Left V1 Research Articles

TMS Over V5 Disrupts Motion Prediction

Given the vast amount of sensory information the brain has to deal with, predicting some of this information based on the current context is a resource-efficient strategy. The framework of predictive coding states that higher-level brain areas generate a predictive model to be communicated via feedback connections to early sensory areas. Here, we directly tested the necessity of a higher-level visual area, V5, in this predictive processing in the context of an apparent motion paradigm. We flashed targets on the apparent motion trace in-time or out-of-time with the predicted illusory motion token. As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets. However, when we applied functional magnetic resonance imaging-guided, double-pulse transcranial magnetic stimulation (TMS) over left V5 at 13–53 ms before target onset, the detection advantage of in-time targets was eliminated; this was not the case when TMS was applied over the vertex. Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010). Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framework.

Multimodal Assessment of Optokinetic Visual Stimulation Response in Migraine With Aura

This study aimed to assess activation patterns and the hemodynamic response to optokinetic stimulation in migraine with aura patients compared with controls. It has been proposed that altered visual motion processing in striate and extrastriate visual areas is present in migraine patients and might play a role in the pathophysiology of the disease. Besides activating a large visual network, optokinetic stimulation in particular has been shown to provoke symptoms associated with migraine. In this study, we examined the response to visual stimulation in 18 migraine with aura patients compared with 18 healthy controls by using functional magnetic resonance imaging and functional transcranial Doppler, thereby assessing the activation pattern of the visual areas (V1-V5) as well as the vasomotor reactivity of the posterior cerebral artery. For stimulation, we used a vertically rotating optokinetic drum with complex colored figures. Group analysis of migraineurs with aura vs controls revealed different activation patterns in functional magnetic resonance imaging: attenuation of the physiological right lateralization with a significantly increased activation in the left V5 complex, the left area V3, and the right V5 complex. Analysis of the visually evoked flow response of the cerebral blood flow velocity in the posterior cerebral artery showed a larger side-difference of the offset latency (P < .05) and a reduced steepness of the decreasing slope on the left side (P < .05). Combining examinations with a good structural (functional magnetic resonance imaging) and temporal (functional transcranial Doppler) resolution is a novel approach to migraine pathophysiology. Our findings of an altered pattern of activation by optokinetic visual stimulation with hyperresponsiveness in visual areas activated by motion perception (V5 and V3) further strengthen the concept of an interictal motion-processing deficit in migraine. This is complemented by the slower restitution of the visually evoked flow response after stimulus offset in migraine with aura patients.

Teaching Neuro Images : Diagnostic utility of FDG-PET in neurolymphomatosis

A 70-year-old woman with a history of non-Hodgkin lymphoma presented with left-sided facial pain. MRI of the face, orbit, and neck was negative (figure). A week later, she developed hypesthesia in a V3 distribution. Repeat MRI was again nondiagnostic but fluorodeoxyglucose (FDG)-PET showed increased uptake along the left V3 branch of the trigeminal nerve, as well as in the parotid gland. Biopsy of the left parotid confirmed recurrent lymphoma.

Ultrasound-Guided Infraorbital Nerve Pulsed Radiofrequency Treatment for Intractable Postherpetic Neuralgia - A Case Report -

A 60-year-old man presented with pain on the left cheek and lateral nose. The patient had been diagnosed with facial herpes zoster in the left V2 area 6 months previously. Medical treatment was prescribed for 6 months but it had little effect. We blocked the left infraorbital nerve under ultrasound guidance, but pain relief was short term. Therefore, we performed pulsed radiofrequency treatment on the left infraorbital nerve under ultrasound guidance. Six months after the procedure, the reduction of pain was still maintained, and there was no need for further management.

Facial pain

A 63-year-old woman is referred for neurologic consultation because of electrical shocks of pain in a left V3 distribution. The attacks are very brief, but occur many times a day, triggered by cold, touch, and chewing. In between attacks, she is pain free. Her neurologic examination is normal. This straightforward presentation of trigeminal neuralgia leaves the consulting neurologist wondering what to do with the other 45 minutes of the visit. The current article is vignette-based and deals with patients who may not fit into such a neat category. It is meant for the general neurologist, not the headache specialist. Aside from routine scenarios, it includes discussions of atypical facial pain, temporomandibular joint disorder, burning mouth syndrome, and other vexing types of facial pain.

Vertebral artery dissection associated with viral meningitis

BackgroundVertebral artery dissection (VAD) is often associated with trauma or occurs spontaneously, inevitably causing some neurological deficits. Even though acute infection can be related to the development of spontaneous VAD (sVAD), VAD associated with viral meningitis has never been reported in the literature.Case presentationA 42-year-old man with fever, sore throat, and runny nose developed sudden onset of occipital headache, vertigo, transient confusion, diplopia, and ataxia. Brain stem encephalitis was diagnosed initially because the cerebrospinal fluid (CSF) study showed inflammatory changes. However, subsequent diffusion-weighted (DWI) magnetic resonance imaging of his brain demonstrated left lateral medullary infarction, and the digital subtraction angiography (DSA) confirmed VAD involving left V4 segment of the artery. Consequently, the patient was diagnosed as VAD accompanied by viral meningitis.ConclusionThis case suggests that viral meningitis might lead to inflammatory injury of the vertebral arterial wall, even sVAD with multiple neurological symptoms.

Pitfall of vertebral artery insonation: Bidirectional flow without subclavian artery pathology

A bidirectional flow pattern within the intracranial segment of the vertebral artery (V4–VA) should be indicative of a proximal steno-occlusive disorder of the ipsilateral subclavian artery (SA). Here we present two patients revealing this ultrasound finding without evidence of a specific SA pathology. In case 1 duplex sonography revealed a diameter of the left V2–VA of 3.3 mm and 2.7 mm on the right side. Normal flow signals were detected in the left V2–VA, a systolic flow deceleration was seen on the right side. Intracranially, a biphasic flow pattern was observed in the right V4–VA. The left V4–VA, the basilar artery and the brachial arteries (BrA) as well as the cuff-test were normal. Conventional angiography ruled out a SA or VA pathology. A bilateral fetal-type posterior cerebral artery (FT-PCA) was seen. CT angiography demonstrated a small diameter of the right intracranial V4–VA close to the basilar confluens. In case 2 VA diameter of the left and right V2–VA was 3.3 and 2.3 mm, respectively. Flow signals, similar to case 1 were observed in the non-dominant V2–VA and V4–VA segment. The remaining vessels and the cuff-test were normal. MR angiography demonstrated a FT-PCA and an incomplete posterior inferior cerebellar artery (PICA)-ending VA on the right side. A bidirectional flow in V4–VA can not prove a subclavian steal phenomenon. A normal triphasic flow signal of the brachial artery excludes a relevant proximal obstruction of the SA. Also, diameter measurements of the VA are mandatory. It seems that physiological variants of the vertebrobasilar circulation like a VA hypoplasia, PICA-ending VA or FT-PCA might also cause the above type of VA flow pattern.

Adaptation to Cortical Noise Induced by Transcranial Magnetic Stimulation to the Occipital Lobe

Transcranial magnetic stimulation (TMS) is increasingly used as a method to modify and study functional brain activity. However, results from various studies have produced conflicting theories on how TMS of cortical tissue influences ongoing visual processing. To investigate this issue, single pulse TMS was applied over left V1 in five healthy subjects during an orientation discrimination task (vertical vs. horizontal) using a Gabor patch (2 c/deg, presented 6° in the right visual field). Stimulus contrast was set to each individual's threshold, measured in the absence of TMS. When TMS was applied over V1 performance decreased in all observers (by 1.2–8.7%) compared to accuracy levels obtained during stimulation of a control site (Cz). Crucially, accuracy levels during V1 stimulation gradually improved across blocks of 200 trials in some subjects, whereas performance remained stable during control site stimulation. In contrast, this pattern of recovery was not found in an analogous backward masking paradi...

Pearls &amp; Oy-sters: A distinctive watershed area in the vertebrobasilar territory

The middle cerebellar peduncles may represent a distinctive watershed area in the vertebrobasilar circulation between the anterior inferior and superior cerebellar arteries. A 78-year-old man experienced 2 short-lasting episodes of vertigo with unstable gait during the 5 days before admission. One week previously, he had carried large fiberboard panels, involving sustained rotation of the neck in both directions. His past medical history included arterial hypertension and dyslipidemia. The initial general and neurologic examination was normal except for high blood pressure (194/109 mm Hg). Over the next few days, the patient developed rapidly worsening bilateral dysmetria and dysdiadochokinesia, more marked on the left, cerebellar dysarthria, and unstable stance and gait. Cerebral CT showed leukoaraiosis and lacunar sequelae of both corona radiata and of the left thalamus and caudate nucleus. CT arteriography showed narrowing and irregularities of the V2 segment of the left vertebral artery and occlusion of its V3 segment. Ultrasonography and Doppler examination confirmed the stenosis of the left V2 segment and occlusion of the left V4 segment. There was also an 80% stenosis in the V2 segment of the right vertebral artery. Cerebral MRI showed symmetric acute ischemia of both middle cerebellar peduncles (MCPs) and of the deep right cerebellar hemisphere (figure, A). Fat saturation sequences showed a wall hematoma …

Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex

Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex "control" site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks.

Activation in left primary visual cortex representing parafoveal visual field during reading Japanese texts

Activation in the left primary visual cortex (V1) representing the parafoveal field during text reading has been interpreted as attentional modulation in the process of deciding saccadic target for reading ahead. Kanji words serve the main cue to decide the goal of saccades in Japanese. We aimed to determine the exact location of this modulation in the V1 and to determine whether the area of the modulation changes according to the location where the next Kanji word appears or it is fixed on a certain region in V1. Using functional magnetic resonance imaging, we determined the area in V1 representing each eccentricity on the horizontal meridian of the visual field for each participant. Then we investigated brain activation while they were reading two sets of Japanese texts that scrolled leftward as the participants. In set 1, the distance between the heads of adjacent Kanji words was about 3°. In set 2, the distance was about 5°. From the results of these experiments, we obtained activation amplitude of the area corresponding to each eccentricity. We recorded eye movements simultaneously with the acquisition of fMRI data. The maximum peak of the activation was found in the region representing about 4.5° of eccentricity on the horizontal meridian in the left V1 for each participant. The activation pattern did not essentially differ between the two text conditions, although the location of the saccades made for reading next section of the text corresponds to the head of the next Kanji word. The activation modulation during reading Japanese texts occurs in the parafoveal V1 of the left hemisphere. The attentional modulation did not change with the distance to the next goal of saccade but was fixed on the area representing about 4.5° of eccentricity.

Medulla oblongata injury caused by an acupuncture needle; warning for serious complications due to a common method of alternative medicine

Acupuncture has become popular and an increasing number of procedures are performed worldwide. While acupuncture is generally considered safe, complications can occur due to its nature of insertion of sharp needles into the skin. Neurological complications are rare but reports have included peripheral nerve injury and spinal cord injuries [1–6]. Because of protection by the cranium, complications involving the brain are rare, and only a few cases have been reported [1, 7–9]. We report here a rare case of injury to the medulla oblongata due to migration of an acupuncture needle. A 44-year-old man presented with abnormal sensation 6 days after acupuncture treatment for stiff neck. He had felt dull pain on his left cheek and left back teeth after the course of the treatment. However, there was no dental problem on examination by a dentist. On admission, he had dysesthesia and pain in his left leg, and pain in the left V1 and V2 area of the face when he turned his neck. Computed tomography showed an acupuncture needle sticking the medulla oblongata (Fig. 1a), and the tip of the needle was located near the left vertebral artery (Fig. 1b). As there was risk of further injury to medulla oblongata and vertebral artery, emergent surgery was performed under general anesthesia. Extreme care was taken not to move the needle around the procedure to expose the needle. After removal of the needle the surface of the medulla oblongata was observed through a small craniotomy to rule out active bleeding (Fig. 1d). After the operation, facial pain persisted and an abnormal sensation of heat and pain appeared in the right leg. T2-weighted MRI showed a high intensity lesion in the area that had been pricked by the needle (Fig. 1e). His symptoms were gradually relieved, and he was discharged with dysesthesia in the left face and left leg. Although acupuncture is generally considered safe, complications can occur and sometimes result in a serious outcome [10, 11]. Among complications of the central nervous system, there have been reports of spinal cord injuries [2–6]. Brain injury is extremely rare, but can happen in the cases in which the needle is placed near the cervico-cranial junction, by migration of the needle through the foramen magnum [1, 7–9]. In our case, neurological symptoms appeared several days after the acupuncture session, and showed a progressive course. The broken needle had been overlooked and was left in the suboccipital muscle layer. As the tip of the needle remained sharp and the other end was dull, it might have gradually advanced inward piercing the dura mater and becoming lodged to the medulla oblongata. There are several case reports describing the delayed appearance of the symptoms [2, 9] due to similar mechanisms. The needle should be removed emergently to prevent further injury of nervous system and vasculature. First, the neck must be immobilized using a hard collar to prevent the needle from progressing further. At the introduction of general anesthesia, the patient was intubated with the help of an endoscope to prevent moving the needle by retroflexion of the cervix. Radiological diagnosis requires special attention. Although regular disposable acupuncture needles are made S. Fukaya T. Kimura (&) A. Morita Department of Neurosurgery and Stroke Unit, NTT Medical Center Tokyo, 5-9-22 Higashigotannda, Shinagawa-ku, Tokyo 141-8625, Japan e-mail: tkim-tky@umin.ac.jp

Callosal connections of primary visual cortex predict the spatial spreading of binocular rivalry across the visual hemifields

In binocular rivalry, presentation of different images to the separate eyes leads to conscious perception alternating between the two possible interpretations every few seconds. During perceptual transitions, a stimulus emerging into dominance can spread in a wave-like manner across the visual field. These traveling waves of rivalry dominance have been successfully related to the cortical magnification properties and functional activity of early visual areas, including the primary visual cortex (V1). Curiously however, these traveling waves undergo a delay when passing from one hemifield to another. In the current study, we used diffusion tensor imaging (DTI) to investigate whether the strength of interhemispheric connections between the left and right visual cortex might be related to the delay of traveling waves across hemifields. We measured the delay in traveling wave times (ΔTWT) in 19 participants and repeated this test 6 weeks later to evaluate the reliability of our behavioral measures. We found large interindividual variability but also good test–retest reliability for individual measures of ΔTWT. Using DTI in connection with fiber tractography, we identified parts of the corpus callosum connecting functionally defined visual areas V1–V3. We found that individual differences in ΔTWT was reliably predicted by the diffusion properties of transcallosal fibers connecting left and right V1, but observed no such effect for neighboring transcallosal visual fibers connecting V2 and V3. Our results demonstrate that the anatomical characteristics of topographically specific transcallosal connections predict the individual delay of interhemispheric traveling waves, providing further evidence that V1 is an important site for neural processes underlying binocular rivalry.

Neural substrates in color processing: A comparison between painting majors and non-majors

Although several studies provide evidence of differences in the neural mechanisms of art professionals and non-professionals, little is known about the neural mechanism differences between painting professionals/majors and non-professionals/non-majors during color processing. For the first time, we compared functional activation patterns, functional connectivity during both color naming and passive color viewing, and gray-matter density in 12 painting majors and 12 controls through both functional and structural magnetic resonance imaging techniques. Inter-group comparisons revealed that the painting majors showed more activation in the color selective areas and increased correlation between left V4 and the left ventral lateral prefrontal cortex during color naming. In contrast, the controls exhibited stronger activity in the Broca's area during color naming. Moreover, increased gray matter density in the left V4 complex was found when the painting majors were compared to the controls. This study demonstrates that the left V4 complex shows both functional and structural differences between painting majors and non-majors. In addition, the results suggest the reorganization of the brain circuit underlying lexical retrieval during color naming in the anterior regions of the painting major group.

P-020 The transcirculation treatment of cerebral aneurysms

IntroductionUnfavorable anatomy can preclude embolization of intracranial aneurysms. Transcirculation techniques, in which a catheter is navigated from one side of the brain to the other or from the anterior to...

Endovascular Treatment of a Fusiform Cerebral Aneurysm by Stenting Alone

This paper illustrates two cases of stent-in-stenting treatment of unruptured, symptomatic, fusiform intracerebral aneurysms. Two unruptured symptomatic fusiform intracerebral aneurysms were treated by the stent-in-stent only technique. The first patient, a 35-year-old woman, had a partially thrombosed fusiform aneurysm in the left carotid siphon with the chief complaint of headache and left ophthalmoplegia. The second patient, a 60-year-old man, had a symptomatic fusiform aneurysm of the left V4 with recurrent transient ischemic attacks. No cervical trauma or infection was present in either patient. A CT, CTA and DSA were performed on hospital admission. Both patients were previously premedicated with Clopidrogel + ASA for five days before treatment. By DSA, both patients were treated under general anesthesia with a heparin protocol plus ASA (500mg) at stent placement. A double stent-in stent was placed in both patients. Post-intervention medical therapy was clopridogel and ASA for three months, then aspirin (100mg) daily for six months. CTA and DSA were performed at six and 12 months. Both stents were positioned without any difficulty and could be navigated within cerebral arteries without any exchange procedure, and thanks to their retractability, they were accurately positioned. No bleeding at post-treatment CT was noted. At 12 months follow-up, a complete disappearance of the aneurysm and preservation of the parent vessel was observed for both patients. No procedure-related complication occurred. No intra-stent stenosis or intimal hyperplasia was observed. Stenting for fusiform aneurysms is a safe procedure without complications. Medical therapy pre-post procedure associated with follow-up is necessary to prevent/establish the incidence of occlusion.

Time-resolved, contrast-enhanced 3D MR angiography in the subclavian steal effect

The subclavian steal effect indicates atherosclerotic disease of the supraaortic vessels but rarely causes cerebrovascular events in itself. Noninvasive imaging providing detailed anatomic as well as hemodynamic information would therefore be desirable. From a group of 25 consecutive patients referred for MR angiography, four with absent or highly attenuated signal in one of the vertebral arteries on 3D multislab time-of-flight MR angiography were selected to undergo 3D time-resolved contrast-enhanced MR angiography. The time-resolved 3D contrast series (source images and MIPs) were evaluated visually and by graphic analysis of time-intensity curves derived from the respective V1 and V3 segments of both vertebral arteries on the source images. In two cases with high-grade proximal left subclavian stenosis, time-resolved 3D ce-MRA was able to visualise retrograde contrast filling of the left VA. There was a marked delay in time-to-peak between the left and right V1 segments in one case and a shallower slope of enhancement in another. In the other two cases, there was complete or collateralised segmental occlusion of the VAs.

Radial Biases in the Processing of Motion and Motion-Defined Contours by Human Visual Cortex

Luminance gratings reportedly produce a stronger functional magnetic resonance imaging (fMRI) blood oxygen level-dependent (BOLD) signal in those parts of the retinotopic cortical maps where they are oriented radially to the point of fixation. We sought to extend this finding by examining anisotropies in the response of cortical areas V1-V3 to motion-defined contour stimuli. fMRI at 3 Tesla was used to measure the BOLD signal in the visual cortex of six human subjects. Stimuli were composed of strips of spatial white noise texture presented in an annular window. The texture in alternate strips moved in opposite directions (left-right or up-down). The strips themselves were static and tilted 45 degrees left or right from vertical. Comparison with maps of the visual field obtained from phase-encoded retinotopic analysis revealed systematic patterns of radial bias. For motion, a stronger response to horizontal was evident within V1 and along the borders between V2 and V3. For orientation, the response to leftward tilted contours was greater in left dorsal and right ventral V1-V3. Radial bias for the orientation of motion-defined contours analogous to that reported previously for luminance gratings could reflect cue-invariant processing or the operation of distinct mechanisms subject to similar anisotropies in orientation tuning. Radial bias for motion might be related to the phenomenon of "motion streaks," whereby temporal integration by the visual system introduces oriented blur along the axis of motion. We speculate that the observed forms of radial bias reflect a common underlying anisotropy in the representation of spatiotemporal image structure across the visual field.

Childhood Sexual Abuse Is Associated with Reduced Gray Matter Volume in Visual Cortex of Young Women

Childhood sexual abuse (CSA) has been associated with alterations in brain morphology using region of interest analyses that have focused on stress-sensitive target regions. This study was designed to ascertain the effects on gray matter volume (GMV) of exposure to CSA in healthy young adult college students selected based on exposure history regardless of psychiatric outcome. Voxel-based morphometry (VBM) provided unbiased delineation of the most significantly affected brain regions. High-resolution T1-weighted magnetic resonance imaging (MRI) datasets were obtained for 23 unmedicated female subjects with CSA and 14 healthy female control subjects of equivalent age and socioeconomic status with no history of trauma. Cortical surface-based analysis (FreeSurfer) was performed to verify VBM results. Gray matter volume was reduced by 12.6% and 18.1% in right and left primary visual (V1) and visual association cortices of abused subjects. This reduction was directly related to duration of CSA before age 12. Gray matter volume of left and right V1 correlated with measure of visual memory (r = .353, p = .032 and r = .448, p = .005). Cortical surface-based analysis indicated that GMV of abused subjects was reduced in the left fusiform (p = .004), left middle occipital (p = .04), and right lingual (p = .002) gyri. Early visual experience exerts a strong influence on the developing mammalian visual cortex. Present findings indicate that exposure to CSA may also affect the development of this region and are apparent even in a population of subjects who are sufficiently healthy to matriculate.

Changes in connectivity after visual cortical brain damage underlie altered visual function

The full extent of the brain's ability to compensate for damage or changed experience is yet to be established. One question particularly important for evaluating and understanding rehabilitation following brain damage is whether recovery involves new and aberrant neural connections or whether any change in function is due to the functional recruitment of existing pathways, or both. Blindsight, a condition in which subjects with complete destruction of part of striate cortex (V1) retain extensive visual capacities within the clinically blind field, is an excellent example of altered visual function. Since the main pathway to the visual cortex is destroyed, the spared or recovered visual ability must arise from either an existing alternative pathway, or the formation of a new pathway. Using diffusion-weighted MRI, we show that both controls and blindsight subject GY, whose left V1 is destroyed, show an ipsilateral pathway between LGN (lateral geniculate nucleus) and human motion area MT+/V5 (bypassing V1). However, in addition, GY shows two major features absent in controls: (i) a contralateral pathway from right LGN to left MT+/V5, (ii) a substantial cortico-cortical connection between MT+/V5 bilaterally. Both observations are consistent with previous functional MRI data from GY showing enhanced ipsilateral activation in MT+/V5. There is also evidence for a pathway in GY from left LGN to right MT+/V5, although the lesion makes its quantification difficult. This suggests that employing alternative brain regions for processing of information following cortical damage in childhood may strengthen or establish specific connections.