Neural Theories and Clinical Considerations for Speech Issues: An Orofacial Research Insight

Introduction

Human sounds, which is the basis, of course, for human speech produced by a coordinated action of your speech organs, is the basis by which individuals can communicate effectively. Sound is indeed the root cause of human language, which, as we know it, is the singular, unitary phenomenon that has had an everyday genetic basis for centuries. While it is innate as a part of your speech, language is also learned that varies across different continents around the world.

Language production, as defined in medical terms by researchers, occurs when all the organs involved in producing speech are evolved enough for the purposes of mastication and respiration as well. For individuals clinically suffering from respiratory or masticatory disorders or diseases, speech production would be a major clinical issue that can be a setback to the oral and systemic quality of life.

In many genetic as well as behavioral diseases or disorders, researchers have studied the cause of speech loss, known clinically as aphasia. This has also helped researchers understand the neural basis of language and how the orofacial structures influence speech production in the individual.

What Are the Neural Mechanisms of Speech Production and Processing?

Speech involves multiple regions of the brain, and those include:

1. Broca’s area is located in the left frontal lobe. This area is critical for speech production. Damage to the Broca’s area can lead to aphasia.

2. Wernicke’s area is present in the left temporal lobe. This area is required for language comprehension. Receptive aphasia can be caused due to lesions in this area.

3. The motor cortex controls the muscles involved in articulation, such as the lips, tongue, and vocal cords. The hypoglossal and vagus nerves transmit signals from the brainstem to these muscles for proper speech production.

4. Auditory feedback is important for monitoring and adjusting speech.

What Are the Theories of Neurologic Affliction Leading to Speech Disturbances or Aphasia?

By several behavioral studies and research analysis techniques, medical and neurologic research states that aphasias or loss of speech would occur in some individuals while in others, the improper speech or speech-related disturbances that involve different areas of the cerebral hemispheres in human beings. In most cases, clinical research demonstrates that aphasias are usually restricted to the left side of the cerebral hemisphere. At the same time, it is rare or less common to decipher the aphasia affecting the right cerebral hemispheres. The damage to the left cerebral hemisphere of the brain would affect the dominant language-centered region responsible for speech production. The left cerebral hemisphere is hence associated with specific language-centered cerebral areas that are higher than in the right cerebral hemisphere of the brain- which is the reason why neurologists have proposed several theories or hypotheses regarding the speech disorders linked to neurologic diseases within this region of the brain.

Of all these theories, the accepted ones that would influence the orofacial cavity in a negative way and create speech-related disturbances and issues in language production are explained by these two major hypotheses:

• Connectionist Theory: This theory suggests that because language is generally processed by the decoding of the motor expressions in the Wernicke's area of the brain, to the higher expression within the Broca's area of the brain or other areas of the cerebral cortex- this theory of language production or speech formation would possibly be useful in researchers deciphering the reason for aphasias.

• Modular Theory of Language: This has replaced the traditionally accepted hypothesis or the above-explained connectionist theory stating that language production in the brain to your oral cavity and then resulting in speech subsequently is a coordinated processing across parallel areas of your brain or your neurocognitive system-which are responsible for performing neurocognitive tasks.

How Is Speech Produced?

Let us understand the normal mechanism of speech formation. When the vocal cords extend from the vocal folds as an acoustic tube of variable cross-section till the lips- produce voiced sounds, then speech would be produced. When you try to speak, there is a raised air pressure within the lungs that forces the air past the vocal folds, causing them to vibrate and, in turn, produce sounds. By the process of neurocognitive resonance and articulation, intelligible sounds are produced by the human brain, depending on the parallel working of the language center in the brain that phrases your speech.

What Are the Clinical Considerations in the Oral Cavity for Resolving Speech Issues?

In the oral cavity, there are several clinical considerations.

1. If the patient's oral cavity is altered by proper alignment of dentition through orthodontic or prosthodontic treatment speech, related disturbances might resolve as per the latest clinical research in the dental literature. In many cases of malocclusion, where patients would not be able to bite correctly or suffer from orofacial skeletal discrepancies, then speech-related disorders can be a possibility. Post orthodontic treatment, in many cases in medical literature, treatment of malocclusion, especially in younger children and adolescents, can help in managing speech issues.

2. Speech articulation is also a clinical consideration by dentists for patients wearing fixed or removable dentures. While denture placement may not create effective speech as much as natural dentition does, it is a known fact that speech is at least partially improved, usually by proper fitting denture placement that allows orofacial musculature to make fine adjustments between the tongue and dentition to produce normal sounds.

3. Another primary clinical consideration for maxillofacial surgeons or otolaryngologists is the size of the nasopharynx. Any excess interference in your nasal pathway, in the size of the nasopharynx or within the neuromuscular structure supplying the palate, such as in cleft palate, adenoidal growth cases, or loss of nasal resonance, can also interfere with speech production and cause severe issues.

Conclusion

The oral cavity and the nasopharynx are innate structures responsible for speech production. Dental and maxillofacial surgeons also need to know the normal physiology of speech production, which is the basis of language. Early diagnosis and management of speech issues can be resolved to the overall quality of life.