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Proceedings of the National Academy of... Feb 2024Auditory dorsal and ventral pathways in the human brain play important roles in supporting speech and language processing. However, the evolutionary root of the dual...
Auditory dorsal and ventral pathways in the human brain play important roles in supporting speech and language processing. However, the evolutionary root of the dual auditory pathways in the primate brain is unclear. By parcellating the auditory cortex of marmosets (a New World monkey species), macaques (an Old World monkey species), and humans using the same individual-based analysis method and tracking the pathways from the auditory cortex based on multi-shell diffusion-weighted MRI (dMRI), homologous auditory dorsal and ventral fiber tracks were identified in these primate species. The ventral pathway was found to be well conserved in all three primate species analyzed but extend to more anterior temporal regions in humans. In contrast, the dorsal pathway showed a divergence between monkey and human brains. First, frontal regions in the human brain have stronger connections to the higher-level auditory regions than to the lower-level auditory regions along the dorsal pathway, while frontal regions in the monkey brain show opposite connection patterns along the dorsal pathway. Second, the left lateralization of the dorsal pathway is only found in humans. Moreover, the connectivity strength of the dorsal pathway in marmosets is more similar to that of humans than macaques. These results demonstrate the continuity and divergence of the dual auditory pathways in the primate brains along the evolutionary path, suggesting that the putative neural networks supporting human speech and language processing might have emerged early in primate evolution.
Topics: Animals; Humans; Callithrix; Diffusion Magnetic Resonance Imaging; Language; Auditory Cortex; Auditory Pathways; Macaca; Neural Pathways; Brain Mapping
PubMed: 38377216
DOI: 10.1073/pnas.2313831121 -
Spine Deformity Mar 2024There is great controversy about the etiologic origin of adolescent idiopathic scoliosis. Multiple theories have been suggested, including metabolic aspects, endocrine... (Review)
Review
PURPOSE
There is great controversy about the etiologic origin of adolescent idiopathic scoliosis. Multiple theories have been suggested, including metabolic aspects, endocrine dysfunction, neurological central abnormalities, genetic predisposition and epigenetic factors involved in the development of scoliosis. However, there has always been speculations based on human biomechanical behavior.
METHODS
In this article, we performed a literature review on the biomechanical traits of human posture, and the proposed theories that explain the special characteristics present in idiopathic scoliosis.
RESULTS
The current theory on the etiopathogeneis of AIS suggests that dorsally directed shear loads acting on a preexisting axial plane rotation, in a posteriorly inclined sagittal plane of a growing patient, together with disc maturation, collagen quality at this phase of development and immaturity of proprioception, is the perfect scenario to spark rotational instability and create the three-dimensional deformity that defines idiopathic scoliosis.
CONCLUSION
The unique spinal alignment of human bipedalism, gravity and muscle forces acting straight above the pelvis to preserve an upright balance, and the instability of the soft tissue in a period of growth development, is an appealing cocktail to try to explain the genesis of this condition in humans.
Topics: Adolescent; Humans; Scoliosis; Spine; Kyphosis; Rotation; Pelvis
PubMed: 37975988
DOI: 10.1007/s43390-023-00787-7 -
Neurochemistry International Dec 2023Parvalbumin is one of the calcium-binding proteins. In the spinal cord, it is mainly expressed in inhibitory neurons; in the dorsal root ganglia, it is expressed in... (Review)
Review
Parvalbumin is one of the calcium-binding proteins. In the spinal cord, it is mainly expressed in inhibitory neurons; in the dorsal root ganglia, it is expressed in proprioceptive neurons. In contrast to in the brain, weak systematization of parvalbumin-expressing neurons occurs in the spinal cord. The aim of this paper is to provide a systematic review of parvalbumin-expressing neuronal populations throughout the spinal cord and the dorsal root ganglia of mammals, regarding their mapping, co-expression with some functional markers. The data reviewed are mostly concerning rodentia species because they are predominantly presented in literature.
Topics: Animals; Calcium-Binding Proteins; Parvalbumins; Ganglia, Spinal; Spinal Cord; Neurons; Mammals
PubMed: 37967669
DOI: 10.1016/j.neuint.2023.105634 -
Cureus Jul 2023Background The purpose of the study was to provide a practical landmark for localizing the dorsal branch of the ulnar artery and nerve, to approach for microsurgical...
Background The purpose of the study was to provide a practical landmark for localizing the dorsal branch of the ulnar artery and nerve, to approach for microsurgical flaps, for harvesting nerve grafts and also to avoid these nerves during insertion of wrist arthroscopy portals. Material and methods Forty adult cadaveric upper limbs (20 right and 20 left) were dissected for localizing the dorsal branches of the ulnar artery and nerve. The ramification patterns of the nerve were mapped. The wrist arthroscopy portals are located radial and ulnar to the tendon of extensor carpi ulnaris at the level of the wrist joint, and their designated names are '6R & 6U', respectively. The distance of branches of the nerve from the 6U and 6R portals for wrist arthroscopy was recorded. Results The present study has delineated a subcutaneous dorsomedial triangular area in the distal forearm. The construction of this triangle uses palpable landmarks, i.e. pisiform bone, styloid process and subcutaneous border of the ulna. The measure of the sides of the triangle uses proportion rather than absolute measurements and hence is person specific. The dorsal branches of the ulnar nerve and artery are consistently given off in the triangle's upper third and middle third, respectively. Four branching patterns have been mapped, with one dominant pattern in 67.5% of limbs. In three-fourths of cases, one branch of the dorsal branch of the ulnar nerve consistently overlies the 6U portal and hence runs a higher risk of injury. Conclusion The study suggests more practical, accurate, reliable and consistent surface landmarks for the localization of the dorsal branch of the ulnar artery and nerve for reconstructive microsurgery for distal hand defects.
PubMed: 37593310
DOI: 10.7759/cureus.41981 -
The American Journal of Pathology Dec 2023Despite the development of antiretroviral therapy (ART), HIV-associated distal sensory polyneuropathy remains prevalent. Using SIV-infected rhesus macaques, this study...
Neuroinflammation in the Dorsal Root Ganglia and Dorsal Horn Contributes to Persistence of Nociceptor Sensitization in SIV-Infected Antiretroviral Therapy-Treated Macaques.
Despite the development of antiretroviral therapy (ART), HIV-associated distal sensory polyneuropathy remains prevalent. Using SIV-infected rhesus macaques, this study examined molecular mechanisms of peripheral and central sensitization to infer chronic pain from HIV infection. Previous studies identified atrophy in nociceptive neurons during SIV infection, which was associated with monocyte infiltration into the dorsal root ganglia (DRG). However, the sensory signaling mechanism connecting this pathology to symptoms remains unclear, especially because pain persists after resolution of high viremia and inflammation with ART. We hypothesized that residual DRG and dorsal horn neuroinflammation contributes to nociceptive sensitization. Using three cohorts of macaques [uninfected (SIV-), SIV-infected (SIV+), and SIV infected with ART (SIV+/ART)], this study showed an increase in the cellular and cytokine inflammatory profiles in the DRG of SIV+/ART macaques compared with uninfected animals. It found significant increase in the expression of nociceptive ion channels, TRPV1, and TRPA1 among DRG neurons in SIV+/ART compared with uninfected animals. SIV-infected and SIV+/ART animals showed reduced innervation of the nonpeptidergic nociceptors into the dorsal horn compared with uninfected animals. Finally, there were a significantly higher number of CD68 cells in the dorsal horn of SIV+/ART macaques compared with uninfected animals. In summary, these data demonstrate that neuroinflammation, characteristics of nociceptor sensitization, and central terminal atrophy persists in SIV+/ART animals.
Topics: Animals; HIV Infections; Simian Acquired Immunodeficiency Syndrome; Simian Immunodeficiency Virus; Nociceptors; Macaca mulatta; Neuroinflammatory Diseases; Ganglia, Spinal; Atrophy
PubMed: 37734588
DOI: 10.1016/j.ajpath.2023.08.014 -
European Review For Medical and... Oct 2023In this retrospective and multicentric study, we investigated applied surgical methods in rhinoplasty for crooked nose deformity.
OBJECTIVE
In this retrospective and multicentric study, we investigated applied surgical methods in rhinoplasty for crooked nose deformity.
PATIENTS AND METHODS
The retrospective data for 300 crooked nose deformity cases (191 males and 109 females) were used in our study. Classification of the initial deformities was performed as (1) I-shaped crooked nose deformity, (2) C-shaped crooked nose deformity, (3) Reverse C-shaped crooked nose deformity, and (4) S-shaped crooked nose deformity. As an operation technique, L-strut septoplasty was performed. The applied surgical methods in rhinoplasty to correct the crooked nose are evaluated and classified.
RESULTS
Our results showed that initial deformities in crooked nose patients were I-shaped crooked nose deformity (34%), C-shaped crooked nose deformity (28%), Reverse C-shaped crooked nose deformity (21.3%), and S-shaped crooked nose deformity (16.7%). L-strut septoplasty was performed, and the results of the applied methods to correct the crooked nose were evaluated and classified. It was noticed that more than one procedure was applied to each case: (1) double-side lateral osteotomy (86.6%), (2) wedge bone resection on one side of the osteotomy (7.3%), (3) single-side lateral osteotomy (6%), (4) symmetric spreader grafts (56%), (5) asymmetric spreader grafts (10.6%), (6) shaving of the transverse wing of dorsal septum (8%), (7) correction of deviated dorsal septum (16.3%), (8) displaced anterior nasal spine (12.6%), (9) clocking suture (dorsal septal rotation suture) (9%), (10) dorsal septal scoring and splinting graft (8.3%), and equalizing lateral cruses (12.6%).
CONCLUSIONS
I-shaped and C-shaped crooked nose deformities were mainly detected in crooked nose deformity patients. Correcting the crooked nose, double-side lateral osteotomy, and symmetric spreader grafts were the most applied techniques to correct the crooked nose. Other rhinoplasty techniques were also applied to these patients; more than one technique was needed.
Topics: Male; Female; Humans; Rhinoplasty; Nasal Septum; Retrospective Studies; Nose; Osteotomy; Sutures; Treatment Outcome
PubMed: 37869941
DOI: 10.26355/eurrev_202310_34062 -
Plastic and Reconstructive Surgery Nov 2023Dorsal reduction and reshaping is an essential part of many rhinoplasty procedures. The steps of component dorsal reduction have been well established. The authors...
Dorsal reduction and reshaping is an essential part of many rhinoplasty procedures. The steps of component dorsal reduction have been well established. The authors describe refinement of the dorsal reshaping process to improve the quality and consistency of results.
Topics: Humans; Rhinoplasty; Esthetics; Nasal Septum
PubMed: 36728200
DOI: 10.1097/PRS.0000000000010215 -
IBRO Neuroscience Reports Dec 2023There is growing evidence that the hippocampus comprises diverse neural circuits that exhibit longitudinal variation in their properties, however, the intermediate...
There is growing evidence that the hippocampus comprises diverse neural circuits that exhibit longitudinal variation in their properties, however, the intermediate region of the hippocampus has received comparatively little attention. Therefore, this study was designed to compared short- and long-term synaptic plasticity between the dorsal and intermediate regions of the hippocampus in normal and PTZ-kindled rats. Short-term plasticity was assessed by measuring the ratio of field excitatory postsynaptic potentials' (fEPSPs) slope in response to paired-pulse stimulation at three different inter-pulse intervals (20, 80, and 160 ms), while long-term plasticity was assessed using primed burst stimulation (PBS). The results showed that the basal synaptic strength differed between the dorsal and intermediate regions of the hippocampus in both control and kindled rats. In the control group, paired-pulse stimulation of Schaffer collaterals resulted in a significantly lower fEPSP slope in the intermediate part of the hippocampus compared to the dorsal region. Additionally, the magnitude of long-term potentiation (LTP) was significantly lower in the intermediate part of the hippocampus compared to the dorsal region. In PTZ-kindled rats, both short-term facilitation and long-term potentiation were impaired in both regions of the hippocampus. Interestingly, there was no significant difference in synaptic plasticity between the dorsal and intermediate regions in PTZ-kindled rats, despite impairments in both regions. This suggests that seizures eliminate the regional difference between the dorsal and intermediate parts of the hippocampus, resulting in similar electrophysiological activity in both regions in kindled animals. Future studies should consider this when investigating the responses of the dorsal and intermediate regions of the hippocampus following PTZ kindling.
PubMed: 37841086
DOI: 10.1016/j.ibneur.2023.09.010 -
Brain : a Journal of Neurology Feb 2024The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) is a neurodegenerative syndrome primarily defined by the presence of apraxia of speech (AoS)...
The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) is a neurodegenerative syndrome primarily defined by the presence of apraxia of speech (AoS) and/or expressive agrammatism. In addition, many patients exhibit dysarthria and/or receptive agrammatism. This leads to substantial phenotypic variation within the speech-language domain across individuals and time, in terms of both the specific combination of symptoms as well as their severity. How to resolve such phenotypic heterogeneity in nfvPPA is a matter of debate. 'Splitting' views propose separate clinical entities: 'primary progressive apraxia of speech' when AoS occurs in the absence of expressive agrammatism, 'progressive agrammatic aphasia' (PAA) in the opposite case, and 'AOS + PAA' when mixed motor speech and language symptoms are clearly present. While therapeutic interventions typically vary depending on the predominant symptom (e.g. AoS versus expressive agrammatism), the existence of behavioural, anatomical and pathological overlap across these phenotypes argues against drawing such clear-cut boundaries. In the current study, we contribute to this debate by mapping behaviour to brain in a large, prospective cohort of well characterized patients with nfvPPA (n = 104). We sought to advance scientific understanding of nfvPPA and the neural basis of speech-language by uncovering where in the brain the degree of MRI-based atrophy is associated with inter-patient variability in the presence and severity of AoS, dysarthria, expressive agrammatism or receptive agrammatism. Our cross-sectional examination of brain-behaviour relationships revealed three main observations. First, we found that the neural correlates of AoS and expressive agrammatism in nfvPPA lie side by side in the left posterior inferior frontal lobe, explaining their behavioural dissociation/association in previous reports. Second, we identified a 'left-right' and 'ventral-dorsal' neuroanatomical distinction between AoS versus dysarthria, highlighting (i) that dysarthria, but not AoS, is significantly influenced by tissue loss in right-hemisphere motor-speech regions; and (ii) that, within the left hemisphere, dysarthria and AoS map onto dorsally versus ventrally located motor-speech regions, respectively. Third, we confirmed that, within the large-scale grammar network, left frontal tissue loss is preferentially involved in expressive agrammatism and left temporal tissue loss in receptive agrammatism. Our findings thus contribute to define the function and location of the epicentres within the large-scale neural networks vulnerable to neurodegenerative changes in nfvPPA. We propose that nfvPPA be redefined as an umbrella term subsuming a spectrum of speech and/or language phenotypes that are closely linked by the underlying neuroanatomy and neuropathology.
Topics: Humans; Aphasia, Broca; Prospective Studies; Dysarthria; Speech; Cross-Sectional Studies; Apraxias; Aphasia, Primary Progressive; Primary Progressive Nonfluent Aphasia
PubMed: 37769652
DOI: 10.1093/brain/awad327 -
Nature Communications May 2024Serotonin is a neuromodulator that affects multiple behavioral and cognitive functions. Nonetheless, how serotonin causes such a variety of effects via brain-wide...
Serotonin is a neuromodulator that affects multiple behavioral and cognitive functions. Nonetheless, how serotonin causes such a variety of effects via brain-wide projections and various receptors remains unclear. Here we measured brain-wide responses to optogenetic stimulation of serotonin neurons in the dorsal raphe nucleus (DRN) of the male mouse brain using functional MRI with an 11.7 T scanner and a cryoprobe. Transient activation of DRN serotonin neurons caused brain-wide activation, including the medial prefrontal cortex, the striatum, and the ventral tegmental area. The same stimulation under anesthesia with isoflurane decreased brain-wide activation, including the hippocampal complex. These brain-wide response patterns can be explained by DRN serotonergic projection topography and serotonin receptor expression profiles, with enhanced weights on 5-HT1 receptors. Together, these results provide insight into the DR serotonergic system, which is consistent with recent discoveries of its functions in adaptive behaviors.
Topics: Animals; Optogenetics; Dorsal Raphe Nucleus; Male; Serotonergic Neurons; Mice; Serotonin; Magnetic Resonance Imaging; Prefrontal Cortex; Mice, Inbred C57BL; Brain; Ventral Tegmental Area; Hippocampus; Receptors, Serotonin
PubMed: 38755120
DOI: 10.1038/s41467-024-48489-6