Function and Structure of Human Left Fusiform Cortex Are Closely Associated with Perceptual Learning of Faces

SummaryTraining can lead to long-lasting improvement in our perceptual ability, which is referred to as perceptual learning. Unraveling its neural mechanisms has proved difficult. With functional and structural magnetic resonance imaging (MRI), we addressed this issue by searching for the neural correlates of perceptual learning of face views over a long time course. Human subjects were trained to perform a face view discrimination task. Their behavioral performance and MRI signals were measured before, immediately after, and 1 month after training. We found that, across individual subjects, their behavioral learning effects correlated with the stability improvement of spatial activity pattern in the left fusiform cortex immediately after and 1 month after training. We also found that the thickness of the left fusiform cortex before training could predict subjects’ behavioral learning effects. These findings, for the first time, not only suggest that, remarkably, the improved pattern stability contributes to the long-term mechanisms of perceptual learning, but also provide strong and converging evidence for the pivotal role of the left fusiform cortex in adaptive face processing

Effect of facial emotion recognition learning transfers across emotions

IntroductionPerceptual learning of facial expression is shown specific to the train expression, indicating separate encoding of the emotional contents in different expressions. However, little is known about the specificity of emotional recognition training with the visual search paradigm and the sensitivity of learning to near-threshold stimuli.MethodsIn the present study, we adopted a visual search paradigm to measure the recognition of facial expressions. In Experiment 1 (Exp1), Experiment 2 (Exp2), and Experiment 3 (Exp3), subjects were trained for 8 days to search for a target expression in an array of faces presented for 950 ms, 350 ms, and 50 ms, respectively. In Experiment 4 (Exp4), we trained subjects to search for a target of a triangle, and tested them with the task of facial expression search. Before and after the training, subjects were tested on the trained and untrained facial expressions which were presented for 950 ms, 650 ms, 350 ms, or 50 ms.ResultsThe results showed that training led to large improvements in the recognition of facial emotions only if the faces were presented long enough (Exp1: 85.89%; Exp2: 46.05%). Furthermore, the training effect could transfer to the untrained expression. However, when the faces were presented briefly (Exp3), the training effect was small (6.38%). In Exp4, the results indicated that the training effect could not transfer across categories.DiscussionOur findings revealed cross-emotion transfer for facial expression recognition training in a visual search task. In addition, learning hardly affects the recognition of near-threshold expressions

Category Selectivity of Human Visual Cortex in Perception of Rubin Face–Vase Illusion

When viewing the Rubin face–vase illusion, our conscious perception spontaneously alternates between the face and the vase; this illusion has been widely used to explore bistable perception. Previous functional magnetic resonance imaging (fMRI) studies have studied the neural mechanisms underlying bistable perception through univariate and multivariate pattern analyses; however, no studies have investigated the issue of category selectivity. Here, we used fMRI to investigate the neural mechanisms underlying the Rubin face–vase illusion by introducing univariate amplitude and multivariate pattern analyses. The results from the amplitude analysis suggested that the activity in the fusiform face area was likely related to the subjective face perception. Furthermore, the pattern analysis results showed that the early visual cortex (EVC) and the face-selective cortex could discriminate the activity patterns of the face and vase perceptions. However, further analysis of the activity patterns showed that only the face-selective cortex contains the face information. These findings indicated that although the EVC and face-selective cortex activities could discriminate the visual information, only the activity and activity pattern in the face-selective areas contained the category information of face perception in the Rubin face–vase illusion

The role of gaze direction in face viewpoint aftereffect.

a b s t r a c t Face viewpoint aftereffect is a visual illusion that, after adaptation to a face side view, the perceived view direction of the same face subsequently presented near its front view is biased in a direction opposite to that of the adapted view. Eye gaze is a unique component in face not only because its direction is relatively independent of face view direction, but also because it is a primary cue for conveying social attention. Here, we studied the contribution of gaze direction adaptation to the formation of face viewpoint aftereffect. We found that a tiny (in terms of relative area) change of gaze direction in adapting face stimuli could induce a dramatic reduction in the magnitude of face viewpoint aftereffect. However, vertical inversion of the face stimuli almost abolished the reduction. Implications of these findings about face view representation and gaze direction representation are discussed

The Sluggishness of Early-Stage Face Processing (N170) is Correlated with Negative and General Psychiatric Symptoms in Schizophrenia

Patients with schizophrenia exhibit consistent abnormalities in face-evoked N170. However, the relation between face-specific N170 abnormalities in schizophrenic patients and schizophrenia clinical characters, which probably based on common neural mechanisms, is still rarely discovered. Using event-related potentials (ERPs) recording in both schizophrenic patients and healthy controls, the amplitude and latency of N170 were recorded when participants were passively watching face and non-face (table) pictures. The results showed a face-specific N170 latency sluggishness in schizophrenic patients, i.e., the N170 latencies of schizophrenic patients were significantly longer than those of healthy controls under both upright face and inverted face conditions. Importantly, the face-related N170 latencies of the left temporo-occipital electrodes (P7 and PO7) were positively correlated with negative symptoms and general psychiatric symptoms. Besides the analysis of latencies, the N170 amplitudes became weaker in schizophrenic patients under both inverted face and inverted table conditions, with a left hemisphere dominant. More interestingly, the FIEs (the difference of N170 amplitudes between upright and inverted faces) were absent in schizophrenic patients, which suggested the abnormality of holistic face processing. These results above revealed a marked symptom-relevant neural sluggishness of face-specific processing in schizophrenic patients, supporting the demyelinating hypothesis of schizophrenia