Tag: Synaptic_neuropil_domain

adult accessory mesothoracic neuropil [FBbt_00004091]

Region of dense neuropil located at the interface between the mesothoracic neuromere and the prothoracic neuromere, ventral to the tectulum (Court et al., 2020). It mostly contains sensory afferents from the wing and notum that enter the central nervous system via the anterior dorsal mesothoracic nerve (Power, 1948; Court et al., 2020).

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adult antennal lobe [FBbt_00007401]

The adult antennal lobe is a bilaterally paired synaptic neuropil domain of the deutocerebrum lying in front of the protocerebral synaptic neuropil domains. It is divided into approximately 50 glomeruli and is clearly separated from adjacent neuropil domains by an extensive glial sheath. The two antennal lobes are connected by the antennal commissure and receive olfactory receptor neuron axons from the antennal nerve and subesophageal tract. It is also connected to the antennal lobe tracts and the broad root.

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adult anterior ventral sensory compartment [FBbt_00051419]

Adult sensory region of the subesophageal zone that develops from the larval anterior ventral sensory compartment (Kendroud et al., 2018). It receives fibers from the anterior root of the maxillary-labial nerve and fibers of the pharyngeal nerve (Kendroud et al., 2018).

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adult central sensory compartment of subesophageal zone [FBbt_00051418]

Adult sensory region of the subesophageal zone that develops from the narrow anterior (tritocerebral and gnathal) region of the larval central sensory compartment (Kendroud et al., 2018). It encompasses the antennal mechanosensory and motor center at its anterior end, containing the axon terminals of Johnston organ neurons entering via the antennal nerve (Kendroud et al., 2018). At its posterior end, it receives axonal projections of thoracic and abdominal sensory neurons, which enter the subesophageal zone via the cervical connective (Kendroud et al., 2018).

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adult crepine [FBbt_00045037]

A thin, bilaterally paired synaptic neuropil domain that wraps around the medial lobe of the mushroom body. Many neurons in this domain enter the lobes to form extensive connections with Kenyon cell fibers. The name crepine is used in French cuisine to refer to a slice of meat wrapped around some delicacy. The posterior region of the crepine corresponds to the dorsal part of the inferior dorsofrontal protocerebrum (IDFP) of Chiang et al., (2011) (Ito et al., 2014).

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adult lateral accessory lobe [FBbt_00003681]

A bilaterally paired synaptic neuropil domain of the adult brain with a roughly pyramidal shape that is located inferior-lateral to the ellipsoid body and anterior-inferior to the bulb (lateral triangle). It lies behind the antennal lobe and in front of the ventral complex. The LAL corresponds to part of the anterior superior part of the vmpr of Otsuna and Ito (2006) and to the ventral part of the inferior dorsofrontal protocerebrum (IDFP) of Chiang et al., (2011) (Ito et al., 2014).

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adult lateral horn [FBbt_00007053]

Dorsolateral horn-shaped synaptic neuropil domain of the adult protocerebrum that houses the terminals of various antennal lobe projection neurons (Ito et al., 2014). It is not separated from other neuropils by a glial sheath, but by the extent of arborization and synapsing of these antennal lobe projection neurons (Ito et al., 2014).

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adult sensory region of subesophageal zone [FBbt_00051393]

Synaptic neuropil domain of the adult subesophageal zone that houses the axon terminals of sensory neurons (Miyazaki and Ito, 2010; Kendroud et al., 2018). These can be defined based on the projection patterns of neurons entering the brain via particular roots of the maxillary-labial, pharyngeal and antennal nerves (Kendroud et al., 2018).

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antennal mechanosensory and motor center [FBbt_00003982]

Adult neuropil domain that receives the axonal projections of the Johnston organ neurons (JONs) (Ito et al., 2014). It is part of the saddle, which is found in a relatively dorsal part of the subesophageal zone (Ito et al., 2014). It develops from the anteriormost (tritocerebral) part of the larval central sensory column, which greatly increases in size as JON axons enter it via the antennal nerve during metamorphosis (Kendroud et al., 2018). Afferents of the JONs also invade the mandibular and maxillary neuromeres (Kendroud et al., 2018).

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anterior maxillary sensory center [FBbt_00040057]

Region of the adult tritocerebrum that houses the axonal terminals of sensory neurons that enter the brain via the anterior root of the maxillary-labial nerve (Miyazaki and Ito, 2010; Kendroud et al., 2018) including gustatory receptor neurons of labellum sensilla (Miyazaki and Ito, 2010). It forms part of the anterior ventral sensory compartment (Kendroud et al., 2018). Three distinct subregions can be identified: a lateral anteriormost zone (AMS1), a lateralmost zone (AMS2) and a medial zone that reaches the midline (AMS3) (Miyazaki and Ito, 2010). Carbon-dioxide-sensitive neurons from the medial taste pegs of the labellum (identified in E409-GAL4 and NP107-GAL4) terminate in the AMS1 zone (Miyazaki and Ito, 2010).

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anterior optic tubercle [FBbt_00007059]

Synaptic neuropil domain of the adult protocerebrum that receives extensive arborizations from visual projection neurons from the lobula and the medulla, projecting via the anterior optic tract. It protrudes from the anterior-most area of the ventro-lateral neuropils and is slightly detached from the ventro-lateral protocerebrum. This neuropil is absent from the larval brain, being formed during pupal development. Otsuna and Ito (2006) suggest that the optic tubercle may be divided into three regions according to the density of arborizations. The medial-most (optu1) and lateral-most (optu3) contain dense arborizations of the Lcn10 neurons, whilst the area between these regions (optu2) is essentially devoid of the lobula columnar neurons.

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anterior ventrolateral protocerebrum [FBbt_00040043]

An aglomerular, bilaterally paired synaptic neuropil domain of the adult ventrolateral protocerebrum (VLP) that protrudes from the anterior brain between the optic lobe and the antennal lobe. It is located in front of the posterior VLP and below the anterior optic tubercle and superior clamp. It receives input from neurons projecting from the optic lobe.

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antler [FBbt_00045039]

Thin, elongated, antler-shaped, bilaterally paired synaptic neuropil domain spanning from the inferior bridge to the inferior edge of the superior lateral protocerebrum. It runs through the space between the protocerebral bridge and the fan-shaped body, along the medial surface of the medial antennal lobe tract. The antler corresponds to part of the medial part of the pimpr of Otsuna and Ito (2006) and to the dorsal part of the caudalcentral protocerebrum (CCP) of Chiang et al., (2011) and to part of the posterior inferior protocerebrum (Ito et al., 2014).

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asymmetrical body [FBbt_00110172]

Round synaptic neuropil of the central complex, adjacent to the ventralmost layer (1) of the fan-shaped body and dorsal to the noduli, on either side of the midline (Wolff and Rubin, 2018). The right asymmetrical body is, on average, 4x larger (by volume) than the left and some neurons have a bias towards the right hemisphere in their innervation patterns (Pascual et al., 2004; Jenett et al., 2012; Wolff and Rubin, 2018). In a small proportion (7.6%) of wild-type flies, this structure is symmetrical, with prominent (right side-like) innervation in both hemispheres (Pascual et al., 2004). This structure was identified by the expression of the neural protein fasciclin II (FasII) (Pascual et al., 2004). Wolff and Rubin (2018) claim this is a distinct neuropil to the fan-shaped body based on the restriction of neuronal arbors to one or the other.

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bulb [FBbt_00003682]

A bilaterally paired synaptic neuropil domain located lateral to the ellipsoid body and anterior lateral to the fan-shaped body. It contains 80 microglomeruli characterized by their granular texture. It is formed primarily by the collateral arborizations of neuronal fibers that project to the ellipsoid body and by the terminals of the fibers projecting from the anterior optic tubercle and other neuropils. The bulb corresponds to the medial part of the mimpr of Otsuna and Ito, (2006) and to the lateral triangle of Chiang et al., (2011) (Ito et al., 2014).

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cantle [FBbt_00045051]

A small, bilaterally paired, triangular synaptic neuropil domain that lies at the posterior end of the saddle. It is clearly demarcated by glial boundaries. The name ‘cantle’ was taken from the seat-back part of the horse-riding saddle. The cantle corresponds to the ventroposterior part of the ventromedial protocerebrum (VMP) of Chiang et al., (2011) and to the posterior periesophageal neuropils (Ito et al., 2014).

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clamp [FBbt_00040047]

Synaptic neuropil domain lying between the fan-shaped body, the protocerebral bridge and mushroom body pedunculus, including the area above and below the pedunculus (the space occupied by the pedunculus forms a deep tunnel-like recess on its inferior lateral side). Few neurons in the clamp penetrate the pedunculus, but some enter the glomerular posterior lateral protocerebrum and posterior ventrolateral protocerebrum (PLP, PVLP), forming a characteristic cylindrical architecture around the pedunculus. Some fibers spanning the superior surface project into the superior arch commissure.

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ellipsoid body [FBbt_00003678]

A doughnut shaped synaptic neuropil domain of the central complex of the adult brain that lies just anterior to the fan-shaped body. Its hole (the ellipsoid body canal) points anteriorly and has an axon tract (the anterior bundle) running through it. It is divided into concentric layers and into 16 radial segments, 8 per hemisphere, numbered 1-8 from superior medial to inferior medial (Ito et al., 2014).

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embryonic/larval antennal lobe [FBbt_00007127]

Paired synaptic neuropil domain of the larval deutocerebrum, located ventral to the mushroom body, that is the major target of innervation for axons carried by the antennal nerve. It is also connected to the antero-basal tract (ABT). Its posterior boundary contacts the lateral accessory lobe, ventromedial cerebrum, ventrolateral protocerebrum and periesophageal neuropils. It is the larval counterpart of the adult antennal lobe, and consists of around 22 glomeruli. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval clamp [FBbt_00111204]

A synaptic neuropil domain of the larval brain located posterior to the medial lobe of the mushroom body. It is separated from the posterior inferior protocerebrum by the antenno-cerebral tract and peduncle. Its axons project mainly into the posterior transverse tract and it receives a branch of the antenno-cerebral tract. It is the larval counterpart of the adult clamp. Note - description of relative location of brain structures in this definition is based on Pereanu et al., 2010 third instar larval brain.

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embryonic/larval crepine [FBbt_00007118]

Small synaptic neuropil domain of the larval protocerebrum that is located anterior to the medial mushroom body lobe. It contains numerous fine axons which project medially and contribute to the anterior transverse tract (ATT) and the medial cervical tract (MCT). It is the larval counterpart of the adult crepine. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval fan-shaped body - primordial [FBbt_00111207]

The primordium of the adult fan-shaped body in the larval posterior inferior protocerebrum (IPp or CPM). It consists of a bilaterally symmetrical slightly curved, horizontal, bar-shaped structure of tufts of filopodia, with undifferentiated synapses, branching off axon bundles stretching from the midline region posterior and adjacent to the mushroom body medial lobe, to a plexus slightly medial to the peduncle. In the late larval brain both halves are interconnected by a plexus of commissural fibers. It is formed by fan-shaped body pioneer neurons in the embryo/early larva and grows during larval development as it is invaded by secondary neurons (Andrade et al., 2019).

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embryonic/larval lateral accessory lobe [FBbt_00007067]

One of a group of synaptic neuropil domains of the larval brain which are located ventral to the mushroom body and are grouped around the long axon tracts connecting the larval protocerebrum to the ventral nerve cord. This medially located compartment is posterior to the antennal lobe. It is the larval counterpart of the adult lateral accessory lobe. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval nodulus - primordial [FBbt_00007722]

A small primordium in the larval brain that will give rise to the adult noduli. It appears as a ventrally directed process of the lateral primordial fan-shaped body. It is demarcated from the surrounding medial clamp and crepine by different the different concentration of synapses (e.g. as assayed by Bruchpilot expression). It develops from elements of the DPMm1, DPMpm1/2 and CM4 lineages.

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embryonic/larval periesophageal neuropils [FBbt_00007129]

One of a group of synaptic neuropil domains of the larval brain which are located ventral to the mushroom body and are grouped around the long axon tracts connecting the larval protocerebrum to the ventral nerve cord. This compartment contacts the antennal lobe posteriorly and guides the medial cervical tract (MCT). It is the larval counterpart of the adult periesophageal neuropils. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval posterior inferior protocerebrum [FBbt_00007070]

A synaptic neuropil domain of the larval brain located posterior to the medial lobe of the mushroom body. It is separated from the clamp by the antenno-cerebral tract to which it is connected via a branch. Most of the posterior inferior protocerebrum (CPM domain) is displaced during pupal development. The region at the most posterior edge remains and gives rise to part of the adult posterior inferior protocerebrum. The adult central complex arises from secondary axonal tracts of several lineages that invade the CPM, forming dense layers of neuropil and displacing it. Developmental relation to adult synaptic neuropil domain is a PC from Volker Hartenstein. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval posterior lateral protocerebrum [FBbt_00007723]

A synaptic neuropil domain located ventro-postero-laterally in the larval central brain (posterior part of BPL). Anteriorly, the great commissure (BLAv1,BLD5) defines the boundary, in the coronal plane, with the ventrolateral protocerebrum (VLP). Dorsally, there is a slim border with the superior lateral protocerebrum (SLP). Medially, a virtual sagittal plane intersecting the CP1v tract and the Balp2/3 tract separates the this domain from the ventromedial cerebrum (VMCp). Laterally, a glial septum and BLP1/2 tract separates it from the lobula. The clamp is dorso-medial and laterally, the boundary is a continuation posteriorly of the clamp-VLP border i.e. the virtual plane defined by the LEFp(CP1v) and PLF(CP2/3v) fascicles to LEFa(DALv1) fascicle (Hartenstein et al., 2015). The superior lateral protocerebrum (SLP) forms a slim ventral border with the PLP, which is defined by the entry point of the trSI(BLD1-4) fascicle; in addition, a higher synaptic density (e.g. as assayed using the presynaptic marker bruchpilot) demarcates the posterior SLP from the PLP. Developmental relation to adult synaptic neuropil domain is a PC from Volker Hartenstein. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval protocerebral bridge - primordial [FBbt_00111206]

The primordium of the adult protocerebral bridge in the larval brain, formed from the DPMm1 and DPMpm1/2 and CM4 lineages. Unlike in the adult, this exists as a bilateral pair of separate domains that do not join across the midline. These domains are tubular shaped regions containing both differentiated and undifferentiated synapses, in the posterior inferior protocerebrum (IPp or CPM). Each domain curls around the dorsal side from the posterior, growing during the larval period towards the midline. Fusion of the two halves, just posterior to the PLPC (DPLp1) commissure and fan-shaped body, only occurs 48h after pupariation.

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embryonic/larval superior intermediate protocerebrum [FBbt_00007721]

A small synaptic neuropil that has the shape of a hemi-cylinder. It flanks the mushroom body vertical lobe laterally and posteriorly, where it wedges in between superior lateral protocerebrum (SLP) and superior medial protocerebrum (SMPp). Its boundary can be followed posteriorly from the SLP-prAOTU boundary (at the DALd lineage entry point), past the distal segment (internal, lateral) curve of the trSA (DPLal1-3) and continuing further posteriorly until the entry point of DPLc. It borders the lateral clamp and (briefly) crepine compartments and (very anteriorly and ventrally) the spur. It is distinguishable from these by its higher density of synapses (e.g. as assayed by Bruchpilot expression).

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embryonic/larval superior lateral protocerebrum [FBbt_00007064]

A thin layer or neuropil of the larval brain that forms during the third instar from a dorsal region of the clamp by growth of a neuropil glial sheath across it. It is the precursor to the adult superior lateral and intermediate protocerebrum and lateral horn domains. Note - description of relative location of brain structures in this definition is based on Pereanu et al., 2010 third instar larval brain.

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embryonic/larval superior medial protocerebrum [FBbt_00111203]

A synaptic neuropil domain of the larval brain that is located dorsal to the medial lobe of the mushroom body. It is the larval counterpart of the adult superior medial protocerebrum. Note - description of relative location of brain structures in this definition is based on Pereanu et al., 2010 third instar larval brain.

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embryonic/larval ventrolateral protocerebrum [FBbt_00007068]

One of a group of synaptic neuropil domains of the larval brain which are located ventral to the mushroom body and are grouped around the long axon tracts connecting the larval protocerebrum to the ventral nerve cord. This compartment contacts the antennal lobe posteriorly, and is lateral to the lateral accessory lobe and ventromedial cerebrum. It grows anteriorly during larval development. It is the larval counterpart of the adult ventrolateral protocerebrum. Developmental relation to adult synaptic neuropil domains comes from a personal communication from Volker Hartenstein. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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embryonic/larval ventromedial cerebrum [FBbt_00007063]

One of a group of synaptic neuropil domains of the larval brain which are located ventral to the mushroom body and are grouped around the long axon tracts connecting the larval protocerebrum to the ventral nerve cord. This medially located compartment contacts the antennal lobe posteriorly. The lateral cervical tract ascends through the center of this compartment. It is the larval counterpart of the adult ventromedial neuropils. Note - description of relative location of brain structures in this definition is based on Younossi-Hartenstein et al., 2003 description of the first instar larval brain and Pereanu et al., 2010 third instar larval brain.

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epaulette [FBbt_00040040]

A small, bilaterally paired synaptic neuropil domain of the ventral complex, lying below the inferior clamp and superior-lateral to the vest. The name is taken from the ornamental shoulder piece of military generals based on its shape and position relative to other sartorially named domains of the ventral complex. The epaulette corresponds to part of the inferior region of the vmpr of Otsuna and Ito (2006) and the part of the precommissural ventromedial cerebrum (Ito et al., 2014).

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fan-shaped body [FBbt_00003679]

The largest synaptic neuropil domain of the adult central complex, located posterior to the ellipsoid body and anterior to the protocerebral bridge (Hanesch et al., 1989; Wolff et al., 2015). The fan-shaped body is composed of a rough 2-dimensional grid of layers and columns (Hanesch et al., 1998; Wolff et al., 2015; Hulse et al., 2020). Eight horizontal layers, numbered bottom to top, form a fan shape and can be divided into vertical columns (sometimes called staves, slices or segments) (Ito et al., 2014; Wolff et al., 2015). An additional, much narrower, 9th layer, which lacks a columnar organization, sits dorsal to layer 8 (Wolff et al., 2015). The number of columns varies for different neuronal types (Scheffer et al., 2020). Previously thought to be 8 slices per hemisphere numbered from 1-8 medial to lateral - arranged in 4 closely associated pairs (Ito et al., 2014). Each of the two neighboring slices (1-2, 3-4, 5-6, 7-8) are associated more closely because they receive small-field columnar neurons generated by the same neuroblasts, forming four groups on each side of the midline, from lateral to medial: segment pair W, X, Y and Z (Boyan and Williams, 2011; Ito and Awasaki, 2008). Six to nine layers can be identified, depending on the staining that is used (Hanesch et al., 1989; Young and Armstrong, 2010; Kahsai and Winther, 2011, Lin et al., 2013, Wolff et al., 2015). Recent papers divide the FB into 9 layers (Wolff et al., 2015; Scheffer et al., 2020).

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flange [FBbt_00045050]

A small, bilaterally paired, triangular synaptic neuropil domain that lies above the anterior end of the saddle, on both sides of the esophagus (Ito et al., 2014). It lies at the root of the median bundle, behind the prow (Ito et al., 2014). It forms the dorsal part of the adult tritocerebrum, developing from the centromedial and dorsal domains of the larval tritocerebrum (Hartenstein et al., 2018). The flange corresponds to the dorsoposterior part of the subesophageal ganglion (SOG) of Chiang et al., (2011) and to part of the anterior periesophageal neuropils (Ito et al., 2014).

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gall surround [FBbt_00051264]

Poorly defined region surrounding the gall that houses the arbors of some central complex neurons (Wolff et al., 2015; Hulse et al., 2020). Synapses of some neurons in this region have an elongated-bar morphology and contain dense core vesicles, suggestive of neuropeptide or neuromodulator release (Hulse et al., 2020).

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gorget [FBbt_00040039]

A thin plate-like, bilaterally paired synaptic neuropil domain that protrudes medially from below the inferior clamp to the area between the great commissure and the central body. Its medial tip extends towards the noduli. The name gorget is taken from the name for a steel collar used to protect one’s throat. The position of the gorget corresponds to the throat if the vest and epaulette are respectively taken to be body and shoulders. The gorget corresponds to part of the inferior region of the vmpr of Otsuna and Ito (2006) and to the supracommissural ventromedial cerebrum (Ito et al., 2014).

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inferior bridge [FBbt_00040050]

Posterior-most synaptic neuropil domain of the midline. It is the only synaptic neuropil domain outside of the central complex that is fused across the midline. It is located behind the fan-shaped body and below the protocerebral bridge. The IB corresponds to part of the superior spsl of Otsuna and Ito (2006). The IB also corresponds to the ventral part of the caudalcentral protocerebrum (CCP) of Chiang et al., (2011) and to part of the posterior inferior protocerebrum (Ito et al., 2014).

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intermediate tectulum [FBbt_00047519]

Adult neuropil region spanning the three thoracic neuromeres, ventral to the neck, wing and haltere neuropils of the upper tectulum and dorsal to the lower tectulum (Namiki et al., 2018; Court et al., 2020). It extends from the prothoracic medial ventral association center to the posterior margin of the mesothoracic neuromere at the commissure of fine fibers (Court et al., 2020). Referred to as ’tectulum’ by Namiki et al. (2018), but does not exactly correspond to Power’s (1948) tectulum (FBbt:00007727). Originally named ‘upper tectulum’, as this was the upper of two ’tectulum’ layers in Namiki et al. (2018), but this region is the intermediate layer of Court et al. (2020).

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labial sensory center [FBbt_00040055]

Region that spans the labial and maxillary neuromeres of the adult brain and contains the terminals of sensory neurons that enter via the posterior and intermediate posterior roots of the maxillary-labial nerve (Miyazaki and Ito, 2010; Kendroud et al., 2018), including some gustatory neurons of the labellum (Miyazaki and Ito, 2010). Three distinct subregions can be identified: a posterior zone (LS1), a ventral protrusion on the posterior side of LS1 (LS2) and an anterior medial zone (LS3) (Miyazaki and Ito, 2010). It develops from the anterior part of the larval ventromedial sensory center (the posterior part is pinched off and remains in the ventral nerve cord) (Kendroud et al., 2018).

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larval anterior central sensory compartment [FBbt_00051407]

Sensory compartment of the larval central nervous system that is found mainly within the dorsal part of the ventromedial neuropil domain of the tritocerebrum and mandibular neuromere (Kendroud et al., 2018). It contains sensory afferents of neurons from the pharyngeal and maxillary-labial nerves (Kendroud et al., 2018; Miroschnikow et al., 2018). AC of Miroschnikow et al. (2018) and ACSC of Kendroud et al. (2018) refer to approximately the same anatomy, but boundaries may not precisely correspond - see author response of Miroschnikow et al. (2018). Notably ACpl was not identified by Kendroud et al. (2018) (Miroschnikow et al., 2018).

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larval anterior central sensory compartment anterior lateral region [FBbt_00048495]

Small region of the larval anterior central sensory compartment that is just posterior to the antennal lobe (Miroschnikow et al., 2018). It contains the terminals of neurons from the dorsal organ ganglion that enter the CNS via the antennal-pharyngeal nerve (Miroschnikow et al., 2018). ACSCal of Kendroud et al. (2018) - FBrf0237251 is larger, extends further medially and contains many DPS neuron terminals. This region, defined by Miroschnikow et al. (2018) contains only external (DOG) neuron terminals. The DPS neuron terminals of Kendroud et al. (2018) are probably part of the posterior region (as defined by Miroschnikow et al., 2018), which extends further anteriorly along the lateral border of the anterior medial region, compared to the posterior region of Kendroud et al. (2018), and consists of external and pharyngeal neuron terminals.

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larval anterior central sensory compartment anterior medial region [FBbt_00048492]

Anterior medial region of the larval anterior central sensory compartment (Kendroud et al., 2018; Miroschnikow et al., 2018). It contains the terminals of sensory neurons from the enteric nervous system that enter the CNS via the medial root of the antennal-pharyngeal nerve (Kendroud et al., 2018; Miroschnikow et al., 2018).

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larval anterior central sensory compartment posterior lateral region [FBbt_00048497]

Region of the larval anterior central sensory compartment that is lateral to the posterior region (Miroschnikow et al., 2018). It contains the terminals of sensory neurons that enter the CNS via the antennal and maxillary nerves (Miroschnikow et al., 2018). Identified based on synaptic clustering of sensory neurons in a first instar EM volume (Miroschnikow et al., 2018). This region was not identified by Kendroud et al. (2018) - FBrf0237251 (Miroschnikow et al., 2018).

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larval anterior central sensory compartment posterior region [FBbt_00048496]

Relatively large region of the larval anterior central sensory compartment, found between the anterior medial and posterior lateral regions (Miroschnikow et al., 2018). It contains the terminals of sensory neurons that enter the CNS via the antennal and maxillary nerves (Miroschnikow et al., 2018). ACSCp of Kendroud et al. (2018) - FBrf0237251 is smaller and does not extend as far anteriorly as this region, defined by Miroschnikow et al. (2018). The DPS neuron terminals in the ACSCal of Kendroud et al. (2018) are probably part of the this region.

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larval anterior ventral sensory compartment [FBbt_00051408]

Sensory compartment of the larval central nervous system that is found mainly within a superficial (ventral) region of the ventromedial neuropil domain of the tritocerebrum and mandibular neuromere (Kendroud et al., 2018). It contains sensory afferents of neurons from the pharyngeal and maxillary-labial nerves (Kendroud et al., 2018; Miroschnikow et al., 2018). AV of Miroschnikow et al. (2018) and AVSC of Kendroud et al. (2018) refer to approximately the same anatomy, but boundaries may not precisely correspond - see author response of Miroschnikow et al. (2018).

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larval anterior ventral sensory compartment anterior region [FBbt_00048493]

Anterior region of the larval anterior ventral sensory compartment. It contains the terminals of enteric neurons from the frontal connective that enter via the medial root of the pharyngeal nerve (Kendroud et al., 2018; Miroschnikow et al., 2018). It is also contributed to by neurons of the dorsal pharyngeal sense organ that follow the anterior root of the pharyngeal nerve (Kendroud et al., 2018; Miroschnikow et al., 2018).

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larval anterior ventral sensory compartment posterior region [FBbt_00048494]

Posterior region of the larval anterior ventral sensory compartment. It is formed by superficial branches of the anterior and intermediate maxillary-labial nerve roots (Kendroud et al., 2018; Miroschnikow et al., 2018).

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larval central sensory compartment [FBbt_00051404]

Sensory compartment of the larval central nervous system that is found mainly within the central neuropil domain (Kendroud et al., 2018). In the anterior prothoracic neuromere, it narrows to a thin bundle, but continues to extend anteriorly through the gnathal neuromeres (Kendroud et al., 2018). Anteriorly, in the tritocerebrum, it contains the projections of a small bundle of axons from the antennal nerve, foreshadowing the position of the adult antennal mechanosensory and motor center (Kendroud et al., 2018). It contains the terminals of chordotonal organ neurons (Kendroud et al., 2018).

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larval dorsomedial sensory compartment [FBbt_00051406]

Sensory compartment of the larval central nervous system that is found mainly within the dorsomedial neuropil domain (Kendroud et al., 2018). In the anterior prothoracic neuromere, it narrows to a thin bundle that continues to extend anteriorly through the gnathal neuromeres, but does not appear to receive any projections from sensory neurons of the maxillary-labial nerve or antennal-pharyngeal nerve (Kendroud et al., 2018).

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larval optic focus [FBbt_00007131]

A synaptic neuropil domain of the larval brain formed during larval stages by axons originating from the lobula primordium in the optic lobe and dorso-lateral protocerebrum. These axons form terminal branches lateral to the borders of the centro-posterior lateral and baso-lateral compartments which then become enclosed by a glial sheath, forming this compartment.

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larval optic neuropil [FBbt_00048289]

Small neuropil compartment of the larval optic lobe that contains the axons of photoreceptors. It is the first center for visual processing in the larval brain. It is largely surrounded by the outer optic anlage at earlier developmental stages and becomes sandwiched between the developing proximal medulla and the inner optic anlage by third instar. It is incorporated into the adult optic lobe as the accessory medulla.

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larval ventromedial sensory compartment [FBbt_00048498]

Sensory compartment of the larval central nervous system that extends from the maxillary neuromere into the ventral nerve cord, largely overlapping the ventromedial neuropil domain (Kendroud et al., 2018). It contains the terminals of sensory neurons that enter the CNS via the antennal-pharyngeal, maxillary-labial, prothoracic accessory and lateropharyngeal nerves (Kendroud et al., 2018; Miroschnikow et al., 2018). VM of Miroschnikow et al. (2018) and VMSC of Kendroud et al. (2018) refer to approximately the same anatomy, but boundaries may not precisely correspond - see author response of Miroschnikow et al. (2018).

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lobe system of adult mushroom body [FBbt_00013688]

The adult mushroom body lobe system consists of a dorsal branch composed of two intertwined lobes (alpha and alpha’) and a medial branch consisting of three parallel lobes (beta, beta’ and gamma) (Aso et al., 2014). The lobes can be divided into layers, which form strata spanning the length of each lobe, and slices, which are full width subdivisions of the length of each lobe (Aso et al., 2014).

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lobe system of larval mushroom body [FBbt_00110641]

The larval mushroom body lobe system consists of a dorsal branch and a medial branch (Pauls et al., 2010). At third instar, both lobes comprise three types of Kenyon cells: embryonic-born gamma neurons, larval-born gamma neurons and larval born alpha’/beta’ neurons (Pauls et al., 2010).

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lower tectulum [FBbt_00047174]

Ventralmost layer of the tectulum that extends posteriorly from the prothoracic medial ventral association center to the posterior margin of the mesothoracic neuromere at the commissure of fine fibers (Court et al., 2020). It is bordered ventrally by the ventral median tract of ventral cervical fasciculus and laterally by the dorsal lateral tract of ventral cervical fasciculus (Court et al., 2020). The neuropil referred to as ovoid in Namiki et al. (2018) supplementary file 1 has an identical innervation profile to lower tectulum in Figure 5, so I have added this as a synonym [FBC:CP].

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medial lobe of larval mushroom body [FBbt_00110188]

The medial lobe of the larval mushroom body. It is associated with appetitive memory (Eschbach et al., 2020). At third instar, the medial lobe comprise three types of Kenyon cells: embryonic-born gamma neurons, larval-born gamma neurons and larval born alpha’/beta’ neurons (Pauls et al., 2010).

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mushroom body calyx [FBbt_00003685]

A synaptic neuropil domain containing dendrites of Kenyon cells and receiving sensory interneuron afferents, mainly from the antennal lobes (Ito et al., 2014; Saumweber et al., 2018). It is located on the posterior side of the brain, close to the cortex where the cell bodies of the Kenyon cells are located (Lee et al., 1999; Saumweber et al., 2018). The peduncle extends anteriorly from the calyx to the base of the lobes (Ito et al., 2014; Saumweber et al., 2018).

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nodulus [FBbt_00003680]

Paired synaptic neuropil domain of the adult brain located just caudal to the ellipsoid body and ventral to the fan-shaped body, on either side of the midline (Hanesch et al., 1989). There are three of these structures, stacked on top of each other from dorsal to ventral, and at least two can be further divided into compartments (Wolff et al., 2015; Wolff and Rubin, 2018). There is asymmetry between the noduli, with one set always lying slightly more anterior than the other (Ito et al., 2014). Ito et al. (2014) state that there are four subunits of one nodulus per hemisphere, but Wolff et al. (2015) and Wolff and Rubin (2018) class the noduli as three distinct units and count ‘subunit IV’ as part of nodulus 3; here we follow the Wolff nomenclature.

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posterior lateral protocerebrum [FBbt_00040044]

A bilaterally paired synaptic neuropil domain of the adult that contains many glomeruli and is located behind the posterior ventrolateral protocerebrum (PVLP) and above the wedge. The mid-level of the posterior lateral protocerebrum (PLP) is separated from the PVLP by the great commissure, but above and below this the two neuropils are contiguous. The PLP houses many optic glomeruli formed by the terminals of neurons projecting from the optic lobe, primarily from the lobula plate. The boundary with the PVLP is defined by the boundary between these glomeruli that have different origins (lobula or lobula plate). The PLP corresponds to almost all of the plpr of Otsuna and Ito (2006) and to the caudal ventrolateral protocerebrum (CVLP) and lateral part of the superpeduncular protocerebrum (SPP) of Chiang et al., (2011) (Ito et al., 2014).

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posterior maxillary sensory center [FBbt_00040056]

Region spanning the adult tritocerebrum and mandibular neuromere that contains terminals of sensory neurons that enter the brain via the anterior intermediate root of the maxillary-labial nerve and the anterior and medial roots of the pharyngeal nerve (Miyazaki and Ito, 2010). Five distinct subregions can be identified: a horn-like protrusion in the dorsolateral GNG (PMS1), a dorsal medial region (PMS2), a ventral medial region (PMS3), a zone near the entry point of the labial nerve (PMS4) and a zone ventral to PSM3 (PSM5) (Miyazaki and Ito, 2010). It arises from the larval anterior central sensory compartment (Kendroud et al., 2018). Bitter-sensitive neurons of the labellum sensilla (identified with Gr32a-, Gr66a- and NV4-GAL4) terminate in PMS1-3 zones. Subsets of Gr66a-GAL4 positive neurons terminated in specific subareas of these zones. Water-sensitive neurons (identified with NP1017-GAL4) and sugar-sensitive neurons (identified with Gr5a-GAL4) terminate in PMS4-5 zones (Miyazaki and Ito, 2010).

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posterior slope [FBbt_00040072]

Synaptic neuropil domain of the adult brain that is the inferior (ventral) part of the posterior cerebral ganglion, covering the area between the inferior bridge and the gnathal ganglion with its superior part lying behind the ventral complex. It contains extensive arborizations of ascending and descending neurons. Its superior boundary is the level above which such arborizations do not occur. It also contains the terminals of axons from the ocellar ganglia, projecting via the ocellar nerve. The ventral complex corresponds to the caudal medial protocerebrum (CMP) and possibly includes part of the ventromedial protocerebrum (VMP) of Chiang et al., (2011) (Ito et al., 2014).

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posterior ventrolateral protocerebrum [FBbt_00040042]

A glomerular, bilaterally paired synaptic neuropil domain lying in front of the posterior lateral protocerebrum (PLP), and above the wedge. The great commissure is at the boundary in the mid-level between the PLVP and PLP. It is contiguous with posterior lateral protocerebrum (PLP), which lies behind it. It houses many optic glomeruli formed by the terminals of neurons projecting from the optic lobe, primarily from the lobula. The boundary with the PLP, except at mid-level, is defined as the boundary between these glomeruli with different origins (lobula or lobula plate).

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protocerebral bridge [FBbt_00003668]

A handle bar-shaped synaptic neuropil located just posterior to the fan-shaped body. Its lateral edge ends at the posterior end of the inferior clamp (ICL) near the medial equatorial fascicle (MEF). A row of 18 connected slices (9 on each side of the midline, numbered 1-9 from medial to lateral) that forms a dorso-posteriorly located part of the central complex embedded in the cortex between the calyces of the two mushroom bodies. The identification of the most medial slice (slice 1) by Wolff et al. (2015) meant that the domain that was previously called slice 1 corresponds in fact to slice 2. Each of the two neighboring slices (2-3, 4-5, 6-7, 8-9) are associated more closely because small-field columnar neurons innervate the fan-shaped body via the protocerebral bridge, and these neurons are generated by the same neuroblasts, forming four groups on each side of the midline, from lateral to medial: segment pair W, X, Y and Z (Boyan and Williams et al., 2011; Ito and Awasaki, 2008).

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prow [FBbt_00040051]

Anteriormost and superior synaptic neuropil domain below the esophagus (Ito et al., 2014). It lies inferior and anterior to the opening of the esophageal foramen (Ito et al., 2014). It houses the superior pharyngeal sensory center (SPhS), containing the terminals of peripheral axons from the pharyngeal nerve (Ito et al., 2014). It forms the ventral part of the tritocerebrum, developing from the ventromedial domain of the larval tritocerebrum (Hartenstein et al., 2018). The name ‘prow’ was taken from the anterior-most part of the hull of a boat. It is part of the ventral cerebral ganglion, which is included in the adult subesophageal zone (old subesophageal ganglion, or SOG) (Ito et al., 2014). The prow also corresponds to the dorsoanterior part of the subesophageal ganglion (SOG) of Chiang et al., (2011) and to the part of the anterior periesophageal neuropils (Ito et al., 2014).

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saddle [FBbt_00045048]

Synaptic neuropil domain covering the dorsal and posterior surface of the adult gnathal ganglia. It contains the antennal mechanosensory and motor center (AMMC). The saddle corresponds to the antennal mechanosensory and motor center (AMMC) of Chiang et al., (2011) and to the lateral and ventromedial periesophageal neuropils (Ito et al., 2014).

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superior intermediate protocerebrum [FBbt_00045032]

A small synaptic neuropil domain of the adult located around and posterior to the mushroom body vertical lobe, in front of the superior fiber system and above the superior clamp. This domain is rich in loose fibers that project from the anterior optic tubercle in a medial-posterior direction. It also houses the arborizations of many neurons that connect with the vertical lobes. The SIP encompasses the ring neuropil, which corresponds to the terminals of the mlALT neurons, which wrap around the distal tip region of the mushroom body vertical lobe (Ito et al., 2014). Different regions of the SIP correspond to the subdivisions of the smpr and impr (Otsuna and Ito, 2006). The anterior and posterior regions of the superior SIP match part of smpr; the anterior and posterior regions of the inferior SIP match part of impr (Ito et al., 2014). The SIP correspond to the medial part of the dorsolateral protocerebrum (DLP) and the frontal superpeduncular protocerebrum (FSPP) of Chiang et al., (2011).

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superior lateral protocerebrum [FBbt_00007054]

Lateral synaptic neuropil domain of the adult superior neuropils. It lies behind the anterior optic tubercle, in front of the mushroom body calyx and above the superior clamp and lateral horn. Its boundary with the anterior optic tubercle (AOTU), mushroom body calyx and lateral horn is demarcated by the extent of arborization of visual projection neurons and antennal lobe projection neurons. Boundaries with the superior clamp, anterior and posterior ventro-lateral protocerebrum are defined using clearly distinguishable fiber bundles. Boundaries defined by Ito et al. (2014) (used to define this term) differ slightly from those defined for slpr in Otsuna and Ito, 2006. The anterior superior SLP corresponds to mslpr and the posterior superior SLP to pslpr of Otsuna and Ito (2006). The SLP also corresponds to the lateral part of the dorsolateral protocerebrum (DLP) and lateral part of the inner dorsolateral protocerebrum (IDLP) of Chiang et al., (2011) (Ito et al., 2014).

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superior medial protocerebrum [FBbt_00007055]

Medial synaptic neuropil domain of the adult superior neuropils that lies above the area flanked by the mushroom lobes, pedunculus, and calyx. It is separated from the pedunculus by the superior clamp and insulated from the medial lobe by the crepine. The fan-shaped body protrudes deeply into this neuropil, separating it into anterior (ASMP) and posterior (PSMP) regions. Different regions of the SMP correspond to the subdivisions of the smpr and impr (Otsuna and Ito, 2006). The anterior and posterior regions of the superior SMP match part of smpr; the anterior and posterior regions of the inferior SMP match part of impr. The SMP also corresponds to the superior dorsofrontal protocerebrum (SDFP) and to the medial part of the inner dorsolateral protocerebrum (IDLP) of Chiang et al., (2011) (Ito et al., 2014).

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thoracic intermediate neuropil [FBbt_00049995]

Region of adult leg neuropil between the ventral association center and the tectulum that occupies most of the central third of the dorsoventral area (in transverse section) of each thoracic neuromere (Court et al., 2020). It contains the dendritic branches of leg motor neurons, premotor interneurons and sensory afferents from leg sensory neurons (Court et al., 2020).

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upper tectulum [FBbt_00049994]

Dorsalmost layer of the tectulum that sits dorsal to the dorsal medial tract and haltere tract (Court et al., 2020). The upper tectulum can be further segregated on the basis of the synapse rich neuropil regions into three segment-specific neuropils; a prothoracic neck neuropil, a mesothoracic wing neuropil and a metathoracic haltere neuropil (Court et al., 2020).

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vertical lobe of larval mushroom body [FBbt_00110189]

The vertical lobe of the larval mushroom body (Pauls et al., 2010). At third instar, the vertical lobe comprise three types of Kenyon cells: embryonic-born gamma neurons, larval-born gamma neurons and larval born alpha’/beta’ neurons (Pauls et al., 2010).

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vest [FBbt_00040041]

Bilaterally paired synaptic neuropil domain that is the largest and most medial domain of the ventral complex. Its inferior (ventral) boundary with the saddle is demarcated by a glial sheath and the medial and lateral sides are flanked respectively by the esophagus and inferior fiber system. The vest corresponds to part of the inferior region of the vmpr of Otsuna and Ito (2006) and the part of the precommissural ventromedial cerebrum (Ito et al., 2014).

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wedge [FBbt_00045027]

An aglomerular, bilaterally paired synaptic neuropil domain that is the inferior-most domain of the ventrolateral neuropils, lying between the anterior and posterior ventrolateral protocerebrum (AVLP and PVLP) and posteriorlateral protocerebrum (PLP), and the saddle and gnathal ganglion. The wedge is lateral to the inferior fiber system and vest. It receives synaptic input from the saddle and the antennal mechanosensory and motor center (AMMC) within it. This includes direct sensory input from antennal mechanosensory neurons that also innervate the AMMC. The anterior wedge corresponds to the inferior part of the vlpr of Otsuna and Ito (2006); the posterior wedge corresponds to part of the plpr (Ito et al., 2014).

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