Electrophysiological assessment methodology of sensory processing dysfunction in schizophrenia and dementia of the Alzheimer type.

Schizophrenia and Alzheimer's disease impacts on various sensory processings are extensively reviewed in the present publication. This article describes aspects of a research project whose aim is to delineate the neurobiology that may underlie Social Withdrawal in Alzheimer's disease, Schizophrenia and Major Depression. This is a European-funded IMI 2 project, identified as PRISM (Psychiatric Ratings using Intermediate Stratified Markers). This paper focuses specifically on the selected electrophysiological paradigms chosen based on a comprehensive review of all relevant literature and practical constraints. The choice of the electrophysiological biomarkers were fundamentality based their metrics and capacity to discriminate between populations. The selected electrophysiological paradigms are resting state EEG, auditory mismatch negativity, auditory and visual based oddball paradigms, facial emotion processing ERP's and auditory steady-state response. The primary objective is to study the effect of social withdrawal on various biomarkers and endophenotypes found altered in the target populations. This has never been studied in relationship to social withdrawal, an important component of CNS diseases.

Integration of color and intensity increases time signal stability for the human circadian system when sunlight is obscured by clouds.

The mammalian circadian system encodes both absolute levels of light intensity and color to phase-lock (entrain) its rhythm to the 24-h solar cycle. The evolutionary benefits of circadian color-coding over intensity-coding per se are yet far from understood. A detailed characterization of sunlight is crucial in understanding how and why circadian photoreception integrates color and intensity information. To this end, we continuously measured 100 days of sunlight spectra over the course of a year. Our analyses suggest that circadian color-coding may have evolved to cope with cloud-induced variation in light intensity. We proceed to show how an integration of intensity and spectral composition reduces day-to-day variability in the synchronizing signal (Zeitgeber). As a consequence, entrained phase angle of the circadian clock will be more stable, which will be beneficial for the organism. The presented characterization of sunlight dynamics may become important in designing lighting solutions aimed at minimizing the detrimental effects of light at night in modern societies.