Does Ventromedial Prefrontal Cortex Damage Really Increase Impulsiveness? Delay and Probability Discounting in Patients with Focal Lesions.

If the tendency to discount rewards reflects individuals' general level of impulsiveness, then the discounting of delayed and probabilistic rewards should be negatively correlated: The less a person is able to wait for delayed rewards, the more they should take chances on receiving probabilistic rewards. It has been suggested that damage to the ventromedial prefrontal cortex (vMPFC) increases individuals' impulsiveness, but both intertemporal choice and risky choice have only recently been assayed in the same patients with vMPFC damage. Here, we assess both delay and probability discounting in individuals with vMPFC damage (n = 8) or with medial temporal lobe (MTL) damage (n = 10), and in age- and education-matched controls (n = 30). On average, MTL-lesioned individuals discounted delayed rewards at normal rates but discounted probabilistic rewards more shallowly than controls. In contrast, vMPFC-lesioned individuals discounted delayed rewards more steeply but probabilistic rewards more shallowly than controls. These results suggest that vMPFC lesions affect the weighting of reward amount relative to delay and certainty in opposite ways. Moreover, whereas MTL-lesioned individuals and controls showed typical, nonsignificant correlations between the discounting of delayed and probabilistic rewards, vMPFC-lesioned individuals showed a significant negative correlation, as would be expected if vMPFC damage increases impulsiveness more in some patients than in others. Although these results are consistent with the hypothesis that vMPFC plays a role in impulsiveness, it is unclear how they could be explained by a single mechanism governing valuation of both delayed and probabilistic rewards.

What relates newspaper, definite, and clothing? An article describing deficits in convergent problem solving and creativity following hippocampal damage.

Creativity relies on a diverse set of cognitive processes associated with distinct neural correlates, and one important aspect of creativity, divergent thinking, has been associated with the hippocampus. However, hippocampal contributions to another important aspect of creativity, convergent problem solving, have not been investigated. We tested the necessity of hippocampus for convergent problem solving using a neuropsychological method. Participants with amnesia due to hippocampal damage (N = 5) and healthy normal comparison participants (N = 5) were tested using a task that promoted solutions based on existing knowledge (Bowden and Jung-Beeman, 2003). During each trial, participants were given a list of three words (e.g., fly, man, place) and asked to respond with a word that could be combined with each of the three words (e.g., fire). The amnesic group produced significantly fewer correct responses than the healthy comparison group. These findings indicate that the hippocampus is necessary for normal convergent problem solving and that changes in the status of the hippocampus should affect convergent problem solving in the context of creative problem-solving across short intervals. This proposed contribution of the hippocampus to convergent problem solving is consistent with an expanded perspective on hippocampal function that acknowledges its role in cognitive processes beyond declarative memory. © 2016 Wiley Periodicals, Inc.

Moral judgment in episodic amnesia.

To investigate the role of episodic thought about the past and future in moral judgment, we administered a well-established moral judgment battery to individuals with hippocampal damage and deficits in episodic thought (insert Greene et al. 2001). Healthy controls select deontological answers in high-conflict moral scenarios more frequently when they vividly imagine themselves in the scenarios than when they imagine scenarios abstractly, at some personal remove. If this bias is mediated by episodic thought, individuals with deficits in episodic thought should not exhibit this effect. We report that individuals with deficits in episodic memory and future thought make moral judgments and exhibit the biasing effect of vivid, personal imaginings on moral judgment. These results strongly suggest that the biasing effect of vivid personal imagining on moral judgment is not due to episodic thought about the past and future. © 2016 Wiley Periodicals, Inc.

Specific, personally meaningful cues can benefit episodic prospection in medial temporal lobe amnesia.

OBJECTIVES: To determine whether severity of episodic prospection impairment in medial temporal lobe (MTL) amnesia is reduced by the types of cues that are used to elicit personal future episodes and, if so, whether episodic memory impairment is similarly affected. DESIGN: Multiple case study of five individuals with MTL amnesia and healthy control participants. METHODS: Participants were administered two tests of episodic prospection: A commonly used Galton-Crovitz task that uses generic cues (e.g., lemon) and a novel task that includes specific, personally meaningful cues referring to planned or plausible future events (e.g., granddaughter's recital). Narratives were scored for episodic detail using the Autobiographical Interview protocol (Levine et al., 2002), which distinguishes between internal (episodic) details and external (non-episodic) details. RESULTS: Results showed that specific, personally meaningful cues led to an appreciable reduction of episodic memory and prospection impairment in three of the amnesic cases tested. Clinical benefit from more structured, self-related cues may depend on factors such as extent of MTL damage or general severity of episodic memory and prospection impairment, highlighting the importance of methodological approaches to neuropsychological research that treat each case on an individual basis. CONCLUSIONS: In cases of mild-moderate amnesia, specific, personal cues afford more detailed episodic remembering and prospective imagining than individual cue words. PRACTITIONER POINTS: Previous reports of episodic prospection impairment in medial temporal lobe (MTL) amnesia might misrepresent an individual case's true prospective abilities Specific cues drawn from a patient's everyday life have greater ecological validity than the more typical generic cues used to elicit episodic prospection and can aid some individuals with MTL amnesia in the ability to imagine future experiences Assessment and rehabilitation tools for MTL amnesic populations should attempt to minimize broad, open-ended questions and instead provide more structured and personally meaningful cues to guide responses Further research is needed to determine case-specific characteristics that best predict benefit from specific, personal cues. These might include extent of MTL damage and overall severity of episodic memory and prospection impairment.

"Social" Neuroscience: Leveraging Social Media to Increase Student Engagement and Public Understanding of Neuroscience.

Neuroscience is young and still developing. It is quickly adapting to a number of emerging changes in science and education. Not only have neuroscientists been at the forefront of the open access publishing movement, but many prominent neuroscientists continue to push towards making science more accessible and understandable to the broader public. Social media is a global phenomenon that is changing the way that we talk about research and education. Researchers, students, and the public alike can leverage social media to find updates in research and higher education. Social media also provides pathways to connect with experts and non-experts in a way never been seen before. Two major trends are appearing in education and social media: 1) providing more engaging teaching activities, and 2) providing opportunities for community engagement using teaching activities that leverage social media. In this article, we describe a semester long teaching activity that challenged students to use social media in their learning process. We provide initial evaluation and feedback from the students on their social media experience in class, and suggestions for how to improve the project in future implementations.

The student as teacher: reflections on collaborative learning in a senior seminar.

A major influence on education since the 1950's has been Bloom's Taxonomy, a classification of learning objectives across multiple domains meant to educate the whole student (Anderson and Krathwohl, 2001). Although it has influenced educational pedagogy in primary education, higher education remains, in antiquity, heavily lecture based; viewing the instructor as an expert who professes their vast knowledge to their students. However, when students serve as instructor, it is difficult to apply this traditional view to the college classroom. Here we discuss the development, pedagogical approach, and experience of a senior level seminar course in which the students and instructor collaboratively explored an emerging field, embodied cognition, which combines research and theory from psychology and neuroscience among other disciplines, in which neither the students nor instructor were an expert. Students provided feedback and evaluations at three time points over the course of the semester, before class started, at midterm and at the end of the semester in order to address the experience and effectiveness of a collaborative seminar experience in which the instructor assumed a role closer to an equal of the students. Student responses revealed both high levels of satisfaction and degrees of perceived learning within the course at both the midterm and final evaluation. The approach of this seminar may be beneficial when applied to other seminars or course formats as students in this course felt as though they were learning more and appreciated being a more equal partner in their own learning process.

Hippocampal amnesia disrupts creative thinking.

Creativity requires the rapid combination and recombination of existing mental representations to create novel ideas and ways of thinking. The hippocampal system, through its interaction with neocortical storage sites, provides a relational database necessary for the creation, updating, maintenance, and juxtaposition of mental representations used in service of declarative memory. Given this functionality, we hypothesized that hippocampus would play a critical role in creative thinking. We examined creative thinking, as measured by verbal and figural forms of the torrance tests of creative thinking (TTCT), in a group of participants with hippocampal damage and severe declarative memory impairment as well as in a group of demographically matched healthy comparison participants. The patients with bilateral hippocampal damage performed significantly worse than comparison participants on both the verbal and figural portions of the TTCT. These findings suggest that hippocampus plays a role critical in creative thinking, adding to a growing body of work pointing to the diverse ways the hallmark processing features of hippocampus serve a variety of behaviors that require flexible cognition.

The effect of repetition on pronoun resolution in patients with memory impairment.

Referring to things in the world - that woman, her idea, she - is a central component of language. Understanding reference requires the listener to keep track of the unfolding discourse history while integrating multiple sources of information to interpret the speech stream as it unfolds in time. Pronouns are a common way to establish reference. But due to their impoverished form, to understand them listeners must relate features of the pronoun (e.g., gender, animacy) with existing representations of potential discourse referents. Successful referential processing seems to place demands on memory. In a previous study, patients with hippocampal amnesia and healthy participants listened to short stories as their eye movements were monitored. When interpreting ambiguous pronouns, healthy participants demonstrated order-of-mention effects, whereby ambiguous pronouns are interpreted as referring to the first-mentioned referent in the story. By contrast, memory-impaired patients exhibited significant disruptions in their ability to use information about which character had been mentioned first to interpret pronouns. Repetition of the most salient information is a common clinical recommendation for improving pronoun resolution and communication in individuals with memory disorders (e.g., Alzheimer's disease) but this recommendation lacks an evidentiary basis. The present study seeks to determine whether the pronoun resolution performance of hippocampal patients can be improved, by repetition of the target referent, increasing its salience. Results indicate that patients with hippocampal damage demonstrate improved processing of pronouns following repetition of the target referent, but benefit from this repetition to a significantly smaller degree compared to healthy participants. These results provide further evidence for the role of the hippocampal-dependent memory system in language processing and point to the need for empirically tested communication interventions.

Narrative construction is intact in episodic amnesia.

Autobiographical remembering and future imagining overlap in their underlying psychological and neurological mechanisms. The hippocampus and surrounding regions within the medial temporal lobes (MTL), known for their role in forming and maintaining autobiographical episodic memories, are also thought to play an essential role in fictitious and future constructions. Amnesic individuals with bilateral hippocampal damage cannot reconstruct their past personal experiences and also have severe deficits in the ability to construct coherent fictitious or future narratives. However, it is not known whether this impairment reflects a failure to generate details from autobiographical episodic memory to populate personal narratives or an inability to bind such details into coherent narratives. We show that four individuals with hippocampal damage and episodic amnesia can construct narratives when the relevant details of the story are provided in a picture book and that their narratives maintain overall coherence on several measures. These findings indicate that individuals with hippocampal damage can bind details into coherent narratives when details are available to them. We conclude that the hippocampal system instead likely plays a role in the generation of details from which narratives are constructed.

A new method for assessing the impact of medial temporal lobe amnesia on the characteristics of generated autobiographical events.

Constructing autobiographical events involves an initial phase of event selection, in which a memory or imagined future event is initially brought to mind, followed by a phase of elaboration, in which an individual accesses detailed knowledge specific to the event. While considerable research demonstrates the importance of the medial temporal lobes (MTL) in the later phase, its role in initial event selection is unknown. The present study is the first to investigate the role of the MTL in event selection by assessing whether individuals with MTL lesions select qualitatively different events for remembering and imagining than matched control participants. To do so, we created "event captions" that reflected the type of events selected for an autobiographical event narrative task by four individuals with MTL amnesia and control counterparts. Over 450 online raters assessed these event captions on qualitative dimensions known to vary with autobiographical recall (frequency, significance, emotionality, imageability, and uniqueness). Our critical finding was that individuals with MTL amnesia were more prone to select events that were rated as more frequently occurring than healthy control participants. We interpret this finding as evidence that people with impaired episodic memory from MTL damage compensate for their compromised ability to recall detailed information by relying more heavily on semantic memory processes to select generalized events. We discuss the implications for theoretical models of memory and methodological approaches to studying autobiographical memory.

Differential contributions of hippocampus and medial prefrontal cortex to self-projection and self-referential processing.

Converging evidence points to a neural network that supports a range of abilities including remembering the past, thinking about the future, and introspecting about oneself and others. Neuroimaging studies find hippocampal activation during event construction tasks, and patients with hippocampal amnesia are impaired in their ability to (re)construct events of the past and the future. Neuroimaging studies of constructed experiences similarly implicate the medial prefrontal cortex (mPFC), but it remains unknown whether the mPFC is critical for such processes. The current study compares performance of five patients with bilateral mPFC damage, six patients with bilateral hippocampal damage, and demographically matched comparison participants on an event construction task. Participants were given a neutral cue word and asked to (re)construct events across four time conditions: real past, imagined past, imagined present, and future. These event narratives were analyzed for the number of internal and external details to quantify the extent of episodic (re)experiencing. Given the literature on the involvement of the mPFC in self-referential processing, we also analyzed the event narratives for self-references. The patients with mPFC damage did not differ from healthy comparison participants in their ability to construct highly detailed episodic events across time periods but displayed disruptions in their incorporation of the self. Patients with hippocampal damage showed the opposite pattern; they were impaired in their ability to construct highly detailed episodic events across time periods but not in their incorporation of the self. The results suggest differential contributions of hippocampus and medial prefrontal cortex to the distributed neural network for various forms of self-projection.

The Aging Neighborhood: Phonological Density in Naming.

Aging affects the ability to retrieve words for production, despite maintainence of lexical knowledge. In this study, we investigate the influence of lexical variables on picture naming accuracy and latency in adults ranging in age from 22 to 86 years. In particular, we explored the influence of phonological neighborhood density, which has been shown to exert competitive effects on word recognition, but to facilitate word production, a finding with implications for models of the lexicon. Naming responses were slower and less accurate for older participants, as expected. Target frequency also played a strong role, with facilitative frequency effects becoming stronger with age. Neighborhood density interacted with age, such that naming was slower for high-density than low-density items, but only for older subjects. Explaining this finding within an interactive activation model suggests that, as we age, the ability of activated neighbors to facilitate target production diminishes, while their activation puts them in competition with the target.

The role of ventromedial prefrontal cortex in text comprehension inferences: semantic coherence or socio-emotional perspective?

Two hypotheses about the role of the ventromedial prefrontal cortex (vmPFC) in narrative comprehension inferences, global semantic coherence versus socio-emotional perspective, were tested. Seven patients with vmPFC lesions and seven demographically matched healthy comparison participants read short narratives. Using the consistency paradigm, narratives required participants to make either an emotional or visuo-spatial inference, in which a target sentence provided consistent or inconsistent information with a previous emotional state of a character or a visuo-spatial location of an object. Healthy comparison participants made the inferences both for spatial and emotional stories, as shown by longer reading times for inconsistent critical sentences. For patients with vmPFC lesions, inconsistent sentences were read slower in the spatial stories, but not in the emotional ones. This pattern of results is compatible with the hypothesis that vmPFC contributes to narrative comprehension by supporting inferences about socio-emotional aspects of verbally described situations.

Hippocampal contributions to language: evidence of referential processing deficits in amnesia.

A growing body of work suggests the hippocampus contributes to a variety of cognitive domains beyond its traditional role in memory. We propose that the hippocampus, in its capacity for relational binding, representational flexibility, and online maintenance and integration of multimodal relational representations, is a key contributor to language processing. Here we test the hypothesis that the online interpretation of pronouns is hippocampus-dependent. We combined eye tracking with neuropsychological methods, where participants (4 patients with bilateral hippocampal damage and severe declarative memory impairment, 4 patients with ventromedial prefrontal cortex [vmPFC] damage, and healthy comparison participants) viewed a scene while listening to short dialogues introducing 2 characters; for example, Melissa is playing violin for Debbie/Danny as the sun is shining overhead. She is wearing a blue/purple dress. Consistent with previous work, analysis of eye gaze showed that younger and older healthy comparison participants and the vmPFC patients rapidly identified the intended referent of the pronoun when gender uniquely identified the referent, and when it did not, they showed a preference to interpret the pronoun as referring to the first-mentioned character. By contrast, hippocampal patients, while exhibiting a similar gender effect, exhibited significant disruptions in their ability to use information about which character had been mentioned first to interpret the pronoun. This finding suggests that the hippocampus plays a role in maintaining and integrating information even over a very short discourse history. These observed disruptions in referential processing demonstrate how promiscuously the hallmark processing features of the hippocampus are used in service of a variety of cognitive domains including language.

Intact discourse cohesion and coherence following bilateral ventromedial prefrontal cortex.

Discourse cohesion and coherence give communication its continuity providing the grammatical and lexical links that hold an utterance or text together and give it meaning. Researchers often link cohesion and coherence deficits to the frontal lobes by drawing attention to frontal lobe dysfunction in populations where discourse cohesion and coherence deficits are reported and through attribution of these deficits to underlying cognitive impairments putatively associated with the frontal lobes. We examined the distinct contribution of a region of the frontal lobes, the ventromedial prefrontal cortex (vmPFC), to discourse cohesion and coherence across a range of discourse tasks. We found that bilateral vmPFC damage does not impair cohesion and coherence in spoken discourse. This study provides insights into the contribution of the major anatomical subdivisions of the frontal lobes to language use and furthers our understanding of the neural and cognitive underpinnings of discourse cohesion and coherence.

Cohesion, coherence, and declarative memory: Discourse patterns in individuals with hippocampal amnesia.

BACKGROUND: Discourse cohesion and coherence gives our communication continuity. Deficits in cohesion and coherence have been reported in patients with cognitive-communication disorders (e.g., TBI, dementia). However, the diffuse nature of pathology and widespread cognitive deficits of these disorders have made identification of specific neural substrates and cognitive systems critical for cohesion and coherence challenging. AIMS: Taking advantage of a rare patient group with selective and severe declarative memory impairments, the current study attempts to isolate the contribution of declarative memory to the successful use of cohesion and coherence in discourse. METHODS #ENTITYSTARTX00026; PROCEDURES: Cohesion and coherence were examined in the discourse of six participants with hippocampal amnesia and six demographically matched comparison participants. Specifically, this study (1) documents the frequency, type, and completeness of cohesive ties; (2) evaluates discourse for local and global coherence; and (3) compares use of cohesive ties and coherence ratings in amnesia and healthy participants. OUTCOMES #ENTITYSTARTX00026; RESULTS: Overall, amnesia participants produced fewer cohesive ties per T-unit, the adequacy of their ties were more often judged to be incomplete, and the ratings of their local coherence were consistently lower than comparison participants. CONCLUSIONS: These findings suggest that declarative memory may contribute to the discursive use of cohesion and coherence. Broader notions of cohesion, or interactional cohesion, i.e., cohesion across speakers (two or more people), time (days, weeks), and communicative resources (gesture), warrant further study as the experimental tasks used in the literature, and here, may actually underestimate or overestimate the extent of impairment.