Efficacy of a music-based intervention in a preclinical model of traumatic brain injury: An initial foray into a novel and non-pharmacological rehabilitative therapy

Abstract

Traumatic brain injury (TBI) causes neurobehavioral and cognitive impairments that negatively impact life quality for millions of individuals. Because of its pernicious effects, numerous pharmacological interventions have been evaluated to attenuate the TBI-induced deficits or to reinstate function. While many such pharmacotherapies have conferred benefits in the laboratory, successful translation to the clinic has yet to be achieved. Given the individual, medical, and societal burden of TBI, there is an urgent need for alternative approaches to attenuate TBI sequelae and promote recovery. Music based interventions (MBIs) may hold untapped potential for improving neurobehavioral and cognitive recovery after TBI as data in normal, non-TBI, rats show plasticity and augmented cognition. Hence, the aim of this study was to test the hypothesis that providing a MBI to adult rats after TBI would improve cognition, neurobehavior, and histological endpoints. Adult male rats received a moderate-to-severe controlled cortical impact injury (2.8 mm impact at 4 m/s) or sham surgery (n = 10-12 per group) and 24 h later were randomized to classical Music or No Music (i.e., ambient room noise) for 3 h/day from 19:00 to 22:00 h for 30 days (last day of behavior). Motor (beam-walk), cognitive (acquisition of spatial learning and memory), anxiety-like behavior (open field), coping (shock probe defensive burying), as well as histopathology (lesion volume), neuroplasticity (BDNF), and neuroinflammation (Iba1, and CD163) were assessed. The data showed that the MBI improved motor, cognitive, and anxiety-like behavior vs. No Music (p's < 0.05). Music also reduced cortical lesion volume and activated microglia but increased resting microglia and hippocampal BDNF expression. These findings support the hypothesis and provide a compelling impetus for additional preclinical studies utilizing MBIs as a potential efficacious rehabilitative therapy for TBI.

Keywords: Affect; Cognition; Controlled cortical impact; Morris water maze; Music; Recovery; Traumatic brain injury.

Fig. 1.. Experimental paradigm.

Adult male rats were randomly assigned to either a controlled cortical impact injury or Sham surgery. Music (MBI) or No Music (ambient room noise) was initiated 24 h after surgery and provided for 3 h (19:00–22:00) every night for 30 days. Motor (Beam), cognitive (MWM), anxiety-like (OFT), and coping (SPDB) behaviors were assessed during the day on post-surgery days 1–5, 14–20, 29, and 30, respectively. (CCI, controlled cortical impact; MBI, music-based intervention; MWM, Morris water maze; OFT, open field test; SPDB, shock probe defensive burying).

Fig. 2.. Music intervention playlist.

Schematic representation of musical categories that compose the daily playlist. (A) The percentage of musical pieces categorized by composer. Mozart represents the highest percentage (27.78%) of the represented pieces, followed closely by Handel and Corelli with 25% and 16.67%, respectively. (B) The percentage of pieces categorized by musical key, a group of pitches or notes that form the harmonic foundation of a musical piece. (C) Percentage of pieces categorized by the tempo marking which translates to the overall tempo or beats per minute (BPM) that form the speed of a musical piece. The slowest tempo being largo (40–60 BPM) and andante (76–108 BPM) to a medium or walking pace, allegro (120–156 BPM), presto (168–200 BPM) and Prestissimo (200–208 BPM) which are the fastest tempos. (D) The violin plot illustrates the distribution of BPM. The width of the shaded area represents the proportion of pieces of BPM. The median BPM for the music playlist represented by the dashed line is 126.5 BPM with the first and third quartile range of 87.25 and 138.75 BPM.

Fig. 3.. Motor performance.

(A) Time (s) to traverse an elevated narrow beam prior to, and after, TBI or sham injury on post-operative days 1–5. ^#p < 0.05 vs. TBI (No Music) and TBI (Music). *p < 0.05 vs. TBI (No Music). No statistical difference was revealed between the Sham groups exposed to ambient room noise (i.e., No Music) or the music-based intervention (MBI) and thus the data were pooled and are depicted as Sham (No Music / Music). (B) Beam-walk scores prior to, and after, TBI or sham injury on post-operative days 1–5. ^#p < 0.05 vs. TBI (No Music) and TBI (Music). *p < 0.05 vs. TBI (No Music). All data were analyzed by repeated measures ANOVA followed by the Newman-Keuls multiple comparisons post-hoc test. The results are expressed as the mean ± S.E.M. TBI (No Music), n=12; TBI (Music), n=12; pooled Sham (No Music / Music), n=20.

Fig. 4.. Cognitive performance.

(A) Time (s) to locate the submerged (i.e., hidden) platform in the Morris water maze on post-operative days 14–19. ^#p < 0.05 vs. TBI (Music) and TBI (No Music). *p < 0.05 vs. TBI (No Music). No statistical difference (p > 0.05) was revealed between the Sham groups exposed to ambient room noise (i.e., No Music) or the MBI and thus the data were pooled and are depicted as Sham (No Music / Music). (B) Percent of time spent in the target zone (i.e., quadrant where the platform was previously located) following a single probe trial at day 20. ^#p < 0.05 vs. TBI (No Music). *p < 0.05 vs. TBI (No Music). No statistical differences were revealed between the Sham (No Music / Music) and TBI (Music) groups. No differences were noted among the TBI groups in time to the visible platform (p > 0.05), but both required more time than the Sham controls (p < 0.05). Dotted line represents performance at the chance level (25%). (C) and (D) are representative swim paths showing a decrease in navigation to the escape platform on day 19 vs. day 14, as well as differences in the target zone. All data were analyzed by repeated measures ANOVA followed by the Newman-Keuls multiple comparisons post-hoc test. The results are expressed as the mean ± S.E.M. TBI (No Music), n=12; TBI (Music), n=12; pooled Sham (No Music / Music), n=20.

Fig. 5.. Anxiety-like behavior.

Mean (± S.E.M.) time (s) in the center zone of the open field test on post-surgical day 29. ^#p < 0.05 vs. TBI (No Music). *p < 0.05 vs. TBI (No Music). No statistical differences were revealed between the Sham (No Music / Music) and TBI (Music) groups. TBI (No Music), n=12; TBI (Music), n=12; pooled Sham (No Music / Music), n=20.

Fig. 6.. Adaptive vs. maladaptive coping.

(A) Mean (± S.E.M.) number of rears in the shock probe defensive burying test (SPDB). ^#p < 0.05 vs. TBI (No Music). *p < 0.05 vs. TBI (No Music). No statistical difference was revealed between the Sham (No Music / Music) and TBI (Music) groups. (B) Mean (± S.E.M.) burying time (s) in the SPDB test. *p < 0.05 vs. TBI (No Music). No statistical differences were revealed among the Sham (No Music / Music) and the TBI groups, regardless of treatment. (C) Mean (± S.E.M.) immobility (s) in the SPDB test. No differences in immobility were observed among the groups (p > 0.05). TBI (No Music), n=12; TBI (Music), n=12; pooled Sham (No Music / Music), n=20.

Fig. 7.. Histology.

Mean (± S.E.M.) cortical lesion volume (mm³) at day 31 after controlled cortical impact injury. *p < 0.05 vs. TBI (No Music). Inserts in bars depict average size lesions at the level of the dorsal hippocampus. TBI (No Music), n=3; TBI (Music), n=3. No lesion was present in the Sham groups.

Fig. 8.. Immunohistochemistry, Iba1:

Representative photomicrographs (10x) of Iba-1+ cells in the ipsilateral (A, C, E) and contralateral (B, D, F) dentate gyrus (DG) of the hippocampus. Black arrows in the wide field point to activated Iba1+ cells in the DG subfield that are magnified in the inserts. As depicted in Fig. 8G, total percent of resting microglia in the ipsilateral DG was increased in the TBI (Music) group vs. the TBI (No Music) group (p < 0.05), and the Sham (No Music / Music) had significantly more than both TBI groups (p < 0.05). Regarding total percent of activated microglia, the TBI (Music) exhibited less than the TBI (No Music) group, but the Sham control showed less than both TBI groups (p < 0.05). As shown in Fig. 8H, total percent of resting, and activated, microglia in the contralateral DG were increased, and decreased, respectively, in Sham relative to the TBI (No Music) (p < 0.05). The TBI (Music) group did not differ from either TBI (No Music) or Sham (p > 0.05). TBI (No Music), n=3; TBI (Music), n=3; pooled Sham (No Music / Music), n=3.

Fig. 9.. Immunohistochemistry, CD163:

The MBI increased CD163+ cells in the ipsilateral perilesional space after adult CCI injury. (A-F) Representative photomicrographs (10x) of CD163+ cells in the ipsilateral perilesional space of the TBI (No Music) and TBI (Music) groups. (A, B) Representative photomicrograph of CD163+ cells counterstained with Cresyl-violet to better visualize perilesional space in the TBI (No Music) and TBI (Music) groups, respectively. (C, D) Serial sections were DAB stained to observe CD163+ cells in the ipsilateral perilesional space in the TBI (No Music) and TBI (Music) groups, respectively. Black arrows designate CD163+ cells in panels A, B, C, and D. (E, F) Inverted photomicrograph to better visualize CD163+ cells. (G) MBI significantly increased CD163+ cells in the perilesional space compared to the TBI (No Music) group, suggesting increased expression of anti-inflammatory cytokines (p < 0.05). TBI (No Music), n=4; TBI (Music), n= 4. (CCI, controlled cortical impact; CD163, cluster of differentiation 163; MBI, music-based intervention).

Fig. 10.. Western blot, BDNF:

(A) MBI increased BDNF expression in the ipsilateral dorsal hippocampus relative to the TBI (No Music) group at day 31 after CCI injury (p < 0.05). (B) No difference in BDNF expression was observed between the groups in the contralateral dorsal hippocampus (p > 0.05). (C, D) Representative immunoblots of hippocampal BDNF expression. Optical density is normalized to β-actin. TBI (No Music), n=3, and TBI (Music), n=3. (CCI, controlled cortical impact; BDNF, brain derived neurotrophic factor; MBI, music-based intervention).