Hippocampal Damage Increases Deontological Responses during Moral Decision Making

Abstract

Complex moral decision making is associated with the ventromedial prefrontal cortex (vmPFC) in humans, and damage to this region significantly increases the frequency of utilitarian judgments. Since the vmPFC has strong anatomical and functional links with the hippocampus, here we asked how patients with selective bilateral hippocampal damage would derive moral decisions on a classic moral dilemmas paradigm. We found that the patients approved of the utilitarian options significantly less often than control participants, favoring instead deontological responses—rejecting actions that harm even one person. Thus, patients with hippocampal damage have a strikingly opposite approach to moral decision making than vmPFC-lesioned patients. Skin-conductance data collected during the task showed increased emotional arousal in the hippocampal-damaged patients and they stated that their moral decisions were based on emotional instinct. By contrast, control participants made moral decisions based on the integration of an adverse emotional response to harming others, visualization of the consequences of one's action, and the rational re-evaluation of future benefits. This integration may be disturbed in patients with either hippocampal or vmPFC damage. Hippocampal lesions decreased the ability to visualize a scenario and its future consequences, which seemed to render the adverse emotional response overwhelmingly dominant. In patients with vmPFC damage, visualization might also be reduced alongside an inability to detect the adverse emotional response, leaving only the utilitarian option open. Overall, these results provide insights into the processes involved in moral decision making and highlight the complementary roles played by two closely connected brain regions.SIGNIFICANCE STATEMENT The ventromedial prefrontal cortex (vmPFC) is closely associated with the ability to make complex moral judgements. When this area is damaged, patients become more utilitarian (the ends justify the means) and have decreased emotional arousal during moral decision making. The vmPFC is closely connected with another brain region—the hippocampus. In this study we found that patients with selective bilateral hippocampal damage show a strikingly opposite response pattern to those with vmPFC damage when making moral judgements. They rejected harmful actions of any kind (thus their responses were deontological) and showed increased emotional arousal. These results provide new insights into the processes involved in moral decision making and highlight the complementary roles played by two closely connected brain regions.

Mind-wandering in people with hippocampal damage

“…All participants, including the patients, were able to provide accurate accounts of those experiments. Third, in previously-published studies involving the same patients and control participants using different paradigms, the patients were able to maintain information over time periods that were longer than those required for generating the current mind-wandering samples (McCormick et al, 2016(McCormick et al, , 2017a. Fourth, our sampling method did not involve any delay or distraction that might have affected the patients, nor did our protocol allow for increased post-hoc elaboration on the part of the control participants.…”

“…Six patients (all right-handed males, mean age 57.0 years (SD 16.9), age range 27 to 70) with selective bilateral hippocampal lesions and selective episodic memory impairment took part (see Tables 1 and 2 for demographic information and neuropsychological profiles). Of note, these patients were the same high-functioning individuals that took part in our previous studies (McCormick et al, 2016(McCormick et al, , 2017a. Hippocampal damage (see example in Fig.…”

Verbal paired associates and the hippocampus: The role of scenes

“…This impairment, which was not apparent for single objects, prompted the proposal of the scene construction theory which holds that scene imagery constructed by the hippocampus is a vital component of memory and other functions Maguire & Mullally, 2013). Findings over the last decade have since linked scenes to the hippocampus in relation to autobiographical memory but also widely across cognition, including perception (Graham et al, 2010;McCormick, Rosenthal, et al, 2017;Mullally et al, 2012), future-thinking (Hassabis, Kumaran, Vann, et al, 2007;Irish, Hodges, & Piguet, 2013;Schacter et al, 2012), spatial navigation (Clark & Maguire, 2016;Maguire, Nannery, & Spiers, 2006) and decision-making (McCormick, Rosenthal, Miller, & Maguire, 2016;Mullally & Maguire, 2014). However, as the current study was only designed to examine the role of the hippocampus in the VPA task, we do not speculate further here as to whether or not scene construction is the primary mechanism at play within the hippocampus.…”

Differences in functional connectivity along the anterior-posterior axis of human hippocampal subfields

“…The hippocampus has been implicated in supporting multiple cognitive functions including episodic memory (Scoville and Milner, 1957), the imagination of fictitious and future experiences (Hassabis et al, 2007;Addis et al, 2007), spatial navigation (Chersi and Burgess, 2015;Maguire et al, 2006), visual perception (Lee et al, 2012;McCormick et al, 2017;Mullally et al, 2012) mind-wandering Smallwood et al, 2016;Karapanagiotidis et al, 2016) and decision making (McCormick et al, 2016;Mullally et al, 2014). The hippocampus is a heterogenous structure comprising multiple subregions including the dentate gyrus (DG), cornu ammonis (CA) 1-4, prosubiculum, subiculum, presubiculum, parasubiculum and the uncus.…”