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Cross Program Projects

Our Cross Program projects bring together researchers and students from across the various CCD research Programs, encouraging collaboration and innovation in cognitive science research. Some of these projects use advanced brain imaging techniques to better understand the time-course of brain responses to particular types of stimuli, such as words, sentences, pictures or faces. Several collaborative projects are supported through our internal Cross Program Support Scheme and Neural Markers Training Scheme.

Cross Program Projects

Neural Markers Projects

Cognitive-neuropsychiatric research on disorders of belief, person perception and memory

Robyn Langdon, Max Coltheart, Amanda Barnier and Emily Connaughton

The cognitive neuropsychiatric approach we adopt has two aims: first, to develop models of the normal cognitive processes involved in belief and memory and, second, to determine how well the models explain the profiles of psychiatric and related symptoms seen in individual patients. In recent research, we used a single case study approach with patients with misidentification delusions to investigate the normal system of person identity processing. This is a complex skill requiring integration of information from multiple sources, including face, voice and gait. Connaughton, Langdon and Coltheart have developed a battery of tasks to study unconscious processing of person identity using both face and voice cues. Our tasks assess unconscious processing of familiarity via changes in skin conductance and pupil size. This year, we have combined these tasks with tests of conscious person identification to study patients with Capgras delusion and other misidentification delusions. Another line of research, led by Barnier, is developing laboratory models of the transmission of beliefs based on memory paradigms that index the transmission of (true and false) knowledge. These techniques help us understand potential mechanisms and parameters of the social transmission of normal and abnormal beliefs.

Memory for faces

Fiona Kumfor, Rosalind Hutchings, Romina Palermo, Gillian Rhodes, John Hodges and Olivier Piguet

Our ability to perceive and recognise human faces occurs rapidly and with very little conscious effort, and is minimally affected by changes in physical characteristics such as age, appearance or expression. Individuals with dementia, however, often experience difficulty in recognising friends or family, or even famous individuals. We have conducted a series of experiments to better understand how face recognition is affected in dementia. This program of research aims to: inform models of face perception and face memory, determine how face recognition is affected across different dementia syndromes, and identify interventions that can improve face recognition in dementia. To achieve these aims, we are combining clinical neuropsychological tests with experimental tasks and eye-tracking technology. Our first study demonstrated that individuals with frontotemporal dementia are impaired at learning and recognising novel faces. Importantly, this deficit was associated with atrophy in the 'core' and 'extended' face processing network. We are currently investigating whether this deficit extends to familiar and famous faces.

Do I know you? Investigating prosopagnosia in left and right semantic dementia

Fiona Kumfor, Gillian Rhodes, Romina Palermo, Linda Jeffrey, Muireann Irish and Olivier Piguet

The ability to learn, remember and recognise faces is a complex ability, which is key to successful social interactions. Various cognitive stages are implicated, including early visual processing, face perception, and memory, however, the neural architecture supporting this ability remains unclear. This project investigates face recognition and memory in individuals with frontotemporal dementia, who show distinct patterns of atrophy in the frontal and temporal lobes. Using concurrent behavioural tasks and neurophysiological imaging, the study has so far investigated dissociations between covert and overt face recognition in more than 20 patients with frontotemporal dementia, and 15 healthy controls. Our findings reveal that individuals with frontotemporal dementia experience reduced ability to learn and recognise novel faces. Importantly, this is due to degeneration in neural regions that are critical for face perception, the fusiform gyrus and anterior temporal lobe. We are analysing the neurophysiological data, including heart rate and perspiration (skin conductance), to determine whether subliminal face recognition is also affected in these patients.

Understanding multiple components of self: Agency and body representation in healthy and impaired cognition

Vince Polito, Regine Zopf, Mark Williams, Amanda Barnier, Robyn Langdon, James Moore and Hannah Morgan

Our sense of agency is an integral part of our conscious experience and allows us to distinguish events or sensory consequences that we have caused from those that are have external causes. This project investigates how visual information about the position of an individual's body in space influences a person's sense of agency. In the experiment, participants completed two agency measures. One was an intentional binding task, which is a behavioural paradigm that indirectly assesses sense of agency by recording participants' perceived timing of self-generated actions. The second was a Sense of Agency Rating Scale, a questionnaire that records participants' explicit judgments of agency. Participants completed these tasks either with their body movements visible or hidden. We found that visual information about body representation strongly influenced participants' timing judgments and agency attributions. When visual information was absent, participants' timing judgments and agency attributions depended much more on internal cues, such as their predictions and expectations about their body movements. Another study explored the influence of specific body representation signals on sense of agency. Participants viewed a 2D digital representation of their hand movements as we systematically manipulated the features of the visual display. We found that spatial congruency strongly influenced participants' timing judgments and agency attributions, but that visual realism had less impact. Overall, the research findings show that sense of agency is a multidimensional construct that depends on a variety of external cues and internal signals, and that these cues are differentially weighted depending on the information available at any given time.

Exploring the role of meditation in language remediation: A behavioural and neurophysiological study

Britta Biedermann, Genevieve McArthur, Greg Savage, Yatin Mahajan, Peter de Lissa, Vince Polito, Lena Quinto, Michael Connors, Nicholas Badcock and Linda Larsen

Previous research with typical adults has shown that meditation can improve behavioural and neurophysiological indices of auditory attention. In two studies, we investigated the effect of meditation on spoken language via auditory attention measures (neurophysiological and behavioural). One phase of the project tested the auditory attention in 16 meditation experts (including Buddhist nuns and monks) and 16 novices using event-related potentials, in a meditative and a non-meditative condition. We found a qualitative difference between meditators and novices. The second phase tested healthy novices who participated in 8 weeks of meditation training, to see if their brain responses would become similar to those of long-term meditators over the training period. As compared to novices, long-time meditators were found to have a larger N100 response to sounds regardless of their meditative state. The results of the second phase of the project are being analysed to establish whether or not training auditory attention is successful. If so, we will conduct a further study to look at the improvement of auditory attention following meditation training in elderly individuals with and without stroke.

When FORM becomes FROM: Inducing Letter Position Dyslexia in the laboratory

Anne Castles, Paul Sowman, Saskia Kohnen, Greg Savage, Naama Friedmann and Yvette Kezilas

Letter Position Dyslexia is characterised by an extreme number of anagram errors, such as reading the word 'form' as 'from'. Recent work with adults who have acquired brain injuries to the right intraparietal sulcus (rIPS) has shown that they too make many anagram errors, leading to the hypothesis that the source of Letter Position Dyslexia may be a dysfunction in the rIPS. The present study used transcranial stimulation to investigate the role of rIPS in letter position coding. By investigating the role of rIPS in letter position coding, we hoped to gain a better understanding of the neural mechanisms that may be impaired in children and adults with Letter Position Dyslexia. Our first experiment used repetitive transcranial magnetic stimulation (rTMS) to temporarily inhibit activity in the cortical region comprising the rIPS in an attempt to temporarily induce symptoms typical of individuals with Letter Position Dyslexia. Specifically, we expected that participants would make more anagram errors on a visual lexical decision task by accepting the nonword 'cholocate' to be a word when rTMS was applied to the rIPS compared to when it was applied to a control site (vertex). For this study we found no effect of site stimulation on lexical decision performance. Our second experiment used transcranial direct current stimulation (tDCS) to temporarily facilitate activity in the cortical region, comprising the rIPS. We used the same lexical decision task as was used in our first experiment, as well as an additional lexical decision task where each target word was preceded by a briefly presented prime, such that the target word 'CHOCOLATE' is preceded by the prime 'cholocate'. While we found no effect of tDCS on the lexical decision task used, we found a small effect of tDCS on the masked priming task.

Gaze processing and referential and paranoid delusions in schizophrenia

Robyn Langdon, Gillian Rhodes, Linda Jeffery, Andrew Calder, Jonathan McGuire, Kiley Seymour and Colleen Murphy

A key skill in social situations is the ability to interpret where others are looking. This skill depends on the accurate perception of the direction of another person's gaze. People with schizophrenia tend to misperceive other people's averted gaze as directed towards themselves. People with schizophrenia are also expected to show reduced orienting to the averted gaze-signals that they misperceive as directed towards themselves. Moreover, the degree of gaze-perception bias should predict the extent of reduced gaze-orienting. However, previous studies of gaze perception in schizophrenia have typically asked participants to judge whether eyes in an image of a face are looking straight at them or away. Such an approach does not allow one to quantify the 'arc' of gaze-deviation misperceived as direct in order to examine associations between gaze-orienting performance and symptomatology, such as referential/persecutory delusions. To overcome the limitations of previous research, this project used the 'cone-of-gaze' (COG) paradigm to manipulate angles of averted gaze-signals, in order to quantify individual participants' arc of gaze-deviations misperceived as direct in people with schizophrenia and controls. We also developed a novel gaze-orienting task that used the same averted-gaze images as in the COG task. Preliminary analysis shows a clear cone-of-gaze in both groups with no evidence of a group difference. This suggests that previous evidence of gaze-perception bias in schizophrenia reflects a top-down effect that is manifested when self-referential instructions are used, 'Are the eyes looking at you?'. In contrast, our neutrally worded instructions 'Are the eyes looking left, right or direct?', showed an absence of any bottom-up misperception of averted-gaze signals in people with schizophrenia. Preliminary results for the gaze-orienting task are consistent with that interpretation: both groups showed equivalent reflexive effects of gaze-orienting, but only for angles of gaze-deviation appropriately perceived as averted in the COG task.

Using eye-tracking to measure orthographic and semantic learning after vocabulary training

Danielle Colenbrander, Peter de Lissa, Hua-Chen Wang, Anne Castles and Lyndsey Nickels

Vocabulary training can improve reading comprehension. However, if both the meaning (semantics) and the written form (letters or orthography) of words are trained, vocabulary training could potentially affect reading comprehension in more than one way - either by improving knowledge of word meanings, or by improving the ability to read the words, or both. It is important to understand how vocabulary training influences reading abilities, as this could influence teaching practice and inform theories of reading comprehension. Nevertheless, the only studies that attempted to disentangle the effects of vocabulary training at a fine-grained level have used offline measures of vocabulary learning which tell us what people know after vocabulary instruction but not how this new knowledge is applied in reading. This study developed real-time or online measures of the effects of vocabulary training on reading comprehension. We were particularly interested in whether showing participants the written forms of words during training helped them to better learn word meanings. Participants were taught twelve real, but unfamiliar English words (the names of obscure musical instruments, such as 'charango'). One group of adults was taught the meanings of the words along with their written form (orthography-present). The other group was taught the meanings without their written form (orthography-absent). We then measured their learning of word meanings offline using a multiple choice definition task, and assessed their ability to spell the trained words. We also measured online processing by tracking participants' eye movements while they silently read sentences containing the trained words. Preliminary findings indicate that the orthography-present group were better able to spell the trained words, and also read the trained words faster in the eye-tracking task, showing that they were able to apply their new word knowledge to the process of reading. However, there was no indication that the presence of orthography affected semantic learning in either the offline or online tasks. This is unexpected given that the presence of orthography during training usually leads to better semantic learning in children.

Use of tense in past and future contexts

Muireann Irish, Stephen Crain, Rosalind Thornton, Blake Johnson, Donna Rose Addis and Olivier Piguet

Language forms a cornerstone of human cognition, yet few studies have investigated what linguistic constructions can reveal about the underlying processes of episodic memory. Recent research showed that the tense used during past recall conveys immediacy in an event and correlates with hippocampal integrity. Here, researchers in the Memory and Language Nodes of the CCD will investigate the use of the historical present within past and future narratives in healthy aging and frontotemporal dementia. This project will elucidate how damage to the language networks of the brain impinges on the capacity for past and future thinking. We are now exploring the brain structures critical for future thinking in these syndromes using brain-mapping techniques.

Enculturated cognition and its disorders

Richard Menary, John Sutton, Max Coltheart, Nicolas Bullot, Greg Downey (Macquarie University), Doris McIlwain (Macquarie University), Evelyn Tribble (University of Otago, New Zealand), Regina Fabry (Johannes Gutenberg University of Mainz, Germany), Mirko Farina, Jan (Richard) Heersmink and Kellie Williamson

The main goal of this research is to theoretically and empirically examine the effects that cultural practices, tools and systems of representation have on cognitive mechanisms, encompassing four sub-projects:

Narrative, Belief and Theory of Mind: This research relates to the Belief Formation and Memory Programs, and here the main goal is to distinguish the role that narratives play in social cognition, especially theory of mind and disorders of the self. Research questions include: What is the role of narrative in confabulation? How do narratives influence the sense of self? What are the mechanisms responsible for narratives in these cognitive contexts? Is there a narrative route in the dual factor theory of delusion?

Cognitive Practices: This research broadly relates to the Reading Program and explores the notion that humans have shown a remarkable capacity to invent cognitive tools that capitalise on the environment. The main research question is: What are the various ways in which such tools transform our fundamental cognitive mechanisms and cognitive skills? Humans have only very recently (in evolutionary terms) developed writing systems for language and mathematics. The abilities to read and write and perform complex mathematical calculations are not evolutionary endowments. There are no neural circuits that have evolved specifically for reading and writing and there is no neural module for algebra; yet humans are capable of learning to read and write and solve algebraic equations. How is this possible? The project will develop a theoretical model of how the enculturation of the brain gives rise to a transformed set of cognitive systems that make reading, writing and mathematical cognition possible.

Mindful Bodies in Action: Skilled experts in sport or dance perform extraordinary actions in perfect time, with exquisite control, and display resilience whilst under pressure: their mindful bodies blend cognition and emotion in action. This research project integrates disconnected research on skilled movement in a new, multidisciplinary, mixed method account of embodied intelligence. Our studies focus on three sets of issues, concerning a) timing and anticipation; b) control and agency; c) resilience, personality, and pressure.

Cognitive History: This research builds a detailed framework for the historical study of cognition, incorporating cognitive approaches to cultural history and to literature, performance and the arts. One strand addresses ecologies of skill and memory in early modern England, integrating the theory of distributed cognition with detailed case studies of practices of memory, education, action, and religion in the 16th and 17th centuries. Another strand develops a psycho-historical theory of art history and aesthetics.

Belief in memory

Amanda Barnier, Donna Rose Addis (University of Auckland, New Zealand), Greg Savage, Rochelle Cox, John Sutton, Nicolas Bullot, Celia Harris, Muireann Irish, Emily Connaughton, Aline Cordonnier, Amanda Selwood, Marie (Misia) Temler, Kellie Williamson, Paul Keil and Aleea Devitt (University of Auckland, New Zealand)

The project brought together investigators from the Belief Formation and Memory programs to consolidate individual cross-program links into broader, long-lasting collaborations on Belief in Memory. We conducted a conceptual review of the relationship between belief and memory; conducted new experiments on the transmission of beliefs and memories via collaboration; and adapted memory-coding methods from Donna Addis and the Collective Memory team to examine the nature of remembering within clinical cases of delusional beliefs. We also are underway on a new sequence of collaborative recall experiments funded by recently awarded ARC Future Fellowship and Discovery grants. We found that beliefs, not just memories, can be transmitted when people collaborate together on tasks, developing new beliefs that they carry away from the group with them. And we found that people with clinical delusions use a lot of "memory talk" in service of their delusion but that the qualities of these memories look quite different from the memories of healthy people in autobiographical memory studies. The project also provided an avenue for high quality supervision and mentoring to postgraduates and postdoctoral fellows across the programs.

Face perception, trust and paranoia

Ryan McKay, Max Coltheart, Robyn Langdon, Emily Connaughton and Gillian Rhodes

The present study combined techniques from behavioural economics and experimental psychology, with the symptom-focussed approach of cognitive neuropsychiatry, to explore the attentional concomitants and financial consequences of paranoia. 150 participants played a series of financially incentivised, computerised bargaining games ('trust games'). A subset of participants with high and low levels of non-clinical paranoid ideation later took part in a second series of games while we concurrently recorded eye-movements. Paranoid trustors transferred significantly less money to trustees than non-paranoid trustors. Moreover, paranoid trustors earned less money from the games and were more sensitive to different trustee poses, transferring less money to trustees posing with 'neutral' or 'untrustworthy' expressions than 'natural' or 'trustworthy' expressions. In the eye-tracking phase of the study we found that paranoid trustors spent less time looking at trustee faces on each trial. Finally, there was a trend for dwell time to mediate the effect of paranoia on trustor transfers. Our results validate the trust game as a useful paradigm for evaluating non-clinical paranoia, and indicate that paranoid individuals are relatively averse to looking at the faces of interaction partners in a context of risk, defaulting to a more cautious (and ultimately costly) interaction strategy.

Powering up the right hemisphere when words fail: Augmenting melodic intonation therapy (MIT) with non-invasive brain stimulation to treat impaired left-hemisphere function

William (Bill) Thompson, Paul Sowman, Greg Savage, Lyndsey Nickels and John Hodges

We investigated whether the right hemisphere can be engaged using MIT and excitatory repetitive Transcranial Magnetic Stimulation (rTMS) to improve language function in aphasic patients. Two participants (GOE and AMC) had chronic non-fluent aphasia. The treatment included an rTMS phase, which consisted of 3 treatment sessions that used an excitatory stimulation method known as intermittent theta burst stimulation, and a sham-rTMS phase, which consisted of 3 treatment sessions that used a sham coil. Each treatment session was followed by 40 minutes of MIT. A linguistic battery was administered after each session. After MIT and rTMS treatment, one participant (GOE) improved in verbal fluency and phrase repetition. However, the other participant (AMC) showed no evidence of behavioural benefit from this treatment. Post-treatment changes in neural activity were observed in both participants, in Broca's area in the left hemisphere and in the homologue to Broca's area in the right hemisphere. These case studies indicate that a combination of MIT and rTMS applied to the right Broca's homologue has the potential to improve speech and language outcomes for some people with post-stroke aphasia.

Memory and reading in children with temporal lobe epilepsy

Suncica (Sunny) Lah, Lyndsey Nickels, Anne Castles, Mary-Lou Smith and John Hodges

Children with temporal lobe epilepsy (TLE) are at risk of episodic memory impairments and reading difficulties. Recently, we found double dissociations between episodic and semantic memory in children with TLE (Smith & Lah, 2011). In adults with temporal lobe pathology, semantic (but not episodic) memory impairments are associated with a selective loss of reading skills: surface dyslexia. In children with TLE, whose brain connectivity and cognitive skills are developing, specific cognitive impairments could interfere with development of other cognitive skills. This project investigates whether, unlike in adults, specific memory deficits in children are associated with pervasive rather than selective reading impairments.

Influence of language experience on the cortical representation of pitch: Comparison of MEG and EEG data

Ravi Krishnan (Purdue University, USA), Graciela Tesan and Blake Johnson

Neural representation of pitch at the brainstem level has shown that native speakers of Mandarin (compared to native speakers of English) show more accurate pitch tracking and stronger pitch representation of sounds with native pitch contours presented in either a speech or a non-speech context. These results suggest long-term language-experience-dependent reorganisation in the brainstem to enhance behaviourally relevant pitch contours in Chinese listeners. Here we examine whether this enhanced representation of pitch is also observed at the early sensory level processing in the auditory cortex using the cortical pitch response, recorded using concurrent magnetoencephalography (MEG) and electroencephalography (EEG) recordings, which presumably reflects pitch relevant neural activity localised to the lateral Heschl's Gyrus. The overall objective is to understand how language experience shapes pitch mechanisms in the brainstem and auditory cortex and also the nature of the interplay between cortical and subcortical pitch mechanisms.

MEG study of auditory change detection

Fabrice Bardy (The HEARing CRC), Shu Hui Yau and Blake Johnson

EEG and MEG studies of auditory perception in disorders such as autism, schizophrenia, language impairment, and dyslexia typically focus on the mismatch negativity response. Participants hear a sequence of identical "standard" sounds containing occasional "deviant" sounds. The mismatch negativity is calculated by subtracting the brain response to standard sounds from responses to the deviant. Unfortunately, the mismatch response is not particularly reliable, so it is not suitable for measuring differences between individuals. EEG has been used to measure a brain response, known as the Acoustic Change Complex, to subtle changes within rapidly presented sounds. This is more reliable than the mismatch response and provides a more direct measure of auditory change detection. We have conducted an equivalent MEG study. Preliminary results indicate that the rapid Acoustic Change Complex can also be detected using MEG. In comparison to EEG, MEG provides much clearer differentiation of responses originating in the left and right hemispheres of the brain.

MEG studies of auditory processing in autism

Jon Brock, Shu Hui Yau, Yatin Mahajan and Blake Johnson

Atypical auditory processing is a common feature of autism. Many individuals show hypersensitivity to auditory stimuli and some have exceptional pitch discrimination skills. There is also evidence, both from first-hand accounts and from experimental studies, that autistic individuals often have difficulty processing sounds in complex acoustic environments, particularly with regard to following speech against a noisy background. None of these features are incorporated in diagnostic criteria, but the fact they are nevertheless associated with autism indicates that there is, at some level, a causal relationship between atypical auditory perception and the "core" diagnostic symptoms of the disorder. Understanding the underlying neurocognitive mechanisms of atypical auditory perception should therefore provide important insights into the origins of autism. In one study, MEG was used to investigate auditory brain responses in a group of 10 autistic children, aged between 8 and 12 years. The stimuli used were noise bursts presented to both ears. On some trials, a timing difference was introduced between the two ears, leading to the illusory perception of a tone. For typically-developing children, the brain responses to the illusory tone began around 250 milliseconds after its onset. We predicted that autistic children would not respond to the tone at all, but in fact they showed an early response, at around 50 milliseconds, which has not previously been found in any other group.

Neural mechanisms of inhibitory control of vocalisation in aging and dysfluency

Andrew Etchell, Paul Sowman and Blake Johnson

As human beings we rely on speech as the most effective and flexible means of communicating our ideas and sharing our experiences and knowledge. During conversation the speech control system precisely coordinates nearly 100 muscles to produce 6 syllables per second. To achieve this, a delicate balance must be struck between excitatory impetus and inhibitory suppression so that the onsets and offsets of speech are both rapid and flexibly controlled. A significant role is played by mechanisms of executive control that allow the speaker to decide on one course of verbal action rather than another and rapidly select between competing speech motor plans. A central component is the capacity to inhibit initiated speech at almost any point in the production process. A clear understanding of the neural mechanisms of response inhibition in general is yet to be established. Furthermore, the underpinnings of response inhibition in the vocal domain are virtually unknown. This project is using MEG to elucidate the neural mechanisms that support vocal response inhibition and is examining how these mechanisms are affected in aging and by disorders of fluency such as stuttering.

Auditory processing in dyslexia

Blake Johnson, Genevieve McArthur, Michael Hautus (University of Auckland, New Zealand), Melanie Reid, Jon Brock, Anne Castles and Stephen Crain

This project examined central auditory processing in typically-developing readers, and in children with dyslexia. The main finding was that children with dyslexia showed less brain lateralisation of auditory cortical function as compared to typically-developing readers. The study recorded brain responses by both groups of children using EEG and MEG concurrently. There were 16 children with dyslexia aged 8-12 years, and an age-matched group of 16 children with normal reading ability. Auditory brain responses were elicited using sounds that were designed to engage binaural auditory mechanisms. We found that cortical processing of binaural information was associated with an auditory brain response at a latency of about 250 to 500ms. Typically-developing children and children with dyslexia showed no significant difference in the binaural response. However, the children with dyslexia showed less lateralisation of auditory cortical functioning, and a different pattern of development of auditory lateralisation with age.

Speech in the brain in developmental stuttering

Paul Sowman, Blake Johnson, Elisabeth Harrison and Stephen Crain

Deviations from the normal brain asymmetry of language function have been proposed to underlie speech/language dysfunctions, one of which is stuttering. In the 1920s Orton developed the concept of stuttering as a manifestation of incomplete cerebral dominance for speech. His theory was that in the presence of incomplete hemispheric dominance, the initiation of speech proceeds concurrently in both hemispheres causing the resultant motor output to be incoherent or stalled by interhemispheric inhibitory processes. However, until recently, the ability to non-invasively measure the lateralisation of speech function in children has not been possible and therefore direct examination of this hypothesis had not been tested. We are currently measuring brain activations during speech production in children who stutter around the time of stuttering onset (2-5 years) using MEG.

Development of face perception

Blake Johnson, Jon Brock and Wei He

Some investigators maintain that full maturation of the abilities to perceive faces occurs as late as adolescence, while others suggest that it happens much earlier in the preschool years. In support of the late development hypothesis, recent neuroimaging studies have reported that an adult face-specific brain response is absent in children. However these researchers used adult sized brain imaging systems, which are not optimal for measuring brain activity from the much smaller heads of young children. This project has examined the question of when face perception attains adult capacities by measuring face-specific responses in pre-schoolers aged 3-5 years, using the unique child MEG brain imaging system at the CCD, which has been custom-built for use with pre-school aged children. The results of this project show that the face-specific brain response is present and functional in children aged 3-5 years. However, the functional interactions of the components of the brain network that underlie the face-specific brain response in children have not yet reached adult patterns of organization and functionality.

Engaging children in brain imaging research

Blake Johnson and Wei He

The preschool years are a period of dramatic development of brain function, but there has been relatively little study of children in this age range with modern brain imaging techniques. One reason for this is that children have limited abilities to constrain head and body movements, and attend to experimental stimuli for the extended periods of time required to acquire recording of brain activity. This year, we completed construction of an MEG simulator, to provide a simulated MEG environment in which we can train children in the experimental protocols that are used in the magnetically shielded room that houses our customised paediatric MEG system. Using the simulator will significantly improve the amount and quality of data that can be recorded from young children.

MEG studies of motor control in children

Blake Johnson, Douglas Cheyne (University of Toronto, Canada), Cecilia Jobst (University of Toronto, Canada), Rita Al-Loos (University of Toronto, Canada), Huizhen Tang (Albert Einstein College of Medicine, USA), Wei He and Stephen Crain

Speech is arguably the most complicated action that humans perform, yet is acquired with apparent ease in the preschool years. The brain mechanisms of speech motor control have rarely been studied in children due to methodological and technical challenges. We are addressing these challenges by recording motor cortical function in young children using MEG. Cortical oscillations in children's motor cortex suggest previously undocumented developmental changes in the organisation of their cellular generators. Our studies of motor control of manual movements have revealed significant differences in the timing and polarity of movement-related MEG fields in preschool age children, as compared to adults, showing that maturation of the motor system is incomplete in the late preschool years and undergoes significant transitions after the age of 5 or 6 years. A follow-up study of the same children two years later revealed a transition towards adult-like event-related movement fields and increased adult-like high gamma oscillations. This suggests that there are functional changes in cortical motor circuits during early childhood that impact both motor field components and the frequency, or 'tuning', of oscillatory activity in the same brain location. While current work focuses on motor control of manual movements, this project sets the stage for new methods and technologies that will allow us to image the brain activities that control speech movements in young children. The results will help explain why speech is acquired effortlessly and rapidly by typically developing children, and why acquisition is more problematic and protracted in children with language impairments.

Measurement of hippocampal theta rhythm in aged adults

Blake Johnson, Brian Cornwell (Swinburne University of Technology) and Yi Pu

The hippocampal formation is a brain region that is affected early and prominently in Alzheimer's disease and other dementias, and the learning and memory functions mediated by this structure are the earliest and most severely affected by dementia. The hippocampal theta rhythm is a conspicuous oscillation of neuronal or brain activity first discovered in the rat brain and recently shown to be detectable from the human brain using non-invasive MEG brain imaging. This opens a new opportunity for the development of highly sensitive and clinically applicable methods to study how and when the function of the hippocampal formation is affected in Alzheimer's disease, other dementias, and in normal aging. Since the theta rhythm is a dominant operational mode of the hippocampus, we hypothesise that changes taking place in the brain during the development of Alzheimer's disease will be reflected by changes in the theta rhythm at the very earliest stages of the disease.

Using MEG to identify the brain regions involved in slow motor performance in preschool children who stutter

Paul Sowman and Oren Civier (Bar-Ilan University, Israel)

Stuttering is a pervasive developmental speech/language disorder, which affects approximately one percent of the adult population. Neural network simulations suggest that stuttering results from a general slowness of the motor system, but it is unknown which brain regions contribute to the slowed performance. The goal of the proposed study is to use MEG to investigate motor cortical activation in young children who stutter, before they develop compensatory strategies. The findings will advance our understanding of the development of speech production networks in the healthy and stuttering brain. These advances may eventually contribute to the development of effective therapy strategies and imaging-based therapy assignment.

Reading acquisition in the brain: An MEG study of sight word learning

Hua-Chen Wang, Paul Sowman, Peter de Lissa and Anne Castles

When encountering a written word for the first time, a child needs to first map each letter onto its respective sound (phonological decoding). Within a few exposures, the child can then rapidly recognise the word without having to decode it again. This transition, from laboriously sounding out the letters in a novel word to automatically recognising the word, is referred to as learning to read by sight, and it is essential for proficient reading. To better understand how this skill is achieved, this project will use MEG to explore neural activation simultaneously as children and adults learn new words. This project will address an important question that remains largely unanswered: how does one move from effortfully sounding out unfamiliar words to reading words by sight? The outcomes will directly inform models of both the skilled reading system and of reading acquisition, which is relevant to the further development of theories of the cognitive systems involved in reading. Participants in this study were exposed to novel words and familiar words over four repetitions, and their brain responses were recorded using MEG. Preliminary analyses comparing the first exposure of familiar and novel words showed that novel words elicited greater neural activity (M170) in the visual word form area compared to familiar words. Further, comparing activation over four exposures, novel words showed degraded activity over each exposure whereas familiar words showed no difference in activation over subsequent exposures. This study was the first to use MEG to investigate word learning in real time. Preliminary analyses showed a neural correlate for the process of rapid acquisition of new orthographic representations.

The effect of emotion on perception and memory

Thomas Carlson, Brianna Kennedy and Steven Most

Emotional context can impair the perception of subsequent stimuli, an effect known as 'emotion-induced blindness'. Previous neuroimaging work suggests that emotional images can also impair the neural signals for items that come soon after them. This project seeks to understand if emotional images that appear before a target item may similarly impair the ability to categorise that item. The project uses MEG and decoding methods. We are interested in the neural signature for categorising items that come before and after the emotional stimuli.

Contributions of frontal and temporal lobe structures to facial emotion recognition: An MEG study in frontotemporal dementia

Fiona Kumfor, Wei He, Olivier Piguet and Blake Johnson

Individuals with frontotemporal dementia show a profound loss in their ability to understand and interpret social information. To date, much of the research has focused on patients' difficulty in identifying the meaning of different facial expressions, such as an angry face or a sad face. This project investigated why this breakdown occurs using MEG. In healthy people, it has been well established that the brain produces a specific signal when viewing faces, which occurs less than 200 ms after seeing a face. Moreover, differences in the signal pattern of this face-sensitive response can be observed depending on the type of emotion a person is viewing. In this project we are measuring MEG brain signals while participants view faces with different types of emotions, including anger, disgust, and sadness, as well as viewing objects like different types of cars. Participants include a group of people with frontotemporal dementia and a group of healthy older adults. Preliminary analyses indicate that individuals with frontotemporal dementia show reduced and asynchronous MEG responses when viewing emotional faces. It is envisaged that the results will help understand the cause of the pervasive social deficits in patients with frontotemporal dementia and may also serve as a novel way to detect the very early stages of the disease. The pilot data from this project formed the basis of a successful NHMRC-ARC Dementia Research Development Fellowship awarded to Kumfor.

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