Читать книгу Dental Neuroimaging - Chia-shu Lin - Страница 32

It would be contradictory to talk about an invasive imaging method if we strictly define neuroimaging as a non‐invasive approach. However, some invasive approaches have provided crucial conceptual advancement in neuroimaging. For example, in electrocorticography (ECoG), experimenters detect brain signals using a meshwork that consists of multiple electrodes. This meshwork is overlaid on the dura of the brain, and therefore, the response of the electrodes at different positions can be (though roughly) mapped to the anatomical region of the brain (Gazzaniga et al. 2019). The method was limited to patients who received brain surgery. ECoG reveals the feasibility of brain mapping, i.e. to map the association between the geometric features of the brain and mental functions, a fundamental element of modern neuroimaging.

Figure 1.2 A general view of the neural circuitries of the brain mechanisms of orofacial functions. The circuitries between the central and peripheral sites (i.e. pathways labelled in blue and red) are investigated primarily via animal models. Notably, the circuitries within the brain (i.e. the intracortical pathways labelled in black) have not been fully elucidated.

Source: Avivi‐Arber and Sessle (2018). Reproduced with permission of John Wiley and Sons.

Table 1.2 Selected findings (since 2010)^a of neuroimaging research, which are related to the issues of the ‘landmark discoveries or concepts’ of oral neuroscience (Iwata and Sessle 2019), as quoted in field (A) to (G).

Source: Field (A) to (G) based on Iwata and Sessle (2019).

Source	Participants	Methods	Major findings
(A) ‘Presentation of the gate control theory of pain’
Brügger et al. (2012)	Healthy adults	fMRI	‘Cerebral toothache intensity coding on a group level can thus be attributed to specific subregions within the cortical pain network’.
Gustin et al. (2011)	TNP and TMD patients	sMRI, MRS	‘…neuropathic pain conditions that result from peripheral injuries may be generated and/or maintained by structural changes in regions such as the thalamus’
(B) ‘… the multidimensionality and biopsychosocial aspects of pain and their application to improved diagnosis and management of orofacial pain conditions’
Youssef et al. (2014)	Painful TN and TMD patients	ASL‐MRI	‘… non‐neuropathic pain was associated with significant CBF increases in regions commonly associated with higher‐order cognitive and emotional functions …’
Weissman‐Fogel et al. (2011)	Patients with nontraumatic TMD	fMRI	‘… the slow behavioural responses in idiopathic TMD may be due to attenuated, slower and/or unsynchronized recruitment of attention/cognition processing areas’.
(C) ‘Discovery of trigeminal nociceptive afferents and their modulation by processes within orofacial tissues …’/‘Discovery of the plasticity of the nociceptive neurons …’
Gustin et al. (2012)	Patients with painful TN and painful TMD	fMRI, ASL‐MRI	‘… while human patients with neuropathic pain displayed cortical reorganization and changes in somatosensory cortex activity, patients with non‐neuropathic chronic pain did not’.
Moayedi et al. (2012)	TMD patients	DTI	‘… novel evidence for CNV microstructural abnormalities that may be caused by increased nociceptive activity, accompanied by abnormalities along central WM pathways in TMD’.
(D) ‘Discovery of nociceptive neurons in the brain and their modulation by intrinsic CNS circuits and endogenous mediators…’
Desouza et al. (2013)	Patients with idiopathic trigeminal neuralgia	sMRI	‘These findings may reflect increased nociceptive input to the brain, an impaired descending modulation system that does not adequately inhibit pain …’
Abrahamsen et al. (2010)	TMD patients	fMRI	‘… hypnotic hypoalgesia is associated with a pronounced suppression of cortical activity …’
(E) ‘Definition of the central pattern generators for chewing and swallowing’
Lowell et al. (2012)	Healthy adults	fMRI	‘The greater connectivity from the left hemisphere insula to brain regions within and across hemispheres suggests that the insula is a primary integrative region for volitional swallowing in humans’.
Quintero et al. (2013)	Healthy adults	fMRI	‘… demonstrated that brain activation patterns may dynamically change over the course of chewing sequences’.
(F) ‘… discovery of the plasticity of sensorimotor cortex and other CNS regions in relation to orofacial sensorimotor control, learning and adaptation to injury and other changes in orofacial tissues’
Kimoto et al. (2011)	Edentulous patients wearing a CD and an IOD	fMRI	‘…differential neural activity in the frontal pole within the prefrontal cortex between the two prosthodontic therapies – mandibular CD and IOD’.
Luraschi et al. (2013)	Edentulous patients wearing a CD	fMRI	‘Changes in brain activity occurred in the adaptation to replacement dentures …’
(G) ‘Delineation of peripheral processes and CNS circuits underlying touch, temperature, taste and salivation, including the discovery of a fifth taste, umami’
Trulsson et al. (2010)	Healthy adults	fMRI	‘… PDLMs, and SA II‐type receptors in general, may be involved in one aspect of the feeling of body ownership’.
Nakamura et al. (2011)	Healthy adults	fMRI	‘The peaks of the activated areas in the middle insular cortex by umami were very close to another prototypical taste quality (salty)’.

ASL‐MRI: arterial spin labelling magnetic resonance imaging; CBF: cerebral blood flow; CD: complete denture; CNV: the trigeminal nerve; DTI: diffusion tensor imaging; fMRI: functional magnetic resonance imaging; sMRI: structural magnetic resonance imaging; IOD: implant‐supported denture; MRS: magnetic resonance spectroscopy; PDLM: periodontal ligament mechanoreceptor; SA: slowly adapting; TMD: temporomandibular disorders; TN: trigeminal neuropathy; TNP: trigeminal neuropathic pain; WM: white matter.

^a The survey is performed using Google Scholar, with the date of publication ranged from 1 January 2010 to 30 May 2021.

Table 1.3 Selected findings (since 2010) of brain imaging research related to the clinical disciplines of dentistry^a.

Clinical topics a	Potential clinical implications	Source
Prosthodontic treatment	For edentulous patients, reduced prefrontal activation associated with tooth loss may be prevented by chewing with a denture.	Kamiya et al. (2016)
Prosthodontic treatment	The adaptation to replacement of dentures may be associated with changes in brain activity during oral motor tasks.	Luraschi et al. (2013)
Prosthodontic treatment	Adaptative chewing experience induced by palate coverage was associated with changes in brain activity associated with motor learning.	Inamochi et al. (2017)
Dental implant	In rats, tooth loss and installing dental implants may be associated with neuroplasticity at the facial somatosensory/motor region.	Avivi‐Arber et al. (2015)
Dental implant	Osseoperception may be associated with the brain and the processing of primary and secondary somatosensory areas.	Habre‐Hallage et al. (2012)
Orthodontic treatment	Functional appliances may work as exercise devices for neuromuscular changes associated with muscle adaptation and brain activation.	Ozdiler et al. (2019)
Orthodontic treatment	In rats, inflammation induced by tooth movement may relate to the activity of the somatosensory cortex and insula, which may be associated with higher sensitivity to pain.	Horinuki et al. (2015)
Occlusion	Occlusal discomfort may be associated with attention and/or self‐regulation of the uncomfortable somatosensory experience.	Ono et al. (2015)
Occlusion	Regulation of occlusal force and periodontal sensation was modulated by prefrontal activity.	Kishimoto et al. (2019)
Periodontal treatment	In rats, mechanical and electrical stimuli may respectively excite activation at the primary and secondary somatosensory cortices.	Kaneko et al. (2017)
Periodontal and systemic health	Periodontal inflammatory/infectious burden is associated with the accumulation of amyloid‐β plaques, a key feature of Alzheimer's disease.	Kamer et al. (2015)
Periodontal and systemic health	Poor periodontal health may be associated with lacunar infarction, a potential cause of dementia.	Taguchi et al. (2013)

^a All the search was performed using PubMed, with date of publication ranged from 1 January 2010 to 31 May 2021.