This is an OBG (oldie-but-goodie) post I originally made on the
IM-HOME blogTime and space are the two fundamental dimensions of our lives. All
forms of human behavior require us to process and understand information
we receive from our environment in either spatial or temporal patterns.
Even though mental timing (temporal processing) research is in a stage
of infancy (when compared to spatial processing) important insights
regarding the human
brain clock have emerged.
Below is a list (albeit incomplete) of some of the major conclusions
regarding the human brain clock. The sources for these statements come
from my review of the temporal processing and brain clock literature
during the past five years. Most of this information has been
disseminated at the Brain Clock blog or the
Brain Clock Evolving Web of Knowledge (EWOK).
The goal of this post is to provide a Readers Digest summary of the
major conclusions. This material can serve as a set of "talking points"
at your next social event where you can impress your friends and family
as you explain why you use the high-tech IM "clapper" (with a cowbell
tone no less) either as a provider or as client.
Our brains measure time constantly. It's hard to find any complex human
behavior where mental timing is not involved. Timing is required to
walk, talk, perform complex movements and coordinate information flow
across the brain for complex human thought. Think about moving your arm
and hand to grasp a coffee cup. The messages to perform this task
originate in your brain, which is not directly connected to your arm,
hands and fingers. The ability to perform the necessary motor movements
is possible only because the mind and extremities are connected via
timing. Precisely timed neural messages connect your brain and
extremities. You are a time machine.
Humans are remarkably proficient at internally perceiving and
monitoring time to produce precisely timed behaviors and thinking. “We
are aware of how long we have been doing a particular thing, how long it
has been since we last slept, and how long it will be until lunch or
dinner. We are ready, at any moment, to make complex movements requiring
muscle coordination with microsecond accuracy, or to decode temporally
complex auditory signals in the form of speech or music. Our timing
abilities are impressive…” (Lewis & Walsh, 2005, p. 389).
To deal with time, humans have developed multiple timing systems that
are active over more than 10 orders of magnitude with various degrees of
precision (see figure below from Buhusi & Meck, 2005). These
different timing systems can be classified into three general classes
(viz., circadian, interval, and millisecond timing), each associated
with different behaviors and brain structures and mechanisms. The
fastest timing system (millisecond or interval timing) is involved in a
numerous human behaviors such as speech and language, music perception
and production, coordinated motor behaviors, attention, and thinking.
This fast interval timing system is the most important timing system for
understanding and diagnosing clinical disorders and for developing and
evaluating effective treatment interventions for educational and
rehabilitation settings. It is this timing system, and the relevant
research, that is relevant to understanding
Interactive Metronome. (Note. See my conflict of interest statement at this blog. I have an ongoing consulting relationship with IM).
Although there is consensus that the human brain contains some kind of
clock, the jury is still out on the exact brain mechanisms and
locations. It is also not clear whether there is one functional master
clock or a series of clocks deployed in different brain areas. The areas
of the brain most consistently associated with milli-second interval
mental timing are the cerebellum, anterior cingulate, basal ganglia, the
dorsolateral prefrontal cortex, right parietal cortex, motor cortex,
and the frontal-striatal loop. That is a mouthful of technical brain
terms. But, if you can memorize them and have them roll of your tongue
with ease you will “shock and awe” your family and friends. Most of
these areas of the brain are illustrated below. Now, if you really want
to demonstrate your expertise, get your own illustrated
“brain-in-a-pocket”. These images were generated by the free
3D Brain app
available for your iPhone or iPad. Even cooler is the fact that you can
rotate the images with your finger! You can give neuroanatomy lessons
anytime…anywhere!
Research suggests that mental interval timing is controlled by
two sub-systems.
The automatic timing system processes discrete-event (discontinuous)
timing in milliseconds. The cognitively-controlled timing system deals
with continuous-event timing (in seconds) that requires controlled
attention and working memory. Both systems are likely involved in IM.
For example, the synchronized clapping requires motor planning and
execution, functions most associated with the automatic timing system.
However, the cognitive aspects of IM (focus, controlled attention,
executive functions) invoke the cognitively controlled timing system.
Aren’t these brain images awesome?
The dominant model in the brain clock research literature is that of a
centralized internal clock that functions as per the
pacemaker–accumulator model. Briefly, this is a model where an
oscillator beating at a fixed frequency generates tics that are detected
by a counter. For now I am just going to tease you with an image of
this model. You can read more about this model at the
Brain Clock blog.
Research suggests that the brain mechanisms underlying mental timing can be
fine-tuned (modified) via experience and environmental manipulation. Modifiability of mental interval timing and subsequent transfer suggest a
domain-general timing mechanism
that, if harnessed via appropriately designed timing-based
interventions, may improve human performance in a number of important
cognitive and motor domains.
