Leave a comment

Dependencia-independencia de campo y diferenciacion hemisfén’ca en tareas de escucha dicotica. Estudios de Psicologia, 23/24, Gilbert, C., & Bakan. Aproximación a la construcción de un test de escucha dicótica en población mexicana: definición de los parámetros relevantes para los estímulos y pilotaje en. Test de escucha dicótica en español: pares de palabras bisilábicas. Do you want to read the rest of this article? Request full-text. Request Full-text Paper PDF.

Author: Salkis Kimi
Country: Rwanda
Language: English (Spanish)
Genre: Finance
Published (Last): 28 January 2015
Pages: 259
PDF File Size: 13.9 Mb
ePub File Size: 11.75 Mb
ISBN: 116-9-26604-464-1
Downloads: 50004
Price: Free* [*Free Regsitration Required]
Uploader: Kajit

Login Register Login using. You can login by using one of your existing accounts.

We will be provided with an authorization token please note: This means that you will not need to remember your user name and password in the future and you will be able to login with the account you choose to sync, with the click of a button. Suggest a Research Topic. Left temporal lobe structural and functional abnormality underlying auditory hallucinations escucya schizophrenia.

In this article, we have reviewed recent findings from our laboratory, originally presented in Hugdahl et al. An overview of diagnostic questionnaires for scoring of symptoms is presented together with a review of behavioral, structural, and functional MRI data. Functional imaging data have either shown increased or decreased activation depending on whether patients have been presented an external stimulus during scanning.

Structural imaging data have shown reduction of grey matter density and volume in the same areas in the temporal lobe.

We have proposed a model for the understanding of auditory hallucinations that trace the origin of auditory hallucinations to neuronal abnormality in the speech areas in the left temporal lobe, which is not suppressed by volitional cognitive control processes, due to dysfunctional fronto-parietal executive cortical networks. Also, it should be noted that the voices should have been present for more than escudha months. An auditory halucintion can therefore be dicotlca as a key symptom to diagnose schizophrenia.

Hallucinatory-like experiences are a core symptom in schizophrenia. An important distinction between psychotic and non-psychotic hallucinations is the attribution of the source of the voices. Non-psychotic individuals typically attribute their experiences to internal sources, while psychotic patients often attribute their experiences to external sources. Hence, to qualify as a symptom, hallucinations are typically attributed to coming from outside of the person.

Such an overlap would have consequences for current theories and models of schizophrenia in general, particularly for diagnostic categorization in psychiatry. Positive symptoms are unwanted thoughts and behaviors that are in excess and out of proportion of what could be considered natural or normal, for e.

Treatment for positive symptoms can help in reducing the frequency and intensity of such thoughts and behaviors. Negative symptoms, on the other hand, are behaviors that should be increased, e.

Treatment for negative symptoms is therefore aimed at increasing what is lacking rather than reducing what is in excess, as in the case of positive symptoms.

Currently, the different scales could be regarded as more or less interchangeable, when it comes to intra-class correlations, and having a shared factor structure Loas et al. All three symptom rating scales tap visual and other forms of hallucinations, although a score of high or extreme frequency of experienced hallucinations will be based on the existence of auditory hallucinations. In addition, there are two other sub-scales measuring emotional and behavioral responses to the voices.

The statements dicoticq BAVQ-R are phrased in dicotlca language that is common in diagnostic and therapeutic interviews and conversations.

Login using

Summary of the above-mentioned symptom scales is given in Table 1. In the following sections, an extended summary and review of dicotjca findings on auditory hallucinations that were originally presented as a regular Frontiers in Human Neuroscience article Hugdahl et al.

Here, an extension of the original findings, and also new data collected after the original esckcha was published, is given. This study aims to advance the understanding of the cognitive and neuronal underpinnings of auditory hallucinations in schizophrenia. The methodology considered is to use an experimental neurocognitive approach using an auditory dichotic listening task see the text below together with structural and functional MRI in patients experiencing auditory hallucinations.

The new findings revealed that hallucinating patients have problems in processing an external speech sound, particularly when experiencing ongoing hallucinations and also when instructed to use attention to better focus on the external stimulus. The phenomenon was paralleled in grey matter reduction in temporal lobe areas.

The significance of the findings is discussed with regard to a neurocognitive model for auditory hallucinations, emphasizing perceptual mis-representations caused by neuronal abnormality in the temporal lobe areas. Auditory hallucinations are also of interest from a psychological and neuroscience point of view as the patients may be as convinced that they hear a voice originating from outside of the person, as are healthy persons when they are actually spoken to. As the cortical localization and the neural pathways for speech sound perception are quite well dicltica out, not the least from recent functional neuroimaging studies Binder and Price, ; Hickok and Poeppel, ; Hugdahl et al.

Speech perception and production are lateralized to the left hemisphere, and localized to areas in the temporal and frontal lobes, respectively. Although more recent behavioral e.

  ASTM 2096 PDF

Hence, if auditory hallucinations have neuronal origin in the same areas as normal speech perception, the left superior and middle temporal gyrus and superior temporal sulcus would be prime candidates, connecting ventrally with anterior parts of the temporal lobe and frontal regions and dorsally with dictica regions see Figure 1.

ESCUCHA DICOTICA by Eba Tomé | Free Listening on SoundCloud

Outline of a model for auditory hallucinations AH as perceptual mis-representations, parietal lobe attention enhancement and failure of prefrontal executive suppression control.

The model emphasizes the involvement of the middle and superior temporal gyri 1 for the generation of AH, prefrontal cortex 2 for top—down executive control, and parietal cortex 3 for attention focus. The model presented in Figure 1 outlines a temporal-fronto-parietal neural circuit in which auditory hallucinations are considered as a bottom—up phenomenon that involuntarily attracts attention focus to the voices. Hence, the hypothesis is that auditory hallucinations are not kept in control, or inhibited, due to failure of prefrontal and anterior cingulate-mediated executive inhibition and response suppression.

Such a hypothesis is supported by the findings of Rund et al. The results dixotica that the schizophrenia group scored significantly lower as compared to a healthy control group and a group of depressed patients included as a clinical comparison group.

On the basis of the findings of Hugdahl et al. Such a view is also ducotica agreement with other studies on auditory verbal hallucinations, for e.

See also Woodruff for further discussion of the neuropsychology of auditory hallucinations. A mis-representation hypothesis could be tested in several ways, using neuropsychological tests and functional brain imaging measures, like fMRI. In addition, pathology of grey matter tissue in the same areas in the brain would support a view of auditory hallucinations as dicotca of neuronal activity, if it could be shown that hallucinating patients show reduced or altered brain tissue volume or density in the left temporal lobe.

We describe an experimental neuropsychological approach, together with structural and functional MRI measures in the following sections. In a neuropsychological study on auditory hallucinations, Green et al. Dichotic listening means that two different stimuli are presented simultaneously, one stimulus in the right ear and the escuvha in the left ear. The version of the dichotic listening procedure used in the laboratory consists of pair-wise presentations via headphones of simple CV syllables.

Due to the preponderance of the contralateral auditory pathways, a stimulus presented to the right ear will have direct access to the speech perception areas in the left temporal lobe, dcotica at the same time block the ipsilateral left ear stimulus input to this area Kimura, A typical finding in healthy individuals is the so-called REA which simply means that more correct items escucja reported for the right ear stimulus and would indicate that the hemisphere is dominant or specialized for speech perception and speech sound processing.

A preference for reporting the syllable presented in the right ear is expected due to the phonological features of the syllable and as the speech sounds are perceptually processed in the wscucha temporal lobe. Schematic illustration of the dichotic listening procedure in which two different consonant—vowel syllables are presented simultaneously, one syllable in the left ear and the other in the right ear.

In addition to the standard procedure, the paradigm can also be dicoticz to study attentional and executive control functions, similar as seen in the Stroop-task Lund-Johansen et al. The dichotic presentation mode produces a conflict situation when the subject is instructed to report only one syllable on each trial. Although a stimulus presented in e. The right ear syllable would have an initial unique access to the left hemisphere processing areas, thus causing a preferred right ear response from the subject.

Hence, the CV syllables in a dichotic listening situation would be ideal for the study of left temporal lobe abnormality in auditory hallucinations, by allowing comparison of percentage of correct reports for the right ear and left ear syllables across trials. The failure of patients with schizophrenia to show a REA would then indicate a left temporal lobe functional deficit or impairment. The findings of Green et al. An interesting extension of the dichotic listening method for revealing left temporal dysfunction in auditory hallucinations is the usage of a dichotic training procedure for improving the ability to ignore symptoms like hallucinations, and at the same time to improve other cognitive functions.

However, the results have varied, Fiszdon et al. The idea behind the usage of a dichotic procedure for training to inhibit or ignore voice symptoms is that the dichotic situation gives rise to a very strong response tendency to report the right ear stimulus. If the patient can be trained in an experimental situation to suppress responding to the stimulus heard in the right ear, instead of shifting attention to the less dominant left ear stimulus, it can be generalized to suppress attention to the voices in real life.

Frequent hallucinations almost always go together with other positive symptoms, like delusions, bizarre behaviors, and conceptual disorganization. In this review, new data related to the question whether other positive symptoms also correlate negatively with magnitude of the REA in the dichotic listening test is presented.


Table 2 gives correlations between dichotic listening laterality index scores and each of the 24 symptoms in the BPRS symptom questionnaire Ventura et al. Such an outcome would be predicted from a dicotoca that hallucinations originate in the left hemisphere speech perception areas, and is also consistent with the findings reported by Green et al.

In Table 2positive, not negative symptoms, correlate negatively with performance on the dichotic listening task, indicating a specific left temporal lobe deficit. Functional neuroimaging studies have measured, while placing in the MR scanner, either changes in blood flow or blood oxygen levels in patients during periods of hallucinations contrasted with periods of absence of hallucinations, or response to the presentation of external speech or other acoustic stimuli concordant with reports of hallucinations.

Monitoring of neuronal activation and blood flow occurring during hallucinations in the absence of external stimuli have in general shown increased activation in temporal lobe areas Dierks et al. In a mini-review, Sommer et al.

Functional neuroimaging studies that have used externally presented speech stimuli, or provided instructions to generate inner speech perceptions, when in the scanner, have resulted in decreased activation in excucha same brain areas in hallucinating patients compared to healthy controls Zhang et al.

The results are supported by ERP-studies e. Figure 3 shows fMRI activation data from the laboratory for patients experiencing frequent versus infrequent hallucinations. All subjects were presented with the dichotic CV ricotica when placed in the scanner.

As seen in Figure 3the hallucinating patients failed to activate the speech areas in the upper posterior part of the temporal lobe, and in particular on the left side.

Dichotic listening

In addition, the patients shown in Figure 3 also failed to show activation in the anterior cingulate cortex when instructed to focus attention and report only from the left ear in the dichotic listening situation. Figure 4 shows that the same patients failed to activate what could be called a generalized effort network when contrasting the images during the forced-left instruction condition with the images obtained during the forced-right instruction condition.

A generalized effort network would be activated whenever demands for recruitment of higher-order cognitive functions, like attention, working memory and executive, or control functions, are called for and would show activations in prefrontal cortex, anterior cingulate and inferior parietal cortex.

A generalized effort network would be activated orthogonal to the default mode or resting state network as suggested by Fox and Raichle Such a state is activated in the absence of explicit tasks or instructions and contains the medial frontal gyrus, middle temporal gyrus, pre-cuneus, and posterior cingulate cortex. As seen in Figure 4hallucinating patients fail in the recruitment of higher cognitive functions necessary for adequate top—down suppression and executive control. It is proposed that cognitive impairments in schizophrenia, including inhibitory control of hallucinations in addition to a temporal lobe abnormality, may involve failure of down-regulation of a resting-state network and corresponding up-regulation of an effort network, thus upsetting the normal functioning of cognitive control mechanisms.

The red ovals highlight the activation in the anterior cingulate cortex, which is a part of a proposed generalized effort network. The apparent contradicting findings with regard to functional neuroimaging, with both increased and decreased activation in hallucinating patients, can now be resolved within a single model.

Increased activation in the absence of external stimuli during hallucinations would be due to abnormal or spontaneous neuronal activity. Failure of a response to external speech or acoustic stimulus would be due to the neurons that are already engaged by an internally generated activity, thus showing a kind of neuronal refractory effect to external stimuli.

The fact that different mechanisms may be involved for left temporal lobe activation during spontaneous hallucinations and the absence of activation when hallucinating patients are required to process an external speech sound is supported by the findings of McGuire et al.

It is therefore suggested that auditory hallucinations elicit spontaneous neuronal activation in the left escucua lobe that blocks reception of speech stimuli when presented e. Such an explanation could then also accommodate the findings of increased neuronal activation in hallucinating patients in the absence of external auditory stimuli.

Structural MRI studies have confirmed abnormality in the speech areas in the left temporal lobe in patients with schizophrenia, with reduced grey matter density and volume on the left side compared to the right side e. In a recent meta-analysis of 17 studies, Williams showed that reduction in grey matter volume and density in the left superior temporal gyrus in patients with schizophrenia is the most consistently reported brain structural abnormality.

Interestingly, the left temporal lobe abnormality was also seen in first-episode patients, which would dscucha the above-mentioned argument that positive symptoms related to left hemisphere abnormality may be a cause, rather than a consequence, of the disorder.