这并不是说，不良时刻的记忆就不会被存储与回忆。重点是它们在目前心智中占有多少的分量。记忆的细节都还在，当然可以从中产生令人难以忍受的痛苦感觉。但相较于美好记忆在回忆中展现出更为美好的状况，不好的记忆可能就没有随着时间而增强。这种情况不是为了抑制不良记忆的细节，而是要减少细节停留的时间，以消除不良记忆的负面影响。结果就是幸福感自动大量增加105。丹尼尔·康纳曼（Daniel Kahneman）与艾莫斯·特维斯基（Amos Tversky）所描述的峰终效应（peak-end effect）对此也有所贡献。我们倾向于为过去场景中更有价值的方面创造强大的记忆，并让其余部分变得模糊。记忆其实并不完美106。
并不是每个人的记忆都有这种情感上的正面重塑。有些人认为他们的回忆就完全是原有的那样，没有变得更好也没有变得更差。可以想见，我们当中的悲观主义者就会表示记忆变得负面了。但所有这些都很难衡量与评判，因为我们有着不同的情感类型，所以我们的生命过程会有很大的差异。
为什么思考这种现象很重要？其中一个原因与对未来的期望有关。人们对未来生活的期望与面对方式，取决于过去的生活方式，不仅仅在于客观可验证的实际上，也在于记忆中客观数据的体验或重建上。让我们每个人成为独特个体是回忆的恩赐。我们个性在众多方面的风格，与认知及情感的典型模式有关，也与个体情感体验的协调、文化认同、成就及运气有关。
我们所创造的文化与创造文化的方式，以及我们对文化现象做出反应的方式，都受到我们不完美的记忆所操弄，而记忆又在感觉的掌控之中。
76 Pierre Beaulieu et al., Pharmacology of Pain (Philadelphia: Lippincott Williams & Wilkins, 2015).
77 George B. Stefano, Beatrice Salzet, and Gregory L. Fricchione, “Enkelytin and Opioid Peptide Association in Invertebrates and Vertebrates: Immune Activation and Pain,” Immunology Today 19, no. 6 (1998): 265–68; Michel Salzet and Aurélie Tasiemski, “Involvement of Pro-enkephalin-derived Peptides in Immunity,” Developmental and Comparative Immunology 25, no. 3 (2001): 177–85; Halina Machelska and Christoph Stein, “Leukocyte-Derived Opioid Peptides and Inhibition of Pain,” Journal of Neuroimmune Pharmacology 1, no. 1 (2006): 90–97; Simona Farina, Michele Tinazzi, Domenica Le Pera, and Massimiliano Valeriani, “Pain-Related Modulation of the Human Motor Cortex,” Neurological Research 25, no. 2 (2003): 130–42; Stephen B. McMahon, Federica La Russa, and David L. H. Bennett, “Crosstalk Between the Nociceptive and Immune Systems in Host Defense and Disease,” Nature Reviews Neuroscience 16, no. 7 (2015): 389–402.
78 Brunet and Arendt, “From Damage Response to Action Potentials”; Hoffman et al., “Aminoglycoside Antibiotics Induce Bacterial Biofilm Formation”; Naviaux, “Metabolic Features of the Cell Danger Response”; Icard-Arcizet et al., “Cell Stiffening in Response to External Stress Is Correlated to Actin Recruitment”; Kearns, “Field Guide to Bacterial Swarming Motility”; Erill, Campoy, and Barbé, “Aeons of Distress.”
瞬时受体电位（TRP）离子信道作为单细胞生物体中的传感器，并在整个系统发生的过程之中被保留下来。例如在无脊椎动物中，这些传感器可以检测如酷热之类的恶劣环境状态，因此对于导航安全至关重要。检测恶劣状态的设备与神经系统的结合，最终产生了一类称为疼痛传感器的感觉神经元。
疼痛传感器分布在整个身体组织中，并配备有高阈值瞬时受体电位离子通道，可对其他无害知觉的强烈感受产生反应。疼痛传感器也配备有类铎受体（TLR），这是遍布全身的免疫系统卫兵。类铎受体的活化会引发免疫反应，当疼痛传感器的类铎受体被活化时，它们会引发强而有力的局部发炎反应，并让局部疼痛传感器类铎受体通道变得敏感，造成与伤害或感染的疼痛相关的敏感性增加。疼痛接续会抑制其运动皮质，甚至已被证明，会经由活化拮抗肌肉群组来抑制运动本身的启动。受伤时，这可以防止额外的伤害。
疼痛感觉传入神经处理疼痛与损伤，而非疼痛感觉传入神经则收集有关生物体内外部情况的其他相关信息，以形成同步处理的意象。神经系统能让感官刺激进行精确定位，也能协调将所有主要生命调节系统整合纳入恒定作用中的复杂多样生理过程。
Giorgio Santoni, Claudio Cardinali, Maria Beatrice Morelli, Matteo Santoni, Massimo Nabissi, and Consuelo Amantini, “Danger- and Pathogen-Associated Molecular Patterns Recognition by Pattern-Recognition Receptors and Ion Channels of the Transient Receptor Potential Family Triggers the Inflammasome Activation in Immune Cells and Sensory Neurons,” Journal of Neuroinflammation 12, no. 1 (2015): 21; McMahon, La Russa, and Bennett, “Crosstalk Between the Nociceptive and Immune Systems in Host Defense and Disease”; Ardem Patapoutian, Simon Tate, and Clifford J. Woolf, “Transient Receptor Potential Channels: Targeting Pain at the Source,” Nature Reviews Drug Discovery 8, no. 1 (2009): 55–68; Takaaki Sokabe and Makoto Tominaga, “A Temperature-Sensitive TRP Ion Channel, Painless, Functions as a Noxious Heat Sensor in Fruit Flies,” Communicative and Integrative Biology 2, no. 2 (2009): 170–73; Farina et al., “Pain-Related Modulation of the Human Motor Cortex.”
79 Santoni et al., “Danger- and Pathogen-Associated Molecular Patterns Recognition by Pattern-Recognition Receptors and Ion Channels of the Transient Receptor Potential Family Triggers the Inflammasome Activation in Immune Cells and Sensory Neurons”; Sokabe and Tominaga, “Temperature-Sensitive TRP Ion Channel, Painless, Functions as a Noxious Heat Sensor in Fruit Flies.”
80 Colin Klein and Andrew B. Barron, “Insects Have the Capacity for Subjective Experience,” Animal Sentience 1, no. 9 (2016): 1.
虽然水螅内部的神经网络可能无法产生意象甚至是表征，但居中的步骤正在形成。类铎受体是一种内部受体，此受体活化即表示出现病原体入侵或组织受到热休克或其他有害状况的伤害。在水螅内部发现到类铎受体，因此该受体出现的时间比依赖神经系统作用的对照绘图功能更早。类铎受体对损伤或病原体相关分子模式的特别敏感性，使它能够活化引发出特定情绪和先天性免疫反应。这种在检测/反应上的特殊性，比单细胞生物体中存在的瞬时受体电位离子通道所促进的一般感觉更上一层楼。S·ren Franzenburg, Sebastian Fraune, Sven Künzel, John F. Baines, Tomislav Domazet-Lo·o, and Thomas C. G. Bosch, “My D88-Deficient Hydra Reveal an Ancient Function of TLR Signaling in Sensing Bacterial Colonizers,” Proceedings of the National Academy of Sciences 109, no. 47 (2012): 19374–79; Bosch et al., “Uncovering the Evolutionary History of Innate Immunity.”
81 感觉可创造出生死之间的差异。每个活体生物在测得环境情况时，必须对其做出反应，然而许多情况下，确定环境恒定相关特性所需的时间则攸关生存。动物若能够从熟悉的环境线索中预测到掠食者的存在，就会有更好的生存机会，而感觉就具有这样的功效。
对制约场地嫌恶／偏好现象的研究探讨了这个议题。实验中的动物被训练到能够将基本环境线索与恒定相关刺激联想在一起，这样即使恒定相关刺激不存在，环境线索本身也能够开始引发反应。不具备有感觉能力的生物体，不太可能发生这种灵活的学习情况。要发生这种情况，首先必须要有特定环境线索的内部表征，以及生理痛苦的表征，以便这两种模式可以结合起来。等下一次检测到这样的环境线索时，它们就会引发相关的生理状态。
感觉能力让动物能够以反映其自身过去经验的方式，根据外部环境的感觉状态进行预测并做出反应。这种主观恒定相关性对其他一般环境刺激的投射，让生物体的生存力与生产力明显增加。请参考：Cindee F. Robles, Marissa Z. McMackin, Katharine L. Campi, Ian E. Doig, Elizabeth Y. Takahashi, Michael C. Pride, and Brian C. Trainor, “Effects of Kappa Opioid Receptors on Conditioned Place Aversion and Social Interaction in Males and Females,” Behavioural Brain Research 262 (2014): 84–93; M. T. Bardo, J. K. Rowlett, and M. J. Harris, “Conditioned Place Preference Using Opiate and Stimulant Drugs: A Meta-analysis,” Neuroscience and Biobehavioral Reviews 19, no. 1 (1995): 39–51.
82 对于任何形式的组织损伤或感染，先天性免疫系统的活化可产生一般保护性反应。虽然如此，但适应性免疫系统（约于四亿五千万年前在下颌脊椎动物中演化形成）则是直接针对特定病原体进行攻击。适应性免疫系统一旦辨识出病原体，就会针对该病原体产生特定分子。当这些分子后来检测到病原体时，免疫细胞军团就会迅速成形，搜寻扫荡身体内具有入侵者分子特征的细胞。为了维系生物体的生命，适应性免疫系统会记下这些特征。反复暴露于病原体之下，还会让适应性免疫反应随着时间更为增强。Martin F. Flajnik and Masanori Kasahara, “Origin and Evolution of the Adaptive Immune System: Genetic Events and Selective Pressures,” Nature Reviews Genetics 11, no. 1 (2010): 47–59.
83 Klein and Barron, “Insects Have the Capacity for Subjective Experience.”
84 Yasuko Hashiguchi, Masao Tasaka, and Miyo T. Morita, “Mechanism of Higher Plant Gravity Sensing,” American Journal of Botany 100, no. 1 (2013): 91–100; Alberto P. Macho and Cyril Zipfel, “Plant PRRs and the Activation of Innate Immune Signaling,” Molecular Cell 54, no. 2 (2014): 263–72.
85 我的同事金森·曼（Kingson Man）建议以「连续性」（continuity）一词来表示神经与身体发生相互作用的状态。
86 传统的东方形而上学思想体系认为，虽然二元性是人类感知正常模式所固有的，但我们所感知到的那个充满离散且独立物体或现象的世界，是种感知屏障，掩盖了现实中更基本的「非二元性」基质。「非二元性」描述了一个全然相互依赖的世界，其中心智、身体与所有现象都是纠结在一起的。尽管这种观点与西方主流文化典范不兼容，但一些西方哲学家，特别是史宾诺莎，也得出了类似的结论。传统东方思想的这些支柱与当前自然科学之间的相似之处仍持续发掘中。举例来说，量子物理学中的卓越发现，显示了在我们感官所感知之离散且客观的现实之下，存在着更多相关动态的相互作用力，这些力量挑战着主流观点。David Loy, Nonduality: A Study in Comparative Philosophy (Amherst, N.Y.: Humanity Books, 1997);Vlatko Vedral, Decoding Reality: The Universe as Quantum Information (New York: Oxford University Press, 2012).
87 Arthur D. Craig, “How Do You Feel· Interoception: The Sense of the Physiological Condition of the Body,” Nature Reviews Neuroscience 3, no. 8 (2002): 655–66; Arthur D. Craig, “Interoception: The Sense of the Physiological Condition of the Body,” Current Opinion in Neurobiology 13, no. 4 (2003): 500–505; Arthur D. Craig, “How Do You Feel—Now· The Anterior Insula and Human Awareness,” Nature Reviews Neuroscience 10, no. 1 (2009); Hugo D. Critchley, Stefan Wiens, Pia Rotshtein, Arne ·hman, and Raymond J. Dolan, “Neural Systems Supporting Interoceptive Awareness,” Nature Neuroscience 7, no. 2 (2004): 189–95.
88 Alexander J. Shackman, Tim V. Salomons, Heleen A. Slagter, Andrew S. Fox, Jameel J. Winter, and Richard J. Davidson, “The Integration of Negative Affect, Pain, and Cognitive Control in the Cingulate Cortex,” Nature Reviews Neuroscience 12, no. 3 (2011): 154–67.
89 在没有人注意到皮质下神经核的那个时期，潘克沙普是这方面研究的第一人。而这方面想法目前已经获得其他研究充分支持，包括我们的研究：Damasio et al., “Subcortical and Cortical Brain Activity During the Feeling of Self-Generated Emotions.” 灵长类的脑干解剖位置则在Parvizi and Damasio, “Consciousness and the Brainstem”中有极佳说明。
90 这些神经核的重要性来自于，其所接收之有关恒定状态变化的大量投射。Esther-Marije Klop, Leonora J. Mouton, Rogier Hulsebosch, José Boers, and Gert Holstege, “In Cat Four Times as Many Lamina I Neurons Project to the Parabrachial Nuclei and Twice as Many to the Periaqueductal Gray as to the Thalamus,” Neuroscience 134, no. 1 (2005): 189–97.
91 Michael M. Behbehani, “Functional Characteristics of the Mid-brain Periaqueductal Gray,” Progress in Neurobiology 46, no. 6 (1995): 575–605.
92 Craig, “How Do You Feel·”; Craig, “Interoception”; Craig, “How Do You Feel—Now·”; Critchley et al., “Neural Systems Supporting Interoceptive Awareness”; Richard P. Dum, David J. Levinthal, and Peter L. Strick, “The Spinothalamic System Targets Motor and Sensory Areas in the Cerebral Cortex of Monkeys,” Journal of Neuroscience 29, no. 45 (2009): 14223–35; Antoine Louveau, Igor Smirnov, Timothy J. Keyes, Jacob D. Eccles, Sherin J. Rouhani, J. David Peske, Noel C. Derecki, “Structural and Functional Features of Central Nervous System Lymphatic Vessels,” Nature 523, no. 7560 (2015): 337–41.
93 Michael J. McKinley, The Sensory Circumventricular Organs of the Mammalian Brain: Subfornical Organ, OVLT, and Area Postrema (New York: Springer, 2003); Robert E. Shapiro and Richard R. Miselis, “The Central Neural Connections of the Area Postrema of the Rat,” Journal of Comparative Neurology 234, no. 3 (1985): 344–64.
94 Marshall Devor, “Unexplained Peculiarities of the Dorsal Root Ganglion,” Pain 82 (1999): S27–S35.
95 He-Bin Tang, Yu-Sang Li, Koji Arihiro, and Yoshihiro Nakata, “Activation of the Neurokinin-1 Receptor by Substance P Triggers the Release of Substance P from Cultured Adult Rat Dorsal Root Ganglion Neurons,” Molecular Pain 3, no. 1 (2007): 42.
96 J. A. Kiernan, “Vascular Permeability in the Peripheral Autonomic and Somatic Nervous Systems: Controversial Aspects and Comparisons with the Blood-Brain Barrier,” Microscopy Research and Technique 35, no. 2 (1996): 122–36.
97 Malin Bj·rnsdotter, India Morrison, and H·kan Olausson, “Feeling Good: On the Role of C Fiber Mediated Touch in Interoception,” Experimental Brain Research 207, no. 3–4 (2010): 149–55; A. Harper and S. N. Lawson, “Conduction Velocity Is Related to Morphological Cell Type in Rat Dorsal Root Ganglion Neurones,” Journal of Physiology 359 (1985): 31.
98 Damasio and Carvalho, “Nature of Feelings”; Ian A. McKenzie, David Ohayon, Huiliang Li, Joana Paes De Faria, Ben Emery, Koujiro Tohyama, and William D. Richardson, “Motor Skill Learning Requires Active Central Myelination,” Science 346, no. 6207 (2014): 318–22.
99 我们小组的持续研究显示，周边神经系统神经节中的非突触传递受到一种普遍存在的神经传导物质所控制，此神经传导物质对于突触传递以及疼痛、感官知觉、平滑肌收缩与许多其他身体功能也具有关键作用。有趣的是，这种多元化分子不会任意影响神经元。这种分子似乎对无髓鞘的古老C型神经元保留了最戏剧性的影响，而C型神经元形成了我们绝大部分的内感受路径，并可能在产生感觉上发挥作用。请参考：Damasio and Carvalho, “Nature of Feelings”; Bj·rnsdotter, Morrison, and Olausson, “Feeling Good”; Gang Wu, Matthias Ringkamp, Timothy V. Hartke, Beth B. Murinson, James N. Campbell, John W. Griffin, and Richard A. Meyer, “Early Onset of Spontaneous Activity in Uninjured C-Fiber Nociceptors After Injury to Neighboring Nerve Fibers,” Journal of Neuroscience 21, no. 8 (2001): RC140; R. Douglas Fields, “White Matter in Learning, Cognition, and Psychiatric Disorders,” Trends in Neurosciences 31, no. 7 (2008): 361–70; McKenzie et al., “Motor Skill Learning Requires Active Central Myelination”; Julia J. Harris and David Attwell, “The Energetics of CNS White Matter,” Journal of Neuroscience 32, no. 1 (2012): 356–71; Richard A. Meyer, Srinivasa N. Raja, and James N. Campbell, “Coupling of Action Potential Activity Between Unmyelinated Fibers in the Peripheral Nerve of Monkey,” Science 227 (1985): 184–88; Hemant Bokil, Nora Laaris, Karen Blinder, Mathew Ennis, and Asaf Keller, “Ephaptic Interactions in the Mammalian Olfactory System,” Journal of Neuroscience 21 (2001): 1–5; Henry Harland Hoffman and Harold Norman Schnitzlein, “The Numbers of Nerve Fibers in the Vagus Nerve of Man,” Anatomical Record 139, no. 3 (1961): 429–35; Marshall Devor and Patrick D. Wall, “Cross-Excitation in Dorsal Root Ganglia of Nerve-Injured and Intact Rats,” Journal of Neurophysiology 64, no. 6 (1990): 1733–46; Eva Sykova, “Glia and Volume Transmission During Physiological and Pathological States,” Journal of Neural Transmission 112, no. 1 (2005): 137–47.
100 Emeran Mayer, The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health (New York: HarperCollins, 2016).
101 Jane A. Foster and Karen-Anne McVey Neufeld, “Gut-Brain Axis: How the Microbiome Influences Anxiety and Depression,” Trends in Neurosciences 36, no. 5 (2013): 305–12; Mark Lyte and John F. Cryan, eds., Microbial Endocrinology: The Microbiota-Gut-Brain Axis in Health and Disease (New York: Springer, 2014); Mayer, Mind-Gut Connection.
102 Doe-Young Kim and Michael Camilleri, “Serotonin: A Mediator of the Brain-Gut Connection,” American Journal of Gastroenterology 95, no. 10 (2000): 2698.
103 Timothy R. Sampson, Justine W. Debelius, Taren Thron, Stefan Janssen, Gauri G. Shastri, Zehra Esra Ilhan, Collin Challis et al., “Gut Microbiota Regulate Motor Deficits and Neuroinflammation in a Model of Parkinson’s Disease,” Cell 167, no. 6 (2016): 1469–80.
104 悲伤必定有碍健康，但感恩之类的正面状态似乎具有不同效果。当我们获得有意义的援助或支持时，会产生感恩；前述援助或支持是由同情心所引发，并且对健康与生活质量有显著的正面影响。我同事格伦·福克斯（Glenn Fox）最近进行的一项功能性核磁共振造影（fMRI）研究，解释了与感恩有关的神经因素，研究报告显示，有意义的感恩体验与某些区域的脑部活动有关，包括了传统认为是主控压力调节、社会认知与道德推理的脑部区域。这项发现支持过往的研究结果，那就是内心常怀感恩有益健康，而这又强调出心智与身体间之连续性的概念。请参考：Glenn R. Fox, Jonas Kaplan, Hanna Damasio, and Antonio Damasio, “Neural Correlates of Gratitude,” Frontiers in Psychology 6 (2015); Alex M. Wood, Stephen Joseph, and John Maltby, “Gratitude Uniquely Predicts Satisfaction with Life: Incremental Validity Above the Domains and Facets of the Five Factor Model,” Personality and Individual Differences 45, no. 1 (2008): 49–54; Max Henning, Glenn R. Fox, Jonas Kaplan, Hanna Damasio, and Antonio Damasio, “The Positive Effects of Gratitude Are Mediated by Physiological Mechanisms,” Frontiers in Psychology (2017).
105 Sarah J. Barber, Philipp C. Opitz, Bruna Martins, Michiko Sakaki, and Mara Mather, “Thinking About a Limited Future Enhances the Positivity of Younger and Older Adults’ Recall: Support for Socioemotional Selectivity Theory,” Memory and Cognition 44, no. 6 (2016): 869–82; Mara Mather, “The Affective Neuroscience of Aging,” Annual Review of Psychology 67 (2016): 213–38.
106 Daniel Kahneman, “Experienced Utility and Objective Happiness: A Moment-Based Approach,” in Choices, Values, and Frames, eds. Daniel Kahneman and Amos Tversky (New York: Russell Sage Foundation, 2000); Daniel Kahneman, “Evaluation by Moments: Past and Future,” in ibid.; Bruna Martins, Gal Sheppes, James J. Gross, and Mara Mather, “Age Differences in Emotion Regulation Choice: Older Adults Use Distraction Less Than Younger Adults in High-Intensity Positive Contexts,” Journals of Gerontology Series B: Psychological Sciences and Social Sciences (2016): gbw028.
