Ipsilateral Eye Research Articles

The effect of unilateral disruption of the centrifugal visual system on normal eye development in chicks raised under constant light conditions

The centrifugal visual system (CVS) comprises a visually driven isthmic feedback projection to the retina. While its function has remained elusive, we have previously shown that, under otherwise normal conditions, unilateral disconnection of centrifugal neurons in the chick affected eye development, inducing a reduced rate of axial elongation that resulted in a unilateral hyperopia in the eye contralateral to the lesion. Here, we further investigate the role of centrifugal neurons in ocular development in chicks reared in an abnormal visual environment, namely constant light. The baseline ocular phenotype of constant light-reared chicks (n = 8) with intact centrifugal neurons was assessed over a 3-week post-hatch time period and, subsequently, compared to chicks raised in normal diurnal lighting (n = 8). Lesions of the isthmo-optic tract or sham surgeries were performed in another seventeen chicks, all raised under constant light. Ocular phenotyping was performed over a 21-day postoperative period to assess changes in refractive state (streak retinoscopy) and ocular component dimensions (A-scan ultrasonography). A pathway-tracing paradigm was employed to quantify lesion success. Chicks raised in constant light conditions with an intact CVS developed shallower anterior chambers combined with elongated vitreous chambers relative to chicks raised in normal diurnal lighting. Seven days following surgery to disrupt centrifugal neurons, a significant positive correlation between refractive error asymmetry between the eyes and lesion success was evident, characterized by hyperopia in the eye contralateral to the lesion. By 21 days post-surgery, these contralateral eyes had become emmetropic, while ipsilateral eyes had developed relative axial hyperopia. Our results provide further support for the hypothesis that the centrifugal visual system can modulate eye development.

The local and referred pain patterns of the longus colli muscle

The longus colli muscle is a neck flexor believed to play an important role in pain originating in the neck region, including pain resulting from whiplash injuries. Despite the clinical importance attributed to it, the pain referral pattern of the longus colli has previously been described only in a small cohort of subjects. Here, we aim to delineate the pain referral pattern of the longus colli muscle. Thirty-five healthy volunteers underwent deep massage of the longus colli followed by dry needling of the muscle. The subjects depicted the distribution of the pain they experienced on a blank manikin. Their drawings were digitized and used to produce pain pattern histogram maps. The pain referral pattern during deep massage and needling of the longus colli was primarily local, with referral to the ipsilateral ear and lateral to the ipsilateral eye. Some subjects reported pain on the contralateral side of the neck.

Impairment of Brain Plasticity by Brain Inflammation

Abstract. The ability to learn and the ability to reshape brain circuits are regarded as some of the most remarkable and important features of the brain. This ability declines with age due to largely unknown reasons, and it also is altered following stroke. Brain aging is associated with a progressive increase of the levels of inflammatory cytokine in the brain. Likewise, stroke causes pronounced increases of inflammatory cytokines in the brain. Following stroke, plasticity of the cortical representation following sensory deprivation and visualized with [14C]-2-deoxyglucose autoradiography is impaired for several weeks. Likewise, plasticity of visual acuity induced by occlusion of the ipsilateral eye is impaired. Both forms of plasticity may be rescued by treatment with anti-inflammatory drugs. In contrast to this, ocular dominance plasticity which is also induced by visual occlusion is not rescued by this intervention, neither following stroke nor in aged brains. Antiinflammatory interventions may therefore be a useful tool to enhance brain plasticity following stroke, but need to be supplemented by additional strategies to enhance brain plasticity.

Changes in retinal nerve fiber layer thickness in patients with cerebral infarction: evidence of transneuronal retrograde degeneration.

We aimed to evaluate the thicknesses of the retinal nerve fiber layer (RNFL) in patients with cerebral infarction (CI) by using optical coherence tomography. This cross-sectional study evaluated 45 patients with CI (patient group) and 45 healthy subjects (control group). All subjects underwent a complete ophthalmic examination including optical coherence tomography. The average, temporal, nasal, inferior, and superior quadrant RNFL thicknesses and in each of 12 sectors around the optic nerve head were obtained. The side with the infarction was compared to the contralateral side among the patients with cerebral infarction, and their measurements were also compared to those of the control group. Patients who had CI only in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) were included in this study. Correlations between the RNFL thicknesses and infarction features were also evaluated. The mean age of the patients was 61.6±12.4years, and the mean age of the controls was 59.6±11.8years (p=0.65). Of the 45 patients with cerebral infarction, 35 (77.7%) had infarction in the MCA territory, 10 (22.2%) had infarction in the PCA territory and the mean duration of the disease was 20.2±29.1months. The average, superior, inferior, and nasal RNFL thicknesses were significantly thinner in both eyes of the patients with CI than in the eyes of the control group (p<0.05). The average and inferior RNFL thicknesses were significantly more affected in the ipsilateral eyes than in the contralateral eyes (p<0.031 and p<0.006, respectively). The amount of reduction in the RNFL thicknesses was not correlated with the infarction features. Significant thinning of the RNFL in patients with CI may result from transneuronal retrograde degeneration. Optical coherence tomography may provide useful information to confirm the process of trans-synaptic retrograde degeneration.

Macular Ganglion Cell Layer and Peripapillary Retinal Nerve Fibre Layer Thickness in Patients with Unilateral Posterior Cerebral Artery Ischaemic Lesion: An Optical Coherence Tomography Study

ABSTRACTThe purpose of this study is to evaluate the macular ganglion cell layer (GCL) and peripapillary retinal nerve fibre layer (RNFL) thickness in patients with unilateral posterior cerebral artery (PCA) ischaemic lesions using spectral-domain optical coherence tomography (SD-OCT). A prospective, case-control study of patients with unilateral PCA lesion was conducted in the neuro-ophthalmology clinic of Centro Hospitalar Lisboa Central. Macular and peripapillary SD-OCT scans were performed in both eyes of each patient. Twelve patients with PCA lesions (stroke group) and 12 healthy normal controls were included in this study. Peripapillary RNFL comparison between both eyes of the same subject in the stroke group found a thinning in the superior-temporal (p = 0.008) and inferior-temporal (p = 0.023) sectors of the ipsilateral eye and nasal sector (p = 0.003) of the contralateral eye. Macular GCL thickness comparison showed a reduction temporally in the ipsilateral eye (p = 0.004) and nasally in the contralateral eye (p = 0.002). Peripapillary RNFL thickness was significantly reduced in both eyes of patients with PCA compared with controls, affecting all sectors in the contralateral eye and predominantly temporal sectors in the ipsilateral eye. A statistically significant decrease in macular GCL thickness was found in both hemiretinas of both eyes of stroke patients when compared with controls (p < 0.05). This study shows that TRD may play a role in the physiopathology of lesions of the posterior visual pathway.

Radiation dose measurements during kilovoltage-cone beam computed tomography imaging in radiotherapy

The use of image guidance during radiotherapy for accurate localization and setup has become the standard care of practice in radiotherapy. This mostly involves the use of kilovoltage-cone beam computed tomography (kV-CBCT) for verification of patient setup on the first few days and on a weekly basis. Some protocols require this to be performed daily and also before and after the treatment. Though the radiation due to this kV-CBCT is small, the repeated use could deliver a dose that could increase the probability of the stochastic effect. The main purpose of this work is to measure radiation dose during image guidance with kV-CBCT. In this work, we have attempted to measure the dose during kV-CBCT for different sites both on a humanoid phantom and on patients undergoing image-guided radiotherapy with MOSFETs calibrated against an ion chamber. The dose measurement on patients during kV-CBCT resulted in mean doses of 0.19 and 0.3 cGy to the ipsilateral and contralateral eyes, 0.625 and 1.097 cGy to the surface of the ipsilateral and contralateral breasts, and 3.01 cGy to the surface of the pelvis. Radiation dose to the eye, breast, and the surface of the pelvis have been arrived at during CBCT. The doses measured on patients agreed closely with those measured on humanoid phantom and with published values.

O065. Drug-resistant chronic cluster headache successfully treated with supraorbital plus occipital nerve stimulation. A rare case report.

Chronic cluster headache (CCH) is a rare and extremely disabling headache syndrome with a recent clinical systematization of its clinical frame from the European Headache Federation [1]. We present a case of a young man affected by drug-resistant chronic CH (rCCH) who showed improvement after a two-time combined supraorbital and occipital nerve stimulation (S-ONS). The clinical improvement was still present at 6-month follow-up. A 37-year-old man (LB), with an 18-year history of episodic CH ab initio, was referred to our Regional Referral Headache Centre first, and then to the Pain Unit, because the headache had become chronic (CCH), and the patient suffered from daily cluster attacks (4-6/day). The patient became progressively unresponsive to prophylactic/acute therapies, including O2-therapy, verapamil up to 600 mg/ day, external vagus nerve stimulation, etc. The headache was strictly left-sided. The pain emerged at the left occipital region and migrated towards the ipsilateral eye, becoming throbbing and increasing up to 10/10. It remained fixed within the orbital area between 45 and 80 minutes, accompanied by concurrent, ipsilateral conjunctival injection and tearing. Brain magnetic resonance imaging excluded any underlying lesions. Sumatriptan 6 mg i.m. maintained over time its efficacy, but during the last year the risk of serious cardiac side effects suggested to look for an alternative treatment to reduce its harmful overuse. After careful psychological assessment, the patient was considered eligible for occipital nerve stimulation (ONS) trial. Three weeks later he was implanted with a >50%/<85% reduction of attack number and intensity of pain. Unfortunately, three months after surgery, the patient complained of a reappearance of his usual severe CH attack (VAS 10), periorbitally located. We decided to implant an additional electrocatheter stimulating bilaterally the supraorbita ln erves (SON). At six-month follow-up the patient referred suffering of 1 attack a week, of mild/moderate intensity, not altering his overall improved quality of life. ONS was efficient in most of the rCCH patients reported in the literature with low complication rates [2]. In our patient, the ONS was partially effective in relieving symptoms, achieving excellent pain relief only when supraorbital stimulation (SON) was associated [Fig. 1]. Evidence from future RCTs should support this approach in order to give guidelines for a multimodal approach to similar rare/unusual case reports. Written informed consent to publication was obtained from the patient(s).

The deceptively simple N170 hides a complex diagnostic coding mechanism involving visual feature transfer across hemispheres.

Abstract A key to understanding visual cognition is to determine when and how brain responses are sensitive to the specific visual information underlying categorization behavior. We know that the N170 is the first brain response coding such diagnostic information (Schyns et al., Current Biology 2007), as recently shown in Rousselet et al.'s experiment (Journal of Vision 2014). Using Bubbles (Gosselin & Schyns, Vision Research 2001), we found that the eyes are diagnostic for face detection and are coded in latency and amplitude modulations of the N170. Here, with new analyses we show that diagnostic coding of the eyes in the N170 involves cross-hemispheric transfer. We proceed in three steps. First, we show that the eye contralateral to the recording electrode (i.e. Occipito-Temporal Left, or Right, OTL, OTR) modulates the N170 latencies, whereas the ipsilateral eye modulates the later N170 amplitudes. Second, we show that single-trial N170 latencies and amplitudes fully account for all the coding of the eye that can be extracted from the EEG signal, at any time point. Finally, we show an important effect of the temporal ordering of the left and right N170s (on OTL and OTR) on coding of the eyes. Specifically, an earlier N170 on OTL (initially coding the right eye) has a strong effect on the later coding of the right eye on OTR (initially coding the left eye), suggesting causal transfer of the right eye across hemispheres. To summarize, in a face detection task where both eyes are diagnostic, the N170 ERP initially codes the contralateral eye, closely followed by the ipsilateral eye that is transferred from the earlier N170 in the opposite hemisphere. Our results suggest that the deceptively simple N170 ERP hides a complex mechanism of diagnostic visual feature coding involving cross-hemispheric feature transfer. Meeting abstract presented at VSS 2015.

Long-Term Follow-Up of the Repair of the Multiple-Branch Facial Nerve Defect Using Acellular Nerve Allograft

To assess the clinical efficacy of the repair of facial nerve defects by allograft transplantation using acellular facial nerves. Seven patients with facial nerve defects, ranging from damage to 1 facial nerve branch to combined defects of all branches, were enrolled. Defects ranged from 3 to longer than 4cm. All defects were repaired by transplantation of acellular facial nerve allografts. Static and dynamic symmetry and facial expressions were evaluated using the House-Brackmann classification and the functional status of the facial nerve was assessed electromyographically. No patient received immunosuppressive therapy. All wounds healed well, with no swelling or inflammatory exudation. The patients recovered facial nerve function to various extents. Six months postoperatively, 4 of 7 patients showed static facial asymmetry. Twelve months postoperatively, 3 patients had static facial asymmetry with normal eye closure, and only careful observation could detect slight asymmetry of forehead movement. Two of 7 patients showed moderate facial nerve dysfunction. Ipsilateral facial movement and facial asymmetry were obvious in the patient whose defect affected the common trunk and all facial nerve branches. Two years postoperatively, 5 of 7 patients had mild facial nerve dysfunction, with symmetric faces and incomplete eye occlusion. Six years postoperatively, these patients continued to show symmetric faces and incomplete ipsilateral eye occlusion, but facial muscle function was considerably restored. Follow-up electromyography showed neurologic recovery in all patients. The repair of a facial nerve defect by transplantation of an acellular facial nerve allograft is feasible.

Visual Acuity in Birdshot Retinochoroidopathy Evaluation.

To determine the statistical correlation between visual acuity (VA) and various quantitative parameters relevant to birdshot retinochoroidopathy (BRC) evaluation. Hospital-based retrospective observational study. setting: Institutional. Consecutive HLA29+ BRC patients were included between May and August 2013 at a single tertiary center (Pitié-Salpétrière Hospital, Paris). Demographic data and quantitative parameters relevant to BRC at baseline were collected: VA, degree of anterior and posterior inflammatory reaction, foveal thickness measured by optical coherence tomography (OCT), Arden ratio, and electrooculography (EOG) light peak. Correlation between VA and the other parameters of the ipsilateral and fellow eye was performed using Spearman rank correlation coefficients. Fifty-five patients were included. Mean VA was 6/9.5 in the right eye (OD) and 6/12 in the left eye (OS). Mean foveal thickness was 240 μm OD (range: 112-606) and 251 μm OS (range: 85-662). Mean Arden ratio was 159% OD and 160% OS. EOG light peak was 714 mV OD (range: 316-1379) and 746 mV OS (range: 272-1652). VA of a given eye was moderately correlated with VA of the contralateral eye (r = 0.4). On the contrary, all other parameters showed a strong correlation between both eyes (all r > 0.7, P < .01). Overall, none of the studied parameters was correlated with its VA (all r < 0.5). In BRC, visual acuity alone does not seem to fully reflect the disease severity in terms of clinical or ancillary quantitative findings at baseline.

Neurodegeneration and Vision Loss after Mild Blunt Trauma in the C57Bl/6 and DBA/2J Mouse.

Damage to the eye from blast exposure can occur as a result of the overpressure air-wave (primary injury), flying debris (secondary injury), blunt force trauma (tertiary injury), and/or chemical/thermal burns (quaternary injury). In this study, we investigated damage in the contralateral eye after a blast directed at the ipsilateral eye in the C57Bl/6J and DBA/2J mouse. Assessments of ocular health (gross pathology, electroretinogram recordings, optokinetic tracking, optical coherence tomography and histology) were performed at 3, 7, 14 and 28 days post-trauma. Olfactory epithelium and optic nerves were also examined. Anterior pathologies were more common in the DBA/2J than in the C57Bl/6 and could be prevented with non-medicated viscous eye drops. Visual acuity decreased over time in both strains, but was more rapid and severe in the DBA/2J. Retinal cell death was present in approximately 10% of the retina at 7 and 28 days post-blast in both strains. Approximately 60% of the cell death occurred in photoreceptors. Increased oxidative stress and microglial reactivity was detected in both strains, beginning at 3 days post-injury. However, there was no sign of injury to the olfactory epithelium or optic nerve in either strain. Although our model directs an overpressure air-wave at the left eye in a restrained and otherwise protected mouse, retinal damage was detected in the contralateral eye. The lack of damage to the olfactory epithelium and optic nerve, as well as the different timing of cell death as compared to the blast-exposed eye, suggests that the injuries were due to physical contact between the contralateral eye and the housing chamber of the blast device and not propagation of the blast wave through the head. Thus we describe a model of mild blunt eye trauma.

Epicrania Fugax with Sagittal Trajectory of the Pain

Dear Editor, Epicrania fugax (EF) was first described by Pareja et al in 2008 ⇓. It has been recently included in the Appendix of the 3rd edition of The International Classification of Headache Disorders (ICHD-III, beta version) ⇓. It is characterized by ultrabrief paroxysms of unilateral pain spreading from the posterior scalp to the ipsilateral eye or nose, along a linear or zigzag trajectory, and lasting less than 10 s. Pain intensity can be moderate or severe, and pain quality has been described as electric or stabbing. Autonomic symptoms can be present. Pain frequency is extremely variable and most attacks are spontaneous, but some of them can be provoked by tactile stimulation. Between paroxysms, mild pain or hyperesthesia could remain in the stemming area but complete disappearance of pain is also possible ⇓. As the first description of EF, there have been several publications supporting this new entity. A total of 66 cases have been reported up to now, 48 of them sharing the original forward radiation. Conversely, a backward radiation from frontal or periorbital areas toward the occipital region has been described in 18 cases ⇓. Pain paroxysms are strictly unilateral, although some patients have shifting sides ⇓. Associations with other headaches, mainly nummular …

Corneal sensitivity following lacrimal gland excision in the rat.

Dry eye disease (DED) produces ocular pain and irritation, yet a detailed characterization of ocular sensitivity in a preclinical model of DED is lacking. The aim of the present study was to assess nociceptive behaviors in an aqueous tear deficiency model of DED in the rat. Spontaneous blinking, corneal mechanical thresholds, and eye wipe behaviors elicited by hypertonic saline (5.0 M) were examined over a period of 8 weeks following the unilateral excision of either the exorbital lacrimal gland or of the exorbital and infraorbital lacrimal glands, and in sham surgery controls. The effect of topical proparacaine on spontaneous blinking and of systemic morphine (0.5-3.0 mg/kg, subcutaneous [SC]) on spontaneous blinking and eye wipe responses were also examined. Lacrimal gland excision resulted in mechanical hypersensitivity and an increase in spontaneous blinking in the ipsilateral eye over an 8-week period that was more pronounced after infra- and exorbital gland excision. The time spent eye wiping was also enhanced in response to hypertonic saline (5.0 M) at both 1- and 8-week time-points, but only in infra- and exorbital gland excised animals. Morphine attenuated spontaneous blinking, and the response to hypertonic saline in dry eye animals and topical proparacaine application reduced spontaneous blinking down to control levels. These results indicate that aqueous tear deficiency produces hypersensitivity in the rat cornea. In addition, the increase in spontaneous blinks and their reduction by morphine and topical anesthesia indicate the presence of persistent irritation elicited by the activation of corneal nociceptors.

Pathogenesis, Surgical Treatment, and Cure for SUNCT Syndrome

Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) are characterized by attacks of moderate to severe stabbing pain, strictly unilateral, with periorbital or temporal distribution, associated with cranial autonomic symptoms, such as lacrimation and redness of the ipsilateral eye. To obtain mechanistic insights into the pathogenesis of SUNCT syndrome, more than 800 cases treated in our institution during the last 7 years were retrospectively reviewed. Two patients showed typical autonomic symptoms of SUNCT. Magnetic resonance imaging suggested potential compression of the trigeminal nerve by the intracranial artery in these cases and complete remission was achieved by microvascular decompression. Microvascular decompression provides an appropriate therapeutic choice if vascular compression of the trigeminal nerve is identified. From our 2 cases, we propose that, in some cases of SUNCT diagnosed previously, characteristic symptoms were induced by compression of the side surface of the first branch of the trigeminal nerve at the root exit zone by the intracranial artery.

Feasibility of assessment of conjunctival microvascular hemodynamics in unilateral ischemic stroke

Since the internal carotid artery supplies blood to both the eye and the brain, ocular microvascular hemodynamics can be altered due to ischemic stroke. The purpose of the current study was to establish the feasibility of conjunctival microcirculation imaging for detection of inter-ocular differences in microvascular hemodynamics in subjects with unilateral ischemic stroke. Conjunctival microcirculation imaging was performed in both eyes of 15 healthy control subjects and 12 subjects following unilateral ischemic stroke. Diameter and axial blood velocity were measured in multiple conjunctival venules of each eye. A two-way repeated measures analysis of variance was performed to determine the effects of stroke (control vs. stroke) and side of stroke (ipsilateral vs. contralateral) on conjunctival diameter and axial blood velocity. There was no significant main effect of stroke on conjunctival diameter (P=0.7) or conjunctival axial blood velocity (P=0.9). There was no significant main effect of side of stroke on conjunctival diameter (P=0.8), but there was a significant main effect of side of stroke on conjunctival axial blood velocity (P=0.02). There was a significant interaction effect between stroke and side of stroke (P=0.04), indicating that conjunctival axial blood velocity was lower in ipsilateral eyes than in contralateral eyes of stroke subjects. Conjunctival axial blood velocity and internal carotid artery blood velocity were correlated in stroke subjects (r=0.75, P=0.01, N=10). Conjunctival microcirculation imaging is a feasible method to detect inter-ocular differences in microvascular hemodynamics in subjects with unilateral ischemic stroke.

Features of the Retinotopic Representation in the Visual Wulst of a Laterally Eyed Bird, the Zebra Finch (Taeniopygia guttata)

The visual wulst of the zebra finch comprises at least two retinotopic maps of the contralateral eye. As yet, it is not known how much of the visual field is represented in the wulst neuronal maps, how the organization of the maps is related to the retinal architecture, and how information from the ipsilateral eye is involved in the activation of the wulst. Here, we have used autofluorescent flavoprotein imaging and classical anatomical methods to investigate such characteristics of the most posterior map of the multiple retinotopic representations. We found that the visual wulst can be activated by visual stimuli from a large part of the visual field of the contralateral eye. Horizontally, the visual field representation extended from -5° beyond the beak tip up to +125° laterally. Vertically, a small strip from -10° below to about +25° above the horizon activated the visual wulst. Although retinal ganglion cells had a much higher density around the fovea and along a strip extending from the fovea towards the beak tip, these areas were not overrepresented in the wulst map. The wulst area activated from the foveal region of the ipsilateral eye, overlapped substantially with the middle of the three contralaterally activated regions in the visual wulst, and partially with the other two. Visual wulst activity evoked by stimulation of the frontal visual field was stronger with contralateral than with binocular stimulation. This confirms earlier electrophysiological studies indicating an inhibitory influence of the activation of the ipsilateral eye on wulst activity elicited by stimulating the contralateral eye. The lack of a foveal overrepresentation suggests that identification of objects may not be the primary task of the zebra finch visual wulst. Instead, this brain area may be involved in the processing of visual information necessary for spatial orientation.

Sudden onset diplopia in an elderly male patient : answer

Brain diffusion-weighted imaging revealed a small hyperintense lesion involving the median dorsal midbrain (Fig. 1). Aspirin and clopidogrel were prescribed. He was discharged 8 days after onset, at which point his diplopia was slightly improved. Binocular double vision suggests the dysfunction of extraocular muscles, the neuromuscular junction, cranial nerves, cranial nerve nuclei, or internuclear and supranuclear connections [1]. Accurate localization of the underlying lesion is the first step towards the correct diagnosis. Each extraocular muscle is innervated by the corresponding cranial nerve, which originates from the individual cranial nerve nucleus. In complete oculomotor nerve palsy, there is ptosis due to the dysfunction of the levator palpebrae superioris muscle. The eye is deviated down and out, with impaired elevation, depression, and adduction. Pupil involvement usually indicates a compressive lesion, while sparing of the pupil is more likely due to ischemia [1]. The oculomotor nucleus is a paired structure that is located in the midbrain, adjacent to the medial longitudinal fasciculus (MLF) and reticular formation, ventral to the aqueduct of Sylvius and the fourth ventricle. The oculomotor nucleus lesion typically causes ipsilateral ophthalmoparesis and pupil dilatation with bilateral impairment of ocular elevation and bilateral ptosis. Isolated weakness of a single muscle is possible with an oculomotor nucleus lesion and isolated bilateral oculomotor nuclear palsy is extremely rare [2]. Classic signs of internuclear ophthalmoplegia (INO) are the impairment of adduction of the ipsilateral eye and the preservation of abduction of the contralateral eye when the patient tries to gaze in the contralateral direction [3]. It is induced by a lesion involving the MLF in the brainstem. One-and-a-half syndrome consists of lateral gaze palsy in one direction and INO in the other direction with a contralateral gaze. It occurswith lesions in the dorsal pontine tegmentum that impair both the ipsilateral paramedian pontine reticular formation or the abducens nucleus and the ipsilateralMLF.

Cortico-cortical interactions influence binocularity of the primary visual cortex of adult mice.

Electrophysiological studies have revealed that a large proportion of the mouse primary visual cortex (V1) receives input also from the ipsilateral eye. This is surprising as most optic nerve fibers cross at the optic chiasm in mice. Inactivating V1 of one hemisphere has recently demonstrated a strong contribution of one hemisphere's activity on binocularity of single units and visually evoked potentials of V1 in the other hemisphere of young rats and of single units in young adult mice. Here we used intrinsic signal optical imaging to quantitatively study the influence of cortico-cortical connections on the magnitude of neuronal activation in the entire binocular zone of adult mouse V1. We simultaneously measured V1-activity of both hemispheres in adult C57BL/6J mice before and after blocking sensory-driven activity in one hemisphere with muscimol. In V1 contralateral to the inactivation, ipsilateral eye evoked activity was reduced by on average 18% while contralateral eye evoked activity did not change. Our results clearly show that cortico-cortical interactions exert a global amplification of ipsilateral eye evoked activity in adult mouse V1.

Identification of Eye-Specific Domains and Their Relation to Callosal Connections in Primary Visual Cortex of Long Evans Rats.

Ocular dominance columns (ODCs) exist in many primates and carnivores, but it is believed that they do not exist in rodents. Using a combination of transneuronal tracing, in situ hybridization for Zif268 and electrophysiological recordings, we show that inputs from both eyes are largely segregated in the binocular region of V1 in Long Evans rats. We also show that, interposed between this binocular region and the lateral border of V1, there lies a strip of cortex that is strongly dominated by the contralateral eye. Finally, we show that callosal connections colocalize primarily with ipsilateral eye domains in the binocular region and with contralateral eye input in the lateral cortical strip, mirroring the relationship between patchy callosal connections and specific sets of ODCs described previously in the cat. Our results suggest that development of cortical modular architecture is more conserved among rodents, carnivores, and primates than previously thought.

Linear headache: a recurrent unilateral head pain circumscribed in a line-shaped area.

BackgroundA headache circumscribed in a line-shaped area but not confined to the territory of one particular nerve had ever been described in Epicrania Fugax (EF) of which the head pain is moving and ultrashort. In a 25-month period from Feb 2012 to Mar 2014, we encountered 12 patients with a paroxysmal motionless head pain restricted in a linear trajectory. The head pain trajectory was similar to that of EF, but its all other features obviously different from those of EF. We named this distinctive but undescribed type of headache linear headache (LH).MethodsA detailed clinical feature of the headache was obtained in all cases to differentiate with EF, trigeminal autonomic cephalalgias (TACs) and cranial neuralgia. Similarities and differences in clinical features were compared between LH and migraine.ResultsThe twelve LH patients (mean age 43.9 ± 12.2) complained of a recurrent, moderate to severe, distending (n = 9), pressure-like (n = 3) or pulsating (n = 3) pain within a strictly unilateral line-shaped area. The painful line is distributed from occipital or occipitocervical region to the ipsilateral eye (n = 5), forehead (n = 6) or parietal region (n = 1). The pain line has a trajecory similar to that of EF but no characteristics of moving. The headache duration would be ranged from five minutes to three days, but usually from half day to one day in most cases (n = 8). Six patients had the accompaniment of nausea with or without vomiting, and two patients had the accompaniment of ipsilateral dizziness. The attacks could be either spontaneous (n = 10) or triggered by noise, depression and resting after physical activity (n = 1), or by stress and staying up late (n = 1). The frequency of attacks was variable. The patients had well response to flunarizine, sodium valproate and amitriptyline but not to carbamazepine or oxcarbazepine. LH is different from EF, trigeminal autonomic cephalalgias (TACs) and cranial neuralgia, but it had couple of features similar to that of migraine.ConclusionsThe clinical picture of LH might be a subtype of migraine, or represent a novel syndrome.