Laboratory of NeuroCognition

These experiments are conducted at the Laboratory of NeuroCognition, School of Psychology of the National Autonomous University of Mexico. The session lasts approximately 2 hours. During the first hour a cap with various electrodes is placed on the head of the participant. The electrodes are small silver discs that are attached to the scalp with an electrolytic paste. The electrodes are connected to a data-collecting system that records the electric activity generated by the brain as the participant performs a task with words or images presented on a computer screen. The encephalographic recording is performed in a sound- dampened chamber in which the participants are seated and in constant communication with the researcher by an interphone and a video circuit. This recording does not represent a health risk.

These experiments are conducted at Institutions where the equipment for this neurophysiological technique is available, such as the National Institute of Neurology and Neurosurgery. The session lasts 45 minutes and participants have to take off metallic object such as belts, keys, coins or credit cards. During the session, the participants perform tasks with words or images as they lie down inside a Magnetic Resonance Imaging scanner. Stimuli are presented through a mirror placed in front of the person inside the scanner. This technique allows to observe the brain regions involved while the person performs a task, through the recording of blood flow. The scanner functions by magnetic fields and radiofrequency pulses that produce maps of water and oxygen concentrations in the body. As the radiofrequency pulses and the magnetic field gradients are emitted, a strong sound is generated in the scanner. This sound is mitigated by earphones. During the experiment, the participants are in constant communication with the researcher through an interphone and a video circuit.

The fMRI technique does not represent a health risk; however, because there are fast and intense changes in the magnetic fields inside the scanner, individuals with metallic devices in the body such as cardiac pacemakers, cochlear implants or tattoos cannot be scanned, because fast changes in radiofrequencies and magnetic fields exert a force on metallic objects, generating heat.