The processing of novel stimuli is known to take place in the hippocampus and frontal cortex, and is influenced by the cholinergic system. This ability is crucial to help detect changes in the environment and adapt behaviour accordingly. Previous research has shown that acetylcholine (ACh) can interact with serotonin (5-HT) at the hippocampal level, which may have consequences for cognitive functioning. However, little is known about the exact nature of this ACh and 5-HT interaction as well their possible interactive effects on novelty processing. We investigated the interactive role of ACh and 5-HT in novelty processing in healthy young participants. Levels of these neurotransmitters were manipulated with the muscarinic M1 antagonist biperiden, and with acute tryptophan depletion (ATD). Participants received either placebo, biperiden, ATD, or a combination of both in a double-blind cross-over design. Auditory event-related potentials (ERPs) were recorded while a novelty oddball task was presented. Our results showed that biperiden affected ERP components considered to reflect attentional mechanisms; it increased the P50 amplitude and decreased that of the P200. Furthermore, a decrease of N100 amplitude by ATD was reversed by biperiden. The treatments did not affect the mismatch negativity (MMN) component, which is elicited when a deviant stimulus is presented in a sequence of repetitive stimuli. Importantly, biperiden decreased the amplitude of the ERP component related to novelty processing (P3a). The current study's results did not reveal an interactive effect of ACh and 5-HT on novelty processing. However, the data do suggest that ACh is involved in novelty processing and that it influences basic stimulus processing, without affecting sound-discrimination accuracy.

Outcome measurement is the cornerstone of evidence-based health care including neuropsychological rehabilitation. A complicating factor for outcome measurement in neuropsychological rehabilitation is the enormous number of measures available and the lack of a standard set of outcome measures. As a first step towards such a set, we reviewed intervention evaluation studies of the last 20 years to get an overview of instruments used for measuring outcome. The instruments were divided into two main categories: neuropsychological tests (International Classification of Functioning (ICF) level of functions) and other instruments (all other ICF domains). We considered the most common cognitive domains: memory, attention, executive functions, neglect, perception, apraxia, language/communication and awareness. Instruments used most for measuring outcome were neuropsychological tests (n = 215) in the domains of working memory, reaction times, neglect and aphasia. In the second category (n = 166) the multi-domain instruments were most represented. Several steps can be taken to select a standard set of outcome measures for future use. Next to evaluation of quality and feasibility of the instruments, expert opinion and consensus procedures can be applied.

Many nootropic compounds claim to have positive effects on cognitive performance. In this study, we tested the effects of the nootropic compound CAF+ on cognitive functioning. CAF+ contains a combination of ingredients that has separately shown to boost cognitive performance, including caffeine, l-theanine, vinpocetine, l-tyrosine, and vitamin B 6 /B 12 . We examined whether CAF+ would improve cognitive functions in healthy young participants, and whether it would be more effective than caffeine. We used a randomized double-blind placebo-controlled three-way cross-over design to examine the performance of 21 healthy young participants on a test battery aimed to measure memory performance, attention, and sensorimotor speed. Our main outcome measure was participant's performance on the Verbal Learning Test (VLT). Subjective alertness, heart rate, and blood pressure were also monitored. Participants were tested at 30 and 90 min after treatment. We found that after 90 min, the delayed recall performance on the VLT after caffeine was better than after CAF+ treatment. Further, caffeine, but not CAF+, improved the performance in a working memory task. In a complex choice reaction task caffeine improved the speed of responding. Subjective alertness was increased as a result of CAF+ at 30 min after administration. Only caffeine increased diastolic blood pressure. We conclude that in healthy young students, caffeine improves memory performance and sensorimotor speed, whereas CAF+ does not affect the cognitive performance at the dose tested.

No abstract