Vertical Lobe Research Articles

Neural Organization of A3 Mushroom Body Extrinsic Neurons in the Honeybee Brain.

In the insect brain, the mushroom body is a higher order brain area that is key to memory formation and sensory processing. Mushroom body (MB) extrinsic neurons leaving the output region of the MB, the lobes and the peduncle, are thought to be especially important in these processes. In the honeybee brain, a distinct class of MB extrinsic neurons, A3 neurons, are implicated in playing a role in learning. Their MB arborisations are either restricted to the lobes and the peduncle, here called A3 lobe connecting neurons, or they provide feedback information from the lobes to the input region of the MB, the calyces, here called A3 feedback neurons. In this study, we analyzed the morphology of individual A3 lobe connecting and feedback neurons using confocal imaging. A3 feedback neurons were previously assumed to innervate each lip compartment homogenously. We demonstrate here that A3 feedback neurons do not innervate whole subcompartments, but rather innervate zones of varying sizes in the MB lip, collar, and basal ring. We describe for the first time the anatomical details of A3 lobe connecting neurons and show that their connection pattern in the lobes resemble those of A3 feedback cells. Previous studies showed that A3 feedback neurons mostly connect zones of the vertical lobe that receive input from Kenyon cells of distinct calycal subcompartments with the corresponding subcompartments of the calyces. We can show that this also applies to the neck of the peduncle and the medial lobe, where both types of A3 neurons arborize only in corresponding zones in the calycal subcompartments. Some A3 lobe connecting neurons however connect multiple vertical lobe areas. Contrarily, in the medial lobe, the A3 neurons only innervate one division. We found evidence for both input and output areas in the vertical lobe. Thus, A3 neurons are more diverse than previously thought. The understanding of their detailed anatomy might enable us to derive circuit models for learning and memory and test physiological data.

Calcium imaging method to visualize the spatial patterns of neural responses in the pygmy squid, Idiosepius paradoxus, central nervous system

BackgroundCephalopods exhibit unique behaviors such as camouflage and tactile learning. The brain functions correlated to these behaviors have long been analyzed through behavioral observations of animals subject to surgical manipulation or electrical stimulation of brain lobes. However, physiological methods have rarely been introduced to investigate the functions of each individual lobe, though physiological work on giant axons and slices of the vertical lobe system of the cephalopods have provided deep insights into ion conductance of nerves and long-term synaptic plasticity. The lack of in vivo physiological work is partly due to difficulties in immobilizing the brain which is contained within the soft body and applying calcium indicators to the cephalopod central nervous system. New methodWe here present a calcium imaging method to visualize neural responses in the central nervous system of the smallest squid, Idiosepius paradoxus. ResultsWe injected calcium indicator Cal-520 into the brachial lobes and revealed a spatiotemporal pattern of neural responses to the electrical stimulations of the axial nerve cord in the first arm. Comparison with existing methodsWe established a method to immobilize the central nervous system which is contained within the soft body and record the calcium responses from the intact central nervous system. ConclusionsOur method provides a novel approach to investigate the mechanisms of how the characteristic organization of the cephalopod brain functions to induce their unique behaviors.

A Tyrosine-Hydroxylase Characterization of Dopaminergic Neurons in the Honey Bee Brain.

Dopamine (DA) plays a fundamental role in insect behavior as it acts both as a general modulator of behavior and as a value system in associative learning where it mediates the reinforcing properties of unconditioned stimuli (US). Here we aimed at characterizing the dopaminergic neurons in the central nervous system of the honey bee, an insect that serves as an established model for the study of learning and memory. We used tyrosine hydroxylase (TH) immunoreactivity (ir) to ensure that the neurons detected synthesize DA endogenously. We found three main dopaminergic clusters, C1–C3, which had been previously described; the C1 cluster is located in a small region adjacent to the esophagus (ES) and the antennal lobe (AL); the C2 cluster is situated above the C1 cluster, between the AL and the vertical lobe (VL) of the mushroom body (MB); the C3 cluster is located below the calyces (CA) of the MB. In addition, we found a novel dopaminergic cluster, C4, located above the dorsomedial border of the lobula, which innervates the visual neuropils of the bee brain. Additional smaller processes and clusters were found and are described. The profuse dopaminergic innervation of the entire bee brain and the specific connectivity of DA neurons, with visual, olfactory and gustatory circuits, provide a foundation for a deeper understanding of how these sensory modules are modulated by DA, and the DA-dependent value-based associations that occur during associative learning.

Context-dependent memory traces in the crab’s mushroom bodies: Functional support for a common origin of high-order memory centers

The hypothesis of a common origin for the high-order memory centers in bilateral animals is based on the evidence that several key features, including gene expression and neuronal network patterns, are shared across several phyla. Central to this hypothesis is the assumption that the arthropods' higher order neuropils of the forebrain [the mushroom bodies (MBs) of insects and the hemiellipsoid bodies (HBs) of crustaceans] are homologous structures. However, even though involvement in memory processes has been repeatedly demonstrated for the MBs, direct proof of such a role in HBs is lacking. Here, through neuroanatomical and immunohistochemical analysis, we identified, in the crab Neohelice granulata, HBs that resemble the calyxless MBs found in several insects. Using in vivo calcium imaging, we revealed training-dependent changes in neuronal responses of vertical and medial lobes of the HBs. These changes were stimulus-specific, and, like in the hippocampus and MBs, the changes reflected the context attribute of the memory trace, which has been envisioned as an essential feature for the HBs. The present study constitutes functional evidence in favor of a role for the HBs in memory processes, and provides key physiological evidence supporting a common origin of the arthropods' high-order memory centers.

Behavioral development in embryonic and early juvenile cuttlefish (Sepia officinalis)

Though a mollusc, the cuttlefish Sepia officinalis possesses a sophisticated brain, advanced sensory systems, and a large behavioral repertoire. Cuttlefish provide a unique perspective on animal behavior due to their phylogenic distance from more traditional (vertebrate) models. S. officinalis is well-suited to addressing questions of behavioral ontogeny. As embryos, they can perceive and learn from their environment and experience no direct parental care. A marked progression in learning and behavior is observed during late embryonic and early juvenile development. This improvement is concomitant with expansion and maturation of the vertical lobe, the cephalopod analog of the mammalian hippocampus. This review synthesizes existing knowledge regarding embryonic and juvenile development in this species in an effort to better understand cuttlefish behavior and animal behavior in general. It will serve as a guide to future researchers and encourage greater awareness of the utility of this species to behavioral science.

Dopamine- and Tyrosine Hydroxylase-Immunoreactive Neurons in the Brain of the American Cockroach, Periplaneta americana.

The catecholamine dopamine plays several vital roles in the central nervous system of many species, but its neural mechanisms remain elusive. Detailed neuroanatomical characterization of dopamine neurons is a prerequisite for elucidating dopamine’s actions in the brain. In the present study, we investigated the distribution of dopaminergic neurons in the brain of the American cockroach, Periplaneta americana, using two antisera: 1) an antiserum against dopamine, and 2) an antiserum against tyrosine hydroxylase (TH, an enzyme required for dopamine synthesis), and identified about 250 putatively dopaminergic neurons. The patterns of dopamine- and TH-immunoreactive neurons were strikingly similar, suggesting that both antisera recognize the same sets of “dopaminergic” neurons. The dopamine and TH antibodies intensively or moderately immunolabeled prominent brain neuropils, e.g. the mushroom body (memory center), antennal lobe (first-order olfactory center) and central complex (motor coordination center). All subdivisions of the mushroom body exhibit both dopamine and TH immunoreactivity. Comparison of immunolabeled neurons with those filled by dye injection revealed that a group of immunolabeled neurons with cell bodies near the calyx projects into a distal region of the vertical lobe, which is a plausible site for olfactory memory formation in insects. In the antennal lobe, ordinary glomeruli as well as macroglomeruli exhibit both dopamine and TH immunoreactivity. It is noteworthy that the dopamine antiserum labeled tiny granular structures inside the glomeruli whereas the TH antiserum labeled processes in the marginal regions of the glomeruli, suggesting a different origin. In the central complex, all subdivisions excluding part of the noduli and protocerebral bridge exhibit both dopamine and TH immunoreactivity. These anatomical findings will accelerate our understanding of dopaminergic systems, specifically in neural circuits underlying aversive memory formation and arousal, in insects.

The antidepressant venlafaxine may act as a neurodevelopmental toxicant in cuttlefish (Sepia officinalis)

The Serotonin/Norepinephrine Reuptake Inhibitor (SNRI) antidepressant venlafaxine (VEN, Effexor®) has become one of the most common antidepressants detected in North American and European streams. Mammalian research has established that VEN exposure is associated with a range of structural, neurochemical, and functional alterations of the brain in adults and newborns. However, the neurodevelopmental effects of VEN on non-target organisms have never been investigated. The aim of our research was to decrease this gap in knowledge by characterizing the effects of VEN exposure on a cephalopod mollusk, the common cuttlefish Sepia officinalis. This species inhabits VEN-contaminated waters and possesses an unusually sophisticated brain. These characteristics render it a unique invertebrate species for studying the neurodevelopmental effects of VEN. Cuttlefish were exposed to environmentally-relevant concentrations of VEN (Measured concentrations ≈5 and 100ngL−1) or to filtered natural seawater (control) in a closed-loop system with regular water changes during the first 20days after hatching. We evaluated brain maturation as well as neurochemical changes and behavioral performances during this critical period of development. Our results show that both VEN-exposed groups exhibited a decrease in norepinephrine levels, along with a reduction in the relative number of glutamate NMDA-like receptors binding sites in the group exposed to 5ngL−1 of VEN after 20days of exposure. Brain regional changes in cellular proliferation were observed in VEN-exposed groups in the vertical lobe (i.e. a key structure involved in cognitive processes) and in the optic lobes (i.e. main visual processing centers) in the absence of significant change in their volume. Along with these neurodevelopmental changes, 20days of exposure to 100ngL−1 of VEN was associated with a decrease in camouflage ability. Overall, our study suggests that VEN is a neurodevelopmental toxicant in non-target aquatic organisms at environmentally-relevant concentrations.

Three-dimensional brain atlas of pygmy squid, Idiosepius paradoxus, revealing the largest relative vertical lobe system volume among the cephalopods.

Cephalopods have the largest and most complex nervous system of all invertebrates, and the brain-to-body weight ratio exceeds those of most fish and reptiles. The brain is composed of lobe units, the functions of which have been studied through surgical manipulation and electrical stimulation. However, how information is processed in each lobe for the animal to make a behavioral decision has rarely been investigated. To perform such functional analyses, it is necessary to precisely describe how brain lobes are spatially organized and mutually interconnected as a whole. We thus made three-dimensional digital brain atlases of both hatchling and juvenile pygmy squid, Idiosepius paradoxus. I. paradoxus is the smallest squid and has a brain small enough to scan as a whole region in the field-of-view of a low-magnification laser scan microscope objective. Precise analyses of the confocal images of the brains revealed one newly identified lobe and also that the relative volume of the vertical lobe system, the higher association center, in the pygmy squid represents the largest portion compared with the cephalopod species reported previously. In addition, principal component analyses of relative volumes of lobe complexes revealed that the organization of I. paradoxus brain is comparable to those of Decapodiformes species commonly used to analyze complex behaviors such as Sepia officinalis and Sepioteuthis sepioidea. These results suggest that the pygmy squid can be a good model to investigate the brain functions of coleoids utilizing physiological methods. J. Comp. Neurol. 524:2142-2157, 2016. © 2016 Wiley Periodicals, Inc.

Pain in parallel

Pain in parallel

Convergent evolution of complex brains and high intelligence.

Within the animal kingdom, complex brains and high intelligence have evolved several to many times independently, e.g. among ecdysozoans in some groups of insects (e.g. blattoid, dipteran, hymenopteran taxa), among lophotrochozoans in octopodid molluscs, among vertebrates in teleosts (e.g. cichlids), corvid and psittacid birds, and cetaceans, elephants and primates. High levels of intelligence are invariantly bound to multimodal centres such as the mushroom bodies in insects, the vertical lobe in octopodids, the pallium in birds and the cerebral cortex in primates, all of which contain highly ordered associative neuronal networks. The driving forces for high intelligence may vary among the mentioned taxa, e.g. needs for spatial learning and foraging strategies in insects and cephalopods, for social learning in cichlids, instrumental learning and spatial orientation in birds and social as well as instrumental learning in primates.

Ancestral role of Pax2/5/8 in molluscan brain and multimodal sensory system development.

BackgroundMollusks represent the largest lophotrochozoan phylum and exhibit highly diverse body plans. Previous studies have demonstrated that transcription factors such as Pax genes play important roles during their development. Accordingly, in ecdysozoan and vertebrate model organisms, orthologs of Pax2/5/8 are among others involved in the formation of the midbrain/hindbrain boundary, the auditory/geosensory organ systems, and the excretory system.MethodsPax2/5/8 expression was investigated by in situ hybridization during the development of representatives of the two major molluscan subclades, Aculifera and Conchifera.ResultsCompared to the investigated polyplacophoran and bivalve species that lack larval statocysts as geosensory organs and elaborate central nervous systems (CNS), cephalopods possess highly centralized brains and statocysts. Pax2/5/8 is expressed in regions where sensory cells develop subsequently during ontogenesis. Expression domains include esthetes and the ampullary system in polyplacophorans as well as the eyes of cephalopods. No Pax2/5/8 expression was observed in the less centralized CNS of bivalve, polyplacophoran, and gastropod embryos, thus arguing for a loss of Pax2/5/8 involvement in CNS development in these lineages. In contrast, Pax2/5/8 is expressed among others in brain lobes along the trajectory of the esophagus that divides the cephalopod brain.ConclusionsOur results, along with those on Otx- and Hox-gene expression, demonstrate that the cephalopod condition is similar to that in mouse and fruit fly, with Otx being expressed in the anterior-most brain region (except for the vertical lobe) and a Pax2/5/8 expression domain separating the Otx-domain from a Hox-gene expressing posterior brain region. Thus, Pax2/5/8 appears to have been recruited independently into regionalization of non-homologous complex brains of organisms as different as squid, fruit fly, and mouse. In addition, Pax2/5/8 is expressed in multimodal sensory systems in mollusks such as the esthetes and the ampullary system of polyplacophorans as well as the eyes of cephalopods. Pax2/5/8-expressing cells are present in regions where the future sensory cells such as the polyplacophoran esthetes are situated and hence Pax2/5/8 expression probably predates sensory cell development during ontogeny. In mollusks, Pax2/5/8 is only expressed in derivatives of the ectoderm and hence an ancestral role in molluscan ectoderm differentiation is inferred.

The vertical lobe of cephalopods: an attractive brain structure for understanding the evolution of advanced learning and memory systems.

In this review we show that the cephalopod vertical lobe (VL) provides a good system for assessing the level of evolutionary convergence of the function and organization of neuronal circuitry for mediating learning and memory in animals with complex behavior. The pioneering work of JZ Young described the morphological convergence of the VL with the mammalian hippocampus, cerebellum and the insect mushroom body. Studies in octopus and cuttlefish VL networks suggest evolutionary convergence into a universal organization of connectivity as a divergence-convergence ('fan-out fan-in') network with activity-dependent long-term plasticity mechanisms. Yet, these studies also show that the properties of the neurons, neurotransmitters, neuromodulators and mechanisms of long-term potentiation (LTP) induction and maintenance are highly variable among different species. This suggests that complex networks may have evolved independently multiple times and that even though memory and learning networks share similar organization and cellular processes, there are many molecular ways of constructing them.

The gyri of the octopus vertical lobe have distinct neurochemical identities

ABSTRACTThe cephalopod vertical lobe is the largest learning and memory structure known in invertebrate nervous systems. It is part of the visual learning circuit of the central brain, which also includes the superior frontal and subvertical lobes. Despite the well‐established functional importance of this system, little is known about neuropil organization of these structures and there is to date no evidence that the five longitudinal gyri of the vertical lobe, perhaps the most distinctive morphological feature of the octopus brain, differ in their connections or molecular identities. We studied the histochemical organization of these structures in hatchling and adult Octopus bimaculoides brains with immunostaining for serotonin, octopus gonadotropin‐releasing hormone (oGNRH), and octopressin‐neurophysin (OP‐NP). Our major finding is that the five lobules forming the vertical lobe gyri have distinct neurochemical signatures. This is most prominent in the hatchling brain, where the median and mediolateral lobules are enriched in OP‐NP fibers, the lateral lobule is marked by oGNRH innervation, and serotonin immunostaining heavily labels the median and lateral lobules. A major source of input to the vertical lobe is the superior frontal lobe, which is dominated by a neuropil of interweaving fiber bundles. We have found that this neuropil also has an intrinsic neurochemical organization: it is partitioned into territories alternately enriched or impoverished in oGNRH‐containing fascicles. Our findings establish that the constituent lobes of the octopus superior frontal–vertical system have an intricate internal anatomy, one likely to reflect the presence of functional subsystems within cephalopod learning circuitry. J. Comp. Neurol. 523:1297–1317, 2015. © 2015 Wiley Periodicals, Inc.

Molecular Evidence for Convergence and Parallelism in Evolution of Complex Brains of Cephalopod Molluscs: Insights from Visual Systems.

Coleoid cephalopods show remarkable evolutionary convergence with vertebrates in their neural organization, including (1) eyes and visual system with optic lobes, (2) specialized parts of the brain controlling learning and memory, such as vertical lobes, and (3) unique vasculature supporting such complexity of the central nervous system. We performed deep sequencing of eye transcriptomes of pygmy squids (Idiosepius paradoxus) and chambered nautiluses (Nautilus pompilius) to decipher the molecular basis of convergent evolution in cephalopods. RNA-seq was complemented by in situ hybridization to localize the expression of selected genes. We found three types of genomic innovations in the evolution of complex brains: (1) recruitment of novel genes into morphogenetic pathways, (2) recombination of various coding and regulatory regions of different genes, often called "evolutionary tinkering" or "co-option", and (3) duplication and divergence of genes. Massive recruitment of novel genes occurred in the evolution of the "camera" eye from nautilus' "pinhole" eye. We also showed that the type-2 co-option of transcription factors played important roles in the evolution of the lens and visual neurons. In summary, the cephalopod convergent morphological evolution of the camera eyes was driven by a mosaic of all types of gene recruitments. In addition, our analysis revealed unexpected variations of squids' opsins, retinochromes, and arrestins, providing more detailed information, valuable for further research on intra-ocular and extra-ocular photoreception of the cephalopods.

The gyri of the octopus vertical lobe have distinct neurochemical identities.

The cephalopod vertical lobe is the largest learning and memory structure known in invertebrate nervous systems. It is part of the visual learning circuit of the central brain, which also includes the superior frontal and subvertical lobes. Despite the well-established functional importance of this system, little is known about neuropil organization of these structures and there is to date no evidence that the five longitudinal gyri of the vertical lobe, perhaps the most distinctive morphological feature of the octopus brain, differ in their connections or molecular identities. We studied the histochemical organization of these structures in hatchling and adult Octopus bimaculoides brains with immunostaining for serotonin, octopus gonadotropin-releasing hormone (oGNRH), and octopressin-neurophysin (OP-NP). Our major finding is that the five lobules forming the vertical lobe gyri have distinct neurochemical signatures. This is most prominent in the hatchling brain, where the median and mediolateral lobules are enriched in OP-NP fibers, the lateral lobule is marked by oGNRH innervation, and serotonin immunostaining heavily labels the median and lateral lobules. A major source of input to the vertical lobe is the superior frontal lobe, which is dominated by a neuropil of interweaving fiber bundles. We have found that this neuropil also has an intrinsic neurochemical organization: it is partitioned into territories alternately enriched or impoverished in oGNRH-containing fascicles. Our findings establish that the constituent lobes of the octopus superior frontal-vertical system have an intricate internal anatomy, one likely to reflect the presence of functional subsystems within cephalopod learning circuitry.

A new antigenic marker specifically labels a subpopulation of the class II Kenyon cells in the brain of the European honeybee Apis mellifera.

The mushroom bodies are the higher-order integration center in the insect brain and are involved in higher brain functions such as learning and memory. In the social hymenopteran insects such as honeybees, the mushroom bodies are the prominent brain structures. The mushroom bodies are composed of lobed neuropils formed by thousands of parallel-projecting axons of intrinsic neurons, and the lobes are divided into parallel subdivisions. In the present paper, we report a new antigenic marker to label a single layer in the vertical lobes of the European honeybee Apis mellifera. In the brain of A. mellifera, a monoclonal antibody (mAb) 15C3, which was originally developed against an insect ecdysone receptor (EcR) protein, immunolabels a single layer of the vertical lobes that correspond to the most dorsal layer of the γ-lobe. The 15C3 mAb recognizes a single ~200 kDa protein expressed in the adult honeybee brain. In addition, the 15C3 mAb immunoreactivity was also observed in the lobes of the developing pupal mushroom bodies. Since γ-lobe is well known to their extensive reorganization that occurs during metamorphosis in Drosophila, the novel antigenic marker for the honeybee γ-lobe allows us to investigate morphological changes of the mushroom bodies during metamorphosis.

Two Pairs of Mushroom Body Efferent Neurons Are Required for Appetitive Long-Term Memory Retrieval in Drosophila

One of the challenges facing memory research is to combine network- and cellular-level descriptions of memory encoding. In this context, Drosophila offers the opportunity to decipher, down to single-cell resolution, memory-relevant circuits in connection with the mushroom bodies (MBs), prominent structures for olfactory learning and memory. Although the MB-afferent circuits involved in appetitive learning were recently described, the circuits underlying appetitive memory retrieval remain unknown. We identified two pairs of cholinergic neurons efferent from the MB α vertical lobes, named MB-V3, that are necessary for the retrieval of appetitive long-term memory (LTM). Furthermore, LTM retrieval was correlated to an enhanced response to the rewarded odor in these neurons. Strikingly, though, silencing the MB-V3 neurons did not affect short-term memory (STM) retrieval. This finding supports a scheme of parallel appetitive STM and LTM processing.

Principal component analysis of odor coding at the level of third‐order olfactory neurons in Drosophila

Olfactory information in Drosophila is conveyed by projection neurons from olfactory sensory neurons to Kenyon cells (KCs) in the mushroom body (MB). A subset of KCs responds to a given odor molecule, and the combination of these KCs represents a part of the neuronal olfactory code. KCs are also thought to function as coincidence detectors for memory formation, associating odor information with a coincident punishment or reward stimulus. Associative conditioning has been shown to modify KC output. This plasticity occurs in the vertical lobes of MBs containing α/α' branches of KCs, which is shown by measuring the average Ca(2+) levels in the branch of each lobe. We devised a method to quantitatively describe the population activity patterns recorded from axons of >1000 KCs at the α/α' branches using two-photon Ca(2+) imaging. Principal component analysis of the population activity patterns clearly differentiated the responses to distinct odors.

Distribution of glutamic acid decarboxylase immunoreactivity within the brain of oval squid Sepioteuthis lessoniana

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 19:97-109 (2013) - DOI: https://doi.org/10.3354/ab00525 FEATURE ARTICLEDistribution of glutamic acid decarboxylase immunoreactivity within the brain of oval squid Sepioteuthis lessoniana Shiori Kobayashi1, Chitoshi Takayama2, Yuzuru Ikeda1,* 1Department of Marine and Environmental Sciences, Graduate School of Engineering and Science, and 2Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa 903-0213, Japan *Corresponding author. Email: ikeda@sci.u-ryukyu.ac.jp ABSTRACT: Coleoid cephalopods (squid, cuttlefish, and octopus) have the largest and most complex brains of all invertebrates and show behavioral abilities similar to those of vertebrates. Among the coleoids, the oval squid Sepioteuthis lessoniana forms well-structured schools that are indicative of sociality. These behaviors are reflected in aspects of the well-developed brain. In this study, we focused on the role of the cephalopod brain in complex behavior. In order to reveal the network of γ-aminobutyric acid (GABA) in coleoids, we examined the immunohistochemical localization of glutamic acid decarboxylase (GAD), which is the synthetic enzyme of GABA, in the brain of young S. lessoniana. We found that GABAergic neurons and their axons were distributed throughout the brain. GABA neurons were abundantly localized in the inferior frontal lobe, which is involved in controlling arm motions, and in the subesophageal masses, which are lower and intermediate centers of action. GABAergic fibers were abundantly localized in the tract that runs from the superior frontal lobe to the vertical lobe. These results suggested the involvement of GABA in both cognitive behaviors (such as learning and memory) and in movement. KEY WORDS: Glutamic acid decarboxylase · Neurotransmitter · Brain · Oval squid · GABA · γ‑aminobutyric acid Full text in pdf format Information about this Feature Article NextCite this article as: Kobayashi S, Takayama C, Ikeda Y (2013) Distribution of glutamic acid decarboxylase immunoreactivity within the brain of oval squid Sepioteuthis lessoniana . Aquat Biol 19:97-109. https://doi.org/10.3354/ab00525 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 19, No. 2. Online publication date: September 24, 2013 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2013 Inter-Research.

3D beamforming: Performance improvement for cellular networks

The beam pattern of a mobile communication base station has significant impact on the performance of a cellular network. Three-dimensional (3D) beamforming combines the horizontal beam pattern adaptation, as applied for beamforming and multiple input multiple output (MIMO) schemes, with a vertical antenna pattern adaptation. The recent availability of new flexible antenna techniques enables a fully dynamic antenna pattern adaptation which can be specified per resource block and user equipment (UE), and makes 3D beamforming practically feasible. This paper describes the basic principles of 3D beamforming, including the impact of downtilt adaptation on the physical layer as well as the potential of its combination with beam coordination involving the media access control (MAC) layer. Our investigations assumed the vertical main lobe of the beam pattern was geometrically pointed towards the UE. We discuss a number of different realization options and simulation results including a Bell Labs field trial with vertical beam steering. Using wireless systems with state of the art Long Term Evolution (LTE) signal format and including the lightRadio™ antenna array, our trials in the Stuttgart testbed verified the basic predicted properties and potential advantages of 3D beamforming.