Unilateral Lesions Of Auditory Cortex Research Articles

Auditory-cortex lesions impair contralateral tone-pattern detection under informational masking

Impaired hearing contralateral to unilateral auditory-cortex lesions is typically only observed under conditions of perceptual competition, such as dichotic presentation or speech in noise. It remains unclear, however, if the source of this effect is direct competition in frequency-specific neurons, or if enhanced processing load in more distant frequencies can also impair auditory detection. To evaluate this question, we studied a group of patients with unilateral auditory-cortex lesions (N = 14, six left-hemispheric (LH), eight right-hemispheric (RH); four females; age range 26–72 years) and a control group (N = 25; 15 females; age range 18–76 years) with a target-detection task in presence of a multi-tone masker, which can produce informational masking. The results revealed reduced sensitivity for monaural target streams presented contralateral to auditory-cortex lesions, with an approximately 10% higher error rate in the contra-lesional ear. A general, bilateral reduction of target detection was only observed in a subgroup of patients, who were classified as additionally suffering from auditory neglect. These results demonstrate that auditory-cortex lesions impair monaural, contra-lesional target detection under informational masking. The finding supports the hypothesis that neural mechanisms beyond direct competition in frequency-specific neurons can be a source of impaired hearing under perceptual competition in patients with unilateral auditory-cortex lesions.

Chapter 31 - Auditory neglect and related disorders

Neglect is a neurologic disorder, typically associated with lesions of the right hemisphere, in which patients are biased towards their ipsilesional - usually right - side of space while awareness for their contralesional - usually left - side is reduced or absent. Neglect is a multimodal disorder that often includes deficits in the auditory domain. Classically, auditory extinction, in which left-sided sounds that are correctly perceived in isolation are not detected in the presence of synchronous right-sided stimulation, has been considered the primary sign of auditory neglect. However, auditory extinction can also be observed after unilateral auditory cortex lesions and is thus not specific for neglect. Recent research has shown that patients with neglect are also impaired in maintaining sustained attention, on both sides, a fact that is reflected by an impairment of auditory target detection in continuous stimulation conditions. Perhaps the most impressive auditory symptom in full-blown neglect is alloacusis, in which patients mislocalize left-sided sound sources to their right, although even patients with less severe neglect still often show disturbance of auditory spatial perception, most commonly a lateralization bias towards the right. We discuss how these various disorders may be explained by a single model of neglect and review emerging interventions for patient rehabilitation.

Comparison of auditory deficits associated with neglect and auditory cortex lesions

In contrast to lesions of the visual and somatosensory cortex, lesions of the auditory cortex are not associated with self-evident contralesional deficits. Only when two or more stimuli are presented simultaneously to the left and right, contralesional extinction has been observed after unilateral lesions of the auditory cortex. Because auditory extinction is also considered a sign of neglect, clinical separation of auditory neglect from deficits caused by lesions of the auditory cortex is challenging. Here, we directly compared a number of tests previously used for either auditory-cortex lesions or neglect in 29 controls and 27 patients suffering from unilateral auditory-cortex lesions, neglect, or both. The results showed that a dichotic-speech test revealed similar amounts of extinction for both auditory cortex lesions and neglect. Similar results were obtained for words lateralized by inter-aural time differences. Consistent extinction after auditory cortex lesions was also observed in a dichotic detection task. Neglect patients showed more general problems with target detection but no consistent extinction in the dichotic detection task. In contrast, auditory lateralization perception was biased toward the right in neglect but showed considerably less disruption by auditory cortex lesions. Lateralization of auditory-evoked magnetic fields in auditory cortex was highly correlated with extinction in the dichotic target-detection task. Moreover, activity in the right primary auditory cortex was somewhat reduced in neglect patients. The results confirm that auditory extinction is observed with lesions of the auditory cortex and auditory neglect. A distinction can nevertheless be made with dichotic target-detection tasks, auditory-lateralization perception, and magnetoencephalography.

The role of the auditory cortex in fear conditioning to complex auditory stimuli

Event Abstract Back to Event The role of the auditory cortex in fear conditioning to complex auditory stimuli Simon Rumpel1* 1 Research Institute of Molecular Pathology, Austria Auditory cued fear conditioning (AFC) is a widely used associative learning paradigm in which animals learn to associate a neutral stimulus (CS, conditioned stimulus), usually a pure tone, with an aversive stimulus (US, unconditioned stimulus), e.g. a foot shock. Subsequently, animals show fear-related behaviour when the CS is presented alone. In the amygdala, a putative site of tone-shock association, auditory and sensory input converge onto individual cells and projections from the amygdala to output brain areas, e.g. the brainstem, mediate fear behaviour. Auditory information reaches the amygdala via different pathways, a direct thalamic pathway and a more indirect thalamo-cortical pathway. Interestingly, AFC induces plastic changes in the auditory cortex, as neurons shift their frequency towards that of a pure tone CS. Hence, it is striking that the auditory cortex seems dispensable: AFC is not impaired in animals with a lesioned thalamo-cortical pathway. We probed the role of the auditory cortex in AFC in which the CS was a complex sound. We hypothesized that complex sounds may resemble sounds occurring in natural learning situations more closely than commonly used pure tones. AFC with a complex CS was feasible in wild type mice within one training session and created a robust, long lasting memory: In memory tests one or four days after training mice showed significant freezing levels during CS presentation compared to baseline. Bilateral auditory cortex lesions after training decreased acquired freezing levels to baseline levels, suggesting that the auditory cortex is involved in AFC with complex sounds in the intact brain. Importantly, also pre-training bilateral auditory cortex lesions abolished freezing to the complex CS. Despite these strong effects, lesioned animals could still be retrained to a pure tone CS. This finding demonstrates that the learning deficit following lesions was highly dependent on the features of the CS. AFC with a complex CS was not significantly impaired in mice with unilateral auditory cortex lesions. In a further series of experiments we aimed to elucidate principle features of complex CS that render the auditory cortex necessary for AFC. We used a frequency-modulated pure tone, an amplitude-modulated pure tone or a pseudo chord, which consisted of multiple constant frequencies. We observed that AFC with a pseudo chord showed strongest sensitivity to lesions, indicating that the auditory cortex may play a role in binding of simultaneous auditory information. Our findings emphasize how small changes in the experimental setup can lead to drastic changes in the brain circuits involved. Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Oral Presentation Topic: Symposia lectures Citation: Rumpel S (2009). The role of the auditory cortex in fear conditioning to complex auditory stimuli. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.049 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: 05 Jun 2009; Published Online: 05 Jun 2009. * Correspondence: Simon Rumpel, Research Institute of Molecular Pathology, Vienna, Austria, rumpel@imp.ac.at 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 Simon Rumpel Google Simon Rumpel Google Scholar Simon Rumpel PubMed Simon Rumpel 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.

Global versus local processing of frequency-modulated tones in gerbils: An animal model of lateralized auditory cortex functions

Hemispheric asymmetries of speech and music processing might arise from more basic specializations of left and right auditory cortex (AC). It is not clear, however, whether such asymmetries are unique to humans, i.e., consequences of speech and music, or whether comparable lateralized AC functions exist in nonhuman animals, as evolutionary precursors. Here, we investigated the cortical lateralization of perception of linearly frequency-modulated (FM) tones in gerbils, a rodent species with human-like low-frequency hearing. Using a footshock-reinforced shuttle-box avoidance go/no-go procedure in a total of 178 gerbils, we found that (i) the discrimination of direction of continuous FM (rising versus falling sweeps, 250-ms duration) was impaired by right but not left AC lesions; (ii) the discrimination of direction of segmented FM (50-ms segments, 50-ms silent gaps, total duration 250 ms) was impaired by bilateral but not unilateral AC lesions; (iii) the discrimination of gap durations (10-30 ms) in segmented FM was impaired by left but not right AC lesions. AC lesions before and after training resulted in similar effects. Together, these experiments suggest that right and left AC, even in rodents, use different strategies in analyzing FM stimuli. Thus, the right AC, by using global cues, determines the direction of continuous and segmented FM but cannot discriminate gap durations. The left AC, by using local cues, discriminates gap durations and determines FM direction only when additional segmental information is available.

Blindsight

Blindsight

Role of the forebrain in sound localization

The ablation-behavior method has been used to study the role of the auditory forebrain in the localization of sound. Bilateral ablation of auditory cortex in carnivores and primates results in a severe impairment in the ability to locate the source of a sound. Though the animals do, under certain conditions, show a residual ability to discriminate sounds on the basis of locus, the cortical sound localization deficit is nonetheless quite severe and can be demonstrated even in tasks which do not require the animal to approach the source of the sound (i.e., conditioned suppression). Furthermore, unilateral auditory cortex lesions cause an impairment in the localization of sounds in the auditory field contralateral to the lesions. Bilateral lesions of the medial geniculate body produce a less dramatic deficit in which the animals are only mildly impaired on two-choice sound localization when the loudspeakers are centered around the animal's midline with a more severe deficit appearing when both speakers are placed to the left or right of the animal. However, if the lesions extend into the brachium of the inferior colliculus, the animals may be completely unable to localize sound. Finally, experiments with opossums, the domestic rat, and feral pack rats have indicated that cortical ablation may not have a dramatic effect on sound localization in all mammals. [Work supported by NIH.]

Effects of unilateral lesions of auditory cortex on brain stem thresholds for electrical stimulation

Data are presented from a total of 28 electrodes which were permanently implanted in six cats in cochlear nucleus, medial geniculate body, and nonauditory loci. Behaviorally measured detection thresholds for electrical stimuli applied through the electrodes were obtained prior to and after unilateral ablation of auditory cortex. The principal results were that detection thresholds were elevated after the lesion for 7 of 11 placements in the medial geniculate body, for three of nine placements in the cochlear nucleus or cochlear nerve root, and for none of the placements in the visual system. The threshold increases for four of the medial geniculate electrodes could be accounted for in terms of retrograde degeneration in the vicinity of the electrode tip. Other threshold increases, particularly those for placements in or near the cochlear nucleus, are interpreted in terms of a functional disturbance in the auditory system that resulted from the cortical lesion.

Effect of unilateral lesions of auditory cortex on reaction time to auditory stimuli of varying duration

Effect of unilateral lesions of auditory cortex on reaction time to auditory stimuli of varying duration

CONDITIONED REFLEXES ELICITED BY ELECTRICAL STIMULATION OF THE BRAIN IN MACAQUES.

ArticlesCONDITIONED REFLEXES ELICITED BY ELECTRICAL STIMULATION OF THE BRAIN IN MACAQUESRobert W. DotyRobert W. DotyPublished Online:01 Jul 1965https://doi.org/10.1152/jn.1965.28.4.623MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByLearning to Recognize Visual Objects With Microstimulation in Inferior Temporal CortexKeisuke Kawasaki, and David L. Sheinberg1 July 2008 | Journal of Neurophysiology, Vol. 100, No. 1Psychophysics of Electrical Stimulation of Striate Cortex in MacaquesJohn R. Bartlett✠, Edgar A. DeYoe, Robert W. Doty, Barry B. Lee, Jeffrey D. Lewine, Nubio Negrão, and William H. Overman1 November 2005 | Journal of Neurophysiology, Vol. 94, No. 5Laminar Variation in Threshold for Detection of Electrical Excitation of Striate Cortex by MacaquesEdgar A. DeYoe, Jeffrey D. Lewine, and Robert W. Doty1 November 2005 | Journal of Neurophysiology, Vol. 94, No. 5Visuotopic Mapping Through a Multichannel Stimulating Implant in Primate V1D. C. Bradley, P. R. Troyk, J. A. Berg, M. Bak, S. Cogan, R. Erickson, C. Kufta, M. Mascaro, D. McCreery, E. M. Schmidt, V. L. Towle, and H. Xu1 March 2005 | Journal of Neurophysiology, Vol. 93, No. 3Phosphene Induction and the Generation of Saccadic Eye Movements by Striate CortexE. J. Tehovnik, W. M. Slocum, C. E. Carvey, and P. H. Schiller1 January 2005 | Journal of Neurophysiology, Vol. 93, No. 1Behavioural state affects saccades elicited electrically from neocortexNeuroscience & Biobehavioral Reviews, Vol. 28, No. 1Behavioural state affects saccadic eye movements evoked by microstimulation of striate cortexEuropean Journal of Neuroscience, Vol. 18, No. 4Saccadic eye movements evoked by microstimulation of striate cortex13 February 2003 | European Journal of Neuroscience, Vol. 17, No. 4Perceptive properties of the multi-site electrical microstimulation of the olfactory bulb in the ratBehavioural Brain Research, Vol. 21, No. 1Excitation of visual cortex neurons by local intracortical microstimulationExperimental Neurology, Vol. 81, No. 2Intracortical microstimulation of neurons in the visual cortex of the catElectroencephalography and Clinical Neurophysiology, Vol. 52, No. 4Activation of single cells in cat visual cortex by electrical stimulation of the cortical surfaceExperimental Neurology, Vol. 70, No. 1Effects of unilateral lesions of auditory cortex on brain stem thresholds for electrical stimulationExperimental Neurology, Vol. 65, No. 3Relationship of the corpus callosum to visual areas I and II of the awake rabbitExperimental Neurology, Vol. 57, No. 2Discriminative control of behavior by electrical stimulation of the dorsal raphe nucleus: generalization to lysergic acid diethylamide (LSD)Brain Research, Vol. 86, No. 1Is frequency information extracted from electrical stimulation of the auditory system?Experimental Neurology, Vol. 43, No. 1Photically oriented conditioned reflexes elicited by electrical stimulation of the visual system in the catBrain Research, Vol. 51Increases in the cat's sensitivity to electrical brain stimulationPhysiology & Behavior, Vol. 7, No. 5Behavioral measurement of electrical stimulation thresholds for medial geniculate nucleusExperimental Neurology, Vol. 31, No. 1Inferior collicular CS intensity effect on rabbit nictitating membrane conditioningPhysiology & Behavior, Vol. 6, No. 4Effect of tetanization and enucleation upon excitability of visual pathways in squirrel monkeys and catsExperimental Neurology, Vol. 30, No. 3Stimulus generalization and transfer of training in rabbits conditioned to electrical stimulation of lateral geniculate nucleusPhysiology & Behavior, Vol. 5, No. 8A safe and reliable method for temporary restraint of monkeysPhysiology & Behavior, Vol. 4, No. 3A monkey chair for temporary restraint with minimal human contactPhysiology & Behavior, Vol. 4, No. 2Localization and habituation of sensory evoked DC responses in cat cortexExperimental Neurology, Vol. 15, No. 4 More from this issue > Volume 28Issue 4July 1965Pages 623-640 https://doi.org/10.1152/jn.1965.28.4.623PubMed14347624History Published online 1 July 1965 Published in print 1 July 1965 Metrics