Jaime Iglesias

Infants' responses to adult static facial expressions☆

Visual fixation and positive-negative behaviors of 36 4- to 9-month-old infants to happy, angry, and neutral faces were investigated by means of an infant-control habituation-recovery procedure. Infants visually discriminated the facial expressions, and their behaviors tended to vary according to the affective meaning of each one.

A Study on the Emotional Processing of Visual Stimuli through Event-Related Potentials☆☆☆

The effect of emotional charge of visual stimuli on cerebral activity was investigated through ERPs. This emotional charge is explained through two dimensions: arousal (relaxing-activating) and valence (attractive-repulsive). Stimuli were 12 paintings selected through questionnaires: three activating-attractive pictures (A+ group), three activating-repulsive (A-), three relaxing (R), and three neutral (N). The ERPs were recorded from the 31 subjects at F3, Fz, F4, C3, Cz, C4, P3, Pz and P4. N200 and P300 did not show significant reactions to the emotional charge of the stimuli. N300 showed greater amplitudes in response to activating stimuli: at frontal sites for A+ and at parietal sites for A-.

Differential effects of object-based attention on evoked potentials to fearful and disgusted faces

Event-related potentials (ERPs) were used to investigate the role of attention on the processing of facial expressions of fear and disgust. Stimuli consisted of overlapping pictures of a face and a house. Participants had to monitor repetitions of faces or houses, in separate blocks of trials, so that object-based attention was manipulated while spatial attention was kept constant. Faces varied in expression and could be either fearful or neutral (in the fear condition) or disgusted or neutral (in the disgust condition). When attending to faces, participants were required to signal repetitions of the same person, with the facial expressions being completely irrelevant to the task. Different effects of selective attention and different patterns of brain activity were observed for faces with fear and disgust expressions. Results indicated that the perception of fear from faces is gated by selective attention at early latencies, whereas a sustained positivity for fearful faces compared to neutral faces emerged around 160ms at central-parietal sites, independent of selective attention. In the case of disgust, ERP differences began only around 160ms after stimulus onset, and only after 480ms was the perception of disgust modulated by attention allocation. Results are interpreted in terms of different neural mechanisms for the perception of fear and disgust and related to the functional significance of these two emotions for the survival of the organism.

Searching for face-specific long latency ERPs: a topographic study of effects associated with mismatching features

In a previous study [E. Olivares, M.A. Bobes, E. Aubert, M. Valdés-Sosa, Associative ERPs effects with memories of artificial faces, Cogn. Brain Res. 2 (1994) 39-48] we reported the presence of a negativity associated with mismatching features when subjects carried out a face-feature matching task whilst their evoked potentials were recorded. Since the stimuli used were learned faces (realistic drawings), for which the subjects possessed no semantic information or associated verbal labels, the mismatch negativity obtained was considered a face-specific N400. In this work we present a new experiment to study the topographic distribution of these mismatch effects. As in the above-mentioned study, in each trial the subjects observed previously an incomplete (without the eyes/eyebrows fragment) familiar face, which served as a structural context for the face recognition. The face was then completed by grafting either matching (learned) features or mismatching features (from another face). In line with neuropsychological studies on prosopagnosia and electrophysiological findings in humans and non-human primates, we found as one of the most relevant items of data that the most-posterior (principally, left occipital) cortices appear to be a region in which are located the possible neural generators of the negativity associated with the detection of incongruencies in the structure of familiar faces. We also reported a late positivity, distributed in more anterior regions, which follows the mismatch negativity. This complex N-P is interpreted as reflecting a dual process of retrieval and integration of information in memory.

Long-Latency ERPs and Recognition of Facial Identity

N400 brain event-related potential (ERP) is a mismatch negativity originally found in response to semantic incongruences of a linguistic nature and is used paradigmatically to investigate memory organization in various domains of information, including that of faces. In the present study, we analyzed different mismatch negativities evoked in N400-like paradigms related to recognition of newly learned faces with or without associated verbal information. ERPs were compared in the following conditions: (1) mismatching features (eyes-eyebrows) using a facial context corresponding to the faces learned without associated verbal information (pure intradomain facial processing); (2) mismatching features using a facial context corresponding to the faces learned with associated occupations and proper names (nonpure intradomain facial processing); (3) mismatching occupations using a facial context (cross-domain processing); and (4) mismatching names using an occupation context (intra-domain verbal processing). Results revealed that mismatching stimuli in the four conditions elicited a mismatch negativity analogous to N400 but with different timing and topo-graphical patterns. The onset of the mismatch negativity occurred earliest in Conditions 1 and 2, followed by Condition 4, and latest in Condition 3. The negativity had the shortest duration in Task 1 and the longest duration in Task 3. Bilateral parietal activity was confirmed in all conditions, in addition to a predominant right posterior temporal localization in Condition 1, a predominant right frontal localization in Condition 2, an occipital localization in Condition 3, and a more widely distributed (although with posterior predominance) localization in Condition 4. These results support the existence of multiple N400, and particularly of a nonlinguistic N400 related to purely visual information, which can be evoked by facial structure processing in the absence of verbal-semantic information.

MOTHER AND INFANT SMILING EXCHANGES DURING FACE-TO-FACE INTERACTION IN INFANTS WITH AND WITHOUT DOWN SYNDROME

We examined social smiling in infants with and without Down syndrome, aged from 3.2 to 13.6 months old. They were videotaped during an episode of spontaneous face-to-face interaction and a subsequent mothers still-face situation. Results indicated that infants smiled longer in the spontaneous face-to-face episode than in the still-face episode, even though this result was only significant in typically developing infants. Typically developing infants also smiled for a longer period than Downs syndrome infants during the spontaneous interaction episode. Moreover, infants smile preceded the onset of the mothers smile, but in 6.2- to 13.6-month-old typically developing infants, the probability of mothers smiling before infants increased. These findings emphasize the possible existence of differences in the development of facial expression from signs to social symbols between infants with and without Down syndrome.

Face-to-face emotion interaction studies in Down syndrome infants:

Infants with Down syndrome constitute an ideal population for analysing the development of emotional expression from the first months of life, due basically to the fact that this chromosomal alteration is identifiable from birth and results in well-known difficulties of cognitive development and in basic learning processes. Taking into account the functional aspects of facial expression during initial social interaction, in this review we present a series of studies which, although based on different theoretical approaches and different methodologies, have the common objective of analysing the emotional behaviour of young infants with and without Down syndrome during face-to-face interaction with their mothers. The main conclusions emerging from these studies are: (a) that, as in the case of typically developing infants, Down syndrome infants and their mothers present a series of coordinated and interdependent expressive interchanges; (b) that, despite the differences found between infants with and without Down syndrome in quantitative parameters of expressive behaviour, such as frequency, duration and intensity of the different emotional expressions or their point of initiation in development, what seems to be most significant is the clear functional similarity observed in the two groups of subjects during initial mother-infant interaction; and (c) that these differences may be understood by considering different psychobiological explanations as well as the known cognitive deficits.

Looking Behavior and Smiling in Down Syndrome Infants

We studied the relation between direction of gaze and smiling in 15 typically developing infants and 15 infants with Down syndrome. All of them were videotaped during face-to-face interaction with their mothers at home, and while having access to their familiar toys. Results showed that mothers in the two groups behaved in a similar way; that Down syndrome infants looked at their mothers face for longer than typically developing children; and that the relationship between looking and smiling was similar in the two cases and reflected as an increase in the time the infant looked at its mothers face and a decrease in the time the infant looked at toys. It was deduced that Down syndrome infants are capable of distinguishing the differential significance of faces and toys, so that, in the same way as typically developing infants, they direct their affective behavior fundamentally towards the social element, which leads us to consider the affiliative function implied by this expression.

Event-Related Potentials Elicited By Face Identity Processing In Elderly Adults With Cognitive Impairment

Background/Study Context: Patients with mild Alzheimers disease and mild cognitive impairment show selective loss of knowledge regarding facial identification. Methods: The authors focus on decline effects on event-related potentials (ERPs) P100, N170, N250, and N400, associated with the processing of facial identity. Different famous and unknown faces were presented in explicit and implicit familiarity tasks. Results: Patients with cognitive impairment showed modulations on P100 and N170 and greater activity in prefrontal areas in the earlier component. In healthy elderly individuals, but not in patients, famous faces modulated the long-latency ERPs N250 and N400, related to the access and retrieval of stored facial-related information, respectively. Conclusion: ERPs have potential as markers of neurodegenerative disease such as dementia. The neural systems supporting facial identification may differ in normal and cognitively impaired older adults.

Neuropsychological stydy of familial Alzheimer's disease caused by mutation E280A in the presenilin 1 gene

In Antioquia, Colombia, investigators have recently discovered the largest family with the E280A mutation in the presenilin 1 gene that causes one type of familial Alzheimers disease (FAD). The current study compares two groups within this family: those diagnosed with Alzheimers disease (AD) in its early stage (nine subjects) and relatives (carriers) who did not show any signs of dementia (nine subjects). A battery of the following neuropsychological tests was administered to subjects in both groups: the Consortium to Establish a Registry for Alzheimers Disease (CERAD), a Phonological Verbal Fluency test, the Visual “A” Cancellation Test, memory of three phrases, the Rey-Osterrieth Complex Figure, and the Trail Making Test Part A. Statistical analyses of the average test scores of each group showed that the AD group scored significantly (p < 0.01 or p < 0.05) lower on 29 of the 43 neuropsychological variables measured (67 percent). Therefore, this specific battery was useful in discriminating subjects with AD from their healthy relatives who are carriers of the disease. The AD group as a whole presented slight dementia with predominant deficits in memory, language, praxis, and attention. This profile is similar to those reported in subjects with sporadic AD in its early stage and confirms the findings found in other neuropsychological studies of subjects with FAD linked to mutations in chromosome 14.