This week, I, along with so many others throughout the neuroscience and movement disorders community, was deeply saddened by the loss of Dr. Mark Hallett, a pioneer in understanding how the brain controls movement.

He led the Human Motor Control Section at the National Institutes of Health (NIH) for a distinguished career and transformed how we think about both normal and abnormal movement, from the fine coordination of daily motion to complex disorders such as dystonia and functional movement disorders.

His scientific legacy is vast. But beyond his discoveries, Dr. Hallett’s work offers lessons that reach far beyond the laboratory, lessons about awareness, balance, and the art of doing less, better.

1. The Study of Dystonia

Dystonia is a movement disorder characterized by excessive muscle contractions that lead to spasms, cramps, abnormal postures, and sometimes tremor.

Common forms include:

• Cervical dystonia – the neck involuntarily turns or tilts
• Blepharospasm – excessive blinking or involuntary eye closure
• Writer’s cramp – hand and finger spasms during writing

To simplify: when we flex our biceps, the antagonist (opposing muscle, in this case the triceps) should relax. If both are active at once, the result is inefficiency, a tug of war within our own body.

Dr. Hallett’s lab used transcranial magnetic stimulation (TMS) to measure brain activity and found that the inhibitory networks, the neurons that suppress excess activity and maintain smooth coordination, are impaired in dystonia.

He advanced the field by integrating his experiments into a larger thesis: dystonia isn’t just a motor problem but a motor–sensory integration network problem. The sensory system, which constantly monitors movement and provides feedback for fine-tuning, may not be doing its job.

In essence, dystonia reflects a breakdown of internal awareness, the brain’s ability to sense and correct itself.

2. The Study of Functional Movement Disorders

Functional movement disorders (FMD), a very common condition, reported in 3–20% of movement-disorder clinic patients were once called “psychogenic movement disorders”. Neurologist Jean-Martin Charcot studied patients with “hysteria”, a catch-all term for sensory and motor symptoms without clear lesions and his pupil, Sigmund Freud, picked up the thread and proposed that psychological trauma could convert into physical symptoms (“conversion disorder”).

Patients with FMD can exhibit striking, often dramatic, abnormal movements that don’t fit known neurological patterns. Dr. Hallett’s work and that of others following his lead revealed something crucial: these movements arise from voluntary motor pathways, yet the person is unaware of producing them.

In other words, the sense of agency — the awareness that I am the one moving — is lost.

This insight helped destigmatize these conditions and reframed them as disorders of awareness and control, not imagination or malingering.

The Deeper Lessons

Movement seems simple. We decide to lift an arm, and it moves. Yet beneath that simplicity lies a symphony of coordination, timing, and awareness.

We can assume that similar, perhaps even more complex, networks underlie higher cognitive functions on how we think, decide, and act. From that perspective, Dr. Hallett’s discoveries reveal lessons we can apply to life itself.

1. More Effort Is Not Always Better

In dystonia, muscles work against each other. Inhibitory circuits, the brain’s internal “brakes”, malfunction, and more effort (by the muscles) leads to more tension, less fluid motion, and greater fatigue.

I’m reminded of my tennis lessons — the harder I try to hit the ball, the less power it has. My coach keeps shouting, “Relax!” because true swing speed comes only from a loose arm. Of course, nothing makes you tenser than being told to relax!

The same is true for us: when every part of our mind is active, striving, and unwilling to let go, effort can paradoxically lead to worse outcomes.

Efficiency, in movement or in life, needs this balance, sometimes knowing when not to act.

2. Awareness Enables Change

In functional movement disorders, the body moves through voluntary pathways, but the person is unaware of generating the movement. The sense of agency, of ownership, is missing.

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At times, it is challenging to convey this concept to our patients. Yet, we can at least apply this truth to our lives: we can only change what we’re aware of, and perhaps, we have more agency than sometimes we are aware of.

Whether it’s a movement, a habit, or an emotional reaction, awareness creates the space for correction. Without awareness, we repeat patterns automatically, even when they no longer serve us.

Awareness is not a luxury. It is the foundation if we want to change - “Break good”.

3. Balance Requires Feedback

The brain’s feedback loop — sensing what the body is doing and adjusting accordingly — is essential to every motion.

In everyday life, feedback plays the same vital role. When we stop listening to our bodies, to others, to outcomes, we lose the ability to fine-tune.

Awareness without feedback is blind, but feedback without awareness is noise. Learning and growth all depend on this loop: act, sense, adjust, repeat.

4. Science and Humanity Are Not Opposites

Dr. Hallett modeled a rare combination of intellectual rigor and human compassion. He approached even the most complex neurological conditions with curiosity rather than judgment, reminding us that science can illuminate not only how we move, but why we suffer and how we heal.

He challenged the false divide between mind and body, showing that the way we move or fail to move is deeply intertwined with how we perceive ourselves and our world.

A Lasting Legacy

Dr. Hallett’s work reminds us that awareness is not just a state of mind but it’s a skill of the brain. It is how motion becomes graceful, how learning becomes lasting, and how intention becomes reality.

May he rest in peace and may we honor his legacy by moving, thinking, and living with greater awareness.