‘Pay attention!’ ‘I can’t concentrate’, ‘You’re not paying enough attention’ and so on... The concept of attention is a common topic of conversation. And we all have a vague idea of what it means. But how exactly do neuroscientists define it? How does it originate in the brain? What research is conducted into this area at Paris Brain Institute?
‘Attention is the taking possession by the mind, in clear and vivid form, out of what seem several simultaneously possible objects or trains of thought [...] It implies withdrawal from some things in order to deal effectively with others’: this is how the founder of US psychology, William James (1842–1910), defined attention as early as the 1890s in his book ‘The Principles of Psychology’. In other words, this function refers to the brain’s capacity to selectively focus on a targeted and relevant aspect of its environment while ignoring other, less important things; in the knowledge that our ability to process information from our sense organs (eyes, ears, etc.) is limited.
Attention keeps us focused and alert. Whether for memorisation, problem-solving, reading or even decision-making, most of the brain’s activities require strong concentration.
For example, this is the cognitive ability that enables us to focus on learning in class, reading on the train without being distracted by the flow of passengers getting on and off at each stop, stopping our car at red lights without being distracted by the billboards flashing next to us and following a conversation amid the noise of a crowded restaurant. This indicates the importance of attention to our perception of the world, our interactions with others and behaviours adapted to our environment.
Several studies have shown that attention is not, in fact, a single cognitive process, but instead the sum of several interconnected processes. Neuroscientists have identified several of them. Referred to as ‘attentional intensity’, in this process we direct a certain amount of attention resources towards a task. This explains why we can suddenly and momentarily (for a few seconds) increase our level of alertness following a change in our environment (noise, someone entering the room, etc.). This function is called ‘phasic alertness’. Or why you can, by contrast, maintain a high level of attention for many minutes, or even hours (‘sustained attention’). ‘Selective attention’, meanwhile, protects you against cognitive overload, by focusing only on relevant information. This is what causes attention resources to be directed towards a single meaningful stimulus (‘focused attention’) or on two tasks performed simultaneously (‘divided attention’). Finally, another process, ‘attentional control’, enables you to choose what you focus on and what you ignore.
As summarised by clinical neurologist and neuroscientist Paolo Bartolomeo in his book ‘Penser droit’ (éditions Flammarion [in French], 2020) attention does not originate from a specific area of the brain but instead from vast neuronal networks called ‘frontoparietal networks’. As their name suggests, these networks extend from the frontal cortex (forehead area) to the parietal cortex (under the parietal bone that forms the cranial vault, the back and upper parts of the skull). Located far away in the brain, these areas are interconnected by large bundles of nerve fibres. Linked to neuron extensions called axons, which transmit electrical signals between nerve cells, these nerve ‘highways’ allow quick and effective communication between these areas of the brain. Note that, in general, each brain hemisphere directs attention to the opposite side, thanks to a ‘dorsal’ neuronal network of attention located at the top of the brain. A ‘ventral attention network’ further down in the brain and lateralised to the right hemisphere allows us to identify important objects and direct our attention towards them.
Our attention spans can be weakened by several factors. The first factor is ageing, which is accompanied by a drop in attentional resources and greater sensitivity to interruptions. But attention can also wane at any age when tired, stressed or after drinking too much alcohol. This faculty can also be deficient in several ‘innate’ neurological disorders that appear from early childhood, such as autism and attention deficit hyperactivity disorder (ADHD), which affect our concentration and ability to ignore distractions. Finally, attention can also be affected by disorders ‘acquired’ during life, such as hemineglect, also known as ‘unilateral spatial neglect’. In most cases onset occurs after a stroke in the right hemisphere of the brain, and presents as problems with detecting objects or information positioned on the left because of an attention deficit for that side.
Attention is a core focus of the work by a team at Paris Brain Institute: the ‘Neuropsychology and functioning Neuroimaging’ group, abbreviated to PICNIC (‘Physiological Investigations of Clinically Normal and Impaired Cognition’). Its core research focuses include studying the brain’s mechanisms in the orientation of spatial attention in healthy people or people affected by hemineglect. To carry out their work, the researchers use several state-of-the-art techniques: in particular, neurophysiological techniques such as intracerebral recordings and magnetoencephalography (MEG), which measures magnetic fields induced by the electrical activity of neurons; neuroanatomical methods such as high-resolution MRI; and behavioural tests such as the study of manual response times and eye tracking.