Question

You are a neurologist working on treatments for Parkinson's disease. You think you may have discovered a breakthrough. One of your patients, who is a drug addict, is taken to the ER in dire straits. Apparently, the patient thought they were taking heroin but instead took Lysergic Acid Diethylamide, or LSD (I said they were an addict; I didn't say they were a smart one.) Once you have the patient stabilized, you realize that their normal Parkisonian symptoms were remarkably absent. Turns out, LSD is a D₂ receptor agonist, meaning it mimics Dopamines effect on the basal ganglia circuit.

a. Outline and explain the NORMAL WORKING of the basal ganglia circuit. Be sure to include all of the relevant structures, the connections (and their sign - positive/negative) between structures. Finally, explain how the connections between structures produces movement, or the lack thereof.

b. Explain how the circuit is ALTERED in Parkinson's. You DO NOT need to re-explain anything from part a; rather, simply start with how the circuit looks in Parkinson's (what connections are lost/gained) and why that produces your patients's Parkinsonian symptoms.

c. IN NO MORE THAN TWO SENTENCES, explain how the administration of LSD (note: EVEN THOUGH LSD IS TECHNICALLY NON-ADDICTIVE, NO LICENSED DOCTOR WOULD EVER PRESCRIBE THIS!) alleviates your patient's symptoms. Please frame your response in terms of connections between structures and how that explains the result.

Answer 1

a) Basal ganglia is strongly with the cerebral cortex , thalamus and Brainstem as well as several other brain areas. The basal ganglia are associated with a variety of functions, including control of voluntary motor movements, procedural learning, habit learning, eye movements, cognition and emotion. Circutes within the basal ganglia system: The projections from the medium spiny neurons of the caudate and putamen to the internal segment of the globus pallidus and substantia nigra pars reticulata are part of a 'direct pathway ' and as just described, serve to release the upper motor neurons from tonic inhibition. The basal ganglia refers to a group of subcortal nuclei responsible primarily formotor control, as well as other roles such as motor learning, executive functions and behaviours and emotions. Disruption of the basal ganglia network forms the basis for several movement disorder.

b) Parkinson's disease is a degenerative, progressive disorder that affects nerve cells in deep parts of the brain called the basal ganglia and substantia nigra. Nerve cells in the substantia nigra produce the neurotransmitter dopamine and are responsible for relaying messages than plan and control body movement. Degradation of nerve cells cause nerve cell die or become impaired, losing the ability to produce an important chemical called dopamine. The symptoms are tremors, slowness and shiffness. These involuntary movements begin, in part ,in the brain where the production of dopamine is impaired.

c) LSD is white or clear, water soluble crystal that can be crushed into powder and dissolved. The most common form of LSD is asva liquid that has been transferred into a small paper square ( known as blotter) or as a microdot tablet. The potency of each LSD blotter tab or pills between 20 and 80 microorganisms, and users usually chew or swallow them, allowing the drug to be absorbed through the gastrointestinal tract. It ia also inhaled or injected.