Short-term availability of adult-born neurons for memory encoding

Abstract

Adult olfactory neurogenesis provides waves of new neurons involved in memory encoding. However, how the olfactory bulb deals with neuronal renewal to ensure the persistence of pertinent memories and the flexibility to integrate new events remains unanswered. To address this issue, mice performed two successive olfactory discrimination learning tasks with varying times between tasks. We show that with a short time between tasks, adult-born neurons supporting the first learning task appear to be highly sensitive to interference. Furthermore, targeting these neurons using selective light-induced inhibition altered memory of this first task without affecting that of the second, suggesting that neurons in their critical period of integration may only support one memory trace. A longer period between the two tasks allowed for an increased resilience to interference. Hence, newly formed adult-born neurons regulate the transience or persistence of a memory as a function of information relevance and retrograde interference.

Enhanced endogenous activity predicts elimination of adult-born neurons in the mouse olfactory bulb

“…The latter can integrate both the cell-intrinsic firing and the influence of the steady-state odor environment reaching either a pro-or an anti-apoptotic level. Because some odorants increase and others decrease the levels of endogenous activity in JGNs (Homma et al, 2013), this model reconciles the seemingly opposing findings showing that odor enrichment either decreases (Khodosevich et al, 2013) or increases (Forest et al, 2019;Rey et al, 2012;Rochefort et al, 2002) the survival of abJGNs.…”

The Participation of Microglia in Neurogenesis: A Review

“…Various recent studies support the role of microglia in remodeling synaptic connections in the adult hippocampus [ 64 , 65 ]. Indeed, there is direct evidence to suggest that microglia play a role in regulating synaptic competition between newborn neurons and mature granules cells in the adult mice; these adult-born neurons that have replaced pre-existing synapses participate in certain types of memory and learning [ 66 ].…”

Doublecortin-Expressing Neurons in Chinese Tree Shrew Forebrain Exhibit Mixed Rodent and Primate-Like Topographic Characteristics

“…During this neurogenic process, DCX expression initiates following the proliferation of neuronal stem cells and reduces as the newborn neurons differentiate towards morphologically and functionally mature interneurons in the bulb and the excitatory granule cells in the DG (Brown et al, 2003 ). Thus, the presence of DCX+ cells in these two sites represents an active state of neurogenesis, which is considered to play a fundamental role in olfaction, learning and memory, and other cognitive and behavioral functions (Anacker et al, 2015 ; Martinez-Marcos et al, 2016 ; Grelat et al, 2018 ; Danzer, 2019 ; Forest et al, 2019 ; Miller and Sahay, 2019 ; Berdugo-Vega et al, 2020 ).…”