Janata based his hypothesis that the MPFC would be at the center of activity on several previous studies that showed it to be involved in autobiographical memory retrieval. In several of his own earlier studies, Janata had observed that the MPFC is used to track music through tonal space, and that music serves as a powerful retrieval cue for autobiographical memories. Another compelling study showed that the MPFC atrophies more slowly than other brain areas in patients with Alzheimer’s disease, and that memory for familiar music is something that these patients retain longer than many other memories.
There were two hypotheses being tested in this experiment: the first is that activity in the MPFC would show positive correlation to the familiarity, autobiographical salience, and positive affect brought about by the music. The second was that overlapping areas, of those in close proximity to those demonstrating positive correlation, would track the musical excerpts through tonal space. For the sake of time, I will address the first hypothesis.
Method:
Janata’s study involved 13 students at UC Davis. Using songs from the Top 100 charts from when the subjects were between 7 and 19 (to ensure there would be some familiarity with the songs), Janata used fMRI scans to monitor their brains while they listened to 30 second excerpts from 30 different songs.
Following each excerpt, subjects pressed buttons on a keypad to respond to questions about the valence (how pleasant the music was) and arousal while listening to the clip, their familiarity with the song, whether it held any particular autobiographical associations for them, the orientation of their attention to those associations/memories, and the orientation of their attention to the music itself. After the fMRI monitoring, subjects completed a survey about the memories they had experienced while listening to the song excerpts.
Results:
From the 17 songs that the subjects remembered on average, 13 had moderate to strong associations to autobiographical memories. Songs that had the strongest associations also evoked the most emotional, vivid responses. In the fMRI images, these memories corresponded to activity in the upper part of the MPFC.
This shows the results of the ratings the subjects assigned to each song excerpt. Black represents the most negative value for each scale, and white represents the most positive.
Abbreviations: STG, superior temporal gyrus; DLPFC, dorsolateral prefrontal cortex; DMPFC, dorsomedial prefrontal cortex; VLPFC, ventrolateral prefrontal cortex; VMPFC, ventromedial prefrontal cortex; IFG, inferior frontal gyrus; FO, frontal operculum; IPS, intraparietal sulcus; AG, angular gyrus; pSMA, presupplementary motor area; ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; IFS, inferior frontal sulcus; MFG, middle frontal gyrus; Ins, insula; SPL, superior parietal lobule; Cb, cerebellum; PT, planum temporale; vltn, ventral lateral thalamic nucleus; and MTG, middle temporal gyrus.
In these images, you can see brain activity during different phases of the experiment: music playing, question-answer period, and the effects of familiarity, autobiographical salience, and valence. FAV represents “the combined effects of hearing pleasing, familiar, and autobiographically salient songs relative to unfamiliar, emotionally neutral, or displeasing songs that elicited no autobiographical association.” These images show the concentration of activity related to associations in the prefrontal cortex, as well as the left-hemispheric bias (the negative numbers refer to the left hemisphere).
In this second set of images, you can see the individual effects of familiarity, autobiographical salience, and valence, showing the same trends as the first set of images.
Implications:
Janata’s results show that the MPFC is key in associating familiar music with autobiographical memories. Importantly, it links structural characteristics of a retrieval cue with episodic memories (in spontaneous, rather than effortful, retrieval). This builds on existing knowledge of autobiographical memory by demonstrating the “spontaneous activation of an autobiographical memory network in a naturalistic task with low retrieval demands.”
Although Janata’s study itself did not suggest the uses or applications of this discovery, he is quoted in the ScienceDaily article as saying that a long-term goal for this new knowledge was to use music to improve Alzheimer’s patients’ quality of life.
Sources:
Janata, P. (2009). The Neural Architecture of Music-Evoked Autobiographical Memories. Retrieved February 24, 2009, from Cerebral Cortex Website: http://cercor.oxfordjournals.org/cgi/content/full/bhp008v1#ABS
Nervous System. Retreived March 1, 2009, from A Review of the Universe Web site: http://universe-review.ca/R10-16-ANS.htm
University of California - Davis (2009, February 24). Brain Hub That Links Music, Memory And Emotion Discovered. Retrieved February 24, 2009, from Science Daily Web site: http://www.sciencedaily.com/releases/2009/02/090223221230.htm
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