Habituation Task Research Articles

Auditory EEG Biomarkers in Fragile X Syndrome: Clinical Relevance.

Sensory hypersensitivities are common and distressing features of Fragile X Syndrome (FXS). While there are many drug interventions that reduce behavioral deficits in Fmr1 mice and efforts to translate these preclinical breakthroughs into clinical trials for FXS, evidence-based clinical interventions are almost non-existent potentially due to lack of valid neural biomarkers. Local circuit function in sensory networks is dependent on the dynamic balance of activity in inhibitory/excitatory synapses. Studies are needed to examine the association of electrophysiological alterations in neural systems with sensory and other clinical features of FXS to establish their clinical relevance. Adolescents and adults with FXS (n = 38, Mean age = 25.5, std = 10.1; 13 females) and age matched typically developing controls (n = 40, Mean age = 27.7, std = 12.1; 17 females) completed auditory chirp and auditory habituation tasks while undergoing dense array electroencephalography (EEG). Amplitude, latency, and percent change (habituation) in N1 and P2 event-related potential (ERP) components were characterized for the habituation task; time-frequency calculations using Morlet wavelets characterized phase-locking and single trial power for the habituation and chirp tasks. FXS patients showed increased amplitude but some evidence for reduced habituation of the N1 ERP, and reduced phase-locking in the low and high gamma frequency range and increased low gamma power to the chirp stimulus. FXS showed increased theta power in both tasks. While the habituation finding was weaker than previously found, the remaining findings replicate our previous work in a new sample of patients with FXS. Females showed less deficit in the chirp task but not the habituation task. Abnormal increases in gamma power were related to more severe behavioral and psychiatric features as well as reductions in neurocognitive abilities. Replicating electrophysiological deficits in a new group of patients using different EEG equipment at a new data collection site with differing levels of environmental noise that were robust to data processing techniques utilizing multiple researchers, indicates a potential for scalability to multi-site clinical trials. Given the robust replicability, relevance to clinical measures, and preclinical evidence for sensitivity of these EEG measures to pharmacological intervention, the observed abnormalities may provide novel translational markers of target engagement and potentially outcome measures in large-scale studies evaluating new treatments targeting neural hyperexcitability in FXS.

Components in the P300: Don't forget the Novelty P3!

This study investigated stimulus-response patterns of temporal principal components analysis (PCA)-derived event-related potential (ERP) components in a classical auditory habituation paradigm with long interstimulus intervals. The skin conductance response (SCR) was included as the "gold standard" model of the Orienting Reflex. Thirty participants were presented with a single series of 10 identical 60dB tones, followed by a change trial at a different frequency. Single-trial, electrooculography-corrected ERPs were submitted to temporal PCA. The main focus was on the components expected in the P300/Late Positive Complex (LPC), and their electromagnetic tomography-derived cortical sources. Nine components were identified between 90 and 470ms poststimulus (in temporal order): three N1 subcomponents, P2, four LPC components, and a negative Slow Wave (SW). The expected order of P3a, P3b, Novelty P3 (nP3), and positive Slow Wave (+SW) in the LPC was confirmed. SCR demonstrated strong exponential decay and recovery. P3b and nP3 each showed exponential decrement over trials, but only nP3 showed recovery at the change trial. Novelty effects failed to reach significance for the other LPC components, and were not apparent in non-LPC components. Frontal lobe activity in Brodmann areas 6, 8, and 9 was common to P3a, P3b, nP3, and+SW, consistent with the functional integration of these components in the LPC. Individual components had specific sources, although some sources overlapped between components or were reactivated later in the LPC. These data provide a fresh perspective on the components of the LPC and their cortical sources, and offer a processing model for the P300 in a habituation task, potentially generalizable to other paradigms.

Object exploration facilitates 4-month-olds' mental rotation performance.

How do infants learn to mentally rotate objects, to imagine them rotating through different viewpoints? One possibility is that development of infants’ mental rotation (MR) is facilitated by visual and manual experience with complex objects. To evaluate this possibility, eighty 4-month-olds (40 females, 40 males) participated in an object exploration task with Velcro “sticky mittens” that allow infants too young to grasp objects themselves to nonetheless explore those objects manually as well as visually. These eighty infants also participated in a visual habituation task designed to test MR. Half the infants (Mittens First group) explored the object prior to the MR task, and the other half afterwards (Mittens Second group), to examine the role of immediate prior object experience on MR performance. We compared performance of male and female infants, but found little evidence for sex differences. However, we found an important effect of object exploration: The infants in the Mittens First group who exhibited the highest levels of spontaneous object engagement showed the strongest evidence of MR, but there were no consistent correlations between these measures for infants in the Mittens Second group. These findings suggest an important contribution from object experience to development of MR.

Adults’ Sex Difference in a Dynamic Mental Rotation Task

Abstract. With the Mental Rotation Test (MRT), large and reliable sex differences are found. Used with children younger than about 9 or 10 years, MRT performance is at chance level. Simpler tasks used with younger children have revealed inconclusive results. Moore and Johnson (2008 , 2011 ) observed sex differences in infants using a habituation task with 3D cube figures rotating back and forth in depth through a 240° angle. Thereafter, female infants treated similarly the original figure and a mirror-image cube figure presented revolving through the previously unseen 120° angle, whereas male infants behaved as if they recognized the familiar object. In the present study, 256 adults participated in the MRT as well as in a modified two-alternative forced-choice dynamic version of the infants’ task. Sex differences were present for both tasks. More importantly, there was a positive correlation in performance across both tasks for both women and men. Since the new task turned out to be simpler, it might be suitable also for children. We present the first, although indirect, evidence that the sex effects reported by Moore and Johnson might indeed reflect early sex differences in mental rotation.

INVOLVEMENT OF NEUROINFLAMMATION IN THE MEMORY OF ADULT AND OLD OFFSPRING FROM WISTAR RATS WITH FOLIC ACID DEFICIENCY OR SUPPLEMENTATION DURING PREGNANCY

The deficiency or supplementation of folic acid (FA) during the pregnancy can interfere in aging process. Therefore, the aim of the present study was to assess the impact of maternal deficiency and supplementation of AF on memory and neuroinflammation in the adult and old offspring of Wistar rats. Female and male Wistar rats were used for mating. After, the female rats pregnant remained for 28 days of pregnancy with different diets: AIN 93 diet or control, FA deficiency diet, AIN 93 diet + FA 5 mg/kg, AIN 93 diet + FA 10 mg/kg and AIN 93 diet + FA 50 mg/kg. The young adult (2-month-old) female offspring of all experimental groups and only the older (18-month-old) female offspring of rats with AIN 93 diet, FA deficiency diet and AIN 93 diet + AF 10mg/kg were subjected to open field habituation task and Y maze test and analyze of brain cytokine levels. The results show that the deficiency of FA and high supplementation (50 mg/kg) on the gestational period induced cognitive deficit in adult offspring. In the older, the control and FA deficiency group also showed damage. However, the FA 10 mg/kg group showed protection against this effect. It was observed that TNF-α and IL-β levels were increased in the hippocampus of 18-month-old offspring of control and FA deficiency group, and FA 10 mg/kg reversed this effect. The 2-month-old offspring of FA 50 mg/kg group showed reduction of IL-β level. Moreover, in the frontal cortex, it was observed that in adult offspring of FA 10 mg/kg group showed increase of IL-4 and FA 50 mg/kg induced reduction this cytokine. In the old animals was observed reduction of IL-4 level in the control group and increase in the FA 10 mg/kg group. In the hippocampus, the IL-4 levels of the adult offspring of FA deficiency and FA 50 mg/kg group were reduced. The adult offspring of FA 10 mg/kg group presented increase of IL-4 levels. Altogether, the results indicated that FA supplementation during pregnancy can protect the old offspring against the cognitive damage of aging, at least in part, by modulating inflammation.

Chaotic home environment is associated with reduced infant processing speed under high task demands

Early adversity has profound long-term consequences for child development across domains. The effects of early adversity on structural and functional brain development were shown for infants under 12 months of life. However, the causal mechanisms of these effects remain relatively unexplored. Using a visual habituation task we investigated whether chaotic home environment may affect processing speed in 5.5 month-old infants (n=71). We found detrimental effects of chaos on processing speed for complex but not for simple visual stimuli. No effects of socio-economic status on infant processing speed were found although the sample was predominantly middle class.Our results indicate that chaotic early environment may adversely affect processing speed in early infancy, but only when greater cognitive resources need to be deployed. The study highlights an attractive avenue for research on the mechanisms linking home environment with the development of attention control.

Verapamil Parameter- and Dose-Dependently Impairs Memory Consolidation in Open Field Habituation Task in Rats.

The purpose of the present study was to examine the effects of the phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, verapamil (1.0, 2.5, 5.0, or 10 mg/kg i.p.), administered immediately after the acquisition task, on memory consolidation of the open field habituation task, in male Wistar rats. On the 48 h retested trial, all tested parameters (ambulation in the side wall and in the central areas, number of rearing, time spent grooming and defecation rate) significantly decreased in the saline treated animals. A significant decrease of rearing was observed in all verapamil treated groups. On the retention day, the ambulation in the side wall and central areas significantly decreased in the animals treated with 1 mg/kg and 10 mg/kg of verapamil, while the time spent grooming and the defecation rate significantly decreased only in the group treated with 1 mg/kg of verapamil. According to the change ratio scores that correct the individual behavioral baseline differences during initial and final sessions, habituation deficit was found in animals treated with verapamil as follows: ambulation along the side wall area (1, 2.5, and 5 mg/kg), number of rearing (all used dose) and time spent grooming (2.5, 5, and 10 mg/kg). In conclusion, the present data suggest that the post-training administration of verapamil, parameter- and dose-dependently, impairs the habituation to a novel environment.

Prenatal DHA supplementation and infant attention.

Results of randomized trials on the effects of prenatal docosahexaenoic acid (DHA) on infant cognition are mixed, but most trials have used global standardized outcomes, which may not be sensitive to effects of DHA on specific cognitive domains. Women were randomized to 600 mg/d DHA or a placebo for the last two trimesters of pregnancy. Infants of these mothers were then followed on tests of visual habituation at 4, 6, and 9 mo of age. DHA supplementation did not affect look duration or habituation parameters but infants of supplemented mothers maintained high levels of sustained attention (SA) across the first year; SA declined for the placebo group. The supplemented group also showed significantly reduced attrition on habituation tasks, especially at 6 and 9 mo. The findings support with the suggestion that prenatal DHA may positively affect infants' attention and regulation of state.

The Relationship between Sitting and the Use of Symmetry As a Cue to Figure-Ground Assignment in 6.5-Month-Old Infants.

Two experiments examined the relationship between emerging sitting ability and sensitivity to symmetry as a cue to figure-ground (FG) assignment in 6.5-month-old infants (N = 80). In each experiment, infants who could sit unassisted (as indicated by parental report in Experiment 1 and by an in-lab assessment in Experiment 2) exhibited sensitivity to symmetry as a cue to FG assignment, whereas non-sitting infants did not. Experiment 2 further revealed that sensitivity to this cue is not related to general cognitive abilities as indexed using a non-related visual habituation task. Results demonstrate an important relationship between motor development and visual perception and further suggest that the achievement of important motor milestones such as stable sitting may be related to qualitative changes in sensitivity to monocular depth assignment cues such as symmetry.

Behavioral alterations induced by repeated saxitoxin exposure in drinking water.

BackgroundBlooms of the saxitoxin-producing cyanobacterium Cylindrospermopsis raciborskii have been contaminating drinking water reservoirs in Brazil for many years. Although acute effects of saxitoxin intoxication are well known, chronic deleterious outcomes caused by repeated saxitoxin exposure still require further investigation. The aim of the present work is to investigate the effects of consumption of drinking water contaminated with C. raciborskii for 30 days on learning and memory processes in rats.MethodsThe effects of saxitoxin (3 or 9 μg/L STX equivalents) or cyanobacteria on behavior was determined using the open field habituation task, elevated plus maze anxiety model task, inhibitory avoidance task, and referential Morris water maze task.ResultsNo effects of saxitoxin consumption was observed on anxiety and motor exploratory parameters in the elevated plus maze and open field habituation tasks, respectively. However, groups treated with 9 μg/L STX equivalents displayed a decreased memory performance in the inhibitory avoidance and Morris water maze tasks.ConclusionsThese results suggest an amnesic effect of saxitoxin on aversive and spatial memories.

Assessment of Smartphone Technology to Measure Electrodermal Activity: A validation study

Event Abstract Back to Event Assessment of Smartphone Technology to Measure Electrodermal Activity: A validation study Lisa Lole1*, Alex M. Russell1, Raven Wolfram1, Amida Dean1 and Nerilee Hing1 1 Central Queensland University, Australia Aim: Measuring electrodermal activity (EDA) both in laboratory settings and in the field usually requires the use of sophisticated and costly recording equipment. The current study sought to examine whether EDA data recorded with a new Smartphone application and associated recording device would produce comparable results to those obtained by traditional laboratory-based equipment. Methods EDA was simultaneously recorded using the smartphone application, eSense (Mindfield Biosystems Ltd) and ProComp Infiniti (Thought Technology Ltd) while participants (n = 20) completed a number of tasks. After a resting baseline was recorded, participants engaged in a light exercise task, a deep breathing relaxation task, a visual discrimination task, an auditory habituation task, and a complex cognitive processing task. Results: A fairly strong correlation was found between the data obtained using the eSense smartphone application and data recorded using the ProComp Infiniti recording device, r(19) = .85, p < .000. While the general EDA trace appeared to be comparable between the two devices, the main factor contributing to the lack of a strong correlation between the two pieces of equipment appeared to be a slight time lag in the eSense recording application. Conclusions: The results of the current study showed reasonable success of the eSense smartphone application to be used in research settings. Further development of the application and equipment could greatly benefit EDA research by providing a low-cost and portable way of measuring EDA either in a laboratory or in the field. Keywords: Electrodermal activity, smartphone, Validation, Smartphone application, skin conductance level Conference: ASP2016 - The 26th Annual Meeting of the Australasian Society for Psychophysiology, Adelaide Australia, Adelaide,SA, Australia, 12 Dec - 14 Dec, 2016. Presentation Type: Poster Presentation Topic: Abstract (student award) Citation: Lole L, Russell AM, Wolfram R, Dean A and Hing N (2016). Assessment of Smartphone Technology to Measure Electrodermal Activity: A validation study. Conference Abstract: ASP2016 - The 26th Annual Meeting of the Australasian Society for Psychophysiology, Adelaide Australia. doi: 10.3389/conf.fnhum.2016.221.00007 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Nov 2016; Published Online: 05 Dec 2016. * Correspondence: Dr. Lisa Lole, Central Queensland University, Bundaberg, Australia, l.lole@cqu.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lisa Lole Alex M Russell Raven Wolfram Amida Dean Nerilee Hing Google Lisa Lole Alex M Russell Raven Wolfram Amida Dean Nerilee Hing Google Scholar Lisa Lole Alex M Russell Raven Wolfram Amida Dean Nerilee Hing PubMed Lisa Lole Alex M Russell Raven Wolfram Amida Dean Nerilee Hing Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Dropout in looking time studies: The role of infants’ temperament and cognitive developmental status

Dropout of infants in looking time studies sometimes occurs at high rates, raising concerns that the representativeness of the final sample might be reduced in comparison to the originally obtained sample. The current study investigated which infant characteristics play a role in dropout. Infants were presented with a preferential looking task at 6 and 9 months of age. At 9 months of age, an additional habituation task and a subsequent novelty preference task were conducted. In addition, temperament was assessed via the Infant Behavior Questionnaire – Revised (IBQ-R, Gartstein & Rothbart, 2003), and cognitive developmental status was assessed via the Cognitive Scale of the Bayley Scale of Infant and Toddler Development (BSID-III, Bayley, 2006). Dropout was positively related to the IBQ-R temperament scales Distress to Limitations and Approach, and negatively related to the scales Falling Reactivity and Cuddliness. The representativeness of the final sample regarding situation-specific temperament dimensions is affected by dropout. Dropout was not related to cognitive developmental status as measured via the BSID-III, habituation speed and novelty preference. Dropout at 6 months of age was associated with dropout at 9 months of age. We concluded that in looking time studies, the representativeness of the final sample regarding performance-relevant temperament dimensions or cognitive developmental status is not affected by dropout.

Limitations of a habituation task to demonstrate discrimination of natural signals in songbirds

The habituation–dishabituation (HDH) paradigm is a common method used to examine animal cognition. Recent studies reported that spontaneous vocalizations could be used as an index of song familiarity and novelty in songbirds. However, these studies assigned only a few stimulus sets for all subjects, which might cause pseudoreplication. Therefore, we examined universality and general applicability of this method in Bengalese finches using a variety of stimulus sets. Seven unfamiliar conspecific songs were collected as a stimulus pool and a habituation song was randomly chosen for each subject. The subject was exposed to the habituation song repeatedly over 2h. During the test phase, the habituation song and a novel song randomly chosen from the stimulus pool were presented. We compared the degree of increase in call production during playback of those two songs. Although the degree was greater for the novel song compared with the habituation song in some birds, the trend was not consistent across all stimulus sets tested in these birds. Our results show that the HDH paradigm is not suitable to test song discrimination in songbirds unless precautions are taken to increase external validity by utilizing a variety of stimulus sets for each subject.

Signal clarity: an account of the variability in infant quantity discrimination tasks.

Infants have shown variable success in quantity comparison tasks, with infants of a given age sometimes successfully discriminating numerical differences at a 2:3 ratio but requiring 1:2 and even 1:4 ratios of change at other times. The current explanations for these variable results include the two-systems proposal - a theoretical framework that suggests that there are multiple systems at play and that these systems do not communicate early in infancy, leading to failure in certain numerical comparisons. An alternative proposal is that infants may be attending to continuous extent dimensions in these tasks rather than number per se. However, neither of these two main proposals is independently capable of accounting for the previously published data. Recently the Signal Clarity Hypothesis was proposed to account for and predict the variability (Cantrell & Smith, 2013). According to this hypothesis, infants' variable success may be understood from a framework of statistical learning taken together with the signal-to-noise ratio generated by control procedures in habituation tasks. Here we test specific predictions made by the Signal Clarity Hypothesis. Across four experiments assessing 9-month old discriminations of small and large sets (2 vs. 4 and 3 vs. 4), we demonstrate that infant success can be predicted by this novel approach and, further, that infants may discriminate smaller ratios of change than previously believed (3:4 numerical change and 2:3 cumulative area change).

Aberrant face and gaze habituation in fragile x syndrome.

The authors sought to investigate neural system habituation to face and eye gaze in fragile X syndrome, a disorder characterized by eye-gaze aversion, among other social and cognitive deficits. Participants (ages 15-25 years) were 30 individuals with fragile X syndrome (females, N=14) and a comparison group of 25 individuals without fragile X syndrome (females, N=12) matched for general cognitive ability and autism symptoms. Functional MRI (fMRI) was used to assess brain activation during a gaze habituation task. Participants viewed repeated presentations of four unique faces with either direct or averted eye gaze and judged the direction of eye gaze. Four participants (males, N=4/4; fragile X syndrome, N=3) were excluded because of excessive head motion during fMRI scanning. Behavioral performance did not differ between the groups. Less neural habituation (and significant sensitization) in the fragile X syndrome group was found in the cingulate gyrus, fusiform gyrus, and frontal cortex in response to all faces (direct and averted gaze). Left fusiform habituation in female participants was directly correlated with higher, more typical levels of the fragile X mental retardation protein and inversely correlated with autism symptoms. There was no evidence for differential habituation to direct gaze compared with averted gaze within or between groups. Impaired habituation and accentuated sensitization in response to face/eye gaze was distributed across multiple levels of neural processing. These results could help inform interventions, such as desensitization therapy, which may help patients with fragile X syndrome modulate anxiety and arousal associated with eye gaze, thereby improving social functioning.

Effects of chronic administration of fenproporex on cognitive and non-cognitive behaviors.

Fenproporex (Fen) is an amphetamine-based anorectic; amphetamine use causes a broad range of severe cognitive deficits and anxiogenic-like effects. In this study we evaluated pharmacological effects of the chronic administration of Fen on cognitive and non-cognitive behaviors. Male adult Wistar rats received intraperitoneal administration of vehicle (control group) or Fen (6.25, 12.5 or 25 mg/kg) for 14 days; the animals were then subjected to habituation and object recognition tasks in open-field apparatus, and elevated plus-maze task. The administration of Fen (12.5 and 25 mg/kg) impaired habituation during the second exposure to the habituation task. In addition, the same doses of Fen also impaired the performance in object recognition task. In elevated plus-maze task, the administration of Fen (in all doses tested) induced anxiogenic-like effects in rats. Our results suggest that chronic Fen administration alters memory and induces anxiogenic-like effects in rats.

Spared piriform cortical single-unit odor processing and odor discrimination in the Tg2576 mouse model of Alzheimer's disease.

Alzheimer's disease is a neurodegenerative disorder that is the most common cause of dementia in the elderly today. One of the earliest reported signs of Alzheimer's disease is olfactory dysfunction, which may manifest in a variety of ways. The present study sought to address this issue by investigating odor coding in the anterior piriform cortex, the primary cortical region involved in higher order olfactory function, and how it relates to performance on olfactory behavioral tasks. An olfactory habituation task was performed on cohorts of transgenic and age-matched wild-type mice at 3, 6 and 12 months of age. These animals were then anesthetized and acute, single-unit electrophysiology was performed in the anterior piriform cortex. In addition, in a separate group of animals, a longitudinal odor discrimination task was conducted from 3–12 months of age. Results showed that while odor habituation was impaired at all ages, Tg2576 performed comparably to age-matched wild-type mice on the olfactory discrimination task. The behavioral data mirrored intact anterior piriform cortex single-unit odor responses and receptive fields in Tg2576, which were comparable to wild-type at all age groups. The present results suggest that odor processing in the olfactory cortex and basic odor discrimination is especially robust in the face of amyloid β precursor protein (AβPP) over-expression and advancing amyloid β (Aβ) pathology. Odor identification deficits known to emerge early in Alzheimer's disease progression, therefore, may reflect impairments in linking the odor percept to associated labels in cortical regions upstream of the primary olfactory pathway, rather than in the basic odor processing itself.

Post-training scopolamine treatment induced maladaptive behavior in open field habituation task in rats.

The effects of scopolamine on memory consolidation are controversial and depend on several factors (i.e. site of administration, time of administration and testing, dose, cognitive task, experimental protocol, specie, strain, etc.). Generally, the range dose of systemic administered scopolamine, used in memory consolidation studies, has varied from 0.05 to 50 mg/kg. However, according to the literature, the most frequently used doses of scopolamine efficient on memory consolidation, are 1 and 30 mg/kg, low and high doses, respectively. In open field habituation studies only lower doses of scopolamine were used to test memory consolidation. Therefore, in the present study we compared the effects of low (1 mg/kg) and high (30 mg/kg) scopolamine dose, on the open field habituation task, in male Wistar rats. Scopolamine was administered immediately after the acquisition task and animals were retested 48 h later on. On the retested day, the ambulation and rearing in the open field decreased in the same manner in all tested groups. In saline- and 1 mg/kg scopolamine-treated animals, the time spent in grooming significantly decreased in the habituation task, while the same parameter significantly increased in animals treated with 30 mg/kg of scopolamine. The defecation rate significantly decreased (control group), maintained (1 mg/kg of scopolamine treated animals) or significantly increased (30 mg/kg of scopolamine treated group) on retention test. In conclusion, the present data suggest that post-training scopolamine administration does not affect locomotion neither exploration in the habituation to a novel environment, but increases defecation and grooming, two behaviours associated with fearful and stressful situations.

Contributions of COMT Val158Met to cognitive stability and flexibility in infancy

Adaptive behavior requires focusing on relevant tasks while remaining sensitive to novel information. In adult studies of cognitive control, cognitive stability involves maintaining robust cognitive representations while cognitive flexibility involves updating of representations in response to novel information. Previous adult research has shown that the Met allele of the COMT Val(158) Met gene is associated with enhanced cognitive stability whereas the Val allele is associated with enhanced cognitive flexibility. Here we propose that the stability/flexibility framework can also be applied to infant research, with stability mapping onto early indices of behavioral regulation and flexibility mapping onto indices of behavioral reactivity. From this perspective, the present study examined whether COMT genotype was related to 7-month-old infants' reactivity to novel stimuli and behavioral regulation. Cognitive stability and flexibility were assessed using (1) a motor approach task, (2) a habituation task, and (3) a parental-report measure of temperament. Val carriers were faster to reach for novel toys during the motor approach task and received higher scores on the temperament measure of approach to novelty. Met carriers showed enhanced dishabituation to the novel stimulus during the habituation task and received higher scores on the temperament measures of sustained attention and behavioral regulation. Overall, these results are consistent with adult research suggesting that the Met and Val alleles are associated with increased cognitive stability and flexibility, respectively, and thus suggest that COMT genotype may similarly affect cognitive function in infancy.

How a hat may affect 3-month-olds' recognition of a face: an eye-tracking study.

Recent studies have shown that infants’ face recognition rests on a robust face representation that is resilient to a variety of facial transformations such as rotations in depth, motion, occlusion or deprivation of inner/outer features. Here, we investigated whether 3-month-old infants’ ability to represent the invariant aspects of a face is affected by the presence of an external add-on element, i.e. a hat. Using a visual habituation task, three experiments were carried out in which face recognition was investigated by manipulating the presence/absence of a hat during face encoding (i.e. habituation phase) and face recognition (i.e. test phase). An eye-tracker system was used to record the time infants spent looking at face-relevant information compared to the hat. The results showed that infants’ face recognition was not affected by the presence of the external element when the type of the hat did not vary between the habituation and test phases, and when both the novel and the familiar face wore the same hat during the test phase (Experiment 1). Infants’ ability to recognize the invariant aspects of a face was preserved also when the hat was absent in the habituation phase and the same hat was shown only during the test phase (Experiment 2). Conversely, when the novel face identity competed with a novel hat, the hat triggered the infants’ attention, interfering with the recognition process and preventing the infants’ preference for the novel face during the test phase (Experiment 3). Findings from the current study shed light on how faces and objects are processed when they are simultaneously presented in the same visual scene, contributing to an understanding of how infants respond to the multiple and composite information available in their surrounding environment.