About the Memory Theme
Research
Memory Theme Members
Student Mini-Conferences and Seminars
The Student Memory Theme consists of all graduate students whose research touches on the topic of "memory", and whose supervisors are members of the Memory Theme. The group is very active, with an annual mini-conference.
Photograph: Memory Theme Students attentively listen to a presentation by biochemistry student Sarah Webb at the student mini-convention.
2009 Memory Theme Students Symposium Report
The 2009 Memory Theme student function was held on Wednesday 14 October,
and was a very enjoyable evening for all involved. This year, instead
of holding the symposium in the afternoon followed by a dinner in the
evening, we trialled combining the two in order to minimise the time commitment
at this busy time of year, and I believe this arrangement worked very
well. We enjoyed a fantastic 3-course meal at Luna, with several students
presenting their research between each course. Each student spoke for
approximately five minutes and then fielded questions from the group.
Once again there were students at all different stages in their research, and a wide variety of topics – a surprise to many of the newer students! In total this year we had sixteen Masters and PhD students, 14 from the psychology department and 2 from Anatomy and Structural Biology. This is an improvement on last year, however I would like to see more students from outside of Psychology at future events, and I will endeavour to spread the word more widely in other departments to ensure that all eligible students are included on the mailing list. Once again, the student function was a huge success, and we are well aware of the very generous support of the Memory Theme. It is always a great opportunity to meet and socialise with other students in our field, as well as to learn more about memory research that is going on at Otago University. Thank you very much!
Kirsten Cheyne
Students were asked to provide a brief summary of their proposed research, or results to date. These are presented below.
Memory Theme Students’ Research Summaries
DEPARTMENT OF PSYCHOLOGY
Marthinus Bekker
Marthinus is studying towards a Masters with Dr Louis Leland, Jr.
New Zealand is rated the 7th highest country in the world for the prevalence of asthma, with an estimated 15.1% of the population suffering from this disorder. Contributing to the severity of the problem is the poor management of the condition despite the availability of adequate treatments. Patient compliance with asthma medication regimes is well known to be poor; the tertiary student population is a particularly noncompliant group with self-reported adherence being as low as 44%. Marthinus’s current study has three main aims, the first is to test a method of increasing asthma medication adherence, the second is to improve the technique which participants employ when using their inhalers, and the third is to make participants aware of the positive outcomes associated with reaching the other aims and provide them with general education. Marthinus is approaching these aims using proximal pairing, feedback, and education. Preliminary results show an increase in usage and better technique on average.
Kana Imuta
Kana is in the beginning stages of her PhD with Dr Harlene Hayne
Verbal reminders play a pervasive role in memory retrieval by human adults. For adults, relatively non-specific verbal information (e.g., “Remember the last time we ate at that restaurant?”) will often cue vivid recollections of a past event even when presented outside the original encoding context. At what point in human development do children begin to use another person’s general prompts to cue retrieval of a particular memory? Although many researchers have argued that the ability to use verbal retrieval cues represents a major hallmark in memory development (Hayne, 2004; Hudson, 1990), we know very little about the effect of verbal information on memory retrieval by young children. Our previous findings indicate that, at least by the age of 4 years, children are able to use another person’s language to remind them about a prior event (Morgan & Hayne, 2007). The overarching goal of the present experiment is to assess when, during development, children begin to use verbal retrieval cues to facilitate retention after a delay. Specifically, we will assess age-related differences in the effectiveness of this verbal reminder treatment on memory retrieval by 1- to 4-year-olds.
Jo Walker
Jo is doing her Masters project with Dr Harlene Hayne
Jo is doing research into infant memory development. It has previously been established that infants show different forgetting functions for different tasks. These tasks can become associated in memory if they occur in close temporal proximity and in the same context. Previous research has demonstrated that associating the memory of two separate tasks will extend the memory of the shorter-lived task to match the longer-lived task. Jo is investigating whether this finding can be replicated using two commonly used infant memory tasks. Her research aims to contribute to the investigation of changes in infant memory processing and to the puzzle of infantile amnesia.
Kenzie Gentle
Kenzie is doing Masters research with Dr Rachel Zajac
Kenzie is researching a simple technique to make eye-witness identification in the elderly more accurate. Eyewitness identification is persuasive but fallible. DNA exonerations have exposed mistaken identifications as the leading cause of wrongful convictions. Older adults are particularly likely to select a photo from a target absent lineup which can result in the incarceration of innocent members of society. Despite older adults being likely to witness crimes and be called on to act as a witness, research examining ways to improve eyewitness performance in this population has largely been neglected. The proposed study aims to extend the findings of Zajac and Karageorge’s study (2009) to determine whether the Wild Card, a simple technique found to be highly effective in improving performance on target-absent lineups in children, will produce similar effects in older adults. We will also examine some of the factors that may contribute to poorer performance in the elderly, including recall for instructions, memory self-efficacy, and the means by which they made their selection. Young and older adults will be shown 6 short films after which they will participate in a short distractor task. Following each distractor task, participants will be asked to identify the perpetrator from a target present or target absent lineup and will answer a few questions about their selection. Participants will be randomly assigned to a standard lineup condition or a lineup containing the Wild Card. It is hypothesised that the inclusion of the Wild Card, in an otherwise standard lineup, will improve accuracy on target absent lineups in the elderly participants. Results from this study may contribute to improving the conditions under which eye-witnesses provide their identifications.
Sumeer Chadha
Sumeer is completing a Masters project with Dr David Bilkey
Sumeer is examining the communication between the prefrontal cortex and the hippocampus during goal-directed behaviour. Specifically, he is seeing what happens to the behaviour and hippocampal physiology of rats when the prelimbic region of the prefrontal cortex is temporarily inactivated. Sumeer is using the place-preference task, a paradigm that separates goal location from site of reward, to see if a rat’s ability to withhold movement within a goal region is impaired when a transient lesion to the prelimbic region (plc) is administered. Preliminary results show that when muscimol, a GABAa agonist, is infused into the plc animals have a markedly decreased ability to remain within a circular goal region for the 2-seconds required to obtain a food reward. However, administration of muscimol does not seem to impair animals’ ability to locate the goal region. Currently, given the few rats that have been tested so far, changes to the electrophysiology of the rat within the dorsal and ventral hippocampus are indeterminate with mixed effects according to varying frequency bandwidth such as 6-12hz theta. Therefore, the results thus far implicate the prefrontal cortex in effective behavioural inhibition towards withholding movement at a goal location.
Emily Crawford
Emily is doing her PhD under the supervision of Dr Harlene Hayne
Past research has shown that drawing helps children to talk about their memories. When drawing is used in experimental conditions to aid memory, children are given explicit instructions to draw about a memory of interest. When drawing is used clinically to aid memory, however, children are sometimes offered the opportunity to draw without being told what to draw about. How exactly does drawing need to be used to aid children’s memory recall of specific events? Do children need draw about the memory of interest, or does any form of drawing aid reporting? To answer these questions, Emily took 76 5- and 6-year-old children on a boat trip. Children were then asked to talk about their memories of the trip. Whilst telling about the trip some children were instructed to draw about the trip, and some children were given drawing materials but were not given any instructions at all about what to draw. Results are currently being analysed.
Rebecca Browning
Rebecca is currently studying towards a PhD with Dr Michael Colombo
Delay activity refers to a change in cell activity during the period between stimulus presentation and a memory test. Because delay activity is typically found when an animal is under memory demand, delay activity is considered to be a neural correlate of memory for a stimulus. However, in animal experiments where there is memory demand, there is also an opportunity to gain a food reward. Therefore, delay activity could in fact code for reward anticipation. Single unit activity was recorded in the nidopallium caudolaterale (NCL) of three pigeons. The pigeons were trained on a directed forgetting version of a delayed matching-to-sample (DMS) task. Red and white coloured discs were used as stimuli. In order to untangle memory demand from reward anticipation, a differential outcome procedure was used so that a correct response on the memory test following a red sample was rewarded with food, but a correct response on the memory test following the white sample was not rewarded. If delay activity is a neural correlate of memory, then significant delay activity should be observed on both red and white trials. On the other hand, if delay activity represents reward anticipation, then we significant delay activity should be observed on red trials, but not on white trials. The findings support the view that delay activity represents a code of the upcoming reward.
Yan Chen
Yan is studying towards a PhD with Dr Harlene Hayne
Parent-child reminiscing is linked to children’s autobiographical memory and self understanding in early childhood. Yan’s study investigates how parent-child reminiscing is related to children’s growing identity and well-being in middle childhood and adolescence. Sixty parents and their children aged between 8 and 12 discussed past emotional events, and the quantity and quality of emotional content was recorded. Children then recalled two life-changing events with a researcher, and as a measure of their identity development. Their level of insight into those events was coded on a 4-point scale. Children’s well-being was measured with Harter’s (1995) Global Self-worth Scale. There were no gender or age-related differences for children’s self-esteem, but girls scored significantly higher level of insight than boys for both age groups. Overall, she found that children’s self-esteem was significantly correlated with the proportion of children’s positive emotions referred to by parents in the middle childhood group, but not in the early adolescent group. Children’s level of insight was significantly correlated with parents’ positive evaluations of children in the middle childhood group, but not in the early adolescent group. The level of insight was significantly correlated with narrative variables only for boys. These results indicate that children experience greater psychological well-being and demonstrate higher levels of identity development if parents referred to them with a greater amount of positive emotion expressions and evaluations during joint reminiscing. Through joint reminiscing, parents can guide children to focus on the experiences that are worth memorising, and consequently children would integrate those memories into part of their identity. This scaffolding process could be more beneficial for boys given that their identity development is at a lower level compared with girls of the same age.
Kirsten Cheyne
Kirsten is currently writing her PhD thesis, under the supervision of
Dr David Bilkey
Hippocampal place cells encode information about the animal’s location in space, essentially providing the animal with a cognitive map. More recent evidence suggests that these cells play a more complex role in spatial navigation, including information about the location of goals within an environment. Kirsten’s research is exploring the possibility that as well as goal location, place cells are also encoding information about the goal value – particularly important when an animal is faced with multiple options. To test this hypothesis rats were trained to run continuously in a figure-of-eight maze with free choice at the decision point. One arm was associated with low reward and low cost; the other with high reward but high cost. The activity of place cells was recorded while rats performed the task, with cost/benefit ratios altered for each of five blocks of 20 trials. Rats quickly adjusted their behaviour in accordance with new cost/benefit ratios, an indication of the perceived value of the goal. Many cells had place fields (areas of significantly increased cell activity) located in the central stem (the region the animal runs through immediately prior to making the spatial decision). The cell firing rate in these fields changed immediately following a change in reward size, and there was a strong correlation between firing rate on the first pass through the stem following a ratio change and the rats’ subsequent arm-choice behaviour within that block. This effect could not be explained by changes in running speed or habituation and was not sustained firing originating at the reward location. Many cells exhibited firing that was highly biased for one turn direction, as has been shown previously in this kind of task. Kirsten showed that cells that were highly biased also tended to be most predictive of future choices. These data support the “goal value” hypothesis and show that place cells dynamically encode the costs and benefits of particular spatial choices on a trial-by-trial basis.
Desiree Dickerson
Desiree is doing her PhD under the supervision of Dr David Bilkey
The temporal coordination of neural firing is believed to underlie the integration of information between and within neural networks in the brain. A deficit in this temporal coordination, or synchrony, is proposed to be a factor underlying many deficits in Schizophrenia including impaired working memory and executive functioning. To explore this hypothesis, Desiree examined the synchrony of activity in electroencephalogram (EEG) and single neuron recordings between and within the medial prefrontal cortex (mPFC) and the hippocampus in the Maternal Immune Activation (MIA) model of schizophrenia. The MIA model is derived from evidence showing an increased risk of schizophrenia in adulthood where prenatal exposure to infection is indicated. The animal model is induced through the acute activation of the immune system of pregnant rat dams by a single injection of a synthetic cytokine inducer, poly I:C. Coherence between hippocampal and mPFC EEG was decreased in magnitude across theta-, beta-, and gamma-band frequencies in the adult MIA offspring as compared to control animals. Further, significant changes in the concentration and phasic relationship of the single unit firing to LPP signal were also was seen in the MIA animals within a number of EEG frequency ranges. These findings mirror the disruption of synchronous neural activity identified in schizophrenia, providing further validation for the MIA model. It also allows a platform for ongoing investigation of the mechanisms underlying synchrony disruption in schizophrenia.
Brad Nicholson
Brad is doing a Masters project with Dr David O’Hare
The aim of Brad’s project is to improve the breadth, and real-world application,
of knowledge about the relationship between cognitive ability and task
workload, regarding the development and transfer of dynamic decision making
(DDM) performance; for the purpose of increasing the effectiveness of
training programmes designed to improve DDM performance. The primary assessment
tool used in Brad’s research is the computer task called WOMBAT™ version
4.0; which is thought to measure situational awareness. The WOMBAT programme
includes tasks that require examinees to hold and manipulate information
in memory whilst checking the performance of a joystick operated geometric
tracking task. Part of Brad’s data analysis will involve investigating
the relationship between performance on the WOMBAT working memory task
and the transfer of dynamic decision making performance; in the context
of the decision making a fire chief might be expected to engage in.
Tia Neha
Tia is in the second year of her PhD under the supervision of Dr Elaine
Reese and Dr Tamar Murachver..
Tia is investigating the role of family narratives and its association with Māori children’s learning. Previous psychological research has shown that non Māori mothers’ story telling styles with their children are linked to children’s language and reading ability. Tia therefore aims to replicate and extend the existing literature by identifying whether or not Māori mother-child dialogues have an influence on their children’s reading and further, their mathematical ability. Additionally, she has measured the children’s behavioural regulation and learning which involves components of executive function including attention, working memory, and self or inhibitory control. To date there have been no studies that have explored Māori children’s learning through family narratives and self-control. Thus, it is anticipated that this research will be beneficial to whānau, policy makers, researchers, psychologists and educators.
DEPARTMENT OF ANATOMY AND STRUCTURAL BIOLOGY
Ana Claasen
Ana is studying towards a PhD with Dr Joanna Williams (Anatomy) and Dr
Warren Tate (Biochemistry)
Ana is part way through her PhD, studying mechanisms of memory with a focus on a protein called sAPPa. This neuroprotective and neurotrophic protein is decreased in the brains' of Alzheimer patients, and loss-of-function may play a role in disease aetiology. Little is known about the physiological role of sAPPa in the brain, though evidence from the Abraham and Williams labs suggest it plays a crucial role in learning and memory, especially synaptic plasticity. Ana's project aims to elucidate how sAPPa regulates synaptic protein synthesis, an important effector of synaptic plasticity, and to identify putative receptors for the protein. This research will further our understanding of sAPPa biology, and potentially aid in identifying novel therapeutic targets for Alzheimer's disease.
James McKearney
James is in the completion stages of writing up his Masters project that
he did with Dr Joanna Williams
James has been investigating AMPA receptor trafficking, an important aspect of synaptic plasticity. Specifically he has been looking at the effect Group I metabotropic glutamate receptor activation has on AMPA receptor trafficking. Group I metabotropic receptors have been shown to prime for future Long Term Potentiation and also induce Long Term Depression, therefore they appear to have an important role in molecular memory mechanisms. Using western blot analysis and protocols that can separate surface proteins from intracellular proteins, and synaptic proteins from non-synaptic proteins he has produced results suggesting that there is trafficking of calcium permeable AMPA receptors from intracellular pools to extrasynaptic sites. This could be a mechanism by which metabotropic glutamate receptors prime the synapse for long term potentiation.
Otago University Memory Theme Student Mini-Symposium 2005 Report
Postgraduate research presentations were held Friday 9th September from 3-5 pm. Following presentations the attendees had dinner at The Palms restaurant. Once again, all students who presented their research and went to dinner had a very enjoyable time. It was a fantastic opportunity for us all to meet together; for the “old hands” in the department to share how our work is progressing, to meet up with new students in the department and hear about their research, and then to have a fun night out. A brief summary of research is presented below, which highlights the varied and interesting nature of memory research conducted at the University of Otago.
Professor Hayne's Laboratory: Development of Learning and Memory in Infants and Young Children
Fiona Wright: Mother-Child Conversations and the Development of Autobiographical Memory
Research suggests that talk about past events in the context of mother-child conversations contributes to the development of autobiographical memory. In mother-child conversations, two speech styles have been identified: high elaborative and low elaborative; most mothers tend to use one style more than the other. Research has shown that children with high elaborative mothers report more information about past events than do children with low elaborative mothers. Approximately seven years ago, research was conducted in the Hayne laboratory which recorded past-event conversations between mother-child dyads when the children were aged 24-40 months. Fiona has now interviewed these children at age 12-13 years about their memories for things that happened at different ages in childhood and asked them to tell their earliest memory. If mothers' narrative style during parent-child conversations influences the development of autobiographical memory, there should be a relation between the narrative style used by mothers when the children were young and the age of children's earliest memories and/or the amount that these adolescents report about their childhood memories.
Nicola Davis: Memory for Sibling Birth: Implications for Childhood Amnesia
Childhood amnesia is defined as adults' inability to recall events from their infancy and early childhood. While there is general consensus regarding the existence of childhood amnesia, there remains debate over its boundary. One way that researchers have examined the boundary of childhood amnesia is to ask adults specific questions regarding their sibling's birth (an event that can be accurately dated). On the basis of answers to specific questions, researchers argue that the boundary of childhood amnesia occurs between the ages of 2-4 years. On the one hand, specific questions may under-estimate the boundary because participants can often guess the answers to many of the questions. On the other hand, specific questions may also over-estimate the boundary because the questions typically focus on developmentally inappropriate details. Nicola's experiment compared adults' answers to the specific questions used in prior research and to a free-recall question. All participants had a younger sibling who was born when they were 1-5 years of age. The results will reveal whether questioning style has an influence on the boundary and will also have important implications for the debate over the boundary of childhood amnesia.
Katrina Sugrue: Investigating the Creation of False Memories Using the DRM Paradigm
Katrina's PhD investigates factors that influence the creation of false memories using the Deese-Roediger-McDermott (DRM) paradigm. In the DRM paradigm, adults who studied a list of words (e.g., sour, candy, sugar, bitter, good) often falsely reported a related word, known as the critical target (i.e., sweet), even though the target word did not appear on the original list. In one of Katrina's experiments, she found that adults made more memory errors than 10-year-olds when tested with long (but not short) lists; however, in subsequent experiments, which used similar procedures, there was no age-related difference in false memory rates. The difference in socio-economic status between the various samples may account for the discrepant findings. Katrina's research suggests that 10 years of age may represent a transition point where children from high SES backgrounds perform similarly to adults.
Ghazi Metoui: Do Human Figure Drawings Facilitate Children's Reports of Past Experiences of Touch?
Children have increasingly been called upon to serve as witnesses in the investigations and prosecution of allegations of child sexual abuse, and it has become clear that we need to know more about how to maximise the amount of correct information and minimise the amount of incorrect information in children's memory reports. One procedure that has been advocated as an aid to interviewing children is the anatomically-detailed doll. The basic rationale for using dolls is that they may elicit information from children who are unwilling or unable to provide a verbal report. Many researchers have concluded that children, and especially young children, are inaccurate at reporting and showing on the doll whether, and where, they had been touched. Due to the problematic nature of using dolls, human figure drawings have been promoted as a potential alternative interview aid. Ghazi's study assessed children's ability to report touch under two conditions: human figure drawing and verbal. Results showed that children in both conditions were poor at reporting where they had been touched. Children were no better off at accurately reporting where they had been touched regardless of whether providing a report with the aid of a human figure drawing or simply providing a verbal report. Furthermore, children in both conditions were equally suggestive and as likely to falsely report touch. Ghazi concluded that children's ability to accurately provide reports of touch is not facilitated by human figure drawings.
Dr Rachel Zajac's Laboratory: Children's Eyewitness Testimony
Sarah O'Neill: Individual Differences in 9- and 10-year-old Children's Response to Cross-Examination: The role of Cognitive Factors
Sarah's PhD research has involved examining which children are the most at risk from the negative effects of cross-examination on the accuracy of their testimony. To achieve this, her first study investigated the role of individual difference factors (i.e., language ability, memory, and IQ) on 5- to 6-year-old children's performance under cross-examination-style questioning. The results of this study have indicated that, within the normal range of intellectual ability, cognitive factors play a small but significant role in children's cross-examination performance. Are these findings stable across children's development? Sarah's second study investigates individual differences in 9- and 10-year-old children's responses to cross-examination-style questioning. Children undergo significant cognitive development between early and middle childhood, therefore, qualitative and quantitative changes in the relative influence of cognitive factors on children's response to cross-examination-style questioning is of primary interest. Addressing this issue is vital when considering development of pre-trial interventions designed to improve children's performance during cross-examination. Children (9 and 10 years) will be recruited from decile 1, 5, and 10 schools. They will partake in a unique event, and then will be questioned in two styles: direct examination and cross-examination. Individual difference measures will then be administered to assess memory, IQ, and receptive and expressive language ability. The ability of these cognitive factors to predict cross-examination performance will then be analysed.
Dr Louis Leland's Laboratory: Behaviour Analysis Applied to Community Change
Michelle Grainger: Factors Influencing Preventative Medication Adherence in Asthmatics
Asthmatics are known to be especially poor at taking their asthma medications as prescribed; both under-using their preventative medication, and over-using their reliever medication. Michelle's research focuses on determining asthmatics' reasons for adherence and non-adherence to preventative medication, with the aim of increasing adherence levels in this group. Results of two separate studies of undergraduates with asthma show that forgetting to take preventative medication is the most commonly reported reason for non-adherence. This suggests a prospective memory problem (i.e. remembering the intention to take the medication). In order to improve adherence levels, interventions that decrease forgetting rates (e.g. attaching preventative inhalers to toothbrushes so medication will be cued to the automatic process of brushing teeth) will hopefully increase asthmatics' prospective memory for taking their preventative medication regularly.
Professor Bob Knight's Laboratory: Assessing Memory and Measuring Emotional Reactions
Maria Crawford: Speed of Retrieval after Traumatic Brain Injury
Although it is well established that persons with traumatic brain injury (TBI) experience word retrieval difficulties, the underlying cause of these deficits is not known. The primary aim of Maria's thesis was to determine whether the speed of word retrieval was slowed in persons with TBI. Another aim was to investigate the underlying cause of problems with word retrieval after TBI. In three separate studies patients with TBI and matched controls were given a series of word fluency tasks and the speed of word generation was measured. A procedure developed by Rohrer, Wixted, Salmon, and Butters (1995) was used to determine whether slowed retrieval or degraded semantic stores were responsible for patients' word retrieval difficulties. Overall, results showed that an underlying slowness of word processing is the primary cause of all word retrieval problems in persons with TBI.
Dr Liz Franz's Laboratory: Neural Mechanisms of Complex Action
Vickie Saunders: Language Deficits in Parkinson's Disease
Parkinson's disease is a neurodegenerative disorder, which is typically characterised in terms of its debilitating effects on motor function. Measurable neuropsychological deficits, however, are also an integral feature of the progression of this disease. Vickie investigated these cognitive deficits as they manifest in language. In the first series of studies, the integrity of the semantic network and access to semantic memory were assessed using a novel semantic categorisation task. A Parkinson's group was found to be impaired relative to an age-matched control group in the consistency with which they categorised common kitchen items. This inconsistency was particularly apparent at category boundaries, suggesting a possible impairment in semantic memory. Alternatively, the Parkinson's group may have adopted a less optimal categorisation rule than the control group, which lead to an inability to deal with atypical category members. The structure of the semantic system was further investigated using a verbal memory task, which required participants to recall word lists. These word lists consisted of semantically associated words and were designed to elicit false recall of another close semantic associate. The overall correct recall of the word lists did not differ between the groups. Vickie also found, somewhat surprisingly, that the Parkinson's group recalled more of the false critical lures than the control group. This result suggests normal saliency of semantic categories and an intact semantic network, otherwise automatic spreading activation mechanisms in semantic memory would have been nullified, and the Parkinson's group would have recalled fewer critical lures than the control group.
Dr Richard Linscott's Laboratory: Neurocognition in Schizophrenia
Daria Korobanova: Preliminary Evidence of Impaired Recollection in Schizotypy
Evidence on the relationship between automatic memory (AM) and schizophrenia is ambiguous. Studies that have solicited oral responses to memory cues demonstrate potentiated AM in schizophrenia and schizotypy, whereas AM levels appear normal in schizophrenia if tasks solicit written responses. In contrast, effortful or controlled memory (CM) is unambiguously impaired. Daria's aim was to determine whether schizotypy is associated with potentiated AM and impaired CM when these are assessed using a group-administered cued-recall task in which participants were required to provide written responses to cues. Two risk groups were contrasted: one using positive indicators of schizotypy and another with measures of physical and social anhedonia. 1776 introductory psychology students completed a self-report measure of attributes of schizotypy and anhedonia. A subset of these participants (n = 233) also completed a word-stem completion task. Non-overlapping schizotypy (n = 25), anhedonia (n = 21), and control groups (n = 22) were identified. Results showed that groups were equally competent in terms of base-rate word-stem completion. CM was impaired in the schizotypy group (effect size d = 0.78) but not in the anhedonia group (d = 0.18). In contrast, AM levels did not differ across the three groups. Daria concluded that CM is impaired in schizotypal individuals but intact in anhedonic individuals. AM appears intact in schizotypy and anhedonia if cued recall is assessed by soliciting written responses to cues. Potentiated AM in schizophrenia and schizotypy may be mediated by aberrations in processes that are more likely to be employed when oral responding is required.
Professor Cliff Abraham's Laboratory: Cellular and Molecular Mechanisms of Synaptic Plasticity
Chanel Taylor: The Role of Secreted Amyloid Alpha in Alzheimer's Disease
Secreted amyloid-alpha is different to the well known Alzheimer's protein, "amyloid-beta", as it is neurotrophic and can promote memory formation when injected into rats (as opposed to amyloid-beta, which is believed to cause Alzheimer's disease). Chantal investigated whether secreted amyloid-alpha contributes to the formation of memory using the molecular model of memory formation, long-term potentiation. She found that secreted amyloid-alpha is necessary and sufficient for memory formation.
Jeremy Kennard: Which Proteins are Required to Maintain LTP?
Long-term potentiation of synaptic transmission, or LTP, in the hippocampus, is a molecular model of learning and memory. Jeremy's research investigates the mechanisms involved in the long-term maintenance of LTP, specifically seeking to determine the proteins required to maintain LTP, which is known to require de novo protein synthesis.
Professor Neil McNaughton's Laboratory: Neurobiology of Anti-Anxiety Drugs and Temporal Lobe Function
Ming Ruan: Brain Bypass: The Role of Rhythmic Waves in Mental Processing
Ming's research aimed to identify the extent to which rhythmic theta waves affect learning and memory. Ming blocked rhythmic input to the hippocampus and therefore blocked learning. He then bypassed the blocked area with an external electrical circuit which reinstated both hippocampal rhythmicity and learning, despite the fact that precise firing patterns of neurones were not reinstated. From Ming's research it was concluded that brain rhythmicity is important for mental processing and a key factor for theories of brain function. The finding also suggests that simple alterations of rhythmicity could be used to alter learning and memory.
Calvin Young: Low Doses of Ethanol on Theta Rhythm and Working Memory
Givens (1995) has found that low doses of ethanol increase theta activity measures and enhance working memory performance. Other research, however, show equivocal effects of low dose ethanol on theta rhythm. Calvin's research explores the behavioural state of the animal as a significant factor on the effect of low dose ethanol on theta frequency.
Associate Professor David Bilkey's Laboratory: Biological Basis of Memory
Kirsten Cheyne: Hippocampal Place Cells
Hippocampal place cells have been found that encode not only the location of an animal, but also places the animal has recently visited, as well as future locations. Kirsten trained rats to alternate in a figure-8-shaped maze (to almost 100% accuracy). She is currently recording from cells that fire differentially for future left- and right-turn trials, so that one can predict the direction the rat will turn. Kirsten plans to impose a long delay to decrease the animals' accuracy to less than 70%, so she can investigate the activity of the cells in trials where the animal makes an error; that is, what happens to the representation of upcoming decisions when the strength of the memory trace is degraded?
If you are interested in further information about the Student Memory Theme, please contact Professor Mike Colombo.
