Utilizing Non-invasive Neuromodulation To Explore The Visual Selective Mechanism Of Human Ventral Visual Pathway

The ventral visual cortex is an important visual information processing pathway in the visual system,and is mainly responsible for the perception of the shape of objects.It starts in the primary visual cortex(V1)and ends in the inferior temporal(IT).Previous studies have used external recording methods,such as functional magnetic resonance imaging(f MRI)and electroencephalography(EEG),to objectively explore this pathway,but they have not been able to provide the causal relationship of the mechanism of this pathway.Therefore,in the current study,non-invasive brain intervention methods such as transcranial magnetic stimulation(TMS)and transcranial direct current stimulation(t DCS),were applied to the V1 and IT to study the neural mechanism of the ventral visual pathway.The primary visual cortex is mainly responsible for detecting simple features such as the orientation of objects.In the intervention study on the V1 area,we chose the grating recognition task paradigm to explore the effect of 1Hz low-frequency r TMS on the left hemisphere V1 area on the orientation selectivity of objects.Through the TMS-EEG joint technology,it was found that obvious P1,N1,and P3 components were induced in the pre-and post-test tasks.After statistical analysis of the peak value and latency of these three components,it is found that 1Hz r TMS can suppress the increase of the peak value of P1 in the left hemisphere after acting on the left side V1,but also suppress the decrease of the peak value of P3 in the left hemisphere.Through correlation analysis,it is concluded that the N100 and P160 components induced during the TMS stimulation process can modulate the EEG components and behavioral performance induced in the grating stimulation task.The main manifestation is that the increase of the P160 component can reduce the grating detection task.The increase in the N100 component suppresses the peak value of P1 in the V1 area on the left.This result fully proves that1 Hz r TMS can have an inhibitory effect on the orientation selectivity of the V1 region,and the P1 component plays an important role in maintaining the orientation selectivity of the V1 region.The main function of the inferior temporal cortex is responsible for more complex object recognition tasks,which is closely related to object recognition processing.We use t DCS stimulation technology to stimulate the IT area,and explore the influence of cathode and anode stimulation on the identity of objects through two more classic longdistance apparent motion paradigms and letter topology RSVP paradigm.It is found that in the long-distance apparent motion experiment,when the anode acts on the IT area,the subjects tend to choose to flicker,while the cathode acting on the IT area can increase the choice of apparent motion.In the letter topology RSVP experiment,when an anode is used to act on the IT area,the object identity of non-topological letters will be significantly destroyed,and the object identity of topological objects will remain relatively stable.Through the results of the two experimental tasks,we can find that t DCS can significantly interfere with the IT area.When the anode acts on the IT area,it can reduce the perception of object identity,while the cathode acts on the IT area to enhance the identity of the object perception.