K. Macpherson, Lauren E. Sergio
In addition, the volume and thickness of cortical regions of interest were examined. These regions were determined a-priori and known to be involved in the frontoparietal network for visually guided reaching (28,48,49). Regions in the parietal lobe included the right and left superior parietal lobe (SPL), inferior parietal lobe (IPL), and precuneus. In the frontal lobe, regions of interest included the right and left precentral, superior frontal, rostral middle frontal (rMFG), and caudal middle frontal (cMFG) regions. Finally, the cuneus, which is a region within the occipital lobe, was also investigated. Both the thickness and volume were extracted from each subject using the Desikan-Killiany cortical parcellation atlas (50). The cortical parcellation of the FreeSurfer template was mapped back onto the individual subject and adjusted for small variations. The values of each individual subject’s thickness and volume of the aforementioned regions were then extracted and structural volumes were corrected for TIV using a proportion method.
Related Knowledge Centers
- Calcarine Sulcus
- Pyramidal Cell
- Visual Cortex
- Occipital Lobe
- Brain
- Parieto-Occipital Sulcus