Brain Network and Modulation

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Caffeine is the most commonly used stimulant drug in the world. Increasing evidence has indicated that caffeine may have a neuroprotective effect in delaying the onset or treatment of several neurodegenerative disorders, especially Alzheimer's disease (AD). During the progression of AD, accelerated memory loss and cognitive decline are accompanied by two neuropathological hallmarks, the accumulation of amyloid- and tau proteins. The long incubation nature of AD before definitive diagnosis combined with extended duration of life spent with illness contribute significantly to the public health burden, as patients spend much of their end life in a state of severe disability and heavy dependence. Moreover, current drug treatments only provide marginal benefits, creating an urgent need for developing new therapeutic options. There is supportive evidence from clinical trials that caffeine has neuroprotective properties against dementia and AD, but more research is needed to strengthen and confirm these observations. This mini-review presents a short synopsis of the effect of caffeine/coffee on cognition and Alzheimer's disease by evaluating a substantial basis of clinical trials that are related to this topic.

Obsessive-compulsive disorder is a chronic and severe psychiatric disorder with a high prevalence (2–3%) worldwide, of which 30% will be refractory to conventional treatment. Surgical treatment with deep brain stimulation, approved by the U.S. Food and Drug Administration in 2009, seems to be effective in symptomatic control, with response rates exceeding 50% in severely affected patients. However, despite the efficacy indicated in the different studies, surgical treatments for psychiatric disorders are still controversial, and deep brain stimulation for obsessive-compulsive disorder is not yet considered a standard therapy. Since 2009, a wide variety of targets have been suggested for the treatment of obsessive-compulsive disorder; however, to date, there is still no consensus on which target might be optimal for the treatment of obsessive-compulsive disorder. On one hand, authors are trying to find the best target based on each patient and the variability of their symptoms, in an attempt to personalize the treatment. In parallel, there has been a shift in the paradigm of functional neurosurgery from the belief in stimulation focusing on a single target to the modulation of brain circuits or connectomes. With this in mind, it may be possible that many of the targets used in obsessive-compulsive disorder could modulate the same brain network and thus produce an improvement in patients' symptomatology. This study aims to review the evolution of this treatment up to the present time; as well as to make a comparison between these two lines of thought, thus exposing the current state of deep brain stimulation for obsessive-compulsive disorder.

Knowledge about the rhythmic activity of neural networks associated with the implementation of a particular brain function can be used to construct diagnostic systems for objective analyses of cognitive dysfunctions. The aim of this study was to identify specific frequency-based electroencephalogram phenomena associated with speech processing. The study included data from 40 clinically healthy volunteers aged 30 to 50 years (median 32.5 years), including 23 men and 17 women. While listening to a speech stimulus, changes in bioelectrical activity over the speech centers were recorded in 23 subjects (58%). During active speech production, similar changes were recorded in 12 subjects (30%). A pairwise comparison of electroencephalogram frequencies recorded during background recording and listening to the stimuli revealed statistically significant differences in changes in rhythmic activity over Broca’s area during listening and over Wernicke's area during active speech production, while changes in rhythmic activity over Broca’s area during active speech production and over Wernicke's area during listening were less significant. The most characteristic changes in the bioelectrical activity over the speech centers during listening and speaking were fluctuations with a frequency (on average) of 17.5–17.7 Hz. This may reflect a specific electroencephalogram rhythm associated with activity in the speech areas of the brain, which could allow these regions to be more accurately identified during auditory-verbal processing.

Online since 13^th August 2021