An unusual case of epilepsy exhibiting gelastic seizure, simple visual hallucination, and transient swelling of the left parieto-occipital region]

We report a 74-year-old man with gelastic seizure, simple visual hallucination, and adversive seizure. The patient described his visual hallucinations as "rotating light like a firefly" and "mimicking a stream". Brain CT scan showed a transient swelling as well as low density of a left parieto-occipital region. Electroencephalographic study revealed spikes and fast waves beginning at left occipital region. Although temporal lobe and hypothalamic lesions (especially hypothalamic hamartomas) are well known as origins of gelastic seizures, we could not find any report that described a series of occurrence of gelastic seizure and simple visual hallucination. Usually, simple visual hallucination is thought to occur in occipital lesion. In our case, it is possible that gelastic seizure and simple visual hallucination are related to the epileptic discharge from occipital lesion directly or indirectly. The reversible brain swelling with low density seen in the present case might be caused by cytotoxic edema due to status epilepticus.     

Do we need a new word to supplement "hallucination"?

The word "hallucination" was used originally (and with etymological correctness) to refer to the unshared sensory experiences of persons who are mentally ill. However, many persons who are not mentally ill also have unshared sensory experiences. A few of these convey information paranormally, but the longstanding association of "hallucination" with mental illness inhibits many persons who have such experiences from reporting them so that they can be studied. The author suggests a new word, "idiophany," to designate all unshared sensory experiences. The word "hallucination" could then be restricted, as it originally was, to the unshared sensory experiences of the mentally ill.     

Thoracic sensory level as a false localizing sign in cervical spinal cord and brain lesions

Background

In rare cases of cervical myelopathy, there may be a discrepancy between the sensory level and the site of cord lesion. This phenomenon is not well recognized. This study sought to investigate the characteristics of patients presenting with a false localizing thoracic sensory level.

Methods

The databases of the neurology clinics of two major tertiary medical centers were reviewed for all patients who presented in 2000–2010 with a main complaint of paraparesis and a thoracic sensory level. Those whose initial thoracic magnetic resonance scan showed no spinal cord pathology were included in the study.

Results

Twelve patients (mean age, 52 ± 31 years) met the study criteria. In all cases, the pathological lesion was visualized on magnetic resonance imaging of the cervical spine or brain. Eight patients had a compressive lesion of the spinal cord and 4 had demyelinating lesions. The difference between the false localizing sensory level and the level of the cervical lesion ranged from 6 to 11 segments.

Conclusion

Patients with a sensory thoracic level and normal findings on thoracic magnetic resonance imaging should be further evaluated with cervical spinal cord and, sometimes, brain imaging to search for potentially treatable lesions.     

Functional and effective connectivity in an fMRI study of an auditory-related task

This study investigates the sets of brain areas that are functionally connected during an auditory goal-directed task. We used a paradigm including a resting state condition and an active condition, which consisted in active listening to the footsteps of walking humans. The regional brain activity was measured using fMRI and the adjusted values of activity in brain regions involved in the task were analysed using both principal component analysis and structural equation modelling. A first set of connected areas includes regions located in Heschl's gyrus, planum temporale, posterior superior temporal sulcus (in the so-called 'social cognition' area), and parietal lobe. This network could be responsible for the perceptual integration of the auditory signal. A second set encompassing frontal regions is related to attentional control. Dorsolateral- and medial-prefrontal cortex have mutual negative influences which are similar to those described during a visual goal-directed task [T. Chaminade & P. Fonlupt (2003) Eur. J. Neurosci., 18, 675-679.]. Moreover, the dorsolateral prefrontal cortex (DLPFC) exerts a positive influence on the auditory areas during the task, as well as a strong negative influence on the visual areas. These results show that: (i) the negative influence between the medial and lateral parts of the frontal cortex during a goal-directed task is not dependent on the input modality (visual or auditory), and (ii) the DLPFC activates the pathway of the relevant sensory modality and inhibits the nonrelevant sensory modality pathway.     

A Review of Multimodal Hallucinations: Categorization,Assessment, Theoretical Perspectives,and Clinical Recommendations

Hallucinations can occur in different sensory modalities, both simultaneously and serially in time. They have typically been studied in clinical populations as phenomena occurring in a single sensory modality. Hallucinatory experiences occurring in multiple sensory systems—multimodal hallucinations (MMHs)—are more prevalent than previously thought and may have greater adverse impact than unimodal ones, but they remain relatively underresearched. Here, we review and discuss: (1) the definition and categorization of both serial and simultaneous MMHs, (2) available assessment tools and how they can be improved, and (3) the explanatory power that current hallucination theories have for MMHs. Overall, we suggest that current models need to be updated or developed to account for MMHs and to inform research into the underlying processes of such hallucinatory phenomena. We make recommendations for future research and for clinical practice, including the need for service user involvement and for better assessment tools that can reliably measure MMHs and distinguish them from other related phenomena.     

Visual projections induced into the auditory pathway of ferrets. I. Novel inputs to primary auditory cortex (AI) from the LP/pulvinar complex and the topography of the MGN-AI projection.

The organization of cortical circuitry responsible for processing sensory information is a subject of intense examination. However, it is not known whether cortical cells in different sensory cortices process information in a way that is specific to the modality of their input, or whether there are commonalities in processing circuitry across different cortices. In our laboratory, this question has been investigated at the level of the geniculocortical pathway by routing information of one sensory modality into the processing circuitry of another modality. Appropriate early lesions cause growth of retinal axons into the auditory thalamus (MGN) (Sur et al., Science 242:1437, '88). Previously, we have established that the MGN carries the resulting visual information on to primary auditory cortex (AI), which thus contains visually responsive neurons and a topographic representation of the retina (Roe et al., Soc. Neurosci. Abstr. 14:460, '88; Sur et al., Science 242:1437, '88). In this paper, we describe anomalous projections from the dorsal part of the thalamus, specifically the lateral posterior/pulvinar complex, into AI. This result demonstrates that thalamic neurons belonging to one modality can be induced to project to cortex that is normally of a different modality. In addition, we have studied in detail the nature of the MGN to AI projection in these animals as compared to the normal projection. The MGN to AI projection appears to be unaltered by the lesions; the location and topography of labelled cells are similar to that in normal animals. Because the MGN to AI projection is still highly divergent along the "isofrequency" dimension when compared to the tonotopic dimension, our data suggest that visual topography in the cortical map is created within the auditory cortex, perhaps by activity-dependent sharpening of the retinal representation during development.     

Brain networks underlying mental imagery of auditory and visual information

Mental imagery is a complex cognitive process that resembles the experience of perceiving an object when this object is not physically present to the senses. It has been shown that, depending on the sensory nature of the object, mental imagery also involves correspondent sensory neural mechanisms. However, it remains unclear which areas of the brain subserve supramodal imagery processes that are independent of the object modality, and which brain areas are involved in modality‐specific imagery processes. Here, we conducted a functional magnetic resonance imaging study to reveal supramodal and modality‐specific networks of mental imagery for auditory and visual information. A common supramodal brain network independent of imagery modality, two separate modality‐specific networks for imagery of auditory and visual information, and a common deactivation network were identified. The supramodal network included brain areas related to attention, memory retrieval, motor preparation and semantic processing, as well as areas considered to be part of the default‐mode network and multisensory integration areas. The modality‐specific networks comprised brain areas involved in processing of respective modality‐specific sensory information. Interestingly, we found that imagery of auditory information led to a relative deactivation within the modality‐specific areas for visual imagery, and vice versa. In addition, mental imagery of both auditory and visual information widely suppressed the activity of primary sensory and motor areas, for example deactivation network. These findings have important implications for understanding the mechanisms that are involved in generation of mental imagery.     

Characterization of whole‐brain task‐modulated functional connectivity in response to nociceptive pain: A multisensory comparison study

Previous functional magnetic resonance imaging (fMRI) studies have shown that brain responses to nociceptive pain, non‐nociceptive somatosensory, visual, and auditory stimuli are extremely similar. Actually, perception of external sensory stimulation requires complex interactions among distributed cortical and subcortical brain regions. However, the interactions among these regions elicited by nociceptive pain remain unclear, which limits our understanding of mechanisms of pain from a brain network perspective. Task fMRI data were collected with a random sequence of intermixed stimuli of four sensory modalities in 80 healthy subjects. Whole‐brain psychophysiological interaction analysis was performed to identify task‐modulated functional connectivity (FC) patterns for each modality. Task‐modulated FC strength and graph‐theoretical‐based network properties were compared among the four modalities. Lastly, we performed across‐sensory‐modality prediction analysis based on the whole‐brain task‐modulated FC patterns to confirm the specific relationship between brain patterns and sensory modalities. For each sensory modality, task‐modulated FC patterns were distributed over widespread brain regions beyond those typically activated or deactivated during the stimulation. As compared with the other three sensory modalities, nociceptive stimulation exhibited significantly different patterns (more widespread and stronger FC within the cingulo‐opercular network, between cingulo‐opercular and sensorimotor networks, between cingulo‐opercular and emotional networks, and between default mode and emotional networks) and global property (smaller modularity). Further, a cross‐sensory‐modality prediction analysis found that task‐modulated FC patterns could predict sensory modality at the subject level successfully. Collectively, these results demonstrated that the whole‐brain task‐modulated FC is preferentially modulated by pain, thus providing new insights into the neural mechanisms of pain processing.     

The hodology of hallucinations

The hodotopic framework is a recent revision of Geschwind's disconnection paradigm incorporating advances in functional and white matter imaging. Its intention is to help clinico-pathological correlations across a range of neurological and psychiatric conditions and generate novel research questions. Here I consider hallucinations within this framework. The paper is divided into three parts. The first reviews the auditory and visual hallucination literature from the dual perspectives of dysfunction localised to specific brain regions (topological) and dysfunction related to connections between brain regions (hodological), combining evidence from tractography, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) studies. Patients prone to hallucinations have complex, task-specific hodological abnormalities that persist between hallucination episodes. During hallucinations, topological increases in activity are found whose location defines hallucination content and modality. Whether these activity increases are accompanied by transient hodological change is unclear. The second part of the paper addresses this issue in EEG and fMRI studies of a 200-year-old paradigm. Photic stimulation within a specific frequency and luminance range induces hallucinations of geometrical patterns, colours and motion in normal subjects. By comparing hallucination-inducing with control stimulation, topological activity increases were identified in visual areas whose specialisations matched the induced hallucination contents. During hallucinations, fMRI connectivity between LGN and cortex changed from a positive to negative relationship while EEG connectivity between occipital and other brain regions increased. The complex and dynamic topological and hodological changes during induced hallucinations are consistent with a shift in thalamocortical circuitry from tonic to burst mode and may have direct relevance to the Charles Bonnet Syndrome. The third part of the paper considers the relevance of the finding to other disorders, examines the strengths and limitations of our current imaging approaches to connectivity and looks to future developments in the field.     

Alpha-coma: clinical and evoked potential studies

Simultaneous brainstem auditory and somatosensory evoked potential studies to median nerve stimulation were performed in two comatose patients, having diffuse alpha-pattern in their EEGs. CT scan of the brain in both cases did not reveal any mass lesion. In Case 1, the clinical and evoked potential studies suggested a brain stem lesion, and in Case 2 there was diffuse encephalopathy, with asymmetric dysfunction of the brainstem as seen in the evoked potential patterns. The suggested separation of alpha-pattern into two distinct groups, based on the reactivity and the presence or absence of sleep activities, into brainstem and diffuse cortical lesions could not be supported by our evoked potential studies. Our study, based on the observations of the evoked potential studies, indicated that the reactivity to sensory stimulation and intermittent attenuation of diffuse alpha-like activity relate to the integrity of the ascending sensory inputs to the thalamus. In the absence of evoked potential data, the localization of lesion(s) in alpha-coma pattern may be imprecise. Moreover, the circadian sleep rhythms and the presence or absence of "sleep spindles" appeared to depend on the inputs of the ascending sensory pathways to the structures generating the sleep activities. The specific neuronal structures generating the alpha-pattern still remain unidentified; however, this pattern seems to be originating from the structures rostral to the mesencephalon, possibly in the thalamic-thalamocortical circuits.     

Auditory and visual connectivity gradients in frontoparietal cortex

A frontoparietal network of brain regions is often implicated in both auditory and visual information processing. Although it is possible that the same set of multimodal regions subserves both modalities, there is increasing evidence that there is a differentiation of sensory function within frontoparietal cortex. Magnetic resonance imaging (MRI) in humans was used to investigate whether different frontoparietal regions showed intrinsic biases in connectivity with visual or auditory modalities. Structural connectivity was assessed with diffusion tractography and functional connectivity was tested using functional MRI. A dorsal–ventral gradient of function was observed, where connectivity with visual cortex dominates dorsal frontal and parietal connections, while connectivity with auditory cortex dominates ventral frontal and parietal regions. A gradient was also observed along the posterior–anterior axis, although in opposite directions in prefrontal and parietal cortices. The results suggest that the location of neural activity within frontoparietal cortex may be influenced by these intrinsic biases toward visual and auditory processing. Thus, the location of activity in frontoparietal cortex may be influenced as much by stimulus modality as the cognitive demands of a task. It was concluded that stimulus modality was spatially encoded throughout frontal and parietal cortices, and was speculated that such an arrangement allows for top–down modulation of modality‐specific information to occur within higher‐order cortex. This could provide a potentially faster and more efficient pathway by which top–down selection between sensory modalities could occur, by constraining modulations to within frontal and parietal regions, rather than long‐range connections to sensory cortices. Hum Brain Mapp 38:255–270, 2017. © 2016 Wiley Periodicals, Inc.     

Crossed cerebellar diaschisis after brainstem infarction

Metabolic depression in the cerebellar hemisphere contralateral to supratentorial stroke termed "Crossed Cerebellar Diaschisis" (CCD) was first described by Baron and coworkers and now interpreted as a transneuronal deactivation resulted from loss of excitatory afferent inputs. Among the cerebrocerebellar pathways possibly involved, the corticopontocerebellar pathway is considered to be the most important to induce CCD. According to the hypothesis that CCD results from the destruction of the corticopontocerebellar pathway, any lesion wherever located in the corticopontocerebellar pathway may induce CCD. Little is known, however, about CCD after the brainstem lesion. Our case presented here showed that a brainstem lesion actually induced CCD and that CCD resulted from transneuronal deactivation. An 80-year-old female was admitted to the neurological department of Kasugai City Hospital because of left-sided hemiparesis of sudden onset on March 19, 1989. On admission and 5 days after admission CT scan of the brain was performed, but no stroke lesion was found. Magnetic resonance imaging of the brain disclosed a localized lesion in the right peduncle and tegmentum of the midbrain. Single photon emission computerized tomography of the brain using N-isopropyl-P-(123I) iodoamphetamine (IMP) performed about a month after admission disclosed decreased blood flow in the left hemisphere of the cerebellum compared with the right one and the findings of CCD were observed.     

The perceptual characteristics of voice-hallucinations in deaf people: insights into the nature of subvocal thought and sensory feedback loops

The study of voice-hallucinations in deaf individuals, who exploit the visuomotor rather than auditory modality for communication, provides rare insight into the relationship between sensory experience and how "voices" are perceived. Relatively little is known about the perceptual characteristics of voice-hallucinations in congenitally deaf people who use lip-reading or sign language as their preferred means of communication. The existing literature on hallucinations in deaf people is reviewed, alongside consideration of how such phenomena may fit into explanatory subvocal articulation hypotheses proposed for auditory verbal hallucinations in hearing people. It is suggested that a failure in subvocal articulation processes may account for voice-hallucinations in both hearing and deaf people but that the distinct way in which hallucinations are experienced may be due to differences in a sensory feedback component, which is influenced by both auditory deprivation and language modality. This article highlights how the study of deaf people may inform wider understanding of auditory verbal hallucinations and subvocal processes generally.     

Functional imaging studies of attention]

Functional organization of the human brain involved in attention has been determined in many human brain imaging studies. Most of these studies focused on brain mechanism related to selective attention using different sensory modality or sub-modality stimuli. Recently, we have shown other aspects of human attentional system, that is spatial attention, using event-related functional MRI. In this study, using delayed sequential saccade paradigm, subjects were forced to pay their attention towards right or left visual field. We could not find significant difference in brain activation patterns between right and left visual field attention tasks. The results are inconsistent to the findings of the previous lesion studies of humans showing spatial neglect. Further collaborative studies of neurological and brain mapping researches should be necessary to understand human higher cognitive functions.     

Enseignements de l’approche organo-dynamique de l’acouphène

Objective

In this article, we make a critical analysis of the Traité des Hallucinations by the French psychiatrist Henri Ey (1900–1977) and his organo-dynamic theory, that is focused on the functional pathology in contrast to the delirious hallucination. The analysis is dedicated in particular to the phenomenology of tinnitus (i.e. ringing in the ear[s]) that is currently labelled a “phantom auditory perception” by contemporary neurosciences.

Method

The analysis was conducted from a thorough reading of the psychiatric work of Henri Ey, mainly his important “Traité des Hallucinations” (2006), “Études psychiatriques” (2006) and “Neurologie et Psychiatrie” (1998). Following his warning regarding a pathological reality (hallucination) that cannot be seized “by draft and outlines”, in this report we address the understanding of the patient's discourse beyond its convergence with the experimental facts.

Results

Because he wanted to include in the pathogeny of his treatise the “most elementary one” – e.g. tinnitus in the auditory sense – Henri Ey felt in the conception he did not support himself, that is to compare hallucination to a “kind of” perception. Having distinguished the delirious from the functional hallucinations (that correlate with sensory deprivation), he could not avoid reifying them within the sensory deficit, leading again to the concept of perception. This remark can be applied to the contemporary neurophysiological model of the “phantom auditory perception”, which also casts the patient's discourse on a frame with its relativity and proportions that belong to the field of perception (“elementary” vs. “complex” phenomena).

Discussion

The paradox of drafting functional hallucination as an elementary perception supports a new perspective on suffering from tinnitus, that is not restricted to an understanding of the convergence between the subjective discourse and a sensory deficit. Beyond a reification of the subjective indication arising inside the body (i.e. tinnitus), the study of the individual enunciation of the suffering appears on the horizon of the organo-dynamic theory. A psychodynamic approach of this new issue on tinnitus has been supported by the author and a colleague.

Conclusions

Whilst today the magnetic resonance imaging seems to nullify the intersubjective reality, by showing visual correlates of this intangible phenomenon, Henri Ey allows us to recognize a surprisingly modern requirement: a psychotherapeutic listening to tinnitus patients has to be iconoclastic. If the aim is to set-up an individual dialogue with the tinnitus sufferer, the clinician must remove in his mind the images he created about it.     

Cerebroretinal vasculopathy mimicking a brain tumor: a case of a rare hereditary syndrome.

We report a 35-year-old man with hereditary cerebroretinal vasculopathy (CRV) characterized by retinal microvascular changes and a right frontal intracerebral mass lesion that suggested a brain tumor. Histopathologic analysis of the patient's brain lesion as well as reviewed specimens of the patient's mother, who had reportedly died of a brain tumor, showed no neoplasia but did show cerebral microvasculopathy. CRV should be considered as a differential diagnosis for patients with intracerebral mass lesions, retinal vascular changes, and a positive family history of "brain tumors."     

Organization of the median and intralaminar nuclei of the thalamus: hypotheses on their role in the onset of certain central pain

Afferent neurons from thalamic median and intralaminar (IL) nuclei arise in the spinal cord, brain stem synapses, substantia nigra, internal pallidum and cerebral cortex, directly and through the intermediary of the reticular nucleus of the thalamus (RT). Efferent neurons terminate in the anterior thalamic nuclei, RT, striatum and cerebral cortex. Tracking methods in the rat have demonstrated that some RT neurons which project towards the IL are surrounded by endings from the posterior ventral nucleus (VP). Electrical stimulation of multiple prosencephalic structures (mainly VP) and of sensory pathways induce responses in IL of brief latency followed by inhibition. Whereas the responses appear to be related to activation of excitatory projections (under the tonic facilitating control of cerebral cortex) the inhibition phases could be related to activation of RT, since they disappear after lesion of the RT. This nucleus could act as a common final pathway of inhibitions exerted on IL in the rat. Studies in this species have demonstrated that a lateral lesion of the thalamus that includes the RT provokes the appearance in IL of abnormal neuronal hyperactivity of a tonic nature and yet still exaggerated by stimuli normally capable of inducing responses of brief duration followed by inhibition. Human studies using a tomoscintigraphic method to determine regional blood flow have shown "hyperactivity" of the thalamic region in patients with pain of central origin during a natural stimulus provoking hyperpathia. This was not observed during painful states without hyperpathia. The working hypothesis proposed is that of a central lesion inducing a hyperpathia provoking pathologic hyperactivity in certain thalamic nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictive, interactive multiple memory systems

Most lesion studies in animals, and neuropsychological and functional neuroimaging studies in humans, have focused on finding dissociations between the functions of different brain regions, for example in relation to different types of memory. While some of these dissociations can be questioned, particularly in the case of neuroimaging data, we start by assuming a "modal model" in which at least three different memory systems are distinguished: an episodic system (which stores associations between items and spatial/temporal contexts, and which is supported primarily by the hippocampus); a semantic system (which extracts combinations of perceptual features that define items, and which is supported primarily by anterior temporal cortex); and modality-specific perceptual systems (which represent the sensory features extracted from a stimulus, and which are supported by higher sensory cortices). In most situations however, behavior is determined by interactions between these systems. These interactions reflect the flow of information in both "forward" and "backward" directions between memory systems, where backward connections transmit predictions about the current item/features based on the current context/item. Importantly, it is the resulting "prediction error"--the difference between these predictions and the forward transmission of sensory evidence--that drives memory encoding and retrieval. We describe how this "predictive interactive multiple memory systems" (PIMMS) framework can be applied to human neuroimaging data acquired during encoding or retrieval phases of the recognition memory paradigm. Our novel emphasis is thus on associations rather than dissociations between activity measured in key brain regions; in particular, we propose that measuring the functional coupling between brain regions will help understand how these memory systems interact to guide behavior.     

Bilateral crossed visuomotor ataxia--a case report

We observed a 55 y.o. right-handed woman, who was suspected of splenium tumor (glioblastoma?) by CT scan and presented bilateral crossed visuomotor ataxia proposed by Rondot et al. Left unilateral apraxia and agraphia were not found, but left unilateral hemialexia was evident by tachistoscopic examinations. In regard to bilateral crossed visuomotor ataxia, we suggested that at least there might be three possible hypotheses about its realization mechanism. (1) Callosal lesion might disconnect heterotopical fibers which runs from one occipital lobe to another frontal lobe. (2) Integrated information of visual and proprioceptive inputs in the parieto-occipital regions could not be transferred mutually to other side of the brain. (3) Functional dissociation between visual perception of "moving" and that of "position" might be the cause of this symptom. Former could be transferred via subcallosal pathway, but latter not transferred due to the callosal lesion. Hypothesis (1) could not explain, at least, "positive aspects" of this symptom, and which hypothesis is most probable might not be decided at present, because anatomical evidence and patho-plastic mechanism are not yet clarified.