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. 2026 May 13;123(20):e2533498123. doi: 10.1073/pnas.2533498123

Fig. 2.

Five-panel figure with histograms A, D, E, psychometric curves B, and scatter plots C, showing data from monkeys M, D, and F.

Microstimulation in VPS induces ipsiversive bias in vestibular heading judgment. (A) Clustering of vestibular (Left) and visual (Right) heading signals in VPS assessed by Pearson correlation coefficient of tuning curves between neighboring sites apart by 100 μm (Top) and 200 μm (Bottom). (B) Examples of a microstimulation experiment, conducted first by a three consecutive sites mapping of tuning functions under fixation-only condition (Left), and then by stimulation during the heading discrimination task (Right). Dashed curves are stimulated trials. Solid curves are nonstimulated trials. Blue: vestibular; Red: visual. (C) Comparison of PSE between microstimulated (vertical axis) and control trials (horizontal axis) for all three monkeys (Left), and individuals (Right three panels). Filled dots are cases with significant difference (P < 0.05, logistic test). Open dots are cases with unchanged PSE (P > 0.05, logistic test). (D) Distribution of PSE shift induced by microstimulation for all three animals (Left) and individual animals (Right three). Positive value means the biased direction is consistent with the preferred heading of the stimulated site, and vice versa for the negative values. Filled and open bars are cases with significant (P < 0.05, logistic test) and insignificant difference (P > 0.05, logistic test), respectively. (E) (Top) similar in D, but positive value means the biased direction consistent with the hemisphere of the stimulated site (ipsilateral), and vice versa for the negative value (contralateral). Horizontal and vertical patch indicates data with significant PSE shift from Left and Right hemisphere, respectively. (Bottom) Data in the Top Left panel were separated into three groups according to the relationship between the stimulated neurons’ heading preference and hemisphere: i) ipsiversive heading preference (Left); ii) orthogonal (fore/aft) heading preference (Middle); iii) contraversive heading preference (Right). The gray semicircles represent hemispheres and the superimposed arrows represent heading preference of the stimulated neurons. Specifically, neurons with heading preference within ±60° straight to the left or to the right are defined as ← and →, respectively. Neurons with heading preference within ±30° around straight forward or backward are defined as ↑ and ↓, respectively.