Sunday, February 28, 2010

Brain rhythm treatment effectiveness: More complex multisensory synchronization may be better?

In IAP Research Report # 9 (Brain rhythm treatment efficacy:  Can we fine-tune our brain clocks), it was concluded (after reviewing 23 studies) that "rhythm-based mental-timing treatments have merit for clinical use and warrant increased clinical use and research attention."  Additionally, it was concluded that:
  • Positive treatment outcomes were reported for four forms of rhythm-based treatment. Positive outcomes were also observed for normal subjects and, more importantly, across a variety of clinical disorders (e.g., aphasia, apraxia, coordination/movement disorders, TBI, CP, Parkinson’s disease, stroke/CVA, Down’s syndrome, ADHD)
  • Most rhythm-based brain-based interventions (the RAS, AOS-RRT and SMT treatment studies) all employed some form of auditory-based metronome to pace or cue the subjects targeted rhythmic behavior.
  • External metronome-based rhythm tools (tapping to a beat, metronome-based rhythmic pacing, rhythmic-cuing via timed pulses/beats) is a central tool to improving temporal processing and mental-timing.
In this context, I was excited to see the recent article by Wing, Doumas & Welchman (2010)--the abstract of the study which I posted this past week.  Wing is the Wing of the Wing-Kristofferson two-level model of rhythm-based synchronization.  Thus, although the current study only focused on n=8 subjects, the research questions, methodology, and quality of research is based on a lengthy program of research and theorizing by Wing and associates.  In this context, I find their findings worthy of this special blog post.  A copy of the article can be viewed by clicking here.

As we all know (from reading this blog), synchronization is a crucial aspect of many forms of skilled human performance.  In many everyday and complex behaviors our CNS is often bombarded by multiple forms of sensory stimuli from which our brain seeks information to fine tune synchronization of time-dependent behaviors.  The current Wing study focused on whether synchronization of behaviors occurs best under a single feedback modality (e.g., auditory cues only) or when the CNS must process similar timing feedback from two sensory modalities concurrently (e.g., auditory and visual; auditory and haptic). 

Common sense suggests that the performance would probably be best when the brain only needs to focus on one form of time-based synchronization feedback (e.g., auditory only).  But...research suggest this is not the case.  The literature reviewed in the article, as well as the specific study reported (looking at synchronization of behavior under single or multiple sensory feedback conditions), favors a cue combination model of synchronization.  Whether auditory+visual synchronization feedback or auditory+haptic feedback, the brain, although tending to favor and weight the importance of one modality over the other (e.g., auditory performance feedback tends to dominate over visual when provided concurrently), appears to benefit from having more than one form of feedback.  Apparently the CNS combines feedback from different senses in a differential weighting algorithm (i.e., pays attention to one form of feedback more and gives it more weight in adjusting performance) which increases the precision of synchronization of behaviors.

Although replication is needed, this study suggests that rhythm-based mental timing or synchronization treatments (e.g., Interactive Metronome;  see conflict of interest notice) may be most effective when multisensory feedback is provided to subjects...and not just a single form of feedback.  Of course, there will always be individual differences and some individuals may benefit more from a single form of feedback (e.g., auditory beeps only).  Research that would identify individuals who do not benefit from the advantages of multisensory feedback would be of interest.  My only criticism of this study is the failure of the authors to hypothesize what occurs at the neurological level when multisensory cue feedback is provided---i.e., why does it improve performance?

For appears that "more is better."

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