Altered inhibitory function in hippocampal CA2 contributes in social memory deficits in Alzheimer's mouse model.

Parvalbumin (PV)-expressing interneurons which are often associated with the specific extracellular matrix perineuronal net (PNN) play a critical role in the alteration of brain activity and memory performance in Alzheimer's disease (AD). The integrity of these neurons is crucial for normal functioning of the hippocampal subfield CA2, and hence, social memory formation. Here, we find that social memory deficits of mouse models of AD are associated with decreased presence of PNN around PV cells and long-term synaptic plasticity in area CA2.

Maturation of PNN and ErbB4 Signaling in Area CA2 during Adolescence Underlies the Emergence of PV Interneuron Plasticity and Social Memory.

Adolescence is a vulnerable period characterized by major cognitive changes. The mechanisms underlying the emergence of new cognitive functions are poorly understood. We find that a long-term depression of inhibitory transmission (iLTD) from parvalbumin-expressing (PV+) interneurons in the hippocampal area Cornu Ammonis 2 (CA2) is absent in young mice but emerges at the end of adolescence.

Early disruption of parvalbumin expression and perineuronal nets in the hippocampus of the Tg2576 mouse model of Alzheimer's disease can be rescued by enriched environment.

Recent findings show that parvalbumin (PV) interneuron function is impaired in Alzheimer's disease (AD), and that this impairment in PV function can be linked to network dysfunction and memory deficits. PV cells are often associated with a specific extracellular matrix, the perineuronal net (PNN). PNNs are believed to protect PV cell integrity, and whether the amyloidopathy affects PNNs remains unclear.