Interesting research report:
Hyperactivity of the human anterior hippocampus has been reported to spread from its CA1 subfield to the subiculum around the onset of first-episode psychosis and could be a cellular target for early therapeutic intervention in the schizophrenia prodrome. However, to what extent CA1 hyperactivity actually causes schizophrenia-related symptoms remains unknown. Here, we mimic this endophenotype by direct optogenetic activation of excitatory cells in the homologous mouse region, ventral CA1 (vCA1) and assess its consequence in multiple schizophrenia-related behavioural tests. We find that hyperactivity of vCA1 causes hyperlocomotion and impairments of spatial and object-related short-term habituation (spatial novelty-preference and novel-object recognition memory) and spatial working memory, whereas social interaction, spatial exploration, and anxiety remain unaltered. Stimulation of the ventral subiculum, in contrast, only increased locomotion and exploration. In conclusion, CA1 hyperactivity may be a direct driver of prodromal cognitive symptoms and of aberrant salience assignment leading to psychosis.
From the Discussion section:
We here demonstrated, that optogenetically induced elevated excitatory activity in the corresponding ventral CA1 region in mice can induce a range of deficits related to the control of selective attention and salience attribution, as well as to short-term and working memory, each of which is central to positive or cognitive symptoms, respectively, displayed in the prodrome and in overt schizophrenia1,15. In contrast, sociability, which is also impaired in prodromal individuals44, was not affected by vCA1-hyperactivity, although other tests of sociability are warranted in this model to confirm this conclusion, in future. Overall, our study confirms that elevated CA1-activity in the prodrome may be a direct cause of cognitive deficits in this phase43—in line with results with more broad vHC activation and disinhibition1,24,27.
The salience concept is quite interesting and important for psychosis research - just google for “salience and psychosis”.