I completed undergraduate work at the University of California, Berkeley in 1972, and obtained my Ph.D. from Harvard University in 1977. My thesis was on extracellular electrophysiology in the rat hippocampal slice and included some of the early studies on LTP. My postdoctoral training was with Roger Nicoll at UCSF. In 1981 I became an Assistant Professor in Department of Physiology at UMAB and in 1992 was promoted to Professor with tenure. Work in my lab is supported by NIH funding.
My colleagues and I study the neurophysiological basis of epilepsy and of learning and memory in the mammalian brain. These disparate phenomena have common features: They have prominent electrophysiological manifestations in the hippocampus, they can be modeled in an in vitro brain slice preparation, and their occurrence depends on the state of neuronal excitability in the tissue. We use state-of-the-art electrophysiological techniques (intracellular, whole-cell, patch-clamp, field potential) in the hippocampal slice to investigate an aspect of excitability control that is crucial for the establishment of memory traces and for the prevention of epileptic seizures: the strength of synaptic inhibition mediated by the neurotransmitter, GABA. Decreases in GABA inhibition facilitate the induction of long-term potentiation (LTP), an increase in synaptic excitation that is the primary candidate for the neurophysiological basis of learning and memory.
Decreases in GABA inhibition also promote the onset of the epileptic seizure, a state of hyperexcitability characteristic of epilepsy. How does the nervous system maintain the fine distinction necessary to encourage the former while preventing the latter? What cellular controls on inhibition are normally present in the brain and how are these controls altered in physiological and pathophysiological ways? These are the sorts of questions we try to answer. We discovered a new mode of cellular communication that may solve part of the puzzle: the target (pyramidal) cells, the ones towards which inhibition is directed, may regulate their own state of inhibition by sending a signal backwards across the synaptic junctions (retrograde signaling) and thereby causing the inhibitory interneurons to stop releasing GABA temporarily.
Many laboratories have begun studying this phenomenon, and the most interesting and surprising thing is that the signal from the pyramidal cell to the interneuron is a molecule that has been called "the brain's own marijuana". In the mammalian brain are specialized receptors that recognize and bind to the active ingredient in marijuana, THC. The natural compound that is active at these receptors is not THC, of course, but an "endocannabinoid", a molecule recently recognized as capable of carrying signals between brain cells. How do these molecules normally work? What can they teach us about the mechanisms of drug abuse and potential medical use of marijuana and other cannabinoids? We will use a variety of experimental approaches to resolve these interesting problems.
Lab Techniques and Equipment
Preparations: acute in vitro hippocampal slices; tissue cultured hippocampal slices and cells.
Electrophysiological techniques: intracellular and extracellular recordings; whole-cell voltage- and current clamp; intradendritic, single channel and perforated patch recordings.
Imaging techniques: intracellular calcium-imaging, and confocal and two-photon microscopy to study labeled cells in slices; infra-red, differential interference contrast visualization of cells in living slices.
Aihui Tang, Ph.D.
Kun Yang, Ph.D.
Daniel Nagode, B.S.
Wang M, Hill MH, Zhang L, Gorzalka B, Hillard CJ, Alger BE (2012) Acute restraint stress enhances hippocampal endocannabinoid function via glucocorticoid receptor activation. J Psychopharmacol (Sep 2011, ePUB on-line) 26:56-71. PMCID: PMC3373303
Nagode, DA, Tang AH, Karson, MA, Klugmann, M, Alger BE (2011) Optogenetic release of ACh induces rhythmic bursts of perisomatic IPSCs in hippocampus. PLoS ONE 6:e27691. PMCID: PMC3218010
Alger BE, Kim J (2011) Supply and demand for endocannabinoids. Trends Neurosci 34:304-15. PMCID: PMC3106144
Tang AH, Karson MA, Nagode DA, McIntosh JM, Uebele VN, Renger JJ, Klugmann M, Milner TA, Alger BE (2011) Nerve terminal nAChRs initiate quantal GABA release from perisomatic interneurons by activating axonal T-type (Cav3) Ca2+ channels and Ca2+ release from stores. J Neurosci 31:13546-13561. PMCID: PMC3353409
Waddell J, Kim J, Alger BE, McCarthy MM (2011) The Depolarizing Action of GABA in Cultured Hippocampal Neurons Is Not Due to the Absence of Ketone Bodies. PLoS ONE 6(8):e23020. PMCID: PMC3158756
Zhang L, Wang M, Bisogno T, Di Marzo V, Alger BE (2011) Endocannabinoids generated by Ca2+ or by metabotropic glutamate receptors appear to arise from different pools of diacylglycerol lipase. PLoS ONE Jan 28; 6(1):e16305. PMCID: PMC3030617
Zhang L and Alger BE (2010) Enhanced endocannabinoid signaling elevates neuronal excitability in fragile X syndrome. J Neurosci 30:5724-5729. PMCID: PMC2906112
Kim J and Alger BE (2010) Reduction in endocannabinoid tone is a homeostatic mechanism for specific inhibitory synapses. Nature Neurosci 13:592-600. PMCID: PMC2860695
Karson MA, Tang AH, Milner TA, Alger BE (2009) Synaptic cross talk between perisomatic-targeting interneuron classes expressing cholecystokinin and parvalbumin in hippocampus. J Neurosci 29:4140-54. PMCID: PMC2853357
Lafourcade CA, Alger BE (2008) Distinctions among GABAA and GABAB responses revealed by calcium channel antagonists, cannabinoids, opioids and synaptic plasticity in rat hippocampus. Psychopharmacol, (Dec 2007; ePUB on-line) 198:539-549. PMCID: PMC2906116
Edwards DA, Zhang L, Alger BE (2008) Metaplastic control of hippocampal endocannabinoid responses. Proc Natl Acad Sci (USA), 105:8142-8147. PMCID: PMC2409138
Reich CG, Mohammadi M, Alger BE (2008) Endocannabinoid modulation of responses in multiple-trial trace and delay fear conditioning. J Psychopharmacol (Feb 2008; ePUB on-line) 22:769-77. PMCID: PMC2906780
Karson MA, Whittington KC, Alger BE (2008) Cholecystokinin inhibits endocannabinoid-sensitive hippocampal IPSPs and stimulates others. Neuropharmacol (July 2007; ePUB on-line) 54:117-128. PMCID: PMC2242378
Edwards, D.A., Kim, J. and Alger, B.E. (2006) Multiple mechanisms of endocannabinoid response initiation in hippocampus. J. Neurophysiol. (ePUB online October 5, 2005) 95: 67-75.
Isokawa, M. and Alger, B.E. (2006) The ryanodine receptor regulates endogenous cannabinoid mobilization in the hippocampus. J. Neurophysiol. (ePUB online February 5, 2006) 95: 3001-3011.
Reich, C.G., Karson, M.A., Karnup, S.V., Jones, L.M. and Alger, B.E. (2005) Regulation of IPSP theta rhythm by muscarinic receptors and endocannabinoids in hippocampus. J. Neurophysiol. 94: 4290-4299.
Isokawa, M. and Alger, B.E. (2005) Retrograde endocannabinoid regulation of GABAergic inhibition in the rat dentate gyrus granule cell. J. Physiol. 567: 1001-1010.
Heinbockel, T., Brager, D.H., Reich, C.G., Zhao, J., Muralidharan, S., Alger, B.E. and Kao, J.P. (2005) Endocannabinoid signaling dynamics probed with optical tools. J. Neurosci. 25(41): 9449-9459.
Kim, J., and Alger, B.E. (2004) Inhibition of cyclooxygenase-2 potentiates retrograde endocannabinoid signaling in hippocampus. Nature Neurosci. 7: 697-699.
Brager, D.H., Luther, P.W., Edrélyi, F., Szabó, G. and Alger, B.E. (2003) Regulation of exocytosis from single visualized GABAergic boutons in hippocampal slices. J. Neurosci. 23(33): 10475-10486.
Reich, C.G., Mason, S.E. and Alger, B.E. (2003) A novel form of LTD induced by transient, partial inhibition of the Na,K-pump in rat hippocampal CA1 cells. J. Neurophysiol. 91: 239-247.
Vaillend, C., Mason, S.E., Cuttle, M.F. and Alger, B.E. (2002) Mechanisms of neuronal hyperexcitability caused by partial inhibition of Na+, K+ -ATPases in the rat CA1 hippocampal region. J. Neurophysiol. 88: 2963-2978
Alger, B.E. (2002) Retrograde signaling in the regulation of synaptic transmission: focus on endocannabinoids. Progress in Neurobiology. 68: 247–286
Kim, J., Isokawa, M., Ledent, C. and Alger, B.E. (2002) Activation of muscarinic acetylcholine receptors enhances the release of endocannabinoids in the hippocampus. J. Neurosci. 22: 10182-91
Varma, N., Brager, D.H., Morishita, W., Lenz, R.A.,
Carlson, G., Wang, Y. and Alger, B.E. (2002) Endocannabinoids facilitate the induction of LTP in the hippocampus. Nature Neurosci. 5: 723-724.