Quantitive studies of the reactions to horizontal angular accelerations in axolotls. II. head-turning reflexes in animals with a supernumerary pair of labyrinths

1977 ◽  
Vol 66 (1) ◽  
pp. 15-31
Author(s):  
K. Brandle
Keyword(s):  
Linear Relationship ◽  
Semicircular Canal ◽  
Time Course ◽  
Reaction Threshold ◽  
Head Turning ◽  
Horizontal Semicircular Canal ◽  
Reference Parameter ◽  
Intensity Functions ◽  
The Relationship ◽  
The Brain

In axolotls (Ambystoma mexicanun) the labyrinths and the associated parts of the medulla were doubled artificially. In these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles. The head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. The form and the time-course of the reactions were almost identical in both groups. Tandem-heads showed a linear relationship between stimulus intensity and reaction strength, parallel to that in normal animals but with a greater reaction for a given stimulus. Consequent to this shift in the relationship, there was a significant decrease in the reaction threshold. The removal of one horizontal semicircular canal in tandem-heads proved that both pairs of labyrinths were functionally connected with the brain. It was suggested that during ontogenesis there exists a kind of specificity in the connexion of vestibular fibres. From the parallel shift of the intensity functions it was concluded that the input from both pairs of labyrinths in tandem-heads is not simply accumulate but compared with a reference parameter, which is also double in tandem-heads.

scholarly journals Aspects of the gorgonopsian paleobiology: insights from the basicranium, occiput, osseous labyrinth and neuroanatomy of the immature gorgonopsian skull of Aloposaurus gracilis (Therapsida: Theriodontia: Gorgonopsia)

2016 ◽  
Author(s):  
Ricardo M Araujo ◽  
Vincent Fernandez ◽  
Michael J Polcyn ◽  
Jörg Fröbisch ◽  
Rui M.S. Martins
Keyword(s):  
Computed Tomography ◽  
Semicircular Canal ◽  
Phase Contrast ◽  
Cranial Nerves ◽  
Brain Anatomy ◽  
Micro Computed Tomography ◽  
Horizontal Semicircular Canal ◽  
Head Posture ◽  
The Past ◽  
The Brain

Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy remains poorly known, and aspects of their brain anatomy, cranial nerves and vasculature, osseous labyrinth persist unknown. By using propagation phase contrast synchrotron micro-computed tomography, we scanned GPIT/RE/7124, a specimen previously reported as Aloposaurus gracilis. We explored the anatomy of the braincase and rendered the anatomy of the various skull cavities. Notably, we found that there is a separate ossification between what was previously referred as the “parasphenoid” and the basioccipital. This element is reinterpreted as a posterior ossification of the basisphenoid, the basi-postsphenoid. Additionally the previously called “parasphenoid” is in fact the co-ossification of the dermal parasphenoid and the endochondral basi-presphenoid. The anatomy of the osseous labyrinth is rendered in detail, revealing a unique discoid morphology of the horizontal semicircular canal, rather than toroidal, probably due to architectural contraints of the ossification of the opisthotic and supraoccipital. In addition, the orientation of the horizontal semicircular canal suggests an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.

scholarly journals Task-dependent modulation of SI physiological responses to targets and distractors

2013 ◽  
Vol 109 (4) ◽  
pp. 1036-1044 ◽  
Author(s):  
Elsie Spingath ◽  
Hyun-Sug Kang ◽  
David T. Blake
Keyword(s):  
Time Course ◽  
Cortical Plasticity ◽  
Task Demands ◽  
Neural Responses ◽  
Task Condition ◽  
Sensory Stimuli ◽  
Cortical Implants ◽  
Physically Identical ◽  
The Relationship ◽  
The Brain

Selective attention experimental designs have shown that neural responses to stimuli in primary somatosensory cortex are stronger when the sensory stimuli are task relevant. Other studies have used animals under no task demands for data collection. The relationship between neural responses in the brain during behavior, and while an animal has no task demands, remains underexplored. We trained two animals to perform somatosensory detection for several weeks, followed by somatosensory discrimination for several weeks. Data in response to physically identical stimuli were collected from cortical implants while the animal was under no task demands before each behavioral session and also during that behavioral session. The Fourier spectra of the field potentials during detection or discrimination compared with the no task condition demonstrated suppression of the somatosensory μ-rhythm that is associated with readiness and anticipation of cognitive use of somatosensory and motor inputs. Responses to the task target were stronger during detection and discrimination than in the no task condition. The amplitude normalized time course of the target evoked response was similar in both cases. Evoked responses to the task distractor were not significantly stronger during behavior than in recordings under no task demands. The normalized time course of the distractor responses showed a suppression that peaks 30–35 ms after the onset of the response. The selectivity of this within trial suppression is the same as the selectivity of enduring suppression evident in studies of sensory cortical plasticity, which suggests the same neural process may be responsible for both.

scholarly journals Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy

2017 ◽  
Author(s):  
Ricardo M Araujo ◽  
Vincent Fernandez ◽  
Michael J Polcyn ◽  
Jörg Fröbisch ◽  
Rui M.S. Martins
Keyword(s):  
Semicircular Canal ◽  
Phase Contrast ◽  
Cranial Nerves ◽  
Detailed Examination ◽  
Micro Computed Tomography ◽  
Horizontal Semicircular Canal ◽  
The Past ◽  
Architectural Constraints ◽  
The Brain ◽  
Immature Specimen

Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro-computed tomography. The lack of fusion between many basicranial and occipital bones in the immature specimen GPIT/RE/7124 allowed us to reconstruct its anatomy and ontogenetic sequence in comparison with the mature GPIT/RE/7119. We examined the braincase and rendered various skull cavities. Notably, there is a separate ossification between what was previously referred to as the “parasphenoid” and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, the “parasphenoid” is a co-ossification of the dermal parasphenoid and the endochondral basipresphenoid. Our detailed examination of the osseous labyrinth reveals a unique discoid, rather than toroidal, morphology of the horizontal semicircular canal that probably results from architectural constraints of the opisthotic and supraoccipital ossifications. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.

scholarly journals Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy

2017 ◽  
Author(s):  
Ricardo M Araujo ◽  
Vincent Fernandez ◽  
Michael J Polcyn ◽  
Jörg Fröbisch ◽  
Rui M.S. Martins
Keyword(s):  
Semicircular Canal ◽  
Phase Contrast ◽  
Cranial Nerves ◽  
Detailed Examination ◽  
Micro Computed Tomography ◽  
Horizontal Semicircular Canal ◽  
The Past ◽  
Architectural Constraints ◽  
The Brain ◽  
Immature Specimen

Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro-computed tomography. The lack of fusion between many basicranial and occipital bones in the immature specimen GPIT/RE/7124 allowed us to reconstruct its anatomy and ontogenetic sequence in comparison with the mature GPIT/RE/7119. We examined the braincase and rendered various skull cavities. Notably, there is a separate ossification between what was previously referred to as the “parasphenoid” and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, the “parasphenoid” is a co-ossification of the dermal parasphenoid and the endochondral basipresphenoid. Our detailed examination of the osseous labyrinth reveals a unique discoid, rather than toroidal, morphology of the horizontal semicircular canal that probably results from architectural constraints of the opisthotic and supraoccipital ossifications. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.

scholarly journals Afferent Responses During Experimentally Induced Semicircular Canalithiasis

2007 ◽  
Vol 97 (3) ◽  
pp. 2355-2363 ◽  
Author(s):  
Suhrud M. Rajguru ◽  
Richard D. Rabbitt
Keyword(s):  
Semicircular Canal ◽  
Time Course ◽  
Discharge Rate ◽  
Initial Increase ◽  
Vestibular Disorder ◽  
Afferent Discharge ◽  
Oyster Toadfish ◽  
Head Rotations ◽  
The Brain

Benign paroxysmal positional vertigo (BPPV) is a common vestibular disorder that results in brief periods of vertigo and nystagmus, when the head is tipped relative to gravity. Symptoms are commonly attributed to the pathological presence of heavy calcium carbonate particles within the lumen of the semicircular canal(s)—a condition termed canalithiasis. In the present work, we induced canalithiasis in an animal model (oyster toadfish, Opsanus tau) by introducing heavy glass microbeads into the lumen of the lateral semicircular canal. Bead movement under the action of gravity and canal afferent nerve discharge were recorded in vivo. When the head was oriented nose-down, beads moved toward the nose and the lateral canal afferent discharge rate increased. Afferents that normally encoded angular velocity during oscillatory head rotations responded with tonic increases in the discharge rate during gravity-dependent bead movement. Other afferents, such as the units that rapidly adapt to a step increase in angular head velocity, responded with an initial increase in discharge rate followed by a period of adaptation. Afferent responses occurred in the complete absence of head movement and quantify the pathological inputs to the brain that arise from canalithiasis. The magnitude and time course of the responses reported here are sufficient to explain the symptoms of BPPV.

scholarly journals Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3119 ◽  
Author(s):  
Ricardo Araújo ◽  
Vincent Fernandez ◽  
Michael J. Polcyn ◽  
Jörg Fröbisch ◽  
Rui M.S. Martins
Keyword(s):  
Semicircular Canal ◽  
Phase Contrast ◽  
Cranial Nerves ◽  
Micro Computed Tomography ◽  
Horizontal Semicircular Canal ◽  
Lack Of Fusion ◽  
The Past ◽  
Architectural Constraints ◽  
The Brain ◽  
Immature Specimen

Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270 Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro-computed tomography. The lack of fusion between many basicranial and occipital bones in GPIT/RE/7124, which is an immature specimen, allowed us to reconstruct its anatomy and ontogenetic sequence, in comparison with the mature GPIT/RE/7119, in great detail. We explored the braincase and rendered various skull cavities. Notably, we found that there is a separate ossification between what was previously referred to as the “parasphenoid” and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, we show that the previously called “parasphenoid” is in fact the co-ossification of the dermal parasphenoid and the endochondral basipresphenoid. In line with previous descriptions, the anatomy of the osseous labyrinth is rendered in detail, revealing a unique discoid morphology of the horizontal semicircular canal, rather than toroidal, probably due to architectural constraints of the ossification of the opisthotic and supraoccipital. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.

scholarly journals A Show of Ewald's Law: I Horizontal Semicircular Canal Benign Paroxysmal Positional Vertigo

2021 ◽  
Vol 12 ◽  
Author(s):  
Xueqing Zhang ◽  
Yanru Bai ◽  
Taisheng Chen ◽  
Wei Wang ◽  
Xi Han ◽  
...  
Keyword(s):  
Semicircular Canal ◽  
Healthy Subjects ◽  
Benign Paroxysmal Positional Vertigo ◽  
Positional Nystagmus ◽  
Head Turning ◽  
Horizontal Semicircular Canal ◽  
Positional Vertigo ◽  
Significant Difference ◽  
Latency Duration ◽  
Paroxysmal Positional Vertigo

Objective: To evaluate horizontal semicircular canal (HSC) effects according to Ewald's law and nystagmus characteristics of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) in the supine roll test.Methods: Patients with HSC-BPPV (n = 72) and healthy subjects (n = 38) were enrolled. Latency, duration, and intensity of nystagmus elicited by supine roll test were recorded using video nystagmography.Results: In patients with HSC-BPPV, horizontal nystagmus could be elicited by right/left head position (positional nystagmus) and during head-turning (head-turning nystagmus), and nystagmus direction was the same as that of head turning. Mean intensity values of head-turning nystagmus in HSC-BPPV patients were (44.70 ± 18.24)°/s and (44.65 ± 19.27)°/s on the affected and unaffected sides, respectively, which was not a significant difference (p = 0.980), while those for positional nystagmus were (40.81 ± 25.56)°/s and (17.69 ± 9.31)°/s (ratio, 2.59 ± 1.98:1), respectively, representing a significant difference (p < 0.0001). There was no positional nystagmus in 49 HSC-BPPV patients after repositioning treatment, nor in the 38 healthy subjects. No significant difference in head-turning nystagmus was detected in HSC-BPPV patients with or without repositioning.Conclusions: The direction and intensity of nystagmus elicited by supine roll test in patients with HSC-BPPV, was broadly consistent with the physiological nystagmus associated with a same HSC with single factor stimulus. Our findings suggest that HSC-BPPV can be a show of Ewald's law in human body.

Morphological Changes in the Brain of Acutely Ill and Weight-Recovered Patients with Anorexia Nervosa

2014 ◽  
Vol 42 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Jochen Seitz ◽  
Katharina Bühren ◽  
Georg G. von Polier ◽  
Nicole Heussen ◽  
Beate Herpertz-Dahlmann ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Cognitive Deficits ◽  
Time Course ◽  
Morphological Changes ◽  
Meta Analysis ◽  
Short Term ◽  
Clinical Prognosis ◽  
Qualitative Review ◽  
Brain Changes ◽  
The Brain

Objective: Acute anorexia nervosa (AN) leads to reduced gray (GM) and white matter (WM) volume in the brain, which however improves again upon restoration of weight. Yet little is known about the extent and clinical correlates of these brain changes, nor do we know much about the time-course and completeness of their recovery. Methods: We conducted a meta-analysis and a qualitative review of all magnetic resonance imaging studies involving volume analyses of the brain in both acute and recovered AN. Results: We identified structural neuroimaging studies with a total of 214 acute AN patients and 177 weight-recovered AN patients. In acute AN, GM was reduced by 5.6% and WM by 3.8% compared to healthy controls (HC). Short-term weight recovery 2–5 months after admission resulted in restitution of about half of the GM aberrations and almost full WM recovery. After 2–8 years of remission GM and WM were nearly normalized, and differences to HC (GM: –1.0%, WM: –0.7%) were no longer significant, although small residual changes could not be ruled out. In the qualitative review some studies found GM volume loss to be associated with cognitive deficits and clinical prognosis. Conclusions: GM and WM were strongly reduced in acute AN. The completeness of brain volume rehabilitation remained equivocal.

Grenzenlose Verantwortung

2010 ◽  
Vol 2010 (1) ◽  
pp. 5-22
Author(s):  
Ralf Becker
Keyword(s):  
Personal Freedom ◽  
The Relationship ◽  
The Brain

The article examines the relationship between freedom, guilt and responsibility in Dostojewski’s and Sartre’s works. Both attribute a great measure of personal freedom to man. Therefore, they do not tolerate excuses. Whoever is free, carries responsibility and gets caught up in guilt. Dostojewski’s focus is mainly on guilt, Sartre’s is on responsibility. They share the conviction that we can delegate responsibility for our actions or our way of living neither to a whole, of which we are a part, like society (the ,milieu'), nor to a part, for which we are the whole, like the ,brain' or the ,genes'. In that sense, Dostojewski’s and Sartre’s attempts at an ethic of responsibility also offer convincing arguments against determinism.

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