Brain
The embryonic brain develops through the enlargement of neural tube vesicles, first forming three primary vesicles and later five secondary vesicles.
Human Brain, Movement Disorders & Biomarkers
Movement disorders encompass a variety of neurological conditions that lead to unusual or involuntary movements. These are often categorized as either hyperkinetic (excessive movement) or hypokinetic (reduced movement). Typically, these disorders arise when specific brain regions that control movement—such as the primary motor cortex, basal ganglia, cerebellum, and thalamus—are damaged or not functioning correctly.
To learn more about the causes, types, and treatments of movement disorders, explore further in this Cleveland Clinic resource.
For instance, Parkinson’s Disease and Huntington’s Disease showcase how basal ganglia dysfunction can lead to severe motor and cognitive challenges. Meanwhile, conditions like Tourette Syndrome and Dystonia highlight the diverse range of movement disorders that can occur due to these brain circuit issues. This summary helps illustrate the complex connections between these disorders and their effects on our movement and overall brain function.
| Disorder | What It Is | Movement Disorder? | Neurodegenerative Disorder? |
|---|---|---|---|
| Parkinson’s Disease | A condition caused by the loss of dopamine-producing neurons in the brain, leading to tremors, stiffness, and slowed movement. | Yes | Yes |
| Huntington’s Disease | A genetic disorder that causes the breakdown of nerve cells in the brain, resulting in uncontrolled movements and cognitive decline. | Yes | Yes |
| Chorea | Characterized by irregular, involuntary movements that can happen in various conditions, including Huntington’s Disease. | Yes | Yes (if related to HD) |
| Progressive Supranuclear Palsy (PSP) | A neurodegenerative disorder that leads to issues with balance, rigidity, and problems with eye movements. | Yes | Yes |
| Dystonia | A movement disorder that causes sustained muscle contractions and abnormal postures, often stemming from basal ganglia issues. | Yes | No |
| Tourette Syndrome | A condition marked by repetitive tics, both motor and vocal, linked to dysfunction in the basal ganglia. | Yes | No |
| Wilson’s Disease | A genetic disorder that causes copper accumulation in the body, leading to various movement issues and cognitive problems. | Yes | No |
| Essential Tremor | A common movement disorder that results in rhythmic shaking, primarily in the hands, potentially linked to basal ganglia circuitry. | Yes | No |
Subcortical region
The subcortical region of the brain consists of structures that lie beneath the cerebral cortex and play essential roles in regulating various functions, including movement, emotions, memory, and autonomic processes.
Cerebral cortex
The cerebral cortex is the outermost layer of the brain, responsible for higher-order brain functions such as perception, cognition, and voluntary movement. It consists of several regions that are divided based on their location and function:
Basal Ganglia Circuits
The basal ganglia is a network of subcortical brain structures distributed across the telencephalon, diencephalon, and mesencephalon (midbrain).
Substantia nigra
The substantia nigra is considered part of both the basal ganglia and the midbrain due to its anatomical location and its functional role within these brain systems.
Spiny Projection Neurons (SPN)
Spiny Projection Neurons (SPNs), specifically Medium Spiny Neurons (MSNs), are a predominant type of neuron found in the striatum, which is part of the basal ganglia in the brain.
Neurotransmitters (Amino Acid)
Glutamatergic neurons are a type of neuron that primarily release glutamate, the main excitatory neurotransmitter in the brain. GABAergic neurons are a type of inhibitory neuron in the central nervous system (CNS) that primarily use gamma-aminobutyric acid (GABA) as their neurotransmitter.
Neurotransmitters (Catecholamine)
The term “catecholamine” typically describes organic compounds that contain a catechol nucleus, characterized by a benzene ring with two adjacent hydroxyl groups, along with an amine group.
Dementia
Dementia is defined as the loss of intellectual functions (such as thinking, remembering, and reasoning) severe enough to interfere with a person’s daily functioning. It is not a disease in itself but a group of symptoms that may accompany certain diseases or physical conditions.
Parkinson’s disease - Biomarkers
Parkinson’s Disease (PD) is the second most common neurodegenerative disorder, characterized by the loss of dopaminergic neurons and the accumulation of aggregated α-synuclein, mainly in the substantia nigra pars compacta (SNpc) of the midbrain.
Dystonia - Biomarkers
There is currently no biomarker of dystonia and no gold-standard test for its diagnosis.