Visual probing : cognitive framework for explaining self-supervised image representations

Recently introduced self-supervised methods for image representation learning provide on par or superior results to their fully supervised competitors, yet the corresponding efforts to explain the self-supervised approaches lag behind. Motivated by this observation, we introduce a novel visual probing framework for explaining the self-supervised models by leveraging probing tasks employed previously in natural language processing. The probing tasks require knowledge about semantic relationships between image parts. Hence, we propose a systematic approach to obtain analogs of natural language in vision, such as visual words, context, and taxonomy. Our proposal is grounded in Marr’s computational theory of vision and concerns features like textures, shapes, and lines. We show the effectiveness and applicability of those analogs in the context of explaining self-supervised representations. Our key findings emphasize that relations between language and vision can serve as an effective yet intuitive tool for discovering how machine learning models work, independently of data modality. Our work opens a plethora of research pathways towards more explainable and transparent AI

Task-dependent fractal patterns of information processing in working memory

We applied detrended fluctuation analysis, power spectral density, and eigenanalysis of detrended cross-correlations to investigate fMRI data representing a diurnal variation of working memory in four visual tasks: two verbal and two nonverbal. We show that the degree of fractal scaling is regionally dependent on the engagement in cognitive tasks. A particularly apparent difference was found between memorisation in verbal and nonverbal tasks. Furthermore, the detrended cross-correlations between brain areas were predominantly indicative of differences between resting state and other tasks, between memorisation and retrieval, and between verbal and nonverbal tasks. The fractal and spectral analyses presented in our study are consistent with previous research related to visuospatial and verbal information processing, working memory (encoding and retrieval), and executive functions, but they were found to be more sensitive than Pearson correlations and showed the potential to obtain other subtler results. We conclude that regionally dependent cognitive task engagement can be distinguished based on the fractal characteristics of BOLD signals and their detrended cross-correlation structure

Visual Probing: Cognitive Framework for Explaining Self-Supervised Image Representations

Recently introduced self-supervised methods for image representation learning provide on par or superior results to their fully supervised competitors, yet the corresponding efforts to explain the self-supervised approaches lag behind. Motivated by this observation, we introduce a novel visual probing framework for explaining the self-supervised models by leveraging probing tasks employed previously in natural language processing. The probing tasks require knowledge about semantic relationships between image parts. Hence, we propose a systematic approach to obtain analogs of natural language in vision, such as visual words, context, and taxonomy. Our proposal is grounded in Marr's computational theory of vision and concerns features like textures, shapes, and lines. We show the effectiveness and applicability of those analogs in the context of explaining self-supervised representations. Our key findings emphasize that relations between language and vision can serve as an effective yet intuitive tool for discovering how machine learning models work, independently of data modality. Our work opens a plethora of research pathways towards more explainable and transparent AI

Non-linear Functional Brain Co-activations in Short-Term Memory Distortion Tasks

Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 ± 3.56 y.o.) performed in MRscanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects’ responses were modeled with a general linear model, which includes as a predictor the nonlinear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.Fil: Ceglarek, Anna. Jagiellonian University; PoloniaFil: Ochab, Jeremi K.. Jagiellonian University; PoloniaFil: Cifre, Ignacio. Universitat Ramon Llull; EspañaFil: Fafrowicz, Magdalena. Jagiellonian University; PoloniaFil: Sikora Wachowicz, Barbara. Jagiellonian University; PoloniaFil: Lewandowska, Koryna. Jagiellonian University; PoloniaFil: Bohaterewicz, Bartosz. Jagiellonian University; PoloniaFil: Marek, Tadeusz. Jagiellonian University; PoloniaFil: Chialvo, Dante Renato. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Físicas. - Universidad Nacional de San Martín. Instituto de Ciencias Físicas; Argentin

Beyond the low frequency fluctuations : morning and evening differences in human brain

Human performance, alertness, and most biological functions express rhythmic fluctuations across a 24-h-period. This phenomenon is believed to originate from differences in both circadian and homeostatic sleep-wake regulatory processes. Interactions between these processes result in time-of-day modulations of behavioral performance as well as brain activity patterns. Although the basic mechanism of the 24-h clock is conserved across evolution, there are interindividual differences in the timing of sleep-wake cycles, subjective alertness and functioning throughout the day. The study of circadian typology differences has increased during the last few years, especially research on extreme chronotypes, which provide a unique way to investigate the effects of sleep-wake regulation on cerebral mechanisms. Using functional magnetic resonance imaging (fMRI), we assessed the influence of chronotype and time-of-day on resting-state functional connectivity. Twenty-nine extreme morning- and 34 evening-type participants underwent two fMRI sessions: about 1 h after wake-up time (morning) and about 10 h after wake-up time (evening), scheduled according to their declared habitual sleep-wake pattern on a regular working day. Analysis of obtained neuroimaging data disclosed only an effect of time of day on resting-state functional connectivity; there were different patterns of functional connectivity between morning (MS) and evening (ES) sessions. The results of our study showed no differences between extreme morning-type and evening-type individuals. We demonstrate that circadian and homeostatic influences on the resting-state functional connectivity have a universal character, unaffected by circadian typology

Identifying diurnal variability of brain connectivity patterns using graph theory

Significant differences exist in human brain functions affected by time of day and by people’s diurnal preferences (chronotypes) that are rarely considered in brain studies. In the current study, using network neuroscience and resting-state functional MRI (rs-fMRI) data, we examined the effect of both time of day and the individual’s chronotype on whole-brain network organization. In this regard, 62 participants (39 women; mean age: 23.97 ± 3.26 years; half morning- versus half evening-type) were scanned about 1 and 10 h after wake-up time for morning and evening sessions, respectively. We found evidence for a time-of-day effect on connectivity profiles but not for the effect of chronotype. Compared with the morning session, we found relatively higher small-worldness (an index that represents more efficient network organization) in the evening session, which suggests the dominance of sleep inertia over the circadian and homeostatic processes in the first hours after waking. Furthermore, local graph measures were changed, predominantly across the left hemisphere, in areas such as the precentral gyrus, putamen, inferior frontal gyrus (orbital part), inferior temporal gyrus, as well as the bilateral cerebellum. These findings show the variability of the functional neural network architecture during the day and improve our understanding of the role of time of day in resting-state functional networks

Tendencja do podejmowania decyzji w sposób liberalny/konserwatywny a rozpoznawanie bodźców w zadaniach angażujących pamięć roboczą : perspektywa neurokognitywistyczna

Ze względu na ciągłe przenikanie się procesów decyzyjnych i pamięciowych w funkcjonowaniu poznawczym, ważnym wydaje się być pytanie o mechanizmy tej interakcji - również z perspektywy badań nad innymi procesami poznawczymi. W niniejszej pracy doktorskiej poruszony został problem wpływu nastawienia decyzyjnego (liberalnego lub konserwatywnego) na proces rozpoznawania bodźców, których reprezentacje utrzymywane są w magazynie pamięci operacyjnej. Na rozprawę składają się dwa spójne tematycznie opublikowane artykuły naukowe, których problematyka obejmuje zagadnienia z zakresu psychologii i neuronauki poznawczej, chronopsychologii i psychofizjologii. W obydwu zaprezentowanych eksperymentach wykorzystano zmodyfikowane wersje paradygmatu Deese-Roediger-McDermott, przeznaczonego do badania zniekształceń pamięci krótkotrwałej. Do określenia nastawienia decyzyjnego wykorzystano criterion - wskaźnik zdefiniowany przez teorię detekcji sygnałów. Analiza danych uzyskanych podczas pierwszego z badań miała na celu ustalenie czy nastawienie decyzyjne i skuteczność w różnicowaniu bodźców zmienia się wraz z porą dnia, wpływając na poziom wykonania zadań angażujących pamięć roboczą. Wyniki wykazały, że wieczorem w porównaniu do pory porannej badani częściej prezentowali liberalną strategię odpowiedzi. W zestawieniu z literaturą wskazującą na związek między nastawieniem decyzyjnym a aktywnością miejsca sinawego sugeruje to, że dobowe fluktuacje w poziomie noradrenaliny mogą przynajmniej częściowo wpływać na proces rozpoznawania bodźców. Przeprowadzenie drugiego z eksperymentów z wykorzystaniem techniki eye trackingu pozwoliło na określenie zależności między zmianami w szerokości źrenicy, nastawieniem decyzyjnym a typem reakcji (znany/nowy bodziec). Gdy nadchodząca reakcja była przeciwna do nastawienia decyzyjnego, źrenica była większa, przyrost jej wielkości wolniejszy, a czas reakcji dłuższy. Ponieważ zmiany w szerokości źrenicy są łączone ze zmianami w aktywności miejsca sinawego, wynik ten ponownie wskazuje na wpływ noradrenaliny na poziom wykonania zadań angażujących pamięć roboczą. Podsumowując, wyniki uzyskane w obydwu eksperymentach sugerują, że noradrenergiczny układ neuromodulacyjny wpływa na kształtowanie się nastawienia decyzyjnego podczas identyfikowania bodźców. Co ważne, do tej pory niewiele doniesień naukowych traktowało o wpływie noradrenaliny na proces rozpoznawania. W związku z tym przedstawione rezultaty wskazują nowy kierunek w badaniach nad rolą neuromodulacji w funkcjonowaniu poznawczym.Due to the continuous permeation of decision and memory processes in everyday cognitive functioning, the question about the mechanisms underlying their interaction seems to be of high importance - also from the perspective of research concerning other cognitive processes. This work discusses how response bias, liberal or conservative, impacts the ability to recognize stimuli when their representations are held in working memory. The thesis consists of two thematically consistent published research papers that deal with the issues from the fields of cognitive psychology and neuroscience, chronopsychology and psychophysiology. In both studies, modified versions of the Deese-Roediger-McDermott paradigm in a variant dedicated to study short-term memory distortions, were used. The criterion, a measurement established by the signal detection theory, was calculated to determine the response bias. Data analysis from the first study was aimed at determining whether decision bias and effectiveness in differentiating the stimuli change with the time-of-day, and as a consequence affect the performance in working memory tasks. The results have shown that participants were more likely to demonstrate more liberal response strategy in the evening, rather than in the morning. This, together with the previous literature pointing to the involvement of the locus coeruleus in response bias, may indicate that daily variations of the norepinephrine release impact, to some extent, the formation of recognition decisions. The second experiment, conducted with the use of the eye tracking technique, allowed to determine the relationship between changes in pupil dilation, decision bias and type of reaction (old/new item). When participants’ decision about the upcoming stimulus was not in line with their response bias, there was an increase in their pupil dilation, the pupil slope was gentler, and the response times were longer. As pupil dilation has been shown to be linked with the norepinephrine release, such findings indicate once more, that cognitive performance in working memory tasks may, at least partially, be linked with the locus coeruleus activity. Taken together, the results obtained from both of those experiments suggest that the noradrenergic neuromodulatory system may be crucial for the shaping of the decision bias during the identification of stimuli. As the role of the norepinephrine in recognition memory remains underexplored, reported findings set a novel direction in research on the role of neuromodulation in cognitive functioning

Richard Florida, Narodziny klasy kreatywnej oraz jej wpływ na przeobrażenia w charakterze pracy, wypoczynku, społeczeństwa i życia codziennego – recenzja książki

Richard Florida, 2010, Narodziny klasy kreatywnej: oraz jej wpływ na przeobrażenia w charakterze pracy, wypoczynku społeczeństwa i życia codziennego, tłum. T. Krzyżanowski, M. Penkala, Warszawa: Narodowe Centrum Kultury, 414