Antennal lobe is the deutocerebral
neuropilIn neuroanatomy, a neuropil, which is sometimes referred to as a neuropile, is a region between neuronal cell bodies in the gray matter of the brain and spinal cord . It consists of a dense tangle of axon terminals, dendrites and glial cell processes...
of the insect which receives the input from the olfactory sensory neurons on the
antennaAntennae in biology have historically been paired appendages used for sensing in arthropods and crustaceans. More recently, the term has also been applied to cilium structures present in many cell types of eukaryotes....
. Functionally, it shares some similarities with the
olfactory bulbThe olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
in vertebrates.
In insects, the olfactory pathway starts at the antennae (though in some insects like
DrosophilaDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
there are olfactory sensory neurons in other parts of the body) from where the sensory neurons carry the information about the
odorAn odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also called smells, which can refer to both pleasant and unpleasant odors...
ant molecules impinging on the antenna to the antennal lobe.
Antennal lobe is the deutocerebral
neuropilIn neuroanatomy, a neuropil, which is sometimes referred to as a neuropile, is a region between neuronal cell bodies in the gray matter of the brain and spinal cord . It consists of a dense tangle of axon terminals, dendrites and glial cell processes...
of the insect which receives the input from the olfactory sensory neurons on the
antennaAntennae in biology have historically been paired appendages used for sensing in arthropods and crustaceans. More recently, the term has also been applied to cilium structures present in many cell types of eukaryotes....
. Functionally, it shares some similarities with the
olfactory bulbThe olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
in vertebrates.
In insects, the olfactory pathway starts at the antennae (though in some insects like
DrosophilaDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
there are olfactory sensory neurons in other parts of the body) from where the sensory neurons carry the information about the
odorAn odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also called smells, which can refer to both pleasant and unpleasant odors...
ant molecules impinging on the antenna to the antennal lobe. The antennal lobe is composed of densely packed neuropils, termed
glomeruliThe glomerulus in olfaction is a structure in the olfactory bulb. It is made up of a globular tangle of axons from the olfactory receptor neurons in the olfactory epithelium and dendrites from the mitral cells, tufted cells, and other cell types.Glomeruli are important waystations in the pathway...
, where the sensory neurons synapse with the two other kinds of neurons, the projection neurons and the local neurons. There are 43 glomeruli in the Drosophila antennal lobe. The projection neurons project to higher brain centers such as the mushroom body and
lateral hornIn the thoracic region, the postero-lateral part of the anterior column projects lateralward as a triangular field, which is named the lateral column .-Nerve Cells in the Lateral Column:...
of the protocerebrum. The local neurons, which are primarily inhibitory, have their neurites restricted to the antennal lobe. In Drosophila, each olfactory sensory neuron generally expresses a single
olfactory receptorOlfactory receptors expressed in the cell membranes of olfactory receptor neurons are responsible for the detection of odor molecules. Activated olfactory receptors are the initial player in a signal transduction cascade which ultimately produces a nerve impulse which is transmitted to the brain...
gene, and the neurons expressing a given gene all transmit information to one or two spatially invariant glomeruli in the antennal lobe. Moreover, each projection neuron generally receives information from a single glomerulus. The interaction between the olfactory receptor neurons, local neurons and projection neurons reformats the information input from the sensory neurons into a spatio temporal code before it is sent to higher brain centers.
The plasticity and coding properties of the projection neurons are currently under intensive investigation at several laboratories.