In the present study, the responses of inhibitory gustatory neurons in the parabrachial nucleus (PBN) to four basic taste stimuli NaCl, HCl, quinine HCl (QHCl) and sucrose were examined using single-unit recording technique in anesthetized rats. A total of 18 inhibitory taste neurons in the PBN were obtained. Spontaneous firing rates of these inhibitory neurons were 0.2-5.5 Hz with mean firing rate of (2.15+/-0.31) Hz. Most of the neurons responded to more than one of the basic taste qualities. The inhibitory responses to taste occurred quickly and lasted 5-80 s in different PBN neurons. According to the responsive characteristics to the four basic taste stimuli, the neurons could be classified as NaCl-best (n=8), HCl-best (n=3), QHCl-best (n=3), and sucrose-best (n=4). The breadth of tuning of NaCl-best neurons was the highest (0.945). Inhibitory responsive neurons had feeble discrimination among sapid stimuli or aversive stimuli. These results suggest that there exist inhibitory taste neurons in the PBN. These neurons may play some useful roles in precise transmission of taste information and the taste coding for hedonic and aversive tastes.
Animals ; Male ; Neural Inhibition ; physiology ; Neurons ; physiology ; Pons ; physiology ; Rats ; Rats, Sprague-Dawley ; Taste ; physiology

The pedunculopontine nucleus (PPN) is located in the dorso-lateral part of the ponto-mesencephalic tegmentum. The PPN is composed of two groups of neurons: one containing acetylcholine, and the other containing non-cholinergic neurotransmitters (GABA, glutamate). The PPN is connected reciprocally with the limbic system, the basal ganglia nuclei (globus pallidus, substantia nigra, subthalamic nucleus), and the brainstem reticular formation. The caudally directed corticolimbic-ventral striatal-ventral pallidal-PPN-pontomedullary reticular nuclei-spinal cord pathway seems to be involved in the initiation, acceleration, deceleration, and termination of locomotion. This pathway is under the control of the deep cerebellar and basal ganglia nuclei at the level of the PPN, particularly via potent inputs from the medial globus pallidus, substantia nigra pars reticulata and subthalamic nucleus. The PPN sends profuse ascending cholinergic efferent fibers to almost all the thalamic nuclei, to mediate phasic events in rapid-eye-movement sleep. Experimental evidence suggests that the PPN, along with other brain stem nuclei, is also involved in anti-nociception and startle reactions. In idiopathic Parkinson's disease (IPD) and parkinson plus syndrome, overactive pallidal and nigral inhibitory inputs to the PPN may cause sequential occurrences of PPN hypofunction, decreased excitatory PPN input to the substantia nigra, and aggravation of striatal dopamine deficiency. In addition, neuronal loss in the PPN itself may cause dopamine-r esistant parkinsonian deficits, including gait disorders, postural instability and sleep disturbances. In patients with IPD, such deficits may improve after posteroventral pallidotomy, but not after thalamotomy. One of the possible explanations for such differences is that dopamine-resistant parkinsonian deficits are mediated to the PPN by the descending pallido-PPN inhibitory fibers, which leave the pallido-thalamic pathways before they reach the thalamic targets.
Animal ; Basal Ganglia/cytology ; Human ; Mesencephalon/physiology* ; Mesencephalon/cytology ; Movement Disorders/etiology* ; Pons/physiology* ; Pons/cytology ; Thalamus/cytology

To access the role of the central nucleus of the amygdala (CeA) in the gustatory activity in the pontine parabrachial nucleus (PBN), the responses to four prototypical taste stimuli (NaCl, HCl, QH2SO4 and sucrose) in the PBN were observed before and after bilateral electrolytic lesion of the CeA in the urethane-anesthetized rat. Of 29 neurons, 14 were classified as NaCl-best, 9 as HCl-best, 3 as QH2SO4-best and 3 sucrose-best. After CeA lesions, the response rates to HCl and QH2SO4 were statistically higher across all PBN neurons (P<0.01). According to the best-stimulus category, the effects on the responses to HCl and QH2SO4 were similarly subjected to these modulations in NaCl-best, HCl-best and QH2SO4-best neurons. Correlation analysis indicated that the CeA lesion depressed the effect on the chemical selection between NaCl and QH2SO4. These findings suggest that the CeA plays an important role in the taste coding at the pontine level and it may be involved in mediating the feeding behavior via modulating the gustatory responses.
Amygdala ; injuries ; physiology ; Animals ; Electric Stimulation ; methods ; Female ; Male ; Pons ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley ; Taste ; physiology

AIMTo investigate the effects of central amygdaloid nucleus (CeA) on the evaluation of taste in rats, and explore the mechanisms of the CeA in modulating the feeding behavior.

METHODSBy using two-bottle choice test, we measured the consumption of serials concentrations of NaCl, citric acid (CA), quinine HCl (QHCl) and sucrose in bilateral CeA lesioned rats, and compared the results to those in sham lesioned rats.

RESULTSThe CeA-lesioned rats exhibited a lower preference for NaCl at concentrations of 0.03; 0.1 and 0.3 mol/L, for CA at concentrations of 0.01; 0.1 and 1.0 mmol/L, and for QHCl at 10; 20 and 50 micromol/L, but the preference for serials of concentrations of sucrose are similar between two groups. By comparing the intake of adjacent concentrations of sapid solutions, it indicated that CeA-lesioned rats showed a lower distinction between adjacent concentrations of NaCl, CA and QHCl. However, the total consumption (water and tastants) during all the test sessions was not significantly different between two groups of rats.

CONCLUSIONLesion of CeA decreases the intake of tastants solution, but the effects on different concentrations of solution are different. It suggests that the CeA plays an important role in the normal response to exteroceptive food stimuli through impacting on the assessment of taste and altering the preference threshold of gustatory stimuli.

Amygdala ; physiopathology ; Animals ; Drinking ; Electric Stimulation ; Feeding Behavior ; Male ; Pons ; Rats ; Rats, Sprague-Dawley ; Taste ; physiology

The ventral nucleus of the lateral lemniscus (VNLL) is an important nucleus in the central auditory pathway which connects the lower brainstem and the midbrain inferior colliculus (IC). Previous studies have demonstrated that neurons in the VNLL could respond to sound signal parameters. Frequency tuning curves (FTCs) of VNLL neurons are generally wider than FTCs of IC neurons, suggesting that the VNLL does not enhance abilities of frequency discrimination and coding. Two types of rate-intensity functions (RIFs) are found in the VNLL: monotonic and non-monotonic RIFs. Intensity-tuning of VNLL neurons are affected by the temporal firing patterns during processing and encoding intensity. There are multiple temporal firing patterns in VNLL neurons. Onset pattern has a precise timing characteristic which is well suited to encode temporal features of stimuli, and also very important to animal behavior including bat's echolocation. The VNLL accepts inputs from lower nuclei, uploads glycine inhibitory outputs to IC, and modulates response characteristics generating and acoustic signal processing of IC neurons. Recent research suggests that fast inhibitory projection from the VNLL may delay the first spike latency of IC neurons, and the delayed inhibitory projection from the VNLL may mediate the temporal firing patterns of IC neurons. But how inhibitory inputs from the VNLL integrate in IC, and how inhibitory inputs from the VNLL enhance the ability of detecting sound signal of IC neurons are not very clear and need more direct evidence at the level of neurons. These questions will help further understand the role of upload during IC processes acoustic signal, which are our research target in the future. This article reviews the current literature regarding the roles of the VNLL in sound signal processing and the auditory ascending transmission, including advances in the relevant research in our laboratory.
Acoustic Stimulation ; Animals ; Auditory Pathways ; Chiroptera ; Echolocation ; Neurons ; physiology ; Pons ; cytology

Micturition is a complex process involving the bladder, spinal cord, and the brain. Highly sophisticated central neural program controls bladder function by utilizing multiple brain regions, including pons and suprapontine structures. Periaqueductal grey, insula, anterior cingulate cortex, and medial prefrontal cortex are components of suprapontine micturition centers. Under pathologic conditions such as epilepsy, urinary dysfunction is a frequent symptom and it seems to be associated with increased suprapontine cortical activity. Interestingly, micturition can also trigger seizures known as reflex epilepsy. During voiding behavior, frontotemporal cortical activation has been reported and it may induce reflex seizures. As current researches are only limited to present clinical cases, more rigorous investigations are needed to elucidate biological mechanisms of micturition to advance our knowledge on the process of micturition in physiology and pathology.
Brain ; Epilepsy* ; Epilepsy, Reflex ; Gyrus Cinguli ; Pathology ; Physiology ; Pons ; Prefrontal Cortex ; Reflex ; Seizures ; Spinal Cord ; Urinary Bladder ; Urination*

Circadian clocks are the endogenous oscillators that harmonize a variety of physiological processes within the body. Although many urinary functions exhibit clear daily or circadian variation in diurnal humans and nocturnal rodents, the precise mechanisms of these variations are as yet unclear. In the present study, we demonstrate that Per2 promoter activity clearly oscillates in neonate and adult bladders cultured ex vivo from Per2::Luc knock-in mice. In subsequent experiments, we show that multiple local oscillators are operating in all the bladder tissues (detrusor, sphincter and urothelim) and the lumbar spinal cord (L4-5) but not in the pontine micturition center or the ventrolateral periaqueductal gray of the brain. Accordingly, the water intake and urine volume exhibited daily and circadian variations in young adult wild-type mice but not in Per1-/- Per2-/- mice, suggesting a functional clock-dependent nature of the micturition rhythm. Particularly in PDK mice, the water intake and urinary excretion displayed an arrhythmic pattern under constant darkness, and the amount of water consumed and excreted significantly increased compared with those of WT mice. These results suggest that local circadian clocks reside in three types of bladder tissue and the lumbar spinal cord and may have important roles in the circadian control of micturition function.
Animals ; *Circadian Clocks ; Drinking ; Mice ; Organ Specificity ; Periaqueductal Gray/metabolism/physiology ; Period Circadian Proteins/genetics/*metabolism ; Pons/metabolism/physiology ; Spinal Cord/*metabolism/physiology ; Urinary Bladder/innervation/metabolism/*physiology ; Urination

Taste responses in the parabrachial nucleus (PBN) are significantly affected by stimulation or lesion of the central nucleus of the amygdala (CeA). To examine if the glutamate receptors in the CeA are involved in this modulation, the effects of microinjection of 6-cyano-7-nitro-quinoxaline-2, 3-dione (CNQX), an AMPA receptor antagonist, into the CeA on the activities of PBN taste neurons were observed by using extracellular recording technique. Responses of PBN taste neurons to taste stimuli were observed before and after CNQX administered to the CeA. In general, drug administration produced a time-dependent suppress of the responses in 30% PBN taste neurons, with the firing rates to HCl and QHCl were significantly lowered (P<0.05). According to the best-stimulus category, 40% NaCl-best (6/15), 30% HCl-best (3/10) and 20% QHCl-best (1/5) neurons decreased their responses to at least one basic taste stimulus after CNQX injection. In HCl- and QHCl-best neurons, the main responses were significantly inhibited after drug injections (P<0.01). The correlation coefficient of responses between the NaCl and the other three tastants decreased after drug administration to the CeA. These results suggest that AMPA receptors within the CeA may be involved in the descending modulation in the PBN taste neurons.
6-Cyano-7-nitroquinoxaline-2,3-dione ; pharmacology ; Amygdala ; drug effects ; physiology ; Animals ; Electric Stimulation ; methods ; Evoked Potentials ; physiology ; Male ; Microinjections ; Pons ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA ; antagonists & inhibitors ; Taste ; physiology ; Taste Threshold

The corticospinal tract (CST) is the most important motor pathway in the human brain. Detailed knowledge of CST somatotopy is important in terms of rehabilitative management and invasive procedures for patients with brain injuries. In this study, I conducted a review of nine previous studies of the somatotopical location and arrangement at the brainstem in the human brain. The results of this review indicated that the hand and leg somatotopies of the CST are arranged medio-laterally in the mid to lateral portion of the cerebral peduncle, ventromedial-dorsolaterally in the pontine basis, and medio-laterally in the medullary pyramid. However, few diffusion tensor imaging (DTI) studies have been conducted on this topic, and only nine have been reported: midbrain (2 studies), pons (4 studies), and medulla (1 study). Therefore, further DTI studies should be conducted in order to expand the literature on this topic. In particular, research on midbrain and medulla should be encouraged.
Brain Stem/*anatomy & histology ; Diffusion Tensor Imaging ; Hand/innervation ; Humans ; Leg/innervation ; Medulla Oblongata/anatomy & histology ; Pons/anatomy & histology ; Pyramidal Tracts/*anatomy & histology/physiology ; Tegmentum Mesencephali/anatomy & histology

AIMTo investigate the change of latency and interpeak latency of each component of BAEP (brainstem auditory evoked potential, BAEP) and its correlation with PV/PFV (pontine volume/posterior fossa volume, PV/PFV) ratio in OPCA (olivopontocerebellar atrophy, OPCA).

METHODSWe used Keypoint EMG/EP to determine waves I PL (peak latency, PL), III PL, V PL and I - III IPL (interpeak latency, IPL), III - V IPL, I - V IPL and used 1.5TMR 3D volume rendering software to determine PV (pontine volume, PV), CV(cerebellar volume, CV) and PFV (posterior fossa volume,PFV). Then calculated PV/PFV ratio, CV/PFV ratio and PV/ CV ratio in OPCA group and control group.

RESULTSCompared with control group, in OPCA group wave IIII PL, I - III IPL were significantly elongated (P < 0.05), III - V IPL was significantly shorten (P < 0.05), PV/PFV ratio was significantly decreased (P < 0.01); there was a positive correlation between III-V IPL and PV/PFV ratio (r = 0.83, P < 0.01).

CONCLUSIONIn patients with OPCA, III PL, I - III IPL of BAEP were elongated and III - V IPL of BAEP was shorten. III - V IPL became shorter when the volume of pontine decreased.

Adult ; Case-Control Studies ; Evoked Potentials, Auditory, Brain Stem ; physiology ; Female ; Humans ; Male ; Middle Aged ; Olivopontocerebellar Atrophies ; pathology ; physiopathology ; Pons ; pathology