Zona incerta distributes a broad movement signal that modulates behavior
- Department of Neuroscience, University of Connecticut School of Medicine, United States
Figures
Figure 1
Zona incerta unit activity measured with electrophysiology in head-fixed mice on a spherical treadmill reveals two groups of neurons based on their activation during movement.
(A) Schematic of the head-fixed spherical treadmill setup. The frontal air tubes deliver air-puffs to the whiskers, and the posterior air tubes deliver air-puffs to the lower back. (B) Dark-field sagittal section aligned with the Allen Brain Atlas showing a marking lesion to reference to point above the zona incerta below where recordings were obtained. (C) PSTH of unit firing (Hz) and movement (speed) traces for units classified using PCA as Class1 (upper panel) and Class2 (middle panel). Class1 units activate during movement and can be further subclassified into Class1a (blue) and Class2b (red) based on baseline firing rate. The lower panel shows the speed of the mice on the spherical treadmill (in the forward direction) for all units. Time zero corresponds to the peak of detected spontaneous movements. The left panels show all detected movement peaks, and the right panels show those peaks devoid of other peaks >4 s prior, which selects for movement onsets. (D) Population measures of unit firing rate (left), linear fit (correlation) between firing rate and movement (middle), and cross-correlation between firing rate and movement (right) for the different groups.
Figure 2
Response of zona incerta units to sensory stimuli applied to head-fixed mice on the spherical treadmill.
(A) PSTH of unit firing evoked by air-puffs to the whiskers (left panels) or lower back (right panels), and auditory stimuli consisting of a tone (8 kHz) or white noise (middle panels). Air-puffs are delivered contralateral (top panels) or ipsilateral (bottom panels) to the recording site. The black traces correspond to whisker-sensitive units (n = 33). The red traces correspond to whisker non-sensitive units (n = 137). (B) The whisker-sensitive cells in A are separated according to their class as per Figure 1. Class1 units are sensitive to movement on the treadmill (n = 15), while Class2 units are not (n = 18). Thus, whisker-sensitive neurons fall under both classes of neurons. The right panels show the PSTH of unit firing and movement for the units on the left panels. (C) Population measures of evoked firing for the units and stimuli in A. (D) Population measures of evoked firing for the units and whisker stimuli in B. (E) Population measures of firing rate per class for the whisker-sensitive units.
Figure 3
Calcium imaging fiber photometry reveals that GABAergic zona incerta neurons activate during spontaneous exploratory movement.
(A) Parasagittal sections showing the optical fiber tract reaching zona incerta and GCaMP7f fluorescence expressed in GABAergic neurons around the fiber ending for two animals. The sections were aligned with the Allen Brain Atlas. (B) Cross-correlation between movement and zona incerta F/Fo for the overall (black traces), rotational (red), and translational (blue) components (upper panel). Per session (dots) and mean ± standard error of the mean (SEM) (rectangle) linear fit (correlation, r) between overall movement and zona incerta F/Fo, including the rotational and translational components (lower panel). The lighter dots show the linear fits after scrambling one of variables (lower panel, shuffled). (C) F/Fo calcium imaging time extracted around detected spontaneous movements. Time zero represents the peak of the movement. The upper traces show F/Fo mean ± SEM of all movement peaks (black), those that had no detected peaks 3 s prior (red), and peaks taken at a fixed interval >5 s (cyan). The lower traces show the corresponding movement speed for the selected peaks.
Figure 4
GABAergic zona incerta neurons do not code the direction of spontaneous exploratory turning movements.
(A) F/Fo calcium imaging, overall movement, rotational movement, and angle of turning direction for detected movements classified by the turning direction (ipsiversive and contraversive; red and cyan) versus the side of the recording (implanted optical fiber). At time zero, the animals spontaneously turn their head in the indicated direction. The columns show all turns (left), those that included no turn peaks 3 s prior (middle), and peaks selected at a fixed interval >5 s (right). Note that the speed of the movements was similar in both directions. (B) Population measures (area of traces 3 s around the detected peaks) of F/Fo and movement (overall, rotational, and translational) for the different classified peaks. None of the measures were different between ipsiversive and contraversive movements.
Figure 5
GABAergic zona incerta neurons discharge to auditory tones in association with movement.
(A) Example F/Fo calcium imaging and movement traces (mean ± standard error of the mean [SEM]) evoked from zona incerta neurons by auditory tones (1 s) of different saliency. The tones vary in frequency (kHz) and SPL (dB). (B) Area of F/Fo and movement components measured during a time window (0–2 s) after tone onset. (C) F/Fo responses of zona incerta GABAergic neurons evoked in head-fixed lightly restrained mice by auditory tones (1 s), while noise (1 s), and air-puffs (20 ms) aimed at the contralateral whiskers as mice transition between waking (head fixed), isoflurane anesthesia and recovery from anesthesia. (D) Population measurements of area (0–2 s) and peak amplitude from pre-stimulus baseline for the conditions in C.
Figure 6
GABAergic zona incerta activation in the context of signaled active avoidance.
(A) Arrangement of the shuttle box used during signaled avoidance tasks. (B) Behavioral performance during the four different avoidance procedures showing the percentage of active avoids (black circles), avoidance latency (orange triangles), and intertrial crossings (ITCs) (cyan bars). (C) F/Fo and overall movement traces from CS onset for AA1, AA2, and AA3 (CS1 and CS2) procedures per trials classified as avoids (left) or escapes (right) of CS-evoked orienting response measured by tracking overall head speed. (D) Same as C from response occurrence. (E) Population measures of F/Fo and speed for avoids and escapes during AA1, AA2, and AA3 (CS1). Asterisks denote p < 0.05 versus Avoids.
Figure 7
GABAergic zona incerta neurons track the avoidance and escape movement.
(A) F/Fo and overall movement traces from CS onset (left) and response occurrence (right) for avoids during the AA4 procedure, which include three CSs that signal avoidance intervals of different durations. (B) Population measures (−3 to 3 s area, mean ± standard error of the mean [SEM]) from response occurrence. Asterisks denote significant differences versus other stimuli. (C) F/Fo and overall movement traces from unconditioned stimulus (US) onset for escapes during the unsignaled US procedure, which includes the US, or each of its components delivered alone (foot-shock and white noise). (D) Population measures (0–5 s area, mean ± SEM) for the data in C. Asterisks denote significant differences versus other CSs.
Figure 8
Lesions of GABAergic zona incerta neurons disrupt movement but does not abolish signaled active avoidance learning or performance.
(A) Coronal Neurotrace (green) strained section of a Vgat-Cre mouse injected with a Cre-depedent AAV-dtA in the zona incerta to kill GABAergic neurons. The red fluorophore overlying and around zona incerta is expressed in non-Cre cells signifying a successful injection. We counted the number of cells in the zona incerta in controls and injured mice and found a significant reduction of zona incerta neurons. (B) Behavioral performance during AA1, AA2, and AA3 procedures showing the percentage of active avoids (upper), avoid latency (middle), and intertrial crossings (ITCs) (lower) for control and lesion mice. The AA3 procedure shows CS1 and CS2 trials for the same sessions. Note that active avoids during AA3-CS2 trials are errors, as the mice must passively avoid during CS2. (C) Translational and rotational movement from CS onset during AA1 and AA2 procedures for control and lesion mice. A closeup of the orienting response evoked by the CS for the rotational movement is shown in the third panel. (D) Population measures of orienting, avoidance, and escape responses from CS onset and from response occurrence for translational and rotational movement. Asterisks denote p < 0.05 versus controls.
Figure 9
Optogenetic inhibition of GABAergic zona incerta neurons during exploratory and goal-directed movements.
(A) Effects of unilateral trains (blue only) or continuous (blue or green) light on head bias (angle in degrees), and speed movement (cm/s) during exploration of an open field for No Opsin controls. Negative values represent contraversive turns versus the side of the unilateral light. (B) Same as A for Vgat-ZI-Arch mice subjected to continuous green light pulses that inhibit zona incerta neurons. (C) Population measures of peak head bias and movement speed for the groups in A and B. Asterisks denote p < 0.05 versus No Opsin mice. (D) Translational and rotational movement components (speed) for Vgat-ZI-Arch mice performing AA1. The traces are from CS onset or from avoid occurrence for trials subjected to continuous bilateral green light (green) or control trials (black) delivered randomly during the same session. The third panel is a closeup of the second panel depicting the orienting response. The light is presented during the avoidance/escape intervals. All traces in the figure are mean ± standard error of the mean (SEM).
Figure 10
Optogenetic excitation of GABAergic zona incerta neurons during exploratory and goal-directed movements.
Effects of unilateral (A) or bilateral (B) trains or continuous blue light on head bias (angle in degrees), and speed (cm/s) during exploration of an open field for Vgat-ZI-ChR2 mice. Unilateral Cont and high-frequency trains of blue light drove vigorous contraversive head movements. Bilateral stimulation did not drive vigorous head movement. During unilateral light stimulation, negative values represent contraversive turns versus the side of the unilateral light. During bilateral light stimulation, negative values represent left turns. (C) Population measures of peak head bias and speed for the groups in A and B. Asterisks denote p < 0.05 versus No Opsin mice. (D), Translational and rotational movement components (speed) for Vgat-ZI-ChR2 mice performing AA1. The traces are from CS onset or from avoid occurrence for trials subjected to continuous bilateral green light (green) or control trials (black) delivered randomly during the same session. The third panel is a closeup of the second panel depicting the orienting response. The light is presented during the avoidance/escape intervals. All traces in the figure are mean ± standard error of the mean (SEM).
Figure 11
Optogenetic excitation of GABAergic zona incerta pathways to PO, pedunculo-pontine tegmentum (PPT), and superior colliculus during exploratory movements.
Effects of unilateral (A) or bilateral (B) trains or continuous blue light on head bias (angle in degrees), and speed (cm/s) during exploration of an open field for Vgat-ZI-ChR2 → PO, Vgat-ZI-ChR2 → PPT, and Vgat-ZI-ChR2 → SC mice. During unilateral light stimulation, negative values represent contraversive turns versus the side of the unilateral light. During bilateral light stimulation, negative values represent left turns. Population measures of peak head bias (C) and speed (D) for the groups in A/B. Asterisks denote p < 0.05 versus No Opsin mice. All traces in the figure are mean ± standard error of the mean (SEM).
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Zona incerta distributes a broad movement signal that modulates behavior
eLife 12:RP89366.
https://doi.org/10.7554/eLife.89366.3
