The neuropsychophysiological assessment is essential to gain understanding of disorders in the brain function. It consists of a functional exploration technique of the central nervous system (CNS) that produces records of the brain electrical activity in real time. It makes it possible to analyze the cognitive activity, which involves several functions, such as:
  • Identify our environment
  • Reason
  • Among others
  • Understand
  • Integrate
  • Analyze
  • Imagine

The above is essential to conduct an accurate assessment of the cognitive function integrity, the sensory and motor pathways through objective, sensitive, reliable, and safe data. In this way, we can detect alterations present in any of the brain cortex regions, assess the functional interaction among them, complemented by the clinical history of the patient, and establish an accurate diagnosis.

To achieve a complete assessment, it is essential to perform it in wake state, because some tests need to analyze functions that cannot be studied during sleep. Some of the tests, like the electroencephalogram and the P300, can provide us with the information required in that state or during sleep, even when a person is in a coma.

Study characteristics

Painless and non-invasive

and non-invasive

Surface electrodes are attached to the scalp through a conductive gel

Surface electrodes are attached to the scalp through a conductive gel

Approximate duration of 45 minutes

Approximate duration of 45 minutes

They can be performed in patients of any age

They can be performed in patients of any age

The neuropsychophysiological assessment consists
of the following battery of tests

Electroencephalogram (EEG)

It is the fundamental test to detect abnormal activities, like slow activity, paroxysm, or epileptiform activity, associated with epilepsy, but that is present in up to 15 % of the epilepsy-free population.

This epileptiform activity is usually related to activity deficiency of inhibitory or GABAergic neurons, particularly of the chandelier type. 

An important factor worth mentioning is that the information provided by the EEG is not limited to the epilepsy field. An EEG makes it possible to obtain a lot of clinically relevant information in diseases other than epilepsy, like migraines, cerebral ischemic strokes, encephalopathies, head trauma, central nervous system infections, among others.

On the other hand, as the patient is not shown any stimuli nor is he required to perform any task, the EEG is unable to assess the cognitive function. To do it, other tests are required.

Event-related potentials (ERP)

The event-related potentials (ERP) require the analysis of the cognitive activity. There are neurophysiological tests that measure the voltage or power while the patient performs tasks that demand some effort. These are fluctuations in the EEG voltage caused by sensory, motor, or cognitive events. Therefore, to see changes in the EEG a certain stimulus must be presented or a task must be carried out. These changes appear in the form of peaks and provide information about the underlying cognitive processes.

The event- related potentials are essential to assess the brain activity during tasks of:

  • Attention
  • Verbal memory
  • Eye-to-hand memory
  • Idea generation or mental flexibility
  • Oral comprehension
  • Reading comprehension
  • Logical-mathematical processes
  • Movement planning
  • Visuomotricity
  • Emotional processes
Therefore, these assessments have a significant contribution in the diagnosis of disorders, like attention deficit, bipolar disorder, learning problems, neuromotor alterations, etc.


P300 is likely the most important test of this group, where we show the patient an auditory stimulus and define an EEG segment. Within this segment, there will be changes in the brain electrical potential associated specifically with the stimulus. Therefore, it represents one of the evoked potentials and contributes in the assessment of the cognitive function and in the identification of alterations in different regions, particularly in the brain cortex, seen in different diseases, like autism, vascular events (infarctions), trauma, and other types of damages or malformations.

Coherence analysis during the P300

It is required to learn about the functional interaction among brain cortex regions, which is lost in brain lesions caused by different causes, as a result of axon reduction in the regions. This change generates partial or total disconnection, the consequent interaction loss, and the resulting functional deficit. These connections enable communication among the regions, which not only depends on the pyramidal neurons that generate the axons responsible of the connection but only on their regulatory counterparty, that is, the basket cell type GABAergic neurons. These are inhibitory cells responsible for turning off the transmission through the connections, an essential function to send new information packs.

This neuronal type deficit makes it impossible to turn off the transmission, generating significant disorders, like those seen in the most frequent schizophrenia type. Nevertheless, these disorders can be generated as well by exogenous events that affect the population of inhibitory neurons.
Núñez Peña, Isabel, et al. “Potenciales Evocados Cerebrales En El Contexto De La Investigación Psicológica: Una Actualización.” Anuario De Psicología, vol. 35, no. 1, pp. 3–21.

Ramos-Argüelles, F., et al. “Técnicas Básicas De Electroencefalografía: Principios y Aplicaciones Clínicas.” Anales Del Sistema Sanitario De Navarra, vol. 32, no. 3.

Ricardo Garcell, Josefina, & Rueda Medina, Walfred. Electroencefalograma y potenciales relacionados con eventos en el trastorno obsesivo compulsivo. Salud mental, 32(2), 173-181.


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