Septal area

Anatomical terms of neuroanatomy

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The septal area (medial olfactory area) is an area in the lower, posterior part of the medial surface of the frontal lobe, and refers to the nearby septum pellucidum.

The septal nuclei are located in this area. The septal nuclei are composed of medium-size neurons which are classified into dorsal, ventral, medial, and caudal groups.[1] The septal nuclei receive reciprocal connections from the olfactory bulb, hippocampus, amygdala, hypothalamus, midbrain, habenula, cingulate gyrus, and thalamus. The septal nuclei are essential in generating the theta rhythm of the hippocampus.

The septal area (medial olfactory area) has no relation to the sense of smell, but it is considered a pleasure zone in animals. The septal nuclei play a role in reward and reinforcement along with the nucleus accumbens(因為lateral septal area投射到VTA). In the 1950s, Olds & Milner showed that rats with electrodes implanted in this area will self-stimulate repeatedly (i.e., press a bar to receive electrical current that stimulate the neurons).[2]Experiments on the septal area of humans have taken place since the 1960s.[3][4][5][6]

Contents

?1Connections

?1.1Lateral septum and social behavior

?2References

?3External links

Connections[edit]

Detail of drawing showing components of septal area below corpus callosum.

The septal area is located on the lower posterior part of the frontal lobe. The septal area refers to the nearby septum pellucidum. It is located underneath the corpus callosum and in front of the lamina terminalis. The lamina terminalis is a layer of gray matter that connects the optic chiasma and the anterior commissure.[7] The septal nuclei are in the septal area, and are essential in generating the theta rhythm of the hippocampus.[8]

The dorsal septum projects to the lateral preoptic area, lateral hypothalamus, periventricular hypothalamus and midline thalamus

（dorsal septum投射到midline thalamus，這意味著dorsal septum涉及對疼痛的調(diào)節(jié)；投射到lateral preoptic area，意味著dorsal septum涉及對睡眠的調(diào)節(jié)；投射到lateral hypothalamus，意味著dorsal septum涉及對飲食的調(diào)節(jié)。）.

Fibers from the ventral half of the septum project topographically to the hippocampal formation, thalamus, hypothalamus and midbrain

（這里不應該是medial septal nucleus嗎？難道ventral half of the septum是diagonal band of Broca？這個猜想倒是和本段后面的內(nèi)容達成一致。）

. Specifically, neurons located along the midline in the vertical limb of the diagonal band of Broca project through the dorsal fornix to all CA fields of the dorsal hippocampus and adjacent subicular cortex. Other fibers from this region project through the stria medullaris to the medial and lateral habenular nuclei, the paratenial and anteromedial nucleus of the thalamus

(這句話對medial and lateral habenular nuclei的描述不清晰，基本等于無用；而paratenial and anteromedial nucleus of the thalamus也是涉及疼痛。這一段內(nèi)容好像是在描述diagonal band of Broca，難道ventral half of the septum是diagonal band of Broca？)

, and through the medial forebrain bundle to the pars posterior of the medial mammillary nucleus.

Cells located in the intermediolateral septum also project through the lateral part of the fimbria to all CA fields of the ventral hippocampus and adjacent subicular and entorhinal cortices（這里好像說的是medial septal nucleus。但是為什么不用通用的說法呢？）. These cells also send fibers through the stria medullaris to the lateral habenular nucleus and mediodorsal thalamic nucleus. Other axons arising from these cells descend through the medial forebrain bundle to terminate in a region dorsal to the interpeduncular nucleus.

The lateral septum is a relay center for connections from the CA3 of the hippocampus to the ventral tegmental area.

（本詞條中所有內(nèi)容，只有這句話是描述最明確的，最有用的，說明只有CA3的活動是可以通過lateral septum興奮VTA。）?

These connections help link reward signals with the context in which they occur.[9]

Fibers from the most lateral part of the ventral septum (i.e., bed nucleus of the anterior commissure) project through the stria terminalis to the ventral subiculum. In addition, cells located in the horizontal limb of the diagonal band project massively to the pars posterior of the medial mammillary nucleus, the ventral tegmental area, and amygdala.

Lateral septum and social behavior[edit]

Inhibitory GABA, and excitatory glutamate, which regulate lateral septum (LS) activity, have been found to be increased during social play in juvenile rats. No sex differences were found in extracellular GABA concentrations during social playing, however, glutamate plays a major role in female social playing. When glutamate receptors are blocked in the LS pharmacologically, there is a significant decrease in female social playing, while males had no decrease in playing. This suggests that in the lateral septum, GABA neurotransmission is involved in social play behavior regulation in both sexes, while glutamate neurotransmission is sex-specific, involved in regulation of social play only in female juvenile rats.[10]

總的來說，這是一個描述不清，以及一定程度混亂的詞條，估計是現(xiàn)有的研究成果遠沒有弄清楚其功能吧，但是為什么詞條中連起碼的連接結(jié)構(gòu)都描述得如此模糊，這解剖學上的知識不應該是科研難點啊。所以，septal area的連接結(jié)構(gòu)和功能還不清楚，有待我去進一步確定。雖然常規(guī)的科學手段難以確定其功能，但是我有很多線索去研究septal area，比如它投射到海馬區(qū)域，那么就可以通過海馬區(qū)域活動時對應的行為去研究，還比如它投射到interpeduncular nucleus和habenular nucleus，那么就可以用對應的行為特征去研究。