Search

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 intradomain 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

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 eventrelated 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. [ABSTRACT FROM AUTHOR]