Acetylcholine ; Amygdala ; Cues ; Fear

In this study the quantitative changes of the SP (senile plaque) and NFT (neurofibrillary tangle) in the subnucleus of amygdaloid nucleus were analyzed. All patients (83 cases) were diagnosed clinically and confirmed pathologically as Alzheimer disease. The results were: 1) The SP was most prominenentlv observed in the basomedial sub'nucleus region but NFT was in the lateral subnuclei. 2) There were positive Rank Correlation of pathologic degree between the amygdaloidal subnuclei and neocortex except accessory basal subnuclei. 3)Lateral subnucleus had no Rank Correlation between its SP & NFT.
Alzheimer Disease ; Amygdala* ; Humans ; Neocortex

PURPOSE: To compare T2 relaxation times (T2) in the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex between 1.5T and 3.0T MR imagers. MATERIALS AND METHODS: Twelve healthy volunteers underwent FLAIR and CPMG imaging perpendicular to the hippocampal body at both 3.0T and 1.5T. T2 was measured in the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex. The T2 relaxation time ratios of the cingulate cortex, insular cortex, and amygdaloid body to the hippocampal body were compared between 1.5T and 3.0T. RESULTS: The mean T2 of the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex at 1.5T were 109.5+/-3.1, 117.0+/-7.1, 114.7+/-2.4, and 111.3+/-2.4, respectively; 99.7+/-3.8, 100.7+/-4.3, 97.9+/-3.4, and 96.2+/-2.0, respectively, at 3.0T. Percentage changes of T2 in the cingulate cortex, insular cortex, amygdaloid body, and hippocampal body at 3.0T with respect to those at 1.5T were -8.9%, -13.5%, -14.6%, and -13.5%, respectively. The mean T2 ratios of the cingulate gyrus, insular cortex, and amygdaloid body to the hippocampal body at 1.5T and 3.0T were 0.96 and 1.02 (p=0.003); 1.02 and 1.03 (p>0.05); 0.97 and 0.98 (p>0.05), respectively. CONCLUSION: T2 decrease in the cingulate cortex was less than the amygdaloid body, insular cortex, and hippocampal body at 3.0T. The mean T2 ratio of the cingulate gyrus to the hippocampal body was significantly different between 1.5T and 3.0T.
Amygdala ; Brain ; Gyrus Cinguli ; Hippocampus ; Relaxation

Basolateral Nuclear Complex ; Amygdala ; Neural Pathways

OBJECTIVE: Early neuroimaging studies have demonstrated amygdala hypoactivation in schizophrenia but more recent research based on paradigms with minimal cognitive loads or examining automatic processing has observed amygdala hyperactivation. Hyperactivation was found to be related to affective flattening. In this study, amygdala responsivity to threat-related facial expression was investigated in patients as a function of automatic versus controlled processing and patients' flat affect. METHODS: Functional magnetic resonance imaging was used to measure amygdala activation in 36 patients with schizophrenia and 42 healthy controls. During scanning, a viewing task with masked and unmasked fearful and neutral faces was presented. RESULTS: Patients exhibited increased amygdala response to unmasked fearful faces. With respect to masked fearful faces, no between-group differences emerged for the sample as a whole but a subsample of patients with flat affect showed heightened amygdala activation. The amygdala response to masked fearful faces was positively correlated with the degree of flat affect. Conversely, amygdala response to unmasked fearful faces was negatively correlated to the severity of affective flattening. In patients, amygdala responses to masked and unmasked fearful faces showed an inverse correlation. CONCLUSION: Our findings suggest that amygdala hyperresponsivity to unmasked fearful faces might be a functional characteristic of schizophrenia. Amygdala hyperresponsivity to masked fearful faces might be a specific characteristic of patients with affective flattening. A model of flat affect as a response mechanism to emotional overload is proposed.
Amygdala* ; Facial Expression* ; Humans ; Magnetic Resonance Imaging ; Masks ; Neuroimaging ; Schizophrenia*

To investigate the functions of the amygdala in limbic system, changes in heart rate and body temperature resulting from electrical destructions of amygdala centralis and piriform cortex were observed in a total of 40 rats varying in weight from 180 to 250g with the use of stereotaxic apparatus(Reyniers and Sons). The results were as follows; 1) Bilateral destructions of amygdala centralis revealed a tendency to increased heart rate and decreased rectal temperature. 2) Bilateral destructions of piriform cortex revealed no changes in heart rate and rectal temperature. Therefore, it is assumed that cardiovascular and temperature responses are not significantly resulted from the electrical destructions of amygdala centralis and piriform cortex.
Amygdala ; Animals ; Body Temperature ; Heart Rate ; Limbic System ; Rats

The hypothesis that adverse experience alters the balance of neurotransmitters in the amygdala rendering it hyperresponsive to stress was examined in the present study. Since astrocytes regulate the brain's neurochemical milieu by uptaking neurotransmitters, we have examined these cells in the amygdala of prenatally stressed rats, a model of pathological anxiety. Here we examined morphometric changes on the cell bodies of astrocytes in the amygdala induced by prenatal stress and restraint stress. For this purpose, rats were classified into 4 groups; control group (CON), only restraint stressed (starting on P90 for 3 days) group (CONR), prenatally stressed group (PNS), and prenatally and restraint (on P90 for 3 days) stressed group (PNSR). Astrocytes stained with GFAP immunohistochemistry were counter stained with methylene blue/azure II and were examined using the Neurolucida. The present study showed that prenatal and restraint stress caused the significant increase in the total number and length of the amygdaloid astrocytic processes. In conclusion, astrocytes show structural indices of activation with stress.
Amygdala ; Animals ; Anxiety ; Astrocytes ; Immunohistochemistry ; Neurotransmitter Agents ; Organothiophosphorus Compounds ; Rats

In order to investigate the antiepileptic effects of calcium antagonist, nimodipine, we studied the changes of seizure pattern and electroencephalographic finding of the epileptic rats before and after nimodipine administration which were induced by stereotaxic instillation of penicillin solution into the right amygadala. 40 Sprague-Dowley rats were divided into 2 groups:the control group(n=10) which underwent craniectomy on the biparietal area and was instilled penicillin solution into the right amygdala on the basis of stereotaxic coordinates, and the experimental group(n=30) which was subdivided into 3 subgraups:nimodipine pre-treatment group(n=10), nimodipine 0 minute post-treatment group(n=10) and nimodipine 20 minutes post-treatment group(n=10) depending on the intraperitoneal administration time of nimodipine. The results were as follows; 1) In control group typical epileptiform discharges were noted at 3.4+/-1.9 mm after penicillin instillation and the frequency and amplitude of discharges were 9.8+/-2.2/sec, 25.0+/-3.9mm/50+/-microV. The degree of behavioral seizure was between stage IV and VI. 2) In nimodipine pre-treatment group, there was inhibitory effects of seizure development. The frequency and amplitude were significantly decreased and the degree of behavioral seizure was attenuated in comparison to that of control group. 3) There was no statistical difference in effects of penicillin induced seizure between nimodipine 0 minute, 20 minutes post-treatment and control group. This experiment provided that calcium antagonist showed inhibitory effects on the penicillin-induced epileptic rats, but did not prevent seizure propagation. And calcium currents might play a role to evoke seizure. Therefore calcium antagonist "nimodipine" might be beneficial to the treatment of patients with seizure.
Amygdala ; Animals ; Calcium ; Electroencephalography* ; Humans ; Nimodipine* ; Penicillins ; Rats* ; Seizures*

In order to study the effects of stereotaxic destruction of distinct epileptogenic focus, the amygdala was destroyed with radiofrequency coagulator. A total of twenty Sprague-Dawley rats were divided into two group : the control group which underwent craniectomy on the biparietal area and was instilled crytal penicillin solution into the right amygdala on the basis of stereotaxic coordinates(n=10), and the amygdalectomy group which was performed selective amygdalectomy with radiofrequency coagulator after confirmation of clinical and electroencephalographic epileptic features after proceeding same methods of control group(n=10). The experimental epileptic models in rats were obtained by selective instillation of crystal penicillin solution into the right amygdala. The effects of amygdalectomy were investigated by observation of the changes in behavior and electroencephalographic recordings. The results were as follows ; 1) A typical behavioral seizure was shown in the control group and epilepticform discharge was prominent in crystal penicillin soultion instilled side, but there was no bilateral synchronous epileptic discharges during ictal stages. 2) In comparision to two groups, the severity and the frequency of behavioral seizure were more decreased in the stereotaxic amygdalectomy group. 3) The amygdalectomy group was shwon a significant decrease in amplitude and frequency of spikes, especially during interictal stages, compared to the control group. From the results of electroencephalographic and behavioral analysis, selective amygdalectomy with radiofrequency coagulator seemed to be an effective method to treat the crystal penicillin soulution induced epileptic rats.
Amygdala ; Animals ; Penicillins ; Rats* ; Rats, Sprague-Dawley ; Seizures

OBJECTIVETo investigate the antiepileptic effects of various stimulation modes of low-frequency stimulation(LFS) on the kindling rats.

METHODSStimulating electrodes were implanted in the amygdala and current with constant intensity was applied to evoke kindling-induced seizures. The antiepileptic effect of LFS by open loop stimulation(before kindling), closed loop stimulation(immediately after kindling) and different forms of closed loop stimulation(whole stage after kindling and early stage after kindling) were investigated in amygdala kindled rats.

RESULTSThe closed loop LFS of whole stage after kindling can significantly inhibited seizure stages(P<0.01) and reduced afterdischarge duration(P<0.05). The closed loop LFS of early stage after kindling can significantly suppress the seizure stages, mainly in stages 0-3(P<0.05 or P<0.01). The open loop low-frequency stimulation did not inhibit the seizure stage during kindling acquisition(P>0.05).

CONCLUSIONThe antiepileptic effect of low frequency stimulation may have a mode-dependent effect. It may be helpful for the deep brain stimulation as a promising approach applied to clinical antiepileptic therapy in the future.