In the human brain, there are 2 major parallel pathways: the parvocellular (P) and magnocellular (M) pathways. The former has excellent spatial resolution with color selectivity, whereas the latter exhibits excellent temporal resolution, with high contrast sensitivity. Visual stimuli need to be designed in order to answer specific clinical and/or research questions about these pathways. We examined the neural mechanisms of face perception using event-related potentials (ERPs). Face stimuli with different spatial frequencies were used to investigate the manner in which the low-spatial-frequency (LSF) and high-spatial-frequency (HSF) components of the face contribute to the identification and recognition of faces and facial expressions. The P100 component in the occipital area (Oz), the N170 in the posterior temporal region (T5/T6), and late components peaking at 270-390 ms (T5/T6) were analyzed. LSF enhanced P100, whereas N170 was augmented by HSF, irrespective of facial expressions. This suggests that LSF is important for the global processing of facial expressions, whereas HSF handles featural processing. There were significant differences in amplitude between positive and negative LSF facial expressions in the early time windows of 270-310 ms. Subsequently, the amplitudes among negative HSF facial expressions differed significantly in the later time windows of 330-390 ms. Discrimination between positive and negative facial expressions precedes discrimination among the different negative expressions in a sequential manner, based on parallel visual channels. Interestingly, patients with schizophrenia showed decreased spatial frequency sensitivities for face processing. Thus, our spatially filtered face images are useful for exploring face perception and recognition. Even when presented for a subthreshold (subliminal) duration, faces were processed differently to images of other objects at an early stage of visual processing. Pl (approximately 120 ms) and N1 (approximately 160 ms) components at Oz were sensitive to unrecognizable faces in a masking paradigm. P1 performs rapid holistic detection of the face and N1 detects the facial features.
|Number of pages||10|
|Journal||Brain and Nerve|
|Publication status||Published - Jul 1 2012|
All Science Journal Classification (ASJC) codes
- Clinical Neurology