GABA concentration is reduced in visual cortex in schizophrenia and correlates with orientation-specific surround suppression.
GABA concentration is reduced in visual cortex in schizophrenia and correlates with orientation-specific surround suppression.
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DOI：
10.1523/jneurosci.6158-09.2010
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发表时间：
2010-03-10
期刊：
影响因子：
--
通讯作者：
Carter CS
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文献类型：
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作者：
Yoon JH;Maddock RJ;Rokem A;Silver MA;Minzenberg MJ;Ragland JD;Carter CS
精神分裂症认知缺陷的神经机制在很大程度上仍然未知。γ-氨基丁酸（GABA）假说提出，神经元GABA浓度和神经传递减少导致精神分裂症的认知障碍。然而，很少有体内研究直接检验了这一假设。我们采用磁共振波谱（MRS）在高场测量13名精神分裂症患者和13名人口统计学匹配的健康对照组的视觉皮层GABA水平。我们发现，精神分裂症组的GABA浓度降低了约10%。我们通过检查视觉皮层GABA水平与方向特异性环绕抑制（OSSS）之间的关系进一步验证了GABA假说，OSSS是一种视觉抑制的行为测量方法，被认为依赖于GABA能突触传递。先前的研究表明，精神分裂症患者的对比辨别能力会降低。对于具有MRS和OSSS数据的受试者（n=16），我们发现这些变量之间存在高度显著的正相关性（r=0.76）。GABA浓度与没有周围环境的刺激的整体对比度辨别性能不相关（r=-0.10）。这些结果表明，精神分裂症受试者的新皮层GABA缺陷导致受损的皮层抑制，视觉皮层中的GABA能突触传递在OSSS中起着关键作用。
The neural mechanisms underlying cognitive deficits in schizophrenia remain largely unknown. The gamma-aminobutyric acid (GABA) hypothesis proposes that reduced neuronal GABA concentration and neurotransmission results in cognitive impairments in schizophrenia. However, few in vivo studies have directly examined this hypothesis. We employed magnetic resonance spectroscopy (MRS) at high field to measure visual cortical GABA levels in 13 subjects with schizophrenia and 13 demographically matched healthy control subjects. We found that the schizophrenia group had an approximately 10% reduction in GABA concentration. We further tested the GABA hypothesis by examining the relationship between visual cortical GABA levels and orientation-specific surround suppression (OSSS), a behavioral measure of visual inhibition thought to be dependent on GABAergic synaptic transmission. Previous work has shown that subjects with schizophrenia exhibit reduced OSSS of contrast discrimination. For subjects with both MRS and OSSS data (n=16), we found a highly significant positive correlation (r=0.76) between these variables. GABA concentration was not correlated with overall contrast discrimination performance for stimuli without a surround (r=-0.10). These results suggest that a neocortical GABA deficit in subjects with schizophrenia leads to impaired cortical inhibition and that GABAergic synaptic transmission in visual cortex plays a critical role in OSSS.