Abnormal Auditory System Function In Schizophrenia: An ERP And MEG Study Of Its Origin, Course And Generality.
Funder
National Health and Medical Research Council
Funding Amount
$250,770.00
Summary
In 1991, an Australian group found that schizophrenia patients have a reduced brain response to deviant sounds in a repeating pattern of identical sounds. Deviant sounds produce a brain electrical response known as mismatch negativity which is generated by the auditory cortex in the brain's temporal lobes and by adjacent areas in the frontal lobes. A smaller mismatch negativity in patients has since been replicated in laboratories in the US, Europe and Australia. The importance of this finding i ....In 1991, an Australian group found that schizophrenia patients have a reduced brain response to deviant sounds in a repeating pattern of identical sounds. Deviant sounds produce a brain electrical response known as mismatch negativity which is generated by the auditory cortex in the brain's temporal lobes and by adjacent areas in the frontal lobes. A smaller mismatch negativity in patients has since been replicated in laboratories in the US, Europe and Australia. The importance of this finding is that it had not been previously recognised that patients have low level auditory problems that could potentially have a profound impact on higher level functions. Finnish researchers have gone on to show in healthy individuals that mismatch negativity can reveal important features about how well the auditory system works, e.g., for the brain to respond to a deviant sound, it must have a memory of what happened in the past. Mismatch negativity provides a measure of the integrity of these memory functions. But it also provides an index of how well the auditory system discriminates different aspects of sound, pitch, loudness, and temporal features, such as duration. There are hints in our data and from US researchers that processing of the temporal features of sounds is particularly impaired in schizophrenia. We have also recently discovered that first-degree relatives of patients may have a similar deficit. The aim of this project is to use mismatch negativity to probe what is wrong with the auditory system in schizophrenia and those at risk (first degree relatives). Is it the areas of the brain primarily involved in sound perception (the temporal lobes) that are faulty or is the problem in the frontal lobes? Is it the case that processing of temporal features are particularly compromised and if so, is this a biological marker for schizophrenia. Answers to these questions will greatly enhance our understanding of the nature of the brain dysfunction in schizophrenia.Read moreRead less
The Neurobiology Of Auditory Hallucinations: Characterisation Of Dysfunction Within A Neural Circuitry Model.
Funder
National Health and Medical Research Council
Funding Amount
$299,625.00
Summary
This is a highly innovative research proposal which is based on years of extensive research by our group. Auditory hallucinations are a prominent and potentially disabling symptom of psychosis, however it is extremely difficult to study them scientifically. Past research by our group (and other groups internationally) has indicated that an extensive network in the brain is activated whenever auditory hallucinations occur, but the source of this brain activity is unclear. It was thought that the ....This is a highly innovative research proposal which is based on years of extensive research by our group. Auditory hallucinations are a prominent and potentially disabling symptom of psychosis, however it is extremely difficult to study them scientifically. Past research by our group (and other groups internationally) has indicated that an extensive network in the brain is activated whenever auditory hallucinations occur, but the source of this brain activity is unclear. It was thought that the source may be the same brain circuits that are involved in generating inner speech or monitoring it, but our past research has ruled out these possibilities. Instead, our recent work suggests that auditory hallucinations may be associated with poorly functioning connections within central auditory processing circuits, specifically between left and right auditory association cortical regions. We conceptualise hallucinations as an abnormal and involuntary form of memory retrieval consequent to this dysfunction. Our study will pioneer methods of measuring connectivity in the brain circuits identified in our model, using a combination of functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) techniques in tandem with tests of central auditory processing. We believe that sufferers may benefit from understanding the physical processes which cause hallucinations. We also believe that a better understanding of hallucinations may lead to a better understanding of schizophrenia and the psychoses, which may in turn help in the development of better ways of treating these illnesses.Read moreRead less
Episodic Memory Dysfunction As A Basis For Auditory Hallucinations In Schizophrenia
Funder
National Health and Medical Research Council
Funding Amount
$278,517.00
Summary
Auditory hallucinations (AHs) occur frequently in people who suffer from schizophrenia. This symptom usually involves hearing voices that the hallucinator firmly believes originate from other people. The voices are often intrusive, abusive and persecutory. They are a source of significant stress and may result in self harm or harm to others. Our investigations will attempt to provide experimental support for the theory that AHs represent a misremembering of voices which were heard in the past. W ....Auditory hallucinations (AHs) occur frequently in people who suffer from schizophrenia. This symptom usually involves hearing voices that the hallucinator firmly believes originate from other people. The voices are often intrusive, abusive and persecutory. They are a source of significant stress and may result in self harm or harm to others. Our investigations will attempt to provide experimental support for the theory that AHs represent a misremembering of voices which were heard in the past. We will do this by attempting to characterise specific problems that hallucinators have in identifying when they heard verbal fragments and who said them. We plan to conduct our investigations at five levels. First, we will determine how accurate hallucinators' memories are for context by the use of special neuropsychological tests. Second, we will find out if hallucinators form more false memories than comparison subjects using a test in which such incorrect recollections occur commonly. Third, we will determine if hallucinators have a tendency to reconstruct the characteristics of false verbal memories in the same way that they reconstruct the characteristics of their hallucinations. Fourth, we will attempt to suppress these false verbal memories and finally, we will characterise those brain regions which are activated during true and false memory formation by using blood flow analysis technology in order to identify networks of brain activity which preferentially malfunction in hallucinating patients. This study provides the prospect of adding substantially to our understanding of the mechanisms underlying auditory hallucinations and to lead to the development of new cognitively-based treatments for the symptom.Read moreRead less
Examining The Contribution Of The Mirror Neuron System Toward Social Cognitive Impairment In Autism Spectrum Disorders
Funder
National Health and Medical Research Council
Funding Amount
$149,154.00
Summary
Despite a rapidly increasing prevalence, our neurobiological understanding of autism and Asperger's disorder remains limited. Using modern neuroscience techniques, this study investigates whether dysfunction within a specific brain cell, the mirror neuron, underlies social and language impairments in these disorders. This research provides exciting new directions for the understanding, diagnosis, and potential treatment of autism and Asperger's disorder.