Neuroscientists Alain Berthoz (France) and Hans-Dieter Grüsser (Germany) studied how the brain develops and integrates visual directionality, meaning the capacity of neurons to respond preferentially to a specific orientation (horizontal or vertical) or direction of movement. Their work addresses:
- The influence of directional visual stimulation from birth,
- The concept of geometric selection in early sensory processing,
- The role of extra-visual signals (proprioceptors from eye and neck muscles) in cortical directionality.
Early Directional Biases in Infants
From the first weeks of life, the visual system shows orientation preferences. Psychological studies have shown that newborns prefer to fixate on horizontal stripes more than vertical ones. Their horizontal eye-tracking movements are also smoother. These behaviors suggest that the visual cortex is initially organized to respond differently to specific spatial orientations, possibly due to environmental structure (horizon, gravity, posture).
Geometric Selection Concept (Berthoz)
Alain Berthoz proposed that early sensory processing organizes spatial information along predefined directional axes. In subcortical visual pathways, specific nuclei respond preferentially to horizontal or vertical movements, aligned with the geometry of vestibular receptors. This alignment facilitates multisensory integration between visual input and body orientation.
Eye and Neck Proprioception in Directional Perception
Hans-Dieter Grüsser demonstrated that visual cortical neurons respond not only to retinal inputs but also to signals from eye and neck muscle proprioceptors. This means that a neuron's preferred direction can depend on head or eye position. This mechanism allows the brain to stabilize visual perception despite body movement.
Other studies showed that depriving the eyes of movement during development prevents proper orientation tuning of visual neurons. Thus, eye movements serve as organizing signals for the visual cortex. Neck proprioceptors also help calibrate visual orientation by referencing head position to determine where "straight ahead" is.
Visual Processing Pathways: Parvo and Magno
Two Main Functional Pathways
| Characteristic | Parvocellular Pathway | Magnocellular Pathway |
|---|---|---|
| Cells | L and M cones (small P cells) | Cones and M-type cells |
| Receptive field | Small (central vision) | Large (peripheral vision) |
| Spatial frequency | High (fine detail) | Low (global shapes) |
| Temporal frequency | Low (slow/static stimuli) | High (fast/moving stimuli) |
| Color sensitivity | Yes | Minimal (mostly achromatic) |
| Function | Discrimination, recognition | Orientation, reflex, visuomotor coordination |
Color and Sensorimotor Context
- 🔴 Red: processed by L-cones, classically routed through the parvocellular pathway. However, when red is intense, wide, or diffuse, it may trigger magnocellular-like behavioral responses (blurred perception, reflexive, global).
- 🔵 Royal blue: processed by S-cones (koniocellular pathway), but when perceived with fine contrast, it may also activate parvocellular-like processing (focused, precise, attention-driven).
Functional Integration: Vision and Coordination
The perception of visual targets—specifically their color (e.g., red or blue) and orientation (vertical or horizontal)—can modulate motor performance. When a target's visual properties align with an individual's preferred visual processing pathway (parvocellular or magnocellular), the central nervous system (CNS) processes the visual input more efficiently. This reduces the cognitive and perceptual load, freeing up neurological resources for motor control and coordination.
For example, an athlete with a magnocellular dominance may respond more effectively to a large, low-detail red stimulus (e.g., red horizontal line), which is processed quickly and unconsciously. This enables smoother, more reflexive movement. Conversely, an athlete with a parvocellular preference may benefit from a focused, high-contrast blue target, enhancing precision in complex motor tasks.
This perceptual-motor alignment facilitates faster decision-making, improved timing, and better movement quality, particularly in high-performance settings where milliseconds and millimeters matter.
In a sensorimotor context, certain color/orientation combinations may enhance motor coordination by reducing visual processing load, allowing better allocation of CNS resources.
| Visual Profile | Optimal Stimulus | Processing Mode | Motor Effect |
|---|---|---|---|
| Low-frequency (magno) | 🔴 Bright diffuse red | Rod-like / magnocellular | Fluidity, automation, release |
| High-frequency (parvo) | 🔵 Focused royal blue | Cone-like / parvocellular | Precision, control, activation |
This logic is clinically observed in the use of visual targets with color and orientation variations (e.g., "red horizontal", "blue vertical"), tailored to each athlete’s visual-motor dynamics. However, the ideal orientation (horizontal or vertical) may vary and is not consistently observed clinically.
These visual preferences are individual to each person, and their expression can vary in intensity depending on the individual’s baseline, their current energy level, and the context of the activity. This variability means that optimal visual stimulation should be personalized, flexible, and adjusted based on the athlete’s state and environment.
Supporting Evidence from Scientific Research
Scientific studies also highlight the impact of visual processing pathways on eye-hand coordination. For instance, Carther-Krone & Marotta (2022) demonstrated that visual stimuli aligned with magnocellular or parvocellular characteristics can significantly influence the accuracy and timing of eye-hand movements. This suggests that motor actions guided by vision, such as catching or striking, benefit when the visual input is optimized for the individual's dominant processing mode.
Recent scientific studies reinforce the idea that visual stimuli designed with the characteristics of magnocellular and parvocellular pathways in mind can have a significant impact on motor coordination and athletic performance. For instance:
- The parvocellular pathway, responsible for processing color and fine detail, plays a key role in precise, conscious motor control. (Ghodrati et al., 2020)
- The magnocellular pathway, which processes motion, contrast, and peripheral information, supports fast, reflexive visuomotor responses. Stimuli that emphasize luminance contrast and low spatial frequency tend to activate this pathway. (Carther-Krone & Marotta, 2022)
These findings support clinical observations that aligning visual stimuli (color, contrast, frequency) with an athlete’s dominant processing mode can enhance performance. Such alignment improves the efficiency of CNS processing and frees cognitive resources for more effective movement control.
Conclusion
Visual orientation (vertical/horizontal), visual frequency processing (parvo/magno), and the sensory characteristics of color (bright red vs. royal blue) interact in complex yet predictable ways. Based on foundational research by Berthoz and Grüsser, it is possible to develop personalized visual stimulation approaches to enhance athletic coordination. These approaches bridge vision science and performance, integrating early sensory biases, proprioceptive feedback, and functional visual pathways.
The clinical outcomes and practical observations gathered so far strongly encourage the development of targeted scientific studies. Progress in neuroscience often begins with empirical insights from the field, which then pave the way for more rigorous experimental validation. In this context, personalized visual stimulation (adapted to frequency preferences, colors, and sensorimotor states) opens promising perspectives for optimizing motor coordination.
Key References:
- Berthoz, A. (1993). Physiologie de la perception et de l’action, Collège de France.
- Grüsser, O.-J. & Grüsser-Cornehls, U. (1972). Interaction of vestibular and visual inputs in the visual system, Brain Function V.
- Buisseret, P. & Gary-Bobo, E. (1979). Neurosci. Lett.
- Buisseret, P. (1995). Physiol. Rev., 75(2), 323–338.