Overview of the lab's research projects
In sport, science, economy, and shopping we use numerical information to guide our behaviour. How do we understand numbers? What are the cognitive architectures and neural mechanisms that subserve such ability? And why some people find it intuitive while others struggle with it on a daily basis? We focus on human abilities and disabilities to perceive, represent, learn, and manipulate information about numbers. To do so we use typical and special populations (participants with developmental dyscalculia), and a variety of behavioural paradigms and neuroscientific methods such as fMRI, and non-invasive brain stimulation techniques (transcranial magnetic stimulation (TMS), transient direct current stimulation (tDCS)).
Cognitive Enhancement and Brain Plasticity
What makes some people achieve exceptionally high cognitive ability levels, such as in mathematics for example? We address this question by using a variety of neuroimaging methods. In a series of studies, we use learning paradigms together TDCS to induce brain plasticity and enhance basic numerical abilities as well as arithmetics. Moreover, we currently examine the acquisition of numerical abilities in typical and special populations (using brain stimulation and fMRI), and thus combine our basic to applied research with neuroscientific methods.
Specialisation in the Brain
Number systems are greatly affected by culture and education. To investigate how the brain becomes specialised to deal with numerical information, we use a variety of neuroimaging techniques and special populations (participants with number-colour synaesthesia). We have shown in previous studies that although numbers are processed by the same brain areas that are sensitive to other non-numerical magnitudes, such as size or luminance, numbers are subserved by specialised neuronal substrates that spatially overlap with other dimensions. Moreover, our findings have established that even within numbers, there is specialisation for different formats, i.e., there are distinct neuronal substrates for digits, verbal numbers, etc that are co-localised at close proximity. As this co-localisation cannot be detected by conventional methods, we have developed a range of (adaptation) paradigms coupled with fMRI and TMS that can detect these distinct, but overlapping neuronal representations in the brain. In addition, we have used effective connectivity as a tool to disentangle neuronal specialization in brain areas that are commonly activated.
Synaesthesia is a fascinating condition in which certain stimuli (e.g., sounds) or concepts (e.g., words, numbers) automatically evoke additional percepts (e.g., colour). It was once believed that synaesthesia is unidirectional. For example, it has been suggested that numbers can trigger the perception of colour, but not vice versa. In our research, we have provided some novel evidence, at the level of brain and behaviour, that challenges this view by showing convincingly that synaesthesia can be bidirectional. We also found that synaesthesia is not idiosyncratic, in contrast to the commonly held view, but follows a perceptual organisation. This might be due to a lack of cortical specialisation during infancy and childhood. Recently, we have been working towards discovering the underlying mechanism that triggers synaesthesia. Using posthypnotic suggestion we established that in contrast to the anatomical theory of synaesthesia, synaesthetic behaviour can occur without abnormal anatomical connections, probably due to a lack of cortical inhibition. We also use synaesthsia to examine implicit processes in the general population, in which synaesthetes have conscious access to these processes (e.g., number-form synaesthesia).
Automaticity and Cognitive Control
We process different stimuli, such as words or numbers, in our environment without consciously monitoring this. Sometimes processing these stimuli can be in conflict with other stimuli that are more important for our goal. In a series of studies, we examined how the brain mechanisms and the timing of the conflict between different dimensions is affected by task load. In addition, we used functional connectivity analysis to unravel the different interacting brain networks that enable optimal performance. Finally, we have begun to investigate the contribution of the dorsolateral prefrontal cortex (DLPFC) and the parietal lobes in automaticity and skill acquisition.