Flashcards in Basal Ganglion Deck (75):
What 2 histologically similar structures make up the striatum?
- Caudate nucleus
What is the function of the striatum?
What 2 structures make up the globus pallidus?
- Internal/ external globus palldius
What is the efferent limb of the basal ganglion?
What is the afferent limb of the basal ganglion?
What structures make up the lenticular nucleus?
- Globus pallidus
What substance is produced in the substantia nigra?
What 2 structures make up the pedunculopontine tegmental nucleus?
- Pars compacta (PPPNc)
- Pars dissipata (PPPNd)
What neurotransmitter is utilized in the pars compacta?
What neurotransmitter is utilized in the pars dissipata?
What functions does the peduncolopontine tegmental nucleus play?
Postural control and locomotion in the absence of dopamine
What does the ventral tegmental area synthesize?
What chemicals influence the ventral tegmental area? What receptors do they act on?
Endorphins act on opiate receptors
What structure does the ventral tegmental area's axons project to?
The Nucleus Accumbens
What 2 neurotransmitters are balanced by the nucleus accumbens? What is the function of each in the "reward circuit"?
Serotonin: Safety and inhibition
Which cortex acts as a relay in the reward circuit?
What is the function of the basal ganglion?
Smooths integration of emotions, thoughts, and physical movements
What is the "Action Selection Hypothesis"?
- Basal ganglion determines which of the potential actions generated by the cerebrum will be acted upon with dopamine acting as the reward system to influence future actions
What is the function of the direct pathway?
Promotes execution of correct execution and sequencing of motor command
What is the function of the indirect pathway?
Suppresses commands of movements opposing the correct movement, and turns down motor groups when it is not their turn in the sequence of events
Describe the direct pathway.
- Cortex facilitates the inhibitory neurons of the striatum
- Striatum inhibits the inhibitory neurons of the internal/ medial globus pallidus
- Thalamus disinhibited by striatums action of IGO
- Thalamus stimulates the motor cortex
- Motor cortex simulates contralateral lower motor neuron
What is the overall effect of the direct pathway?
Motor thalamus disinhibited, facilitating the motor cortex
How does the internal globus pallidus reach the VA-VL motor nuclei of the thalamus?
Via the Ansa lenticularis nad lenticular fasciculus
How does the motor cortex reach the lower motor neurons in the spinal cord?
Via the lateral corticospinal tract
Describe the indirect pathway.
- Cortex stimulates inhibitory neurons of the striatum
- Striatum inhibits the inhibitory neurons of the external globus pallidus
- Subthalamic nucleus is disinhibited by the striatum acting on the EGP
- Subthalamic nucleus facilitates the inhibitory neurons of the internal globus pallidus
- Internal globus pallidus inhibits the motor thalamus (via the ansa lenticulars and lenticular fasciculus
- Thalamus sends a decreased drive to the motor cortex and contralateral lower motor neuron
What neurotrasmitter facilitates most of the basal ganglion? What structure does not utilize this NT for facilitation?
- Substantia nigra ultilizes dopamine
What neurotransmitter inhibits most of the basal ganglion? What connection has an added NT?
- Striatum to globus pallidus utilizes Enkephalin
What connections int he direct pathways are tonically active?
- Subthalamus to internal globus pallidus
- Internal globus pallidus to thalamus
At what level of conciousness does the basal ganglion function?
Sub-voluntary/ automatic/ sub-concious
What 2 structures modulate pathways in the basal ganglion? What neurotransmitter is utilized by each?
- Substantia nigra (dopamine)
- Striatal interneurons (ACh)
How does the subtantia nigra modulate the basal ganglion?
- Facilitates direct pathway by increasing disinhibition of the thalamus through facilitation of striatum to IGP
- Inhibits indirect pathway by inhibiting the subthalamus through the EGP
How do the striatal interneurons modulate the basal ganglion?
- Pedunculopontine tegmental nuclei of midbrain activate ACh receptors in striatum
- Inhibits direct pathway by disinhibiting the IGP, which then inhibits the motor thalamus
- Facilitates the indirect pathway by increasing disinhibition of the subthalamus through facilitation of the EGP
What artery supplies the lenticular nucleus, striatum and internal capsule?
- Lateral lenticular striate artery branches of middle cerebral artery
What arteries supply the caudate nucleus?
- Anterior cerebral
- Medial striate arteries
What are the 5 parallel loops of the basal ganglion?
Describe the 5 step motor loop.
- Somatosensory/ primary motor/ pre-motor cortex
- Substantia nigra/ IGP
- VA-VL of thalamus
- Supplemental motor area, premotor, primary motor
Describe the 5 step limbic loop.
- Medial and lateral temporal lobe, hippocampal formation
- Pallidum, IGP, SN
- MD, VA of thalamus
- Anterior cingulate, orbital frontal cortex
Describe the 5 step occulomotor loop.
- Posterior parietal, prefrontal
- Substantia nigra, IGP
- VA, MD of thalamus
- Frontal eye field, supplementary eye field
Describe the 5 step associative loop.
- Posterior parietal, premotor
- SN and IGP
- VA, MD of thalamus
What are 3 diseases of the caudate nucleus?
- Tourette syndrome
What pathway is affected by chorea?
Indirect pathway (at striatum to external globus pallidus)
How will an individual present with chorea?
- Random, uncontrolled jerking of trunk ,extremities and head
- Facial grimacing
What neurotransmitter can help turn the indirect pathway "back on" in Chorea?
What structure in addition to the Caudate nucleus is affected in Tourette Syndrome?
What loop is affected by Tourette Syndrome?
Limbic loop (inhibitory limbic system acts on motor cortex) (motor striatum generates tics)
What 2 pathologies affects the Putamen?
What is dystonia?
Slow, twisting, involuntary contorting movement that is sustained and repreated
What other pathology is associated with Athetosis?
What is the main symptom of Athetosis?
Slow worm-like movements of distal limbs/ fingers
What pathalogy is associated with the Subthalamus?
What is the major symptom of Ballism?
- Quick continuous flinging of the limbs
What pathology is associated with the Substantia Nigra?
How are the pathways affected by the Subtantia Nigras lack of dopamine cells in Parkinsonism?
- Decreased direct pathway
- Increased indirect pathway
How will passive movement through the joint be affected by Parkinsonism?
- Rigidity through the entire joint range
What is Palilalia (associated with Parkinsonism)?
What is Hypophonia (associated with Parkinsonism)?
What is Bradyphrenia (associated with Parkinsonism)?
What is Retropulsoin (associated with Parkinsonism)?
Repetition of motor acts
What is the frequency of Parkinsonism tremors?
3 - 6 Hz
How are hyperkinetic disorders treated?
- Raising ACh
- Lowering Dopamine
Identify the basal ganglion and cerebellum as either excitatory or inhibitory.
Basal ganglion: Inhibitory
Does the BG or Cerebellum affect cognitive and motivational aspects of movement?
Is the BG or Cerebellum capable of learning?
Does the BG or Cerebellum permit smooth progression from one movement to the next?
Does the BG or Cerebellum optimize patterns of muscle activation so that the desired goal is achied in the most efficient way?
Does the BG or Cerebellum perform a gating function?
Is the BG or Cerebeluum involved with force, frequency, load, velocity, and movement direction?
Does the BG or Cerebellum prepare for movement (targeting location in space, directing movement and muscle pattern)?
Does the BG or Cerebellum activate during memorize motor tasks and therefore contribute to the automatic execution of a learned motor plan?
Does the BG or Cerebellum aide in visual tracking?
Does the BG or Cerebellum help predict movement occurring outside the body?
Does the BG or Cerebellum suppress unwanted movement?
Does the BG or Cerebellum affect muscle tone and participate in generation, switching and termination of movement as dictated by situational demands and emotional or attentive states?
Does the BG or Cerebellum deal with cognitive and motivational aspects of movement?