LOCOMOTION IN TRAILING AS A SENSOMOTOR MECHANISM OF OLFACTORY NAVIGATION IN SERVICE DOGS

This lecture examines the locomotion of trailing dogs as a result of sensorimotor integration based on olfactory information processing. It shows that movement is the motor implementation of decisions made by the central nervous system based on the analysis of the odor field.

Navigation by scent trail is a complex biological process involving sensory detection, neural recognition, and motor implementation.

In mammals, movement is regulated by the sensorimotor system: sensory input → processing → motor output. In trailing, the key sensory input is olfactory.

Trailing is a method of navigating by scent. It is a purposeful working movement of a dog, formed by the sensorimotor system in response to the processing of olfactory information — it is not just the movement of a dog in space, but the motor expression of its sensory analysis. Locomotion is a motor response formed by the dog's nervous system based on olfactory information processing.

Thus, a dog's behavior in trailing has a sensory basis and consists of olfactory detection and neural transduction.

Olfactory detection involves a process in which volatile odor molecules enter the nasal cavity, come into contact with the olfactory epithelium, and activate receptor neurons. Science tells us that dogs have approximately 220-300 million receptors, a developed turbinate structure (to enhance air contact with receptors), and a large sensory surface area. Odor molecules bind to receptors in the olfactory epithelium, initiating a cascade of neural activation. Dogs have such exceptional morphofunctional features as an increased epithelial area, developed nasal conchae, and high receptor density.

Neural transduction, in simple terms, is the conversion of a chemical signal into an electrical impulse. Signals pass through the olfactory bulb to the piriform cortex, then to the limbic structures and orbitofrontal cortex. A neural pattern of smell is formed.

Without going into unnecessary detail, the following structures are involved in the central processing of signals:

1. The olfactory bulb, where the spatial neural pattern is formed.

2. The piriform cortex, which is responsible for recognizing the odor profile.

3. The limbic system, as the place where emotional significance and motivation are formed.

4. The orbitofrontal cortex, where behavioral decisions are made.

The processes of central signal processing form odor recognition, emotional significance, and decisions about action.

Confirmation of the smell initiates the activation of the dog's motor centers:

- the basal ganglia initiate motor programs,

- the motor cortex initiates movements,

- the cerebellum ensures coordination and accuracy.

This forms working locomotion.

Thus, each movement of a dog on a trail is not a random motor action, but a biologically justified response of the nervous system to olfactory information.Therefore, by observing locomotion, the handler actually "sees" the process of scent analysis.

In order to determine the odor gradient, the dog must move. The dog's movement is determined by the concentration gradient, binasal asymmetry, turbulent flow structure, and odor accumulation zones.

Odor navigation is implemented as a continuous cycle, otherwise known as a sensorimotor loop:

perception → analysis → movement → sensory data update.

This is a continuous closed loop. As it moves through space, the dog constantly updates its sensory data.

Biomechanics of search locomotion. A dog's search movement is characterized by stable adaptive patterns, the main (and most visible) of which are:

- dynamic stabilization of the dog's body,

- stride variability, and

- respiratory-motor synchronization.

Therefore, behavioral neuroscience defines locomotion as the implementation of cognitive processes through motor activity.

The scent field is subject to the laws of physics. The scent field is formed by turbulence, microclimate (temperature and humidity), and surfaces (relief), which determines the variability of motor strategies. Therefore, locomotion is adaptive, variable, and nonlinear.

Locomotion in trailing is a sensorimotor tool for olfactory navigation and requires the preservation of the purity of the sensory process.

The biomechanics of working locomotion (search movement) are characterized by:

- forward shift of the center of gravity

- stabilization of the torso

- synchronization of breathing and walking

- variability of the trajectory.

Biomechanical changes increase stability when moving with the head down, energy efficiency during prolonged work, and stability of sensory scanning.

The target scent acts as a discriminative stimulus, signaling that certain behavior will lead to reinforcement, a signal indicating that certain behavior will lead to reinforcement. The dog learns that if the scent is strong, moving forward is effective, and if the scent weakens, the strategy needs to be changed.

Thus, the scent is not just a sensory stimulus, but a signal to choose a behavioral strategy.

Understanding the neuromechanism of locomotion allows the handler to distinguish analysis from error, not to interfere with the cognitive process, to correctly interpret negative phases, and not to disrupt the sensorimotor loop. Without this knowledge, the handler tends to interfere with analysis, rush the dog, and disrupt the work.

The locomotion of a trailing dog is a tool for analyzing the environment. The dog's movement is an external manifestation of the neurosensory process of analyzing the presence or absence of the target scent. Locomotion is built in the following sequence: olfactory detection + neural recognition + sensorimotor integration + biomechanical implementation.

Locomotion is a language of analysis. Positive means "the scent is confirmed."   Negative means "the scent is not confirmed, the search for a solution is ongoing."

Therefore, locomotion is conditionally divided into two types: positive (there is a target smell) and negative (there is no target smell).

Positive locomotion assumes the presence of a target smell. When the profile match is stable:

- motor programs become stable, a stable vector appears,

- the need for corrections decreases

- movements are rhythmic and directed.

Stable sensory confirmation has specific characteristics:

- smooth traction,

- stable vector,

- steady pace,

- low trajectory variability.

When pattern matching decreases, the brain activates exploratory behavior, which leads to a decrease in speed, an increase in sensory scanning, and an expansion of the trajectory.

Therefore, negative locomotion (neurophysiology of uncertainty) is:

- slowing down,

- checking,

- turning of the head,

- arcs,

- "brackets,"

- refusals,

- returns,

- stops (micro-stops).

Negative indications can be divided into:

- sensory (clarification of information), which include slowing down, micro-stops, and head turns.

- spatial (search for field structure), such as arcs, "brackets," casting.

- retrospective (verification of reliability), namely returns and repeated passes.

- cognitive pauses, expressed as freezing and stopping.

The dog "thinks with its body": movement generates new sensory information, and sensory perception corrects movement.

From the above, it becomes clear that negative indications are not "movement errors" but a motor expression of a cognitive state of uncertainty. When the scent pattern match decreases, the dog's brain switches from confirmed navigation to exploratory search mode. Neural networks of orientational behavior are activated.

Each form of negative locomotion has a functional explanation.

For example, the slowing mechanism is associated with decreased confidence and inhibition of motor programs. Slowing increases the density of sensory scanning.

The micro-stop mechanism is a pause to stabilize breathing and enhance olfactory selection. The dog increases the accuracy of odor pattern comparison.

Head turns are a binasal gradient check. Comparison of concentrations on the right and left to find the vector.

Arcs are an expansion of the search area when the gradient is blurred. The dog searches for an area with a more pronounced scent signal.

 "Brackets" are a pendulum scan of the boundaries of the scent corridor to determine its width and the direction of the scent cone.

Checks are necessary for spatial reconstruction of the scent field. By checking, the dog searches for a new point of pattern matching.

Returns are a check of the last zone of sensory reliability to reconfirm the information.

Refusals or "freezes" are associated with a temporary blockage of motor programs due to sensory reassessment of the situation.

Thus, negative indications are the diagnostic language of olfactory uncertainty. This is not a behavioral failure, but active cognitive work.

The form of negative indications is influenced by the structure of the olfactory cone. The type of negative locomotion directly depends on the physics of the environment. Below is a small table showing the approximate dependence of negative manifestations on the environment.

Environment	Type of negative
Turbulence	Chaotic arcs
Weak gradient	Slowdown
Trail break	Returns
Odor accumulation	Circles
Crossings	Casting (checks)
Wind transport	Vector displacement

Locomotion as a sensory stimulus is formed from operant learning, motivation, and reinforcement histories.

External intervention—mechanical leash control, kinesthetic cues, pace changes by the handler, visual guidance—disrupts the sensorimotor loop. The dog's movement becomes a reaction to the person rather than to the scent.

The dog's movement is formed through: stimulus → action → result → reinforcement.

From a behaviorist perspective, locomotion in trailing is not only a neuromotor process, but also a learned operant behavior controlled by consequences.

Working locomotion has an operant basis for formation when working movement patterns are reinforced through positive reinforcement: finding a person leads to a reward. The behavioral chain is reinforced.

Quick and easy finding of a person and substantial rewards, which are elements of intensive exercise, quickly form working movement patterns. Accurate scent decisions need to be reinforced more often than random ones.

Repetition of successful cycles creates automation of motor programs, leads to a reduction in cognitive load, and creates stable working rhythms.  Locomotion becomes energy-efficient and behaviorally stable.

It is important to understand that in conditions of scent uncertainty, the dog chooses the strategy with the highest probability of success: following the target scent, moving along the freshest trail, visual pursuit, or orienting itself toward the handler. If alternative strategies have been reinforced in the past, they compete with scent work.

Incorrect training forms false behavioral algorithms that masquerade as working locomotion and reinforces dependence on the leash,  reading the handler's body language, guessing the direction, reacting to people's movements, etc.

Trailing is not just sensorimotor navigation. It is also a decision-making system that the dog is trained to use. In other words, the dog moves in the wayas it has been taught to respond to scent. The handler's role is to regulate the conditions, but not to control the dog's movement. Therefore, the handler's task is not to distort the sensory process (not to disrupt the sensorimotor loop), to remain neutral, and to read the dog's biomechanics and behavioral signals.

Studies show that dogs generalize their experiences, and if the start (turn, stop) is always "prompted," then waiting for a cue becomes the norm. If the trails are always "sterile," then resistance to contamination decreases.

Therefore, variability of all factors, including the environment, is important in training, and control "blind" trails are necessary.

Following the target scent in itself reduces uncertainty, creates predictability in the environment, and activates search motivation. The search becomes internally motivated. In such cases, we talk about self-reinforcing behavior.

Handlers often encounter the definition that understanding negatives is the key to reading a dog's work.

The practical interpretation of negative locomotion is extremely important. If the handler reads the negative correctly, then he:

- does not interfere with analysis,

- does not interfere with the leash,

- allows the dog to complete the check,

- does not mistake analytical work for mistakes.

Locomotion is an indicator of the purity of olfactory work. However, if the movement is "beautiful and confident" but the smell is not read, then the work is broken.

Working locomotion can be ruined. And it can be restored. This is not the dog's "character" — it is a sensorimotor skill that is formed by training and the environment.

 "Corrupted locomotion" is a situation where a dog's movement ceases to be the result of olfactory analysis and becomes a reaction to external factors. Behaviorally corrupted locomotion is incorrectly reinforced behavioral chains.

The most well-known distortion of locomotion is when a dog moves without following a scent.

What spoils locomotion?

1. Kinesthetic cues from the handler

- steering with the leash

- pulling "to the side"

- showing the turn with the body

- accelerating/braking with the body

As a result, the dog reads the handler rather than the scent.

2. Predictable starts, when the dog is placed with its nose on the trail or when the direction is always known and the trail is "hinted" (even unconsciously). As a resultthe dog's spatial memory is activated instead of olfactory navigation.

3. Behavioral retraining. If, during training, the dog was reinforced for moving "by the freshest scent," visual pursuit, reaction to the movement of the decoy, and guessing, then the dog develops an alternative search strategy.

4. Excessive excitement. Disruption of the working balance leads to impulsive movement, reduced accuracy of analysis, and creates "jerky" locomotion.

5. Too frequent interventions, when the handler does not allow the dog to complete the check, interrupts the negative, rushes and fusses, destroying the sensorimotor loop of analysis.

Impaired locomotion visually looks like:

- "empty" pulling without scent confirmation,

- movement in a straight line without checks (without negatives),

- absence of negative indications,

- dependence on the leash,

- sharp, mechanical turns.

These are signs of motor automatism without sensory control.

Locomotion errors can be corrected. This is because locomotion involves neuroplasticity and operant learning. The brain can be retrained. However, this process is complex, lengthy, and requires patience.

Restoring locomotion involves launching motor programs with a full sensory trigger—restoring the connection between "smell → analysis → movement." Behaviorally impaired locomotion requires reinforcement of correct behavioral chains. Restoring locomotion requires "reprogramming" through differential reinforcement.

Locomotion is restored by nullifying the influence of the handler and restoring sensory autonomy.

The handler must rebuild their approach to handling and ensure a neutral position behind the axis, zero body cueing, and remember that the leash is a signal conductor from the dog, not a steering wheel.

Correcting locomotion involves creating conditions in which the dog can once again search on its own, make mistakes on its own, and check on its own. Without interference. The goal is верн Thus, every movement of the dog on the trail is not a random motor action, but a biologically justified response of the nervous system to olfactory information.Therefore, by observing locomotion, the handler actually "sees" the process of scent analysis, or "the work of the nose."

The handler must mark negatives, allow for analysis and negative phases (arcs, casting, returns, stops). Negatives are the main tool for repairing locomotion.

In addition, motivation will need to be rebuilt.

It is necessary to reinforce correct analysis, independent decisions, and sustained retention.

The time required to restore locomotion depends on many factors. These include the duration of incorrect movement, the dog's sensitivity, breed characteristics, the quality of the rehabilitation method, and the skills of the handler.

Thus, minor distortions can be corrected in 2–4 weeks, stable patterns in 2–4 months, and severe cases often require complete reset.

Locomotion can be ruined by interference, but restored by the right technique. Thus, it is not a "talent" but a customizable training system.

Locomotion is the language of olfactory field analysis. The clearer the sensory process, the more honest the movement. Trailing is navigation through smell, and movement is its visible part.

SCIENTIFIC SOURCES

Smell and Neurophysiology

1. Shepherd, G. M. (2004). The Human Sense of Smell: Are We Better Than We Think? PLoS Biology.

2. Buck, L., & Axel, R. (1991). A novel multigene family may encode odorant receptors. Cell.

3. Mori, K., et al. (2006). Olfactory neural circuitry and odor information processing. Progress in Neurobiology.

Sensory-motor integration

4. Shadmehr, R., & Krakauer, J. W. (2008). A computational neuroanatomy for motor control. Experimental Brain Research.

5. Wolpert, D. M., et al. (2011). Principles of sensorimotor learning. Nature Reviews Neuroscience.

Navigation by smell

6. Porter, J., et al. (2007). Mechanisms of scent-trailing in humans. Nature Neuroscience.

7. Gire, D. H., et al. (2016). Walking behavior shapes olfactory sampling. Journal of Neuroscience.

Biomechanics of movement

8. Alexander, R. McN. (2003). Principles of Animal Locomotion. Princeton University Press.

Behavioral neuroscience

9. Wilson, M. (2002). Six views of embodied cognition. Psychonomic Bulletin & Review.

   
   

   By SERVICE DOGS. Irina Brunina