Working memory and mental timing

I've previously attempted to summarize the gist of the conclusions of Dr. Penny Lewis (see "Mental timing scholars" section of the IQ Brain Clock) on the important association between mental/interval time-keeping and working memory. In addition, I recently posted a series of PowerPoint slides (see "On-line PPT slides" section of the IQ Brain Clock) where, if you take time to view the entire show, you will see that I've hypothesized that working memory (and other related neuropsychological constructs of executive function; controlled executive attention) most likely plays a prominent role in performance on SMT (synchronized metronome tapping) performance tasks, and, may be a causative factor in explaining the benefits of SMT-based training (e.g., Interactive Metronome).

Below are a few snipets from Dr. Lewis important paper ("Remembering the time: A continuous clock - a viewable copy is under the "Key research articles" section of this blog) that links working memory and the brain's master internal clock.

• Behavioural evidence that working memory and time measurement draw upon the same cognitive resources stems from dual-task studies showing interference between these two types of processing. Both visuospatialand phonological working memory tasks disrupt timing, and the extent of such disruption has been shown to correlate with the extent of working memory load (e.g. number of items to be remembered, number of syllables to be rehearsed or degrees of mental rotation).

• Turning to pharmacology, manipulations targeting working memory can also disrupt cognitive timing.

• Additional evidence linking time perception to working memory stems from the observation that both are modulated by dopamine, a neurotransmitter which regulates activity throughout much of the brain, including the prefrontal cortex. The influence of prefrontal dopaminergic projections upon working memory is well documented

• Because the basal ganglia are heavily innervated by dopamine, and because their function is severely disrupted in Parkinson’s disease, the influence of dopamine on subjective time measurement has typically been interpreted as support for the central role of these structures in timing.

• Overall, the data on dopamine suggest a selective influence of prefrontal dopamine on more cognitive timing tasks, thus implying that this form of timing might be mediated via the same dopamine-sensitive processors as working memory.

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