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Journal of Neurology Dec 2022Vertical pendular nystagmus (PN) rarely occurs with acute pontine lesions. To hypothesize a pathophysiology for acute vertical PN, we analyzed the clinical... (Review)
Review
Vertical pendular nystagmus (PN) rarely occurs with acute pontine lesions. To hypothesize a pathophysiology for acute vertical PN, we analyzed the clinical characteristics and quantitative eye-movement recordings of one new case with acute vertical PN and an additional 11 patients from the literature. Most patients had extensive pontine lesions causing either the locked-in syndrome or unresponsiveness, but two conscious patients had focal lesions restricted to the paramedian caudal pontine tegmentum. All patients presented a complete or partial horizontal gaze palsy, and about half showed ocular bobbing before or during the appearance of vertical PN. The vertical oscillations were conjugate at a frequency of 1-5 Hz, and the amplitudes were variable, ranging from 0.2° to 40°. The peak velocities were asymmetric in some patients, faster with downward movements. About half of the patients developed palatal tremor several weeks or months after presenting with acute vertical PN. Based on the location of the lesions and results of eye-movement recordings, we suggest two possible mechanisms for acute vertical PN; oscillations originating in the inferior olives due to disruption of the central tegmental tract or low-velocity saccadic oscillations caused by omnipause neuron damage.
Topics: Humans; Nystagmus, Pathologic; Eye Movements; Pons; Ocular Motility Disorders; Movement
PubMed: 35904591
DOI: 10.1007/s00415-022-11314-5 -
Acta Neurobiologiae Experimentalis 1996The cat's pons was isolated by two brainstem transections, at the junction of medulla and pons and at the junction of pons and midbrain. In the deafferented pons the EEG...
The cat's pons was isolated by two brainstem transections, at the junction of medulla and pons and at the junction of pons and midbrain. In the deafferented pons the EEG activity was virtually absent, whereas the spatial density of active units and the rate of their spontaneous spike activity were at a high level. In the pons of control preparations with brainstem transected only at the ponto-midbrain junction the EEG activity was present, while the single-unit activity was such as in the isolated pons. The electrical activity of the isolated pons was similar to that previously described in the cat's isolated midbrain. The discrepancy between EEG and single-unit activity suggests that in the deafferented pons or midbrain many neurones are asynchronously autoactive. Also, these results show that a flat EEG record is not necessarily a sign of absence of the neural activity and neural death.
Topics: Animals; Cats; Electroencephalography; Electrophysiology; In Vitro Techniques; Pons
PubMed: 8917897
DOI: 10.55782/ane-1996-1172 -
Brain Research Bulletin 1994This article reviews evidence for a direct noradrenergic projection from the dorsolateral pontine tegmentum (DLPT) to spinal motoneurons. The existence of this direct... (Review)
Review
This article reviews evidence for a direct noradrenergic projection from the dorsolateral pontine tegmentum (DLPT) to spinal motoneurons. The existence of this direct pathway was first inferred by the observation that antidromically evoked responses occur in single cells in the locus coeruleus (LC), a region within the DLPT, following electrical stimulation of the ventral horn of the lumbar spinal cord of the cat. We subsequently confirmed that there is a direct noradrenergic pathway from the LC and adjacent regions of the DLPT to the lumbar ventral horn using anatomical studies that combined retrograde tracing with immunohistochemical identification of neurotransmitters. These anatomical studies further revealed that many of the noradrenergic neurons in the LC and adjacent regions of the DLPT of the cat that send projections to the spinal cord ventral horn also contain colocalized glutamate (Glu) or enkephalin (ENK). Recent studies from our laboratory suggest that Glu and ENK may function as cotransmitters with norepinephrine (NE) in the descending pathway from the DLPT. Electrical stimulation of the LC evokes a depolarizing response in spinal motoneurons that is only partially blocked by alpha 1 adrenergic antagonists. In addition, NE mimicks only the slowly developing and not the fast component of LC-evoked depolarization. Furthermore, the depolarization evoked by LC stimulation is accompanied by a decrease in membrane resistance, whereas that evoked by NE is accompanied by an increased resistance. That Glu may be a second neurotransmitter involved in LC excitation of motoneurons is supported by our observation that the excitatory response evoked in spinal cord ventral roots by electrical stimulation of the LC is attenuated by a non-N-methyl-D-aspartate glutamatergic antagonist. ENK may participate as a cotransmitter with NE to mediate LC effects on lumbar monosynaptic reflex (MSR) amplitude. Electrical stimulation of the LC has a biphasic effect on MSR amplitude, facilitation followed by inhibition. Adrenergic antagonists block only the facilitator effect of LC stimulation on MSR amplitude, whereas the ENK antagonist naloxone reverses the inhibition. The chemical heterogeneity of the cat DLPT system and the differential responses of motoneurons to the individual cotransmitters help to explain the diversity of postsynaptic potentials that occur following LC stimuli.
Topics: Animals; Cats; Locus Coeruleus; Motor Neurons; Neural Pathways; Neurotransmitter Agents; Pons
PubMed: 7859099
DOI: 10.1016/0361-9230(94)90155-4 -
Neurosurgery Mar 2008COSTANZO VAROLIO (CONSTANTIUS Varolius) (1543-1575) was born in Bologna and died in Rome. This professor of anatomy and papal physician was the first to examine the...
COSTANZO VAROLIO (CONSTANTIUS Varolius) (1543-1575) was born in Bologna and died in Rome. This professor of anatomy and papal physician was the first to examine the brain from its base up, in contrast with previous dissections of this organ performed from the top down. Varolio was the first to describe many structures, including the pons, which is still known today as the pons Varolli. Varolio was a pupil to the well-known anatomist Aranzio, who was in turn a pupil of Vesalius. Our current understanding of the nervous system is based on the early anatomic descriptions and depictions by such individuals as Varolio.
Topics: History, 16th Century; Humans; Italy; Neuroanatomy; Pons
PubMed: 18425020
DOI: 10.1227/01.neu.0000317323.63859.2a -
Journal of Neurophysiology Jun 19881. Behavioral studies have shown that chronic decerebrate rats retain the capacity to react appropriately to gustatory stimuli (12), but do not form taste-illness... (Comparative Study)
Comparative Study
1. Behavioral studies have shown that chronic decerebrate rats retain the capacity to react appropriately to gustatory stimuli (12), but do not form taste-illness associations (13). Little is known, however, about the effects of decerebration on the processing of gustatory information. The present experiment was designed to investigate this issue in the parabrachial nucleus of the pons (PbN). 2. Rats were decerebrated at the supracollicular level under ketamine and ether anesthesia and were prepared for electrical recording in the PbN. Thereafter, animals were maintained under Flaxedil, and wound edges were frequently treated with lidocaine. Heart rate, core temperature, and CO2 were monitored throughout each experiment. Control subjects were treated identically, except that they were not decerebrated. 3. Sapid solutions of NaCl (0.1 M), HCl (0.01 M), sucrose (0.5 M), saccharin sodium (0.004 M), and quinine HCl (.01 M) were used as taste stimuli. After a 10-s base line, each stimulus was bathed over the tongue for 10 s followed by a 10-s wait and a 20-s rinse of distilled water. The intertrial interval was at least 2 min. 4. Gustatory responses from 32 parabrachial units in 13 decerebrate rats were recorded. These were compared with responses in 31 units from the PbN of 16 intact rats. 5. Analysis of response profiles of PbN units in decerebrate rats showed that these units produced smaller responses to NaCl and HCl and larger responses to saccharin sodium compared with units in intact rats. 6. Despite changes in response magnitude, the temporal patterns of response (phasic-tonic relationships) were not different in PbN units in decerebrate rats compared with controls. Differences in the length of responses were, however, apparent. Responses to saccharin sodium were longer, response to NaCl, HCl and sucrose were shorter, and responses to quinine HCl were unchanged. 7. Results of a multidimensional scaling analysis of the response profiles across units showed that "taste spaces" for decerebrate and intact rats were similar. Units in each group were meaningfully placed near stimuli that evoked the best response in a given unit. Units that did not respond well to any stimulus were placed close together regardless of their best stimulus in both taste spaces. 8. Responses to the termination of the taste stimulus (OFF-responses) were observed in PbN units in the decerebrate rat but not in units from the intact rat. Twenty-one OFF-responses were recorded in 14 units; 6 of these occurred in the absence of a response to the stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Decerebrate State; Neurons; Physical Stimulation; Pons; Rats; Reaction Time; Taste
PubMed: 3404209
DOI: 10.1152/jn.1988.59.6.1871 -
Journal of Applied Physiology... Feb 1997
Topics: Animals; Pons; Rats; Respiration
PubMed: 9049712
DOI: 10.1152/jappl.1997.82.2.375 -
Deutsches Arzteblatt International Oct 2021
Topics: Humans; Magnetic Resonance Imaging; Pons; Syndrome
PubMed: 35086637
DOI: 10.3238/arztebl.m2021.0080 -
Brain Research Jul 1976Third-order neurons from the pontine taste area (PTA) were analyzed in accordance with the across-fiber pattern theory of gustatory neural coding. Single neuron...
Third-order neurons from the pontine taste area (PTA) were analyzed in accordance with the across-fiber pattern theory of gustatory neural coding. Single neuron responses, evoked by chemical stimulation of the tongue, were recorded from the PTA of acute Nembutalized rats. They reveal that PTA neurons are broadly sensitive to stimuli representing the 4 putative basic taste qualities. Of 35 neurons, 33 responded to at least 3 of the 4 quality classes. Time course analyses indicate that stimuli which are shown to be alike in behavioral studies exhibit similar temporal response sequences. Correlations between all possible pairs of response patterns indicate that like-tasting chemicals elicit similar profiles of activity across the neural population. A multidimensional analysis indicates that three underlying physico-chemical dimensions (as yet undefined) bear upon the neural responses. In certain of their response properties, PTA neurons are like those of the (second-order) solitary nucleus; in other respects they auger the characteristics seen in the (fourth-order) thalamic neurons. It is concluded that the PTA is functionally as well as anatomically intermediate between the solitary nucleus and thalamus in the taste processing chain.
Topics: Animals; Discrimination, Psychological; Evoked Potentials; Male; Neural Inhibition; Neurons; Pons; Rats; Reaction Time; Taste; Temperature; Time Factors
PubMed: 938944
DOI: 10.1016/0006-8993(76)90403-0 -
Respiratory Physiology & Neurobiology Nov 2004We have proposed a "switching concept" for the neurogenesis of ventilatory activity. Eupnea reflects the output of a pontomedullary neuronal circuit, whereas gasping is... (Review)
Review
We have proposed a "switching concept" for the neurogenesis of ventilatory activity. Eupnea reflects the output of a pontomedullary neuronal circuit, whereas gasping is generated by medullary pacemaker mechanisms. Pontile mechanisms, then, are hypothesized to play a fundamental role in the neurogenesis of eupnea. If pontile mechanisms do play such a critical role, several criteria must be fulfilled. First, perturbations of pontile regions must alter eupnea under all experimental conditions. Second, neuronal activities that are consistent with generating the eupneic rhythm must be recorded in pons. Finally, medullary mechanisms alone cannot fully explain the neurogenesis of eupnea. Evidence from previous studies that support the validity of these criteria is presented herein. We conclude that pontile mechanisms play a critical role in the neurogenesis of eupnea.
Topics: Animals; Apnea; Decerebrate State; Medulla Oblongata; Nerve Net; Neurons; Periodicity; Phrenic Nerve; Pons; Respiration; Respiratory System
PubMed: 15519564
DOI: 10.1016/j.resp.2004.05.010 -
Brain Research Bulletin Sep 1989Sex-related and pregnancy-related variations in taste preferences have long been known to exist in humans as well as animals. However, the neurophysiological... (Comparative Study)
Comparative Study
Sex-related and pregnancy-related variations in taste preferences have long been known to exist in humans as well as animals. However, the neurophysiological underpinnings of these variations have not yet been described. In an effort to discover whether differences in hormonal state are reflected in the neural processing within the gustatory system, electrophysiological responses to representatives of the 4 basic taste qualities were recorded in the parabrachial nucleus of the pons (PbN) of male, diestrous female and pregnant rats. Results revealed that PbN units in female and pregnant rats showed larger responses to sweet stimuli than units in male rats. Also, a greater proportion of units in female and pregnant rats were classified as sweet-best compared with units in males. This result may correlate with the greater preference for sweet stimuli in female rats compared with males that has been reported in the behavioral literature. Analysis of response profiles with multidimensional scaling techniques showed that units that responded best to a given stimulus were placed near that stimulus for units from males, but not for units from female and pregnant rats. Hierarchical cluster analysis of response profiles suggested 3 clusters of units within each group of PbN units. Response profiles within clusters showed different types of units in male, female and pregnant rats. Collectively, these data suggest that ovarian hormones may act to alter the central processing of gustatory information. Evidence for both activational and organizational effects of ovarian hormones on the gustatory system is discussed.
Topics: Action Potentials; Animals; Female; Food Preferences; Male; Mathematics; Pons; Pregnancy; Pregnancy, Animal; Rats; Saccharin; Sex Factors; Sucrose; Taste
PubMed: 2819479
DOI: 10.1016/0361-9230(89)90151-2