Major depressive disorder (MDD) is a complex state-dependent psychiatric illness for which biomarkers linking psychophysical, biochemical, and psychopathological changes remain yet elusive, though. Earlier studies demonstrate reduced GABA in lower-order occipital cortex in acute MDD leaving open its validity and significance for higher-order visual perception, though. The goal of our study is to fill that gap by combining psychophysical investigation of visual perception with measurement of GABA concentration in middle temporal visual area (hMT+) in acute depressed MDD. Psychophysically, we observe a highly specific deficit in visual surround motion suppression in a large sample of acute MDD subjects which, importantly, correlates with symptom severity. Both visual deficit and its relation to symptom severity are replicated in the smaller MDD sample that received MRS. Using high-field 7T proton Magnetic resonance spectroscopy (¹H-MRS), acute MDD subjects exhibit decreased GABA concentration in visual MT+ which, unlike in healthy subjects, no longer correlates with their visual motion performance, i.e., impaired SI. In sum, our combined psychophysical-biochemical study demonstrates an important role of reduced occipital GABA for altered visual perception and psychopathological symptoms in acute MDD. Bridging the gap from the biochemical level of occipital GABA over visual-perceptual changes to psychopathological symptoms, our findings point to the importance of the occipital cortex in acute depressed MDD including its role as candidate biomarker.

重度抑郁症 (MDD) 是一种复杂的依赖于状态的精神疾病，但将心理物理、生化和精神病理学变化联系起来的生物标志物仍然难以捉摸。早期的研究表明，急性 MDD 中低阶枕叶皮质的 GABA 减少，尽管如此，它对高阶视觉感知的有效性和意义仍然开放。我们研究的目标是通过将视觉感知的心理物理学调查与急性抑郁 MDD 中颞中视区 (hMT+) 中 GABA 浓度的测量相结合来填补这一空白。在心理物理学上，我们观察到大量急性 MDD 受试者的视觉环绕运动抑制存在高度特异性的缺陷，重要的是，这与症状的严重程度相关。视觉缺陷及其与症状严重程度的关系在接受 MRS 的较小 MDD 样本中得到复制。使用高场 7T 质子磁共振波谱 (¹ H-MRS)，急性 MDD 受试者在视觉 MT+ 中表现出 GABA 浓度降低，这与健康受试者不同，不再与他们的视觉运动表现相关，即 SI 受损。总之，我们的心理物理-生化联合研究表明枕骨 GABA 减少对急性 MDD 中视觉感知和精神病理学症状的改变具有重要作用。我们的研究结果弥补了枕骨 GABA 的生化水平与精神病理学症状的视觉感知变化之间的差距，指出枕叶皮质在急性抑郁 MDD 中的重要性，包括其作为候选生物标志物的作用。