Does fear beget fear? Risk-mediated habitat selection triggers predator avoidance at lower trophic levels

Seasonal changes in weather and food availability differentially impact energy budgets of small mammals such as bats. While most thermal physiological research has focused on species that experience extreme seasonal temperature variations, knowledge is lacking from less variable temperate to subtropical climates. We quantified ambient temperature (T _a) and skin temperature (T _sk) responses by individuals from a population of New Zealand lesser short-tailed bats (Mystacina tuberculata) during summer and winter using temperature telemetry. During summer, communal roosts were more thermally stable than T _a. During winter, solitary roosts were warmer than T _a indicating significant thermal buffering. Communal roost trees were used on 83 % of observation days during summer, and individuals occupying them rarely entered torpor. Solitary roosts were occupied on 93 % of observation days during winter, and 100 % of individuals occupying them used torpor. During summer and winter, bats employed torpor on 11 and 95 % of observation days, respectively. Maximum torpor bout duration was 120.8 h and winter torpor bout duration correlated negatively with mean T _a. Torpor bout duration did not differ between sexes, although female minimum T _sk was significantly lower than males. The summer Heterothermy Index varied, and was also significantly affected by T _a. Mean arousal time was correlated with sunset time and arousals occurred most frequently on significantly warmer evenings, which are likely associated with an increased probability of foraging success. We provide the first evidence that torpor is used flexibly throughout the year by M. tuberculata, demonstrating that roost choice and season impact torpor patterns. Our results add to the growing knowledge that even small changes in seasonal climate can have large effects on the energy balance of small mammals.     

Auditory-evoked spike firing in the lateral amygdala and Pavlovian fear conditioning: mnemonic code or fear bias?

Amygdala neuroplasticity has emerged as a candidate substrate for Pavlovian fear memory. By this view, conditional stimulus (CS)-evoked activity represents a mnemonic code that initiates the expression of fear behaviors. However, a fear state may nonassociatively enhance sensory processing, biasing CS-evoked activity in amygdala neurons. Here we describe experiments that dissociate auditory CS-evoked spike firing in the lateral amygdala (LA) and both conditional fear behavior and LA excitability in rats. We found that the expression of conditional freezing and increased LA excitability was neither necessary nor sufficient for the expression of conditional increases in CS-evoked spike firing. Rather, conditioning-related changes in CS-evoked spike firing were solely determined by the associative history of the CS. Thus, our data support a model in which associative activity in the LA encodes fear memory and contributes to the expression of learned fear behaviors.     

Trace fear conditioning: a role for context?

Fear conditioning can be rapidly obtained over long trace intervals, but its specificity with respect to both time and stimulus is uncertain. Long-trace fear conditioning often parallels contextual conditioning, and it is sensitive to hippocampal lesions. These properties of trace conditioning are not directly addressed by timing models and multiple-time-scale models of conditioning. It is proposed that during early stages of conditioning, a joint representation of the context and the stimulus trace may underlie conditioned responses, and that discriminative processes allow the emergence of specific responses in a later stage.     

Love or fear: Can punishment promote cooperation?

Cooperation is a paradox: Why should one perform a costly behavior only to increase the fitness of another? Human societies, in which individuals cooperate with genetically unrelated individuals on a considerably larger scale than most mammals do, are especially puzzling in this regard. Recently, the threat of punishment has been given substantial attention as one of the mechanisms that could help sustain human cooperation in such situations. Nevertheless, using punishment to explain cooperation only leads to further questions: Why spend precious resources to penalize free‐riders, especially if others can avoid this investment and cheaters can punish you back? Here, it is argued that current evidence supports punishment as an efficient means for the maintenance of cooperation, and that the gravity of proposed limitations of punishment for maintaining cooperation may have been overestimated in previous studies due to the features of experimental design. Most notably, the importance of factors as characteristic of human societies as reputation and language has been greatly neglected. Ironically, it was largely the combination of the two that enabled humans to shape costly punishment into numerous low‐cost and less detrimental strategies that clearly can promote human cooperation.     

Technology and fear: is wonder the key?

Technology is a social practice that embodies the capacity of societies to transform themselves by creating and manipulating not only physical objects, but also symbols and cultural forms. It is an illusion that scientific and socioeconomic drivers are the sole elements determining the destiny of a technology. Although they are important, what is really crucial is the way in which a human community 'metabolizes' a new technology, that is the way in which a new technology becomes part of the mental landscape of people living in that society. In this paper I argue that today, fear of technology mainly emerges from a lack of meaning surrounding the technology revolution. Present technology is developing without a sound cultural framework that could give technology a sense beyond mere utilitarian considerations. Frightening stories then end up being a privileged way to incorporate technology into a meaningful context. However, fear is not the sole emotion that can enable integration of new concepts into mental schemes, two other powerful emotional forces should be considered: wonder and curiosity.     

Are fear memories made and maintained by the same NMDA receptor-dependent mechanisms?

A recent finding indicates that inducible knockout of the NR1 NMDA receptor subunit promotes the loss of fear memories formed months earlier. One view is that posttraining NMDA receptor activation protects modified synapses from "synaptic drift." An alternative view is that NMDA receptors help maintain appropriate connectivity in memory-encoding networks.     

Hippocampus and memory. Can we have our place and fear it too?

Theories of hippocampal function are often split into cognitive map theories and relational/episodic memory theories. In this issue of Neuron, show that hippocampal cells respond to the combination of spatial location and conditioned stimuli in a nonspatial fear conditioning task, suggesting a potential bridge between the competing theories of hippocampal function.     

Landscapes of fear or competition? Predation did not alter habitat choice by Arctic rodents

In systems where predation plays a key role in the dynamics of prey populations, such as in Arctic rodents, it is reasonable to assume that differential patterns of habitat use by prey species represent adaptive responses to spatial variation in predation. However, habitat selection by collared (Dicrostonyx groenlandicus) and brown (Lemmus trimucronatus) lemmings depends on intra- and inter-specific densities, and there has been little agreement on the respective influences of food abundance, predators, and competition for habitat on lemming dynamics. Thus, we investigated whether predation affected selection of sedge-meadow versus upland tundra by collared lemmings in the central Canadian Arctic. We first controlled for the effects of competition on lemming habitat selection. We then searched for an additional signal of predation by comparing habitat selection patterns between 12 control plots and one large grid where lemmings were protected from predators by fencing in 1996 and 1997, but not during 5 subsequent years when we monitored habitat use in the grid as well as in the control plots. Dicrostonyx used upland preferentially over meadows and was more numerous in 1996 and 2011 than in other sample years. Lemmus was also more abundant in 1996 than in subsequent years, but its abundance was too low in the exclosure to assess whether exclusion of predators influenced its habitat selection. Contrary to the effects of competition, predation had a negligible impact on the spatial dynamics of Dicrostonyx, at least during summer. These results suggest that any differences in predation risk between the two habitats have little direct influence on the temporal dynamics of Dicrostonyx even if induced through predator–prey cycles.     

Does conditioned taste aversion learning in the pond snail Lymnaea stagnalis produce conditioned fear?

In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.     

The politics of fear: what does it mean to those who are otherized and feared?

Islamophobia has, of late, created a tendency to conflate all Muslims as belonging to a single nation of Islam that does not recognize and respect boundaries imposed by western geopolitics. This has been done by some to create and by others to generate a sense of exclusive unity that would separate all Muslims and make them into ‘others’ within western societies. It is the contention of this paper that such calls both embody and ignore the diversities of Islam as understood and practised by its adherents. Furthermore by ‘otherizing’ the entire community of Muslims in the West, the singular label of ‘Islamism’ marginalizes and may even silence the vibrant contestations among Muslims about their faith and its teachings; these include questions posed by women who may be described as feminists. The attributes of Islamism, ascribed to the faith by public, the media and politicians in the West and adopted by some Muslims primarily as a politically unifying force, are very different from the fluidity and flexibility that has been a historic part of lived Islam. Many Muslims may well aspire to belong to the umma: people of Islam conceptualized as crossing ethnic, racial, geographical and political boundaries. But Muslims in general and Muslim women in particular do not wish to do so at the expense of being otherized and conforming to the negative stereotypes ascribed to them that mask their fluid identities and, in the case of ‘white’ women, their close ties with their kinship networks. The multiplicity of Muslim's identities sits more easily within the permeable unbounded umma applicable to the global as well as the local without necessarily always privileging one or other identity.     

Impact of pain,psychological-distress,SARS-CoV2 fear on adults’ OHRQOL during COVID-19 pandemic

Corona virus disease (COVID-19) has crippled life, families and oral health care delivery. Hence, we assessed the impact of dental pain, fear of COVID-19 and psychological distress during lockdown on the oral health related quality of life of individuals visiting a tertiary dental care center during COVID-19 pandemic. Cross sectional study conducted among patients between 18 and 60 years. Demographics, access to pain killers, dental care (yes/no), duration (</> 15 days) and intensity of pain were self reported. Fear of COVID-19 was assessed using fear of corona virus scale (FCV-19S); psychological distress in the last 30 days and oral health related quality of life was evaluated. Oral examination was performed and dental caries status (DMFT) was assessed using the world health organization method. Univariate and multivariate regression analysis was conducted to evaluate significant predictors and 5% was set as level of significance. 2966 patients visited our dental emergency due to painful decayed tooth between March-June 2020. Mean age was 42.7 years, 53.97% were males and most common cause of painful teeth was upper right third molar (7.7%). 73.4% reported lack of pain medication; 95% reported closure of dental clinics close to home. Almost 79% suffered from dental pain for >15 days. Higher self reported pain (OR 2.1; 95% CI 1.36–14.71), >15 days of suffering from pain (OR 6.8; 95% CI 2.18–23.14), greater fear of COVID-19 (OR 4.14; 95% CI 1.98–16.07) and psychological distress (OR 4.41; 95% CI 1.09–16.76) were associated with poorer OHRQOL of adults during COVID-19 pandemic. Our findings strongly suggest that COVID-19 pandemic negatively impacts the mental and oral health of individuals affecting their overall health.     

Are beta-adrenergic receptors in the hippocampal CA1 region required for retrieval of contextual fear memory?

It is well established that β-adrenoceptors (β-ARs) in the hippocampal CA1 region are involved in regulating synaptic plasticity and are essential for acquisition and consolidation of spatial memory and contextual fear memory. Previous studies reported that β-ARs in the CA1 region are also involved in memory retrieval. The present study re-examined the role of hippocampal β-ARs in retrieval of conditioned contextual fear. We bilaterally infused a high dose of the β-AR antagonist propranolol (15 μg in 1 μl saline) into the CA1 region 30 min before retention test and found that propranolol produced no deficit in retrieval of either 1-day or 7-day contextual fear. We then examined if β-AR stimulation would produce a beneficial effect. The β-AR agonist isoproterenol (10 μg in 1 μl saline) was infused into the CA1 region 30 min before retention test. Surprisingly, isoproterenol did not enhance but severely disrupted retrieval of 7-day contextual fear memory, with no impact on retrieval of 1-day contextual fear memory. The present study argues against the previous conclusion that β-ARs in the CA1 region play a role in memory retrieval. β-ARs in the CA1 region may be dispensable for retrieval of conditioned contextual fear.