Blog: The Predictive Brain State

Our brains have an inherent challenge. It takes time to process incoming information and the outside world is constantly changing. How can we be in the present? By the time we catch up to the present, it has already passed.

So our brains are always in the past. Yet we interact in the present – we catch the ball, we have conversations, and we drive our cars. How can we interact if all we sense has already happened?

The only way to solve this dilemma is to be in the future. We have to anticipate or predict the incoming sensory information in order to interact.

We predict the future to interact in the present and sense the past.

This important predictive brain function is revealed in numbers. There are 87 billion neurons in the brain and 80% of them are the granule cells found in the cerebellum. The input to the cerebellum is from sensory areas of the brain and the output is to motor and cognitive areas.

The cerebellum synchronizes incoming sensory information with motor and cognitive function by prediction.

This cognitive connection has only been revealed recently showing that over 50% of the cerebellum output is to cognitive or attention areas of the brain. The cerebellum learns to predict correctly by repetition, eventually synchronizing sensory input to cognitive and motor processing.

 Think about when you feel tired or have jet lag, do you feel “off”, “out of sync”? You can’t keep up as well with what is going on around you. It is hard to pay attention because you can’t predict well. Your brain needs sleep to retune the cerebellar cells to regain your ability to synchronize.

Prediction can be defined as anticipation, but it is really incomplete without accurate timing. Synchronization is a better term since it implies [same] timing – synchronizing sensory input with motor or cognitive output.

[Prediction x timing] = synchronization = attention

In order to pay attention, we must predict incoming sensory information in time and space to interact.  Attention has a lot of different meanings – selective, sustained, or distracted. Attention combines spatial and temporal prediction using synchronization to achieve (selective), maintain (sustain-concentration) sensory focus, and not get distracted.

Attention is our window to the world. It allows us to interact with the outside world. Without attention we are in a past driven by the outside world, not a future driven by ourselves.

While attention is our window to the world, our eyes are the window to the brain. It doesn’t make a difference if you can’t measure a difference- how can we measure prediction, synchronization, or attention? The eyes are the perfect system to measure sensory-motor synchronization since they sense visual input and must move to have visual input land on the fovea of the eyes. Using EYE-SYNC, we are now finally able to objectively measure sensory-motor synchronization in order to measure attention.

Vision takes up the majority of brain space compared to other sensory modalities and the brain moves the eyes. Visual attention is a necessary continuous function for us. What differentiates us, higher primates, from other species is the fovea and smooth pursuit eye movements.

If you hold out your hand and look at your thumb, that is all you can focus on or foveate, with the rest of the visual field a blur. Now move your thumb back and forth and follow it – that is smooth pursuit eye movement. Since we can only foveate a very small portion of the outside world and it moves, we must have very precise smooth pursuit eye movements to accurately see – this is called dynamic visual synchronization.

How can we measure dynamic visual synchronization? We need to have a predictable target stimulus and measure the eye position with respect to the target over time.

The key metric is the difference in eye position, with respect to the target position over time – this is variance or jitter.

Motor and cognitive variances or jitter are indicators of neurological impairment and pathology and are reflected in the neurological exam – eye movements, coordination using finger pointing, gait, and balance. These exams however are qualitative and variance is not measured.

The eye-target variance analytics (EYE-SYNC) for the first time give us a quantitative tool to quickly, accurately, and reliably measure variance in the visual and vestibular ocular-motor system. The EYE-SYNC metrics can be used to evaluate dynamic visual synchronization in all conditions of movement:

  • Self is moving with respect to outside world and focus on outside world: Vestibular Ocular Reflex (VOR).
  • Self is moving with respect to outside world and focus on self: Vestibular Ocular Reflex cancellation (VORx).
  • Outside world moving with respect to self: smooth pursuit, saccades, and convergence.

The target stimulus test for each is just 15 seconds sometimes repeated twice with an automatic immediate report that shows accuracy of spatial and temporal prediction using variance metrics (www.syncthink.com).

For the first time we have quantitative measures of an individual’s dynamic visual synchronization to the outside world or how well one pays attention. Through our research we now know that attention varies by age, fatigue, and cognitive impairments (www.braintrauma.org). We knew that attention varies from past research using neuro-cognitive testing, which is lengthy, has learning and effort confounders, but dynamic vision synchronization metrics have not been applied to attention assessment in a comprehensive manner.

Now that we have robust metrics that can be quickly calculated and displayed, we have the opportunity to improve attention. Instant feedback of the subject’s eye position variance allows brain feedback to correct errors and thereby improve performance – a known cerebellar function.

At baseline we are finding 5-10% of varsity athletes have difficulty with temporal prediction in certain spatial quadrants, which can make them susceptible to injuries. Most of these impairments are in the lower dynamic visual field, so kicking a ball or typing on a keyboard would require the person to bend their neck to get the lower visual field into the upper field for adequate dynamic visual attention. Some have left or right quadrant impairments but not the upper quadrant, which seems to be robust in normal individuals.

Training eye and body movements simultaneously using dynamic synchronization metrics in real world movements including sports will dramatically accelerate brain performance.

Predictive Brain State science will enable us to better classify neurological and cognitive disorders and target treatments. It also will improve baseline brain performance to prevent injuries and boost athletic and academic performance.