Rachel johansson invisor5/25/2023 Signaler från periodontalreceptorer är nödvändiga för en normal reglering av låga krafter mellan käkarna, exempelvis då föda manipuleras och positioneras för att senare sönderdelas under tuggning. De flesta periodontalreceptorer svarar kraftigt på den initiala kontakten med föda, signalerar kontinuerligt information om belastningen då föda manipuleras mellan tänderna men ger lite eller ingen information om kraftnivån vid höga bit- och tuggkrafter. Periodontalreceptorer med olika funktionella egenskaper är specialiserade på att samla in information om specifika faser under normal bit- och tuggfunktion. Det gör att receptorerna är mycket känsliga för låga kraftnivåer. För en majoritet av receptorerna är relationen mellan tandbelastningens intensitet och nervsvarets impulsfrekvens inte linjär. Periodontalreceptorer signalerar information till hjärnan om tandbelastningens storlek och hastighet. Periodontalreceptorer är optimerade för att registrera krafter under normal funktion, och signalerar detaljerad information till hjärnan om var på tandbågen belastningen sker och riktningen på belastningen. A potential role for periodontal afferents in the spatio-intensive control of jaw actions is discussed. Moreover, since only a few afferents encode information about the rapid and strong force increase employed to bite through food, we conclude that subjects rely on signals from periodontal afferents to regulate the jaw muscles primarily when they first contact, manipulate and hold food substances between the teeth. If periodontal afferent information is not available, the control of the hold forces is severely impaired. Subjects spontaneously exert low contact forces matched to the sensitivity characteristics of these periodontal afferents when holding food substances between the incisors. These afferents efficiently encode food contact during biting and continuously discharge while food is held between the incisors. Similarly, the dynamic sensitivity is highest at low forces. Most afferents exhibit a marked “hyperbolic” relationship between the static discharge rate and the force amplitude the highest sensitivity to changes in static force is observed at forces below 1 N. Information about the magnitude of steady forces is made available in the mean firing-rate response of periodontal afferents. Populations of periodontal afferents, nevertheless, reliably encode information about both the teeth stimulated and the direction of forces applied to the individual teeth. Most afferents are tuned broadly to direction of force application, and about half respond to forces applied to teeth adjacent to the one to which the afferent distributes. We have found that all periodontal afferents adapt slowly to maintained loads. Signals were recorded from single afferents in the inferior alveolar nerve while controlled forces were applied to the teeth. Microneurography has been used to analyze the functional properties of human periodontal mechanoreceptors. We suggest that periodontal afferent signals are used to control jaw actions, particularly when subjects contact, manipulate and hold food prior to jaw power actions. In contrast, only a minority of the afferents encode the rapid and strong force increase required to bite through food. According to a quantitative model of responses in periodontal afferents based on these data, most afferents efficiently encode food contact during biting and continuously discharge while food is held between the incisors. Likewise, the dynamic sensitivity is markedly reduced at high forces. Most afferents exhibit a marked "hyperbolic" relationship between the steady state discharge rate and the force amplitude, featuring the highest sensitivity to changes in static force at forces below 1 N. All periodontal afferents show a slowly adapting response to maintained tooth loads. Nevertheless, populations of periodontal afferents can still encode information about the manner by which teeth are stimulated and the direction of forces applied to individual teeth. Most afferents are broadly tuned for diverse directions of tooth loads, and often respond to loading of teeth adjacent to the receptor bearing tooth. The force-encoding properties of human periodontal mechanoreceptors were characterized by microneurography.
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