Asenapine maleate normalizes low frequency oscillatory deficits in a neurodevelopmental model of schizophrenia.

Asenapine maleate (AM) is an atypical antipsychotic that, unlike many other antipsychotics, shows some efficacy in treating cognitive dysfunction in schizophrenia. Normal cognitive function has long since been associated with high frequency neuronal oscillations. However, recent research has highlighted the potential importance of low frequency oscillations. Here, the impact of AM on low frequency neural oscillatory activity was evaluated in the methylazoxymethanol acetate (MAM) rat model system used for the study schizophrenia, and the oscillatory signatures compared to those of haloperidol (HAL) and clozapine (CLZ). AM and CLZ normalized low frequency spectral power deficits in the prefrontal cortex, while HAL and AM reversed corticostriatal and corticocortical delta coherence deficits. However, only chronic AM administration normalized corticostriatal and corticocortical delta coherence deficits between 3-4 Hz. These findings support the idea that antipsychotic-induced amelioration of both delta coherence and power may be important for therapeutic efficacy in treating the cognitive deficits inherent in schizophrenia.

Development of an "object category recognition" task for mice: Involvement of muscarinic acetylcholine receptors.

Recent research suggests that rats are capable of object categorization-like processes. To study whether mice possess similar abilities, we developed a spontaneous one-trial object category recognition (OCR) task. Based on the spontaneous object recognition paradigm, mice discriminated between two otherwise equally novel objects, one from a novel category and one from a studied category. During the sample phase, mice were exposed to two different exemplars from the same category. After a retention delay, they explored a third (i.e., novel) object from that sampled category and an object from a novel category in a choice phase. Mice preferentially explored the novel category object, taken as an index of category recognition, in this OCR task when a 30-min retention delay was used. Extensive preexposure to category exemplar objects also enhanced subsequent task performance across a longer (1-h) retention delay at which mice without preexposure did not demonstrate evidence for category recognition. Prechoice administration of the acetylcholine muscarinic receptor antagonist, scopolamine, disrupted OCR performance with or without preexposure, implicating acetylcholine in category recognition. The current study presents a valuable new rodent task for the study of the mechanistic basis of categorization-like processes and its potential relevance to common cognitive disorders. (PsycINFO Database Record (c) 2019 APA, all rights reserved).