Quantifying sensory thresholds along the migraine cycle: An exploratory longitudinal study.

BACKGROUND: To date, a number of studies on migraine have cross-sectionally evaluated sensory sensitivity with aversion thresholds/scores along the migraine cycle, reporting a decreased tolerance to sensory stimuli in different sensory modalities. Our hypothesis was that patients with migraine would exhibit heightened sensitivity to sound, light, touch and smell on days where they reported greater headache intensity. METHODS: This is an exploratory, longitudinal study, carried out over the course of 27 days. Aversion thresholds or scores to sound, light, touch and smell were quantified in six patients with migraine (11.33 ± 6.53 headache days/month). RESULTS: Patients reported an increased sensitivity to light (padj = 0.0297), touch (padj = 0.0077), and smell (padj = 0.0201) on days with higher headache intensity. However, a greater sensitivity to sound on days with higher headache intensity was only reported when anxiety levels were high (padj = 1.4e-06). Interestingly, variable levels of tolerance to bothersome light over time can also influence the correlation between light sensitivity and headache intensity (padj = 1.4e-06). CONCLUSIONS: Based on the present findings, future longitudinal studies evaluating sensory threshold changes along the migraine cycle in patients with migraine should account for the increased tolerance to bothersome light over time as well as the effect of anxiety on auditory sensitivity.

Exploring sensory sensitivity, cortical excitability, and habituation in episodic migraine, as a function of age and disease severity, using the pattern-reversal task.

BACKGROUND: Migraine is a cyclic, neurosensory disorder characterized by recurrent headaches and altered sensory processing. The latter is manifested in hypersensitivity to visual stimuli, measured with questionnaires and sensory thresholds, as well as in abnormal cortical excitability and a lack of habituation, assessed with visual evoked potentials elicited by pattern-reversal stimulation. Here, the goal was to determine whether factors such as age and/or disease severity may exert a modulatory influence on sensory sensitivity, cortical excitability, and habituation. METHODS: Two similar experiments were carried out, the first comparing 24 young, episodic migraine patients and 28 healthy age- and gender-matched controls and the second 36 middle-aged, episodic migraine patients and 30 healthy age- and gender-matched controls. A neurologist confirmed the diagnoses. Migraine phases were obtained using eDiaries. Sensory sensitivity was assessed with the Sensory Perception Quotient and group comparisons were carried out. We obtained pattern-reversal visual evoked potentials and calculated the N1-P1 Peak-to-Peak amplitude. Two linear mixed-effects models were fitted to these data. The first model had Block (first block, last block) and Group (patients, controls) as fixed factors, whereas the second model had Trial (all trials) and Group as fixed factors. Participant was included as a random factor in both. N1-P1 first block amplitude was used to assess cortical excitability and habituation was defined as a decrease of N1-P1 amplitude across Blocks/Trials. Both experiments were performed interictally. RESULTS: The final samples consisted of 18 patients with episodic migraine and 27 headache-free controls (first experiment) and 19 patients and 29 controls (second experiment). In both experiments, patients reported increased visual hypersensitivity on the Sensory Perception Quotient as compared to controls. Regarding N1-P1 peak-to-peak data, there was no main effect of Group, indicating no differences in cortical excitability between groups. Finally, significant main effects of both Block and Trial were found indicating habituation in both groups, regardless of age and headache frequency. CONCLUSIONS: The results of this study yielded evidence for significant hypersensitivity in patients but no significant differences in either habituation or cortical excitability, as compared to headache-free controls. Although the alterations in patients may be less pronounced than originally anticipated they demonstrate the need for the definition and standardization of optimal methodological parameters.

Expressive recall and recognition as complementary measures to assess novel word learning ability in aphasia.

Novel word learning ability has been associated with language treatment outcomes in people with aphasia (PWA), and its assessment could inform prognosis and rehabilitation. We used a brief experimental task to examine novel word learning in PWA, determine the value of phonological cueing in assessing learning outcomes, and identify factors that modulate learning ability. Twelve PWA and nineteen healthy controls completed the task, and recall and recognition tests of learning ability. Most PWA showed comparable learning outcomes to those of the healthy controls. Learning assessed via expressive recall was more clearly evidenced with phonological cues. Better single word processing abilities and phonological short-term memory and higher integrity of the left inferior frontal gyrus were related to better learning performance. Brief learning tasks like this one are clinically feasible and hold promise as screening tools of verbal learning in PWA once validated and evaluated for their capacity to predict treatment outcomes.

Avoidance behaviour modulates but does not condition phonophobia in migraine.

BACKGROUND: Past studies do not account for avoidance behaviour in migraine as a potential confounder of phonophobia. OBJECTIVE: To analyse whether phonophobia is partially driven by avoidance behaviour when using the classic methodology (method of limits). METHODS: This is a case-control study where we tested phonophobia in a cohort of high-frequency/chronic migraine patients (15.5 ± 0.74 headache days/month) and non-headache controls. Auditory stimuli, delivered in both ears, were presented using three different paradigms: the method of limits, the method of constant stimuli, and the adaptive method. Participants were asked to report how bothersome each tone was until a sound aversion threshold was estimated for each method. RESULTS: In this study, we successfully replicate previously reported reduction in sound aversion threshold using three different methods in a group of 35 patients and 25 controls (p < 0.0001). Avoidance behaviour in migraine reduced sound aversion threshold in the method of limits (p = 0.0002) and the adaptive method (p < 0.0001) when compared to the method of constant stimuli. While thresholds in controls remained the same across methods (method of limits, p = 0.9877 and adaptive method, p = 1). CONCLUSION: Avoidance behaviour can exacerbate phonophobia. The current methodology to measure phonophobia needs to be revised.

The contribution of luminance and chromatic channels to color assimilation.

Color induction is the phenomenon where the physical and the perceived colors of an object differ owing to the color distribution and the spatial configuration of the surrounding objects. Previous works studying this phenomenon on the lsY MacLeod-Boynton color space, show that color assimilation is present only when the magnocellular pathway (i.e., the Y axis) is activated (i.e., when there are luminance differences). Concretely, the authors showed that the effect is mainly induced by the koniocellular pathway (s axis), but not by the parvocellular pathway (l axis), suggesting that when magnocellular pathway is activated it inhibits the koniocellular pathway. In the present work, we study whether parvo-, konio-, and magnocellular pathways may influence on each other through the color induction effect. Our results show that color assimilation does not depend on a chromatic-chromatic interaction, and that chromatic assimilation is driven by the interaction between luminance and chromatic channels (mainly the magno- and the koniocellular pathways). Our results also show that chromatic induction is greatly decreased when all three visual pathways are simultaneously activated, and that chromatic pathways could influence each other through the magnocellular (luminance) pathway. In addition, we observe that chromatic channels can influence the luminance channel, hence inducing a small brightness induction. All these results show that color induction is a highly complex process where interactions between the several visual pathways are yet unknown and should be studied in greater detail.

The impact of a digital platform on migraine patient-centered outcome research. Evaluation of midolordecabeza.org, a headache website in Spanish.

OBJECTIVE: This internet survey aimed to analyze the activity of midolordecabeza.org, a specialized website for headache stakeholders. BACKGROUND: eHealth tools, such as websites, can be educational for stakeholders of a specific disease, such as patients. This is particularly helpful in chronic disorders such as migraine. eHealth also enhances patient-centered outcome research. The website midolordecabeza.org has the stated aim of organizing key information on headache making it accessible and useful for all stakeholders, and, eventually promoting patient participation. METHODS: We analyzed Google Analytics (GA) data to study the web's activity, traffic source, geographical distribution of access, registered-user behavior, electronic device performance, and temporary references with greater web activity. RESULTS: From January 2015 until December 2020, the website registered 1,121,585 visitors, 1,775,953 sessions, and a total of 3,833,144 views with an average time per session of nearly 2 min. Higher data traffic has been registered in Spanish-speaking countries such as Spain (33.3%; 591,256/1,775,953), where Spain's regions with higher views were statistically significantly correlated with the nationwide migraine prevalence (ρ = 0.505; p = 0.039). In regard to social behavior, returning users were statistically significantly associated with being a woman (84.0%; 5696/6781), and they predominantly acceded from organic searches (50.6%; 3434/6781). When answering available open surveys, 72.5% (1827/2520) described their migraine as a disabling disease with high impact on their daily tasks and 64.4% (14,016/21,764) were unaware of what their headache diagnosis is. CONCLUSIONS: Spanish-speaking patients with migraine around the world increasingly visited the headache-specialized website midolordecabeza.org using different electronic devices, showing great interest in their disease. This website allowed them to get updated information on their disease, share clinical data with physicians, and finally express their concerns.

Chromatic Induction in Migraine.

The human visual system is not a colorimeter. The perceived colour of a region does not only depend on its colour spectrum, but also on the colour spectra and geometric arrangement of neighbouring regions, a phenomenon called chromatic induction. Chromatic induction is thought to be driven by lateral interactions: the activity of a central neuron is modified by stimuli outside its classical receptive field through excitatory-inhibitory mechanisms. As there is growing evidence of an excitation/inhibition imbalance in migraine, we compared chromatic induction in migraine and control groups. As hypothesised, we found a difference in the strength of induction between the two groups, with stronger induction effects in migraine. On the other hand, given the increased prevalence of visual phenomena in migraine with aura, we also hypothesised that the difference between migraine and control would be more important in migraine with aura than in migraine without aura. Our experiments did not support this hypothesis. Taken together, our results suggest a link between excitation/inhibition imbalance and increased induction effects.

Color induction in equiluminant flashed stimuli.

Color induction is the influence of the surrounding color (inducer) on the perceived color of a central region. There are two different types of color induction: color contrast (the color of the central region shifts away from that of the inducer) and color assimilation (the color shifts towards the color of the inducer). Several studies on these effects have used uniform and striped surrounds, reporting color contrast and color assimilation, respectively. Other authors [J. Vis.12(1), 22 (2012)1534-736210.1167/12.12.1] have studied color induction using flashed uniform surrounds, reporting that the contrast is higher for shorter flash duration. Extending their study, we present new psychophysical results using both flashed and static (i.e., non-flashed) equiluminant stimuli for both striped and uniform surrounds. Similarly to them, for uniform surround stimuli we observed color contrast, but we did not obtain the maximum contrast for the shortest (10 ms) flashed stimuli, but for 40 ms. We only observed this maximum contrast for red, green, and lime inducers, while for a purple inducer we obtained an asymptotic profile along the flash duration. For striped stimuli, we observed color assimilation only for the static (infinite flash duration) red-green surround inducers (red first inducer, green second inducer). For the other inducers' configurations, we observed color contrast or no induction. Since other studies showed that non-equiluminant striped static stimuli induce color assimilation, our results also suggest that luminance differences could be a key factor to induce it.

The effect of luminance differences on color assimilation.

The color appearance of a surface depends on the color of its surroundings (inducers). When the perceived color shifts towards that of the surroundings, the effect is called "color assimilation" and when it shifts away from the surroundings it is called "color contrast." There is also evidence that the phenomenon depends on the spatial configuration of the inducer, e.g., uniform surrounds tend to induce color contrast and striped surrounds tend to induce color assimilation. However, previous work found that striped surrounds under certain conditions do not induce color assimilation but induce color contrast (or do not induce anything at all), suggesting that luminance differences and high spatial frequencies could be key factors in color assimilation. Here we present a new psychophysical study of color assimilation where we assessed the contribution of luminance differences (between the target and its surround) present in striped stimuli. Our results show that luminance differences are key factors in color assimilation for stimuli varying along the s axis of MacLeod-Boynton color space, but not for stimuli varying along the l axis. This asymmetry suggests that koniocellular neural mechanisms responsible for color assimilation only contribute when there is a luminance difference, supporting the idea that mutual-inhibition has a major role in color induction.

Which tone-mapping operator is the best? A comparative study of perceptual quality.

Tone-mapping operators (TMOs) are designed to generate perceptually similar low-dynamic-range images from high-dynamic-range ones. We studied the performance of 15 TMOs in two psychophysical experiments where observers compared the digitally generated tone-mapped images to their corresponding physical scenes. All experiments were performed in a controlled environment, and the setups were designed to emphasize different image properties: in the first experiment we evaluated the local relationships among intensity levels, and in the second one we evaluated global visual appearance among physical scenes and tone-mapped images, which were presented side by side. We ranked the TMOs according to how well they reproduced the results obtained in the physical scene. Our results show that ranking position clearly depends on the adopted evaluation criteria, which implies that, in general, these tone-mapping algorithms consider either local or global image attributes but rarely both. Regarding the question of which TMO is the best, KimKautz ["Consistent tone reproduction," in Proceedings of Computer Graphics and Imaging (2008)] and Krawczyk ["Lightness perception in tone reproduction for high dynamic range images," in Proceedings of Eurographics (2005), p. 3] obtained the better results across the different experiments. We conclude that more thorough and standardized evaluation criteria are needed to study all the characteristics of TMOs, as there is ample room for improvement in future developments.