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Basal Forebrain

Published: Jul 19, 2023
  /  
Updated: Jul 21, 2023

Written by Oseh Mathias

Founder, SpeechFit

The basal forebrain is a collection of structures located at the front and bottom of the brain, in the anterior part of the hypothalamus and bordering the inferior aspect of the anterior commissure. It's a critical component of the brain, involved in multiple functions, including sleep-wake regulation, learning, memory, and attention[1][2].

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Basal Forebrain. Newman et al. (2012)[3]

This region primarily consists of three major structures: the nucleus accumbens, the nucleus basalis of Meynert, and the medial septal nucleus. Additionally, the basal forebrain encompasses parts of the substantia innominata and the diagonal band of Broca. The precise anatomical boundaries of the basal forebrain are debated, but the general agreement revolves around these structures[4][5].

  • The nucleus accumbens is a central player in the reward circuit of the brain. It receives dopaminergic inputs from the ventral tegmental area and the substantia nigra and projects to regions like the prefrontal cortex and the hypothalamus[6].

  • The nucleus basalis of Meynert is primarily responsible for cholinergic projections to the cerebral cortex. These cholinergic neurons play crucial roles in the regulation of the sleep-wake cycle, attention, and memory. This nucleus's degeneration is implicated in cognitive decline seen in Alzheimer's disease, underscoring the importance of the cholinergic system in cognitive function[7][8].

  • The medial septal nucleus, with its cholinergic and GABAergic neurons, is linked bidirectionally with the hippocampus and is instrumental in generating theta waves, brain rhythms associated with various aspects of cognition, including learning and memory[9].

The cholinergic system of the basal forebrain, encompassing the nucleus basalis and medial septal nucleus among others, is of particular interest due to its extensive influence on cognition. Cholinergic neurons are the major source of acetylcholine in the brain, a neurotransmitter critically involved in memory and learning processes. They send widespread projections to the neocortex and limbic system, and modulate cortical arousal, influencing functions such as attention and sleep-wake cycles[10][11].

Author

Oseh Mathias

SpeechFit Founder

Oseh is passionate about improving health and wellbeing outcomes for neurodiverse people and healthcare providers alike.

References

  • M. Sarter, M.E. Hasselmo, J.P. Bruno, and B. Givens, "Unraveling the attentional functions of cortical cholinergic inputs: interactions between signal-driven and cognitive modulation of signal detection," Brain Research Reviews, vol. 48, no. 1, pp. 98-111, 2005.

  • G. Aston-Jones and J.D. Cohen, "An integrative theory of locus coeruleus-norepinephrine function: adaptive gain and optimal performance," Annual Review of Neuroscience, vol. 28, pp. 403-450, 2005.

  • Newman, E. L., Gupta, K., Climer, J. R., Monaghan, C. K., & Hasselmo, M. E. (2012). Major cholinergic projections of the central nervous system [Figure]. In Cholinergic modulation of cognitive processing: Insights drawn from computational models. Frontiers in Behavioral Neuroscience.

  • R. Hurley, L.M. Devilbiss, A. Waterhouse, "A matter of focus: Monoaminergic modulation of stimulus coding in mammalian sensory networks," Current Opinion in Neurobiology, vol. 14, no. 4, pp. 488-495, 2004.

  • J.P. Bruno, and M. Sarter, "Cortical cholinergic inputs mediating arousal, attentional processing and dreaming: differential afferent regulation of the basal forebrain by telencephalic and brainstem afferents," Neuroscience, vol. 95, no. 4, pp. 933-952, 2000.

  • R.A. Wise, "Role of brain dopamine in food reward and reinforcement," Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 361, no. 1471, pp. 1149-1158, 2006.

  • M.S. Albin, R.L. Bunegin, J.M. Duke, and A. Reilly, "Cholinergic mechanisms in the cerebral circulation," Anesthesia & Analgesia, vol. 57, no. 4, pp. 476-486, 1978.

  • T. Arendt, B. Bigl, V. Arendt, and A. Tennstedt, "Loss of neurons in the nucleus basalis of Meynert in Alzheimer's disease, paralysis agitans and Korsakoff's Disease," Acta Neuropathologica, vol. 61, no. 2, pp. 101-108, 1983.

  • A. Vinogradova, "Hippocampus as comparator: role of the two input and two output systems of the hippocampus in selection and registration of information," Hippocampus, vol. 11, no. 5, pp. 578-598, 2001.

  • E.K. Perry, B.E. Tomlinson, G. Blessed, K. Bergmann, P.H. Gibson, and R.H. Perry, "Correlation of cholinergic abnormalities with senile plaques and mental test scores in senile dementia," British Medical Journal, vol. 2, no. 6150, pp. 1457-1459, 1978.

  • M. Mesulam, E.J. Mufson, A.I. Levey, and B.H. Wainer, "Cholinergic innervation of cortex by the basal forebrain: cytochemistry and cortical connections of the septal area, diagonal band nuclei, nucleus basalis (substantia innominata), and hypothalamus in the rhesus monkey," Journal of Comparative Neurology, vol. 214, no. 2, pp. 170-197, 1983.