[Techniques for the functional evaluation of neurodevelopmental disorders]

To review the evaluation of neuropsychological functions by using non-invasive functional neuroimaging methods.

Non-invasive functional neuroimaging methods can be sorted into two broad categories: the first includes those that make use of electromagnetic techniques, such as event-related potentials and magnetoencephalography (MEG), and the second consists of those involving haemodynamic techniques, such as positron emission tomography and functional magnetic resonance imaging. These methods have been employed in particular to evaluate the following functions: attention, perception, imagination, language, working memory, semantic retrieval, episodic memory, episodic memory retrieval, priming and procedural memory. The capacity of MEG, both for analysis and for organising the information it receives, is so large that it takes only a few milliseconds to evaluate brain activity and to create functional maps of the brain in which the brain structure is set out in blocks of cubic centimetres or even millimetres. This makes it possible to generate functional maps of brain activity that are capable of being organised and represented in terms of both time and space. It also enables us to obtain images that result from the signalling activity of sets of nerve cells (especially from the dendritic currents) and the electromagnetic signal that carries this information to the outer surface of the head, where the magnetic flow can be recorded.

With the findings from these studies it has become possible to establish a topographic correlation between the functions and the basic brain processes involved in each paradigm. A growing body of clinical evidence proves the value of using them (especially MEG) with cases of epilepsy, language, dyslexia, autism and attention deficit hyperactivity disorder.