Anterior commissure

Figure 12.3 Sections of rat brain at 0.2 mm anterior to bregma (B + 0.2), and 0.3 and 0.8 mm posterior (B - 0.3, B - 0.8), showing areas relevant to adenosine influences on sleep induction. HDB, horizontal diagonal band MCPO, magnocellular preoptic nucleus VLPO, ventrolateral preoptic nucleus ac, anterior commissure ox, optic chiasm.

Bennett, M. H. (1968). The role of the anterior limb of the anterior commissure in olfaction. Physiology and Behavior 3,507-515. 

Figure 1. Frontal section through human brain stained for acetylcholinesterase (frame A) and diagram showing locations of individual cholinergic cells irregularly dispersed throughout the nucleus basalis of Meynert and surrounding regions of human brain (frame B). Abbreviations AC, anterior commissure B, nucleus basalis of Meynert gpe, globus pallidus external part gpi, globus pallidus internal part, 1C internal capsule P, putamen.

LaMantia, A.-S., and Rakic, P. (1994) Axon overproduction and elimination in the anterior commissure of the developing rhesus monkey. / Comp Neurol 340 328-336. 

Fig. 50 A schematic map of a horizontal frontal lobe section showing the location where double-labeling for /3111-tubulin and BrdU in postischemic day-23 monkey RMS was investigated. Pu, putamen ac, anterior commissure. This statistical analysis of the density of BrdU+ cells in RMS involves postischemic day 23. p < 0.05 versus control paired t test...

In the rat, the motor striatum comprises the lateral portion of the CPu and receives input from the motor cortex (lateral and medial agranular cortical fields). This region of the striatum is equivalent in primates to the dorsolateral portion of the caudate nucleus and the dorsolateral putamen caudal to the anterior commissure, which receives input from the primary motor, premotor and supplementary motor areas. 

The associative striatum comprises instead in the rat the medial portion of the CPu, which receives input from the anterior cingulate area (considered analogous to the dorsolateral prefrontal cortex in primates). In primates the associative striatum includes most of the head, body and tail of the caudate and large parts of the putamen rostral to the anterior commissure it receives input from associative areas of the cortex, including those of the prefrontal cortex. 

The ventral striatum (NAc and olfactory tubercle) send efferents to the ventral pallidum, which represents a ventral extension of the GP lying below the anterior commissure in the forebrain. The ventral pallidum also receives a dopaminergic innervation from the VTA (Beckstead et al., 1979), and noradrenergic innervation from the locus coeruleus. 

IPA interpeduncular nucleus, apical subnucleus 46-48, 79, 95-96 IPAC interstitial nucleus of the posterior limb of the anterior commissure 16-17, 25-31, 83-84, 86-87, 96-100 IPACL interstitial nucleus of the posterior limb of the anterior commissure, lateral part 18-24... 

IPACM interstitial nucleus of the posterior limb of the anterior commissure, medial part 18-24... 

TABLE 2 Coordinates of the bed nucleus of the anterior commissure and the trochlear nucleus obtained from the three planes... 

BAC bed nucleus of the anterior commissure 21, 81,102-103 BAOT bed nucleus of the accessory olfactory tract 26-29, 84,90-91 Bar Barrington s nucleus 56-60,99-100 bas basilar artery 45-66, 79... 

Architecture of the MOB (A, B) and primary olfactory cortex (POC, C). A and B Coronal section (Nissl stain) of the rat MOB at low (A) and high (B) magnifications. C Coronal section through the rat brain showing several structures of the POC. Abbreviations ac, anterior commissure Acb, nucleus accumbens AONvp, anterior olfactory nucleus, ventroposterior division DP, dorsal peduncular cortex IL, infralimbic cortex Pir, piriform cortex SEL, subependymal layer Scale bar in A and C = 1 mm. Modified from Handbook of Chem. Neuroanat. Integrated Sys. CNS, Vol. 12, Part III, Chapter III, The Olfactory System, M. Shipley etal., pp. 469-573,1996, with permission from Elsevier... 

Cholinergic Actions in MOB Only limited information is available about cholinergic actions in MOB. Electrical activation of NDB has been reported to depress (Nickell and Shipley, 1988a) or increase (Kunze et al., 1991, 1992) mitral cell activity indirectly via primary effects on GABAergic GCs. NDB stimulation also reduced the field potential in the MOB caused by stimulation of the anterior commissure (Nickell and Shipley, 1993), an effect mediated by presynaptic inhibition of anterior commissure terminals via muscarinic receptors. One interpretation of these results is that cholinergic input to MOB may function to modulate interhemispheric transmission of olfactory information. In this regard, it is noteworthy that anterior commissural fibers are required for access and recall of olfactory memories between the two hemispheres. Infusion of ACh into MOB was reported to reduce paired-pulse depression of lateral olfactory tract (LOT)-evoked field potentials recorded in the GCL. This effect was attributed to... 

Mori K, Takagi SF. 1978. Activation and inhibition of olfactory bulb neurones by anterior commissure volleys in the rabbit. J Physiol (Lond) 279 589-604. 

Abbreviations Al = primary auditory area ac = anterior commissure Acc = accumbens nucleus AON = anterior olfactory nucleus BF = barrel field BLA = basolateral nucleus of the amygdala CAl = cornu ammonis 1 CA3 = cornu ammonis 3 cc = corpus callosum Cg = cingulate area CPu = caudate-putamen DCb = deep cerebellar nuclei DCo = dorsal cochlear nucleus DG = dentate gyrus DMV = dorsal motor nucleus of the vagus nerve ECu = external cuneate nucleus EP = external plexiform layer ER = entorhinal cortex f = fornix Fa = facial nucleus fa = facial nerve fr = fasciculus retroflexus G1 = glomerular layer GPe = (external segment of the)... 

Fig. 1 Oxytocin effects on amygdala activation. (A) Rendering on normal coronal MRl at the level of the anterior commissure (in neurological orientation brain left is on viewer s left). Response to face stimuli left, scene stimuh right. Top placebo, bottom oxytocin. See Table 2 for statistical information. (B) Significantly higher activation under placebo than oxytocin (main effect of drug condition). (C) Plot of bold in amygdala region of interest. From Kirsch et al. 2005, with permission...

The striatum comprises the caudate, putamen and nucleus accumbens. In mammals in which corticofugal fibers coalesce into the internal capsule within the striatum, the caudate nucleus and putamen nucleus are separated by this partition. In animals in which corticofugal fibers are dispersed there is no clear separation between these nuclei, thus the term caudate-putamen is often used. The caudate and putamen, in most species, generally occupy the dorsal part of the striatum. The nucleus accumbens is the rostro-ventral extension of the striatum, and occupies the area surrounding the anterior commissure in the rostral part of the striatum. The term ventral striatum is generally used to refer to the nucleus accumbens and more caudally, the ventral most part of the striatum (Fleimer and Wilson 1975). The olfactory tubercle is sometimes included as a part of the ventral striatum, but in this review will not be discussed. 

Fig. 13. Basic olfactory network. Schematic of the networks linking the olfactory bulb and primary olfactory cortex. Olfactory nerve axons (ON) terminate in the glomeruli (glom) onto mitral (m) and tufted (t) cells which project via the lateral olfactory tract (LOT) to layer la of primary olfactory cortex to terminate on the dendrites of layer Il-III pyramidal (p) cells. Layer 11-111 pyramidal cells in rostral olfactory cortex project to layer Ib in caudal olfactory cortex and vice versa. Olfactory cortical pyramidal cells also send reciprocal projections back to the olfactory bulb. Thus olfactory bulb output is continuously modified by feedback from areas it targets. Inhibitory interneurons in olfactory bulb and olfactory cortex (shown in gray) modulate network function. Neurons in the ipsilateral (AONi) and contralateral anterior olfactory nuclei (AON) link olfactory networks in the two hemispheres via the anterior commissure.

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