Projects : Mind and Brain : University of Sussex

The following list highlights some of the externally funded Mind and Brain projects currently being undertaken by Sussex Faculty.

A Unified Model of Compositional and Distributional Semantics: Theory and Applications

Dr David J Weir, Engineering and Physical Sciences Research Council

There have been two main approaches to modelling the meaning of language in NLP. The first, the so-called compositional approach, is based on classical ideas from Philosophy and Mathematical Logic. Using a well-known principle from the 19th century logician Frege - that the meaning of a phrase can be determined from the meanings of its parts and how those parts are combined - logicians have developed formal accounts of how the meaning of a sentence can be determined from the relations of words in a sentence. This idea culminated famously in Linguistics in the work of Richard Montague in the 1970s. The compositional approach addresses a fundamental problem in Linguistics - how it is that humans are able to generate an unlimited number of sentences using a limited vocabulary. We would like computers to have a similar capacity also. The second, more recent, approach to modelling meaning in NLP focuses on the meanings of the words themselves. This is the so-called distributional approach to modelling word meanings and is based on the ideas of the "structural" linguists such as Firth from the 1950s. This idea is also sometimes related to Wittenstein's philosophy of "meaning as use". The idea is that the meanings of words can be determined by considering the contexts in which words appear in text. For example, if we take a large amount of text and see which words appear close to the word "dog", and do a similar thing for the word "cat", we will see that the contexts of dog and cat tend to share many words in common (such as walk, run, furry, pet, and so on). Whereas if we see which words appear in the context of the word "television", for example, we will find less overlap with the contexts for "dog". Mathematically we represent the contexts in a vector space, so that word meanings occupy positions in a geometrical space. We would expect to find that "dog" and "cat" are much closer in the space than "dog" and "television", indicating that "dog" and "cat" are closer in meaning than "dog" and "television". The two approaches to meaning can be roughly characterized as follows: the compositional approach is concerned with how meanings combine, but has little to say about the individual meanings of words; the distributional approach is concerned with word meanings, but has little to say about how those meanings combine. This project exploits the strengths of the two approaches, by developing a unified model of distributional and compositional semantics. The project has a central theoretical component, drawing on models of semantics from Theoretical Computer Science and Mathematical Logic. This central component which will inform, be driven by, and evaluated on tasks and applications in NLP and Information Retrieval, and also data drawn from empirical studies in Cognitive Science (the computational study of the mind). Hence we aim to make the following contributions: (i) advance the theoretical study of meaning in Linguistics, Computer Science and Artificial Intelligence; (ii) develop new meaning-sensitive approaches to NLP applications which can be robustly applied to naturally occurring text.

This multisite project is funded by the EPSRC, with related grants funding the project at the Universities of Cambridge, Edinburgh, Oxford and York.

Green Brain: Computational Modelling of the Honeybee Brain

Dr Thomas Nowotny, Dr James Marshall, Dr Eleni Vasilaki, Professor Kevin Gurney, Engineering and Physical Sciences Research Council

The development of an ‘artificial brain’ is one of the greatest challenges in artificial intelligence, and its success will have innumerable benefits in many and diverse fields, from robotics to cognitive psychology. Most research effort is spent on modelling vertebrate brains. Yet smaller brains can display comparable cognitive sophistication, while being more experimentally accessible and amenable to modelling. The ‘Green Brain’ project will combine computational neuroscience modelling, learning and decision theory, modern parallel computing methods and robotics with data from state-of-the-art neurobiological experiments on cognition in the honeybee Apis mellifera, to build and deploy a modular model of the honeybee brain describing detection, classification and learning in the olfactory and optic pathways as well as multi-sensory integration across these sensory modalities. Unlike other brain models which use expensive traditional supercomputing resources, the ‘Green Brain’ will be implemented on massively parallel, but affordable GPU technology. The ‘Green Brain’ will be deployed for the real-time control of a flying robot able to sense and act autonomously; this robot testbed will be used to demonstrate the development of new biomimetic control algorithms for artificial intelligence and robotics applications. Further, by modelling complete sensorimotor loops endowed with behaviour, we will be able to begin examining the nature of embodied cognition in biological brains rather than abstract agents.

The role of vicarious learning in preventing and treating children's fears

Joint project with Kingston University, Dr Chris Askew (PI) Professor Andy P Field, Economic and Social Research Council

Anxiety is the most common of all childhood psychological disorders. It frequently hinders children's social and academic functioning and can therefore lead to problems in later life. Children can learn to become frightened of certain objects if they witness someone else acting frightened of them. This process is called "vicarious learning". To develop the most effective prevention and treatment programmes for fears acquired in this way it is necessary to understand when and how vicarious learning occurs by investigating the mechanism underpinning it. This is the first aim of the research programme. As with other anxiety disorders, clinical fears and phobias are associated with specific patterns of responses toward the feared object, including: avoiding it, saying negative things about it, and increased heart rate. Researchers have found that vicarious learning can cause changes in the first two types of response, but to better understand phobias it's important to show changes in heart rate too. Researchers have also shown that anxiety is typically maintained by biased ways of looking and thinking; in particular, anxious individuals tend to notice and pay more attention to their feared object (attentional bias). However, although it is thought likely that these biases begin in childhood, it is not yet known how or why they develop. Hence, we still know relatively little about this very important component of anxiety, therefore limiting our ability to prevent anxiety from developing in children. One probable scenario is that these biases begin following learning experiences with the feared object. The second aim of the research is therefore to see whether vicarious learning can affect heart rate responses to an object and how much attention is paid to it. A third aim is to evaluate ways of preventing and treating the negative outcomes of vicarious learning. Recent studies show that anxiety is reduced when people are trained to divert their attention away from the object of their fear (attentional training). We will examine whether vicariously learnt fear responses towards animals can be reversed using this type of training. Finally, we will investigate whether vicarious learning can also be used to protect against acquiring fears and eliminate existing fears. This work is of interest to psychologists, parents and teachers. It will offer guidance on how to minimise the risk of transmitting fears to children and suggest ways to intervene quickly when it is recognised that a child may have been involved in a fear-related vicarious learning event. Finally, the research also has wider implications for how animals and other stimuli are presented to children (e.g. on television, in films, or in books).

Diagnosing vulnerability and ‘dangerousness’: police decision-making in the implementation of Section 136

Professor Gillian A Bendelow, BA Senior Research Fellowship in collaboration with Sussex Partnership NHS Foundation Trust and Sussex Police. British Academy

Public anti-social behaviour is increasingly a major societal concern and police in England and Wales are empowered, under Section 136 of the Mental Health Act 1983, to detain individuals who are thought to be a danger to themselves or to others. Use of this authority is widespread, but attracts controversy, as it requires the police to make judgements about mental health. Detention under section 136 in Brighton and Hove is approximately ten times the national average, but over the last year, less than one third of police detainees in public places were diagnosed as having a 'treatable' mental illness. This research ties together previous theoretical and emprical work by tracking and recording the decision- making processes of both police and mental health professionals involved in ALL s136 case over one year in Sussex, using in-depth interviews and observational techniques. Findings would produce policy implications to address seemingly intractable problems at both local and national levels, as well as contributing to current diagnostic debates around dangerous and vulnerable 'personality disorders'.

CATEGORIES: The origin and impact of colour categories in language and thought

Dr Anna Franklin, European Union

Humans can discriminate millions of colours, yet language refers to colour using a number of discrete categories (e.g., red, green, blue). These colour categories are also present in thought (e.g., in colour judgements / memory). There has been considerable multidisciplinary research into the origin of colour categories and how colour categories in thought and language relate. However, major theoretical challenges remain. The 5 year 'CATEGORIES' project, led by Franklin, will tackle these crucial challenges. In our previous research, we have established that infants respond categorically to colour. The first aim of the ‘CATEGORIES’ project is to establish the relationship of these pre-linguistic colour categories to the commonality and variation in the world’s colour lexicons. In order to achieve this, we are conducting a series of sub-projects which draw on a diverse range of methods (e.g., infant testing, computational simulations, psychophysics, cross-cultural fieldwork). The second aim is to resolve the debate about the effect of colour terms on colour perception. It has previously been claimed that speakers of different colour lexicons see colour differently, a proposal which relates to Whorf’s hypothesis (1956) that language influences our perception of the world. We are developing a ‘Neuro-Whorfian’ approach, using neuro-physiological methods to make cross-linguistic comparisons of colour processing. Overall, the project aims to provide new questions, approaches, data and theory to the multidisciplinary field of colour category research. More broadly, the project addresses issues that are fundamental to understanding the complexity of the human mind, such as the interaction of language and thought, and how the brain categorises the visual world.

EXPECT_CONSCIOUS: When do expectations affect conscious perception?

Professor Anil K Seth and Dr. Yair Pinto, European Union

There is accelerating interest in the role of expectations (predictions) in cognition and behaviour, under the general rubric of ‘predictive coding’. Abundant evidence now demonstrates influences of expectations, at both behavioural and neural levels, in sensorimotor performance and perception. A version of predictive coding has even been suggested as a fundamental principle underlying all aspects of brain operation. However, the influence of expectations specifically on conscious perception remain largely unknown. The present project, a Marie Curie fellowship awarded to Prof Seth and Dr. Yair Pinto, who joins from the University of Amsterdam, addresses this issue head on. The team will ask under what conditions can stimuli induce expectations that influence subsequent conscious perception. Specifically, they will use a combination of psychophysics and neuroimaging to examine (i) the role of ‘top-down’ versus ‘bottom-up’ expectations, and (ii) whether attention and/or subjective visibility is necessary such that expectation-inducing stimuli affect subsequent perceptions. Behavioural experiments will expose the functional architecture of interactions between expectations and conscious perception, and neuroimaging studies will reveal aspects of the underlying neural mechanisms. Combining these approaches will allow us to situate the work within – and help develop – mechanistic contexts provided by predictive coding within cortical hierarchies.

EXPECT_CONSCIOUS fits within in a larger research programme, pursued within the Sackler Centre for Consciousness Science, aimed at understanding the roles of prediction and expectation in conscious experience. Visit the Sackler Centre website for more information.

The dynamics of interneuronal communication in the brain

The Mind and Brain Theme is helping to unravel consciousness from the cell to self and personal identity.

By demonstrating novel dynamic processes in individual neurons, a research team at the University of Sussex are helping to understand how cells might adjust their communication properties to support the flexible output of the nervous system and even learning and memory formation.

Repair of topoisomerase-mediated and oxidative-stress induced DNA damage

Dr Sherif F. El-Khamisy is the Principal Investigator for a three year Wellcome Trust funded research grant on the repair of topoisomerase-mediated and oxidative-stress induced DNA damage: novel factors and implications on neuronal function.

Breaking and sealing one strand of DNA is a common feature of chromosome metabolism to overcome torsional barriers. Failure to reseal broken DNA strands results in protein-linked DNA breaks causing neurodegeneration in human. This is highlighted by a mutation of the 3’-DNA processing enzyme tyrosyl DNA phosphodiesterase (TDP1) which removes topoisomerase 1 peptide from DNA termini. Mutation of this enzyme results in spinocerebellar ataxia and degeneration of post-mitotic neuron in the cerebellum. Research in my lab is focussed on understanding how mammalian cells repair this type of DNA damage and the implications of failure of these mechanisms with respect to neuronal function and viability. These breaks can also arise from other abortive enzymatic activities and from attacks by reactive oxygen species during normal metabolic transactions. We use a combination of yeast genetics, molecular, cellular, and whole animal approaches to examine these mechanisms and determine the extent of their regulation and subsequent impact on neuronal viability and human health. Recently we identified a novel protein named TDP2, which is similar to TDP1 and we are currently investigating its role in neuroprotection.

For further details please visit the El-Khamisy Lab website

GABA alpha Receptors in accumbens neural circuits underlying drug abuse

Professor Dai Stephens is the Principal Investigator for a three year MRC funded research grant on GABA alpha Receptors in accumbens neural circuits underlying drug abuse: a target for treatm.Our research investigates the role of the GABAergic systems in brain areas known to be involved in the action of addictive drugs, and in controlling addictive behaviour. As part of our research we have discovered in human cocaine addicts that variations (haplotypes) of the gene encoding the alpha2 subunit of GABA_A receptors contribute to the risk of developing addiction. We think that this comes about because these receptors play an important role in signaling information in a part of the brain called the nucleus accumbens that is known to play an important role in evaluating both rewarding events and occurrences that provide information that rewarding events are nearby. We have found that reducing expression of the same gene in mice leads to a disruption in their ability to organize their behaviour appropriately in response to such predictors of reward. One arm of our research is now studying whether the variations in the gene that increase risk for cocaine addiction in people also increase the influence of reward predictors in driving behaviour, which might explain why they predispose to drug abuse. We would then seek either behavioural or pharmacological treatments that will help protect potentially vulnerable individuals from developing addictions or treat those who have already become addicted.

For further details please visit the project website.

Molecular Characterisation of a Novel Human Tyrosyl DNA Phosphodiesterase

Professor Keith Caldecott is the Principal Investigator for a three year MRC funded research grant on Molecular Characterisation of a Novel Human Tyrosyl DNA Phosphodiesterase.

Prof Caldecott's laboratory is focused on understanding the link between defects in DNA strand break repair and hereditary disease, including cancer and neurodegeneration, and possible links between this process and pathologies associated with human ageing. Part of this work aims to identify new human genes that are involved in the response to DNA strand breaks. Recent projects have identified two new such genes including one the team has now officially named, via the HUGO human gene nomenclature committee, as tyrosyl DNA phosphodiesterase-2 (Tdp2). This gene encodes a novel protein activity that repairs broken chromosomes during a molecular process known as DNA double-strand break repair. Tdp2 is the primary, and possibly only, enzyme of its type in human cells, and in addition to characterising the importance of this enzyme in genome protection and maintenance, focus now rests on exploring ways to exploit these findings for clinical benefit, during anti-cancer therapy.

For further details please visit the Caldecott Lab website.

How do ants use, encode & identify natural panoramic scenes?

Dr Paul Graham is the Principal Investigator for a three year BBSRC grant researching how ants use, encode and identify natural panoramic scenes.

Being able to navigate between important locations is a fundamental requirement for almost all animals. Fortunately the world provides ample information for navigation in the form of stable objects which most animals perceive visually. Interestingly, when we look at animal navigation, we see the similar visual navigation strategies in animals from ants to humans; And ants provide an excellent system to study navigation as ant colonies have specialist foragers whose only purpose is to navigate between their nest and productive foraging grounds. The aim of our current project is to examine in the lab and field the ways in which ants use, encode and recognise natural visual scenes. Despite its importance for navigation, little is known about how any animal encodes and identifies a natural scene. Insects with their low resolution eyes and small brains are likely to have efficient ways of encoding scenes. The interest in the elegant solutions that ants have evolved for visual navigation comes from diverse fields. Ants are inspiring to biomimetic engineers and for psychologists they represent the minimal mechanistic and cognitive requirements for complex spatial behaviour.

For further details please visit the project website.

ITN LCG: Initial Training Network - Language, Cognition and Gender

Dr Alan Granham is the Principle Investigator for a four year European Union funded research grant on ITN LCG: Initial Training Network - Language, Cognition and Gender which is part of a Marie Curie Initial Training Network (ITN).

The Marie Curie Initial Training Network - Language, Cognition, and Gender (ITN LCG) investigates European languages from an interdisciplinary perspective to expand current knowledge of how language influences and forms the cognitive representations of women and men. To enhance the scientific understanding of this topic, ITN LCG provides a research programme and a structured training programme for 15 early stage researchers (ESR) and 3 experienced researchers (ER). The interplay of Language, Cognition, and Gender is investigated from cross-language and cross-cultural perspectives by partners from 10 universities of the Czech Republic, Germany, Italy, Norway, Spain, Switzerland, and the United Kingdom and associated partners from public and private sectors.

There are two individual projects at Sussex, supervised by Dr Alan Granham and Prof Jane Oakhill, who is also the leader of Work Package A, which is one of four groups of projects in the network.

The two projects are:

1. Are stereotype violations processed as syntactic or semantic/pragmatic anomalies?
An electrophysiological analysis by Postdoctoral Marie Curie Research Fellow Dr Paolo Canal.

2. Strategies for overcoming gender stereotypes in cognitive representations.
An ESR (Early Stage Researcher) project by Marie Curie Research Fellow Eimear Finnegan.

Further details on the projects and the Marie Curie Intial Training Network (ITN) are available here.

Effects of stress on appetitive Pavlovian to Instrumental Transfer (PIT)

Dr Theodora Duka is the Principal Investigator for a four year Janssen Pharmaceutica NV funded research grant on 'Effects of stress on appetitive Pavlovian to Instrumental Transfer (PIT)'.

The effects of negative mood on expression of appetitive conditioning under conditions of reduced reward value or of negative consequences.¹

Learned predictive Pavlovian stimulus-outcome contingencies for a reward are able to be transferred, by humans, to instrumental responding for that same outcome in Pavolvian to Instrumental transfer (PIT).

Pavlovian to Instrumental transfer (PIT) is a model used to demonstrate how stimuli associated with an addiction, for instance alcohol drinking or smoking, activate in their presence the behaviour to drink or smoke further. However, little is known about the mechanisms involved in the transfer and the conditions under which it may be modified in humans.

In the current project we aim to examine in a series of studies the effect of 1) changes in mood states and 2) changes in the value of the reward outcome on the strength of this transfer. The results will provide an insight into how conditioned stimuli control behaviour in several forms of addiction and will inform behavioural or pharmaceutical treatment approaches.

Negative mood is often associated with anhedonia, characterised by decreased sensitivity to pleasurable events, and since it is generally accepted that PIT is mediated by the prediction of the outcome, such that the magnitude of the transfer effect accords with the associative (or predictive) strength of the stimulus, we were particularly interested in the extent to which induced negative mood might reduce instrumental responding in a PIT paradigm and whether this reduction would accord with the predictive strength of the stimulus. We predicted that negative mood would reduce the value of the outcome by inducing anhedonia, which would reduce instrumental responding.

The findings suggested that the motivation to perform an acquired instrumental response to obtain reward (money gain), in the presence of stimuli which predicted via Pavlovian contingencies money gain (reward) was reduced under conditions of negative mood. At the same time the cognitive evaluation of the reward strength predicted by the stimuli (measured by the expectancy of the outcome) and the intensity of the reward value the stimuli predicted (measured by an emotional response) remained unaffected. Thus attentional, cognitive or emotional processes remained unaffected by the induction of negative mood whilst motivation to respond was reduced. Similar results were obtained when the outcome predicted by the stimulus was aversive (white noise) and an acquired avoidance response to block a white noise was measured. Thus negative mood (modelling a depressive state) decreases both the action to obtain a reward and the action to avoid a punishment without affecting the reward value. Further studies modifying directly the value of the reward and introducing reward-punishment conflict are in progress.

¹This is a BBSRC CASE studentship (Student: Claire Mathers, Supervisor: Theodora Duka