INTRODUCTION Brain insulin reactivity has been reported in connection with systematic energy metabolism, enhancement in cognition, olfactory sensitivity and neuroendocrine circuits. High receptor densities exist in regions important for sensory processing. The main aim of the study was to examine whether intranasal insulin would modulate the activity of areas in charge of olfactory-visual integration. METHODS As approach, a placebo-controlled double-blind within crossover design was chosen. The experiments were conducted in a research unit of a university hospital. On separate mornings, twenty-six healthy normal-weight males aged between 19 and 31 years received either 40 IU intranasal insulin or placebo vehicle. Subsequently, they underwent 65 min of functional magnetic resonance imaging whilst performing an odor identification task. Functional brain activations of olfactory, visual and multisensory integration as well as insulin vs. placebo were assessed. Regarding the odor identification task, reaction time, accuracy, pleasantness and intensity measurements were taken to examine the role of integration and treatment. Blood samples were drawn to control for peripheral hormone concentrations. RESULTS Intranasal insulin administration during olfactory-visual stimulation revealed strong bilateral engagement of frontoinsular cortices, anterior cingulate, prefrontal cortex, mediodorsal thalamus, striatal and hippocampal regions (p ≤ .001 FWE corrected). In addition, the integration contrast showed increased activity in left intraparietal sulcus, left inferior frontal gyrus, left superior frontal gyrus and left middle frontal gyrus (p ≤ .013 FWE corrected). CONCLUSIONS Intranasal insulin application in lean men led to enhanced activation in multisensory olfactory-visual integration sites and salience hubs which indicates stimuli valuation modulation. This effect can serve as a basis for understanding the connection of intracerebral insulin and olfactory-visual processing.

中文翻译：

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在多感官知觉过程中，胰岛素水平升高会影响显着网络。

引言 据报道，脑胰岛素反应性与系统能量代谢、认知增强、嗅觉敏感性和神经内分泌回路有关。对于感觉处理重要的区域存在高受体密度。该研究的主要目的是检查鼻内胰岛素是否会调节负责嗅觉-视觉整合的区域的活动。方法 作为方法，选择了交叉设计中安慰剂对照的双盲法。实验是在一所大学医院的研究单位进行的。在不同的早晨，26 名年龄在 19 岁至 31 岁之间的健康正常体重男性接受了 40 IU 鼻内胰岛素或安慰剂载体。随后，他们在执行气味识别任务的同时接受了 65 分钟的功能磁共振成像。评估了嗅觉、视觉和多感觉整合的功能性大脑激活以及胰岛素与安慰剂的比较。关于气味识别任务，通过反应时间、准确性、愉悦感和强度测量来检验整合和治疗的作用。抽取血样以控制外周激素浓度。结果 嗅觉-视觉刺激期间鼻内胰岛素给药显示额岛皮质、前扣带皮层、前额叶皮质、丘脑内侧、纹状体和海马区域的双侧强烈参与（p ≤ .001 FWE 校正）。此外，整合对比显示左侧顶内沟、左侧额下回、左侧额上回和左侧额中回的活动增加（p ≤ .013 FWE 校正）。结论 瘦男性鼻内胰岛素应用导致多感觉嗅觉-视觉整合位点和显着中枢的激活增强，这表明刺激评估调节。这种效应可以作为理解脑内胰岛素和嗅觉视觉处理之间的联系的基础。