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Well known as the center for learning and memory, hippocampus is the crucial brain region to study synaptic plasticity in the context of cellular fundamental mechanisms such as long‐term depression (LTD) and long‐term potentiation (LTP). However, despite years of extensive research, the key to our LTD queries and their induction mechanisms has not been fully understood. Previously, we reported the induction of late‐LTD (L‐LTD) in the distally located synapses of apical branch of hippocampal CA1 dendrites using strong low‐frequency stimulation (SLFS). In contrast synapses at the proximal site could not express L‐LTD. Thus, in the present study, we wanted to investigate whether or not synapses of apical dendritic branch at the proximal location could induce and maintain LTD and its related properties in in vitro rat hippocampal slices. Results indicated that the SLFS in the distal and proximal region triggered the plasticity related proteins (PRP) synthesis in both regions, as evident by the induction and maintenance of L‐LTD in the distal region by virtue of synaptic and cross‐tagging. In addition, the application of emetine at the time of proximal input stimulation prevented the transition of early‐LTD (E‐LTD) into L‐LTD at the distal region, proving PRP synthesis at the proximal site. Further, it was observed that weak low‐frequency stimulation (WLFS) could induce E‐LTD in the proximal region along with LTD‐specific tag‐setting at the synapses. In conclusion, the current study suggests unique findings that the synaptic and cross‐tagging mediate L‐LTD expression is maintained in the proximal location of hippocampus apical CA1 dendrites.

Sex ratio of shoals has been shown to influence shoaling behavior in many fishes. This study tests whether the conspecific identity influences shoal performance (shoal area, interactive distances, distance traveled, and thigmotaxis) of zebrafish (Danio rerio) via group tracking. We conducted a twodimensional analysis of shoals with different sex ratios (male only, female only, male rich, and female rich) of a five-membered shoal. Parameters describing the shoal structure and individual behavior were derived using video tracking and a custom-made program. We found that mixed-sex shoals had significantly lesser shoal area and interactive distance compared to single-sex shoals (approximate difference of 80% for shoal area and 50% for interactive distance). Our findings shed light on complex interactive behaviors of zebrafish in a shoal that are affected by differences in sex ratios of interacting individuals. The outcomes from this study can be used to design better zebrafish shoaling experiments for clinically relevant research like human nerve disorders and social deficits.