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. 2015 Jan 21;113(9):3291–3311. doi: 10.1152/jn.00742.2014

Fig. 1.

Fig. 1.

Celestial compass cues and neural substrates of polarization vision in the locust brain. A: when the sun (yellow) is not visible, its position may still be inferred from the intensity gradient of skylight in conjunction with the pattern of polarization. The latter is related to solar position in that the course of the solar meridian represents a line of symmetry for the pattern of electrical field vectors (black bars), which are arranged in concentric circles around the sun. The degree of polarization (bar thickness) is highest along a circle at 90° angular distance from the sun. B: frontal diagram of the brain of the desert locust. Bilateral pathways of polarization-sensitive neurons from the optic lobes converge onto a polarization-vision network in the central complex. An anterior pathway (red neuropils) connects the dorsal rim area of the lamina and medulla (DRLA and DRME) via the anterior lobe of the lobula (ALO), the anterior optic tubercle (AOTU), and the medial (MBU) and lateral (LBU) bulb to the lower division of the central body (CBL) of the central complex. A parallel pathway (yellow neuropils) originating in the ALO is connected via the AOTU and lateral accessory lobe (LAL) to the upper division of the central body (CBU). The superior medial protocerebrum (SMP) is connected to the CBU via the anterior bundles (AB). Finally, projections from the accessory medulla (AME) extend to the posterior optic tubercle (POTU) and likely target tangential neurons entering the protocerebral bridge (PB; green). CA, calyx of mushroom body; LA, lamina; ME, medulla. Together with the LAL, the MBU and LBU make up the lateral complex (LX). C: basic types of polarization-sensitive neuron of the central complex. Columnar neurons connect distinct slices of the PB to the CBU (CPU neurons) or CBL (CL neurons) of the central body and have additional arborizations in the lateral complexes. Tangential neurons invade many or all slices within the CBL (TL) or the PB (TB). A courtesy of Dr. Keram Pfeiffer, B modified from Pfeiffer and Homberg (2014), and C modified from Müller et al. (1997) and Heinze and Homberg (2007, 2008) with permission.