A study published in Science (2009) investigates the role of adult hippocampal neurogenesis in spatial pattern separation. The dentate gyrus (DG) of the hippocampus is thought to mediate pattern separation, which involves forming distinct representations of similar inputs. The study used adult mice with hippocampal neurogenesis ablated by X-irradiation and found impairments in spatial discrimination tasks, particularly when stimuli were presented with little spatial separation. These results suggest that newborn neurons are necessary for normal pattern separation function in the DG. The DG is thought to contribute to spatial or episodic memory by functioning as a pattern separator. Pattern separation is achieved through the dispersion of cortical inputs onto a greater number of dentate granule cells (DGCs) with small place fields. DGCs are particularly adapted to maintain and transmit orthogonalized information, which is important for accurate memory encoding. Behavioral studies showed that mice with ablated neurogenesis were impaired in tasks requiring spatial discrimination but not in associative memory tasks. Adult neurogenesis is ongoing in the DG and is thought to play a role in learning and memory. However, its contribution to hippocampal function remains unclear. The study used two independent methods to ablate neurogenesis: X-irradiation and lentiviral expression of dominant negative Wnt. Both methods resulted in impairments in spatial pattern separation tasks but not in associative memory tasks. The results suggest that adult hippocampal neurogenesis is important for the ability of the DG to perform pattern separation optimally. The study also indicates that immature neurons may contribute to pattern separation directly or through more complex interactions within the DG circuitry. The findings highlight the importance of neurogenesis in spatial memory and provide experimental evidence of a role for newborn neurons in the adult DG in spatial discrimination.A study published in Science (2009) investigates the role of adult hippocampal neurogenesis in spatial pattern separation. The dentate gyrus (DG) of the hippocampus is thought to mediate pattern separation, which involves forming distinct representations of similar inputs. The study used adult mice with hippocampal neurogenesis ablated by X-irradiation and found impairments in spatial discrimination tasks, particularly when stimuli were presented with little spatial separation. These results suggest that newborn neurons are necessary for normal pattern separation function in the DG. The DG is thought to contribute to spatial or episodic memory by functioning as a pattern separator. Pattern separation is achieved through the dispersion of cortical inputs onto a greater number of dentate granule cells (DGCs) with small place fields. DGCs are particularly adapted to maintain and transmit orthogonalized information, which is important for accurate memory encoding. Behavioral studies showed that mice with ablated neurogenesis were impaired in tasks requiring spatial discrimination but not in associative memory tasks. Adult neurogenesis is ongoing in the DG and is thought to play a role in learning and memory. However, its contribution to hippocampal function remains unclear. The study used two independent methods to ablate neurogenesis: X-irradiation and lentiviral expression of dominant negative Wnt. Both methods resulted in impairments in spatial pattern separation tasks but not in associative memory tasks. The results suggest that adult hippocampal neurogenesis is important for the ability of the DG to perform pattern separation optimally. The study also indicates that immature neurons may contribute to pattern separation directly or through more complex interactions within the DG circuitry. The findings highlight the importance of neurogenesis in spatial memory and provide experimental evidence of a role for newborn neurons in the adult DG in spatial discrimination.