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					 page 36          Lab Times        3-2010                                                                                           Journal Club




Hippocampal plasticity in Bern and Basle


Let the Music Play
Are musicians born or can training make a musician of almost everyone?
A group of Swiss brain scientists, at least, were able to show that functional
plasticity in the human hippocampus can be induced by music.


N
          obel laureate and organist Albert            Functional plasticity is another impor-
          Schweitzer once said, “Joy, sorrow,      tant property attributed to the hippocam-
          tears, lamentations, laughter – to       pus as shown by indirect studies (Maguire
all these music gives voice, but in such a         et al., 2000; Draganski et al., 2006). How-
way that we are transported from the world         ever, no direct evidence has been reported
of unrest to the world of peace, and see re-       so far which would directly link changes in
ality in a new way, as if we were sitting by a     hippocampal processing to certain training
mountain lake and contemplating hills and          exercises. Therefore, a new study by Mar-
woods and clouds in the tranquil and fath-         cus Herdener et al. in which they show that
omless water.” But one question has per-           functional plasticity in the human hippoc-
sisted up until today: Are musicians born          ampus is induced by music can be regarded
or can training make a musician of almost          as a real first (J. Neurosci. vol. 30(4):1377-
everyone? A group of psychiatrists, physi-         84).
cists and neuroscientists from Basle, Bern,            Analyses of whole human brains us-
Naples and Zurich have been approaching            ing functional Magnetic Resonance Imag-
this problem by investigating the impact of        ing (fMRI) have revealed the role of the          ic one”. One of the co-authors has a mu-
musical training on our brains.                    right hippocampus as one of the major re-         sician husband with contacts at the Basle
                                                   gions of retrieval success for music memo-        music school which helped them approach
                                                   ry. At the same time, the hippocampus has         academic staff and students. In this way,
    The hippocampus, part of the cerebral          also been associated with novelty detection       recruiting participants for the study was
hemisphere, has the shape of a sea horse --        based on the comparison of actual sensory         not difficult apart from a small initial con-
hence the name hippocampus. In the adult           inputs with stored stimulus patterns. Thus,       cern about fMRI. In fact, the students were
brain, it is an important structure for the        Herdener et al. decided to perform a study        very happy to be a part of the study and the
formation of certain types of memory, such         based on the hypothesis that the hippoc-          teachers even more so. They were them-
as episodic memory and spatial memory,             ampus might play a crucial role in the de-        selves curious to “see” the consequences of
and is linked to the detection of novelty in       tection of novelty of temporal structures         their teaching on their students’ brains!
our environment.                                   in the auditory domain. If true, then fine
                                                          tuning these aural skills by training
                                                          might modulate the detection of tem-            But first of all, Herdener et al. had to
                                                          poral novelty of acoustic signals in the   explain to them the principles of fMRI and
                                                          hippocampus.                               how the haemodynamics in the brain are
                                                              Since music students usually re-       linked to neural activity. When neural cells
                                                          ceive a sophisticated aural train-         are active, the vascular system increases the
                                                          ing during their education, Marcus         oxygen supply via neurovascular coupling.
                                                          Herdener and his colleagues chose to       This leads to an excess in local oxyhemo-
                                                          use the brains of musicians as a mod-      globin levels in the vessels of active regions
                                                          el to test for training-induced plastic-   leading to changes in the local ratio of oxy-
                                                          ity of the adult human hippocampus.        hemoglobin to deoxyhemoglobin. This ra-
                                                                                                     tio is therefore the marker of blood oxygen
                                                                                                     level-dependent (BOLD) activity as meas-
                                                              After his MD studies at the Uni-       ured with fMRI. Thus, BOLD is an indirect
                                                          versity of Freiburg, Germany, Marcus       parameter for neural activity.
                                                          moved to the University Hospital of             In a cross-sectional study, the authors
                                                          Psychiatry in Bern, Switzerland, for       first presented a temporal mismatch para-
                                                          clinical training. “Here, the project      digm to professional musicians as well as to
                                                          was kick started by Katja Cattapan-        musical laypeople. This consisted of sounds
                                                          Ludewig and Erich Seifritz, both co-       with a regular temporal pattern interrupt-
Getting music not only in their brains: Benedikt Hab-     authors of the paper,” he says with a      ed by infrequently occurring tones with de-
ermeyer (top left), Fabrizio Esposito (top right), Mar-   big smile. “There was a personal link      viant standard stimulus onset asynchrony
cus Herdener (bottom left), Katja Cattapan (centre)       to this project as much as a scientif-     (SOA, i.e. creating a slightly irregular tem-
 Journal Club                                        3-2010        Lab Times         page 37




         poral pattern). The occurrence          not receive any aural training between the
         of standard sine tones, presented       two evaluations.
         with shorter SOAs (142, 130, 100             The results showed that a general au-
         ms) compared to the standard SOA        ral training increased neural activity (BOLD
         (150 ms), thus elicited a mismatch      activity) in LAH, both in professionals and
         response in the temporal plane of       musical students. The study further indi-
         the right hemisphere (which is a        cated that the BOLD activity in the Planum
         part of the human auditory cor-         temporale, induced by temporal mismatch,
         tex), depending on the degree of        did not differ between musicians and non-
         deviance. The greater the deviance      musicians. This is true in both cases: the
         (i.e. shorter deviant SOAs), the        cross-sectional comparison of professional
         more neural activity was induced.       musicians versus non-musicians and in the
              A general problem of fMRI of       longitudinal study on the impact of musical
         the auditory system is the nonspe-      training on acoustic novelty detection. This
         cific hammering sound produced          indicates a comparable detection of tempo-
         by the MR unit while in function.       ral novelty in secondary auditory regions of
         This noise is about 90 dB and can       both musicians and non-musicians.
         cause severe changes of activi-              The most important outcome of the
         ty in the auditory system result-       study, however, was that music students
         ing in a read out, which is main-       show enhanced BOLD activity to temporal
         ly due to the background noise. So      novelty in the LAH (where they also found
         Herdener et al. created a new MR-       functional differences between profession-
         sequence, whereby this noise was        al musicians and non-musicians) only af-
         reduced. This way, a better percep-     ter receiving aural skills training, suggest-
         tion of the experimental sound was      ing that training indeed induced changes
         enabled and the signal-to-noise ra-     in sound pattern-processing. Furthermore,
tio for the measurements was greatly en-         the authors showed that the observed train-
hanced.                                          ing-related changes in hippocampal activi-
    The study finally showed that the BOLD       ty are correlated with students’ perform-
activity in the Planum temporale of the          ance in music dictation, a commonly used
right hemisphere, induced by a temporal          test to evaluate the individual’s aural skills,
mismatch, did not differ significantly be-       pointing to the behavioral relevance of hip-
tween musicians and non-musicians. But           pocampal plasticity in musical education.
a two-way interaction analysis of ‘tempo-             Since others have previously shown that
ral novelty’ and ‘musicianship’ (professional    training can also have so-called ‘transfer-
musicians vs. non-musicians) revealed en-        effects’ as well as improve cognitive func-
hanced BOLD responses to novelty of tem-         tions not directly linked to training, it will
poral structure in the left anterior hippoc-     be of great interest to see if such hippocam-
ampus (LAH) of musicians.                        pal plasticity, as found in musicians, also in-
    The study’s aim was to test the involve-     fluences, for example, memory functions.
ment of the hippocampus in acoustic nov-
elty detection and its functional modula-
tion in musical experts. But this set-up cer-         We have finally come to potential thera-
tainly doesn’t answer all questions such as,     pies. For several brain-related problems mu-
for example, whether the differences ob-         sic proves to be a good therapy. Särkämö T
served between the groups are related to         et al., for example, demonstrated that after
talent or training.                              neural damage by stroke, listening to mu-
                                                 sic, in contrast to speech, can induce plastic
                                                 changes in early sensory processing, which
    Therefore, in a second longitudinal set-     in turn might even facilitate the recovery of
up, the authors presented the temporal mis-      higher cognitive functions (J. Cogn. Neuro-
match paradigm from the first experiment         sci., Epub ahead of print Nov. 2009). Simi-
to an independent sample of music students       larly, music can apparently exert significant
and students from other faculties. The aim       impact on schizophrenia patients.
of this experiment was to evaluate the im-            Therefore, Herdener himself is now
pact of academic musical training on tem-        planning to study the effect of music-relat-
poral novelty detection. Hence, BOLD re-         ed brain plasticity in patients suffering from
sponses to temporal novelty were measured        psychiatric diseases. And for this reason his
twice in both groups (before and after mu-       answer to all of us who think it’s too late to
sical training). In contrast to the music stu-   learn music, is a clear “No”.
dents, the students from other faculties did                       Vasudharani Devanathan

				
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