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Animal Cognition Nov 2023Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there... (Review)
Review
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
Topics: Animals; Photoreceptor Cells; Eye; Light
PubMed: 37650997
DOI: 10.1007/s10071-023-01818-6 -
Cephalalgia : An International Journal... Nov 2019To review clinical and pre-clinical evidence supporting the role of visual pathways, from the eye to the cortex, in the development of photophobia in headache disorders. (Review)
Review
OBJECTIVE
To review clinical and pre-clinical evidence supporting the role of visual pathways, from the eye to the cortex, in the development of photophobia in headache disorders.
BACKGROUND
Photophobia is a poorly understood light-induced phenomenon that emerges in a variety of neurological and ophthalmological conditions. Over the years, multiple mechanisms have been proposed to explain its causes; however, scarce research and lack of systematic assessment of photophobia in patients has made the search for answers quite challenging. In the field of headaches, significant progress has been made recently on how specific visual networks contribute to photophobia features such as light-induced intensification of headache, increased perception of brightness and visual discomfort, which are frequently experienced by migraineurs. Such progress improved our understanding of the phenomenon and points to abnormal processing of light by both cone/rod-mediated image-forming and melanopsin-mediated non-image-forming visual pathways, and the consequential transfer of photic signals to multiple brain regions involved in sensory, autonomic and emotional regulation.
CONCLUSION
Photophobia phenotype is diverse, and the relative contribution of visual, trigeminal and autonomic systems may depend on the disease it emerges from. In migraine, photophobia could result from photic activation of retina-driven pathways involved in the regulation of homeostasis, making its association with headache more complex than previously thought.
Topics: Animals; Blindness; Brain Stem; Color; Headache; Humans; Light; Mesencephalon; Mice; Migraine Disorders; Photic Stimulation; Photophobia; Retinal Ganglion Cells; Retinal Rod Photoreceptor Cells; Rod Opsins; Somatosensory Cortex; Thalamus; Visual Pathways
PubMed: 29940781
DOI: 10.1177/0333102418784750 -
Aging Dec 2021
Topics: Aging; Circadian Rhythm; Humans; Photophobia; Sleep
PubMed: 34962893
DOI: 10.18632/aging.203806 -
Cephalalgia : An International Journal... Nov 2019The clinical picture, but also neuroimaging findings, suggested the brainstem and midbrain structures as possible driving or generating structures in migraine. (Review)
Review
BACKGROUND
The clinical picture, but also neuroimaging findings, suggested the brainstem and midbrain structures as possible driving or generating structures in migraine.
FINDINGS
This has been intensely discussed in the last decades and the advent of modern imaging studies refined the involvement of rostral parts of the pons in acute migraine attacks, but more importantly suggested a predominant role of the hypothalamus and alterations in hypothalamic functional connectivity shortly before the beginning of migraine headaches. This was shown in the NO-triggered and also in the preictal stage of native human migraine attacks. Another headache type that is clinically even more suggestive of hypothalamic involvement is cluster headache, and indeed a structure in close proximity to the hypothalamus has been identified to play a crucial role in attack generation.
CONCLUSION
It is very likely that spontaneous oscillations of complex networks involving the hypothalamus, brainstem, and dopaminergic networks lead to changes in susceptibility thresholds that ultimately start but also terminate headache attacks. We will review clinical and neuroscience evidence that puts the hypothalamus in the center of scientific attention when attack generation is discussed.
Topics: Autonomic Nervous System; Brain Stem; Craving; Dopamine; Emotions; Endocrine System; Headache; Humans; Hypothalamus; Migraine Disorders; Nitric Oxide; Nociception; Pain Perception; Photophobia; Prodromal Symptoms
PubMed: 31466456
DOI: 10.1177/0333102419867280 -
Cephalalgia : An International Journal... Aug 2023Clinical trials on anti-calcitonin gene-related peptide monoclonal antibodies poorly investigated their impact on migraine accompanying symptoms.
BACKGROUND
Clinical trials on anti-calcitonin gene-related peptide monoclonal antibodies poorly investigated their impact on migraine accompanying symptoms.
OBJECTIVE
To evaluate the impact of basal accompanying symptoms on anti-CGRP monoclonal antibodies treatment response and their evolution after six months of treatment in migraine patients.
METHODS
Patients with migraine diagnosis seen in the Headache Clinic and treated with erenumab, galcanezumab or fremanezumab were prospectively recruited. They completed a daily eDiary which provided data on headache frequency and the following accompanying symptoms of each day: photophobia, phonophobia, nausea, dizziness, and aura. Patients were classified as responders or non-responders based on 50% or greater reduction in headache days per month at month 6 (≥50% response rate). Accompanying symptoms ratios based on headache days per month were assessed per patient at baseline and after three and six months. Comparisons for basal characteristics, basal accompanying symptoms ratios and their evolution after six months between responders and non-responders were performed.
RESULTS
One hundred and fifty-eight patients were included, 44% (69/158) showed ≥50% response rate after six months. A significant reduction in headache days per month in both groups was found at month 6 (-9.4 days/month in ≥50% response rate group; p < 0.001, -2.2 days/month in <50% response rate group; p = 0.004). Additionally, significant decreases in photophobia (-19.5%, p < 0.001), phonophobia (-12.1%, p = 0.010) and aura ratios (-25.1%, p = 0.008) were found in ≥50% response rate group. No statistically significant reductions were found in nausea and dizziness in any group since their reduction was correlated with the decrease in headache days per month. Higher photophobia ratios at baseline were predictive of an increased response between months 3 and 6 (Incidence Risk Ratio = 0.928, p = 0.040).
CONCLUSIONS
The days per month with photophobia, phonophobia and aura decreased at a higher rate than headache days per month after six months in the ≥50% response group. Higher photophobia ratios were associated with higher response rates between three and six months. It could indicate an involvement of peripheral CGRP in photophobia as well as a central modulation of migraine through these treatments which mainly act on the periphery.
Topics: Humans; Antibodies, Monoclonal; Dizziness; Headache; Hyperacusis; Migraine Disorders; Nausea; Photophobia; Treatment Outcome
PubMed: 37555331
DOI: 10.1177/03331024231177636 -
Headache Apr 2015Photophobia is a debilitating feature of many headache disorders. (Review)
Review
BACKGROUND
Photophobia is a debilitating feature of many headache disorders.
OVERVIEW
Clinical and preclinical research has identified several potential pathways involved in enhanced light sensitivity. Some of these structures include trigeminal afferents in the eye, second-order neurons in the trigeminal nucleus caudalis, third-order neurons in the posterior thalamus, modulatory neurons in the hypothalamus, and fourth-order neurons in the visual and somatosensory cortices. It is unclear to what degree each site plays a role in establishing the different temporal patterns of photophobia across different disorders. Peptides such as calcitonin gene-related peptide and pituitary adenylate cyclase-activating polypeptide may play a role in photophobia at multiple levels of the visual and trigeminal pathways.
CONCLUSION
While our understanding of photophobia has greatly improved in the last decade, there are still unanswered questions. These answers will help us develop new therapies to provide relief to patients with primary headache disorders.
Topics: Headache Disorders, Primary; Humans; Photophobia; Trigeminal Nerve; Visual Pathways
PubMed: 25790126
DOI: 10.1111/head.12532 -
PloS One 2022Cataract surgery impinges on the spatial properties and wavelength distribution of retinal images, which changes the degree of light-induced visual...
Cataract surgery impinges on the spatial properties and wavelength distribution of retinal images, which changes the degree of light-induced visual discomfort/photophobia. However, no study has analyzed the alteration in photophobia before and after cataract surgery or the association between retinal spatial property and photophobia. Here, we measured the higher-order aberrations (HOAs) of the entire eye and the subjective photophobia score. This study investigated 71 eyes in 71 patients who received conventional cataract surgery. Scaling of photophobia was based on the following grading system: when the patient is outdoor on a sunny day, score of 0 and 10 points were assigned to the absence of photophobia and the presence of severe photophobia prevents eye-opening, respectively. We decomposed wavefront errors using Zernike polynomials for a 3-mm pupil diameter and analyzed the association between photophobia scores and HOAs with Spearman's rank sum correlation (rs). We classified patients into two groups: photophobia (PP) unconcerned included patients who selected 0 both preoperatively or postoperatively and PP concerned included the remaining patients. After cataract surgery, photophobia scores increased, remained unchanged (stable), and decreased in 3, 41, and 27 cases, respectively. In the stable group, 35 of 41 cases belonged to PP unconcerned. In PP concerned, there were significant correlations between photophobia score and postoperative root-mean-square values of total HOAs (rs = 0.52, p = 0.002), total coma (rs = 0.52, p = 0.002), total trefoil (rs = 0.47, p = 0.006), and third-order group (rs = 0.53, p = 0.002). In contrast, there was no significant correlation between photophobia scores and preoperative HOAs. Our results suggest that the spatial properties of retinal image modified by HOAs may affect the degree of photophobia. Scattering light due to cataracts could contribute to photophobia more than HOAs, which may mask the effect of HOAs for photophobia preoperatively.
Topics: Cataract; Eye; Humans; Photophobia; Vision Disorders
PubMed: 36107829
DOI: 10.1371/journal.pone.0274705 -
Frontiers in Neurology 2022To investigate the auditory features of patients with vestibular migraine (VM) and to analyze the possible relevant factors of hearing loss.
OBJECTIVES
To investigate the auditory features of patients with vestibular migraine (VM) and to analyze the possible relevant factors of hearing loss.
METHODS
A total of 166 patients with VM were enrolled. Demographic variables, age of onset, disease course, distribution of vestibular attacks, characteristics of hearing loss, and the coexistence of related disorders, such as visual aura, familial history, motion sickness, nausea, headache, photophobia, otalgia, tinnitus, aural fullness, and phonophobia, were analyzed and compared.
RESULTS
Patients with VM can manifest otalgia (8.4%), tinnitus (51.8%), aural fullness (41%), and phonophobia (31.9%). Of 166 patients, the prevalence of VMw was 21.1% ( = 35). Patients with VMw mainly manifested mild and easily reversible low-frequency hearing loss. The proportions of tinnitus and aural fullness were significantly larger in patients with VMw than that in patients with VMo ( < 0.05). The duration of vestibular symptoms was significantly shorter in patients with VMw ( < 0.05). However, the age of onset, disease course, gender, frequency of vestibular attacks, the coexistence of visual aura, familial history, motion sickness, nausea, headache, photophobia, otalgia, and phonophobia had no significant difference between the two groups.
CONCLUSION
Auditory symptoms were common in patients with VM. The hearing loss of VM was characterized by a mild and easily reversible low-frequency hearing loss, accompanied by higher proportions of tinnitus and aural fullness, and a shorter duration of vestibular symptoms compared with patients with VMo.
PubMed: 35911900
DOI: 10.3389/fneur.2022.944001 -
Frontiers in Neurology 2022Calcitonin gene-related peptide (CGRP) plays a pivotal role in migraine physiology, not only regarding migraine pain but also associated symptoms such as photophobia....
BACKGROUND
Calcitonin gene-related peptide (CGRP) plays a pivotal role in migraine physiology, not only regarding migraine pain but also associated symptoms such as photophobia. The aim of the present study was to assess monoclonal antibodies targeting CGRP efficacy not only in terms of headache and migraine frequency and disability but also in reducing ictal photophobia.
MATERIAL AND METHODS
This is a retrospective observational study, conducted at the Headache Center-ASST Spedali Civili Brescia. All patients in monthly treatment with galcanezumab with at least a 6-month follow-up in September 2022 with reported severe photophobia during migraine attacks were included. Data regarding headache frequency, analgesics consumption, and migraine disability were collected quarterly. Moreover, patients were asked the following information regarding photophobia: (1) whether they noticed an improvement in photophobia during migraine attacks since galcanezumab introduction; (2) the degree of photophobia improvement (low, moderate, and high); and (3) timing photophobia improvement.
RESULTS
Forty-seven patients were enrolled in the present study as they met the inclusion criteria. Seventeen patients had a diagnosis of high-frequency episodic migraine and 30 of chronic migraine. From baseline to T3 and T6, a significant improvement in terms of headache days (19.2 ± 7.6 vs. 8.6 ± 6.8 vs. 7.7 ± 5.7; < 0.0001), migraine days (10.4 ± 6.7 vs. 2.9 ± 4.3 vs. 3.6 ± 2.8; < 0.0001), analgesics consumption (25.1 ± 28.2 vs. 7.6 ± 7.5 vs. 7.6 ± 8.1; < 0.0001), MIDAS score (82.1 ± 48.4 vs. 21.6 ± 17.6 vs. 18.1 ± 20.5; < 0.0001), and HIT-6 score (66.2 ± 6.2 vs. 57.2 ± 8.6 vs. 56.6 ± 7.6; < 0.0001) was found. Thirty-two patients (68.1%) reported a significant improvement in ictal photophobia, with over half of the patients reporting it within the first month of treatment. Photophobia improvement was more frequent in patients with episodic migraine ( = 0.02) and triptans responders ( = 0.03).
CONCLUSIONS
The present study confirms previous reports regarding galcanezumab efficacy beyond migraine frequency. In particular, over 60% of patients, in our cohort, documented a significant improvement also in reducing ictal photophobia. This improvement was, in most patients, moderate to high, and within the first 6 months of treatment, regardless of the clinical response on migraine frequency.
PubMed: 36742057
DOI: 10.3389/fneur.2022.1088036