An Investigation Into the Neural Substrates of Virtue to Determine the Key Place of Virtues in Human Moral Development
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University of Notre Dame Australia ResearchOnline@ND Theses 2012 An investigation into the neural substrates of virtue to determine the key place of virtues in human moral development Andrew P.L Mullins University of Notre Dame Australia Follow this and additional works at: http://researchonline.nd.edu.au/theses Part of the Religion Commons COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING The am terial in this communication may be subject to copyright under the Act. Any further copying or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice. Publication Details Mullins, A. P. (2012). An investigation into the neural substrates of virtue to determine the key place of virtues in human moral development (Doctor of Philosophy (PhD)). University of Notre Dame Australia. http://researchonline.nd.edu.au/theses/78 This dissertation/thesis is brought to you by ResearchOnline@ND. It has been accepted for inclusion in Theses by an authorized administrator of ResearchOnline@ND. For more information, please contact [email protected]. An investigation into the neural substrates of virtue to determine the key place of virtues in human moral development. Research thesis submitted for the degree of Doctor of Philosophy. Andrew P. J. Mullins School of Philosophy and Theology University of Notre Dame, Australia. December 2012. 1 2 Table of Contents Abstract. Declaration of Authorship. Acknowledgements. Abbreviations. Chapter 1 Page Aristotle and the neuroscientists sit down to talk. 1.1. The structure of this study. ………………………………….……………... 21 1.2. Preamble. The prima facie case. ………………………………………….. 22 1.2.1 Material and non-material constituents to human rationality. 1.2.1.1. We are not disembodied spirits. Evidence of the involvement of the physical in rationality. 1.2.1.2. Nor are we mere bodies. Intimations of the non-material. 1.2.1.3. A prima facie case exists for a profound integration of the physical and rational in the human person. 1.2.2. Prima facie evidence for a neuronal underpinning of virtue. 1.3. Situating this study within contemporary approaches to the philosophy of mind. …………………………………………………………….. 34 1.4. The hylomorphic underpinnings of this study. …………………….. 37 1.4.1 An overview of hylomorphic theory. a) Substance. b) Soul. 1.4.2 Rational psychology. 1.4.3 Restoring the hylomorphic notion of person. 1.4.4 Advantages offered by an hylomorphic notion of person. 1.5. An hylomorphic critique of 20th century currents in philosophy of mind. …………………………………………………………….. 65 1.6. Situating this study in current approaches to ethics. ……………. 70 1.6.1 Some reasons for the growing stature of virtue ethics. 1.6.2 Within virtue ethics there exists a spectrum of significantly contrasting approaches. 1.6.3 This study is situated under the umbrella of eudaimonist virtue ethics. 1.7 An overview of the potential benefits of this study. …………….. 81 1.8 Conclusion. ………………………………………………………………………….. 83 3 Chapter 2 Neural mechanisms and systems. 2.1 Overview. ……………………………………………………………………………. 85 2.1.1 Rationale for the structure adopted. 2.1.1.1 Imaging the brain. 2.1.1.2 Prima facie confirmation for the broad direction of this investigation: Projects recognised in the 2009 Templeton Positive Neuroscience Awards. 2.1.1.3 The human act provides insight into the function of virtue. 2.1.1.4 Insights into the basal ganglia. a) Pathological insights into dysfunctional basal ganglia: Huntington disease, Obsessive Compulsive Disorder, Parkinson disease and Encephalitis Lethargica. b) A role for the basal ganglia in volitional habits. 2.1.2 Search information. 2.1.3 This neuroscientific investigation carries some caveats. a) The brain is constantly in a state of change. b) Our appreciation of the complexity of brain networking is at a rudimentary level. c) The basis of the interface between molecular processes and conscious processes, such as learning and memory, is still conjectural. d) Our experimental knowledge of brain function is derived from animal as well as human studies. e) Our capacity to study neuronal activity in real time and with precision is uneven and still developing. 2.2 Plasticity. …………………………………………………………………………….. 107 2.2.1 Historical considerations. 2.2.2 Plasticity is categorised as functional or structural. 2.2.3 The big picture: synaptic strengthening as the net result of structural plasticity. 2.2.4 Developmental plasticity. 2.2.4.1 Sensitive periods in humans. 2.2.4.2 Mechanisms of developmental phases. a) Experience tuned development. b) The role of axons. c) Synapse formation and elimination. 2.2.5 Other synaptic factors. 2.2.5.1 NMDAR and AMPAR mediated plasticities. a) NMDA plasticities. b) Interplay with AMPARs. 2.2.5.2 DA and the GPCR receptor. 2.2.5.3 Neurotrophic factors. 4 2.2.5.4 Other chemical signalling systems. a) Ca2+. b) ACh. c) Other chemical signalling. d) Desensitization. 2.2.5.5 Astrocytes at the synapse. 2.2.5.6 Structural considerations. a) Dendritic spines. b) Dendritic processing facilitates plasticity and cortical control. c) The speed of morphological change. d) Plasticity as a consequence of neurogenesis. e) Microtubule assembly. 2.2.6 Use-induced plasticities. 2.2.7 Exercise induced plasticity. 2.2.8 Plasticity induced by transcranial stimulation. 2.3. Neural bases for learning and memory. ………………………………. 144 2.3.1 Learning and memory. a) Learning. b) Memory. 2.3.2 The five major memory regions of the brain. a) Hippocampus. b) Amygdala. c) Striatum. d) Cerebellum. e) Cerebral cortex. 2.3.3 Mechanisms of memory. 2.3.3.1 Declarative memory storage. 2.3.3.2 Non-declarative, or procedural memory, storage. 2.3.3.3 Working memory, a form of short term memory, storage. 2.3.4 LTP as an underpinning mechanism for memory. 2.3.4.1 Further factors for the synaptic facilitation involved in memory. 2.3.4.2 The neuroscience of memory enhancement. 2.3.5 Skill related learning. 2.3.6 Neural systems of imitation and learning. 2.3.6.1 Neural systems for affective feelings. 2.3.6.2 Neuropeptides and mechanisms of trust. 2.4 Habit formation and the role of the basal ganglia. ………………. 165 2.4.1 The basal ganglia and related structures. 2.4.1.1 A key functional division of the basal ganglia. a) The ventral pars. b) The dorsal pars. 2.4.2 An overview of the contribution of the basal ganglia. 2.4.3 Connectivity to the basal ganglia. 5 a) Inputs. b) Outputs. 2.4.4 Loops. 2.4.4.1 Frontal lobe-basal gaglia loops provide a key to complex goal directed behaviours. 2.4.5 The role of the basal ganglia in motor learning. a) Motor learning as a form of memory. b) The learning process: from the explicit to the automatized. c) The comparative roles of the cerebellum and the basal ganglia. d) Numerous brain areas are implicated at both acquisition and completion stages of this learning process. e) Emotion and procedural memory. 2.4.6 Habit formation, a particular form of learning. 2.4.7 Plasticity in the basal ganglia and related structures. 2.4.7.1 Forms of basal ganglia plasticity. 2.4.7.2 DA: principal mediator of plasticity in the basal ganglia. 2.4.7.3 Insights from plasticity within the hippocampus. 2.4.8 Initial reflections on the possible role of the basal ganglia in virtue acquisition. 2.5 Neural bases for emotional control. ……………………………………. 198 2.5.1 Theories of emotion. 2.5.2 Emotion and memory. 2.5.3 Human brain areas associated with emotion. 2.5.3.1 Involvement of cortical areas in emotional regulation. 2.5.4 Plasticity in the mechanisms of emotional regulation. 2.5.5 Development of attentional mechanisms. 2.6 Neural bases for goal directed behaviours and reward activation. ……………………………………………………………………………. 218 2.6.1 Reward pathways and motivation. 2.6.2 Classical conditioning and DA reinforcement. 2.6.3 Goal directed plasticity in the amygdala. 2.6.4 Reinforcement in basal ganglia learning. 2.6.4.1 DA modulation in striatum for goal directed action. 2.6.5 Frontal cortex and reward systems. 2.6.5.1 The role of the OFC. 2.6.5.2 Close alignment between OFC and striatum. 2.6.6 Addiction studies offer insights into the reward systems. 2.7. Cognition and executive function. ………………………………………. 241 2.7.1 The PFC coordinates executive function. 2.7.2 Functional studies of the PFC. 2.7.3 Prefrontal plasticity. 6 2.7.3.1 Plasticity studies in the motor cortices. 2.8 Conclusion. …………………………………………………………………………… 248 Chapter 3 Investigating the characteristics of virtue. 3.1 Dr Takashi Nagai (1908-1951). ……………………………………………… 259 3.1.1 Context: August 9, 1945. 3.1.2 Acts of virtue. a) Scenario 1. Treating a prisoner. b) Scenario 2. The Rising Sun. c) Scenario 3. The Pamphlet. d) Scenario 4. Nyokodo. 3.1.3 Virtue and the human act. 3.1.4 Some observations about the characteristics of virtue. 3.1.5 The superiority of virtue ethics in accounting for noble human behaviour. 3.2 The state of virtue. ………………………………………………………………. 282 3.2.1 Virtues dispose the appetites, the source of all human acts, to rationality. 3.2.1.1 The virtues of the sensitive appetite refine our habitual dispositions to pain and pleasure. 3.2.1.2 Virtue is a habit of choosing. 3.2.2 Virtue lies in choice of the mean. 3.2.3 The motivation of virtue. “Virtuous actions are done for the sake of the noble.” 3.2.4 Virtues bring about states of character. 3.2.5 Virtues accord with the natural perfecting of the person. 3.2.5.1 Virtue is pleasant. 3.2.5.2 “Happiness is the reward of virtue.” 3.2.5.3 Virtue brings about human fulfilment.