OBJECTIVES: Previous studies have revealed inconsistent results on amygdala volume in adult bipolar disorder (BD) patients compared to healthy controls (HC). Since the amygdala encompasses multiple subregions, the subtle volume changes in each amygdala nucleus might have not been fully reflected in the measure of the total amygdala volume, causing discrepant results. Thus, we aimed to investigate volume changes in each amygdala subregion and their association with subtypes of BD, lithium use and clinical status of BD. METHODS: Fifty-five BD patients and 55 HC underwent T1-weighted structural magnetic resonance imaging. We analyzed volumes of the whole amygdala and each amygdala subregion, including the anterior amygdaloid area, cortico-amygdaloid transition area, basal, lateral, accessory basal, central, cortical, medial and paralaminar nuclei using the atlas in the FreeSurfer. The volume difference was analyzed using a one-way analysis of covariance with individual volumes as dependent variables, and age, sex, and total intracranial volume as covariates. RESULTS: The volumes of whole right amygdala and subregions including basal nucleus, accessory basal nucleus, anterior amygdaloid area, and cortico-amygdaloid transition area in the right amygdala of BD patients were significantly smaller for the HC group. No significant volume difference between bipolar I disorder and bipolar II disorder was found after the Bonferroni correction. The trend of larger volume in medial nucleus with lithium treatment was not significant after the Bonferroni correction. No significant correlation between illness duration and amygdala volume, and insignificant negative correlation were found between right central nucleus volume and depression severity. CONCLUSIONS: Significant volume decrements of the whole amygdala, basal nucleus, accessory basal nucleus, anterior amygdaloid area, and cortico-amygdaloid transition area were found in the right hemisphere in adult BD patients, compared to HC group. We postulate that such volume changes are associated with altered functional activity and connectivity of amygdala nuclei in BD.
Adult ; Amygdala ; Basolateral Nuclear Complex ; Bipolar Disorder ; Cerebellar Nuclei ; Corticomedial Nuclear Complex ; Depression ; Humans ; Image Processing, Computer-Assisted ; Lithium ; Magnetic Resonance Imaging

Basolateral Nuclear Complex ; Amygdala ; Neural Pathways

Chronic stress induces changes in neuronal functions in specific brain regions regulating sociability and mood-related behaviors. Recently we reported that stress-induced persistent upregulation of the neuropeptides orexin and melanin-concentrating hormone (MCH) in the basolateral amygdala (BLA) and the resulting activation of orexin receptors or MCH receptors within the BLA produced deficits in sociability and mood-related behaviors. In the present study, we investigated the neural targets that were innervated by BLA neurons containing orexin receptors or MCH receptors. The viral vector system AAV2-CaMKII-ChR2-eYFP was injected into the BLA to trace the axonal tracts of BLA neurons. This axon labeling analysis led us to identify the prelimbic and infralimbic cortices, nucleus accumbens (NAc), dorsal striatum, paraventricular nucleus (PVN), interstitial nucleus of the posterior limb of the anterior commissure, habenula, CA3 pyramidal neurons, central amygdala, and ventral hippocampus as the neuroanatomical sites receiving synaptic inputs of BLA neurons. Focusing on these regions, we then carried out stimulus-dependent c-Fos induction analysis after activating orexin receptors or MCH receptors of BLA neurons. Stereotaxic injection of an orexin receptor agonist or an MCH receptor agonist in the BLA induced c-Fos expression in the NAc, PVN, central amygdala, ventral hippocampus, lateral habenula and lateral hypothalamus, which are all potentially important for depression-related behaviors. Among these neural correlates, the NAc, PVN and central amygdala were strongly activated by stimulation of orexin receptors or MCH receptors in the BLA, whereas other BLA targets were differentially and weakly activated. These results identify a functional connectivity of BLA neurons regulated by orexin and MCH receptor systems in sociability and mood-related behaviors.
Axons ; Basolateral Nuclear Complex* ; Brain ; Central Amygdaloid Nucleus ; Depression ; Extremities ; Habenula ; Hippocampus ; Hypothalamic Area, Lateral ; Neurons* ; Neuropeptides ; Nucleus Accumbens ; Orexin Receptors* ; Paraventricular Hypothalamic Nucleus ; Pyramidal Cells ; Up-Regulation

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

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

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.

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*