Flexion Reflex Pathways, Upper Motor Neuron Control Overview, Eye Movements Overview, Cortical Structure Overview, Language and Brain Localization, Weekly Quiz Questions, Spinal Reflexes Overview, Neuroscience COGS1000

Flexion Reflex Pathways

Involves withdrawing a limb from a painful stimulus by exciting flexor muscles and inhibiting extensor muscles.

Nociceptive Sensory Fibers

Sensory fibers that respond to pain stimuli and trigger the flexion reflex.

Central Pattern Generators

Local circuits in the spinal cord controlling rhythmic movements like walking and swimming.

Stance Phase

Phase of locomotion when the limb is on the ground.

Swing Phase

Phase of locomotion when the limb is off the ground.

Spinal Cord Circuitry

Includes central pattern generators adjusting timing and coordination of rhythmic movements.

Excitatory Neurons

Neurons in central pattern generators that promote limb movement.

Inhibitory Neurons

Neurons in central pattern generators that regulate limb movement.

Lower Motor Neuron Syndrome

Signs and symptoms from damage to lower motor neurons causing paralysis or weakness.

Paresis

Weakness in muscles due to damage to lower motor neurons.

Bipedal Locomotion

Walking on two legs, which places higher demands on brain centers compared to animals.

Rhythmic Movements

Controlled by spinal cord circuits, with input from higher brain centers modulating the process.

Descending Pathways

Neural pathways that regulate spinal cord responses to sensory inputs.

Postural Support

Provided by extension in the opposite limb during flexion reflex to maintain balance.

Limb Squeezing

An alternative stimulus that can trigger the flexion reflex in the absence of a painful stimulus.

Spinal Cord Neurons

Receive inputs from various sources, including upper motor neurons, in reflex pathways.

Upper Motor Neurons

Contribute inputs to spinal cord neurons in reflex pathways.

Local Circuits

Found in the spinal cord, like central pattern generators controlling rhythmic movements.

Animal Locomotion

Controlled by spinal cord circuits even after damage to higher brain centers.

Coordinated Movements

Possible in animals with spinal cord damage on a moving treadmill, indicating local circuit involvement.

Modulatory Role

Played by higher brain centers in controlling rhythmic limb movements during locomotion.

Upper Motor Neurons

Neurons originating in higher brain centers influencing local circuits in brainstem and spinal cord

Local Circuits

Neuronal circuits organizing movements by coordinating lower motor neurons

Somatotopic Organization

Spatial arrangement of lower motor neurons in spinal cord reflecting muscle innervation

Axial Muscles

Muscles related to the trunk or core of the body

Distal Muscles

Muscles located further away from the body's center, like those in the limbs

Ventral Horn

Region in the spinal cord containing lower motor neurons

Intermediate Zone

Region in the spinal cord gray matter containing local circuit neurons

Corticospinal Tract

Pathway for upper motor neuron axons from the motor cortex to the spinal cord

Corticobulbar Tract

Pathway for upper motor neuron axons from the motor cortex to the brainstem

Primary Motor Cortex

Cortical area directly controlling voluntary movements

Premotor Areas

Frontal lobe regions contributing to motor functions, distinct from primary motor cortex

Betz Cells

Conspicuous large neurons in the primary motor cortex

Pyramidal Cells

Neurons in cortical layer 5 serving as upper motor neurons

Cerebral Peduncle

Bundle of nerve fibers connecting the cerebrum to the brainstem

Internal Capsule

White matter tract carrying fibers to and from the cerebral cortex

Medullary Pyramids

Distinct structures in the medulla oblongata formed by corticospinal fibers

Hypoglossal Nucleus

Nucleus in the brainstem controlling movements of the tongue

Trigeminal Motor Nucleus

Nucleus in the brainstem governing chewing movements

Facial Motor Nucleus

Nucleus in the brainstem controlling facial muscle movements

Brodmann's Areas

Numbered regions of the cerebral cortex based on cytoarchitecture

Ventrolateral Thalamus

Thalamic region relaying inputs between basal ganglia, cerebellum, and cortex

Axons

Nerve fibers conducting impulses away from the cell body

Axial Musculature

Muscles related to the body's central axis, like those in the trunk

Distal Extremities

Body parts located far from the center, such as hands and feet

Reticular Formation

Network of nuclei in the brainstem involved in multiple vital functions

Corticopontine Tract

Projection from the motor cortex terminating in nuclei at the base of the pons

Cerebral Cortex

Outer layer of the cerebrum responsible for higher brain functions

Basal Ganglia

Group of subcortical nuclei involved in motor control and learning

Mirror motor neurons

Neurons activated when observing goal-directed actions

Conditional intention

Key role in choosing movements based on outside events

Ventrolateral subdivision

Part of premotor cortex activated when preparing or observing actions

Mirror motor system

Helps understand and imitate others' actions

Lateral premotor cortex

Affects movement selection; crucial for specific movements

Broca's area

Critical for the production of speech sounds

Supplementary motor area

Involved in starting movements based on internal cues

Motor Cortex

Brain region sending signals to spinal cord for movement

Direct Pathway

Motor cortex to spinal cord pathway for forepaw movement

Indirect Pathway

Motor cortex to spinal cord pathway via brainstem for posture adjustments

Medulla

Part of the brainstem where direct pathway transection occurred

Spinal Shock

Decreased spinal cord activity due to disrupted motor signals

Babinski Sign

Reflex where sole of foot stroking causes abnormal toe movement

Upper Motor Neuron Syndrome

Set of symptoms from damage to descending motor pathways

Decerebrate Rigidity

Rigidity of leg extensor and arm flexor muscles from lesions

Spasticity

Increased spinal cord reflex excitability due to descending pathway disruption

Clonus

Repetitive, rhythmic muscle contractions due to increased segmental circuit gain

Fine Movements Impairment

Loss of ability to execute precise movements, like finger independence

Vestibular Nuclei

Brainstem centers regulating postural reflexes and muscle excitability

Red Nucleus

Midbrain region sending signals to spinal cord for arm and hand movements

Rubrospinal Tract

Pathway from red nucleus to spinal cord controlling arm muscles

Mesencephalic Locomotor Region

Midbrain area initiating locomotion via reticulospinal neurons

Colliculospinal Tract

Direct connection from superior colliculus to spinal cord for head movements

Photoreceptors

Cells in the retina sensitive to light

Rods

Photoreceptors for night vision, low resolution

Cones

Photoreceptors for color vision, high resolution