Glaucoma-associated abnormalities in cortical activity during a visuocognitive task.

OBJECTIVE: To investigate neurophysiological dynamics during a visuocognitive task in glaucoma patients vs. healthy controls. METHODS: Fifteen patients with early-stage primary open-angle glaucoma (POAG) and fifteen age-matched healthy participants underwent a "go/no-go" task, monitored with EEG. Participants had to semantically categorize visual objects in central vision, with animal or furniture as targets according to the experimental block. RESULTS: Early visual processing was delayed by 50 ms in patients with POAG compared to controls. The patients displayed a smaller difference between animal and furniture categorization during higher-level cognitive processing (at 400-600 ms). Regarding behavioral data, the groups differed in accuracy performance and decision criterion. As opposed to the control group, patients did not display facilitation and a higher accuracy rate for animal stimuli. However, patients maintained a consistent decision criterion throughout the experiment, whereas controls displayed a shift towards worse decision criteria in furniture trials, with higher error rate. CONCLUSIONS: The comparative analysis of behavioral and neurophysiological data revealed in POAG patients a delay in early visual processing, and potential high-level cognitive compensation during late, task-dependent activations. SIGNIFICANCE: To our knowledge, our findings provide the first evidence of modification in cognitive brain dynamics associated with POAG.

Central Visual Attention in Primary Open-angle Glaucoma.

SIGNIFICANCE: To better understand the implication of a potential cognitive change in glaucoma, patients were stimulated in central visual areas considered functionally normal to discard an effect due to the loss of vision during an attentional task. The outcome might improve the follow-up on the impact of the pathology. PURPOSE: This study aimed to evaluate the effect of primary open-angle glaucoma on the visual attention system by recording responses of behavioral and oculomotor strategies. METHODS: We included 20 individuals with primary open-angle glaucoma (62.1 ± 7.2 years old), 18 age-matched control subjects (58.4 ± 7.2 years old), and 20 young control subjects (25.7 ± 3.5 years old). The procedure consisted of visual (eye-tracking recordings) and manual detection of a target. All participants had to detect a square with a vertical bar within distractors (squares, triangles, and circles with a horizontal or vertical bar) of identical size of 1.6 × 1.6° visual angle. The shapes were displayed concentrically on a radius of 5° of visual angle. All participants were tested to ensure that their visual field sensitivity was normal within ±5° central vision. RESULTS: In responding manually, glaucoma participants were slower than age-matched control subjects (1723 ± 488 vs. 1263 ± 385 milliseconds; P < .01). Eye-tracking recordings showed that glaucoma participants found the target within the same time frame as age-matched control subjects. Compared with the young group, the scanpath length and average fixation duration on distractors were significantly longer for the glaucoma patients (+235 pixels, +104 milliseconds) and the age-matched control participants (+120 pixels, +39 milliseconds). Impaired contrast sensitivity was correlated with longer response time, longer scanpath, and longer fixation on distractors. CONCLUSIONS: Glaucoma affects the manual response times in a visual attention task, but patients can visually detect the target as quickly as age-matched control subjects. Different clinical factors predicted the performances. The age of the patients was associated with longer scanpath. The visual field loss (mean deviation) was linked with longer visual response time. The loss of contrast sensitivity predicted the behavioral change on fixation duration to the distractors, global response time, visual response time, and scanpath length.

How Do Women and Men Look at the Past? Large Scanpath in Women during Autobiographical Retrieval-A Preliminary Study.

While research has consistently demonstrated how autobiographical memory triggers visual exploration, prior studies did not investigate gender differences in this domain. We thus compared eye movement between women and men while performing an autobiographical retrieval task. We invited 35 women and 35 men to retrieve autobiographical memories while their gaze was monitored by an eye tracker. We further investigated gender differences in eye movement and autobiographical specificity, that is, the ability to retrieve detailed memories. The analysis demonstrated shorter fixations, larger duration and amplitude of saccades, and higher autobiographical specificity in women than in men. The significant gender differences in eye movement disappeared after controlling for autobiographical specificity. When retrieving autobiographical memory, female participants generated a large scan with short fixation and high saccade amplitude, while male participants increased their fixation duration and showed poorer gaze scan. The large saccades in women during autobiographical retrieval may constitute an exploratory gaze behavior enabling better autobiographical memory functioning, which is reflected by the larger number of autobiographical details retrieved compared to men.

Dynamics of low-pass-filtered object categories: A decoding approach to ERP recordings.

Rapid analysis of low spatial frequencies (LSFs) in the brain conveys the global shape of the object and allows for rapid expectations about the visual input. Evidence has suggested that LSF processing differs as a function of the semantic category to identify. The present study sought to specify the neural dynamics of the LSF contribution to the rapid object representation of living versus non-living objects. In this EEG experiment, participants had to categorize an object displayed at different spatial frequencies (LSF or non-filtered). Behavioral results showed an advantage for living versus non-living objects and a decrease in performance with LSF pictures of pieces of furniture only. Moreover, despite a difference in classification performance between LSF and non-filtered pictures for living items, the behavioral performance was maintained, which suggests that classification under our specific condition can be based on LSF information, in particular for living items.

Reduced peripheral vision in glaucoma and boundary extension.

CLINICAL RELEVANCE: Peripheral vision is known to be critical for spatial navigation. However, visual cognition, which impacts peripheral vision, has not been studied extensively in glaucoma. BACKGROUND: Spatial memory was assessed with a known to induce a robust memory distortion called "boundary extension" in which participants erroneously remember seeing more of a scene than was present in the sensory input. METHODS: Fifteen patients with glaucoma and 15 age-matched normally sighted controls participated in the experiment. Participants were shown 10 photographs of natural scenes randomly displayed for 0.5 s or 10 s. Following each scene, the participant was asked to draw it from memory. RESULTS: On average, boundary extension was larger, by 12%, for patients than for controls, but the difference was significant for 4 photographs. Patients tended to add more space between the object and the edges than there was between the objects and the border of the photograph. A control experiment in which participants were asked to draw isolated objects without scene context resulted in a significant reduction of the memory distortion in both groups, but patients still drew the objects smaller than controls. CONCLUSION: The reduced field of view in glaucoma has an impact on spatial memory for scenes and on perception of size.

The pupil and myself: pupil dilation during retrieval of self-defining memories.

BACKGROUND: There is a recent interest in pupil dilation during the retrieval of autobiographical memory. We pursued this line of research by measuring pupil diameter during the retrieval of self-defining memories, that is, memories that are highly vivid, emotionally intense, and are retrieved to reflect enduring concerns in a person's life. METHODS: We invited 40 participants to retrieve self-defining memories while their pupil activity was recorder with eye-tracking glasses. We analyzed memories regarding specificity (i.e., specific or general) and emotional valence (neutral, positive, negative, or mixed). RESULTS: Analysis demonstrated larger pupil diameter during the retrieval of specific than general self-defining memories. However, no significant differences in pupil diameter were observed across the four emotional categories of self-defining memories. DISCUSSION: The increased pupil size during retrieval of specific self-defining memories can be attributed to the autonoetic experience during retrieval of these memories and/or to the cognitive load as required to construct these memoires. By investigating pupil dilation during the retrieval of self-defining memories, our study provides an original, ecological, and reliable physiological assessment of these memories.

The eyes of the past: larger pupil size for autobiographical memories retrieved from field perspective.

BACKGROUND: Visual perspective during memory retrieval has mainly been evaluated with methodologies based on introspection and subjective reports. The current study investigates whether visual perspective can be evaluated with a physiological measurement: pupil dilation. METHODS: While their pupil diameter was measured with an eye-tracker, forty-five participants retrieved one memory from a field perspective (i.e., as viewed through our own eyes) and one memory from an observer perspective (i.e., as viewed from a spectator's standpoint). After retrieval, participants rated the emotional intensity of the memories. RESULTS: Analysis demonstrated larger pupils during the retrieval of memories from a field perspective and higher emotional intensity for memories retrieved from a field perspective. DISCUSSION: The larger pupils for memories recalled from a field perspective could, however, not be attributed to their higher emotional intensity. These findings suggest that pupil dilation could be used as a physiological assessment of visual perspective during memory retrieval.

Glaucoma and Computer Use: Do Contrast and Color Enhancements Improve Visual Comfort in Patients?

PURPOSE: To estimate the impact of glaucoma on computer use and to assess specific adaptations of the graphical interface to this form of visual impairment. DESIGN: Prospective, experimental cohort study. PARTICIPANTS: Forty-nine participants were recruited: 16 patients with primary open-angle glaucoma (mean ± SD, 62.7 ± 5.6 years of age), 17 age-matched participants (mean ± SD, 59.1 ± 8.3 years of age), and 16 young control participants (mean ± SD, 23.3 ± 2.1 years of age). METHODS: An ophthalmologic examination before the study evaluated the level of visual loss (mean deviation), visual acuity (logarithm of the minimum angle of resolution units), and contrast sensitivity (CS) of the primary open-angle glaucoma patients. Each participant underwent the following measurements: an information technology (IT) experience questionnaire, a preference task monitored by eye tracking, and a feedback session. The experimental task was based on ecological computer scenes with 3 enhancement levels (low, medium, and high), determined by gradual modulation of contrast, luminance, and color. Participants were asked to select the most readable and comfortable stimulus among 4 images displayed on the screen: the original computer scene and 3 enhanced versions. MAIN OUTCOME MEASURES: Clinical, oculomotor, and subjective data were computed together in a multivariate model by using a principal component analysis (PCA). RESULTS: The PCA revealed 3 principal components accounting for 72% of the total variance of the data and showed a greater need for enhanced computer scenes in glaucoma patients, an equal preference for low and medium enhancement within the 3 groups, and significantly longer oculomotor behavior in the patient groups. Subjective reports of difficulty using IT because of vision were correlated with visual impairment and high enhancement preference. Contrast sensitivity was critical to explaining the main variations of the data. A reduced CS had a significant effect on the preference for enhanced computer scenes (r = -0.43; P < 0.002) and a less effective exploration velocity (r = 0.43; P < 0.002). CONCLUSIONS: Glaucoma alters the global exploration of computer scenes. High enhancement of the graphical interface could improve visual comfort during computer use. Subjective patients' reports underline the importance of including IT questions in visual-related quality-of-life questionnaires.

Magnocellular and Parvocellular Mediated Luminance Contrast Discrimination in Severe Alcohol Use Disorder.

BACKGROUND: Severe alcohol use disorder (SAUD) is associated with widespread cognitive impairments, including low-level visual processing deficits that persist after prolonged abstinence. However, the extent and characteristics of these visual deficits remain largely undetermined, impeding the identification of their underlying mechanisms and influence on higher-order processing. In particular, little work has been conducted to assess the integrity of the magnocellular (MC) and parvocellular (PC) visual pathways, namely the 2 main visual streams that convey information from the retina up to striate, extrastriate, and dorsal/ventral cerebral regions. METHODS: We investigated achromatic luminance contrast processing mediated by inferred MC and PC pathways in 33 patients with SAUD and 32 matched healthy controls using 2 psychophysical pedestal contrast discrimination tasks that promote responses of inferred MC or PC pathways. We relied on a staircase procedure to assess participants' ability to detect small changes in luminance within an array of 4 gray squares that were either continuously presented (steady pedestal, MC-biased) or briefly flashed (pulsed pedestal, PC-biased). RESULTS: We replicated the expected pattern of MC and PC contrast responses in healthy controls. We found preserved dissociation of MC and PC contrast signatures in SAUD but higher MC-mediated mean contrast discrimination thresholds combined with a steeper PC-mediated contrast discrimination slope compared with healthy controls. CONCLUSION: These findings indicate altered MC-mediated contrast sensitivity and PC-mediated contrast gain, confirming the presence of early sensory disturbances in individuals with SAUD. Such low-level deficits, while usually overlooked, might influence higher-order abilities (e.g., memory, executive functions) in SAUD by disturbing the "coarse-to-fine" tuning of the visual system, which relies on the distinct functional properties of MC and PC pathways and ensures proper and efficient monitoring of the environment.

What is the Nature of the Reach-and-Grasp Deficit in Glaucoma?

PRéCIS:: In a reach-and-grasp task, patients with glaucoma exhibited a motor disorder, even when they had time to explore their environment. The motor performance of glaucoma patients should be taken into account in rehabilitation. PURPOSE: Vision plays an important role in planning and executing manual prehension (reaching and grasping). We assess the impact of glaucoma on motor production, as a function of the visual exploration time available to the patients. METHODS: We compared performance in 2 reach-and-grasp tasks determined by whether or not the participants (16 glaucoma patients, 14 age-matched and 18 young controls) had time to explore the objects before reaching and grasping a target object defined by its color. RESULTS: Differences were observed between glaucoma patients and age-matched controls on movement duration and peak velocity (reaching phase) only when participants were not provided time to look at the objects before the movement (immediate condition). CONCLUSIONS: Glaucoma patients exhibited a motor disorder (grasping phase) only when they had no time to explore their environment before performing the reach-and-grasp task. The motor abnormalities in reaching phase observed in glaucoma patients in previous studies seem to result from difficulties in target identification rather than from visuomotor deficits. From a clinical point of view, motor performances of glaucoma patients could be modulated by task, especially by temporal constraints of task.

Context Association in Glaucoma Patients Using a Touch Screen.

PRECIS: The results showed that people with glaucoma are able to perform with high accuracy a context-association task on a touch screen. This device could be a new possibility for communication and for clinical assessment. BACKGROUND: The present study was designed to investigate the ability of patients with glaucoma to use a touch screen to find and associate pictures with limited text. METHODS: Eighty-four volunteers were recruited in 3 groups and tested binocularly or monocularly. Twenty-eight patients with binocular glaucoma (M=68.5 y) were selected with a visual acuity of 0.4 log MAR or better in each eye and visual field defects, with a mean deviation equal to or less than -6 dB in each eye. Twenty-eight age-matched controls (M=68.8 y) and 28 young controls (M=22.1 y) were also recruited (normal acuity; exclusion of ocular disease). The participants had to associate, by moving their index on a 22″ touch screen, a target on the unique scene (between 3 other distractor images) with a consistent background related to the target (eg, to match a fish with the sea). RESULTS: The performances of the glaucomatous patients were significantly (P<0.01) impaired in monocular vision compared with binocular vision with regard to the exploration duration (+2 s), accuracy (-3% of correct response), and peak speed (-10 cm/s). However, with binocular vision, representing daily life conditions, exploration duration, deviation, movement duration, peak speed, and accuracy were not affected by glaucoma, as demonstrated by comparison with the age-matched group. CONCLUSIONS: People with glaucoma are able to perform with high accuracy a context-association task on a touch screen. Many applications involving touch screen devices should provide new tools with limited text to help patients with visual disabilities.

Autobiographical Memory Increases Pupil Dilation.

BACKGROUND: Pupil activity has been widely considered as a "summed index" of physiological activities during cognitive processing. METHODOLOGY: We investigated pupil dilation during retrieval of autobiographical memory and compared pupil diameter with a control condition in which participants had to count aloud. We also measured pupil diameters retrieval of free (i.e., first memory that comes to mind), positive, and negative memories (memories associated, respectively, with the words "happy" and "sad"). RESULTS: Analyses demonstrated larger pupil diameters during the free, positive, and negative autobiographical memory retrieval than during the control task. Analyses also demonstrated no significant differences in pupil diameters across the three autobiographical memory conditions. CONCLUSION: These outcomes demonstrate that, compared with counting, autobiographical retrieval results in a larger pupil size. However, the emotional valence of memories yields non-significant effect on pupil diameters. Our findings demonstrate how autobiographical memory retrieval yields pupil dilation.

Don't stare, unless you don't want to remember: Maintaining fixation compromises autobiographical memory retrieval.

This study has developed an original approach to the relationship between eye movements and autobiographical memory, by investigating how maintained fixation could influence the characteristics of retrieved memories. We invited participants to retrieve autobiographical memories in two conditions: while fixating a cross at the centre of a screen and while freely exploring the screen. Memories retrieved during the maintained fixation condition were less detailed and contained less visual imagery than those retrieved during the free-gaze condition. Memories retrieved during the maintained fixation condition were retrieved slower and took less time to describe than those retrieved during the free-gaze condition. As for the characteristics of eye movements, analysis showed fewer and longer fixations as well as fewer saccades in the maintained fixation than in the free-gaze condition. Maintaining fixation is likely to tax cognitive resources that are necessary for the reconstruction of autobiographical memory. Our findings demonstrate how maintained fixation may result in a more effortful construction of autobiographical memory and memories with lower spatiotemporal specificity and poorer mental images.

Attentional capture by incongruent object/background scenes in patients with Alzheimer disease.

AIM: Object/background association is critical to understand the context of visual scenes but also in daily life tasks like object search. Patients with Alzheimer disease (AD) exhibit impairment in scene processing at different levels: perception, recognition, memory and spatial navigation. We explored whether patients with AD make use of contextual information in congruent and incongruent target/background conditions in three different saccadic choice tasks. EXPERIMENT: We recruited 36 participants (12 young, 12 patients with AD at a moderate stage and 12 age-matched controls). Pairs of scenes (one congruent and one incongruent object/background) were displayed. In a free viewing task we recorded whether the participants spontaneously direct their gaze (eye tracker recordings) toward the congruent or the incongruent scene. In a task referred as "implicit", the participants had to saccade toward a pre-defined target (animal or piece of furniture) in a scene (congruent or not with the target). In a task, called "explicit", participants had to saccade towards the congruent scene. RESULTS: In contrast with both young and older controls patients with AD showed difficulties to refrain a first saccade toward incongruent scenes in the free viewing and the implicit tasks. They were at chance level in the explicit task. When given time to explore the two scenes, in a manual response condition, they were able to accomplish the implicit and explicit tasks with good accuracy. CONCLUSION: In contrast to healthy controls patients with AD exhibited a strong, significant, bias towards incongruent object/background scenes, even in the free viewing task, suggesting that unfamiliar or deviant stimuli attract their attention spontaneously. This result is in line with studies showing impairments in filtering out irrelevant distractors in visual search tasks and with studies suggesting inefficient top-down control to select relevant information at early stage of the disease.

What Is the Nature of the Reach and Grasp Deficit in Wet Age-related Macular Degeneration?

SIGNIFICANCE: Vision is paramount for motor actions directed toward objects. Vision allows not only the identification of objects and their shape and spatial location, but also the adaptation of our movement when it arrives on the object. These findings show that vision deficits, as in age-related macular degeneration (AMD), can lead to reaching and grasping deficits. PURPOSE: Few studies have investigated reaching and grasping in patients with AMD. They showed a deficit in the execution of motor actions in people with AMD, even though these people do not mention difficulties in their daily lives. The purpose of this study was to understand the nature of impairments in motor actions in patients. METHODS: We compared performance in two reach-and-grasp tasks determined by whether the participants (16 people with wet AMD and 17 age-matched control subjects) had time to look at the object before reaching and grasping it. RESULTS: The results show that the kinematic parameters of reach-and-grasp movements do not differ between groups when participants are provided time to look at the object before the movement. In contrast, performance in terms of movement duration, acceleration time, time to reach the maximum grip aperture, and the maximum velocity differ between patients and control subjects when the object is displayed immediately before the movement. CONCLUSIONS: The motor perturbations observed in people with AMD in previous studies seem to result from difficulties in target identification rather than from visuomotor deficits.

Eying the future: Eye movement in past and future thinking.

We investigated eye movement during past and future thinking. Participants were invited to retrieve past events and to imagine future events while their scan path was recorded by an eye-tracker. Past thinking triggered more fixation (p < .05), and saccade counts (p < .05) than future thinking. Past and future thinking triggered a similar duration of fixations and saccades, as well as a similar amplitude of saccades. Interestingly, participants rated past thinking as more vivid than future thinking (p < .01). Therefore, the vividness of past thinking seems to be accompanied by an increased number of fixations and saccades. Fixations and saccades in past thinking can be interpreted as an attempt by the visual system to find (through saccades) and activate (through fixations) stored memory representations. The same interpretation can be applied to future thinking as this ability requires activation of past experiences. However, future thinking triggers fewer fixations and saccades than past thinking: this may be due to its decreased demand on visual imagery, but could also be related to a potentially deleterious effect of eye movements on spatial imagery required for future thinking.

Eye movement during retrieval of emotional autobiographical memories.

This study assessed whether specific eye movement patterns are observed during emotional autobiographical retrieval. Participants were asked to retrieve positive, negative and neutral memories while their scan path was recorded by an eye-tracker. Results showed that positive and negative emotional memories triggered more fixations and saccades but shorter fixation duration than neutral memories. No significant differences were observed between emotional and neutral memories for duration and amplitude of saccades. Positive and negative retrieval triggered similar eye movement (i.e., similar number of fixations and saccades, fixation duration, duration of saccades, and amplitude of saccades). Interestingly, the participants reported higher visual imagery for emotional memories than for neutral memories. The findings demonstrate similarities and differences in eye movement during retrieval of neutral and emotional memories. Eye movement during autobiographical retrieval seems to be triggered by the creation of visual mental images as the latter are indexed by autobiographical reconstruction.

Category-Specific Visual Recognition and Aging from the PACE Theory Perspective: Evidence for a Presemantic Deficit in Aging Object Recognition.

Background/Study Context: The objective of this study was to investigate the object recognition deficit in aging. Age-related declines were examined from the presemantic account of category effects (PACE) theory perspective (Gerlach, 2009, Cognition, 111, 281-301). This view assumes that the structural similarity/dissimilarity inherent in living and nonliving objects, respectively, can account for a wide range of category-specific effects. METHODS: In two experiments on object recognition, young (36 participants, 18-27 years) and older (36 participants, 53-69 years) adult participants' performances were compared. RESULTS: The young adults' results corroborate the PACE theory expectations. The results of the older adults showed an impairment in recognition of structurally similar objects irrespective of semantic category. CONCLUSION: The two sets of results suggest that a deficit in the selection stage of the PACE theory (visual long-term memory matching) could be responsible for these impairments. Indeed, the older group showed a deficit when this stage was most relevant. This article emphasize on the critical need for taking into account structural component of the stimuli and type of tasks in further studies.

Visual object categorisation in people with glaucoma.

PURPOSE: There is evidence that people with glaucoma exhibit difficulties with some complex visual tasks such as face recognition, motion perception and scene exploration. The purpose of this study was to determine whether glaucoma affects the ability to categorise briefly presented visual objects in central vision. METHODS: Visual categorisation performance of 14 people with glaucoma (primary open angle glaucoma and preperimetric) and 15 age-matched controls was measured, assessing both accuracy and response times. Grey level photographs of objects (size) were presented for 28 ms foveally. Perimetric thresholds were normal for all participants within the central 3°. Two levels of contrasts were included: one medium level at 50% and one with high contrast at 100%. RESULTS: On average, accuracy was significantly decreased by 7% (p=0.046) for the medium contrast stimuli in patients with glaucoma (87% of correct response, SD: 5%) compared with controls (94% of correct response, SD: 4.7%). Group average response times were significantly slower for the patients relative to the control group (712 ms, SD: 53 ms compared with 643 ms, SD: 34 ms for the control group; p<0.01). Performance was equivalent in the two groups when the picture contrast was 100%. CONCLUSIONS: The impairment observed in the categorisation task supports previous work that demonstrates that people with glaucoma can have greater difficulties with complex visual tasks than is predicted by their visual field loss. The performance was equivalent to age-matched controls when contrast was maximised.

Finding faces, animals, and vehicles in far peripheral vision.

Neuroimaging studies have shown that faces exhibit a central visual field bias, as compared to buildings and scenes. With a saccadic choice task, Crouzet, Kirchner, and Thorpe (2010) demonstrated a speed advantage for the detection of faces with stimuli located 8° from fixation. We used the same paradigm to examine whether the face advantage, relative to other categories (animals and vehicles), extends across the whole visual field (from 10° to 80° eccentricity) or whether it is limited to the central visual field. Pairs of photographs of natural scenes (a target and a distractor) were displayed simultaneously left and right of central fixation for 1s on a panoramic screen. Participants were asked to saccade to a target stimulus (faces, animals, or vehicles). The distractors were images corresponding to the two other categories. Eye movements were recorded with a head-mounted eye tracker. Only the first saccade was measured. Experiment 1 showed that (a) in terms of speed of categorization, faces maintain their advantage over animals and vehicles across the whole visual field, up to 80° and (b) even in crowded conditions (an object embedded in a scene), performance was above chance for the three categories of stimuli at 80° eccentricity. Experiment 2 showed that, when compared to another category with a high degree of within category structural similarity (cars), faces keep their advantage at all eccentricities. These results suggest that the bias for faces is not limited to the central visual field, at least in a categorization task.