What Makes a Pattern? Matching Decoding Methods to Data in Multivariate Pattern Analysis

Research in neuroscience faces the challenge of integrating information across different spatial scales of brain function. A promising technique for harnessing information at a range of spatial scales is multivariate pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data. While the prevalence of MVPA has increased dramatically in recent years, its typical implementations for classification of mental states utilize only a subset of the information encoded in local fMRI signals. We review published studies employing multivariate pattern classification since the technique’s introduction, which reveal an extensive focus on the improved detection power that linear classifiers provide over traditional analysis techniques. We demonstrate using simulations and a searchlight approach, however, that non-linear classifiers are capable of extracting distinct information about interactions within a local region. We conclude that for spatially localized analyses, such as searchlight and region of interest, multiple classification approaches should be compared in order to match fMRI analyses to the properties of local circuits

Neural processes underpinning episodic memory

Episodic memory is the memory for our personal past experiences. Although numerous functional magnetic resonance imaging (fMRI) studies investigating its neural basis have revealed a consistent and distributed network of associated brain regions, surprisingly little is known about the contributions individual brain areas make to the recollective experience. In this thesis I address this fundamental issue by employing a range of different experimental techniques including neuropsychological testing, virtual reality environments, whole brain and high spatial resolution fMRI, and multivariate pattern analysis. Episodic memory recall is widely agreed to be a reconstructive process, one that is known to be critically reliant on the hippocampus. I therefore hypothesised that the same neural machinery responsible for reconstruction might also support ‘constructive’ cognitive functions such as imagination. To test this proposal, patients with focal damage to the hippocampus bilaterally were asked to imagine new experiences and were found to be impaired relative to matched control participants. Moreover, driving this deficit was a lack of spatial coherence in their imagined experiences, pointing to a role for the hippocampus in binding together the disparate elements of a scene. A subsequent fMRI study involving healthy participants compared the recall of real memories with the construction of imaginary memories. This revealed a fronto-temporo-parietal network in common to both tasks that included the hippocampus, ventromedial prefrontal, retrosplenial and parietal cortices. Based on these results I advanced the notion that this network might support the process of ‘scene construction’, defined as the generation and maintenance of a complex and coherent spatial context. Furthermore, I argued that this scene construction network might underpin other important cognitive functions besides episodic memory and imagination, such as navigation and thinking about the future. It is has been proposed that spatial context may act as the scaffold around which episodic memories are built. Given the hippocampus appears to play a critical role in imagination by supporting the creation of a rich coherent spatial scene, I sought to explore the nature of this hippocampal spatial code in a novel way. By combining high spatial resolution fMRI with multivariate pattern analysis techniques it proved possible to accurately determine where a subject was located in a virtual reality environment based solely on the pattern of activity across hippocampal voxels. For this to have been possible, the hippocampal population code must be large and non-uniform. I then extended these techniques to the domain of episodic memory by showing that individual memories could be accurately decoded from the pattern of activity across hippocampal voxels, thus identifying individual memory traces. I consider these findings together with other recent advances in the episodic memory field, and present a new perspective on the role of the hippocampus in episodic recollection. I discuss how this new (and preliminary) framework compares with current prevailing theories of hippocampal function, and suggest how it might account for some previously contradictory data

Short-term memory and long-term memory are still different.

A commonly expressed view is that short-term memory (STM) is nothing more than activated long-term memory. If true, this would overturn a central tenet of cognitive psychology-the idea that there are functionally and neurobiologically distinct short- and long-term stores. Here I present an updated case for a separation between short- and long-term stores, focusing on the computational demands placed on any STM system. STM must support memory for previously unencountered information, the storage of multiple tokens of the same type, and variable binding. None of these can be achieved simply by activating long-term memory. For example, even a simple sequence of digits such as "1, 3, 1" where there are 2 tokens of the digit "1" cannot be stored in the correct order simply by activating the representations of the digits "1" and "3" in LTM. I also review recent neuroimaging data that has been presented as evidence that STM is activated LTM and show that these data are exactly what one would expect to see based on a conventional 2-store view. (PsycINFO Database Recor

A multimodal investigation of moral decision making in harmful contexts

Since the two landmark publications in moral psychology (Greene, Sommerville, Nystrom, Darley, & Cohen, 2001; Haidt, 2001), the field has experienced an affective revolution that has put emotions at the center of the stage. Although work on exploring role of emotions in assessing morality of various types of moral acts (impure, unfair, etc.; Haidt, 2007) abounds, studying its role in harmful behaviors presents a unique challenge. The aversion to harming others is an integral part of the foundations of human moral sense and it presents itself in the form of deeply ingrained moral intuitions (Haidt, 2007). Since creating laboratory situations to investigate harm aversion raises ethical issues, research has primarily relied on studying hypothetical cases. In the current thesis, we utilize hypothetical vignettes to explore role of emotions in both moral judgment and behavior in harmful contexts, both when harm is carried out intentionally or produced accidentally. Study 1 investigates the role of emotion in motivating utilitarian behavior in moral dilemmas when presented in contextually salient virtual reality format as compared to judgment about the same cases for their textual versions. Study 2 investigates divergent contributions of two different sources of affect, one stemming from self-focused distress and the other focused on other-oriented concern, on utilitarian moral judgments in autistics. Study 3 investigates the role of empathic arousal in condemning agents involved in unintentional harms and why harmful outcomes have a greater bearing on blame as compared to acceptability judgments

Neuroscience in marketing : an FMRI-Based Perspective on brands

Doutoramento em GestãoAlthough somewhat outdated, the American Marketing Association definition of brand still is largely accepted. In this case, brands are signs for product differentiation. The present research, instead, finds brands and their logos as meaningful signs that belong to the human communicative lexicon. Logos are ideograms, i.e. graphic representations that convey meanings. These meanings are transferred from one mind to other minds through brands, establishing communication between humans, and which is also used to self-monitoring in a self-reflexive process, i.e., reading the reactions of others to the ideographic messages once sent to them. Brands are intimately connected to meta-representational processes, whether they are seen as the repository of human attributes, whether themselves are perceived as interlocutors, in a quasi-human level. It also finds that the human emotion system is used to perceive, interpret, and classify brands. Founding in the neuro-based model of emotions developed by Damásio, the present research reveals that brands systematically recruits the emotion system when stimulate brains, which leads to posit that brands are felt in order to be perceived. It is also largely relying in the brain structures that support emotion processing, but also based in other regions that support self-relatedness processing, that is trained an artificial neural network that yields predictions of subjects' choices at a level much higher than mere chance. This procedure allows a coarse but promising consumers' "mind reading".Apesar de algo ultrapassada, a definição de marca da American Marketing Association ainda é largamente aceite. Assim, as marcas são sinais usados na diferenciação de produtos. A investigação presente, pelo contrário, sugere que as marcas e os seus logotipos são sinais com significado que pertencem ao léxico comunicativo humano. Os logotipos são ideogramas, i.e. representações gráficas que transmitem significados. Tais significados transferem-se de uma mente para outra através das marcas, estabelecendo uma comunicação entre humanos, e que também é usada na auto-monitorização num processo auto-reflexivo, i.e. lendo as reacções que os outros têm às mensagens ideográficas que lhes foram enviadas. As marcas estão intimamente ligadas aos processos meta-representacionais, seja por elas serem consideradas um repositório de atributos humanos, seja por elas próprias serem consideradas como interlocutores, a um nível quase-humano. Este estudo também constata que o sistema emocional humano é usado para perceber, interpretar, e classificar as marcas. Baseado no modelo neuronal das emoções de Damásio, verifica-se que as marcas recrutam sistematicamente o sistema das emoções sempre que elas estimulam um cérebro, o que leva a avançar que as marcas são sentidas de forma a serem percebidas. É com base em estruturas cerebrais que sustentam o processamento das emoções, mas também com base em outras regiões ligadas a processamentos da auto-reflexão, que é treinada uma rede neuronal artificial, da qual resultam previsões das escolhas dos sujeitos participantes, as quais estão a um nível muito superior ao mero acaso. Este procedimento permite uma "leitura da mente" algo grosseira, mas muito promissora

Cognitive Architecture, Concepts, and Introspection: An Information-Theoretic Solution to the Problem of Phenomenal Consciousness

This essay is a sustained attempt to bring new light to some of the perennial problems in philosophy of mind surrounding phenomenal consciousness and introspection through developing an account of sensory and phenomenal concepts. Building on the information-theoretic framework of Dretske (1981), we present an informational psychosemantics as it applies to what we call sensory concepts, concepts that apply, roughly, to so-called secondary qualities of objects. We show that these concepts have a special informational character and semantic structure that closely tie them to the brain states realizing conscious qualitative experiences. We then develop an account of introspection which exploits this special nature of sensory concepts. The result is a new class of concepts, which, following recent terminology, we call phenomenal concepts: these concepts refer to phenomenal experience itself and are the vehicles used in introspection. On our account, the connection between sensory and phenomenal concepts is very tight: it consists in different semantic uses of the same cognitive structures underlying the sensory concepts, such as the concept of red. Contrary to widespread opinion, we show that information theory contains all the resources to satisfy internalist intuitions about phenomenal consciousness, while not offending externalist ones. A consequence of this account is that it explains and predicts the so-called conceivability arguments against physicalism on the basis of the special nature of sensory and phenomenal concepts. Thus we not only show why physicalism is not threatened by such arguments, but also demonstrate its strength in virtue of its ability to predict and explain away such arguments in a principled way. However, we take the main contribution of this work to be what it provides in addition to a response to those conceivability arguments, namely, a substantive account of the interface between sensory and conceptual systems and the mechanisms of introspection as based on the special nature of the information flow between them