The prefrontal cortex conscious and unconscious response to social/emotional facial expressions involve sex, hemispheric laterality, and selective activation of the central cardiac modulation.
- 作者列表："Fogazzi DV","Neary JP","Sonza A","Reppold CT","Kaiser V","Scassola CM","Casali KR","Rasia-Filho AA
:The human prefrontal cortex (PFC) processes complex sensory information for the elaboration of social behaviors. The non-invasive neuroimaging technique near-infrared spectroscopy (NIRS) identifies hemodynamic changes and concentration of oxygenated (HbO2) and deoxygenated (HHb) hemoglobin in the cerebral cortex. We studied the responses detected by NIRS in the right and left PFC activation of 28 participants (n = 14 adult young females and males) while processing social/emotional facial expressions, i.e., in conscious perception of different expressions (neutral, happy, sad, angry, disgust, and fearful) and in unconscious/masked perception of negative expressions (fearful and disgust overlapped by neutral). The power spectral analysis from concomitant ECG signals revealed the sympathetic and parasympathetic modulation of cardiac responses. We found higher HbO2 values in the right PFC of females than in males during, and in the left PFC after, following the conscious perception of the happy face. In males, the left PFC increased and the right PFC decreased HbO2 while viewing the happy expression. In both sexes, HHb values were higher during the masked presentation of disgust than fearful expression, and after the masked presentation of fearful expression than during it. Higher sympathetic and lower parasympathetic activity (LF/ HF components) occurred in females when consciously and unconsciously processing negative emotions (p < 0.05 in all cases). These results demonstrate that the human PFC displays a selective activation depending on sex, hemispheric laterality, attention, time for responding to conscious and unconscious emotionally loaded stimuli with simulataneous centrally modulated cardiovascular responses.
: 人类前额叶皮层 (PFC) 处理复杂的感觉信息，以阐述社会行为。无创神经成像技术近红外光谱 (NIRS) 识别大脑皮层中氧合 (HbO2) 和脱氧 (HHb) 血红蛋白的血流动力学变化和浓度。我们研究了 28 名参与者 (n = 14 名成年年轻女性和男性) 在处理社交/情感面部表情时，NIRS 在右侧和左侧 PFC 激活中检测到的反应，即,有意识地感知不同的表情 (中性、快乐、悲伤、愤怒、厌恶和恐惧)和在无意识/蒙面感知的负面表达 (恐惧和厌恶由中性重叠)。来自伴随心电信号的功率谱分析揭示了心脏反应的交感神经和副交感神经调制。我们发现女性右侧 PFC 中的 HbO2 值高于男性，之后左侧 PFC 中的 HbO2 值遵循快乐面孔的有意识感知。在男性中，观察快乐表达时，左侧 PFC 增加，右侧 PFC 降低 HbO2。在两种性别中，HHb 值在厌恶的掩蔽呈现期间高于恐惧表达期间，在恐惧表达的掩蔽呈现之后高于在其期间。当有意识和无意识地处理负面情绪时，女性出现较高的交感神经和较低的副交感神经活性 (LF/ HF 成分) (所有病例 p <0.05)。这些结果表明，人类 PFC 显示出选择性激活，这取决于性别、半球偏侧性、注意力、对意识和无意识情绪负荷刺激的反应时间以及同时性中央调节心血管反应。
METHODS::In recent years, transcranial electrical stimulation (tES) has been used to improve cognitive and perceptual abilities and to boost learning. In the visual domain, transcranial random noise stimulation (tRNS), a type of tES in which electric current is randomly alternating in between two electrodes at high frequency, has shown potential in inducing long lasting perceptual improvements when coupled with tasks such as contrast detection. However, its cortical mechanisms and online effects have not been fully understood yet, and it is still unclear whether these long-term improvements are due to early-stage perceptual enhancements of contrast sensitivity or later stage mechanisms such as learning consolidation. Here we tested tRNS effects on multiple spatial frequencies and orientation, showing that tRNS enhances detection of a low contrast Gabor, but only for oblique orientation and high spatial frequency (12 cycles per degree of visual angle). No improvement was observed for low contrast and vertical stimuli. These results indicate that tRNS can enhance contrast sensitivity already after one training session, however this early onset is dependent on characteristics of the stimulus such as spatial frequency and orientation. In particular, the shallow depth of tRNS is likely to affect superficial layers of the visual cortex where neurons have higher preferred spatial frequencies than cells in further layers, while the lack of effect on vertical stimuli might reflect the optimization of the visual system to see cardinally oriented low contrast stimuli, leaving little room for short-term improvement. Taken together, these results suggest that online tRNS effects on visual perception are the result of a complex interaction between stimulus intensity and cortical anatomy, consistent with previous literature on brain stimulation.
METHODS:OBJECTIVE:There is growing interest in treating diseases by electrical stimulation and block of peripheral autonomic nerves, but a paucity of studies on excitation and block of small diameter autonomic axons. We conducted in vivo quantification of the strength-duration properties, activity-dependent slowing (ADS), and responses to kilohertz frequency (KHF) signals for the rat vagus nerve (VN). APPROACH:We conducted acute in vivo experiments in urethane-anesthetised rats. We placed two cuff electrodes on the left cervical VN and one cuff electrode on the anterior subdiaphragmatic VN. The rostral cervical cuff was used to deliver pulses to quantify recruitment and ADS. The caudal cervical cuff was used to deliver KHF signals. The subdiaphragmatic cuff was used to record compound action potentials (CAPs). MAIN RESULTS:We quantified the input-output recruitment and strength-duration curves. Fits to the data using standard strength-duration equations were qualitatively similar, but the resulting chronaxie and rheobase estimates varied substantially. We measured larger thresholds for the slowest fibres (0.5 to 1 m/s), especially at shorter pulse widths. Using a novel cross-correlation CAP-based analysis, we measured ADS of ~2.3% after 3 min of 2 Hz stimulation, which is comparable to ADS reported for sympathetic efferents in somatic nerves, but much smaller than ADS in cutaneous nociceptors. We found greater ADS with higher stimulation frequency and non-monotonic changes in CV in select cases. We found monotonically increasing block thresholds across frequencies from 10 to 80 kHz for both fast and slow fibres. Further, following 25 s of KHF signal, neural conduction could require tens of seconds to recover. SIGNIFICANCE:The quantification of mammalian autonomic nerve responses to conventional and KHF signals provides essential information for development of peripheral nerve stimulation therapies and for understanding their mechanisms of action.
METHODS:BACKGROUND:Early accounts of forced thought were reported at the onset of a focal seizure, and characterized as vague, repetitive, and involuntary intellectual auras distinct from perceptual or psychic hallucinations or illusions. Here, we examine the neural underpinnings involved in conceptual thought by presenting a series of 3 patients with epilepsy reporting intrusive thoughts during electrical stimulation of the left lateral prefrontal cortex (PFC) during invasive surgical evaluation. We illustrate the widespread networks involved through two independent brain imaging modalities: resting state functional magnetic resonance imaging (fMRI) (rs-fMRI) and task-based meta-analytic connectivity modeling (MACM). METHODS:We report the clinical and stimulation characteristics of three patients with left hemispheric language dominance who demonstrate forced thought with functional mapping. To examine the brain networks underlying this phenomenon, we used the regions of interest (ROI) centered at the active electrode pairs. We modeled functional networks using two approaches: (1) rs-fMRI functional connectivity analysis, representing 81 healthy controls and (2) meta-analytic connectivity modeling (MACM), representing 8260 healthy subjects. We also determined the overlapping regions between these three subjects' rs-fMRI and MACM networks through a conjunction analysis. RESULTS:We identified that left PFC was associated with a large-scale functional network including frontal, temporal, and parietal regions, a network that has been associated with multiple cognitive functions including semantics, speech, attention, working memory, and explicit memory. CONCLUSIONS:We illustrate the neural networks involved in conceptual thought through a unique patient population and argue that PFC supports this function through activation of a widespread network.