Sensory/ Motor Responses to Movement

Sensory perception from perspective videos may produce dizziness, nausea, or discomfort for individuals. This sensation arises from difficulties in coordinating eye movements with head movements, which is referred to as optical righting .

The labyrinthine righting reflex is associated with the inner ear, which plays a crucial role in balance and equilibrium. This reflex is activated by changes in body position in relation to gravity. It is similar to the tonic labyrinthine reflex (TLR).
The response involved in the labyrinthian reaction is that the head moves in the opposite direction of body movement to maintain vertical alignment.

Example: When sitting at a desk, moving shoulders to one side causes the head to move to the opposite side to remain upright. If moving forward, the head extends while the trunk flexes, and vice versa when moving backward.

The tonic labyrinthian reflex in contrast results in body flexion when the head is tipped forward, indicating that the tonic reflex and labyrinthine reflex are somewhat opposed despite their interrelation in governing movements.

The labyrinthine and optical righting reflexes persist throughout life and lead to the development of neck righting and trunk righting responses.
The neck immature response is integrated by the age of 4-6 months, while the neck mature response is integrated by the age of 5 years.

The neck righting reflex utilizes proprioceptive and kinesthetic awareness from stretch receptors in the neck. When the head moves, the body aligns itself to keep everything organized.
An immature response is characterized as a log roll or block roll, where the body rotates as one unit.
A mature response involves segmental rotation, where the head rotates independently from the spine, allowing for more refined control over movement.

In observing a child, turning the head leads to the entire body rolling over as an immature response, as compared to a mature response, where the shoulders lead the movement followed by the pelvis.

Similar to neck righting , the trunk righting reactions demonstrate the same age of onset and integration timelines. Immature trunk righting reflects a log roll, while mature trunk righting results in segmental rolling.
Movement in immature trunk righting occurs when the lower body moves first, contrasting with head righting where the head initiates movement.

Integration of trunk and head righting occurs when a child can transition successfully from a supine to a standing position, indicating that equilibrium reactions have developed further.

Protective reactions, also referred to as parachute reactions, develop in response to high-velocity displacements of the body. These reactions persist throughout life to ensure safety during locomotion.
Leg extension is demonstrated in a downward displacement when a child feels as if they are dropping. This response illustrates an instinct to catch oneself by extending the legs.

Forward Upper Extremity Reaction: When infants begin sitting, they typically lean forward and extend their arms to prevent falls.
Sideways Parachute Reaction: As infants gain trunk strength and upright posture, they will extend arms sideways for balance.
Backward Reaction: As upper trunk extensors strengthen, an infant will reflexively extend their arms backward to catch themselves during backward falls.
Stepping Reaction: When standing, a child will step to regain balance after losing it, marking the last protective reaction to develop.

Equilibrium reactions emerge slightly later than righting reactions and involve extremity movements. Unlike righting reactions that primarily engage the head and trunk, equilibrium reactions also incorporate limb adjustments.

The aim of equilibrium reactions is to optimize the base of support in response to body position changes, to maintain the center of mass above the base of support.
Examples include shifting the trunk or extremities in response to changes in balance, effectively preventing falls from different positions, such as standing or quadruped.

When testing infants for righting and equilibrium reactions, ensure movements are slow to observe appropriate responses. Some responses include:
- Tilting Forward: The infant should extend their head relative to the trunk and show equilibrium by extending limbs.
- Tilting Sideways: Expect abduction of limbs and adjustments in head and trunk position.
- Tilting Backward: Watch for flexion of the head, trunk, and shoulders as a response.

Continuous observation of these reflexes is crucial, particularly for premature infants who may display delays in integration and adjustment abilities.

Prematurity is defined as birth at or before 37 weeks of gestation. An age adjustment is often required to track developmental progress in premature infants by subtracting weeks from their current age, thereby aligning developmental assessments accurately.
For instance, a baby born two months early and aged eight months would be viewed as six months for assessment purposes.

Premature infants may exhibit delays in motor milestones, often linked to inadequate gestational development of vital reflexes like the Moro Reflex (startle reflex), and display characteristics of hypotonia, indicating potential lifelong consequences.

The session includes significant content focused on reflexes and their implications, and while quizzes and assignments are scheduled, future classes promise a lighter workload. Students are encouraged to prepare for an upcoming quiz assessing knowledge of this material.