Neural Basis of Long-term Musical Memory in Cognitively Impaired Older Persons

Abstract

Objective: The objective of this study was to determine whether exposure to long-known music would evoke more extensive activation of brain regions minimally affected by Alzheimer disease (AD) pathology and outside traditional memory networks using a functional magnetic resonance imaging paradigm involving listening to long-known and recently-learned music in older adults with cognitive impairment to provide insight into mechanisms of long-term musical memory preservation in cognitively impaired older persons. Methods: Seventeen subjects with a diagnosis of mild AD or mild cognitive impairment were recruited for this study. Subjects were scanned using functional magnetic resonance imaging while they performed a music listening task, which included short clips of personally selected music from the patient’s past and newly-composed music heard for the first time 60 minutes before scanning. From this task, we obtained group-level maps comparing brain areas associated with long-known and recently-heard music in all subjects. Results: Exposure to long-known music preferentially activated brain regions including the medial prefrontal cortex, precuneus, anterior insula, basal ganglia, hippocampus, amygdala, and cerebellum relative to recently-heard music. These areas are involved in autobiographical memory and associated emotional responses. In addition, they are minimally affected by early stage AD pathology, thus providing a neural basis for long-known musical memory survival. Conclusions: Long-known music activates a bilateral network of prefrontal, emotional, motor, auditory, and subcortical regions (cerebellum, putamen, limbic structures). This extensive activation, relative to recently-heard music, may offer structural and functional clues as to why long-term musical memory appears to be relatively preserved among cognitively impaired older persons.

Effects of transcranial direct current stimulation combined with listening to preferred music on memory in older adults

“…Indeed in the present study, ratings of positive affect increased after listening to autobiographically-salient music in the tDCS + Music condition (where we also observed improvement in working memory from pre- to post-tDCS). This is consistent with past research demonstrating increased arousal in older adults with physiological and subjective measures after listening to familiar individualized music 12 , 63 , 83 , 84 . Transcranial magnetic stimulation of the left DLPFC has also been shown to increase musical reward sensitivity through fronto-striatal pathways 85 .…”

Emotion Processing Dysfunction in Alzheimer’s Disease: An Overview of Behavioral Findings, Systems Neural Correlates, and Underlying Neural Biology

“…76,153,154,157-159 These differences are also reflected in fMRI, with studies reporting amygdala hyperactivity during emotion perception, especially of negative emotion; 177 hippocampal hypoactivity during emotional memory 181 ; and hippocampal along with frontoparietal cortical hypoactivity during complex emotional memory (e.g., autobiographical memory). 182 However, it was noted in a study that the amygdala but not hippocampus was involved in self-referential negative memory. 154 Emotion processing implicates a number of other cortical and subcortical regions, including the prefrontal cortex, pre-/postcentral gyrus, cingulate, insula, and basal ganglia, 42,63,65,161-163 which may be differentially involved in the neuropathology through the course of AD.…”

“…Thus, long-known music activated regions involved in autobiographical memory and emotion processing in AD. 182 However, no control participants were scanned in the latter study. The functional neural correlates of emotional memory are summarized in Figure 7.

Figure 7.Functional correlates of emotional memory in AD.

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“…A study examined how long-known and recently-heard music differentially recruit the emotion circuits in MCI and early AD, and noted activation of bilateral prefrontal, limbic, motor, auditory cortical, and subcortical regions for long-known music. 182 Recently heard vs baseline engaged activation of the inferior frontal gyrus, precentral gyrus, and superior/medial temporal lobe and “deactivation” of the DLPFC and MPFC, including the ACC. Long-known vs baseline and vs recently-heard recruited many of the same regions, as well as the supplementary motor area, precentral gyrus, inferior frontal gyrus, hippocampus, parahippocampus, amygdala, superior/inferior temporal cortex, anterior insula, putamen, pallidum, and anterior thalamus.…”

Age-related variability in network engagement during music listening

“…Working in network space, where the smallest unit of measurement is a network, allows us to examine the shifting patterns of brain activity that accompany music, which has the potential to add nuance that cannot be seen when looking at isolated regions of interest. This approach may also be an important factor in understanding the neural foundation of age-related perceptual changes, and may shed light on why music is so salient in clinical populations (Cuddy & Duffin, 2005; Leggieri et al, 2017; Särkämö et al, 2014; Thaut et al, 2020).…”