AIMTo research the influence of noxious stimuli on the electric activities of pain-related neurons in several subnuclei of Amygdaloid Nucleus in rats.

METHODSTrains of the electric impulses applied to the sciatic nerve were used as noxious stimuli. The discharges of neurons were channeled off by glass microelectrode.

RESULTSPain-related neurons existed in several subnuclei of Amygdaloid Nucleus. When the noxious stimuli were administered the frequency of discharges of pain-excited neurons (PEN) was increased while the frequency of pain-inhibited neurons (PIN) was decreased to the lowest level. The electric activities of PEN and PIN were matched with each other. Intraperitoneal injection of morphine (10 mg/kg) antagonized the effects of noxious stimuli on the pain-related neurons.

CONCLUSIONSeveral subnuclei of Amygdaloid Nucleus play an essential role in perceiving, integrating and transmitting the pain impulses. They are a part of the central nervous system in which pain information is controlled and managed.

Amygdala ; physiology ; Animals ; Electrophysiology ; Neurons ; physiology ; Nociceptors ; physiology ; Rats ; Rats, Wistar

Integrating multisensory inputs to generate accurate perception and guide behavior is among the most critical functions of the brain. Subcortical regions such as the amygdala are involved in sensory processing including vision and audition, yet their roles in multisensory integration remain unclear. In this study, we systematically investigated the function of neurons in the amygdala and adjacent regions in integrating audiovisual sensory inputs using a semi-chronic multi-electrode array and multiple combinations of audiovisual stimuli. From a sample of 332 neurons, we showed the diverse response patterns to audiovisual stimuli and the neural characteristics of bimodal over unimodal modulation, which could be classified into four types with differentiated regional origins. Using the hierarchical clustering method, neurons were further clustered into five groups and associated with different integrating functions and sub-regions. Finally, regions distinguishing congruent and incongruent bimodal sensory inputs were identified. Overall, visual processing dominates audiovisual integration in the amygdala and adjacent regions. Our findings shed new light on the neural mechanisms of multisensory integration in the primate brain.
Animals ; Macaca ; Acoustic Stimulation ; Auditory Perception/physiology* ; Visual Perception/physiology* ; Amygdala/physiology* ; Photic Stimulation

AIMTo investigate whether if the Habenula is the main relay involved in the vasopressor effect induced by the stimulus of insular cortex, central-, lateral amygdaloid nucleus respectively.

METHODSElectrostimulation of the nuclei mention above respectively, and microinjection of lidocaine into Habenula unilaterally and bilaterally.

RESULTSWhen INS or CeA was stimulated, inducing an obvious increase of blood pressure. To stimulate INS or CeA after microinjecting lidocaine into Hb 5 minutes, the amplitudes of the vasopressor responses were decreased significantly, and the decrease of the bilaterally was larger (decreased value: 41.7% in INS, 46.1% in CeA) than that of unilaterally (decreased value: 36.9% in INS, 39.6% in CeA).

CONCLUSIONHabenula is one of the main relays involved in the vasopressor effects induced by the stimulus of insular cortex, central-, lateral amygdaloid nucleus.

Amygdala ; physiology ; Animals ; Blood Pressure ; physiology ; Cerebral Cortex ; physiology ; Electric Stimulation ; Habenula ; physiology ; Neural Pathways ; physiology ; Rats ; Rats, Wistar

Although a great number of studies have investigated the changes of resting-state functional connectivity (rsFC) in patients with mental disorders, such as depression and schizophrenia etc, little is known how stable the changes are, and whether temporal sad or happy mood can modulate the intrinsic rsFC. In our experiments, happy and sad video clips were used to induce temporally happy and sad mood states in 20 healthy young adults. We collected functional magnetic resonance imaging (fMRI) data while participants were watching happy or sad video clips, which were administrated in two consecutive days. Seed-based functional connectivity analyses were conducted using the anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), and amygdala as seeds to investigate neural network related to executive function, attention, and emotion. We also investigated the association of the rsFC changes with emotional arousability level to understand individual differences. There is significantly stronger functional connectivity between the left DLPFC and posterior cingulate cortex (PCC) under sad mood than that under happy mood. The increased connectivity strength was positively correlated with subjects' emotional arousability. The increased positive correlation between the left DLPFC and PCC under sad relative to happy mood might reflect an increased processing of negative emotion-relevant stimuli. The easier one was induced by strong negative emotion (higher emotional arousability), the greater the left DLPFC-PCC connectivity was indicated, the greater the instability of the intrinsic rsFC was shown.
Adult ; Affect ; Amygdala ; physiology ; Attention ; Gyrus Cinguli ; physiology ; Humans ; Magnetic Resonance Imaging ; Prefrontal Cortex ; physiology ; Young Adult

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

To study the effects of estrogen on the contents of dopamine (DA) and its metabolites in the amygdala (Amy) and striatum (Str) of rats, high performance liquid chromatography (HPLC) was used to measure the contents of DA and its metabolites in untreated ovariectomized (OVX) rats and OVX rats treated with estrogen. The contents of DA and its metabolites in Amy but not Str were significantly higher when the OVX rats were treated with a high dose of estradiol benzoate (EB). The turnover rate of DA in Amy of the OVX rats was lower than that of normal and EB-treated OVX rats. The turnover rate of DA in Amy was about twice as high as in the Str, while the content of DA in Amy was only one-sixth of that in the Str. The results obtained imply that serum concentration of estrogen is one of the important factors which affect the DA metabolism and content in the Amy of female rats, while the Str is not influenced by estrogen.
Amygdala ; metabolism ; Animals ; Corpus Striatum ; metabolism ; Dopamine ; metabolism ; Estrogens ; blood ; physiology ; Female ; Rats ; Rats, Wistar

OBJECTIVETo investigate the difference in the brain activation patterns of males and females during video sexual stimulation by functional magnetic resonance imaging (fMRI).

METHODSThe participants were 20 adult males and 20 adult females, all healthy, right-handed, and with no history of sexual function disorder and physical, psychiatric or neurological diseases. Blood-oxygen-level-dependent fMRI was performed using a 1.5 T MR scanner. Three-dimensional anatomical image of the entire brain were obtained by using a T1-weighted three-dimensional anatomical image spoiled gradient echo pulse sequence. Each person was shown neutral and erotic video sequences for 60 s each in a block-study fashion, i.e. neutral scenes--erotic scenes--neutral scenes, and so on. The total scanning time was approximately 7 minutes, with a 12 s interval between two subsequent video sequences in order to avoid any overlapping between erotic and neutral information.

RESULTSThe video sexual stimulation produced different results in the men and women. The females showed activation both in the left and the right amygdala, greater in the former than in the latter ([220.52 +/- 17.09] mm3 vs. [155.45 +/- 18.34] mm3, P < 0.05), but in the males only the left amygdala was activated. The males showed greater brain activation than the females in the left anterior cingulate gyrus ([420.75 +/- 19.37] mm3 vs. [310.67 +/- 10.53] mm3, P < 0.05), but less than the females in the splenium of the corpus callosum ([363.32 +/- 13.30] mm3 vs. [473.45 +/- 14.92] mm3, P < 0.01).

CONCLUSIONBrain activation patterns of males and females during video sexual stimulation are different, underlying which is presumably the difference in both the structure and function of the brain between men and women.

Adult ; Amygdala ; physiology ; Brain ; physiology ; Brain Mapping ; Coitus ; physiology ; Corpus Callosum ; physiology ; Female ; Gyrus Cinguli ; physiology ; Humans ; Magnetic Resonance Imaging ; Male ; Sex Factors

AIMTo investigate the inhibitory effect of the deep peroneal nerve (DPN) on the cardiovascular responses induced by excitation of the paraventricular nucleus of hypothalamus (PVN) and the role of central nucleus of amygdala (CeA) in this effect.

METHODSCeA was injected by L-glutamate or Kainic acid (KA). The femoral arterial pressure, mean arterial pressure (MAP), electrocardiogram (ECG) and heart rate (HR) of SD rats were recorded while PVN or DPN was electrically stimulated.

RESULTSIt showed that MAP increased when PVN was activated by electrical stimulation. Stimulating contralateral DPN inhibited this pressor response. Ten minutes after microinjection of KA(0.02 mol/L, 100 nl) into ipsilateral CeA, MAP increased for (13.8 +/- 3.2) mmHg when PVN was stimulated. Microinjection of KA into CeA could not only reduce the pressor response elicited by stimulation of PVN for (6.6 +/- 1.6) mmHg (P < 0.05), but also the inhibitory effect of DPN from 51.5% to 32.0% .

CONCLUSIONThe results suggest that central nucleus of amygdala partly mediate the central pressor response induced by stimulation of PVN. The neurons in central nucleus of amygdala are involved in the inhibitory effect of DPN on the above pressor response.

Afferent Pathways ; Amygdala ; physiology ; Animals ; Blood Pressure ; Central Nervous System ; physiology ; Hypothalamus ; physiology ; Paraventricular Hypothalamic Nucleus ; physiology ; Peroneal Nerve ; physiology ; Rats ; Rats, Sprague-Dawley

We present here a case in which functional MR imaging (fMRI) was done for a patient who developed retrograde psychogenic amnesia for a four year period of her life history after a severe stressful event. We performed the fMRI study for a face recognition task using stimulation with three kinds of face photographs: recognizable familiar faces, unrecognizable friends' faces due to the psychogenic amnesia, and unfamiliar control faces. Different activation patterns between the recognizable faces and unrecognizable faces were found in the limbic area, and especially in the amygdala and hippocampus.
*Stress Disorders, Post-Traumatic ; *Magnetic Resonance Imaging ; Humans ; Hippocampus/physiology ; Female ; Amygdala/physiology ; Amnesia, Retrograde/*diagnosis/*etiology ; Adult