Vagus nerve stimulation improves working memory performance

Abstract

Vagus nerve stimulation (VNS) is used for treating refractory epilepsy and major depression. While the impact of this treatment on seizures has been established, its impact on human cognition remains equivocal. The goal of this study is to elucidate the immediate effects of vagus nerve stimulation on attention, cognition, and emotional reactivity in patients with epilepsy. Twenty patients (12 male and 8 female; 45 ± 13 years old) treated with VNS due to refractory epilepsy participated in the study. Subjects performed a computer-based test of executive functions embedded with emotional distractors while their brain activity was recorded with electroencephalography. Subjects' cognitive performance, early visual event-related potential N1, and frontal alpha asymmetry were studied when cyclic vagus nerve stimulation was on and when it was off. We found that vagus nerve stimulation improved working memory performance as seen in reduced errors on a subtask that relied on working memory, odds ratio (OR) = 0.63 (95% confidence interval, CI [0.47, 0.85]) and increased N1 amplitude, F(1, 15) = 10.17, p = .006. In addition, vagus nerve stimulation resulted in longer reaction time, F(1, 16) = 8.23, p = .019, and greater frontal alpha asymmetry, F(1, 16) = 11.79, p = .003, in response to threat-related distractors. This is the first study to show immediate improvement in working memory performance in humans with clinically relevant vagus nerve stimulation. Furthermore, vagus nerve stimulation had immediate effects on emotional reactivity evidenced in behavior and brain physiology.

Effect of neurostimulation on cognition and mood in refractory epilepsy

“…Another study of 20 subjects investigating the effects of VNS on attention, cognition, and emotional reactivity found that subjects had improved working memory performance with VNS . More specifically, patients were presented with a triangle pointed upward or downward and had to recall its orientation when prompted by a visual cue.…”

Coupling of autonomic and central events during sleep benefits declarative memory consolidation

“…Lesions of the vagus nerve impair memory 12 , whereas pairing vagal nerve stimulation with auditory stimuli reorganizes neural circuits 43 , strengthens neural response to speech sounds in the auditory cortex 44 , and enhances extinction learning of fear memories in rodents 45 . In humans, vagal nerve stimulation enhances consolidation of verbal memory 13 and working memory 46 . Recently, Whitehurst and colleagues used traditional methods to detect total sympathetic and parasympathetic power of the HRV signal during sleep and showed a correlation between parasympathetic activity during REM sleep (but not SWS) and implicit learning 14 .…”

Research progress of vagus nerve stimulation in the treatment of epilepsy

“…The overall effect of VNS on cognition is unclear, and many studies focus on memory. There is an evidence that VNS treatment can acutely improve memory in a short time, but there seems to be no significant improvement within the long‐term treatment . Orosz et al surveyed the effects of VNS treatment on 347 pediatric patients, evaluating the different aspects of cognition such as memory, concentration, alertness, language communication, and academic progress at 12 and 24 months.…”

“…There is an evidence that VNS treatment can acutely improve memory in a short time, but there seems to be no significant improvement within the long-term treatment. [44][45][46] Orosz et al 31…”