reticular formation, basal ganglia Flashcards
What is the reticular formation?
The reticular formation is a network of nerve cells and fibers in the brain, extending from the spinal cord to the brain. It connects areas of the CNS and helps control body functions, receiving sensory input and sending out messages.
what functions does reticular formation have?
- skeletal muscle control
- facial expression
- sensations
- ANS
- endocrine system
- biological clocks
- RAS (reticular activating system)
What systems are influenced by the reticular formation?
The reticular formation influences
1. skeletal muscle activity
2. sensation
3. the autonomic nervous system (ANS),
4. endocrine system
5. consciousness.
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How is the reticular formation organized?
The reticular formation is divided into three columns: median, medial, and lateral columns, each with different-sized nerve cells.
Which chemicals are used by specialized cells in the reticular formation?
The reticular formation uses monoamines such as dopamine and serotonin to transmit messages.
How does the reticular formation connect to the brain and body?
At its lower end, the reticular formation connects with the spinal cord’s gray matter. At the upper end, it communicates with the cerebral cortex and some fibers go to the cerebellum.
What are the afferent projections to the reticular formation?
Afferent projections come from
1. spinoreticular tracts
2. spinothalamic tracts,
3. medial lemniscus
4. vestibular, auditory, visual pathways,
5. cerebellum
6. thalamus, hypothalamus, subthalamus,
7. motor and sensory cortices.
Where do efferent projections from the reticular formation go?
Efferent projections go to the
1. reticulobulbar and reticulospinal tracts,
2. the ANS,
3. corpus striatum,
4. cerebellum,
5. red nucleus,
6. substantia nigra,
7. thalamus, subthalamus, hypothalamus,
8. cerebral cortex.
What is the function of the reticular formation in muscle control?
The reticular formation helps control
1. muscle tone,
2. reflexes,
3. posture,
4. movement,
5. breathing muscles.
How does the reticular formation affect facial expression?
It controls facial muscles, enabling expressions like smiling, even in cases where other brain areas (involving corticobulbar fibers) are damaged.
How does the reticular formation influence sensation?
The reticular formation regulates how pain and other sensations are perceived by controlling a gating mechanism.
How does the reticular formation control the ANS?
It regulates both the sympathetic and parasympathetic nervous systems, influencing heart rate and digestion.
How does the reticular formation affect the endocrine system?
It influences hormone release by regulating the pituitary gland (hypophysis cerebri).
What is the reticular formation’s role in biological clocks?
It influences internal body rhythms such as sleep-wake cycles through connections with the hypothalamus.
What is the Reticular Activating System (RAS)?
The RAS, part of the reticular formation, controls alertness and consciousness by activating the cerebral cortex based on sensory inputs.
How does the reticular formation influence consciousness?
The reticular formation regulates wakefulness by sending sensory information to the brain to keep it alert. Acetylcholine helps increase brain activity during wakefulness.
What is the limbic system responsible for?
The limbic system controls
1. emotions
2. behavior
3. motivation
4. memory
located at the border between the cerebral cortex and hypothalamus.
What are the key structures of the limbic system?
The key structures are the subcallosal gyrus, cingulate gyrus, parahippocampal gyrus, hippocampus, amygdala, mammillary bodies, and anterior thalamic nucleus.
What are the pathways connecting the limbic system?
The connecting pathways are the alveus, fimbria, fornix, mammillothalamic tract, and stria terminalis.
What is the role of the hippocampus?
The hippocampus processes memory, connects with other brain areas, and plays a key role in forming new memories.
How is the hippocampus connected to other brain areas?
The hippocampus connects to other areas through pathways like the alveus, fimbria, and fornix.
What does the amygdaloid nucleus (amygdala) control?
The amygdala controls emotional responses, such as fear and pleasure, and is connected to other parts of the limbic system.
What are the afferent connections to the hippocampus?
Afferent connections to the hippocampus come from the cingulate gyrus, septal nuclei, and entorhinal cortex.
What are the efferent connections from the hippocampus?
Efferent connections from the hippocampus go to areas like the mammillary bodies, thalamus, and midbrain.
What are the functions of the limbic system?
The limbic system controls emotions, memory, autonomic and endocrine systems, and maintains homeostasis.
How does the limbic system affect memory?
The hippocampus helps form long-term memories. Damage to the hippocampus results in anterograde amnesia, preventing the formation of new memories.
How does the limbic system influence the autonomic and endocrine systems?
The limbic system regulates heart rate, digestion, and hormone release via its connection with the hypothalamus.
How does the limbic system maintain homeostasis?
The limbic system responds to emotional stress and environmental changes to maintain bodily balance.
What are the basal ganglia responsible for?
The basal ganglia control voluntary movements, stop unwanted movements, and are involved in cognitive functions.
What are the five main nuclei of the basal ganglia?
The five main nuclei are the caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamic nucleus.
Where is the caudate nucleus located?
The caudate nucleus is a C-shaped structure with a head, body, and tail, located in the cerebral hemisphere.
What is the role of the putamen?
The putamen is involved in receiving input related to movement and sensory processing from the cortex.
What is the function of the globus pallidus?
The globus pallidus sends inhibitory signals to the thalamus and is involved in both the direct and indirect pathways of the basal ganglia.
How are the caudate nucleus, putamen, and globus pallidus related?
Together, they form the corpus striatum, which is key to motor control.
What is the role of the substantia nigra in the basal ganglia?
The substantia nigra produces dopamine and is involved in regulating movement via its two parts: pars compacta and pars reticularis.
What is the function of the subthalamic nucleus?
The subthalamic nucleus releases glutamate and is part of the indirect pathway in the basal ganglia.
What are the afferent inputs to the basal ganglia?
The basal ganglia receive input from various parts of the cortex, with the putamen primarily receiving input from motor and sensory areas.
What is the function of the direct pathway in the basal ganglia?
The direct pathway facilitates movement by disinhibiting the thalamus, allowing it to excite the motor cortex.
What is the function of the indirect pathway in the basal ganglia?
The indirect pathway reduces cortical activity and suppresses unwanted movements by inhibiting the thalamus.
How does dopamine affect the basal ganglia pathways?
Dopamine activates the direct pathway via D1 receptors and inhibits the indirect pathway via D2 receptors, promoting movement.
What is the role of acetylcholine in the basal ganglia?
Acetylcholine promotes the indirect pathway and helps suppress unnecessary movement.
How do lesions in the direct pathway affect movement?
Lesions in the direct pathway result in hypokinetic disorders, such as Parkinson’s disease, causing bradykinesia and akinesia.
How do lesions in the indirect pathway affect movement?
Lesions in the indirect pathway lead to hyperkinetic disorders, such as Huntington’s disease, causing involuntary movements.
What is Parkinson’s disease?
Parkinson’s disease is a neurodegenerative disorder caused by dopamine loss in the substantia nigra, leading to hypokinetic symptoms like bradykinesia, tremors, and rigidity.
What are the symptoms of Parkinson’s disease?
Symptoms include bradykinesia, pill-rolling tremor, hypertonia, cogwheel rigidity, mask-like face, and slow, shuffling gait.
How is Parkinson’s disease treated?
Treatment for Parkinson’s includes L-DOPA, which is converted to dopamine in the brain.
What is Huntington’s disease?
Huntington’s disease is a hereditary disorder caused by the loss of GABA and cholinergic neurons in the striatum, leading to hyperkinetic symptoms and cognitive decline.
What are the symptoms of Huntington’s disease?
Symptoms include chorea, athetosis, dementia, and personality changes.
What is hemiballismus?
Hemiballismus is characterized by violent, swinging movements of one limb, usually caused by a stroke affecting the subthalamic nucleus.
What is dystonia?
Dystonia is a movement disorder characterized by slow, twisting movements or abnormal postures.
What is Tourette syndrome?
Tourette syndrome involves both motor tics (involuntary movements) and vocal tics (involuntary sounds or words).
