Case report: "Proust phenomenon" after right posterior cerebral artery occlusion.

Odors evoking vivid and intensely felt autobiographical memories are known as the "Proust phenomenon," delineating the particularity of olfaction in being more effective with eliciting emotional memories than other sensory modalities. The phenomenon has been described extensively in healthy participants as well as in patients during pre-epilepsy surgery evaluation after focal stimulation of the amygdalae and post-traumatic stress disorder (PTSD). In this study, we provide the inaugural description of aversive odor-evoked autobiographical memories after stroke in the right hippocampal, parahippocampal, and thalamic nuclei. As potential underlying neural signatures of the phenomenon, we discuss the disinhibition of limbic circuits and impaired communication between the major networks, such as saliency, central executive, and default mode network.

Clinical Evaluation of a Quantitative Imaging Biomarker Supporting Radiological Assessment of Hippocampal Sclerosis.

OBJECTIVE: To evaluate the influence of quantitative reports (QReports) on the radiological assessment of hippocampal sclerosis (HS) from MRI of patients with epilepsy in a setting mimicking clinical reality. METHODS: The study included 40 patients with epilepsy, among them 20 with structural abnormalities in the mesial temporal lobe (13 with HS). Six raters blinded to the diagnosis assessed the 3T MRI in two rounds, first using MRI only and later with both MRI and the QReport. Results were evaluated using inter-rater agreement (Fleiss' kappa [Formula: see text]) and comparison with a consensus of two radiological experts derived from clinical and imaging data, including 7T MRI. RESULTS: For the primary outcome, diagnosis of HS, the mean accuracy of the raters improved from 77.5% with MRI only to 86.3% with the additional QReport (effect size [Formula: see text]). Inter-rater agreement increased from [Formula: see text] to [Formula: see text]. Five of the six raters reached higher accuracies, and all reported higher confidence when using the QReports. CONCLUSION: In this pre-use clinical evaluation study, we demonstrated clinical feasibility and usefulness as well as the potential impact of a previously suggested imaging biomarker for radiological assessment of HS.

Symptomatic visual snow in acute ischemic stroke: A case series.

Visual snow is the main symptom of visual snow syndrome, a disorder of predominantly visual disturbances initially described in patients without abnormalities on ancillary investigations. We present a case series of patients with visual snow in the setting of acute ischemic stroke. The first and second patient reported previous episodic visual snow with migraine attacks. The third patient experienced visual snow for the first time during the ischemic stroke. In the first patient, the ischemic stroke affected the right and left precuneus and the right lingual gyrus. In the second patient, the ischemic stroke was located in the left lingual gyrus, parts of the left fusiform and parahippocampal gyrus, left dorso-lateral thalamus, and left cerebellar hemisphere. In the third patient, occipital pole, trunk of the corpus callosum on the right, right paramedian pons, right cerebellar hemisphere, and vermis were affected. Our case series indicates that the symptom visual snow can be caused by vascular lesions in areas of visual processing. Because patients did not meet criteria for visual snow syndrome, dysfunction in the affected areas might only explain part of the complex pathophysiology of visual snow syndrome.

The Self in the Mind's Eye: Revealing How We Truly See Ourselves Through Reverse Correlation.

Is there a way to visually depict the image people "see" of themselves in their minds' eyes? And if so, what can these mental images tell us about ourselves? We used a computational reverse-correlation technique to explore individuals' mental "self-portraits" of their faces and body shapes in an unbiased, data-driven way (total N = 116 adults). Self-portraits were similar to individuals' real faces but, importantly, also contained clues to each person's self-reported personality traits, which were reliably detected by external observers. Furthermore, people with higher social self-esteem produced more true-to-life self-portraits. Unlike face portraits, body portraits had negligible relationships with individuals' actual body shape, but as with faces, they were influenced by people's beliefs and emotions. We show how psychological beliefs and attitudes about oneself bias the perceptual representation of one's appearance and provide a unique window into the internal mental self-representation-findings that have important implications for mental health and visual culture.

Relating movements in aesthetic spaces: Immersing, distancing, and remembering.

According to Aby Warburg, the aesthetic experience is informed by a pendulum-like movement of the observer's mind that allows him to immerse as well as to take distance from the artwork's composing elements. To account for Warburg's definition, we are proposing embodied simulation and associative processing as constitutive mechanisms of this pendulum-like movement within the aesthetic experience that enable the observer to relate to the displayed artistic material within aesthetic spaces. Furthermore, we suggest that associative processing elicits constructive memory processes that permit the development of a knowledge within which the objects of art become part of memory networks, potentially informing future ways of thinking, feeling, and behaving in real-world situations, as an individual or collectively.

Compensatory eye and head movements of patients with homonymous hemianopia in the naturalistic setting of a driving simulation.

Homonymous hemianopia (HH) is a frequent deficit resulting from lesions to post-chiasmal brain structures with a significant negative impact on activities of daily living. To address the question how patients with HH may compensate their visual field defect in a naturalistic environment, we performed a driving simulation experiment and quantitatively analyzed both eye and head movements using a head-mounted pupil camera. 14 patients with HH and 14 matched healthy control subjects participated in the study. Based on the detection performance of dynamically moving obstacles, which appeared unexpectedly along the sides of the road track, we divided the patient group into a high- and a low-performance group. Then, we compared parameters of eye and head movements between the two patient groups and the matched healthy control group to identify those which mediate successful detection of potentially hazardous objects. Differences in detection rates could not be explained by demographic variables or the extent of the visual field defect. Instead, high performance of patients with HH in the naturalistic setting of our driving simulation depended on an adapted visual exploratory behavior characterized by a relative increase in the amplitude and a corresponding increase in the peak velocity of saccades, widening horizontally the distribution of eye movements, and by a shift of the overall distribution of saccades into the blind hemifield. The result of the group comparison analyses was confirmed by a subsequent stepwise regression analysis which identified the horizontal spread of eye movements as single factor predicting the detection of hazardous objects.

Age-related changes in visual exploratory behavior in a natural scene setting.

Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

Driving simulation in the clinic: testing visual exploratory behavior in daily life activities in patients with visual field defects.

Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily life, despite similar visual deficits. We assume this could be due to variable development of compensatory strategies such as altered visual scanning behavior. Scanning compensatory therapy (SCT) is studied as part of the visual training after infarction next to vision restoration therapy. SCT consists of learning to make larger eye movements into the blind field enlarging the visual field of search, which has been proven to be the most useful strategy(1), not only in natural search tasks but also in mastering daily life activities(2). Nevertheless, in clinical routine it is difficult to identify individual levels and training effects of compensatory behavior, since it requires measurement of eye movements in a head unrestrained condition. Studies demonstrated that unrestrained head movements alter the visual exploratory behavior compared to a head-restrained laboratory condition(3). Martin et al.(4) and Hayhoe et al.(5) showed that behavior demonstrated in a laboratory setting cannot be assigned easily to a natural condition. Hence, our goal was to develop a study set-up which uncovers different compensatory oculomotor strategies quickly in a realistic testing situation: Patients are tested in the clinical environment in a driving simulator. SILAB software (Wuerzburg Institute for Traffic Sciences GmbH (WIVW)) was used to program driving scenarios of varying complexity and recording the driver's performance. The software was combined with a head mounted infrared video pupil tracker, recording head- and eye-movements (EyeSeeCam, University of Munich Hospital, Clinical Neurosciences). The positioning of the patient in the driving simulator and the positioning, adjustment and calibration of the camera is demonstrated. Typical performances of a patient with and without compensatory strategy and a healthy control are illustrated in this pilot study. Different oculomotor behaviors (frequency and amplitude of eye- and head-movements) are evaluated very quickly during the drive itself by dynamic overlay pictures indicating where the subjects gaze is located on the screen, and by analyzing the data. Compensatory gaze behavior in a patient leads to a driving performance comparable to a healthy control, while the performance of a patient without compensatory behavior is significantly worse. The data of eye- and head-movement-behavior as well as driving performance are discussed with respect to different oculomotor strategies and in a broader context with respect to possible training effects throughout the testing session and implications on rehabilitation potential.