Using transcranial direct current stimulation (tDCS) to selectively modulate the face inversion effect and N170...

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Perceptual learning, particularly the face inversion effect, is crucial for recognizing familiar faces.
• The N170 event-related potential component is sensitive to face perception and is modulated by learning.
• Combining transcranial direct current stimulation (tDCS) with electroencephalography (EEG) offers a powerful approach to investigate neural mechanisms of perception.

Purpose of the Study:

• To investigate how anodal tDCS applied to the Fp3 scalp area modulates perceptual learning, specifically the face inversion effect.
• To examine the relationship between behavioural measures of the face inversion effect and the N170 component (latency and amplitude) under tDCS.
• To elucidate the neural mechanisms underlying tDCS-induced changes in face perception.

Main Methods:

• A large study (n=72) employed combined tDCS-EEG.
• Participants performed an old/new recognition task with upright, inverted, normal, and Thatcherized faces.
• Anodal tDCS was delivered to the Fp3 area with the reference electrode at Fp2, compared against a sham condition.

Main Results:

• Anodal tDCS at Fp3 increased the behavioural face inversion effect for normal faces compared to sham.
• This behavioural change covaried with modulation of the N170 component.
• A dissociation was observed: tDCS reduced N170 latency and amplitude, but behavioural modulation tracked N170 amplitude, not latency.

Conclusions:

• tDCS can modulate perceptual learning of faces, specifically impacting the behavioural face inversion effect.
• The N170 amplitude is a key neural correlate of tDCS-induced behavioural changes in face perception.
• A dissociation exists between N170 amplitude and latency in response to tDCS, offering nuanced insights into perceptual learning mechanisms.