Figure 9. Long-term potentiation in the insular cortex varies based on sex and subregion.

(A-B)A schematic illustration indicates the alC and pIC, both delineated by red dashed lines. Stimulation and recordings were applied and gathered respectively from layer V pyramidal neurons in each insular cortex. (C-D) An examination of the input-output (I/O) relationship showed a comparable synaptic strength in both the alC and pIC of adult males (C). Conversely, female alC exhibited a greater synaptic strength in comparison to pIC. (E-G) The field excitatory postsynaptic potential (fEPSP), shown as a percentage of the baseline, was observed before and after the application of high-frequency stimulation (HFS). The point in time at which HFS was applied is shown by the arrow. (E) When HFS protocol was administered to layer V pyramidal neurons in adult males, it led to long-term potentiation (LTP) in both the anterior and posterior insular cortices. (F) The fEPSP magnitude at baseline (from 10 to 0 minutes) and during LTP (from 20 to 30 minutes after induction), corresponding to the normalized values in ‘C’, demonstrated a notable difference in the 10-minute baseline period and the final 10 minutes of recording in both male insular cortices. (G) In contrast, the same protocol, when applied in adult females, only induced a strong LTP in the alC. (H) The fEPSP magnitude at baseline (from 10 to 0 minutes) and during LTP (from 20 to 30 minutes post-induction), corresponding to the normalized values in ‘F’, showed a significant difference in the 10-minute baseline period and the final 10 minutes of recording, but only in the alC of adult females. (C-D-E-G) Data are presented as mean ± SEM in XY plots and analyzed via Mann-Whitney U test (C-D). P-values <0.05 are depicted in the graphs. (F-H) Data are shown as pre-post individual experiments and analyzed via Wilcoxon P test. P-values <0.05 are depicted in the graphs. The sample sizes for alC and pIC male and female were 8 and 7, respectively.