For a coherent and meaningful life, conscious self-representation is mandatory. Such explicit ''autonoetic consciousness'' is thought to emerge by retrieval of memory of personally experienced events (''episodic memory''). During episodic retrieval, functional imaging studies consistently show differential activity in medial prefrontal and medial parietal cortices. With positron-emission tomography, we here show that these medial regions are functionally connected and interact with lateral regions that are activated according to the degree of self-reference. During retrieval of previous judgments of Oneself, Best Friend, and the Danish Queen, activation increased in the left lateral temporal cortex and decreased in the right inferior parietal region with decreasing self-reference. Functionally, the former region was preferentially connected to medial prefrontal cortex, the latter to medial parietal. The medial parietal region may, then, be conceived of as a nodal structure in self-representation, functionally connected to both the right parietal and the medial prefrontal cortices. To determine whether medial parietal cortex in this network is essential for episodic memory retrieval with self-representation, we used transcranial magnetic stimulation over the region to transiently disturb neuronal circuitry. There was a decrease in the efficiency of retrieval of previous judgment of mental Self compared with retrieval of judgment of Other with transcranial magnetic stimulation at a latency of 160 ms, confirming the hypothesis. This network is strikingly similar to the network of the resting conscious state, suggesting that self-monitoring is a core function in resting consciousness.A ll subjective experience may be seen as self-conscious in the weak sense that there is something it feels like for the subject to have that experience. We may at times be selfconscious in a deep way, for example, when we are engaged in figuring out who we are and what we are going to do with our lives, a distinctly human experience giving organization, meaning, and structure to life. In its absence, our representation of ourselves and our world becomes kaleidoscopic and our life chaotic (1).Such explicit ''autonoetic consciousness'' is thought to emerge by retrieval of memory of personally experienced events (episodic memory) (2, 3). The cerebral activation pattern of episodic memory retrieval differs from that of semantic retrieval (retrieval of common knowledge by ''familiarity''): e.g., activation of medial parietal cortex is characteristic of the former and activation of left lateral temporal lobe is characteristic of the latter (4). First, we hypothesize that the cerebral activity pattern of retrieval of previous judgments of a person is determined not only by the episodic retrieval nature of the task, but also by the degree of self-reference of the judgment to be retrieved. Second, we hypothesize that the regions activated by retrieval of judgment of the mental Self are functionally interacting. This network would give a distinc...
Functional magnetic resonance imaging (fMRI) was used to compare brain activation to static facial displays versus dynamic changes in facial identity or emotional expression. Static images depicted prototypical fearful, angry and neutral expressions. Identity morphs depicted identity changes from one person to another, always with neutral expressions. Emotion morphs depicted expression changes from neutral to fear or anger, creating the illusion that the actor was 'getting scared' or 'getting angry' in real-time. Brain regions implicated in processing facial affect, including the amygdala and fusiform gyrus, showed greater responses to dynamic versus static emotional expressions, especially for fear. Identity morphs activated a dorsal fronto-cingulo-parietal circuit and additional ventral areas, including the amygdala, that also responded to the emotion morphs. Activity in the superior temporal sulcus discriminated emotion morphs from identity morphs, extending its known role in processing biologically relevant motion. The results highlight the importance of temporal cues in the neural coding of facial displays.
Caramel color is added to many widely-consumed beverages as a colorant. Consumers of these beverages can be exposed to 4-methylimidazole (4-MEI), a potential carcinogen formed during its manufacture. California’s Proposition 65 law requires that beverages containing 4-MEI concentrations corresponding to exposures that pose excess cancer risks > 1 case per 100,000 exposed persons (29 μg 4-MEI/day) carry warning labels. Using ultrahigh-performance liquid chromatography-tandem mass spectrometry, we assessed 4-MEI concentrations in 12 beverages purchased in California and a geographically distant metropolitan area (New York) in which warning labels are not required. In addition, we characterized beverage consumption by age and race/ethnicity (using weighted means calculated from logistic regressions) and assessed 4-MEI exposure and resulting cancer risks and US population cancer burdens attributable to beverage consumption. Data on beverage consumption were obtained from the National Health and Nutrition Examination Survey, dose-response data for 4-MEI were obtained from the California Environmental Protection Agency Office of Environmental Health Hazards Assessment, and data on population characteristics were obtained from the U.S. Census Bureau. Of the 12 beverages, Malta Goya had the highest 4-MEI concentration (915.8 to 963.3μg/L), lifetime average daily dose (LADD - 8.04x10-3 mg/kgBW-day), lifetime excess cancer risk (1.93x10-4) and burden (5,011 cancer cases in the U.S. population over 70 years); Coca-Cola had the lowest value of each (4-MEI: 9.5 to 11.7μg/L; LADD: 1.01x10-4 mg/kgBW-day; risk: 1.92x10-6; and burden: 76 cases). 4-MEI concentrations varied considerably by soda and state/area of purchase, but were generally consistent across lots of the same beverage purchased in the same state/area. Routine consumption of certain beverages can result in 4-MEI exposures > 29 μg/day. State regulatory standards appear to have been effective in reducing exposure to carcinogens in some beverages. Federal regulation of 4-MEI in caramel color may be appropriate.
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