Fig. 6: Ventromedial prefrontal cortex and medial temporal lobe responses during recognition of musical sequences for three age groups (young adults, adults between 60 and 68 years of age, adults older than 68).

The black graphs in the NT1 and NT3 plots (all rows) highlight that the strength of the brain prediction error in response to the variation of the original musical sequences was modulated by age. In fact, the strongest signal was recorded for the young adults (n = 37). A reduced prediction error was observed for the adults aged between 60 and 68 (n = 22), while the weakest signal occurred for the adults older than 68 years (n = 17). As observed for the WM in Fig. 5, this effect was particularly evident for the VMPFC and right hippocampal and inferior temporal regions. Note that the figure shows the source localised brain activity illustrated for each experimental condition (M, NT1, NT3) in three (ventromedial prefrontal cortex [VMPFC], left and right hippocampal and inferior temporal regions). Graphs indicates the key event of interest in the brain responses, while the grey areas show the statistically significant differences of the brain activity between the participants grouped in the following three groups: young adults (i), adults between 60 and 68 years of age (ii), adults older than 68 years (iii). Solid line indicates the average over participants, independently for the four groups, while the shaded area the standard errors. The sketch of the musical tones represents the onset of the sounds forming the musical sequences. The brain templates illustrate the spatial extent of the ROIs.