Ataxia; Chorea; Dystonia; Tourette Syndrome; Motor Skills; Movement Disorders; Neurology; Pediatrics; Tremor; Parkinsonian Disorders
The striatum is a cluster of cells within the brain that helps execute normal movements and establishes goal directed behaviors. The symptoms of Parkinsonism and other debilitating neuropsychiatric disorders in children are caused by abnormal dopamine and acetylcholine availability in the striatum. Dr. Bamford’s laboratory investigations show how dopamine can trigger lasting changes in acetylcholine and will generate new pharmacological targets and treatments for parkinsonism and the dyskinetic motor movements that accompany treatment.
Extensive Research Description
Dr. Bamford has a strong track record of research funding, ranging from private grants to NIH. Dr. Bamford’s laboratory investigations focus on the function of the mammalian corticostriatal system. This system includes a collection of neurons that connect the cerebral cortex and striatum. The striatum plays an essential role in cognition, motor control, cue-dependent behaviors and abnormal function underlies aspects of numerous developmental, neurological, and psychiatric disorders, including Tourette syndrome, attention deficit–hyperactivity disorder, substance abuse, Parkinson’s disease, and Huntington’s disease. New treatments are needed and Bamford’s investigations offer critical insights into novel treatment options. In these disorders, too much or too little dopamine alters striatal excitation, resulting in clinical symptoms. To gain insight into synaptic plasticity induced by alterations in dopamine availability, the Bamford Lab combines behavioral investigations with optical, electrophysiological, biochemical, and immunohistochemical methods to determine the mechanisms underlying striatal modulation of glutamate release by dopamine, GABA, endocannabinoids, adenosine, and acetylcholine.
Since establishing his laboratory at the University of Washington in 2002, Dr. Bamford has published exceptional papers in Neuron, the Journal of Neuroscience, the Journal of Physiology, Annals of Neurology, and Nature Neuroscience. His work utilizes a novel technique, developed by Bamford and David Sulzer at Columbia University, which allows direct optical visualization of presynaptic cortical terminals in the striatum. This technique provides a robust way to measure kinetics of glutamate release from individual synaptic terminals. Investigations demonstrate that glutamate release from cortical projections in the motor striatum is directly regulated by dopamine, adenosine, and endocannabinoids. By regulating a subset of terminals, dopamine and these other neuromodulators alter the parallel processing of cortical inputs to the striatum, affecting striatal filtering of cortical information that leads to specific behaviors in mice (Neuron, 2004). Using dopamine-deficient mice and dopamine depleted mice, Bamford demonstrated that dopamine is not required during development for functional dopamine receptors. Dopamine depletion results in hypersensitive dopamine receptors that result in aberrant striatal function resulting in motor dyskinesias (Journal of Neuroscience, 2004).
Dopamine excess, as modeled by repeated use of the psychostimulants amphetamine and methamphetamine, produces a chronic striatal depression that is renormalized by drug reinstatement. This effect is dose dependent, long lasting (>140 days) and is dependent on a new D1 receptor effect seen only in animals with previous psychostimulant experience.During withdrawal, a psychostimulant challenge produces a paradoxical increase in glutamate release. This increase in glutamate from suppressed terminals correlates with locomotor sensitization and the model extends to drug intake escalation, both hallmarks of addiction (Neuron, 2008). These findings received wide press coverage and included reports on BBC National and World Radio, ABC, Washington Post, Science and Nature, New Scientist, and Scientific American.
In other studies, Bamford and co-workers found that the huntingtin mutation produces age-dependent alterations in corticostriatal activity that is paralleled by a decrease in dopamine D2 receptor modulation of the presynaptic terminal. Taken together, these findings point to dynamic alterations in the corticostriatal pathway and emphasize that therapies directed toward alleviating or preventing symptoms need to be specifically designed depending on the progression of the disorder (Journal of Neuroscience, 2008).
More recently, the Bamford lab showed how dopamine, endocannabinoids, and adenosine modulate frontal cortical projections to the nucleus accumbens (Journal of Physiology, 2012). In this study, workers combined optical recordings of presynaptic release with whole-cell electrophysiology in CB1 receptor-null mice and bacterial artificial chromosome (BAC) transgenic mice
Bamford also published a important article describing the behavioral effects of prenatal cocaine exposure (PCE) and the synaptic and biochemical mechanisms that might account for those behaviors (Annals of Neurology, 2013). PCE remains a serious health problem and can produce significant developmental and motor disabilities in affected humans. Observations in the clinic and laboratory strongly suggest that PCE causes corticostriatal dysfunction, but this important pathway has never been investigated. In this manuscript, Bamford and co-workers used a murine model for PCE to characterize abnormal dopamine-dependent behaviors and synaptic plasticity of the corticostriatal pathway. They found that PCE reduces body growth and modifies dopamine-dependent motor behaviors in adolescent mice. Abnormal motor-learning and blunted locomotor responses to repeated amphetamine were paralleled by a reversible GABA-dependent over-inhibition at corticostriatal synapses and a reduction in phasic dopamine release capacity. The release of dopamine promoted normal corticostriatal filtering in controls, but alleviated GABA-mediated inhibition and paradoxically increased corticostriatal activity in those mice with a history of PCE. While GABAA receptors had no effect on presynaptic corticostriatal activity in controls, their inhibition normalized synaptic function following PCE and prevented D2 receptor-dependent paradoxical presynaptic potentiation suggesting new therapeutic approaches for behaviors that follow PCE.
The Bamford laboratory has collaborated extensively with the Palmiter laboratory at the University of Washington on a number of projects. We showed that amphetamine sensitization requires balanced NMDA receptor activity in dopamine D1 and D2 receptor-expressing medium spiny neurons (PNAS, 2011) and that attenuating GABAA receptor signaling in dopamine neurons selectively enhances reward learning and alters risk preference in mice (Journal of Neuroscience, 2011). In another paper published in Nature Neuroscience (2012), we showed that the orphan G-protein-coupled receptor GPR88 is robustly expressed in medium spiny neurons in the striatum and regulated by neuro-pharmacological drugs. In the absence of GPR88, medium spiny neurons have increased glutamatergic excitation and reduced GABAergic inhibition that together promote enhanced firing rates in vivo, resulting in hyperactivity, poor motor-coordination, and impaired cue-based learning in mice. Targeted viral expression of GPR88 in medium spiny neurons rescues the molecular and electrophysiological properties and normalizes behavior, suggesting that aberrant medium spiny neurons activation in the absence of GPR88 underlies behavioral deficits and its dysfunction may contribute to behaviors observed in neuropsychiatric disease.
Dr. Bamford’s study published in the Journal of Neuroscience (2013) shows how acetylcholine encodes long-lasting presynaptic plasticity at glutamatergic synapses in the dorsal striatum after repeated amphetamine. Locomotion and cue-dependent behaviors are modified through corticostriatal signaling, where short-term increases in dopamine availability can provoke persistent changes in glutamate release that contribute to neuropsychiatric disorders including Parkinson’s disease and drug dependence. He showed that withdrawal of mice from repeated amphetamine treatment caused a chronic presynaptic depression (CPD) in glutamate release that was most pronounced in corticostriatal terminals with a low probability of release and lasted more than 50 days in treated mice. An amphetamine challenge reversed CPD, via a dopamine D1-receptor-dependent paradoxical presynaptic potentiation (PPP) that increased corticostriatal activity in direct pathway medium spiny neurons. This PPP correlated with locomotor responses following a drug challenge, suggesting that it may underlie the sensitization process. Experiments in slices and in vivo indicated that dopamine regulation of acetylcholine release from tonically active interneurons (TANs) contributes to CPD, PPP, locomotor sensitization, and cognitive ability. Thus, a chronic decrease in corticostriatal activity during withdrawal is regulated around a new physiological range by TANs and returns to normal upon re-exposure to amphetamine, suggesting that this paradoxical return of striatal activity to a more stable, normalized state may represent an additional source of drug motivation during abstinence.
The Bamford laboratory is currently supported by the NIH: Dopamine-Induced Striatal Synaptic Plasticity (2R01NS060803-07).
Varicella-Zoster Virus Retrobulbar Optic Neuritis in a Patient with Human Immunodeficiency Virus
Shayegani A*, Odel JG, Kazim M, Hall LS, Bamford N, Schubert H. American Journal of Ophthalmology. 122(4):586-588.
Congenital Guillain-Barré syndrome associated with maternal inflammatory bowel disease is responsive to intravenous immunoglobulin
Bamford NS*, Trojaborg W, De Vivo DC. European Journal of Paediatric Neurology. 6(2):115-119.
Heterosynaptic dopamine neurotransmission selects sets of corticostriatal terminals
Bamford NS, Zhang H, Schmitz Y, Wu N-P, Cepeda C, Levine MS, Schmauss C, Zakharenko SS, Zablow L, Sulzer S*. Neuron. 42:653-663.
Dopamine modulates release from corticostriatal terminals
Bamford NS*, Robinson S, Palmiter RD, Joyce JA, Moore C, Meshul CK. Journal of Neuroscience. 24:9541-9552
Repeated exposure to methamphetamine causes long-lasting presynaptic corticostriatal depression that is renormalized with drug readministration
Bamford NS*, Zhang H, Joyce JA, Scarlis CA, Hanan W, Wu N-P, André VM, Cohen R, Cepeda C, Levine MS, Harleton E, Sulzer D. Neuron. 58 (1): 89-103
Neuromuscular Hip Dysplasia in Charcot Marie Tooth Disease Type 1A
Bamford NS*, White KK, Robinett SA, Otto RK, Gospe SM. Developmental Medicine and Child Neurology. 51(5):408-11
Age-dependent alterations of corticostriatal activity in the YAC128 mouse model of Huntington Disease
Joshi PR, Wu N-P, André VM, Cummings D, Cepeda C, Joyce JA, Carroll JB, Leavitt BR, Hayden MR, Levine MS, Bamford NS*. Journal of Neuroscience. 29(8):2414-2427
Balanced NMDA receptor activity in dopamine D1 receptor (D1R)- and D2R-expressing medium spiny neurons is required for amphetamine sensitization
Beutler LR, Wanat MJ, Quintana A, Sanz E, Bamford NS, Zweifel LS, Palmiter RD*. PNAS. 108(10):4206-11
Attenuating GABAA Receptor Signaling in Dopamine Neurons Selectively Enhances Reward Learning and Alters Risk Preference in Mice
Parker JG, Wanat MJ, Soden ME, Ahmad K, Zweifel LS, Bamford NS, Palmiter RD* Journal of Neuroscience. 31(47):17103-12
Imaging Presynaptic Exocytosis in Corticostriatal Slices
Yue M, Sulzer D, Bamford NS*. Methods Molecular Biology. 793, 363-376
Lack of Gpr88 Regulates Medium spiny Neuron Activity and Facilitates Motor and Cue-dependent behaviors
Quintana A, Sanz E, Wang W, Storey GP, Guler AD, Wanat MJ, Roller BA, La Torre A, McKnight GS, Bamford NS, Palmiter RD*. Nature Neuroscience. 15(11)1547-55
Regulation of Prefrontal Excitatory Neurotransmission by Dopamine in the Nucleus Accumbens Core
Wang W, Dever D, Lowe J, Storey GP, Bhansali A, Eck EK, Nitulescu I, Weimer J, Bamford NS*. Journal of Physiology. 590(16)3743-60
Over-inhibition of Corticostriatal Activity following Prenatal Cocaine Exposure
Wang W, Nitulescu I, Lemos JC, Lewis JS, Bamford IJ, Posielski NM, Storey GP, Phillips PEM, Bamford NS*. Annals of Neurology. 73(3):355-69
Acetylcholine Encodes Long-lasting Presynaptic Plasticity at Glutamatergic Synapses in the Dorsal Striatum after Repeated Amphetamine Exposure
Wang W, Darvas M, Storey GP, Bamford IJ, Palmiter RD, Bamford NS*. Journal of Neuroscience. 33(25)10405-26
Dopamine-dependent corticostriatal synaptic filtering regulates sensorimotor behavior
Wong MY, Borgkvist A, Choi, SJ, Mosharov EV, Bamford NS, Sulzer D*. Neuroscience. 290. 594-607
Nicotine Modifies Corticostriatal Plasticity and Amphetamine Rewarding Behaviors in Mice(1,2,3)
Storey GP, Gonzalez-Fernandez G, Bamford IJ, Hur M, McKinley JW, Heimbigner L, Minasyan A, Walwyn WM, Bamford NS. eNeuro. 2016 Jan-Feb; 2016 Feb 2.
Full List of PubMed Publications
- Bamford NS, Wightman RM, Sulzer D: Dopamine's Effects on Corticostriatal Synapses during Reward-Based Behaviors. Neuron. 2018 Feb 7. PMID: 29420932
- Storey GP, Gonzalez-Fernandez G, Bamford IJ, Hur M, McKinley JW, Heimbigner L, Minasyan A, Walwyn WM, Bamford NS: Nicotine Modifies Corticostriatal Plasticity and Amphetamine Rewarding Behaviors in Mice(1,2,3). eNeuro. 2016 Jan-Feb; 2016 Feb 2. PMID: 26866057