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PubMed1991

Effects of reversible inactivation by cooling of the primate face motor cortex on the performance of a trained tongue-protrusion task and a trained biting task.

1. Intracortical microstimulation (ICMS) and surface stimulation studies of primate face motor cortex have shown an extensive representation within face motor cortex devoted to movements of the tongue and face; only a very small representation for jaw-closing movements has ever been demonstrated. These data suggest that face motor cortex plays a critical role in the generation of tongue and facial movements but is less important in the generation of jaw-closing movements. Our aim was to determine whether disruption of primate face motor cortical function would indeed interfere with the generation of tongue movements but would not interfere with the generation of jaw-closing movements. 2. The face motor cortex was reversibly inactivated with the use of cooling in two monkeys that were trained to perform both a tongue-protrusion task and a biting task. Recording of single neuronal activity in the cortex beneath the thermode confirmed the reversible inactivation of the cortex. Each task involved a series of trials in which the monkey was required to produce a preset force level for a 0.5-s force holding period; the monkey received a fruit-juice reward if it successfully completed a task trial. Cooling of the ICMS-defined face motor cortex was achieved bilaterally or, in one experiment, unilaterally by circulating coolant through thermodes placed either on intact dura overlying face motor cortex in both monkeys or directly on the exposed pia in one of the monkeys;thermode temperature was lowered to 3-5 degrees C during cooling. Electromyographic (EMG) recordings were also made from masseter, genioglossus, and digastric muscles. 3. During bilateral cooling of the thermodes on the dura overlying the face motor cortex, there was a significant reduction in the success rates for the performance of the tongue-protrusion task in comparison with control series of trials (i.e., precool and postcool) in which the thermodes were kept at 37 degrees C. Quantitative analyses of force and EMG activity showed that the principal deficit was an inability of each monkey to exert sufficient force with its tongue for a sufficient length of time onto the tongue-protrusion task transducer; this deficit was paralleled by a reduction in the level of genioglossus and digastric EMG activity. At 4 min after commencement of rewarming, task performance had returned to control, precool levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Dissociations of face and object recognition in developmental prosopagnosia.

Neuropsychological studies with patients suffering from prosopagnosia have provided the main evidence for the hypothesis that the recognition of faces and objects rely on distinct mechanisms. Yet doubts remain, and it has been argued that no case demonstrating an unequivocal dissociation between face and object recognition exists due in part to the lack of appropriate response time measurements (Gauthier et al., 1999). We tested seven developmental prosopagnosics to measure their accuracy and reaction times with multiple tests of face recognition and compared this with a larger battery of object recognition tests. For our systematic comparison, we used an old/new recognition memory paradigm involving memory tests for cars, tools, guns, horses, natural scenes, and houses in addition to two separate tests for faces. Developmental prosopagnosic subjects performed very poorly with the face memory tests as expected. Four of the seven prosopagnosics showed a very strong dissociation between the face and object tests. Systematic comparison of reaction time measurements for all tests indicates that the dissociations cannot be accounted for by differences in reaction times. Contrary to an account based on speed accuracy tradeoffs, prosopagnosics were systematically faster in nonface tests than in face tests. Thus, our findings demonstrate that face and nonface recognition can dissociate over a wide range of testing conditions. This is further support for the hypothesis that face and nonface recognition relies on separate mechanisms and that developmental prosopagnosia constitutes a disorder separate from developmental agnosia.

Adult↗
PubMed2005

Brain activation during face perception: evidence of a developmental change.

Behavioral studies suggest that children under age 10 process faces using a piecemeal strategy based on individual distinctive facial features, whereas older children use a configural strategy based on the spatial relations among the face's features. The purpose of this study was to determine whether activation of the fusiform gyrus, which is involved in face processing in adults, is greater during face processing in older children (12-14 years) than in younger children (8-10 years). Functional MRI scans were obtained while children viewed faces and houses. A developmental change was observed: Older children, but not younger children, showed significantly more activation in bilateral fusiform gyri for faces than for houses. Activation in the fusiform gyrus correlated significantly with age and with a behavioral measure of configural face processing. Regions believed to be involved in processing basic facial features were activated in both younger and older children. Some evidence was also observed for greater activation for houses versus faces for the older children than for the younger children, suggesting that processing of these two stimulus types becomes more differentiated as children age. The current results provide biological insight into changes in visual processing of faces that occur with normal development.

Adolescent↗
PubMed2006

Ventrolateral prefrontal cortex activation and attentional bias in response to angry faces in adolescents with generalized anxiety disorder.

OBJECTIVE: While adolescent anxiety disorders represent prevalent, debilitating conditions, few studies have explored their brain physiology. Using event-related functional magnetic resonance imaging (fMRI) and a behavioral measure of attention to angry faces, the authors evaluated differences in response between healthy adolescents and adolescents with generalized anxiety disorder. METHOD: In the primary trials of interest, 18 adolescents with generalized anxiety disorder and 15 comparison subjects of equivalent age/gender/IQ viewed angry/neutral face pairs during fMRI acquisition. Following the presentation of each face pair, subjects pressed a button to indicate whether a subsequent asterisk appeared on the same (congruent) or opposite (incongruent) side as the angry face. Reaction time differences between congruent and incongruent face trials provided a measure of attention bias to angry faces. RESULTS: Relative to the comparison subjects, patients with generalized anxiety disorder manifested greater right ventrolateral prefrontal cortex activation to trials containing angry faces. Patients with generalized anxiety disorder also showed greater attention bias away from angry faces. Ventrolateral prefrontal cortex activation differences remained evident when differences in attention bias were covaried. Finally, in an examination among patients of the association between degree of anxiety and brain activation, the authors found that as ventrolateral prefrontal cortex activation increased, severity of anxiety symptoms diminished. CONCLUSIONS: Adolescents with generalized anxiety disorder show greater right ventrolateral prefrontal cortex activation and attentional bias away from angry faces than healthy adolescents. Among patients, increased ventrolateral prefrontal cortex activation is associated with less severe anxiety, suggesting that this activation may serve as a compensatory response.

Adolescent↗
PubMed2004

Better the devil you know? Nonconscious processing of identity and affect of famous faces.

The nonconscious recognition of facial identity was investigated in two experiments featuring brief (17-msec) masked stimulus presentation to prevent conscious recognition. Faces were presented in simultaneous pairs of one famous face and one unfamiliar face, and participants attempted to select the famous face. Subsequently, participants rated the famous persons as "good" or "evil" (Experiment 1) or liked or disliked (Experiment 2). In Experiments 1 and 2, responses were less accurate to faces of persons rated evil/disliked than to faces of persons rated good/liked, and faces of persons rated evil/disliked were selected significantly below chance. Experiment 2 showed the effect in a within-items analysis: A famous face was selected less often by participants who disliked the person than by participants who liked the person, and the former were selected below chance accuracy. The within-items analysis rules out possible confounding factors based on variations in physical characteristics of the stimulus faces and confirms that the effects are due to participants' attitudes toward the famous persons. The results suggest that facial identity is recognized preconsciously, and that responses may be based on affect rather than familiarity.

Adult↗
PubMed1992

Caricature and face recognition.

Although caricatures are often gross distortions of faces, they frequently appear to be super-portraits capable of eliciting recognition better than veridical depictions. This may occur because faces are encoded as distinctive feature deviations from a prototype. The exaggeration of these deviations in a caricature may enhance recognition because it emphasizes the features of the face that are encoded. In two experiments, we tested the superportrait hypothesis and the encoding-by-caricature hypothesis. In the first experiment, caricatures were recognized better than faces, and true caricatures of previously seen faces were recognized better than the faces from which the caricatures had been developed. In the second experiment, faces and their caricatures were tachistoscopically presented in a sequential same/different reaction time task. Subjects were slower to distinguish the stimuli when the face preceded its caricature, indicating that caricatures are more similar to the encoded representation of a face than are stimuli in which the distinctive features are deemphasized.

Adult↗
PubMed2001

[Typicality effect on holistic processing in face recognition].

Many studies have claimed that faces are more holistically recognized than other objects. It is unclear, however, whether some faces are more holistically recognized than other faces. This study examined whether typical faces are more holistically recognized than distinctive faces. In order to measure the degree of holistic processing, I used an alignment effect, which is a kind of interference effect on the part processing by the holistic processing. The alignment effect was measured as performance difference between aligned and non-aligned presentation conditions. The size of the alignment effects reflects the degree of the holistic processing. The results showed that the typical and distinctive faces showed an equal size of the alignment effects. These results suggested that the typical faces were not more holistically recognized than the distinctive faces. The implication of this results for face recognition research was discussed.

Facies↗
PubMed2001

[Impaired recognition of faces: implicit recognition, feeling of familiarity, role of each hemisphere].

We report three observations of patients who suffered from impaired face recognition following cerebral lesions. Two had classical prosopagnosia, resulting from bilateral in one case and right unilateral occipito-temporal in the other. They could not differentiate famous face from unknown ones, and did not feel any familiarity. The third patient has a normal feeling of knowing, could distinguish between familiar and unfamiliar faces, but was unable to evoke any biographical information about the personalities. Prosopagnosic patients demonstrated, in an experimental condition of learning face-name pairs, implicit knowledge. We assume that these capacities were dependent of the activation of networks coding familiar faces in memory. Mental imagery of faces were normal in theses two cases. In addition, stimulation of mental imagery in the first patient improved implicit knowledge in forced choice tasks. These cases throws a light on the respective role of each hemisphere in face recognition. The right hemisphere is advantaged in perceptual analysis, and activates, from the perceived faces, mnestic systems which codes for previously encountered faces. It generates feeling of familiarity, probably by the way of specific systems which differs from, and completes, those allowing identification. The left hemisphere enable access to semantic-biographic knowledge in a conscious, verbal and explicit way.

Aged↗
PubMedDate not supplied

Football face-mask removal with a cordless screwdriver on helmets used for at least one season of play.

CONTEXT: The Inter-Association Task Force for the Appropriate Care of the Spine-Injured Athlete recommends leaving a football player's helmet in place and removing the face mask from the helmet "as quickly as possible and with as little movement of the head and neck as possible." Although 2 groups have studied face-mask removal from new equipment, to our knowledge no researchers have investigated equipment that has been previously used. A full season of play may have a significant effect on football equipment and its associated hardware. Countless impacts, weather, playing surfaces, sweat, and other unforeseen or unknown variables might make the face-mask removal process more difficult on equipment that has been used. OBJECTIVE: To determine the percentage of face masks that we could unscrew, with a cordless screwdriver, from football helmets used for a full season. DESIGN: Cross-sectional. SETTING: Three New England high schools. PATIENTS OR OTHER PARTICIPANTS: All football helmets used at 3 local high schools were tested (n = 222, mean games, 9.7 +/- 1.2; mean practice weeks, 13.7 +/- 1.2). INTERVENTION(S): Each helmet was secured to a board, and a cordless screwdriver was used to attempt to remove all 4 screws attaching the face mask to the helmet. MAIN OUTCOME MEASURE(S): Variables included overall success or failure, time required for face-mask removal, and success by screw location. Data were analyzed with chi2, analysis of variance, and Tamhane post hoc tests. RESULTS: Overall, 832 (94%) of 885 screws were unscrewed, and 183 (82.4%) of 222 face masks were removed. Mean removal time was 26.9 +/- 5.83 seconds. Face-mask removal success was significantly different between school 1 (24 [52.2%] of 46) and schools 2 (84 [91.3%] of 92) and 3 (75 [89.3%] of 84; F(2,219) = 24.608; P < .001). The removal success rate was significantly higher at top screws (98%) than at screws adjacent to ear holes (90%) (P < .001). CONCLUSIONS: Based on our results and previous findings that demonstrated quicker access time and reduced head movement associated with the use of the screwdriver compared with cutting tools, the former may be a good tool for face-mask removal. However, an appropriate cutting tool must be immediately available should the screwdriver fail. Helmet hardware adjacent to ear holes was more vulnerable to failure, perhaps because it is protected by less padding than the top hardware. Possible causes of the higher failure rate at school 1 are the use of hardware materials subject to rust and corrosion and differences in helmet brand; these areas warrant future research and rules consideration.

Journal Article↗
PubMed1982

Abstraction of invariant face expressions in infancy.

To determine whether infants can abstract invariant face expressions across different persons (i.e., can form face expression categories), groups of 18-, 24-, and 30-week-old infants (18 boys and 18 girls per group) were habituated by the infant control procedure to photographs of 4 different female faces all wearing an identical expression (happy or surprise). In an immediately following test phase, categorization was inferred from greater generalization of habituation (less recovery of fixation) to 2 new female faces in the familiarized expression than to the same new faces in the altered (novel) expression. To rule out the possibility that generalization at test might be due to failure to discriminate the new persons, control groups of 18 boys and 18 girls at each age saw the same test faces following repeated presentations of only 1 of the 4 habituation faces. The results indicated that not until 30 weeks could infants differentiate happy and surprise expressions on a categorical basis. At 24 weeks they could distinguish a surprise expression following habituation to happy faces, but could not do the reverse. At 18 weeks they could do neither. Overall, the performance of girls was superior to that of boys. The findings are consistent with recent evidence suggesting that the ability to extract invariant configural information relative to the human face does not emerge until about 7 months of age.

Age Factors↗
PubMed1995

Dual-task interference patterns reveal differential processing of upright and inverted faces.

The concurrent-task method was used to investigate the hemispheric locus of face encoding. In each of three experiments, 48 right-handed adults performed unimanual finger tapping while encoding whole or partial faces for subsequent recognition. Faces were upright in Experiments 1 and 2 but inverted in Experiment 3. Irrespective of stimulus orientation, face encoding disrupted left- and right-hand tapping equally. Upright faces were less accurately recognized if learned during left-hand tapping than during right-hand tapping; inverted faces showed no lateralized interference. The results support tachistoscopic findings that indicate predominantly right-hemispheric processing of upright faces and bilateral processing of inverted faces.

Adolescent↗
PubMed2001

Association of the distinct visual representations of faces and names: a PET activation study.

A PET study of seven normal individuals was carried out to investigate the neural populations involved in the retrieval of the visual representation of a face when presented with an associated name, and conversely. Face-name associations were studied by means of four experimental matching conditions, including the retrieval of previously learned (1) name-name (NN), (2) face-face (FF), (3) name-face (NF), and (4) face-name (FN) associations, as well as a resting scan with eyes closed. Before PET images acquisition, subjects were presented with 24 unknown face-name associations to encode in 12 male/female couples. During PET scanning, their task was to decide whether the presented pair was a previously learned association. The right fusiform gyrus was strongly activated in FF condition as compared to NN and Rest conditions. However, no specific activations were found for NN condition relative to FF condition. A network of three areas distributed in the left hemisphere, both active in (NF-FF) and (FN-NN) comparisons, was interpreted as the locus of the integration of visual faces and names representations. These three regions were localized in the inferior frontal gyrus (BA 45), the medial frontal gyrus (BA 6) and the supramarginal gyrus of the inferior parietal lobe (BA 40). An interactive model accounting for these results, with BA 40 seen as an amodal binding region, is proposed.

Adult↗
PubMed1992

The vertex-positive scalp potential evoked by faces and by objects.

The influence of stimulus form on the scalp-recorded "vertex positive peak" (VPP) evoked by images of faces (Jeffreys 1989a) was studied in seven subjects. In separate experiments, we recorded the responses to 2D images of: (1) many different depictions of human faces; (2) the heads of several different species; (3) many familiar non-face objects; and (4) stimuli where the configuration of objects were modified to produce an "illusory" or "non-contextual" subjective impression of a face. The results showed that every facial representation, including the "illusory" stimuli, and most of the non-face objects, evoked a VPP of corresponding form and scalp distribution. The object-evoked VPPs, however, were always smaller and usually later than those evoked by the faces. VPPs of longer latency but often comparable amplitude were also recorded for impoverished compared to well-defined facial representations; and for most non-human compared to human faces. Very consistent responses were recorded to repeated presentations of the same stimulus for the same subject, but there was considerable variation in latency as well as amplitude (but not form) of the VPP evoked under identical experimental conditions for different subjects. These response properties of the VPP, suggest that its underlying physiological generators are sensitive to basic configural properties of the visual stimulus; and also the face- and object-related information are processed in the same brain area(s), although not necessarily by the same physiological mechanisms.

Adult↗
PubMed2003

Forward masking of faces by spatially quantized random and structured masks: on the roles of wholistic configuration, local features, and spatial-frequency spectra in perceptual identification.

The forward masking of faces by spatially quantized masking images was studied. Masks were used in order to exert different types of degrading effects on the early representations in facial information processing. Three types of source images for masks were used: Same-face images (with regard to targets), different-face images, and random Gaussian noise that was spectrally similar to facial images. They were all spatially quantized over the same range of quantization values. Same-face masks had virtually no masking effect at any of the quantization values. Different-face masks had strong masking effects only with fine-scale quantization, but led to the same efficiency of recognition as in the same-face mask condition with the coarsest quantization. Moreover, compared with the noise-mask condition, coarsely quantized different-face masks led to a relatively facilitated level of recognition efficiency. The masking effect of the noise mask did not vary significantly with the coarseness of quantization. The results supported neither a local feature processing account, nor a generalized spatial-frequency processing account, but were consistent with the microgenetic configuration-processing theory of face recognition. Also, the suitability of a spatial quantization technique for image configuration processing research has been demonstrated.

Adult↗
PubMed2000

Covert face recognition in neurologically intact participants.

Prosopagnosic patients may maintain some ability to recognize familiar faces, although they remain unaware of this ability. This phenomenon--called covert face recognition--was investigated in neurologically intact participants, using priming techniques. Participants were quicker to indicate that a target-name was familiar when the preceding prime-face belonged to the same person compared with an unrelated familiar person. This was observed both when prime-faces could be recognized overtly and when they were presented too briefly to be recognized overtly (Exps. 1 and 2). Thus, covert face recognition was observed in neurologically intact participants. In Exp. 3, participants were quicker to recognize a familiar face when that person's face had been seen previously, but only when it had been recognized overtly on the first encounter. These results are interpreted within the framework of an interactive activation model of face recognition.

Cognition↗
PubMed2005

Source localization of early stages of face processing.

Recent studies using ERPs in face recognition revealed that face processing starts around 100 ms after stimulus onset, 70 ms earlier than suggested before. While the neural sources of the N 170 component have repeatedly been found to be localized in the gyrus fusiformis and the inferior occipital cortex, sources have not yet been investigated for the P100 component during face processing. Therefore, we measured the ERPs elicited by faces and control stimuli in 72 subjects in order to localize the neural sources of both the P100 and the N 170 component. We observed significantly higher P100 and N 170 amplitudes to faces compared to control stimuli. LORETA source localization revealed significantly higher brain activity in the left and right gyrus fusiformis for the N 170 component, with additional regions of increased brain activation in a parieto-temporal-occipital network. For the P100, faces activated the left and right gyrus fusiformis significantly stronger than control stimuli. This study reveals that the first step of face processing (about 100 ms after stimulus presentation) is localized in the gyrus fusiformis. The second step of face processing around 170 ms involves the gyrus fusiformis, with additional activation in a more distributed network, including the occipital cortex.

Adolescent↗
PubMed1984

Facial pattern differences in long-faced children and adults.

Vertical facial morphology has traditionally been studied by examining subjects chosen because of open bite/overbite or mandibular plane angle. The underlying skeletal and dental morphology associated with clinical facial appearance of normal and vertically dysplastic children and adults has not been well documented. The purposes of this study were to (1) describe vertical facial morphology in long-, normal-, and short-faced children and long-faced and normal adults, and (2) identify morphologic factors associated with the clinical evaluation of long-faced and normal subjects. Forty-two children, 6 to 12 years old, and forty-two young adults with varied vertical facial types were examined clinically and separated into three vertical classifications: long, normal, or short face. Lateral cephalometric radiographs were obtained in natural head position and seven angular, eighteen linear, and six ratio measurements were made. Descriptive statistics were used to characterize all groups, and intergroup differences were compared using analysis of variance for the three child groups and the t test for the two adult groups. For both long-faced children and adults, anterior total face height, mandibular plane angle, gonial angle, and mandibulopalatal plane angle were significantly greater than normal. Ramus height was not significantly different from normal in the children, but there was a tendency for long-faced adults to have short rami. Excessive dentoalveolar development was evident in long-faced children but not in adults. Factors associated with the clinical identification of vertical dysplastic subjects were identified by a principal component analysis. For each component, a variable highly correlated with that component was selected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Hemispheric specialization displayed by man but not macaques for analysis of faces.

Six macaques and 20 right-handed human subjects, given identical test material, were asked to choose which of two composites, one consisting entirely of the left half of a monkey or a human face, the other of the right half, appeared most like the normal face. Confirming observations of others, the group of human subjects selected the right-half composite of the face (i.e. the left-half composite of the photograph) 68% of the time, thereby demonstrating a highly significant (P less than 0.01) bias in favor of the left visual field (right hemisphere). No such bias was present when human subjects viewed faces of monkeys, despite the fact that according to limited measurements, the faces of both species are asymmetrical. And most important, the macaques exhibited no consistent bias with either monkey or human faces. On the other hand, the monkeys did respond emotionally to these colored facial images, but not to scenery, when first presented. Also, like man, they found inverted faces but not scenery more difficult to identify than when right side up. Thus, the monkeys responded emotionally and perceptually to these images as faces, yet, unlike the human observers, displayed no hemispheric preference in making their analysis.

Adult↗