Pulvinar Lesions Research Articles

Dorsal pulvinar inactivation leads to spatial selection bias without perceptual deficit

The dorsal pulvinar has been implicated in visuospatial attentional and perceptual confidence processing. Pulvinar lesions in humans and monkeys lead to spatial neglect symptoms, including an overt spatial saccade bias during free choices. However, it remains unclear whether disrupting the dorsal pulvinar during target selection that relies on a perceptual decision leads to a perceptual impairment or a more general spatial orienting and choice deficit. To address this question, we reversibly inactivated the unilateral dorsal pulvinar by injecting GABA-A agonist THIP while two macaque monkeys performed a color discrimination saccade task with varying perceptual difficulty. We used Signal Detection Theory and simulations to dissociate perceptual sensitivity (d-prime) and spatial selection bias (response criterion) effects. We expected a decrease in d-prime if dorsal pulvinar affects perceptual discrimination and a shift in response criterion if dorsal pulvinar is mainly involved in spatial orienting. After the inactivation, we observed response criterion shifts away from contralesional stimuli, especially when two competing stimuli in opposite hemifields were present. Notably, the d-prime and overall accuracy remained largely unaffected. Our results underline the critical contribution of the dorsal pulvinar to spatial orienting and action selection while showing it to be less important for visual perceptual discrimination.

Deep nuclei injury distribution in isolated “basal ganglia–thalamus” (BGT) versus combined “BGT and watershed” patterns of hypoxic–ischaemic injury (HII) in children with cerebral palsy

To compare frequency and distribution of deep nuclei involvement in isolated basal ganglia and ventrolateral thalamus (BGT) versus combined BGT and watershed (BGT-WS) hypoxic-ischaemic injury (HII). A retrospective review was undertaken of the magnetic resonance imaging (MRI) reports of children (0-18 years) with isolated BGT or combined BGT-WS HII. The location and extent of deep nuclear injuries were compared between groups using Fisher's exact test. Of 762 MRI reports, 435 (57%) had isolated BGT and 327 (43%) combined BGT-WS. Isolated BGT showed basal ganglia involvement in 85.1% (n=370) versus 49.8% (n=163) for combined BGT-WS (p<0.01). Sole putamen lesions were more common in isolated BGT (70.3%; 306) versus combined (19.3%; 63; p<0.01). Thalamic involvement was similar between isolated BGT (93.8%; 408) and combined BGT-WS (96.9%; 317; p>0.05). Sole ventrolateral nucleus involvement was more common in isolated BGT (66.6%; 291) while sole pulvinar lesions (25.1%; 82) and whole thalamus lesions (41.6%; 136) were more common in combined BGT-WS (p<0.01). Putamen and ventrolateral nucleus was the most frequent BGT lesion combination in isolated BGT (55.4%) but not in combined BGT-WS (8.6%; p<0.01). Variations in the frequency of deep nuclear lesions between groups may reflect different underlying pathogenetic mechanisms. Therefore, combined BGT-WS patterns may not necessarily indicate a superimposed profound on partial prolonged HII, as other causes such as neonatal hypoglycaemia may cause these.

A Rare Case of Epilepsia Partialis Continua Caused by a Transient Thalamic Pulvinar Lesion

Epilepsia partialis continua (EPC) is a subclass of focal motor status epilepticus. Despite the evidence for a cortical origin, subcortical pathologies-especially those involving the thalamus-have been proposed. Here, we report a case of EPC with focal faciobrachial seizures, with a reversible pulvinar thalamic lesion detected on magnetic resonance imaging (MRI), such as has not previously been reported. An 89-year-old man presented to our emergency department with a three-hour history of right-sided continuous faciobrachial seizure activity. Diffusion-weighted images showed hyperintensity in the left thalamus in the pulvinar region. Follow-up MRI revealed complete resolution of the abnormal signal in the same region. Our case was interesting because of the EPC caused by a transient thalamic pulvinar lesion in an unusual localization in an elderly patient with no previous brain lesions.

Eye position signals in the dorsal pulvinar during fixation and goal-directed saccades.

Sensorimotor cortical areas contain eye position information thought to ensure perceptual stability across saccades and underlie spatial transformations supporting goal-directed actions. One pathway by which eye position signals could be relayed to and across cortical areas is via the dorsal pulvinar. Several studies have demonstrated saccade-related activity in the dorsal pulvinar, and we have recently shown that many neurons exhibit postsaccadic spatial preference. In addition, dorsal pulvinar lesions lead to gaze-holding deficits expressed as nystagmus or ipsilesional gaze bias, prompting us to investigate the effects of eye position. We tested three starting eye positions (-15°, 0°, 15°) in monkeys performing a visually cued memory saccade task. We found two main types of gaze dependence. First, ~50% of neurons showed dependence on static gaze direction during initial and postsaccadic fixation, and might be signaling the position of the eyes in the orbit or coding foveal targets in a head/body/world-centered reference frame. The population-derived eye position signal lagged behind the saccade. Second, many neurons showed a combination of eye-centered and gaze-dependent modulation of visual, memory, and saccadic responses to a peripheral target. A small subset showed effects consistent with eye position-dependent gain modulation. Analysis of reference frames across task epochs from visual cue to postsaccadic fixation indicated a transition from predominantly eye-centered encoding to representation of final gaze or foveated locations in nonretinocentric coordinates. These results show that dorsal pulvinar neurons carry information about eye position, which could contribute to steady gaze during postural changes and to reference frame transformations for visually guided eye and limb movements.NEW & NOTEWORTHY Work on the pulvinar focused on eye-centered visuospatial representations, but position of the eyes in the orbit is also an important factor that needs to be taken into account during spatial orienting and goal-directed reaching. We show that dorsal pulvinar neurons are influenced by eye position. Gaze direction modulated ongoing firing during stable fixation, as well as visual and saccade responses to peripheral targets, suggesting involvement of the dorsal pulvinar in spatial coordinate transformations.

Impaired visual search with paradoxically increased facilitation by emotional features after unilateral pulvinar damage

Posterior thalamic pulvinar nuclei have been implicated in different aspects of spatial attention, but their exact role in humans remain unclear. Most neuropsychological studies of attention deficits after pulvinar lesion have concerned single patients or small samples. Here we examined a group of 13 patients with focal damage to posterior thalamus on a visual search task with faces, allowing us to test several hypotheses concerning pulvinar function in controlling attention to visually salient or emotionally significant stimuli. Our results identified two subgroups of thalamic patients with distinct patterns of attentional responsiveness to emotional and colour features in face targets. One group with lesions located in anterior and ventral portions of thalamus showed intact performance, with a normal facilitation of visual search for faces with emotional (fearful or happy) expressions on both side of space, similar to healthy controls. By contrast, a second group showed a slower and poorer detection of face targets, most severe for neutral faces, but with a paradoxically enhanced facilitation by both colour and emotional features. This second group had lesions centred on the pulvinar, involving mainly the dorso-medial sectors in patients showing enhanced effects of colour features, but extending to more dorso-lateral sectors in those with enhanced effects of emotional features. These findings reveal that pulvinar nuclei are not critical for orienting attention to emotionally or visually salient features, but instead provide new evidence in support of previous hypotheses suggesting an important role in controlling attention in visual scenes with distracting information.

Pulvinar Lesions Disrupt Fear-Related Implicit Visual Processing in Hemianopic Patients.

The processing of emotional stimuli in the absence of awareness has been widely investigated in patients with lesions to the primary visual pathway since the classical studies on affective blindsight. In addition, recent evidence has shown that in hemianopic patients without blindsight only unseen fearful faces can be implicitly processed, inducing enhanced visual encoding (Cecere et al., 2014) and response facilitation (Bertini et al., 2013, 2017) to stimuli presented in their intact field. This fear-specific facilitation has been suggested to be mediated by activity in the spared visual subcortical pathway, comprising the superior colliculus (SC), the pulvinar and the amygdala. This suggests that the pulvinar might represent a critical relay structure, conveying threat-related visual information through the subcortical visual circuit. To test this hypothesis, hemianopic patients, with or without pulvinar lesions, performed a go/no-go task in which they had to discriminate simple visual stimuli, consisting in Gabor patches, displayed in their intact visual field, during the simultaneous presentation of faces with fearful, happy, and neutral expressions in their blind visual field. In line with previous evidence, hemianopic patients without pulvinar lesions showed response facilitation to stimuli displayed in the intact field, only while concurrent fearful faces were shown in their blind field. In contrast, no facilitatory effect was found in hemianopic patients with lesions of the pulvinar. These findings reveal that pulvinar lesions disrupt the implicit visual processing of fearful stimuli in hemianopic patients, therefore suggesting a pivotal role of this structure in relaying fear-related visual information from the SC to the amygdala.

A Novel Missense GLA Mutation (p.G35V) Detected in Hemodialysis Screening Leads to Severe Systemic Manifestations of Fabry Disease in Men and Women

Background/Aims: Fabry disease (FD), an X-linked lysosomal storage disorder, leads to accumulation of globotriaosylceramide. Screening in dialysis patients may identify genetic variants of unknown clinical significance. We aimed to characterize the pathogenicity of a novel GLA gene mutation identified during hemodialysis screening and the histologic findings of early Fabry nephropathy. Methods: One out of 108 male hemodialysis patients screened for FD presented low α-galactosidase A activity. A novel missense mutation (p.G35V) in the GLA gene was detected. Family screening identified 11 additional cases (8 women). Clinical investigation was conducted in 10 patients (index case and 9 relatives). Pathogenicity of the new mutation was investigated by clinical and laboratory tests, cardiac and cranial magnetic resonance imaging, and kidney biopsy. Results: Cardiac manifestations were detected in most patient from both genders, such as left ventricular hypertrophy and short PR interval. White matter lesion was present in 3 women. Pulvinar lesion of the thalamus and ischemic stroke were detected in male patients. Abnormal glomerular filtration rate (GFR) and/or albuminuria were present in 5 patients (3 women). Renal biopsies (n = 7) revealed globotriaosylceramide deposits in different cell types and foot processes effacement in all patients, including women with normal albuminuria. Despite a normal GFR, tubulointerstitial fibrosis ranging from 5 to 20% was present in young women and men with normal or high albuminuria, respectively. Conclusion: The novel missense mutation p.G35V leads to severe systemic manifestations of FD in men and women. Kidney histological changes, including tubulointerstitial fibrosis, may predate albuminuria and GFR changes in adult women. Novel non-invasive markers are required for early detection of Fabry nephropathy.

Relationship between cortex and pulvinar abnormalities on diffusion-weighted imaging in status epilepticus.

The aim of this study was to analyze the pattern of magnetic resonance diffusion-weighted imaging (DWI) findings in status epilepticus in terms of clinical characteristics. Participants comprised 106 patients with status epilepticus who were admitted to our hospital and underwent DWI. Forty-five patients (42.5 %) showed abnormal findings on DWI and were divided into two groups, comprising 26 patients (24.5 %) with cortex lesions alone and 19 patients (17.9 %) with cortex and pulvinar lesions in the same hemisphere. A long duration of status epilepticus (>120 min) tended to be more prevalent among patients with cortex and pulvinar lesions (57.9 %) than among patients with cortex lesions alone (30.8 %) by univariate and multivariate analyses. Todd's palsy tended to be more frequent in patients with abnormalities on DWI (24/45, 53.3 %) than in patients with normal DWI (21/61, 34.4 %). Six of the 26 patients with cortex lesions alone (23.1 %) had taken anti-epileptic drugs before the attack compared to none of the 19 patients with both cortex and pulvinar lesions. The trend toward a longer duration of status epilepticus in patients with both cortex and pulvinar lesions favors a spreading pattern of seizure discharge from cortex to pulvinar via cortico-pulvinar pathways, and anti-epileptic drugs might, to some extent, prevent spreading of seizure discharge from cortex to pulvinar. In addition, existence of high-intensity areas on DWI at the onset of epilepsy may be a predictive factor for the occurrence of Todd's palsy.

Connectivity between the superior colliculus and the amygdala in humans and macaque monkeys: virtual dissection with probabilistic DTI tractography.

It has been suggested that some cortically blind patients can process the emotional valence of visual stimuli via a fast, subcortical pathway from the superior colliculus (SC) that reaches the amygdala via the pulvinar. We provide in vivo evidence for connectivity between the SC and the amygdala via the pulvinar in both humans and rhesus macaques. Probabilistic diffusion tensor imaging tractography revealed a streamlined path that passes dorsolaterally through the pulvinar before arcing rostrally to traverse above the temporal horn of the lateral ventricle and connect to the lateral amygdala. To obviate artifactual connectivity with crossing fibers of the stria terminalis, the stria was also dissected. The putative streamline between the SC and amygdala traverses above the temporal horn dorsal to the stria terminalis and is positioned medial to it in humans and lateral to it in monkeys. The topography of the streamline was examined in relation to lesion anatomy in five patients who had previously participated in behavioral experiments studying the processing of emotionally valenced visual stimuli. The pulvinar lesion interrupted the streamline in two patients who had exhibited contralesional processing deficits and spared the streamline in three patients who had no deficit. Although not definitive, this evidence supports the existence of a subcortical pathway linking the SC with the amygdala in primates. It also provides a necessary bridge between behavioral data obtained in future studies of neurological patients, and any forthcoming evidence from more invasive techniques, such as anatomical tracing studies and electrophysiological investigations only possible in nonhuman species.

Neural correlates of visual motion processing without awareness in patients with striate cortex and pulvinar lesions.

Patients with striate cortex lesions experience visual perception loss in the contralateral visual field. In few patients, however, stimuli within the blind field can lead to unconscious (blindsight) or even conscious perception when the stimuli are moving (Riddoch syndrome). Using functional magnetic resonance imaging (fMRI), we investigated the neural responses elicited by motion stimulation in the sighted and blind visual fields of eight patients with lesions of the striate cortex. Importantly, repeated testing ensured that none of the patients exhibited blindsight or a Riddoch syndrome. Three patients had additional lesions in the ipsilesional pulvinar. For blind visual field stimulation, great care was given that the moving stimulus was precisely presented within the borders of the scotoma. In six of eight patients, the stimulation within the scotoma elicited hemodynamic activity in area human middle temporal (hMT) while no activity was observed within the ipsilateral lesioned area of the striate cortex. One of the two patients in whom no ipsilesional activity was observed had an extensive lesion including massive subcortical damage. The other patient had an additional focal lesion within the lateral inferior pulvinar. Fiber-tracking based on anatomical and functional markers (hMT and Pulvinar) on individual diffusion tensor imaging (DTI) data from each patient revealed the structural integrity of subcortical pathways in all but the patient with the extensive subcortical lesion. These results provide clear evidence for the robustness of direct subcortical pathways from the pulvinar to area hMT in patients with striate cortex lesions and demonstrate that ipsilesional activity in area hMT is completely independent of conscious perception.

Acute visual loss: just the beginning?

A 47-year-old man presented with sudden visual loss, optic disk edema, retinal ischemia, and limited upgaze in the left eye. Initial MRI revealed thickened, enhancing left optic nerve. Extensive work-up for an inflammatory and infiltrative etiology was positive only for Borrelia burgdorferi IgM by Western blot. Six weeks later the patient had numbness and weakness on his left side. MRI showed enhancing lesions extending from the left optic nerve to the optic chiasm, along the visual pathways bilaterally, mainly on the right side from optic tract to lateral geniculate body and pulvinar. Stereotactic biopsy of the right pulvinar lesion revealed glioblastoma. The tumor progressed rapidly, and the patient died 11 weeks after the onset of first symptoms.

Rapid emergence of temporal and pulvinar lesions in MELAS mimicking Creutzfeld-Jakob disease (copy of NEUROLOGY/2011/389635)

Rapid emergence of temporal and pulvinar lesions in MELAS mimicking Creutzfeld-Jakob disease (copy of NEUROLOGY/2011/389635)

Oculomotor integration in patients with a pulvinar lesion

Oculomotor integration in patients with a pulvinar lesion

Rapid emergence of temporal and pulvinar lesions in MELAS mimicking Creutzfeldt-Jakob disease

Hyperintense areas in the pulvinar in fluid-attenuated inversion recovery images and greater hyperintensity in cortical areas in DWI are typical of sporadic Creutzfeldt-Jacob disease (sCJD).1 A 59-year-old woman developed confusion, progressive aphasia, mutism, and fluctuations of vigilance within 2 weeks. MRI revealed abnormalities consistent with sCJD (figure). CSF showed normal cell counts, negative PCR for HSV, elevated lactate (4.6 mmol/L), and increased levels of 14-3-3 and tau protein (1,300 pg/L). There were no periodic sharp-wave complexes on EEG recordings. Magnetic resonance spectroscopy revealed a lactate signal indicative …

Oculomotor integration in patients with a pulvinar lesion

The pulvinar nucleus of the thalamus, with its connections to visual areas and to frontal and parietal oculomotor cortex, might serve as a nexus for integrating cortical control of voluntary eye movements with reflexive eye movements generated by the superior colliculus. To investigate this hypothesis, we tested five patients with a unilateral lesion of the pulvinar on the oculomotor capture paradigm. In this task, participants have to ignore a distractor item and make a saccade to a target in a visual search display. Results showed that the interference of the distractor was stronger when it was presented contralateral to their lesion compared to when it was presented in the ipsilesional visual field. These findings were confirmed by an additional single case experiment in which we measured saccade trajectory deviations as evoked by a single distractor. These results show that the pulvinar is involved in the successful influence of higher order signals (like our goals and intentions) on the guidance of our eye movements.

Thalamus lesions in chronic and acute seizure disorders

Transient signal changes in the pulvinar have been described following status epilepticus. However, we observed persistent thalamus changes after seizures. The purpose of this study was to characterize thalamus changes in patients with seizure disorders and to correlate imaging findings with clinical features. We searched among 5,500 magnetic resonance imaging (MRI) exams performed in patients with seizures and identified 43 patients. The MRI scans of these patients were reviewed and correlated with clinical data. We identified four patterns of thalamus lesions: (a) fluid attenuated inversion recovery-hyperintense pulvinar lesions (20 patients), as known from status epilepticus. Ten patients in this group had a status epilepticus. Among the remaining patients, three had frequent seizures and seven had sporadic seizures. Twelve patients had follow-up exams for a median of 11months. The lesions had persisted in 11/12 cases in the last available exam and were reversible in one case only. In seven cases, cone-shaped thalamus atrophy resulted, (b) linear defects in the medial and anterior thalamus (five patients), accompanied by atrophy of the mamillary body and the fornix in patients with chronic epilepsy, (c) extensive bilateral thalamus lesions in two patients with a syndrome caused by mutation in the mitochondrial polymerase gamma, and (d) other thalamus lesions not associated with the seizure disorder (16 patients). The spectrum of thalamus lesions in patients with seizure disorders is wider than previously reported. Postictal pulvinar lesions can persist and may result in thalamic atrophy. Linear defects in the anterior thalamus are associated with limbic system atrophy.

The dynamic routing model of visuospatial attention

Event Abstract Back to Event The dynamic routing model of visuospatial attention Bruce Bobier1*, Terry Stewart1 and Chris Eliasmith1 1 University of Waterloo, Canada The dynamic control of information routing in the brain has been most extensively studied in the context of visual attention, although the underlying mechanisms employed by the involved neural populations remain unclear. Several models have suggested that selective routing of attended information may be performed by modulating the gain of stimulus representations or by modifying synaptic connection weights. A problem with many such models is that they do not address how these processes are performed at the cellular level, or do so in a biologically implausible manner. Here we present the Dynamic Routing Model (DRM), which frames the problem of visuospatial attention as the dynamic routing information through a hierarchy of topographically organized cortical regions to an object-centered reference frame. In the DRM, the inferior and lateral pulvinar are hypothesized to encode the retinotopic location at which attention should be engaged, and project this signal to cortical control columns in each visual area. Each control column serves to guide information routing for a small group of adjacent visual columns. At each layer, the pulvinar signal is transformed by the cortical control columns to encode the location from which information should be represented. The dendrites of a neuron in a given column encode a vector containing the control signal and its inputs, and the synaptic weights of the dendrites collectively serve to approximate a function that modulates the gain of each input depending on its distance from the location specified by the cortical control signal. We begin by considering the attentional routing performed in a five layer hierarchy, where each layer is reciprocally connected with pulvinar. For each visual column, we can determine the interactions between the control and visual inputs that are required to optimally route information from the focus of attention to an object-centered reference frame at the top layer. After defining this interaction, we next investigate whether this function can be represented within the dendrites. The routing mechanism is the same for all nodes in the hierarchy, and by using the Neural Engineering Framework to model a subset of this large-scale network, we can use this high level mathematical description to analytically derive the optimal connection weights to perform the routing function. Simulation results show that in a model composed of a single cortical control population and nine visual columns, each containing 200 LIF neurons that project to a single output population, the neurons are able to accurately route visual information. We then show that the model accounts for numerous findings from neurophysiological and psychophysical studies, including attentional effects occurring earlier and more strongly in higher cortical areas, dynamic receptive field shifts, center-surround suppression, as well as impairments observed in pulvinar lesion patients. The DRM also generates several predictions concerning the character of the suppressive annulus surrounding the focus of attention, the role of pulvinar in engaging attention, and the computations performed by cortical neurons under attention. Conference: Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010. Presentation Type: Poster Presentation Topic: Poster session III Citation: Bobier B, Stewart T and Eliasmith C (2010). The dynamic routing model of visuospatial attention. Front. Neurosci. Conference Abstract: Computational and Systems Neuroscience 2010. doi: 10.3389/conf.fnins.2010.03.00121 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 Mar 2010; Published Online: 01 Mar 2010. * Correspondence: Bruce Bobier, University of Waterloo, Waterloo, Canada, bbobier@engmail.uwaterloo.ca Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Bruce Bobier Terry Stewart Chris Eliasmith Google Bruce Bobier Terry Stewart Chris Eliasmith Google Scholar Bruce Bobier Terry Stewart Chris Eliasmith PubMed Bruce Bobier Terry Stewart Chris Eliasmith Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

MRI findings in aphasic status epilepticus

Ictal-MRI studies including diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and MR-angiography (MRA) in patients with aphasic status epilepticus (ASE) are lacking. In this report, we aim to describe the consequences of the ASE on DWIs and its impact on cerebral circulation. We retrospectively studied eight patients with ASE confirmed by ictal-EEG, who underwent ictal-MRI shortly after well-documented onset (mean time delay 3 h). ASE consisted in fluctuating aphasia, mostly associated with other subtle contralateral neurological signs such as hemiparesia, hemianopia, or slight clonic jerks. In MRI, six patients showed cortical temporoparietal hyperintensity in DWI and four of them had also ipsilateral pulvinar lesions. Five patients showed close spatial hyperperfusion areas matching the DWI lesions and an enhanced blow flow in the middle cerebral artery. Parenchymal lesions and hemodynamic abnormalities were not associated with seizure duration or severity in any case. The resolution of DWI lesions at follow-up MRI depended on the length of the MRIs interval. In patients with ASE, lesions on DWI in the temporo-parietal cortex and pulvinar nucleus combined with local hyperperfusion can be observed, even when they appear distant from the epileptic focus or the language areas.

Spatial and temporal deficits are regionally dissociable in patients with pulvinar lesions

The pulvinar is an important structure for visual attention function. Spatial and temporal attention was examined in three patients with varying pulvinar lesions. Spatial and temporal deficits were dissociable. The patient with anterior damage showed strong spatial but not temporal attention deficits, while the patient with posterior damage showed clear temporal attention deficits, but much reduced spatial problems. A third patient with intermediate damage showed intermediate behaviours. These findings are discussed within the scope of models of visual attention in which the pulvinar facilitates communication between different brain areas: depending upon the specifics of pulvinar damage, communication with different cortical areas may be degraded, thereby producing distinct patterns of deficit.

Auditory Neglect and the Ear Extinction Effect in Dichotic Listening: A Reply to Beaton and McCarthy (1993)

In our reply to Beaton and McCarthy (1993), we argue that the issue of ear extinction in dichotic listening also should take into account lesion site and lesion extension. When the lesion is primarily affecting the auditory pathways, the resulting dichotic dysfunction may be an ear extinction effect. However, when the lesion is outside of the auditory system, the absence of reports from one ear may be part of a larger cognitive deficit, involving more complex processes, like orientation and attention. Thus, by constraining the definition of an "ear extinction effect" to a perceptual deficit, Beaton and McCarthy confounds the issue of ear extinction with auditory neglect. In our reply we also present some new data from a patient with a left-sided thalamic pulvinar lesion, contrasting his dichotic listening performance with the patient reported in our original 1991 study.