Moving faces, looking places: validation of the Amsterdam Dynamic Facial Expression Set (ADFES)

We report two studies validating a new standardized set of filmed emotion expressions, the Amsterdam Dynamic Facial Expression Set (ADFES). The ADFES is distinct from existing datasets in that it includes a face-forward version and two different head-turning versions (faces turning toward and away from viewers), North-European as well as Mediterranean models (male and female), and nine discrete emotions (joy, anger, fear, sadness, surprise, disgust, contempt, pride, and embarrassment). Study 1 showed that the ADFES received excellent recognition scores. Recognition was affected by social categorization of the model: displays of North-European models were better recognized by Dutch participants, suggesting an ingroup advantage. Head-turning did not affect recognition accuracy. Study 2 showed that participants more strongly perceived themselves to be the cause of the other's emotion when the model's face turned toward the respondents. The ADFES provides new avenues for research on emotion expression and is available for researchers upon request.     

Autonomy,decisions, and free will

Can humans make decisions? Can machines? What ethical questions arise from using robotics in the education of children? Or in elderly care? These were some of the topics of the interdisciplinary college (IK), which took place from the 25th of March to the 1st of April in Günne, next to Lake Möhne. During this one-week spring school, more than 40 well-known lecturers from around the globe gave 170 participants an insight into a cornucopia of topics surrounding “autonomy, decisions, and free will”.     

Does the name-race implicit association test measure racial prejudice?

Research using the Implicit Association Test (IAT) has shown that names labeled as Caucasian elicit more positive associations than names labeled as non-Caucasian. One interpretation of this result is that the IAT measures latent racial prejudice. An alternative explanation is that the result is due to differences in in-group/out-group membership. In this study, we conducted three different IATs: one with same-race Dutch names versus racially charged Moroccan names; one with same-race Dutch names versus racially neutral Finnish names; and one with Moroccan names versus Finnish names. Results showed equivalent effects for the Dutch-Moroccan and Dutch-Finnish IATs, but no effect for the Finnish-Moroccan IAT. This suggests that the name-race IAT-effect is not due to racial prejudice. A diffusion model decomposition indicated that the IAT-effects were caused by changes in speed of information accumulation, response conservativeness, and non-decision time.     

Recently inhibited responses are avoided for both masked and nonmasked primes in a spatial negative priming task

Responding to the location of a target is delayed when the target arises at a position previously occupied by a distractor (ignored-repetition trial), relative to when it occurs at a formerly unoccupied location (control trial) [i.e., the spatial negative priming (SNP) effect]. Speculation has held that recently inhibited (distractor) responses resist future execution (i.e., execution resistance [ER]), and thus cause SNP. Evidence for ER has been reported for identity-based tasks using masked prime distractor events. The purpose of this study was to examine the potential impact of ER on response selection in an SNP task for both nonmasked (traditional) and masked primes. We employed a modified SNP task that included nonmasked and masked target-only and distractor-only visual primes (first trial), along with forced choice and free choice probes (second trial). On free choice trials, a selection bias against the prime-distractor-assigned response was evident (same-hand competition, for both nonmasked and masked primes). This selection avoidance was held to reflect ER operating with inhibited prime distractor responses. Further, inhibitory aftereffect patterns were the same for nonmasked and masked distractor primes, and masking target primes transformed a positive to a negative aftereffect, as predicted by the self-inhibition model of mask function set out by Schlaghecken and Eimer (Psychonomic Bulletin & Review, 11, 463-468, 2004).     

Incongruence in number–luminance congruency effects

Congruency tasks have provided support for an amodal magnitude system for magnitudes that have a "spatial" character, but conflicting results have been obtained for magnitudes that do not (e.g., luminance). In this study, we extricated the factors that underlie these number-luminance congruency effects and tested alternative explanations: (unsigned) luminance contrast and saliency. When luminance had to be compared under specific task conditions, we revealed, for the first time, a true influence of number on luminance judgments: Darker stimuli were consistently associated with numerically larger stimuli. However, when number had to be compared, luminance contrast, not luminance, influenced number judgments. Apparently, associations exist between number and luminance, as well as luminance contrast, of which the latter is probably stronger. Therefore, similar tasks, comprising exactly the same stimuli, can lead to distinct interference effects.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Disengaging the negative priming mechanism in location tasks

In a location-based negative priming task, targets that appear at locations that were previously occupied by distractors are typically responded to more slowly than are targets that appear at formerly unoccupied positions. In the present study, we attempted to disengage the location-based negative priming mechanism by presenting visual cues indicating the most likely location of the upcoming target. The first experiment showed that 75% cue-target validity was not sufficient to affect the negative priming mechanism. However, the second experiment demonstrated that a much reduced, but not eliminated, negative priming effect occurred with 100%cue-target validity. These findings are similar to those found with inhibition of return, suggesting that location-based inhibition of return effects and location-based negative priming effects may share a common inhibition mechanism.     

Spatial negative priming modulation: The influence of probe-trial target cueing,distractor presence,and an intervening response

Reaction times are slower when a target (T) appears at a location that has just contained a distractor (D) (ignored-repetition trial), relative to when it arises at a previously unoccupied spatial position (control trial), i.e., the spatial negative priming (NP) effect. In a typical spatial NP paradigm trials are presented in pairs, first the prime and then the probe. Validly cueing ignored-repetition trials, and/or reducing probe distractor probability, modulated the NP process under certain conditions following target-plus-distractor (prime response) but not after distractor-only (no prime response) primes. This supported the idea that the production of a prime (intervening) response meets the needs for producing NP modulation. Additionally, NP elimination, evident when the probe was randomly distractor-free, was not seen when the probe also contained a distractor event. This suggests that the removal of the NP effect is likely achieved by blocking the retrieval of prime distractor information, rather than by removing the NP cause. Seemingly, the presence of a probe distractor is able to bypass the retrieval block.     

Lifelong reductions of PKMζ in ventral hippocampus of nonhuman primates exposed to early-life adversity due to unpredictable maternal care

Protein kinase Mζ (PKMζ) maintains long-term potentiation (LTP) and long-term memory through persistent increases in kinase expression. Early-life adversity is a precursor to adult mood and anxiety disorders, in part, through persistent disruption of emotional memory throughout life. Here we subjected 10- to 16-wk-old male bonnet macaques to adversity by a maternal variable-foraging demand paradigm. We then examined PKMζ expression in their ventral hippocampi as 7- to 12-yr-old adults. Quantitative immunohistochemistry reveals decreased PKMζ in dentate gyrus, CA1, and subiculum of subjects who had experienced early-life adversity due to the unpredictability of maternal care. Adult animals with persistent decrements of PKMζ in ventral hippocampus express timid rather than confrontational responses to a human intruder. Persistent down-regulation of PKMζ in the ventral hippocampus might reduce the capacity for emotional memory maintenance and contribute to the long-lasting emotional effects of early-life adversity.

Early-life adversity is associated with an increased vulnerability to stress-related disorders that is maintained into adulthood, suggesting a very long-lived effect on emotional memory by the early-life event (Coplan et al. 1996). Although several structural and neurochemical sequelae of early-life adversity have been reported (Teicher et al. 2003; Jackowski et al. 2011), the direct effects of early-life adversity on the molecular substrates maintaining long-term memory storage have not been explored.Accumulating evidence supports a crucial role for the autonomously active, atypical protein kinase C (PKC) isoform protein kinase Mζ (PKMζ) in maintaining synaptic long-term potentiation (LTP), a putative physical substrate for memory, and long-term memory storage (Ling et al. 2002; Pastalkova et al. 2006; Glanzman 2013; Sacktor and Fenton 2018). The autonomous activity of PKMζ is due to its unusual structure that differs from other PKC isoforms (Sacktor et al. 1993). Most PKCs consist of two domains: a catalytic domain and an autoinhibitory regulatory domain that suppresses the catalytic domain. Therefore, most PKCs are inactive until second messengers bind to the regulatory domain and induce a conformational change that releases the autoinhibition. Because second messengers that activate PKCs such as Ca²⁺ or diacylglycerol have short half-lives, most PKCs are only transiently activated.PKMζ, in contrast, consists of an independent PKCζ catalytic domain, and the absence of an autoinhibitory regulatory domain results in autonomous and thus persistent activity once the kinase is synthesized. PKMζ mRNA is transcribed from an internal promoter within the PKCζ/PKMζ gene that is active only in neural tissue (Hernandez et al. 2003). The mRNA is translationally repressed and transported to dendrites of neurons (Muslimov et al. 2004). High-frequency afferent synaptic activity during LTP induction or learning derepresses PKMζ mRNA translation, triggering new synthesis of PKMζ protein (Osten et al. 1996; Hernandez et al. 2003; Tsokas et al. 2016; Hsieh et al. 2017).Once increased, the steady-state amount of PKMζ remains elevated during LTP or long-term memory maintenance. Recent work with quantitative immunohistochemistry (IHC) shows that spatial conditioning induces persistent increases of PKMζ in somatic and selective dendritic compartments of dorsal hippocampal CA1 pyramidal cells that can last at least 1 mo (Hsieh et al. 2021). The persistent increases are preferentially expressed in CA1 pyramidal cells that were activated during the formation of the memory, specifically at the termination zone of the Schaffer collateral/commissural inputs from subfield CA3. In contrast, persistent PKMζ increases are not evident in stratum lacunosum-moleculare, the termination zone that originates in entorhinal cortex that nonetheless is capable of expressing PKMζ. Postsynaptic domain-specific PKMζ expression patterns hint at distinct circuit-specific modifications of cortical–hippocampal synaptic function by maturational and experiential factors.Persistent changes in PKMζ expression are also associated with changes in the capacity for learning and memory across the life span of animals. Decreased memory ability in aged rats is associated with decreased training-induced, persistent PKMζ expression in prelimbic cortex, and increases in PKMζ are crucial for the cognition-enhancing effects of environmental enrichment in the aged animals (Chen et al. 2016). Hara et al. extended the connection between PKMζ and cognitive function to nonhuman primates (NHPs), showing that levels of PKMζ expression in dentate gyrus (DG) axospinous synapses correlate with successful performance on cognitive tasks in young and aged monkeys (Hara et al. 2012). These studies suggest that persistent down-regulation of PKMζ may comprise an important pathophysiological mechanism for cognitive impairment.Here we used a validated NHP model of early-life adversity, maternal variable-foraging demand (VFD), to explore the links between adversity in infancy and PKMζ expression in adulthood (Coplan et al. 1996; Jackowski et al. 2011). Previous studies of the VFD paradigm have revealed that both infants and their mothers exposed to VFD show significant cerebrospinal fluid (CSF) elevations of the stress neuropeptide, corticotropin-releasing factor (CRF). Moreover, the magnitude of CRF change in mothers and infants are positively correlated, suggesting synchronization of maternal–infant stress responses to the VFD stressor (Coplan et al. 2005). From a behavioral standpoint, maternal social rank plays a negligible role in determining an aggregate score of maternal–infant proximity, suggesting preferential attention of mothers to their infants. During the VFD condition, maternal social rank predicts >80% of the variance of maternal–infant proximity, suggesting mothering patterns are interrupted by preferential orientations to social rank; the latter determines food accessibility (Coplan et al. 2015). Dominant females show relative increases in maternal–infant proximity, whereas subordinate females show relative reductions in maternal–infant proximity. Neither pattern of attachment ameliorates an abnormal association between CSF oxytocin concentrations and hypothalamic-pituitary-adrenal (HPA) axis activity (Coplan et al. 2015). Offspring exposed to VFD rearing assessed both as juveniles and as full adults demonstrate persistent increases in CSF CRF concentrations in comparison with controls reared under non-VFD conditions (Coplan et al. 1996, 2001).Our prior neurohistological studies pointed to the DG as a region particularly vulnerable to VFD exposure, as shown by reduced trophic signaling and neurogenesis (Jackowski et al. 2011; Perera et al. 2011; Schoenfeld et al. 2021). We therefore hypothesized that early-life adversity due to unpredictable maternal care (for brevity, subsequently referred to as “early-life adversity”) reduces the persistent expression of PKMζ within the DG of ventral intrahippocampal neurocircuitry that mediates affective memory processing (Fanselow and Dong 2010). We used PKMζ antisera validated by the lack of immunostaining in PKMζ-null mice (Hsieh et al. 2021) to examine PKMζ expression in ventral hippocampus (NHP anterior hippocampus) in both DG granule cell layer and the stratum moleculare of the suprapyramidal blade that receives direct input from entorhinal cortex, as well as other regions encompassing the hippocampal formation, including the hilus, CA3, CA1, and subiculum.To assess behavioral correlates of hippocampal PKMζ expression, we used a stress-inducing paradigm designed specifically for singly housed bonnet macaque male NHPs, which we refer to as the “human exposure response” (Jackowski et al. 2011; Hamel et al. 2017), which is a variation of the paradigm used in human exposure studies by Kalin et al. in rhesus macaques (Kalin and Shelton 1989). On exposure to a direct human presence, singly housed adult male bonnet macaques react with a dichotomy of responses—confrontational versus timid (see the Materials and Methods) (Jackowski et al. 2011). In our macaque colony, groups of fully adult males are necessarily housed individually to prevent injury sustained during male agonistic encounters, whereas adult females and/or juveniles are safely housed in social groups. Because group housing of nursing females and/or juveniles of both sexes elicits a range of behaviors intrinsic to the species’ social repertoire (Rosenblum et al. 2001; Coplan et al. 2015) that complicates behavioral analyses to human exposure, we restricted our current study to male macaques.