Neural Circuits Flashcards
Pyramidal (corticospinal) tract
Main pathway for voluntary movement control
Upper Motor Neurons
Originate in the cerebral cortex or brainstem with lower motor neurons
Voluntary movement
Corticobulbar Tract
Connects the cerebral cortex to the brainstem nuclei of cranial nerves
Controls voluntary movements of muscles in the face, head and neck.
Lower Motor Neurons
Connect UMNs to skeletal muscles, forming motor units
Voluntary and involuntary
Reflex Arc
Bypasses the brain
Involves sensory neurons, spinal cord and motor neurons
Produces rapid, automatic responses
Involuntary
Neural Circuit
Network of interconnected neurons that process specific types of information to carry out particular functions when activated
Functions of neural circuits
- process various types of information
- adapt to new experiences
- coordinate complex behaviors
Neural pathways in motor control
Pyramidal tracts
Extrapyramidal tracts
Pyramidal and Extrapyramidal tracts transmit motor commands from the _ to the _ to the _
Brain, spinal cord, muscles
How are neural circuits laid out?
Multiple layers of neurons with feedback loops.
Allows for dynamic interactions and adjustments
What are neural circuits involved in?
Processing and integrating information
Allowing for complex responses
Are neural circuits specialised or do they serve broader functions?
Each neural circuit is often specialised for a particular task.
Adapting its output based on the context
What happens if there is dysfunction in neural circiuts?
Various neurological conditions
Layout of Neural Pathways
More linear than circuits
Consisting of direct connects that do not typically involve feedback mechanisms
What is the primary focus of neural pathways?
Transmitting signals between different regions without significant processing
Are neural pathways specialised or do they serve broader functions?
Serve broader functions related sensory input or motor input without being dedicated to specific tasks
What happens if there is damage to neural pathways?
Damage to specific pathways can lead to sensory deficits.
The neural circuits responsible for the control of movement can be divided into …
Four distinct, highly interactive subsystems:
* Local circuits
* Upper motor neurons circuit
* Cerebellar circuits
* Basal ganglia circuits
Location of local circuits
Within the grey matter of the spinal cord
Components of local circuits
Lower motor neurons
Local circuit neurons
Function of local circuits
Responsible for reflex actions and basic motor control, coordinating movements at the level of the spinal cord
Pathways used by local circuits
Spinal reflex pathways
They receive inputs from sensory pathways and descending pathways from upper motor neurons
Diseases associated with local circuits
Multiple sclerosis
Cervical spondylotic myelopathy
Traumatic spinal cord injury
Location of upper motor neurons circuit
Primarily in motor cortex, premotor cortex and brainstem nuclei
Components of upper motor neurons circuit
Neurons with cell bodies in brainstem or cerebral cortex
axons descending to synapse with local circuit neurons
Function of upper motor neurons circuit
Initiation of voluntary movements, control of complex movement
Pathways connected to upper motor neurons circuit
Corticospinal Tract
Corticobulbar Tract
Corticorubal, Corticotectal and Corticoreticular Tracts
Corticospinal tract
Directly connects the primary motor cortex to spinal cord lower motor neurons.
Corticobulbar Tract
Connects the motor cortex to cranial nerve nuclei in the brainstem for facial and neck muscle control.
Corticorubral, Corticotectal, and Corticoreticular Tracts
Modulate other
pathways like rubrospinal, tectospinal, and reticulospinal tracts
Diseases associated with upper motor neurons circuit
Amyotrophic Lateral Sclerosis (ALS)
Primary Lateral Sclerosis (PLS)
Stroke
Location of cerebellar circuits
In the cerebellum at the back of the brain
Function of the cerebellar circuits
Detects and corrects motor error between intended and performed movements
Circuit of the cerebellar circuits
Acts via afferent pathways to upper motor neurons
Pathways connected to the cerebellar circuits
Receives inputs from various sensory systems (via pontine nuclei) and sends outputs to upper motor neurons via thalamic relay nuclei
Diseases associated with Cerebellar circuits
Cerebellar ataxia
Some symptoms in Parkinson’s disease
Huntington’s disease
Location of basal ganglia circuits
Embedded in the depths of the forebrain
Function of basal ganglia circuits
Regulates initiation and inhibition of movement
Involved in action selection and learning motor skills
Suppresses unwanted movements
Primes upper motor neuron circuits for movement initiation
Pathways connected to the Basal ganglia circuits
The striatum sends output to both the direct pathway (facilitating movement) and indirect pathway (inhibiting unwanted movements) affecting thalamic activity that influences upper motor neurons.
Corticostriatal pathway is interconnected with the cortex for feedback loops
Diseases associated with the basal ganglia circuits
Parkinson’s
Huntington’s
Myotatic Reflex Mechanism:
Neural circuit where muscle spindle afferents detect stretch and directly activate alpha motor neurons, resulting in muscle contraction.
This rapid response is crucial for maintaining posture and balance, demonstrating the efficiency of spinal reflex pathways in motor control.
Baroreceptor Reflex Functionality:
Integration of sensory input and autonomic motor output
Baroreceptors in blood vessels detect pressure changes and modulate heart rate and vascular resistance.
This reflex is vital for cardiovascular stability, ensuring adequate blood flow during physical activity and stress
