Left Visual Field Research Articles

Brain lateralization of face recognition in hearing-impairedindividuals

<p indent=0mm>Adults show the left-visual field/right-hemisphere advantage for the recognition of face. The experience of auditory deprivation and sign language in hearing-impaired individuals could reshape the function and structure of brain. Previous studies suggest that hearing-impaired individuals demonstrate the right-visual field or left-hemisphere superiority for visuospatial attention, visual motion information processing and facial expression processing. The present study aims to further investigate the brain lateralization for face processing in hearing-impaired adults by using behavioral and ERP measures. In experiment 1, the divided visual field paradigm was used and the accuracies and corrected reaction times of face processing in the left-visual field were found to be significantly higher and shorter than those in the right-visual field for hearing individuals, whereas there were no significant differences between left- and right-visual field in hearing-impaired individuals. However, both hearing and hearing-impaired individuals showed the same left-visual field superiority for word processing efficiency. In experiment 2, One-back task and ERPs were used to investigate the brain lateralization of face recognition in hearing and hearing-impaired individuals. The results showed that the N170 amplitude for face processing in the right hemisphere was significantly larger than that in the left hemisphere for hearing individuals. However, there was no significant difference in N170 amplitude between the left and right hemispheres for hearing-impaired individuals. As for word processing, hearing and hearing-impaired individuals both showed a bilateral activation. Therefore, the current study provided converging evidence that the left-visual field or right hemisphere superiority for face processing in hearing-impaired individuals disappeared. These findings not only expand our understanding of the face processing in hearing-impaired individuals, but also help us understand the hemispheric organization for face recognition.

Electrophysiological Correlates of Character Transposition in the Left and Right Visual Fields.

This study examined the brain activity elicited by the hemispheric asymmetries and morpheme transposition of two-character Chinese words (canonical and transposed word) and pseudowords using event-related potentials (ERPs) with a dual-target rapid serial visual presentation (RSVP) task. Electrophysiological results showed facilitation effects for canonical words with centrally presented visual field (CVF) and right visual field (RVF) presentations but not with left visual field (LVF) presentations, as reflected by less negative N400 amplitudes. Moreover, more positive late positive component (LPC) amplitudes were observed for both canonical words and transposed words irrespective of the visual fields. More importantly, transposed words elicited a more negative N400 amplitude and a less positive LPC amplitude compared with the amplitudes elicited by canonical words for CVF and RVF presentations. For LVF presentations, transposed words elicited a less negative N250 amplitude compared with canonical words, and there was no significant difference between canonical words and transposed words in the N400 effect. Taken together, we concluded that character transposition facilitated the mapping of whole-word orthographic representation to semantic information in the LVF, as reflected by the N250 component, and such morpheme transposition influenced whole-word semantic processing in CVF and RVF presentations, as reflected by N400 and LPC components.

Hemifield-Specific Rotational Biases during the Observation of Ambiguous Human Silhouettes

Both static and dynamic ambiguous stimuli representing human bodies that perform unimanual or unipedal movements are usually interpreted as right-limbed rather than left-limbed, suggesting that human observers attend to the right side of others more than the left one. Moreover, such a bias is stronger when static human silhouettes are presented in the RVF (right visual field) than in the LVF (left visual field), which might represent a particular instance of embodiment. On the other hand, hemispheric-specific rotational biases, combined with the well-known bias to perceive forward-facing figures, could represent a confounding factor when accounting for such findings. Therefore, we investigated whether the lateralized presentation of an ambiguous rotating human body would affect its perceived handedness/footedness (implying a role of motor representations), its perceived spinning direction (implying a role of visual representations), or both. To this aim, we required participants to indicate the perceived spinning direction (which also unveils the perceived handedness/footedness) of ambiguous stimuli depicting humans with an arm or a leg outstretched. Results indicated that the lateralized presentation of the stimuli affected both their perceived limb laterality (a larger number of figures being interpreted as right-limbed in the RVF than in the LVF) and their perceived spinning direction (a larger number of figures being interpreted as spinning clockwise in the LVF than in the RVF). However, the hemifield of presentation showed a larger effect size on the perceived spinning direction than on the perceived limb laterality. Therefore, as we already proposed, the implicit representation of others’ handedness seems to be affected more by visual than by motor processes during the perception of ambiguous human silhouettes.

Behavioural and neural effects of eccentricity and visual field during covert visuospatial attention

The attentional priority map plays a key role in the distribution of attention, and is modulated by bottom-up sensory as well as top-down task-dependent factors. The intraparietal sulcus (IPS) is a key candidate to hold a neural representation of the attentional priority map. In the current study, we examined the role of the IPS during covert attention to spatial locations with high or low eccentricity in one or both visual hemifields. To this end, eighteen neurologically healthy participants performed a cued letter discrimination task in which they were endogenously cued to attend to a location at a 5 or 10° eccentricity in the left and/or right visual field. We briefly presented a four-letter target array and subsequently probed perceptual performance while acquiring event-related functional MRI data. While behavioural results showed greater letter discrimination performance at the low eccentricity compared to the high eccentricity location, no neural effect of eccentricity was observed. The results further showed that attending to one visual hemifield produced higher activation in the left parietal and occipital cortex compared to attending bilaterally. Future studies may consider increasing the involvement of top-down control of attention to the cued location to study the neural effect of eccentricity, e.g., through manipulating the task difficulty.

Colour Categorization and its Effect on Perception: A Conceptual Replication.

The presented study examines the question of colour categorization in relation to the hypothesis of linguistic relativity. The study is based on research conducted by Gilbert et al. (2006) and their claim that linguistic colour categorization in a particular language helps colour recognition and speeds the process of colour discrimination for colours from different linguistic categories but only for the right visual field. Our study approached the research question differently. We used the same methodology as Gilbert's team et al. (2006), but we used different colour categories in the Czech language and significantly enlarged the number of participants to 106 undergraduate psychology students. Our results show that the fastest reaction times were in trials when the target was located in the left visual field, quite opposite from the Gilbert's et al. (2006) study. We argue that this finding is based on different processes than simple colour linguistic categorisation and attentional processes actually play an important role in the task.

Does face-selective cortex show a left visual field bias for centrally-viewed faces?

The left half of a centrally-viewed face contributes more strongly to recognition performance than the right. This left visual field (LVF) advantage is typically attributed to an untested assumption that face-selective cortex in the right hemisphere (RH) exhibits a contralateral bias, even for centrally-viewed faces. We tested the validity of this assumption using a behavioral measure of the LVF advantage and an fMRI experiment that measured laterality of face-selective cortex and neural contralateral bias. In the behavioral experiment, participants performed a chimeric face-matching task (Harrison and Strother, 2019). In the fMRI experiment, participants viewed chimeric faces comprised of face halves that either repeated or changed simultaneously in both hemifields, or repeated in one hemifield and changed in the other. This enabled us to measure lateralization of fMRI face-repetition suppression and hemifield-specific half-face sensitivity in face-selective cortex. We found that LVF bias in the fusiform face area (FFA) and right-lateralization of the FFA for changing versus repeated faces were both positively correlated with a behavioral measure of the LVF advantage for upright (but not inverted) faces. Results from regression analyses showed that LVF bias in the right FFA and FFA laterality make separable contributions to the prediction of our behavioral measure of the LVF bias for upright faces. Our results confirm a ubiquitous but previously untested assumption that RH superiority combined with contralateral bias in face-selective cortex explains the LVF advantage in face recognition. Specifically, our results show that neural LVF bias in the right FFA is sufficient to explain the relationship between FFA laterality and the perceptual LVF bias for centrally-viewed faces.

Atypical viewing position effect in developmental dyslexia: A behavioural and modelling investigation

ABSTRACT The probability of recognizing a word depends on the position of fixation during processing. In typical readers, the resulting word-recognition curves are asymmetrical, showing a left-of-centre optimal viewing position (OVP). First, we report behavioural results from dyslexic participants who show atypical word-recognition curves characterized by the OVP being right of centre with recognition probability being higher on the rightmost than on the leftmost letters. Second, we used BRAID, a Bayesian model of word recognition that implements gaze position, an acuity gradient, lateral interference and a visual attention component, to examine how variations in the deployment of visual attention would affect the OVP curves. We show that the atypical dyslexic curves are well simulated assuming a narrow distribution of visual attention and a shifting of visual attention towards the left visual field. These behavioural and modelling findings are discussed in light of current theories of visual attention deficits in developmental dyslexia.

Visual Field Test With Gaze Check Tasks: Application in a Homonymous Hemianopic Patient Unaware of the Visual Defects.

Gaze control is required for applying visual stimuli to a particular area of the visual field. We developed a visual field test with gaze check tasks to investigate hemianopia. In this test, participants must report the presence or absence of visual stimuli when a small object at the fixation point vibrates. Trials in the absence of visual stimuli were used as gaze check tasks, since the vibration could be observed only when the gaze was directed at the fixation point. We evaluated the efficacy of our test in four control participants and one patient with homonymous hemianopia who was unaware of the defects in the left visual field. This patient presented hemianopia in the test with gaze check tasks, but not when the gaze check tasks were omitted. The patient showed spontaneous gaze movements from the fixation point to the upper left direction, as well as scanning of the left visual field during the test without gaze check tasks. Thus, we concluded that the visual defects in this patient were compensated in daily life by spontaneous eye movements coordinated with visual information processing. The present results show the usefulness of the visual field test with gaze check tasks.

Great-tailed grackles can independently direct their eyes toward different targets.

Many species use eye movements to direct their overt attention toward specific targets within their environments. Some species can move each eye independently but we have a limited understanding of whether they can simultaneously monitor different targets with each eye. This study, therefore, tested whether a songbird can independently move its eyes towards two different targets. Captive great-tailed grackles (Quiscalus mexicanus) were simultaneously presented with one target in their left visual field and another target in their right visual field; the targets were both in the upper visual fields, both in the lower visual fields, or one target was in the upper visual field of one eye, while the other target was in the lower visual field of the other eye. The grackles correctly directed their left and right eyes toward the targets regardless of where the targets appeared at levels greater than chance. These results demonstrate that an avian species can perform simultaneous eye movements towards two different targets.

A Case of Relapse of Lymphocytic Hypophysitis Triggered by the Pregnancy of the Second Child

Lymphocytic hypophysitis is a rare immune-mediated inflammatory disorder that causes pituitary dysfunction. It has been reported that lymphocytic hypophysitis onset during pregnancy rarely relapses or exacerbates in subsequent pregnancies. We herein report a patient with relapse of lymphocytic hypophysitis triggered by the pregnancy of the second child. Case Presentation: At the age of 34, at 28 weeks of gestation of the first child, she became aware of left visual field disorder and was diagnosed as an upper left visual field defect. An MRI scan revealed an enlargement of the pituitary gland and the thickening of the stalk. She was referred to our hospital for diagnosis and treatment. Laboratory data showed central adrenocortical dysfunction and central hypothyroidism. Based on the course of the disease, MRI findings and laboratory data, we diagnosed her as lymphocytic hypophysitis occurred during pregnancy. With a replacement dose of hydrocortisone and levothyroxine, she gave birth by cesarean section at 38 weeks of gestation. We performed detailed assessment of anterior pituitary functions with hypothalamic hormone challenges after giving birth. It showed panhypopituitarism without diabetes insipidus. An MRI scan found the compression of the optic chiasm remained after childbirth, the patient underwent steroid pulse therapy. After that, visual field defect improved rapidly, and the patient continued to receive oral prednisolone with gradually reduced amount. An MRI scan performed over time and found the pituitary swelling gradually improved. The pituitary was completely intact 3 years after the onset of disease. At the age of 38, the patient became pregnant with her second child, showed no signs of hypopituitarism at the time of pregnancy. She still had been administrated with 3.5mg/day prednisolone. At the 21 weeks of pregnancy, she became aware of blurred vision and was diagnosed as a left paracenter scotoma. Laboratory data showed a decrease in blood glucose and neutrophil count, suggesting the occurrence of central adrenocortical insufficiency. Therefore, we suspected the relapse of hypophysitis due to second pregnancy. We started hydrocortisone supplementation in addition to prednisolone. No MRI scan was performed during pregnancy, since no progression of visual impairment was observed. She gave birth at 37 weeks of gestation, and postpartum MRI scan showed mild thickening of the stalk. Steroid pulse therapy was not performed because the visual field abnormality was spontaneously improved. Lymphocytic hypophysitis has a diverse course, and there is currently no confirmed risk factor for recurrence. In this case, hypophysitis recurred due to pregnancy despite the continuation of prednisolone administration, and the pathogenic mechanism may be different from the previously reported cases of recurrence of hypophysitis.

Hypopituitarism as the Initial Presentation of Pituitary Metastasis From Lung Cancer

Introduction: The annual incidence of hypopituitarism 4.2 cases of 100,000. Causes include primary tumor, metastasis, and non-tumor causes such as radiation therapy, infiltrative lesions, infection, and traumatic brain injury. Metastatic pituitary tumors constitute about 7-9% of the cases, with lung and breast cancers are the most common primary tumors. Case Presentation: 48-year-old Caucasian female patient with 30 pack-year smoking history presented to the emergency department with abdominal pain, diarrhea, fatigue, and headache. Review of systems was significant for loss of appetite, left eye visual field defect, anorexia, cold intolerance, and shortness of breath. Physical examination was remarkable for decreased visual acuity. Vital signs notable for hypotension BP 92/63. Notable labs include glucose of 53 mg/dL, TSH 0.50 [0.49 - 4.67 uIU/mL], low free T4 0.52 ng/dL, low FSH 1.3 mIU/ml, low LH <0.2 mIU/ml, low ACTH 1.4 pg/mL, low morning cortisol 2.2 ug/dL, low DHEA-SO4 3ug/dL, low IGF-1 16 ng/ml. She was diagnosed with hypopituitarism and started on IV hydrocortisone 50 mg every 6 hours with 75 mcg levothyroxine daily. MRI brain showed interval growth of pituitary lesion into the suprasellar cistern with a mass-effect on the optic chiasm measuring 2.4 X1.6X 1.9 cm with a lesion in the right cerebellar hemisphere. Vertebral MRI showed multiple metastatic lesions in cervical/thoracic/lumbar vertebral bodies. On day two of hospital stay, she developed hypertonic hyponatremia (sodium 156 mmol/L, urine osmolarity 81 mOsm/kg, plasma osmolarity 328 mOsm/kg), and she was started on desmopressin 2 mg IV for diabetes insipidus. CT chest showed spiculated left upper lobe mass consistent with primary malignancy, and biopsy showed metastatic poorly differentiated epithelial malignancy likely from lung primary. Patient was discharged on desmopressin 100 mcg nightly, hydrocortisone 20 mg morning with 10 mg evening, levothyroxine 100 mcg daily with plans for further oncologic workup. Discussion: Patient’s 2011 MRI brain showed a mildly enlarged pituitary gland. MRI brain two months before admission showed a pituitary gland diameter of 1.6 cm, while an MRI at presentation showed a pituitarygland size of 2.4 cm with a new cerebellar lesion. She reported symptoms of nausea, vomiting, and weakness for more than one year ago but biochemical testing was not performed. The fact that the patient had pituitary enlargement eight years ago likely delayed the diagnosis of pituitary metastasis. Patient age precluded lung cancer screening despite smoking history and family history of lung cancer. Conclusion: Symptomatic patients with pituitary enlargement on brain imaging may benefit from a close follow-up and biochemical testing for early diagnosis and treatment, especially if they have risk factors for malignancy.

New Treatment Options for Pituitary Granulomatosis With Polyangiitis

Background: Granulomatosis with polyangiitis (GPA) rarely involves the pituitary gland and has been reported in 1% of all cases of GPA. Most frequently, it presents with pituitary mass effect and diabetes insipidus (DI). To date, there are no treatment guidelines for this rare condition. Case Presentation: Case 1: A 55 year old female with a history of ANCA-positive pulmonary GPA, previously treated with glucocorticoids and immunosuppressants, presented two years later with cranial DI and bitemporal hemianopia. MRI showed a large sellar mass with suprasellar extension. High dose glucocorticoids resulted in good clinical and radiological response. Further treatment consisted in a combination of Cyclophosphamide and Rituximab (RTX). Further doses of RTX are planned aiming for a period of B-cell depletion. Case 2: A 38 year old female, presented with polyuria, recurrent nosebleeds, headaches and a left visual field defect. Pituitary profile revealed ACTH deficiency and MRI showed a heterogenous cystic lesion with peripheral enhancement and stalk thickening. Steroid replacement led to immediate improvement in her symptoms. Cranial DI was confirmed and raised Proteinase 3 (PR3) antibody suggested GPA. A combination of prednisolone and Methotrexate led to significant improvement of MRI appearances and declining PR3 antibody levels. For remission maintenance, two cycles of RTX were given with further radiological and biochemical improvement, and, following dynamic assessment of her HPA axis, she could be fully weaned off steroids. Case 3 is a 47 year old female with a history of childhood asthma. She was found to have cavitating lung lesions. ANCA positivity confirmed GPA and she was commenced on high-dose steroids. During follow-up, she developed headache, polyuria and polydipsia. MRI pituitary showed a suprasellar lesion and pituitary biopsy revealed inflammatory hypophysitis. Cranial DI was confirmed by water deprivation testing. Previous allergic reactions to both RTX and Ofatumumab precluded anti-CD40 monoclonal antibodies and she was commenced on Azathioprine. A further recurrence of pituitary GPA necessitated escalation of the steroid dose and switch of azathioprine to mycophenolate mofetil. She remains in remission and her steroids reduced to a maintenance dose. Conclusion: GPA pituitary has been observed to occur at variable time after diagnosis often in the absence of any other systemic features. A combination of glucocorticoids and RTX has been approved for severe relapsing pulmonary GPA, however, limited data is available for pituitary GPA. In this case series, the response to high dose steroids and RTX for remission maintenance has been encouraging. Experience with ‘conventional’ immunosuppresants remains limited and therapeutic responses remain variable. Further clinical studies are required to establish effective treatment for pituitary GPA.

The role of orthographic neighbourhood effects in lateralized lexical decision: a replication study and meta-analysis.

The effect of orthographic neighbourhood size (N) on lexical decision reaction time differs when words are presented in the left or right visual fields. Evidence suggests a facilitatory N effect (i.e., faster reaction times for words with larger neighbourhoods) in the left visual field. However, the N effect in the right visual field remains controversial: it may have a weaker facilitative role or it may even be inhibitory. In a pre-registered online experiment, we replicated the interaction between N and visual field and provided support for an inhibitory N effect in the right visual field. We subsequently conducted a pre-registered systematic review and meta-analysis to synthesise the available evidence and determine the direction of N effects across visual fields. Based on the evidence, it would seem the effect is inhibitory in the right visual field. Furthermore, the size of the N effect is considerably smaller in the right visual field. Both studies revealed considerable heterogeneity between participants and studies, and we consider the implications of this for future work.

Do Students Respond Faster to Inequalities with a Greater than Sign or to Inequalities with a Less than Sign: Spatial-Numerical Association in Inequalities

ABSTRACT Previous studies have suggested that there is a left-to-right mental number line, which is based on individuals responding faster when a smaller magnitude is presented on the left visual field and a larger magnitude is presented on the right visual field. This study examined whether the Spatial-Numerical Associations could influence individuals’ responses in an inequality judgment task. Specifically, this study tested the differences in reaction time between judging inequalities with a greater than sign and inequalities with a less than sign and investigated individuals’ subjective liking and perceived fluency in judging these inequalities. Three types of stimuli were used in this study: Arabic number inequalities (numerical and symbolic magnitudes), dot array inequalities (numerical and non-symbolic magnitudes), and square inequalities (non-numerical magnitudes). Results showed that participants reacted quicker to inequalities with a greater than sign than a less than sign when responding to true inequalities in all of the three tasks and reported more subjective liking and perceived fluency in judging inequalities with a greater than sign in symbolic task. This study has implications for studies that are interested in Spatial-Numerical Associations and mathematical education.

Using fast visual rhythmic stimulation to control inter-hemispheric phase offsets in visual areas

Spike timing dependent plasticity (STDP) is believed to be important for neural communication and plasticity in human episodic memory, but causal evidence is lacking due to technical challenges. Rhythmic sensory stimulation that has been used to investigate causal relations between oscillations and cognition may be able to address this question. The challenge, however, is that the frequency corresponding to the critical time window for STDP is gamma (~40 Hz), yet the application of rhythmic sensory stimulation has been limited primarily to lower frequencies (<30 Hz). It remains unknown whether this method can be applied to precisely control the activation time delay between distant groups of neurons at a millisecond scale. To answer this question and examine the role of STDP in human episodic memory, we simulated the STDP function by controlling the activation time delay between the left and right visual cortices during memory encoding. This was achieved by presenting flickering (37.5 Hz) movie pairs in the left and right visual fields with a phase lag of either 0, 90, 180 or 270°. Participants were asked to memorize the two movies within each pair and the association was later tested. Behavioral results revealed no significant difference in memory performance across conditions with different degrees of gamma phase synchrony. Yet importantly, our study showed for the first time, that oscillatory activity can be driven with a precision of 6.67 ms delay between neuronal groups. Our method hereby provides an approach to investigate relations between precise neuronal timing and cognitive functions.

Fast saccades towards faces are robust to orientation inversion and contrast negation

Eye movement studies show that humans can make very fast saccades towards faces in natural scenes, but the visual mechanisms behind this process remain unclear. Here we investigate whether fast saccades towards faces rely on mechanisms that are sensitive to the orientation or contrast of the face image. We present participants pairs of images each containing a face and a car in the left and right visual field or the reverse, and we ask them to saccade to faces or cars as targets in different blocks. We assign participants to one of three image conditions: normal images, orientation-inverted images, or contrast-negated images. We report three main results that hold regardless of image conditions. First, reliable saccades towards faces are fast – they can occur at 120–130 ms. Second, fast saccades towards faces are selective – they are more accurate and faster by about 60–70 ms than saccades towards cars. Third, saccades towards faces are reflexive – early saccades in the interval of 120–160 ms tend to go to faces, even when cars are the target. These findings suggest that the speed, selectivity, and reflexivity of saccades towards faces do not depend on the orientation or contrast of the face image. Our results accord with studies suggesting that fast saccades towards faces are mainly driven by low-level image properties, such as amplitude spectrum and spatial frequency.

Unilateral cortical FLAIR-hyperintense Lesion in Anti-MOG-associated Encephalitis with Seizures (FLAMES) on TNF inhibitor therapy

A 34-year-old man presented with new-onset right-sided headache, episodic visuospatial disorientation and episodic photopsia in his left visual field. His medical history was significant for ulcerative colitis, well-controlled on infliximab...

How Much Do Clinical and Microperimetric Findings Affect Reading Speed in Low Vision Patients with Age-related Macular Degeneration?

ABSTRACT Purpose: To investigate the factors affecting the reading speed of patients with central scotoma due to age-related macular degeneration (AMD). Materials and Methods: We included 63 eyes of 63 patients with AMD who applied to our low vision clinic between August 2018 and September 2019 in this prospective study. We evaluated socio-demographic characteristics, eye examination findings and Minnesota Low Vision Reading Test (MNREAD) results. We used the MAIA microperimeter device to evaluate the properties of the preferred retinal locus for fixation (PRL) of the patients. Evaluations included the assessment of the effects of all parameters on reading speed. Results: The PRL was most commonly in the nasal (31%) and superior (26%) quadrants. Twenty-nine percent of the cases preferred the left visual field. PRL localization had no effect on reading speed, whereas, fixation stability, educational status, presence of foveal absolute scotoma, reading acuity and duration of reading interruption were found to have the most significant effects. Multiple regression analysis showed that reading speed decreased by 67 units in the presence of unstable fixation, by 17 units in the presence of foveal absolute scotoma, by 3 units with every 0.1 increase in logMAR value, and by 1.7 units with every 1-year increase in reading interruption. Additionally, being a university graduate was associated with an increased reading speed (by 18 units) Conclusion: Increased reading performance is one of the factors that can improve quality of life. The factors found to affect the reading speed in the current study may guide the rehabilitation process in low vision patients.

Location and stability of the preferred retinal locus in native Persian‐speaking patients with age‐related macular degeneration

ABSTRACT Clinical relevance The findings of this study can be used in the selection of the preferred retinal locus to establish better rehabilitation services such as eccentric viewing training for patients with age‐related macular degeneration. Background The aim of this study was to determine the characteristics of the preferred retinal locus in native Persian‐speaking patients with age‐related macular degeneration. Methods In this non‐interventional case series, all patients with a diagnosis of age‐related macular degeneration referred to the Retina Clinic of the Rassoul Akram Hospital, Tehran, Iran, were evaluated. The fixation characteristics were evaluated monocularly using the MP1 microperimeter (Nidek Technologies, Padua, Italy). Optical coherence tomography was used to determine the location of the central fovea. The images were overlaid and the preferred retinal locus‐fovea distance was measured using Image J software. Results Fifty‐one eyes of 35 patients with a mean age of 73.8 ± 7.7-years were evaluated in this study. Inferior‐field, left‐field, central‐field, right‐field, and superior‐field preferred retinal locus were detected in 49 per cent, 33.3 per cent, 7.8 per cent, 5.9 per cent, and 3.9 per cent of the subjects, respectively. Fixation was stable in 70.6 per cent, relatively unstable in 15.7 per cent, and unstable in 13.7 per cent of the participants. Significant differences were not found in the mean values of logMAR visual acuity between different fields of the preferred retinal locus after Bonferroni correction (p = 0.031). Analysis of co‐variance showed no significant difference in mean sensitivity values between different locations of the preferred retinal locus (p = 0.07). The mean preferred retinal locus‐fovea distance was not significantly different between different fields of the preferred retinal locus (p = 0.063). Conclusions Native Persian‐speaking patients with central scotoma secondary to age‐related macular degeneration place their self‐selected preferred retinal locus most frequently in the inferior and left visual field, which would result in scotoma displacement to the superior and right visual field. Fixation stability was statistically similar in different locations of preferred retinal locus, but it improved with decreasing the preferred retinal locus‐fovea distance.

Single-Case Neuropsychological Assessment of a Patient with a Posterior Parietal Lesion Using Behavioral Testing and Resting-State fMRI

This study integrated functional connectivity measures using resting-state fMRI and behavioral data from a single-case observation of patient (PER) one year after right-hemispheric hemorrhage in the intraparietal sulcus and superior parietal lobule (IPS/SPL). PER showed no sign of clinical neglect. Her behavioral performance in the visuo-manual pointing task and in the letter discrimination task under conditions of endogenous and exogenous attentional cueing was compared between the left (affected) and right (unaffected/control) peripheral visual fields. The resting-state fMRI demonstrated an imbalance between the right and left hemispheric frontoparietal functional connectivity within the dorsal attentional and motor networks. Although the frontal and occipital cortices were not structurally damaged, specific fronto-occipital functional connectivity was imbalanced, which was strongly associated with the behavioral changes. First, the activity in the right frontal eye field showed weaker correlations with the activity in the right inferior occipital area compared to the correlation with the activity in the left inferior occipital area. This imbalanced fronto-occipital functional connectivity was accompanied by a specific impairment in endogenous covert attention in the left visual field. Second, the activity within M1 in both hemispheres showed weaker correlations with the activity of the right cuneus compared to the correlation with the activity in the left cuneus. The imbalanced fronto-occipital functional connectivity was associated with the impairment of the reaching movement of the left and right hands towards the left visual field (optic ataxia). Altogether, our results showed that a lesion to the posterior parietal cortex affects the relationship between distal regions underlying the sensorimotor and attentional abilities