Assessment of Audio-Tactile Sensory Substitution Training in Participants with Profound Deafness Using the Event-Related Potential Technique.

This paper examines the application of electroencephalogram-based methods to assess the effects of audio-tactile substitution training in young, profoundly deaf (PD) participants, with the aim of analyzing the neural mechanisms associated with vibrotactile complex sound discrimination. Electrical brain activity reflects dynamic neural changes, and the temporal precision of event-related potentials (ERPs) has proven to be key in studying time-locked processes while performing behavioral tasks that involve attention and working memory. The current protocol was designed to study electrophysiological activity in PD subjects while they performed a continuous performance task (CPT) using complex-sound stimuli, consisting of five different animal sounds delivered through a portable stimulator system worn on the right index finger. As a repeated-measures design, electroencephalogram (EEG) recordings in standard conditions were performed before and after a brief training program (five 1 h sessions over 15 days), followed by offline artifact correction and epoch averaging, to obtain individual and grand-mean waveforms. Behavioral results show a significant improvement in discrimination and a more robust P3-like centroparietal positive waveform for the target stimuli after training. In this protocol, ERPs contribute to the further understanding of learning-related neural changes in PD subjects associated with audio-tactile discrimination of complex sounds.

[Dysthymia in the Clinical Context]. / La distimia en el contexto clínico.

Dysthymia is defined as a chronic mood disorder that persists for at least two years in adults, and one year in adolescents and children. According to DSM IV-TR, Dysthymia is classified into two subtypes: early-onset, when it begins before 21 years-old, and late onset Dysthymia, when it starts after this age. Before age 21, symptoms of conduct disorder, attention deficit disorder and hyperactivity with a few vegetative symptoms are usually present. It is important to distinguish it from other types of depression, as earlier as possible. This would allow providing these patients with the appropriate treatment to attenuate the impact of symptoms, such as poor awareness of self-mood, negative thinking, low self-esteem, and low energy for social and family activities, which progressively deteriorate their life quality. The etiology of Dysthymia is complex and multifactorial, given the various biological, psychological and social factors involved. Several hypotheses attempt to explain the etiology of Dysthymia, highlighting the genetic hypothesis, which also includes environmental factors, and an aminergic hypothesis suggesting a deficiency in serotonin, norepinephrine and dopamine in the central nervous system. From our point of view, dysthymia cannot be conceived as a simple mild depressive disorder. It is a distinct entity, characterized by a chronic depressive disorder which could persist throughout life, with important repercussions on the life quality of both patients and families.