Infra-Slow Fluctuation Neurofeedback – a novel experience

Infra-Slow Fluctuation Neurofeedback – a novel experience

I just completed 3 days learning and experiencing ISF (infra-slow fluctuation) neurofeedback, in a workshop presented by Mark Smith.  Both the learning experience and the neurofeedback process were eye-opening, to say the least.  The theory has to do with cortical activation, shifts in parasympathetic response, and achievement of a new mental state.  What I found is that, by listening to a simple tone that told me when my “infra-slow” brainwaves shifted one way or another, I could be led into these states effortlessly.

ISF is not only operant conditioning, it is pre-operant conditioning.  In “traditional” neurofeedback, information is presented to the brain with the expectation that the brain will discern the difference between states (generally “reward” and “no reward”), and thus learn to self-regulate.  However, this approach assumes that the brain is ready to learn, and is interested in learning.  I am not referring to the individual thinking he or she is interested in learning.  I am referring to the fundamental ability of the brain to respond to stimuli in a manner that facilitates self-control.  In many cases, the brain is not ready, or even interested, at a fundamental level, in learning.  We call such situations being “stuck.”

Stuck patterns can involve power, power distributions, connectivity, or other aspects of EEG properties.  There is a common underlying mechanism to the control of variability and modulation, and this mechanism involves not only neurons, but also glia, other supportive tissues, and the entire body.

The initial experience, with settings of 0.0001 to 0.0030 Hz, was relaxing, yet alert.  The tone replaced a mantra, so that a meditative state could be achieved with external focus on the sound.  The cadence of the feedback sound became familiar, and its effects were positive.  When the frequency band was changed to 0.0001 to 0.0035, a very different experience ensued.  Within 30 seconds, I was aware that this was not the same cadence, or familiar pattern that I had just experienced and appreciated.  After less than 2 minutes, my left thigh began to twitch once, then twice, then again.  I decided this was enough of .0035 for me.  I had my partner switch back to the 0.0030 setting and restart.  Again, within 30 seconds, a profound change was apparent, and I once again experienced the familiar and reassuring cadence that I had come to recognize.

Neurofeedback at infra-slow frequencies does not mean that a cycle occurs with a very long period, as has been suggested.  This criticism is based on ignorance of the fundamental signal dynamics and principles, combined with never having seen the practice in action.  In reality, these filter settings serve to block out all of the cyclic activity above a certain range, but still pass the minute fluctuations that arise due to the slowest regulatory processes.  During feedback training, a sound is heard that is either lower (signal going down) or higher (signal going up), as the ISF slgnal fluctuates ever so slightly.  Changes as small as 0.01 microvolt can be seen, and the fluctuations are continuous.  A signal may change 1, 2, or even more times per second, or it may hold on for just a few seconds.  If it does not change at all, then the brain is “stuck” and little flexibility is possible.

In order to optimally control, or self-regulate, this signal, my experience was that when the fluctuations got as small as possible, in my case as low as 0.05 microvolts in shift, or smaller, then the modulation was maximally responsive.  By keeping brain activity poised on a knife-edge between states of activation, it experiences what it is to be in control, and to achieve balance.  What seems to come with this is a sense of harmony, peace, and as one participant put it, “feeling like I’m the person I’m supposed to be.”

Individual responses are finely tuned to the ISF frequency bands used.  Increase the frequency and there will be more activation, agitation, or as I experienced, even a bodily sense of unrest and some motor activation.  Lower the frequency, and reduced, even depressed, states can be fostered.  This is what gives ISF its power in a practical setting, and makes it important that practitioners do not simply follow a “plug and go” approach, but remain close to their clients.

ISF appears to be an ideal entry point for mental health professionals who are truly interested in their clients, and are used to working with client reactions, individual differences, and idiosyncrasies.

Mark has an excellent article online at:


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