Ted Carrick

Toronto to Cape Canaveral

Ted Carrick has held since 1979 that a neuron pool can fire poorly with nothing to see on a scan

Carrick calls the underperforming state a physiological lesion, and holds it distinct from an ablative lesion, where tissue is destroyed and gone. Groups of neurons can perform badly while every image reads normal, and the right input changes how readily they fire. He has held that position since 1979. The whole examination and every therapy in functional neurology follow from that one distinction.

Carrick's degree and his Institute arrive in the same year

Carrick was born in Toronto, Ontario on February 26, 1952. His father was a career soldier in the Princess Patricia's Canadian Light Infantry, and the family moved through Calgary, Edmonton and Winnipeg. He earned his Doctor of Chiropractic from Canadian Memorial Chiropractic College in 1979 and founded the Carrick Institute the same year, teaching its first course in Epsom, New Hampshire. His first indexed paper followed four years later.

The doctorate that shaped the examination

Carrick completed a PhD in education at Walden University in 1996, and the dissertation title explains the discipline better than any later description of it. It is called Neurophysiological Implications in Learning. Carrick has said he pursued the doctorate because his patients had to learn to walk, speak and use their arms again. He later added a Master of Science in Health Professions Education from the MGH Institute of Health Professions in Boston.

Where Carrick works now

Carrick lists five affiliations on his 2026 papers. Three sit in the United States: the Department of Neurology at the Carrick Institute in Cape Canaveral, Florida, the University of Central Florida, and the MGH Institute of Health Professions in Boston. At Central Florida he lists both the College of Medicine and the Burnett School of Biomedical Sciences. The fifth is the Centre for Mental Health Research in association with the University of Cambridge. He is a full professor of neurology at Central Florida and a senior research fellow at the Cambridge-associated centre. He also carries professorial titles in neurology at Parker University in Dallas, Logan University in Missouri, and Life University in Marietta, Georgia.

The physiological lesion

Functional neurology treats a firing problem as a lesion in its own right

Carrick's discipline rests on the central integrative state: the running sum of every excitatory and inhibitory influence arriving at a neuron pool at a given moment. That sum sets the baseline from which the pool answers the next signal. A 2017 scoping review in Chiropractic and Manual Therapies recorded the version functional neurology teaches. Three parameters set the state: the pool's oxygen supply, its nutritional supply, and the synaptic stimulation reaching it.

A normal scan is where the functional neurology examination begins

Carrick's position is that a patient can carry dizziness, unsteadiness, blurred pursuit, slowed cognition or a movement that no longer sequences while every image reads normal. The field calls that reversible change in firing a physiological lesion, and holds it reversible because the nervous system is plastic. An ablative lesion is a different object, because the tissue is destroyed. Functional neurology hunts the first and expects imaging to stay silent about it.

Hemisphericity extends the claim to a whole hemisphere

Carrick scaled the construct upward, and this part is his. Hemisphericity names a cerebral hemisphere carrying a dysfunctional central integrative state, and the field holds that such a hemisphere can express itself in cognitive, motor, immune and autonomic terms at once. That is why a functional neurology examination checks the pupil, the gait and the digit span in the same visit. The construct holds that all three read one state.

Carrick's examination grades how well a pathway performs today

A conventional neurological examination asks whether a pathway is intact or destroyed, and answers yes or no. Carrick's examination asks how well the pathway is working today and what would change it inside the visit. Degree needs measurement, so the examination runs on instruments that produce numbers. The vestibular nuclei, cerebellar peduncles and brainstem pathways those instruments interrogate are mapped in the nervous system curriculum.

Carrick's examination

Carrick's examination locates the failing loop and names its side

A functional neurology visit runs dozens of small tests across five components before anyone treats anything. The Carrick Institute's clinical neuroscience module names them: mental state, motor system, sensory system, cranial nerves, and cerebellar system. The scoring is conventional, with muscle power run 0 to 5 and reflexes 0 to 4. The clinician reads the pattern across the whole set, because the target is a firing state that no single test reports.

Eye movements are read as a live readout of brainstem and cerebellum

Eye movement testing carries more weight here than in most examinations, because the oculomotor system is fast, quantifiable and wired through the structures the discipline is trying to reach. The saccade test taught in the curriculum is specified to the centimeter. The examiner holds both thumbs at eye level about 50 cm from the patient, spaced to require 30 degrees of lateral eye movement. The patient fixes on the bridge of the examiner's nose and jumps to whichever thumb moves. Overshoot and undershoot are the findings.

The blind spot and the pupil

Two tests sit further from routine practice. Carrick's curriculum teaches clinicians to map the physiologic blind spot, the small area of each visual field with no photoreceptors, and holds that its size and shape report on the cortex above it. The pupil reports sympathetic and parasympathetic balance directly, sitting between dilation of the iris and constriction driven through the Edinger-Westphal nucleus. That outflow runs on through the baroreflex to the orthostatic tests, and it is traced in full on the autonomic nervous system page.

Balance, gait, and the instruments borrowed from concussion practice

Balance and gait are measured because they integrate everything upstream of them. Posturography records sway on firm and unstable surfaces. Clinicians also use instruments standardized elsewhere, including the King-Devick rapid number naming test, the Sport Concussion Assessment Tool, and the Balance Error Scoring System. Digit span is run forward and backward. Carrick has described the examination as generating objective numbers a clinician can track over time, which is the reason for scored instruments.

Dosed input

Treatment stimulates the failing loop or inhibits its antagonist

The Carrick Institute's neurorehabilitation module sorts 14 therapy categories by target. Seven of them are vestibular rehabilitation, saccadic work, pursuit work, visual motion sensitivity, self motion sensitivity, canalith repositioning for benign paroxysmal positional vertigo, and light therapy. The others cover frontal and parietal work, laterality training, and the treatment of phorias and convergence deficiency. Each therapy targets the loop the examination named. The full method is set out on the Functional Neurology page, which covers the selection rules in detail.

The inputs are specific and small

A patient repeats one small movement for minutes at a time. Gaze stabilization has the patient fix on a target and turn the head, or run a 2x viewing exercise in which target and head move oppositely to double retinal slip. Optokinetic stimulation presents a moving field, set deliberately opposite the direction that provokes the patient's motion sensitivity. Laterality training has the patient judge images of left and right body parts under time pressure, against a reference of better than 80 percent accuracy at 1.5 to 2.0 seconds. Flashing lenses load one visual hemifield on a 10 second cycle of 2 seconds flashing and 8 seconds rest.

Every input stops on a visible sign

Each input in the discipline has a direction, an amplitude, a duration and a stopping rule, and the stopping rule is something the clinician can see. In the light therapy protocol the signal to stop is pupil dilation, read as fatigue of the system being loaded. In vestibular rehabilitation the instruction is that an exercise should provoke mild symptoms at worst. The stimulus is titrated to what a particular nervous system can integrate today, then advanced as it integrates more.

The retest decides whether the input landed

Carrick built the discipline so the answer arrives inside the visit. The examination produces a number, the input is delivered, and the same measurement is taken again. A saccade that overshot by a measurable margin either overshoots less or it does not. Sway changes or it does not. That cycle of measure, input, measure is the discipline's operating loop, and the Unified Model of Tone borrows it without alteration.

The blind spot study

Carrick's 1997 study measured a cortical map before and after a C2 adjustment in 500 subjects

The study ran in the Journal of Manipulative and Physiological Therapeutics in October 1997, at volume 20, issue 8, pages 529 to 545. It is the paper functional neurology is best known for. Carrick divided adult volunteers into six comparative groups and gave each a specific manipulation of the second cervical motion segment. Blinded examiners mapped the cortical hemispheric blind spot before and after. Twelve null hypotheses were stated in advance. The critical alpha was 0.004.

The result reverses with the side of the input

Manipulation on the side of an enlarged cortical map was associated with increased contralateral cortical activity, at p less than 0.001. Manipulation on the side opposite an enlarged map was associated with decreased cortical activity, at the same significance. The change appeared in one cortical hemisphere and not both. A result that reverses with the side of the input is a result about direction, and direction is the variable the whole discipline manipulates.

The design puts the measurement above the reported symptom

Carrick chose a cortical measure over a symptom questionnaire, in 1997, with 500 subjects and blinded examiners. That choice sets the pattern for everything he has published since. His papers pick an instrument that produces a number, take the number before and after, and report the difference. Klotzek and colleagues repeated the shape of the design in Brain Sciences in March 2024, quantifying horizontal saccades before and immediately after cervical manipulation in one male patient with post-concussion syndrome.

The indexed record starts in 1983

Carrick's first indexed paper appeared in the same journal in September 1983, at volume 6, issue 3, pages 129 to 137. It examined lateral flexion anteroposterior radiographs in patients with cervical radiculopathy and found that deviations from the normal coupling mechanism tracked the clinical level. Reduction of the aberrant coupling by manipulation was followed by improvements in sensation, motor power and deep tendon reflexes. That paper is a mechanical argument, and the 1997 paper moves the same argument into the cortex.

The papers

Carrick's indexed record runs from 1983 to 2026

Marine Demortier and Charlotte Leboeuf-Yde cataloged the output in Chiropractic and Manual Therapies in 2020. Their October 2018 search of PubMed, Scopus and ResearchGate found 121 documents by F.R. Carrick, of which 39 were full-text scientific research articles. He is listed as an author on papers published in 2026, so the record is still growing.

Balance and posturography

Carrick, Oggero and Pagnacco ran a music listening protocol on 266 subjects with no history of falls or vertigo, measuring computerized dynamic posturography before and after. It appeared in the Journal of Alternative and Complementary Medicine in June 2007. Seventy-three percent of that group carried balance abnormalities associated with an increased probability of falling. A companion paper in Disability and Rehabilitation the same year compared elite gymnasts with non-gymnasts and related posturographic scores to the ability to learn a new routine.

The pupillary light reflex separates concussed from non-concussed subjects

Carrick's group has published a series of concussion measurements. In Life in October 2021 the pupillary light reflex differed by concussion history on five variables: latency, maximum diameter, minimum diameter, constriction velocity, and 75 percent recovery time. In Brain Sciences in December 2020, head position off the neutral plane lowered posturographic stability scores in post-concussion subjects and left healthy controls unchanged. A 2021 paper in Frontiers in Neuroscience compared brain vital signs in 58 elite youth ice hockey players against a general reference set of 135. The concussion page traces the physiology those markers are reading.

Carrick's randomized trials in stroke, autism, and curriculum design

Thirty-four patients with acute middle cerebral artery ischemic stroke were randomized to aspirin alone or to aspirin plus subject-specific eye-movement training. Quantitative EEG and the NIH Stroke Scale were the outcomes, published in Frontiers in Neurology in 2016. Eighty-three children with autism spectrum disorder were randomized to an active or sham auditory neurofeedback device for 12 weeks, reported in the same journal in 2018, with 34 completing. A third trial in 2017 randomized 274 subjects between a traditional classroom and an online flipped classroom for a 25-hour neuro-otology curriculum.

Combat veterans and post-traumatic stress

Carrick's largest clinical population is military. Frontiers in Public Health published a study of 98 combat veterans who had suffered traumatic brain injuries in 2015. It measured the Clinician Administered DSM-IV PTSD Scale before and after a brain and vestibular rehabilitation program. Before treatment, 75 of the 98 subjects sat in the two most severe categories. A companion paper followed 26 subjects at one week and three months, registered as ClinicalTrials.gov NCT02003352, and reported the reduction holding at both points.

Head-eye vestibular motion in chronic post-concussion patients

Carrick, Clark, Pagnacco and Antonucci reported a retrospective review in Frontiers in Neurology in 2017. Every subject had been disabled from work or school for more than six months after a sports concussion, and all of them completed a five-day head-eye vestibular motion program. Outcomes came from the seven modules of the C3 Logix concussion management system, taken before and after. Symptom severity fell and standardized assessment of concussion scores rose.

The DACNB

The credential Carrick's field runs on has to be earned again every year

The Diplomate of the American Chiropractic Neurology Board takes an active license and 300 hours of postdoctoral neurology education. Candidates then pass a written examination and a practical examination. The program itself must be approved through the Commission for the Accreditation of Graduate Education in Neurology. A licensed clinician adds the specialty on top of an existing practice. Carrick's stated position is that board certification comes from an independent agency and has to be earned again every year.

The DACNB expires annually

Diplomates recertify every year. The hour requirement runs on a rolling window: at least 60 hours of accredited continuing education across two continuous calendar years, with a minimum of 15 hours in any one year. A clinician who falls short of the hours stops holding the diplomate.

National accreditation in 2003, and how small the specialty was

Dynamic Chiropractic reported in October 2003 that the American Chiropractic Neurology Board's diplomate program had received full accreditation from the National Commission for Certifying Agencies, running through August 31, 2008. The report calls it the first time a chiropractic credentialing agency received full NCCA accreditation. It also gives the scale of the specialty at that moment: fewer than 260 active certified chiropractic neurologists, against more than 73,000 practicing chiropractors worldwide.

Fellowships sit above the diplomate

Credentialing in the field now runs on more than one track. FACFN denotes a Fellow of the American College of Functional Neurology. The International Association of Functional Neurology and Rehabilitation, formed in 2010, opened its own board examination to several licensed professions. Carrick holds the DACNB alongside diplomate and fellowship designations from other neurology boards.

The Carrick Institute

The Carrick Institute built the first chiropractic neurology curriculum in 1985

The Carrick Institute's own history dates the first full chiropractic neurology curriculum in the world to 1985, six years after its first course in Epsom, New Hampshire. The Institute reports expansion across North America, Europe and the Pacific Rim in 1991, faculty above 50 and more than 100 courses by 2005, and 100 instructors and 200 courses by 2015. Carrick built the curriculum that made the field teachable by people other than himself.

From one course to more than 325

The Institute now runs from Cape Canaveral, Florida. It reports more than 325 courses, more than 18,000 licensed clinicians using its material, and a presence in 13 countries. It launched the International Symposium on Clinical Neuroscience in 2015 and awarded its first Master of Science degrees in Clinical Neuroscience in 2022, alongside an interdisciplinary concussion program.

The standard text

Functional Neurology for Practitioners of Manual Therapy was written by Randy W. Beck and published by Churchill Livingstone in 2008, with a foreword by Carrick. It carries the theory from embryology through receptor physiology to the functional systems of the brain.

The PBS broadcast

The PBS series Body and Soul with Gail Harris built an episode around Carrick, titled Waking Up the Brain: Amazing Adjustments. The page for that episode records a specialty practice in the diagnosis and treatment of neurological disorders running twenty-one years at the time of the broadcast.

Loops and retests

Carrick's central integrative state is tone read at the scale of a neuron pool

Functional neurology and the Unified Model of Tone use the same three words for the same construct, and neither took them from the other. Carrick built up from the single neuron. The model built down from the whole organism. They met in the middle, at a summed input that decides how readily a pool of neurons fires.

The construct holds across scales

The model states the identification directly. The central integrative state is tone read at the scale of a single cell, and tone is that same state read at the scale of a whole organism. The construct holds across scales. Only the instrument changes. Carrick supplied the bedside version, with a 300-hour postdoctoral curriculum built around it.

A loop that fires poorly is a distortion of tone

The physiological lesion and the model's account of the subluxation describe one event in two vocabularies. Carrick names a pool of neurons whose firing threshold has drifted while the tissue stays intact. The model names a region whose tone no longer updates against what the rest of the body reports, a dynamical lesion rather than a structural one. Nothing an image measures needs to be abnormal in either account, because what has failed is a relationship.

The retest is the model's discipline too

An input meeting a particular tone creates an outcome, so the same drill moves one patient and does nothing for the next. That makes the second measurement the only reliable report on what happened. A functional neurology visit ends with the test that opened it, and the model asks the same of every intervention in the library.

Input quality is the variable the therapies work on

The nervous system continuously reweights proprioceptive, vestibular and visual input according to how reliable each channel is. Degraded signaling gets discounted, and the system leans harder on the channels it still trusts, a strategy that costs more and fails sooner. Functional neurology manipulates that weighting on purpose. An optokinetic drill run against the direction of a patient's motion sensitivity changes how much the system trusts vision. That is an intervention on input quality, which is a foundation of tone.

Carrick's discipline uses many doorways at once

The model holds that specificity is correspondence between the structure of an input and the pattern the body is holding, rather than force or anatomical accuracy alone. It also holds that no single access point is the lynchpin. Most techniques use one doorway. Carrick's discipline uses the eyes, the vestibular apparatus, the skin, the joints, light, sound and the spinal adjustment, and selects among them from the examination. George Goodheart reached a related position from a different instrument, reading a muscle response while an input was applied.

What the model predicts

Two predictions follow, and both belong to the model. The measures a Carrick examination collects should covary. Blind spot area, saccadic accuracy, sway, pupil response and autonomic reactivity should shift in a shared direction after a matched input, because the model holds they read one variable, with compensation deciding which readings carry the change. Moving together after that input is what establishes the unification claim. Second, a matched input should move a cohort that starts over-facilitated and a cohort that starts under-facilitated toward the same middle, narrowing the spread rather than shifting everyone one way. Both tests run on instruments the discipline already owns, and both bear on how the nervous system builds its model of the body.