Basal Ganglia & Parkinson’s Disease
What subcortical structure in the basal ganglia is overactive in Parkinson’s disease, leading to increased inhibition of motor commands?
Subthalamic nucleus (STN)
Name the four lobes of each cerebral hemisphere.
Frontal, parietal, temporal, occipital
How many cranial nerves exit the brainstem?
10
What is the functional unit of the nervous system that generates and transmits electrical signals?
Neuron
Name the three meninges that protect the CNS.
Dura mater, arachnoid mater, pia mater
Which neurotransmitter’s loss in the striatum leads to disinhibition of the STN in Parkinson’s disease?
Dopamine
Which association tract connects temporal/parietal areas to frontal regions and is essential for language function?
Arcuate fasciculus
Which cranial nerve is responsible for tongue movement?
Hypoglossal nerve (XII)
Name the site where a motor neuron communicates with a muscle fiber.
Neuromuscular junction
What fluid circulates through the ventricles and central canal of the CNS?
Cerebrospinal fluid (CSF)
How does the STN affect the globus pallidus, and what is the consequence for thalamic output in Parkinson’s disease?
The STN excites the globus pallidus, which becomes overly inhibitory, resulting in weak thalamic output and reduced cortical motor commands.
Which descending tract carries signals from the cortex to brainstem nuclei controlling speech muscles?
Corticobulbar tract
Name the three levels of the brainstem from superior to inferior.
Midbrain, pons, medulla
What neurotransmitter is released at the neuromuscular junction to trigger muscle contraction?
Acetylcholine
Which artery is critical for supplying blood to cortical areas involved in speech and language?
Middle cerebral artery
Deep brain stimulation (DBS) targets which structure to reduce its overactivity and improve motor function in Parkinson’s disease?
Subthalamic nucleus (STN)
Identify the type of tract that connects the two hemispheres of the brain.
Commissural tract
Which cranial nerve is both sensory and motor for swallowing and speech control?
Vagus nerve (X)
Explain the sequence of events in an action potential from dendrites to axon terminals.
Electrical signal depolarizes dendrites, soma, propagated along axon, reaches terminal, neurotransmitter released into synaptic cleft, binds postsynaptic receptors.
What is the function of the thalamus in sensory processing?
It relays sensory information (except smell) to the cerebral cortex and processes basal ganglia output.
Explain why DBS sometimes worsens speech and swallowing in patients with Parkinson’s disease despite improving limb movement.
DBS modulates STN activity, which affects basal ganglia-thalamocortical loops controlling speech and swallowing. Variability in individual neural circuits can lead to unintended inhibition of these functions.
Explain how cortical-cerebellar loops contribute to speech production.
Cortical-cerebellar loops process motor commands, coordinate timing, refine articulatory sequences, and ensure smooth, precise speech movements.
Describe the role of the brainstem in relaying sensory and motor information between the cortex and body.
The brainstem contains nuclei and fiber tracts that transmit sensory input to the cortex and motor output to muscles, serving as a vital integration and relay hub for motor and sensory pathways.
How do glial cells support neuronal function?
Glial cells provide metabolic support, insulation (myelin), protection, and help maintain homeostasis in the CNS and PNS.
Explain the functional significance of the corticospinal tract in voluntary movement.
It conveys motor commands from the cortex to spinal motor neurons, enabling precise voluntary movements of limbs and trunk.