Basal forebrain nuclei

Fig. 2.20 Efferent pathways into bulb showing (a) cholinergic (ACh) fibres projecting to MOB from basal forebrain nuclei. AON = ant. olfactory nucleus, OT = olfactory tract, DB = diagonal band nuc. (from Davis et al., 1978). (b) Nor-Adrenalin input to AOB, via MFB pathway from brain stem centres (nuclei A1-2, A6) (from Keveme, 1971).

Momiyama T., Sim J. A. (1996). Modulation of inhibitory transmission by dopamine in rat basal forebrain nuclei activation of presynaptic Dl-like dopaminergic receptors. J. Neurosci. 16(23), 7505-12. 

Little is formally known about the toxicity of amanita use. Ibotenic acid is a potent neurotoxin, through excitatory amino acid mechanisms (Steiner et al. 1984 Schwarcz et al. 1984). It has been used extensively in animal research to create discrete neuroanatomical lesions. For example, it has been used to lesion the basal forebrain nuclei to create a putative animal model of Alzheimer s disease (Arbogast and Kozlowski 1988). 

Ishunina TA, van Beurden D, van der Meulen G, Unmehopa UA, Hoi EM, et al. 2005. Diminished aromatase immu-noreactivity in the hypothalamus, but not in the basal forebrain nuclei in Alzheimer s disease. Neurobiol Aging 26 173-194. 

Acetylcholine neuromodulatory system. The neurons that synthesize acetylcholine (molecular formula in box) are located in the pontine brainstem and basal forebrain. The brainstem nuclei (called Ch.5 and 6 in Mesulam s nomenclature) project locally and forward into the thalamus, subthalamus, basal forebrain, and limbic system. The basal forebrain nuclei (Ch.1-4) project to the cerebral cortex and limbic system. Compare with figure 2.1 to identify structures shown. In this and the following three drawings, the very extensive and complex projections to the cerebral cortex are not shown. 

The neural structures involved in the promotion of the waking (W) state are located in the (1) brainstem [dorsal raphe nucleus (DRN), median raphe nucleus (MRN), locus coeruleus (LC), laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT), and medial-pontine reticular formation (mPRF)] (2) hypothalamus [tuberomammillary nucleus (TMN) and lateral hypothalamus (LH)[ (3) basal forebrain (BFB) (medial septal area, nucleus basalis of Meynert) and (4) midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (Pace-Schott Hobson, 2002 Jones, 2003). The following neurotransmitters function to promote W (1) acetylcholine (ACh LDT/PPT, BFB) (2) noradrenaline (NA LC) (3) serotonin (5-HT DRN, MRN) (4) histamine (HA TMN) (5) glutamate (GLU mPRF, BFB, thalamus) (6) orexin (OX LH) and (7) dopamine (DA VTA, SNc) (Zoltoski et al, 1999 Monti, 2004). 

Basal forebrain accumbens nuclei, ventral palbdum, bed nucleus of the stria terminahs, diagonal band bed nucleus of the stria terminalis, diagonal band, ventral pallidum... 

Figure 12.1 Extracellular adenosine concentrations in different brain areas, measured with in vivo microdialysis from cats during sleep deprivation (6 h gentle handling) and recovery sleep. Concentrations are given as a percentage of pre-deprivation values. BF, basal forebrain CX, cingulate cortex TH, VA/VL nucleus of thalamus POA, preoptic hypothalamic area DRN, dorsal raphe nucleus PPT, pedunculopontine nucleus. In BF and CX adenosine rises during sleep deprivation, but starts to decline during deprivation in CX, whereas the decline occurs during recovery in the BF. In other areas there is no accumulation during sleep deprivation. Modified from Porkka-Heiskanen et al. (2000).

The rapid, low amplitude EEG activity of REM sleep, like that of waking, is sustained by cholinergic processes (Kinai Szerb, 1965 Phillis 8c Ghong, 1965), principally from neurons in the basal forebrain which project over the entire cortex (Divac, 1975 Lehmann et al., 1980 Bigl et al., 1982). Activation of the nucleus basalis of Meynert results in acetylcholine release in the cortex... 

Basal forebrain cholinergic nuclei project to all cerebral cortical areas and the amygdala (nbM), hippocampal formation, cingulate, and hypothalamus (medial septal nucleus and vertical limb of the diagonal band), and the olfac-... 

---