Academic literature on the topic 'Non-Visual function'

Since the discovery of the non–image-forming visual system, tremendous research efforts have been dedicated to understanding its mechanisms and functional roles. Original functions associated with the melanopsin system include the photoentrainment of circadian sleep-wake cycles and the pupillary light reflex. Recent findings, however, suggest a much broader involvement of this system in an array of physiologic responses to light. This newfound insight into the underlying function of the non–image-forming system has revealed the many connections to human pathology and attendant disease states, including seasonal affective disorder, migraine, glaucoma, inherited mitochondrial optic neuropathy, and sleep dysregulation of aging. In this review, the authors discuss in detail the clinical implications of the melanopsin system.

A robust, visual masking test that was developed to be feasible with functional magnetic resonance imaging (fMRI) was used to examine the visual cortical inhibitory function in migraine patients with visual aura at both psychophysical and cortical levels. The study showed that the decreased visibility of a visual target was associated with a reduction in cortical activation in the primary visual cortex. The suppression of the transient on-response and after-discharge of neurons to the target was most likely to be responsible for reducing cortical activation, rendering the target less visible or invisible. The migraine patients were equally susceptible to visual masking and showed no difference in cortical activation when compared with age- and sex-matched non-headache controls, demonstrating that visual cortical inhibitory function was not impaired under the experimental conditions. Although these results are not in conflict with the general cortical hyperexcitability theory in migraine, they provide evidence to show the limitation to the theory.

Purpose: To examine the wavelength characteristics of photochromic contact lenses (CL) and evaluate the impact of tinting on visual function in indoor, outdoor, and glare environments. Methods: A total of 33 healthy individuals with refractive errors were recruited and fully corrected for refractive errors. Three groups were established, including non-activated photochromic CL, activated photochromic CL, and lenses without photochromic properties, which replicated the dimming characteristics of CL. Visual acuity and contrast sensitivity were measured and compared among the three groups. Results: Statistically significant differences were observed in the spatial frequency (6, 12 cpd) and contrast sensitivity outdoors, with improved values recorded in the activated photochromic-CL group. In subsequent comparisons, the activated-photochromic-CL group demonstrated significantly better contrast-sensitivity values than the non-photochromic-CL group, as well as significant improvement in contrast sensitivity compared to the non-activated-photochromic-CL group. No significant differences were observed in the indoor or outdoor visual acuity. Conclusion: Our results suggest that photochromic CL enhances visual function in outdoor environments, while maintaining visual function indoors and under glare, thereby improving the quality of vision (QOV) in severe light conditions where exposure to sunlight and ultraviolet light is anticipated.

This study aimed to clarify the relationship between visual acuity and motor function in younger and elderly participants and to compare differences between non-elderly and elderly participants. In total, 295 participants who underwent visual and motor functional examinations were included; participants with visual acuity ≥0.7 were assigned to the normal group (N group) and those with visual acuity ≤0.7 were assigned to the low-visual-acuity group (L group). Motor function was compared between the N and L groups; the analysis was performed by grouping participants into those aged >65 years (elderly) and those aged <65 years (non-elderly). The non-elderly group (average age, 55.6 ± 6.7 years) had 105 and 35 participants in the N and L groups, respectively. Back muscle strength was significantly lower in the L group than in the N group. The elderly group (average age, 71.1 ± 5.1 years) had 102 and 53 participants in the N and L groups, respectively. Gait speed was significantly lower in the L group than in the N group. These results reveal differences in the relationship between vision and motor function in non-elderly and elderly adults and indicate that poor vision is associated with lower back-muscle strength and walking speed in younger and elderly participants, respectively.

La lumière influence de nombreuses fonctions comportementales et physiologiques, comme les cycles veille-sommeil, la sécrétion de mélatonine, le réflexe pupillaire et le métabolisme du glucose. En tant que facteur environnemental clé, elle synchronise le système circadien sur un cycle de 24 heures. Les signaux lumineux sont perçus par les cellules ganglionnaires rétiniennes intrinsèquement photosensibles (ipRGCs), distinctes des bâtonnets et cônes responsables de la vision. Ces ipRGCs envoient les informations lumineuses au noyau suprachiasmatique (NSC) de l'hypothalamus, l'horloge circadienne principale du cerveau. Le NSC projette vers diverses structures cérébrales pour coordonner les processus rythmiques. Cependant, les ipRGCs influencent aussi directement des fonctions non visuelles, comme le sommeil et le métabolisme, en contournant la régulation circadienne. Cette double voie, circadienne et non circadienne, régule les effets non visuels de la lumière. Toutefois, les mécanismes précis par lesquels la lumière affecte les états veille-sommeil restent encore méconnus, de même que les structures cérébrales et les neurotransmetteurs impliqués. La lumière artificielle, omniprésente dans la vie moderne, notamment la nuit, perturbe les cycles naturels jour/nuit, ce qui suscite des inquiétudes.Notre projet vise à comprendre les effets de la lumière sur la veille et le sommeil en utilisant des modèles animaux et des études humaines. Dans nos expériences sur des souris génétiquement modifiées, nous avons étudié si l'orexine et l'histamine jouent un rôle dans les effets inducteurs du sommeil de la lumière. Les souris ont été exposées à différents cycles lumineux (LD12:12, DD et LD1:1). Nous avons observé que la lumière augmentait le sommeil à ondes lentes (SWS) durant la phase sombre chez les souris sauvages (WT), mais cet effet était atténué chez les souris knock-out OX, HDC et OX/HDC. La lumière augmentait également l'activité delta de l'EEG pendant le SWS chez les souris WT, OX knock-out et OX/HDC knock-out, mais pas chez les souris HDC knock-out. De plus, la lumière induisait un sommeil rapide et durable chez les souris WT, alors que cet effet était plus lent et de plus courte durée chez les modèles knock-out, suggérant que la transmission de l'orexine et de l'histamine est nécessaire pour les effets inducteurs de la lumière. Dans l'étude humaine, 20 hommes en bonne santé ont été exposés à quatre intensités lumineuses (0, 3, 8 et 20 lux) pendant 5 jours dans un environnement contrôlé. Nous avons constaté que le réveil après l'endormissement (WASO) était plus long sous 20 lux comparé aux intensités lumineuses plus faibles, et que l'efficacité du sommeil était réduite sous 20 lux. Les niveaux de mélatonine et de cortisol au réveil n'ont pas varié entre les conditions lumineuses. En revanche, la fréquence cardiaque (HR) a diminué et la variabilité de la fréquence cardiaque (HRV) a augmenté sous 20 et 3 lux par rapport à 0 lux. Le taux de glucose durant le sommeil était plus élevé sous faible lumière (3 et 20 lux) que sous 0 lux. De plus, l'exposition nocturne à la lumière a altéré la sensibilité à la lumière et la performance cognitive le lendemain. Nous concluons que même une faible intensité de lumière artificielle nocturne (ALAN) peut perturber le sommeil et affecter les fonctions physiologiques
Light influences a wide range of behavioral and physiological functions, including sleep-wake cycles, melatonin secretion, pupil light reflex, glucose metabolism, and more. As a key environmental factor, light synchronizes the circadian system with a roughly 24-hour cycle. Light signals are detected by a specific type of retinal cell, intrinsically photosensitive retinal ganglion cells (ipRGCs), which are distinct from the classical photoreceptors—rods and cones—that are primarily involved in vision. These ipRGCs transmit light information to the brain's master circadian clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN then projects to various brain structures, coordinating rhythmic behavioral and physiological processes. Notably, ipRGCs also send projections to brain regions beyond the SCN, bypassing circadian regulation to directly influence non-visual functions like sleep, wakefulness, and metabolism. This dual pathway—circadian and non-circadian—mediates light's non-visual effects on the body. However, the exact mechanisms by which light affects sleep-wake states, and which brain structures and neurotransmitters are involved, remain largely unknown. As artificial light becomes increasingly common in modern life, including during nighttime, its disruption of natural light-dark cycles raises concerns. The aim of our project is to explore the wake-promoting and sleep-inhibiting effects of light using both animal models and human studies. In the animal studies, we employed genetically modified mouse models with disrupted histamine and/or orexin transmission to investigate whether these neurotransmitters mediate the sleep-inducing effects of light. Mice were exposed to three conditions: LD12:12, DD, and LD1:1 cycles. Our findings revealed that light significantly increased slow-wave sleep (SWS) during the dark phase in wild-type (WT) mice, but this effect was diminished in OX knockout, HDC knockout, and dual OX/HDC knockout mice. Additionally, light induced a significant increase in EEG delta activity during SWS in WT, OX knockout, and OX/HDC knockout mice, but not in HDC knockout mice. Furthermore, while light induced sleep rapidly and for a sustained duration in WT mice, this effect was slower and shorter-lasting in the knockout models. These results suggest that the sleep-inducing effects of light require both orexin and histamine transmission. In the human study, 20 healthy male participants were exposed to four different light conditions (0, 3, 8, and 20 lux) during a 5-day protocol in a controlled laboratory setting. We found that wake after sleep onset (WASO) was significantly higher under 20 lux compared to lower light intensities, and sleep efficiency was lower under 20 lux than under 3 and 8 lux. Interestingly, there were no significant differences in salivary melatonin and cortisol levels at wake time between the four light conditions. Similarly, body temperature during sleep remained unchanged across light conditions, but heart rate (HR) and heart rate variability (HRV) were affected, with a decrease in HR and an increase in HRV under 20 lux and 3 lux compared to 0 lux. Glucose levels during sleep were significantly higher under low-light conditions (3 and 20 lux) than under 0 lux. Moreover, nocturnal light exposure impaired sensitivity to light and cognitive performance the following morning. Our study concludes that even very low-intensity artificial light at night (ALAN) can disturb sleep and affect physiological functions

Au cours du développement postnatal, le cortex cérébral présente des périodes temporelles limitées de plasticité élevée, appelées périodes critiques (PC). Ces fenêtres, qui permettent aux circuits neuronaux d'être formés par des stimuli externes, se trouvent dans de nombreuses régions corticales et sont régulées par plusieurs facteurs qui influencent l'équilibre entre excitation et inhibition. La PC la plus étudiée est celle de la dominance oculaire dans le cortex visuel, et le facteur de transcription OTX2 joue un rôle essentiel. OTX2 est transféré à partir de sources extra-corticales vers une classe spécifique d'interneurones, les cellules à parvalbumine (PV), et ce transfert contrôle l'apparition et la fermeture de la CP dans plusieurs régions corticales. Le but de ma thèse était de mettre en évidence les mécanismes qui sous-tendent l'activité non cellulaire autonome d'OTX2 impliquée dans la régulation de la PC. Au cours du développement postnatal, le cortex cérébral présente des périodes temporelles limitées de plasticité élevée, appelées périodes critiques (PC). Ces fenêtres, qui permettent aux circuits neuronaux d'être formés par des stimuli externes, se trouvent dans de nombreuses régions corticales et sont régulées par plusieurs facteurs qui influencent l'équilibre entre excitation et inhibition. La PC la plus étudiée est celle de la dominance oculaire dans le cortex visuel, et le facteur de transcription OTX2 joue un rôle essentiel. OTX2 est transféré à partir de sources extra-corticales vers une classe spécifique d'interneurones, les cellules à parvalbumine (PV), et ce transfert contrôle l'apparition et la fermeture de la CP dans plusieurs régions corticales
During postnatal development, the cerebral cortex has limited temporal periods of high plasticity, called critical periods (CPs). These windows, which allow neural circuitry to be shaped by external stimuli, are found in many cortical regions and are regulated by several factors that influence the balance between excitation and inhibition. The most studied CP is that of ocular dominance in the visual cortex, and the OTX2 homeoprotein transcription factor plays an essential role. OTX2 is transferred from extra-cortical sources into a specific class of interneurons, the parvalbumin (PV) cells, and this transfer controls CP onset and closure in several cortical regions. The aim of my thesis was to reveal the mechanisms underlying OTX2 non-cell autonomous activity implicated in CP regulation. Altogether my work extends our current understanding of cortical plasticity and the role of OTX2 during CPs. I have shown that non-cell autonomous OTX2 regulates cortical postnatal plasticity through direct transcriptional mechanisms and epigenetic modifications

Background: Despite our distinct impression to the contrary, we are only conscious of a fraction of all the neural activity underlying our thoughts and behavior. Most neural processes occur non-consciously, and in parallel with our conscious experience. However, it is still unclear what the limits of non-conscious processes are in terms of higher cognitive functions. Many recent studies have shown that increasingly more advanced functions can operate non-consciously, but non-conscious information is still thought to be fleeting and undetectable within 500 milliseconds. Here we used various techniques to render information non-conscious, together with functional magnetic resonance imaging (fMRI), to investigate if non-consciously presented information can be retained for several seconds, what the neural substrates of such retention are, and if it is consistent with working memory maintenance. Results: In Study I we used an attentional blink paradigm to render stimuli (single letters) non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that non-conscious memory performance was above chance after all delay durations, and showed no signs of decline over time. Univariate fMRI analysis showed that the durable retention was associated with sustained BOLD signal change in the prefrontal cortex and cerebellum during the delay period. In Study II we used continuous flash suppression (CFS) to render stimuli (faces and tools) non-conscious, and a variable delay period (5 or 15 s) prior to memory test. The durable retention of up to 15 s was replicated, and it was found that stimuli identity and spatial position was retained until prospective use. In Study III we used CFS to render tools non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that memory performance was not better than chance. However, by using multi-voxel pattern analysis it was nonetheless possible to detect the presence vs. absence of non-conscious stimuli in the frontal cortex,and their spatial position (left vs. right) in the occipital cortex during the delay. Conclusions: Overall these findings suggest that non-consciously presented information (identity and/or position) can be retained for several seconds,and is associated with BOLD signal in frontal and posterior regions. These findings are consistent with working memory maintenance of non-consciously presented information, and thereby constrain models of working memory and theories of consciousness.

La construction de la représentation de soi est basée sur l'intégration des informations que l'on reçoit des différentes modalités sensorielles telles que les informations visuelles, auditives, tactiles ou proprioceptives. L'interaction entre les actions et les mouvements, et plus récemment les interactions sociales et l'espace ont été étudiées essentiellement au niveau comportemental, moins au niveau fonctionnel et beaucoup reste encore à élucider. En particulier, il est important et essentiel de comprendre exactement quels processus sont impliqués dans la construction d'une représentation spatiale et comment ces processus sont mis en oeuvre, non seulement au niveau local par l'activité de neurones spécifiques, dans une zone corticale spécifique, mais aussi à l'échelle du réseau dans son ensemble ainsi qu'à l'échelle du cerveau entier. Le premier axe de ma thèse s'intéresse à l'espace peripersonnel, qui est l'espace le plus proche de nous et qui représente l'un des sous-espaces fonctionnels de la représentation spatiale. Nous faisons l'hypothèse que ce sont les mêmes régions qui contribuent à la convergence multisensorielle, à la prédiction des conséquences sur le traitement tactile d'une stimulation visuelle approchant le corps et à la construction de l'espace peripersonnel. Pour tester cette hypothèse, nous avons étudié l'effet des aspects prédictifs temporels et spatiaux d'un stimulus visuel dynamique sur la détection du stimulus tactile chez l'Homme (étude comportementale) et le primate non humain (étude en IRM fonctionnelle) ainsi que les bases neuronales de la représentation de l'espace proche et de la représentation de l'espace lointain, chez le primate non humain (étude en IRM fonctionnelle). Nous mettons en évidence l'implication d'un réseau parieto-frontal, essentiellement composé par l'aire intrapariétale ventrale VIP et l'aire prémotrice F4 qui sont activées par ces trois mécanismes différents. Nous proposons que ce réseau traite non seulement la trajectoire de l'objet approchant vis-à-vis du corps, mais qu'il anticipe également ses conséquences sur le corps et prépare des actions de protection en réponse à ce stimulus approchant. Le deuxième axe de ma thèse porte sur la caractérisation de l'étendue de la plasticité dans la représentation visuelle dans le cerveau adulte (par opposition aux premiers stades de plasticité observées autour des périodes critiques du développement) et en particulier, sur des développements méthodologiques permettant de mesurer les changements fins dans le cortex visuel induits par une telle plasticité. Plus précisément, nous avons développé un ensemble de méthodes d'IRM à haute résolution : imagerie fonctionnelle (cartographie visuelle à haute résolution, IRM au repos), pharmacologique (imagerie spectroscopique du GABA) et structurelle (IRM anatomique, DTI basée sur la diffusion des molécules d'eau), afin de définir des mesures de référence pour évaluer les changements induits par la plasticité à différents moments après son induction, à travers une étude longitudinale réalisée chez les mêmes animaux. Certaines de ces méthodes nécessitent encore quelques raffinements et ajustements mais, dans l'ensemble, elles montrent leur potentiel prometteur pour étudier la plasticité chez les primates non humains. Dans l'ensemble, ce travail de thèse a permis de créer un lien fonctionnel entre les études d'IRMf effectuées chez l'Homme et les études d'enregistrement d'électrophysiologies chez le primate non humain. De plus, il entraine de nouvelles stratégies et pistes d'explorations à étudier dans le domaine de la représentation spatiale, à la fois chez l'Homme et le primate non humain
The construction of the representation of self is based on the integration of information received by our different sensory modalities such as visual, auditory, tactile or proprioceptive information. The interaction between actions and movements and more recently social interactions and space are being explored at the behavioral level, but less so at the functional level and much more remains to be elucidated. In particular, it is important and fundamental to understand exactly which processes are involved in space representation and how, not only from a partial view focusing on specific cortical areas and single neuron processes but at the scale of the whole brain and the functional networks. The first axis of my thesis focuses on peripersonal space, that is the space that is closest to us, and represents one of the functional subspaces of spatial representation. We assume that it is the same regions that contribute to multisensory convergence, to the prediction of the consequences of a looming visual stimulus onto tactile processing and to the construction of peripersonal space. To test this hypothesis, we investigated the effect of the temporal and spatial predictive aspects of a dynamical looming visual stimulus onto tactile stimulus detection in humans (behavioral study) and non-human primates (fMRI study); the neural bases of near space and far space representations, in non-human primate (fMRI study). We highlight the involvement of a parieto-frontal network, essentially composed by the ventral intraparietal area VIP, the premotor area F4 as well as striate and extra-striate cortical regions, which are activated by these three different mechanisms. We propose that this network not only processes the trajectory of the looming object with respect to the body, but also anticipates its consequences onto the body and prepares protective actions in response to the looming stimulus. The second axis of my thesis focuses on characterizing the extent of plasticity in the visual representation of the adult brain (as opposed to the early stages around the critical developmental periods) and in particular, how the associated fine-grained changes in the visual cortex can be precisely quantified along multiple dimensions (anatomical, functional, pharmacological). Specifically, we have developed a set of high-resolution MRI methods to assess functional (high-resolution visual mapping fMRI, rs-MRI), pharmacological (GABA spectroscopy imaging) and structural (anatomical MRI, DTI) imaging to define reference measures against which to evaluate the changes induced by plasticity at different times after its induction, through a longitudinal study performed in the same animals. Some of these methods need to be more refined but they show that they are really promising to study plasticity in nonhuman primate. On the whole, this present doctoral research allows to make a functional link between human fMRI studies and monkey single cell recording studies and provides new strategies and explorations to perform on the spatial representation field both in humans and non-human primates

Gränssnittsdesign är en av de viktigaste aktiviteterna vid systemutveckling, eftersom gränssnittet utgör den beståndsdel för vilket slutanvändare kommer göra sin primära helhetsbedömning av systemet utefter. Det innebär att gränssnittsdesignarbetet har en avgörande roll för hur systemet kommer att mottas och bedömas vid leverans och upphandlingar av system. Att designa tillfredställande gränssnitt handlar om att ta hänsyn till en rad olika human computer interaction (HCI)-aspekter. Dessa är användbarhet, användarupplevelse samt estetik, det vill säga hur visuellt tilltalande gränssnittet är. Följande tre aspekter kommer på olika sätt påverka hur en användare upplever ett system, vilket i sin tur kommer påverka huruvida en beställare är beredd att investera i ett system. Att utveckla gränssnitt för system innebär ofta att designers och utvecklare måste göra avvägningar kring i vilken mån en designer skall få realisera gränssnittsdesign. Detta eftersom en samansättning av för många visuella gränssnittselement kan få inverkan på systemets prestanda. Stundtals hamnar de två elementen, visuella designattribut och systemkrav, i konflikt med varandra och i de fall där de senare föregår designattribut ställs gränssnittsdesigners inför en utmaning eftersom att de bli begränsade i sitt arbete. Trots detta ställs dock samma krav på att designers skall uppnå tilltalande gränssnitt som väcker känslor av professionalism, samtidigt som systemet skall bibehålla optimal systemprestanda och funktionalitet.Syftet med denna studie var att undersöka hur ett tillfredställande gränssnitt i aspekter av estetik, användbarhet och användarupplevelse kan designas i ett standardsystem när designarbete begränsas till att enbart kunna justera placering och färg av gränssnittselement. Detta har inneburit en designforskningsansats bestående av en iterativ utvecklingsprocess där ett gränssnitt designat och realiserat baserat på av teorin förslagna riktlinjer för gränssnittsdesign som fortfarande har varit möjliga att tillämpa trots designarbetets begränsningar. Gränssnittet har därefter utvärderats genom experiment i form av användbarhetstester och expertutvärdering. Empirisk data från utvärderingarna har därefter analyserats och införlivats i gränssnittet och slutligen har en slutsats genererats och presenterats.Studiens resultat visar att genom en kombination av befintliga teoribaserade riktlinjer kommer designers en god bit på väg för att lyckas design tillfredställande gränssnitt i aspekter av estetik, användbarhet och användarupplevelse. I slutet av studien presenteras detta i form av sju nya riktlinjer. Variabeln användarupplevelse visade sig dock vara svårare att designa för i studiens begränsade kontext. Detta beror på att användarupplevelse är en svår variabel att utvärdera på grund av dess subtila natur. Slutligen presenteras förslag för framtida forskning och på vilket sätt studiens resultat vidare bör beprövas.
User-Interface design is one of the most important aspects of development of a system, as the user-interface is one of the elements that the user primarily will take in consideration when assessing a system. This means that user-interface design plays an important role in how the system will be received and assessed at procurement. A designer has to consider a couple of human computer interaction (HCI)-aspects such as usability, user experience, and aesthetics, in order to design a satisfactory user-interface. These three aspects of human computer interaction affect user experience of a system, which will influence a client’s decision on investment in the system. Designing a user-interface of a system often means that designers and developers have to consider the extent to which a designer can implement their version of the interface. A composition of many visual interface elements can have an impact on the systems performance. Sometimes the visual design attributes can conflict with the system requirements. If designers are challenged system requirements are prioritised because they will be limited in their work. Despite those limitations, the designers are still needed to design an appealing user-interface that can invoke feelings of professionalism, parallel to the system requirement of optimal performance and functionality.The purpose of this study was to explore how an appealing user-interface with regards to aesthetics, usability and user experience can be designed when the design work is limited to only be able to adjust placement and visual appearance in terms of names and colour of UI elements. This has been explored by doing an iterative development process in which an interface has been designed and developed based on guidelines from theory on user-interface design which the authors has been able to implement based on the limitations on the design work. The interface has subsequently been evaluated by experiments in terms of usability tests and an expert evaluation in the form of a heuristic evaluation. The evaluations resulted in empirical data which has been analysed and set against existing theory upon which a conclusion has been generated and presented.The result of the study show that designers are well on the way to successfully design an appealing user-interface in relation to aesthetic, usability and user experience, which the authors presents in the form of seven new guidelines. The variable user experience turned out to be more difficult to design in the study’s limited context. The authors believe that one of the reasons for this is that user experience is difficult to evaluate because of its subtle nature. Lastly we present suggestions for future research and how the results of the study should be further proved.

Les personnes non-voyantes montrent dans les différents aspects de leurs vies qu’elles sont capables de s’adapter à la privation visuelle en utilisant les capacités intactes comme l’ouï ou le toucher. Elles montrent qu’elles peuvent bien évoluer dans leur environnement en absence de vision et démontrent même des fois des habiletés supérieures à celles des personnes voyantes. La recherche de ces dernières décennies s’est beaucoup intéressée aux capacités adaptatives des non-voyants surtout avec l’avènement des nouvelles techniques d’imagerie qui ont permis d’investiguer des domaines qui ne l’étaient pas ou l’étaient difficilement avant. Les capacités supérieures des non voyants dans l’utilisation plus efficace des informations auditives et tactiles semblent avoir leur base neuronale dans le dans le cortex visuel désafférenté, qui continu à être fonctionnel après la privation sensorielle et s’en trouve recruté pour le traitement de stimulations dites intermodales : auditives, tactiles et même montre une implication dans des processus de plus haut niveau, comme la mémoire ou le langage. Cette implication fonctionnelle intermodale résulte de la plasticité du cortex visuel c'est-à-dire sa capacité à changer sa structure, sa fonction et d’adapter ses interactions avec les autres systèmes en l’absence de vision. La plasticité corticale n’est pas exclusive au cortex visuel mais est un état permanent de tout le cerveau. Pour mesurer l’activité du cortex visuel des non voyants, une mesure d’excitabilité de ses neurones consiste à mesurer le temps de recouvrement de l’onde N1 en potentiels évoqués, qui est plus rapide chez les non voyants dans la modalité auditive. En effet, les réponses en potentiels et champs évoqués ont été utilisés en EEG/MEG pour mettre en évidence des changements plastiques dans le cortex visuel des non-voyants pour le traitement de stimuli dans les modalités auditives et tactiles. Ces réponses étaient localisées dans les régions postérieures chez les non voyants contrairement aux contrôles voyants. Un autre type de réponse auditive a reçu moins d’intérêt dans la recherche concernant la réorganisation fonctionnelle en relation avec la privation sensorielle, il s’agit de la réponse auditive oscillatoire (Auditory Steady-State Response ASSR). C’est une réponse qui a l’avantage d’osciller au rythme de stimulation et d’être caractérisé par une réponse des aires auditives étiquetée à la fréquence de stimulation. Cette étiquette se présente sous la forme qu’un pic d’énergie spectrale important qui culmine aux fréquences présentes dans la stimulation. Elle a également l’avantage d’être localisée dans les régions auditives primaires, de là tout changement de localisation de cette réponse chez des non voyants en faveur des régions visuelles pourrait être considéré comme une évidence de la réorganisation fonctionnelle qui s’opère après une privation sensorielle précoce. Le but de cette thèse est donc d’utiliser la réponse oscillatoire à l’écoute des sons modulés en amplitude (MA) pour mettre en évidence les corrélats de la réorganisation fonctionnelle dans le cortex visuel des non-voyants précoces. La modulation de la réponse auditive dans les régions visuelles nous permettra de montrer qu’une réorganisation est possible chez les non-voyants pour ce traitement intermodal. La première étude est une validation du paradigme expérimental «frequency tagged sounds». Il s’agit de montrer qu’une tâche de détection de changement dans la stimulation, permet de moduler la réponse ASSR aux sons modulés en amplitude en vue de l’utiliser dans les études chez les non voyants et dans les conditions d’une privation visuelle transitoire (avec les yeux bandés). Un groupe de sujets voyants ont réalisé une tâche de détection de changement dans la stimulation les yeux ouverts dans deux conditions : écoute active qui consiste à détecter un changement dans la fréquence porteuse de la modulation en appuyant avec l’index droit sur un bouton de réponse et une condition d’écoute passive. Les sons étaient présentés en écoute monaurale et dichotique. Les résultats ont montré une différence significative à l’occurrence du changement dans la stimulation en écoute dichotique seulement. Les schémas de plus grande réponse controlatérale et de suppression binaurale décrit dans la littérature ont été confirmés. La deuxième étude avait pour but de mettre en évidence une réorganisation rapide de la réponse ASSR chez un groupe de sujets voyants dans les conditions de privation visuelle transitoire de courte durée, par bandage des yeux pendant six heures. Le même protocole expérimental que la première étude a été utilisé en écoute active seulement. Les résultats montrent que dans ces conditions une modulation de la réponse corticale en écoute dichotique dans les régions visuelles est possible. Ces sources d’activité occipitale adoptent une propriété du cortex auditif qui est le battement binaural, c'est-à-dire l’oscillation de la réponse ASSR à la différence des fréquences présentées dans chaque oreille. Cet effet est présent chez la moitié des sujets testés. La représentation corticale des sources occipitales évolue durant la période de privation et montre un déplacement des sources d’activité dans la direction antéropostérieure à la fin de la période de privation. La troisième étude a permis de comparer le traitement de la réponse ASSR dans un groupe de non-voyants congénitaux à un groupe de voyants contrôles, pour investiguer les corrélats de la réorganisation fonctionnelle de cette réponse après une privation sensorielle de longue durée c'est-à-dire chez des non voyants congénitaux. Les résultats montrent des différences significatives dans la représentation spectrale de la réponse entre les deux groupes avec néanmoins des activations temporales importantes aussi bien chez les non voyants que chez les contrôles voyants. Des sources distribuées ont été localisées dans les régions associatives auditives dans les deux groupes à la différence des non voyants où il y avait en plus l’implication des régions temporales inférieures, connues comme étant activées par la vision des objets chez les voyants et font partie de la voie visuelle du quoi. Les résultats présentés dans le cadre de cette thèse vont dans le sens d’une réorganisation rapide de la réponse auditive oscillatoire après une privation visuelle transitoire de courte durée par l’implication des régions visuelles dans le traitement de la réponse ASSR par l’intermédiaire du démasquage de connections existantes entre le cortex visuel et le cortex auditif. La privation visuelle de longue durée, elle conduit à des changements plastiques, d’une part intra modaux par l’extension de l’activité aux régions temporales supérieures et médianes. D’autre part, elle induit des changements inter modaux par l’implication fonctionnelle des régions temporales inférieures visuelles dans le traitement des sons modulés en amplitude comme objets auditifs alors qu’elles sont normalement dédiées au traitement des objets visuels. Cette réorganisation passe probablement par les connections cortico-corticales.
Blind persons show in their everyday life that they can efficiently adapt to visual deprivation by relying on their spared senses like touch or the sense of hearing. They also show they can challenge their environment without vision and sometimes even demonstrate superior abilities compared to sighted counterparts. In the last decades, research got more interested in adaptive capabilities of the blinds especially with the advent of new imaging techniques which made it possible to make giant steps investigating new avenues in the field of brain plasticity after sensory loss. The superior abilities of blind individuals take the form of a more efficient use of auditory and tactile information and find their neuronal correlates in the deafferented visual cortex. The visual cortex of the blind is still highly functional after visual deprivation and is recruited for the processing of cross modal auditory and tactile stimulations. It can even show implication in higher level memory or language processes. This functional involvement results from the plasticity of the visual cortex which is its ability to change its structure, its function and to adapt its interactions with the other systems in the absence of vision. Cortical plasticity is not exclusive to the visual cortex of the blind but is a permanent state of the brain. To appreciate cortical activity in the visual cortex of blind individuals, a measure of excitability of its neurons is used. This measure is represented by the recovery of the N1 component in ERPs to target detection, which is shorter in the auditory modality for the blind. Evoked potentials and evoked fields components in EEG and MEG have been shown to be reorganized in favour of the visual cortex of blind individuals compared to sighted ones for the auditory and tactile modalities. Posterior location for such components was found in the blind. The auditory steady-state response is another brain response that received less interest in the study of cortical reorganization after sensory loss. The ASSR has the advantage of oscillating at the stimulation rhythm and is characterized by a response in the auditory cortices tagged to the stimulation frequencies. The tag takes the form of an important spectral energy peak at the frequencies of stimulation in auditory areas. The ASSR is localized in left and right primary auditory areas, with this regard any posterior shift in the location of source activity in blind individuals also tagged to stimulation frequencies would be considered as an evidence of functional reorganization following sensory deprivation. The objectives of this work are to make use of the characteristics of the ASSR to amplitude modulated tones (AM) to investigate neural correlates of cross modal functional reorganization in the visual cortex of the blind for the processing of AM tones. The first study is a validation of the frequency tagging paradigm. A change detection auditory task can modulate the envelope amplitude of the ASSR response. The same paradigm is used to investigate cross modal reorganisation after long and short term visual deprivation. In this first study a group of healthy sighted individuals detected a change in the carrier frequency of AM tones, with eyes opened during monaural and dichotic listening. Two conditions were tested an active condition where they had to press a button each time they hear the change and a passive condition. Results show a significant increase in the envelope amplitude of the ASSR to the onset of the carrier frequency change, only for dichotic presentation. Patterns of activations of the ASSR were maintained, with larger responses in the hemisphere contralateral to the stimulated ear and binaural suppression for the ipsilateral inputs for the dichotic presentation. The second study was aimed to show that rapid changes in the ASSR to amplitude modulated tones (MA) are possible after short term sensory deprivation, by blindfolding sighted individuals for six hours. The same detection task was used but not the passive condition. Results show a modulation of the dichotic response in visual areas. The occipital source activity found, showed an auditory property as a binaural beat, which means an oscillating ASSR at a frequency equal to the difference of the frequencies presented to each ear. This effect was present in half of the participants and took place at the end of the blindfolding time. Cortical representation of the occipital sources showed a displacement of source activities in the antero-posterior direction at the end of transitory deprivation period. In the third study we compared the ASSR processing between early blind individuals (congenitally blind) group and healthy sighted controls group, to investigate the neural correlates of functional reorganization of this response after long term visual deprivation. Results show significant differences in the spectral representation of the response between the two groups. Important auditory temporal activations were found in the two groups. Distributed sources were localized in primary and secondary auditory areas for the two groups. A difference was found in blind individuals who showed additional activations of inferior temporal areas, known to be activated by objects vision in sighted individuals and being part of the what visual pathway. The results presented here are in line with a rapid reorganization of the ASSR after short term visual deprivation, and the implication of visual areas in the processing of AM tones for long term sensory deprivation in the congenitally blind. This was made possible by the unmasking of existing connections between auditory and visual cortices. Long term deprivation leads to plastic changes, in the auditory modality as a first step by the extension of activity to superior and middle temporal areas, then to cross modal changes with the functional involvement of inferior temporal areas in the processing of AM tones, considered as visual objects. This reorganization is likely to be mediated through lateral cortico-cortical connections.

Attention is the ubiquitous construct referring to the ability of the brain to focus resources on a subset of perceptual input which it is trying to process for a response. Attention has for a long time been studied with reference to its distribution across space where, for example, visual input from an attentionally monitored location is given preference over non-monitored (i.e. attended) locations. More recently, attention has been studied for its ability to select targets from among rapidly, sequentially presented non-targets at a fixed location, e.g. in visual space. The present chapter explores this latter function of attention for its relevance to behaviour. In so doing, it highlights what is becoming one of the most popular approaches to studying communication across the brain—oscillations—at various frequency ranges. In particular the authors discuss the alpha frequency band (8–12 Hz), where recent evidence points to an important role in the switching between processing external vs. internal events.

Perception is the first form of representational mind to emerge in evolution. Three types of form are discussed: formal representational structure of perceptual states, formation characteristics in computations of perceptual states, and the form of the visual and visuomotor systems. The book distinguishes perception from non-perceptual sensing. The formal representational structure of perceptual states is developed via a systematic semantics for them—an account of what it is for them to be accurate or inaccurate. This semantics is elaborated by explaining how the representational form is embedded in an iconic format. These structures are then situated in what is known about the processing of perceptual representations, with emphasis on formation of perceptual categorizations. Features of processing that provide insight into the scope of the perceptual (paradigmatically visual) system are highlighted. Relations between these processes and associated perceptual-level capacities—conation, attention, memory, anticipation, affect, learning, imagining—are delineated. Roughly, a perceptual-level capacity is one that borrows its form and content from perception and involves processing that is no more complex or sophisticated than processing that occurs in the classical visual hierarchy. Relations between perception and these associated perceptual-level capacities are argued to occur within the perceptual and perceptual-motor systems. An account of what it is to occur within these systems is elaborated. An upshot is refinement of the distinction between perceptual-level capacities, on one hand, and thought and conception, on the other. Intermediate territory between perception-level representation and propositional thought is explored. The book is resolutely a work in philosophy of science. It attempts to understand perception by focusing on its form, function, and underlying capacities, as indicated in the sciences of perception, rather than by relying on introspection or ordinary talk about perception.

In the philosophy of neuroscience, much attention has been paid to mechanistic causal explanations, both in terms of their theoretical virtues, and their application in potential therapeutic interventions. Non-mechanistic, non-causal explanatory models, it is often assumed, would have no role to play in any practical endeavors. This assumption ignores the fact that many of the non-mechanistic explanatory models which have been successfully employed in neuroscience have their origins in engineering and applied sciences, and are central to many new neuro-technologies. This chapter examines the development of explanations of lateral inhibition in the early visual system as implementing an efficient code for converting photoreceptor input into a data-compressed output from the eye to the brain. Two applications of the efficient coding approach are considered: in streamlining the vast datasets of current neuroscience by offering unifying principles, and in building artificial systems that replicate vision and other cognitive functions.

The first section discusses definitions of the graphic sign and its typologies, and provides an overview of relevant academic literature. The second section highlights major historiographic trends in the study of graphic signs in the humanities from the early twentieth century to the present day. The next section outlines the relation of graphic signs to a wider corpus of graphic non-figurative data in the late antique Mediterranean and early medieval Europe with reference to the overarching methodological framework of visual thinking and graphic visualization and the related concept of early graphicacy, focusing particularly on the latter’s general cognitive aspects and intrinsic connection to the late antique and early medieval cultural system of visual representation. The concluding section defines the book’s subject, namely graphic signs of authority, outlines their functional usage in early medieval political culture, and summarizes the content of the following chapters.

Some mental states seem to be "of" or "about" things or to "say" something. For example, a thought might represent that grass is green, and a visual experience might represent a blue cup. This is intentionality. The aim of this book is to explain this phenomenon. Once we understand intentionality as a phenomenon to be explained, rather than a posit in a theory explaining something else, we can see that there are glaring empirical and in-principle difficulties with currently popular tracking and functional role theories of intentionality, which aim to account for intentionality in terms of tracking relations and functional roles. This book develops an alternative theory, the phenomenal intentionality theory (PIT), on which the source of intentionality is none other than phenomenal consciousness, the subjective, felt, or qualitative aspect of mental life. While PIT avoids the problems that plague tracking and functional role theories, it faces its own challenges in accounting for the rich and complex contents of thoughts and the contents of nonconscious states. In responding to these challenges, this book proposes a novel version of PIT, one on which all intentionality is phenomenal intentionality, though we in some sense represent many non-phenomenal contents by ascribing them to ourselves. This book further argues that phenomenal consciousness is an intrinsic feature of mental life, resulting in a view that is radically internalistic in spirit: Our phenomenally represented contents are literally in our heads, and any non-phenomenal contents we in some sense represent are expressly targeted by us.

Krokodil produced state-sanctioned satirical comments on Soviet and international affairs from 1922 onward. Authored by professional and non-professional contributors, and published by Pravda in Moscow, it became the satirical magazine with the largest circulation in the world. Every Soviet citizen and every scholar of the USSR was familiar with Krokodil as the most significant and influential source of graphic satire in the USSR. This book uses an original framework for reconsidering the forms, production, consumption, and functions of Krokodil magazine. It considers the magazine's content, structures and conventions; it also uses modern cultural and media theory to look beyond content analysis to consider visual language and the performative construction of character. Empirical analysis of Krokodil is thus used to extend and nuance our understanding of Soviet graphic satire beyond state-sponsored propaganda. In several ways, this book challenges existing approaches. It conducts close readings of a large range of different types of cartoons that have not before been discussed in depth, and it does so in ways that reveal new insights. It shows that Krokodil's satire was complex, subtle and intermedial. It highlights the importance of Krokodil's readers' and artists' collaborative exploration and shaping of the boundaries of permissible discourse, and it argues that Krokodil's cartoons simultaneously affirmed, refracted and critiqued official discourses, counterposing them with visions of Soviet citizens' responses. Ideology, Krokodil's satire suggests, is an interpretive tool for negotiating everyday reality and official discourses, and it was not always to be taken seriously.

esistance features a selection of overtly non-conformist positions in the contemporary visual art scene of Albania vis-à-vis the most recent social, political, and economic turmoils in the Western Balkans – a region marked by the dark side of political governances that have remained “democratic” in their outward appearance (especially toward the European Union), while dramatically leaning toward autocratic regimes in the eyes of their own citizens. Regardless of their citizens’ primary interests, and despite some positive signals surfacing in the international media, almost every attempt to establish lasting conditions for democratic governance in the Western Balkans has been shrouded in the veil of profit-driven political scandals, personal greed for more and more power over the people’s rights, and the extinction of public property in pursuit of social elite’s corporate and private interests. Additionally, and more specifically related to Tirana, artists and citizens have, over the years, been involved in various types of revolt, expressing their disagreements with the ongoing destruction of public property in the name of “modernization and development”: a movement led by local political powers through financially and strategically motivated processes of architectural cannibalism – not only at the expense of erasing Albanian cultural heritage or long-term residents’ habitats, but also at the expense of taking human lives under the pretext of “urbanization.” The most obvious instance of this economy of destruction was the complex of buildings linked to the National Theater of Albania in downtown Tirana that has served as a symbolic and material place of citizens’ resistance: for more than two years, together with local artists, they have been opposing the government’s plans to demolish the old complex in order to build a new one – until this finally happened in Spring 2020, in the midst of the ongoing COVID19 pandemic. Rooted in the atmosphere of the National Theater Protests in Tirana, RESISTANCE was conceived in Summer 2019 by ZETA Center for Contemporary Art as the International Artists-in-Residence Program, in cooperation with three partner organizations from Kosovo, Serbia and North Macedonia (Stacion – Center for Contemporary Art in Prishtina; Ilija & Mangelos Foundation in Novi Sad; and Faculty of Things That Can’t Be Learned in Bitola) and supported by Swiss Cultural Fund in Albania, a project of the Swiss Agency for Development and Cooperation. Gradually, the project expanded into an exhibition (Heterotopias of Resistance, curated by Blerta Hoçia and featuring works by Lori Lako, Fatlum Doçi, Edona Kryeziu, Nina Galiç, Darko Vukiç, Nikola Slavevski, and Natasha Nedelkova) and a series of interviews and panel discussions (with contributions by Lindita Komani, Edmond Budina, Ervin Goci, Ergin Zaloshnja, Pleurad Xhafa, Gentian Shkurti, Stefano Romano, Luçjan Bedeni, HAVEIT, Leonard Qylafi, Jonida Gashi, and Fatmira Nikolli). The results of both have been collected and presented in the format of a publication that, besides serving as an indispensable reading material concerning visual arts and politics in contemporary Albania, especially to those abroad, functions by itself as a form of resistance against contagious cultural policies in weak post-socialist “democracies” in Southeastern Europe.

AbstractThis paper investigates the role of 3D modelling in enhancing our understanding of the spatial arrangement and representational character of a room in a 17th century Dutch home. The case study presented here is the entrance hall (“voorhuis” in Dutch) of the house of Pieter de Graeff and Jacoba Bicker located at Herengracht 573 in Amsterdam. This research draws upon a heterogenous dataset which includes the surviving architecture, the probate inventory of De Graeff’s properties that was drawn up after his death, and the almanacs in which he recorded some of the construction works in the house. This paper shows how the “materialization” of the inventoried objects in a 3D model suggests otherwise unnoticeable intentions and visual cues underlying their disposition within the room. In addition, this approach offers a non-intrusive and non-destructive way of visualizing past building phases and a room’s forgotten function which prompts a more dialogical engagement with architectural heritage in comparison to permanent physical reconstructions.

AbstractThe unit overview is focused on the creation of art and aesthetic objects. Given the fact that the line between art and non-art has become thinner and thinner during the last decades, we pursue the creation of a varied number of visual media, ranging from classical portraits to selfie and selfie-editing behaviours. Also, we bring into view authorship issues, arising both from classical art philosophy and contemporary situations, such as AI-generated art. The function and meaning of portraits across the ages is a key part of the discussion in this chapter, treating art as utilitarian and aesthetic at the same time. Moreover, the reasons for creating art lay at the center of trying to analyze art creation from a neurological perspective. Defining the artist/creator and establishing his or her position as aesthetic expert becomes crucial in this respect. We present the current limitations in the field of neuroaesthetics regarding art and portrait creation and we try to re-contextualize research from the perception field of neuroaesthetics and apply it to the art-production field.

Assessment of visual function in human infants and pre-verbal children places the greatest demands upon test efficiency and non-invasiveness. The poor state of development of the behavioral response repertoire and attention span, and the impossibility of communication with the test subject through verbal instructions are each significant obstacles. These difficulties are unfortunately greatest during the critical period for visual development during which the human visual system is the most sensitive to disruption by exogenous factors, and at the same time most receptive to treatment.

Participants may discuss priority topics within each of the NEI program areas for which non-invasive assessment techniques are needed. Information will also be available on current funding rates and budgetary considerations.

Postoperative astigmatism following intraocular lens (IOL) implantation has been found clinically (Jolson & Seidel, 1984) and has been discussed, for example, by Moore (1980), Binkhorst (1979) and Maltzman et al. (1983). Astigmatism, though primarily corneal in origin, may occur elsewhere along the visual axis including the lens implant and position of the fovea relative to the effective optic axis of the eye. Moore compared 100 IOL implant cases with 328 non-implant cases and found that postoperative astigmatism was proportionately far higher in the implant group. Tilting of the IOL was suggested as one of the factors which caused this astigmatism. Binkhorst also suggested that the astigmatism was purely optical. Miller & Doane (1984) presented evidence of tilt or wobble of iris-supported IOL’s due to rotation of the visual axis of the globe. We have determined tilt angle from postmortem cadaver eyes, and have computed the amount of spherical and cylindrical powers that are induced due to the tilt as well as that to lateral movement of the IOL.

Increasing numbers of corneal transplants for visual rehabilitation are being performed throughout the world. The adequacy of visual function in these patients has been assessed only in terms of visual acuity measurement, yet non-acuity parameters such as contrast sensitivity may be important indices of the adequacy of visual performance in these patients for a variety of real-world conditions. Contrast sensitivity may therefore provide a more sensitive clinical indicator of visual function of these patients within the limits of visual resolution.

We have previously demonstrated that functional changes in the visual system accompany fluctuations in blood glucose occurring over minutes or hours. These changes in vision function occur in both diabetic and non-diabetic observers and can be demonstrated psychophysically1 as well as with visually-evoked cortical potentials (VEP's)2.

In an offline kanji handwriting detection and recognition system, the ability of the neural network to correctly recognise each handwritten character within a document tends to be a significant problem. However, the present state-of-the-art neural network adopted for the object detection task settle for the object location principle but cannot achieve complete detection and lacks the proper use of an activation function. Also, there appears to be a lack of research focusing on developing an activation function that can perfectly enhance the learning ability of an artificial neuron used in a deep neural network model. Therefore, this research paper presents a visual evaluation between monotonic and non-monotonic activation function performance effect on a neural network. The results obtained show that the non-monotonic activation functions outperformed the monotonic activation function by achieving a fast speed for detection and recognition of the kanji handwritten characters.

Review question / Objective: Cerebral palsy (CP) is a non-progressive, persistent syndrome occurring in the brain of the fetus or infant[1]. The prevalence of CP is 0.2% worldwide, and the prevalence can increase to 20-30 times in preterm or low birth weight newborns. There are about 6 million children with CP in China, and the number is increasing at a rate of 45,000 per year. Virtual reality (VR) refers to a virtual environment that is generated by a computer and can be interacted with.VR can mobilize the visual, auditory, tactile and kinesthetic organs of CP, so that they can actively participate in the rehabilitation exercise. Information sources: Two researchers searched 5 databases, including Pubmed (N=82), Embase (N=191), The Cochrane Library (N=147), Web of Science (N=359) and CNKI (N=11).

Review question / Objective: Objective: The aim of this umbrella review is to address the question: “What interventions are effective for maximising domains of the intrinsic capacity of older adults in an outpatient setting?” Review Question as following: Population: Community-dwelling older adults aged ≥ 60 years old. Interventions/phenomena of interest: The interventions enhanced intrinsic capacities in older adults. We have eight domains in the intrinsic capacity including locomotor function, vitality, cognitive function, mood, hearing impairment, visual impairment, sleep, and continence. Outcomes: The improvement of intrinsic capacity depends on measurement tools with reliability and validity. Study design: Umbrella Review. Condition being studied: This review would aim to describe and synthesise the existing evidence of interventions maximising and/or enhancing the intrinsic capacity of older adults. In the end, this review will provide an effective evidence synthesis for the development of interventions to older adults in the community.

The overall goal of the research was to understand the processes involved in the development of woolliness in peaches and nectarines. Four specific hypotheses were proposed and in the course of the research evidence was gathered t support two of them and to not support two others. The hypotheses and a summary of the evidence are outlined below. 1. That woolliness arises from an imbalance between the activities of the cell wall pectin degrading enzymes. Using 'Flavortop' nectarines and 'Hermoza' peaches as model systems, storage regimes were manipulated to induce or prevent woolliness. The expression (mRNA abundance), protein content (Western blotting), and activity of polygalacturonase (PG) and pectin esterase (PE) were followed. Expression of the enzymes was not different, but activity and the ratio between PG and PE activities were quite different in fruits developing woolliness or ripening normally. This was also examined by looking at the substrate, the pectin moiety of the cell wall, and i woolly fruit there were more high molecular weight pectins with regions of non-methylated galacturonic acid residues. Taking an in vitro approach it was found a) that PE activity was stable at 0oC while PG activity decreased; b) incubating the calcium pectate fraction of the cell wall with PE extracted from peaches caused the polymers to form a gel characteristic of the visual woolly symptoms in peaches. 2. That continued cell wall synthesis occurs during storage and contributes to structural changes i cell walls and improper dissolution and softening after storage. We tried to adapt our technique of adding 13C-glucose to fruit discs, which was used successfully to follow cell wall synthesis during tomato ripening. However, the difference in sugar content between the two fruits (4% in tomato and 12% in peach) meant that the 13C-glucose was much more diluted within the general metabolite pool. We were unable to see any cell wall synthesis which meant that either the dilution factor was too great, or that synthesis was not occurring. 3. That controlled atmosphere (CA) prevents woolliness by lowering all enzyme activities. CA was found to greatly reduce mRNA abundance of the cell wall enzymes compared to regular air storage. However, their synthesis and activity recovered during ripening after CA storage and did not after regular air storage. Therefore, CA prevented the inhibition of enzyme activation found in regular air storage. 4. That changes in cell wall turgor and membrane function are important events in the development of woolliness. Using a micro pressure probe, turgor was measured in cells of individual 'O'Henry' and 'CalRed' peaches which were woolly or healthy. The relationship between firmness and turgor was the same in both fruit conditions. These data indicate that the development and expression of woolliness are not associated with differences in membrane function, at least with regard to the factors that determine cell turgor pressure. In addition, during the period of the grant additional areas were explored. Encoglucanase, and enzyme metabolizing hemicellulose, was found to be highly expressed air stored, but not in unstored or CA stored fruit. Activity gels showed higher activity in air stored fruit as well. This is the first indication that other components of the cell wall may be involved in woolliness. The role of ethylene in woolliness development was also investigated at it was found a) that woolly fruits had decreased ability to produce ethylene, b) storing fruits in the presence of ethylene delayed the appearance of woolliness. This latter finding has implication for an inexpensive strategy for storing peaches and nectarines.

The objectives of this project were to develop procedures and models, based on neural networks, for quality sorting of agricultural produce. Two research teams, one in Purdue University and the other in Israel, coordinated their research efforts on different aspects of each objective utilizing both melons and tomatoes as case studies. At Purdue: An expert system was developed to measure variances in human grading. Data were acquired from eight sensors: vision, two firmness sensors (destructive and nondestructive), chlorophyll from fluorescence, color sensor, electronic sniffer for odor detection, refractometer and a scale (mass). Data were analyzed and provided input for five classification models. Chlorophyll from fluorescence was found to give the best estimation for ripeness stage while the combination of machine vision and firmness from impact performed best for quality sorting. A new algorithm was developed to estimate and minimize training size for supervised classification. A new criteria was established to choose a training set such that a recurrent auto-associative memory neural network is stabilized. Moreover, this method provides for rapid and accurate updating of the classifier over growing seasons, production environments and cultivars. Different classification approaches (parametric and non-parametric) for grading were examined. Statistical methods were found to be as accurate as neural networks in grading. Classification models by voting did not enhance the classification significantly. A hybrid model that incorporated heuristic rules and either a numerical classifier or neural network was found to be superior in classification accuracy with half the required processing of solely the numerical classifier or neural network. In Israel: A multi-sensing approach utilizing non-destructive sensors was developed. Shape, color, stem identification, surface defects and bruises were measured using a color image processing system. Flavor parameters (sugar, acidity, volatiles) and ripeness were measured using a near-infrared system and an electronic sniffer. Mechanical properties were measured using three sensors: drop impact, resonance frequency and cyclic deformation. Classification algorithms for quality sorting of fruit based on multi-sensory data were developed and implemented. The algorithms included a dynamic artificial neural network, a back propagation neural network and multiple linear regression. Results indicated that classification based on multiple sensors may be applied in real-time sorting and can improve overall classification. Advanced image processing algorithms were developed for shape determination, bruise and stem identification and general color and color homogeneity. An unsupervised method was developed to extract necessary vision features. The primary advantage of the algorithms developed is their ability to learn to determine the visual quality of almost any fruit or vegetable with no need for specific modification and no a-priori knowledge. Moreover, since there is no assumption as to the type of blemish to be characterized, the algorithm is capable of distinguishing between stems and bruises. This enables sorting of fruit without knowing the fruits' orientation. A new algorithm for on-line clustering of data was developed. The algorithm's adaptability is designed to overcome some of the difficulties encountered when incrementally clustering sparse data and preserves information even with memory constraints. Large quantities of data (many images) of high dimensionality (due to multiple sensors) and new information arriving incrementally (a function of the temporal dynamics of any natural process) can now be processed. Furhermore, since the learning is done on-line, it can be implemented in real-time. The methodology developed was tested to determine external quality of tomatoes based on visual information. An improved model for color sorting which is stable and does not require recalibration for each season was developed for color determination. Excellent classification results were obtained for both color and firmness classification. Results indicted that maturity classification can be obtained using a drop-impact and a vision sensor in order to predict the storability and marketing of harvested fruits. In conclusion: We have been able to define quantitatively the critical parameters in the quality sorting and grading of both fresh market cantaloupes and tomatoes. We have been able to accomplish this using nondestructive measurements and in a manner consistent with expert human grading and in accordance with market acceptance. This research constructed and used large databases of both commodities, for comparative evaluation and optimization of expert system, statistical and/or neural network models. The models developed in this research were successfully tested, and should be applicable to a wide range of other fruits and vegetables. These findings are valuable for the development of on-line grading and sorting of agricultural produce through the incorporation of multiple measurement inputs that rapidly define quality in an automated manner, and in a manner consistent with the human graders and inspectors.