biology

Posturography

Posturography is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Posturography rather than just read about it. In short: Posturography is the technique used to quantify postural control in upright stance in either static or dynamic conditions. Among them, Computerized dynamic posturography (CDP), also called test of balance (TOB), is a non-invasive specialized clinical assessment technique used to quantify the central nervous system adaptive mechanisms (sensory, motor and central) involved in the control of posture and balance, both i…

Key takeaways

Posturography belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Posturography to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Posturography from memory before moving on to harder problems.

Reference excerpt

Posturography is the technique used to quantify postural control in upright stance in either static or dynamic conditions. Among them, Computerized dynamic posturography (CDP), also called test of balance (TOB), is a non-invasive specialized clinical assessment technique used to quantify the central nervous system adaptive mechanisms (sensory, motor and central) involved in the control of posture and balance, both in normal (such as in physical education and sports training) and abnormal conditions (particularly in the diagnosis of balance disorders and in physical therapy and postural re-education). Due to the complex interactions among sensory, motor, and central processes involved in posture and balance, CDP requires different protocols in order to differentiate among the many defects and impairments which may affect the patient's posture control system. Thus, CDP challenges it by using several combinations of visual and support surface stimuli and parameters. Clinical applications for CDP were first described by L.M. Nashner in 1982, and the first commercially available testing system was developed in 1986, when NeuroCom International, Inc., launched the EquiTest system.

Working Static posturography is carried out by placing the patient in a standing posture on a fixed instrumented platform (forceplate) connected to sensitive detectors (force and movement transducers), which are able to detect the tiny oscillations of the body. Dynamic posturography differentiates from static posturography generally by using a special apparatus with a movable horizontal platform. As the patient makes small movements, they transmit in real time to a computer. The computer is also used to command electric motors which can move the forceplate in the horizontal direction (translation) as well as to incline it (rotations). Thus, the posturography test protocols generate a sequence of standardized motions in the support platform in order to disequilibrate the patient's posture in an orderly and reproducible way. The platform is contained within an enclosure which can also be used to generate apparent visual surround motions. These stimuli are calibrated relative to the patient's height and weight. A special computer software integrates all this and produces detailed graphics and reports which can then be compared with normal ranges.

Components of balance Center of gravity (COG) is an important component of balance and should be assessed when evaluating someone's posture. COG is often measured with COP (Center of pressure) because COG is hard to quantify. According to Lafage et al. (2008) the COG should be located at the midpoint of the base of support if an individual has ideal posture. COP excursion and velocity are indicators of control over COG and are key factors for identifying proper posture and the ability to maintain balance. COP excursion is defined by Collins & De Luca (1992) as the Euclidean*LINK* displacement in the anterior/posterior and medial/lateral directions within the base of support (perimeter around the feet). With poor posture and / or exaggerated spinal curvatures it is possible that the COP excursion would increase which can cause instability as the COP shifts towards the perimeter of the base of support.

Types of tests

The test protocols usually include a Sensory Organization Test (SOT), Limits of Stability Test (LOS), a Motor Control Test (MCT) and an Adaptation Test (ADT). The SOT test was developed by Nashner and is a computerized system that is made up of dual movable force plates and movable visual screen (EquiTest). During the test the patient is instructed to stand still and quietly with eyes open or closed depending on which of the six tests is being administered. The patient performs multiple trials per test; a description of these tests can be found in the table below. The SOT test is based on the fact that there are three sensory systems mainly involved in maintaining balance (vision, vestibular, and proprioceptive). Minute spontaneous body sways are measured as well as reactions provoked by unexpected abrupt movements of the platform and the visual surroundings. Differences in these sways and reactions to system perturbations help to determine the patients ability to effectively use visual, vestibular, and proprioceptive input to maintain posture. Wrisley et al. (2007) found that there are learning effects associated with the SOT test and therefore it could be used clinically to assess, improve and track changes in balance.

SOT results are subdivided in an Equilibrium Score, a Sensory Analysis, a Strategy Analysis and COG Alignment. The sensory analysis calculates 4 different scores: somatosensory (SOM), visual (VIS), vestibular (VEST) and visual preference (PREF) (otherwise known as "visual dependence", an excessive reliance on visual information even when it is inappropriate). The scores are respectively calculated as ratios of the 6 different scores of the equilibrium score:

Somatosensory (SOM) = condition 2 condition 1 {\displaystyle {\text{Somatosensory (SOM)}}={\frac {\text{condition 2}}{\text{condition 1}}}}

Visual (VIS) = condition 4 condition 1 {\displaystyle {\text{Visual (VIS)}}={\frac {\text{condition 4}}{\text{condition 1}}}}

Vestibular (VEST) = condition 5 condition 1 {\displaystyle {\text{Vestibular (VEST)}}={\frac {\text{condition 5}}{\text{condition 1}}}}

Visual Preference (PREF) = conditions 3 + 6 conditions 2 + 5 {\displaystyle {\text{Visual Preference (PREF)}}={\frac {\text{conditions 3 + 6}}{\text{conditions 2 + 5}}}}

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Posturography

Start with the simplest possible case. Write down what Posturography claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Posturography before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Posturography ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Posturography

In research: Posturography appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Posturography in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Posturography is common in secondary-school and first-year university syllabi. It links to neighbouring topics Diagnostic neurology, so understanding it makes those chapters shorter.
In everyday life: Look for Posturography outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Posturography in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Posturography means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Posturography out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Posturography in simple terms?

Why does Posturography matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Posturography?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Posturography.