Both cute and threatening images drive narrowing of attention in men and women.

Appraisal theories of emotion sustain that stimuli containing high biological relevance preferentially capture our attention, regardless of their valence. In this work, we study the priming effect of both cute and threatening pictures on global/local visual processing. Seventy-eight males and 168 females in different menstrual cycle phases performed the global/local Navon letter task immediately after observing cute (infants and baby animals), threatening (animals in aggressive poses) or neutral pictures. Hierarchical stimuli were made up of global and local letters that could be either congruent (e.g. global H, localH) or incongruent (e.g. global H, localS). While we observed no interaction between affective primes and sex/menstrual cycle phase, each of these variables did have an independent effect on the global/local task. Thus, letter identification was significantly slower in the global task (only) after cute vs. neutral primes. Relevantly, the local-minus-global RT index revealed an attentional narrowing after both cute and threatening primes (vs. neutral primes) in incongruent trials. As for sex effects, a facilitation of global vs. local processing was observed in both sexes. However, women registered slower RTs than men, whereas women in the luteal phase showed faster RTs than those in follicular phase in the local task. This suggests that women, mainly those in their luteal menstrual phase, tend to rely on a more analytical style of processing while attending to hierarchical stimuli. Most importantly, stimuli containing high biological significance drive narrowing of the attentional focus in global/local visual processing, especially in conditions of higher attentional demand.

ERP Source Analysis Guided by fMRI During Familiar Face Processing.

Event related potentials (ERPs) provide precise temporal information about cognitive processing, but with poor spatial resolution, while functional magnetic resonance imaging (fMRI) reliably identifies brain areas involved, but with poor temporal resolution. Here we use fMRI to guide source localization of the ERPs at different times for studying the temporal dynamics of the neural system for recognizing familiar faces. fMRI activation areas were defined in a previous experiment applying the same paradigm used for ERPs. The Bayesian model averaging (BMA) method was used to estimate the generators of the ERPs to unfamiliar, visually familiar, and personally-familiar faces constraining the model by fMRI activation results. For this, higher prior probabilities in the solution space were assigned to the fMRI-defined regions, which included face-selective areas and other areas related to "person knowledge" retrieval. Source analysis was carried out in three-time windows: early (150-210 ms), middle (300-380 ms) and late (460-580 ms). The early and middle responses were generated in fMRI-defined areas for all face categories, while these areas do not contribute to the late response. Different areas contributed to the generation of the early and middle ERPs elicited by unfamiliar faces: fusiform (Fus), inferior occipital, superior temporal sulcus and the posterior cingulate (PC) cortices. For familiar faces, the contributing areas were Fus, PC and anterior temporal areas for visually familiar faces, with the addition of the medial orbitofrontal areas and other frontal structures for personally-significant faces. For both unfamiliar and familiar faces, more extended and reliable involvement of contributing areas were obtained for the middle compare with early time window. Our fMRI guide ERP source analysis suggested the recruitment of person-knowledge processing areas as early as 150-210 ms after stimulus onset during recognition of personally-familiar faces. We concluded that fMRI-constrained BMA source analysis provide information regarding the temporal-dynamics in the neural system for cognitive processsing.

Event-related potentials elicited by face identity processing in elderly adults with cognitive impairment.

UNLABELLED: BackGROUND/STUDY CONTEXT: Patients with mild Alzheimer's 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.

Progressive attenuation of visual global precedence across healthy aging and Alzheimer's disease.

In the perception of Navon hierarchical stimuli (e.g., large letters made up of small letters), young adults identify large letters faster than small ones (known as 'global advantage') and identify more slowly small letters when they form a different (or incongruent) large letter (known as 'unidirectional global interference'). Since some global/local perceptual alterations might be occurring with aging, we investigated whether these effects vary across healthy aging and Alzheimer's disease (AD). Here, the Navon letter task was administered to 26 healthy elderly (HE), 21 adults with mild cognitive impairment (MCI), and 26 adults with AD. The same task was administered 1 year later, and different neuropsychological variables were incorporated into the analyses. The cross-sectional study revealed no global advantage but did reveal both global and local interferences in all groups when response times were analyzed. Regarding discrimination sensitivity, HE showed unidirectional global interference, while AD displayed better discrimination of local than global letters in the incongruent condition, which denotes less interference by global distractors than by local ones. The longitudinal study revealed that 1 year later the participants with MCI showed a slowdown in inhibiting local distractors in the global task, revealing a certain bias toward focus in their attention on small stimuli. The elders with AD reflected a generalized slowing of their responses with a clear bias toward local analysis of stimuli, also suggested by their better discrimination in the incongruent local task at the second moment of assessment. Furthermore, all response timing measures in the Navon task were correlated with several neuropsychological indexes of highly sensitive neuropsychological tests, suggesting that performance in this task may also have a potential diagnostic value for differentiating typical from atypical cognitive aging. All these results support the need for a multidomain approach to define neuropsychological markers of progression toward AD, including visual perceptual organization evaluated via measures of performance quality.

Forest Before Trees: Letter Stimulus and Sex Modulate Global Precedence in Visual Perception.

The global precedence effect (GPE), originally referring to processing hierarchical visual stimuli composed of letters, is characterised by both global advantage and global interference. We present herein a study of how this effect is modulated by the variables letter and sex. The Navon task, using the letters "H" and "S," was administered to 78 males and 168 females (69 follicular women, 52 luteal women, and 47 hormonal contraceptive users). No interaction occurred between the letter and sex variables, but significant main effects arose from each of these. Reaction times (RTs) revealed that the letter "H" was identified more rapidly in the congruent condition both in the global and the local task, and the letter "S" in the incongruent condition for the local task. Also, although RTs showed a GPE in both males and females, males displayed shorter reaction times in both global and local tasks. Furthermore, luteal women showed higher d' index (discrimination sensitivity) in the congruent condition for the local task than both follicular women and hormonal contraceptive users, as well as longer exploration time of the irrelevant level during the global task than males. We conclude that, according to the linear periodicity law, the GPE is enhanced for compound letters with straight vs. curved strokes, whereas it is stronger in males than in females. Relevantly, luteal phase of the menstrual cycle seems to tilt women to rely on finer grained information, thus exhibiting an analytical processing style in global/local visual processing.

Different and common brain signals of altered neurocognitive mechanisms for unfamiliar face processing in acquired and developmental prosopagnosia.

Neuropsychological studies have shown that prosopagnosic individuals perceive face structure in an atypical way. This might preclude the formation of appropriate face representations and, consequently, hamper effective recognition. The present ERP study, in combination with Bayesian source reconstruction, investigates how information related to both external (E) and internal (I) features was processed by E.C. and I.P., suffering from acquired and developmental prosopagnosia, respectively. They carried out a face-feature matching task with new faces. E.C. showed poor performance and remarkable lack of early face-sensitive P1, N170 and P2 responses on right (damaged) posterior cortex. Although she presented the expected mismatch effect to target faces in the E-I sequence, it was of shorter duration than in Controls, and involved left parietal, right frontocentral and dorsofrontal regions, suggestive of reduced neural circuitry to process face configurations. In turn, I.P. performed efficiently but with a remarkable bias to give "match" responses. His face-sensitive potentials P1-N170 were comparable to those from Controls, however, he showed no subsequent P2 response and a mismatch effect only in the I-E sequence, reflecting activation confined to those regions that sustain typically the initial stages of face processing. Relevantly, neither of the prosopagnosics exhibited conspicuous P3 responses to features acting as primes, indicating that diagnostic information for constructing face representations could not be sufficiently attended nor deeply encoded. Our findings suggest a different locus for altered neurocognitive mechanisms in the face network in participants with different types of prosopagnosia, but common indicators of a deficient allocation of attentional resources for further recognition.

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.

Brain potentials and integration of external and internal features into face representations.

In this ERP study we analyzed how different orders of presentation of external and internal features influence the integration of facial components into face gestalts. Participants carried out a face-feature matching task in which, in each trial, external (E) and internal (I) facial features were presented separately and in sequence, followed by a complete unfamiliar face (matching or mismatching). For the E-I group of participants the order of presentation was external features, internal features and then the complete face. The I-E group viewed the internal features first. Mismatch effects in complete faces were more conspicuous and lasted from about 300 to 600 ms with the order E-I, while those with the order I-E were scarcely observable, and significant only from 450 to 470 ms. The external features tended to elicit a larger P150, while the N170 was preferentially associated with the internal ones. A P360, probably indicating stimulus relevance, was present in both groups for external features, while it was associated with internal features only in the I-E group. These results suggest that in the E-I order the binding of facial features into a single face representation occurs according to a stepwise process which facilitates the integration. In turn, in the I-E order the processing related to the two sets of features appears more dissociated and is of a more componential nature. Moreover, we propose that the external features may be especially relevant for object categorization, while internal features would be more closely related to subsequent configural mechanisms.

Source Reconstruction of Brain Potentials Using Bayesian Model Averaging to Analyze Face Intra-Domain vs. Face-Occupation Cross-Domain Processing.

We investigated the neural correlates of the access to and retrieval of face structure information in contrast to those concerning the access to and retrieval of person-related verbal information, triggered by faces. We experimentally induced stimulus familiarity via a systematic learning procedure including faces with and without associated verbal information. Then, we recorded event-related potentials (ERPs) in both intra-domain (face-feature) and cross-domain (face-occupation) matching tasks while N400-like responses were elicited by incorrect eyes-eyebrows completions and occupations, respectively. A novel Bayesian source reconstruction approach plus conjunction analysis of group effects revealed that in both cases the generated N170s were of similar amplitude but had different neural origin. Thus, whereas the N170 of faces was associated predominantly to right fusiform and occipital regions (the so-called "Fusiform Face Area", "FFA" and "Occipital Face Area", "OFA", respectively), the N170 of occupations was associated to a bilateral very posterior activity, suggestive of basic perceptual processes. Importantly, the right-sided perceptual P200 and the face-related N250 were evoked exclusively in the intra-domain task, with sources in OFA and extensively in the fusiform region, respectively. Regarding later latencies, the intra-domain N400 seemed to be generated in right posterior brain regions encompassing mainly OFA and, to some extent, the FFA, likely reflecting neural operations triggered by structural incongruities. In turn, the cross-domain N400 was related to more anterior left-sided fusiform and temporal inferior sources, paralleling those described previously for the classic verbal N400. These results support the existence of differentiated neural streams for face structure and person-related verbal processing triggered by faces, which can be activated differentially according to specific task demands.

Brain Signals of Face Processing as Revealed by Event-Related Potentials.

We analyze the functional significance of different event-related potentials (ERPs) as electrophysiological indices of face perception and face recognition, according to cognitive and neurofunctional models of face processing. Initially, the processing of faces seems to be supported by early extrastriate occipital cortices and revealed by modulations of the occipital P1. This early response is thought to reflect the detection of certain primary structural aspects indicating the presence grosso modo of a face within the visual field. The posterior-temporal N170 is more sensitive to the detection of faces as complex-structured stimuli and, therefore, to the presence of its distinctive organizational characteristics prior to within-category identification. In turn, the relatively late and probably more rostrally generated N250r and N400-like responses might respectively indicate processes of access and retrieval of face-related information, which is stored in long-term memory (LTM). New methods of analysis of electrophysiological and neuroanatomical data, namely, dynamic causal modeling, single-trial and time-frequency analyses, are highly recommended to advance in the knowledge of those brain mechanisms concerning face processing.

Long-term information and distributed neural activation are relevant for the "internal features advantage" in face processing: electrophysiological and source reconstruction evidence.

In face processing tasks, prior presentation of internal facial features, when compared with external ones, facilitates the recognition of subsequently displayed familiar faces. In a previous ERP study (Olivares & Iglesias, 2010) we found a visibly larger N400-like effect when identity mismatch familiar faces were preceded by internal features, as compared to prior presentation of external ones. In the present study we contrasted the processing of familiar and unfamiliar faces in the face-feature matching task to assess whether the so-called "internal features advantage" relies mainly on the use of stored face-identity-related information or if it might operate independently from stimulus familiarity. Our participants (N = 24) achieved better performance with internal features as primes and, significantly, with familiar faces. Importantly, ERPs elicited by identity mismatch complete faces displayed a negativity around 300-600 msec which was clearly enhanced for familiar faces primed by internal features when compared with the other experimental conditions. Source reconstruction showed incremented activity elicited by familiar stimuli in both posterior (ventral occipitotemporal) and more anterior (parahippocampal (ParaHIP) and orbitofrontal) brain regions. The activity elicited by unfamiliar stimuli was, in general, located in more posterior regions. Our findings suggest that the activation of multiple neural codes is required for optimal individuation in face-feature matching and that a cortical network related to long-term information for face-identity processing seems to support the internal feature effect.

Cognitive decline effects at an early stage: evidence from N170 and VPP.

The perceptual processing of faces was studied using event-related potentials (ERPs) in 12 elderly patients with cognitive impairment, 15 elderly adults and 16 young adults in order to explore the sensitivity of N170/VPP to the cognitive decline associated to Alzheimer's disease. Famous and unknown faces were presented in a familiarity categorization task. Eight patients and 11 elderly adults repeated this task to obtain longitudinal data. Topographical effects were analyzed using PCA. The posterior N170 showed reduced amplitude in patients with cognitive impairment and elderly adults, compared to young adults, which could indicate perceptual impairment in configural face-encoding processing. The anterior VPP showed enhanced amplitude in patients with cognitive impairment, compared to young and elderly adults, which might relate to the prefrontal dysfunction associated to mild dementia. These preliminary findings suggest that N170/VPP could be modulated by the decline related to pathological cognitive aging.

Brain potential correlates of the "internal features advantage" in face recognition.

Whereas some behavioral studies have shown that internal features are crucial for efficient face recognition in healthy adults, compared to external features, the brain mechanisms underlying this "internal features advantage" are still unknown. In the present study, the differential relevance of both subsets of facial features is addressed analyzing N400-like potentials elicited in a face-feature matching task, where external or internal features and complete face targets were displayed consecutively in each trial. Experiment 1 revealed a larger and longer-lasting N400-like effect with the prior presentation of internal features, which suggests more efficient processing of long-term face-related information. An analysis of neural sources in Experiment 2 revealed greater activation of frontal and left temporal brain areas in the processing of mismatching targets when preceded by internal features. Thus, brain electrical correlates of the "internal features advantage" could be verified around 300-400ms post-stimulus and supported by a face-identity related neural network.

Potenciales evocados como marcadores neurofisiológicos de la percepción y el reconocimiento de caras / Event-related potentials as neurophysiological markers of face perception and face recognition

La percepción y el reconocimiento de caras como funciones cerebrales complejas de gran relevancia psicobiológica son objeto de estudio por parte de la comunidad neurocientífica desde hace varias décadas. En este artículo se revisan los datos existentes sobre potenciales evocados y procesamiento de caras y se discute la significación funcional de cada una de las respuestas psicofisiológicas analizadas en relación con las diferentes etapas o módulos descritos en los modelos cognitivos y neurales sobre el procesamiento de rostros familiares y desconocidos. El procesamiento inicial de las caras está relacionado con respuestas electrofisiológicas muy tempranas como la onda occipital P120, asociada a la detección de aspectos estructurales primarios sugerentes, grosso modo, de la presencia de una cara en nuestro campo visual. La onda temporal posterior N170 es más sensible a la configuración facial (vs. otros objetos) y a la presencia de rasgos faciales distintivos antes de que se produzca la individualización intra-categorial (reconocimiento visual de la identidad), mientras que las respuestas de latencia más tardía como la temporal anterior N250r y la topográficamente más distribuida N400 son las que reflejan, respectivamente, los procesos de acceso y recuperación de información relativa a las caras conocidas en la memoria a largo plazo.

The perception and recognition of faces are complex brain functions of great psychobiological relevance and have been studied by the neuroscientific community for decades. This paper reviews existing data on event-related potentials and facial processing, therefore, the functional significance of each psychophysiological response, in relation with the different stages or modules described in cognitive and neural models regarding the processing of familiar and unknown faces are discussed. The initial processing of faces is related to early electrophysiological responses as occipital P120 wave, associated with the detection of primary structural features suggestive of, basically, the presence of a face in our visual field. The posterior temporal N170 wave is more sensitive to facial configuration (vs. other objects) and to the presence of specific facial features before the intra-categorical identification takes place (visual recognition of identity), while the later latency responses as the anterior temporal N250r and the more topographically distributed N400 are those that reflect, respectively, the access and retrieval of information on familiar faces in long-term 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 (intradomain verbal processing). Results revealed that mismatching stimuli in the four conditions elicited a mismatch negativity analogous to N400 but with different timing and topographical 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.