Changes of dopamine transporter function in striatum during acute morphine addiction and its abstinence in rhesus monkey / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Although dopamine transporter (DAT) is essential for addiction, the effect of additive drugs on DAT function is still controversial, especially for opiates. We investigated the functional changes of dopamine transporter in striatum of rhesus monkeys during acute morphine injection and its abstinence.</p><p><b>METHODS</b>Four rhesus monkeys, 6 to 9 years old, two male and two female, were examined for 12 days. Single photon emission computed tomography (SPECT) was performed with (99)T(cm)-TRODAT-1 as the radiopharmaceutical dopamine transporter agent during different stages of acute morphine injection and its abstinence. The ratios of SPECT signal between striatum and cerebellum (ST/CB) were calculated.</p><p><b>RESULTS</b>The ST/CB ratio declined significantly on the first day of morphine injection and continued declining with more morphine injections. After abstinence, the ratio increased with time, but was still significantly lower on the 5th day of abstinence than the normal level.</p><p><b>CONCLUSIONS</b>In rhesus monkey, acute morphine injection has both rapid and lasting effects on DAT by downregulating its function. The decline was partially reversible following morphine abstinence. The results suggest that striatum is one effective target of morphine and that the DAT function in striatum is one indicator for morphine addiction.</p>

Auditory evoked potentials recorded in monkeys with hallucinatory-like behaviors induced by bromocriptine / 神经科学通报·英文版

Objective Bromocriptine and other dopamine D2 receptor agonists can affect a range of behaviors in nonhuman primates, particularly those behaviors associated with motor and mental function, such as suppressant behaviors and hallucinatory-like behaviors in monkeys. Besides bromocriptine, the dysfunction of the rapid eye movement sleep (REM) mechanism may also contribute to hallucinations. Dissociation of wakefulness, REM, and non-REM (NREM) can cause a series of psychotic symptoms. Methods We simultaneously recorded auditory evoked potentials (AEP) from five cerebral regions in monkeys during normal and psychotomimetic states to investigate and compare state-dependent changes in AEP. Results Phase reversal of peak-to-baseline amplitude of 250 ms component (PBA250) in dorsolateral prefrontal cortex was common characteristic of hallucinatory-like and REM, and that hallucinatory-like and REM shared the equivalent modulatory orderliness of the PBA250 in dorsolateral prefrontal cortex. This result suggests that hallucinatory-like and REM share an equivalent electrophysiological modulatory in dorsolateral prefrontal cortex. Conclusion These results reveal that emergence of the N250 in dorsolateral prefrontal cortex is an exclusive marker that may help to discern whether hallucinatory-like behaviors is exhibited, which suggests that dorsolateral prefrontal cortex may be the most pivotal region for exhibition of hallucinatory-like behaviors.

Continuous representation of human portraits and natural scenery in human ventral temporal cortex: evidence from functional magnetic resonance imaging / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Functional magnetic resonance imaging (fMRI) has become a powerful tool for tracking human brain activity in vivo. This technique is mainly based on blood oxygenation level dependence (BOLD) contrast. In the present study, we employed this newly developed technique to characterize the neural representations of human portraits and natural sceneries in the human brain.</p><p><b>METHODS</b>Nine subjects were scanned with a 1.5 T magnetic resonance imaging (MRI) scanner using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence while they were visually presented with 3 types of white-black photographs: natural scenery, human portraits, and scrambled nonsense pictures. Multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both human portraits and natural scenery. The relative contributions of each type of stimulus to activation in these regions were examined using linear combinations of a general linear test.</p><p><b>RESULTS</b>Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex. The medial region preferentially responded to natural scenery, whereas the lateral one preferentially responded to the human portraits. The general linear test further revealed a distribution gradient such that a change from portraits to scenes shifted areas of activation from lateral to medial.</p><p><b>CONCLUSIONS</b>The boundary between portrait-associated and scenery-associated areas is not as clear as previously demonstrated. The representations of portraits and scenes in ventral temporal cortex appear to be continuous and overlap.</p>

Specific neural basis of Chinese idioms processing:an event-related functional MRI study / 中华放射学杂志

Objective To address the neural basis of Chinese idioms processing with different kinds of stimuli using an event-related fMRI design.Methods Sixteen native Chinese speakers were asked to perform a semantic decision task during fMRI scanning.Three kinds of stimuli were used: Real idioms (Real-idiom condition);Literally plausible phrases (Pseudo-idiom condition,the last character of a real idiom was replaced by a character with similar meaning);Literally implausible strings (Non-idiom condition,the last character of a real idiom was replaced by a character with unrelated meaning).Reaction time and correct rate were recorded at the same time.Results The error rate was 2.6%,5.2% and 0.9% (F = 3.51,P0.05 )for real idioms,pseudo-idioms and wrong idioms, respectively.Similar neural network was activated in all of the three conditions.However,the right hippocampus was only activated in the real idiom condition,and significant activations were found in anterior portion of left inferior frontal gyrus (BA47)in real-and pseudo-idiom conditions,but not in non-idiom condition.Conclusion The right hippocampus plays a specific role in the particular wording of the Chinese idioms.And the left anterior inferior frontal gyms (BA47)may be engaged in the semantic processing of Chinese idioms.The results support the notion that there were specific neural bases for Chinese idioms processing.