Neuroscience Assessment Quiz

Motor Control

• Movement is produced by complex neural networks, activating and coordinating muscles and limbs.
• Motor control involves reflexive, reactive, and voluntary components.
• Mechanisms include sensory (afferent) input, cortical processing, and motor/action (efferent) coordination/output.
• Simple behaviors, like playing tennis, utilize multiple brain areas.
  • Visual cortex processes visual information.
  • Premotor cortex plans actions.
  • Amygdala and hypothalamus regulate motivation and alertness.
  • Motor cortex sends signals to spinal cord to initiate movement.
  • Posterior parietal cortex integrates sensory input.
  • Basal ganglia executes motor tasks.
  • Cerebellum corrects errors for accurate performance.

Nervous System

• The nervous system has central (CNS) and peripheral (PNS) components.
  • CNS includes the brain and spinal cord.
  • PNS includes peripheral nerves and ganglia.
  • CNS and PNS are anatomically separate but functionally interconnected.
• The CNS and PNS constantly communicate to receive sensory information and send motor commands.
• Two major cell types in the nervous system are neurons and glia.
  • Neurons have dendrites (receiving input), cell body (processing), and axons (transmitting output).
  • Glial cells support neurons.
  • Neurons have myelinated or unmyelinated axons and presynaptic boutons.
  • Sensory neurons are 'afferent'; motor neurons are 'efferent'; interneurons connect within the system.

Sensory Neurons

• Function to provide the CNS with information from the body.
• Cell bodies reside in the dorsal root ganglia.
• Approximately 5 million sensory neurons in the system.
• Receive information from receptors (muscle, joint, skin).
• Sensory information is sent to the spinal cord, then up to higher brain centers.

Motor Neurons

• Function: control muscle contraction.
• Cell bodies are located in the spinal cord's ventral horn.
• They receive input from sensory neurons and interneurons in the spinal cord and higher brain centers.
• Numbering in the hundreds of thousands.

Interneurons

• Function: receive multiple inputs, process information, and send output to multiple locations.
• Vastly outnumber sensory and motor neurons.

Central Nervous System (CNS)

• Consists of several interconnected regions, including the spinal cord, brainstem (medulla, pons, midbrain), and the forebrain (cerebrum).

Spinal Cord

• Grey matter contains neuron cell bodies and unmyelinated axons.
• White matter consists of myelinated axons in columns (dorsal, ventral, lateral).
• Contains sensory input (dorsal horn), motor output (ventral horn), and interneurons.

Brainstem

• Composed of the medulla, pons, and midbrain.
• Critical for life support functions and reflexive actions, such as eye movements and auditory/visual reflexes.

Cerebral Cortex

• Deeply folded, increasing surface area.
• Organized into lobes (frontal, parietal, occipital, temporal), with specific functions:
  • Frontal lobe: movement, planning, reasoning.
  • Parietal lobe: bodily (somatic) sensation, spatial processing.
  • Occipital lobe: visual processing.
  • Temporal lobe: hearing, smell, taste, visual perception.

Cerebral Cortex (continued)

• Many areas process sensory or motor commands (unimodal).
• Association areas combine information from multiple areas for complex actions (e.g., perception, movement, motivation).

White and Grey Matter

• White matter's axons carry information. Grey matter's cell bodies process the information.

Organization of Spinal Cord

• Dorsal horn receives sensory input; ventral horn directs motor output.
• Organization (e.g., from medial to lateral) relates to body part representation.

Motor Units

• A motor unit consists of a motor neuron and all the muscle fibers it innervates.
• Different muscles have different ratios of fibers per motor neuron.
• Recruitment of motor units is important for controlling force during movement.

Motor Neuron Pool

• All the motor neurons that innervate a specific muscle.

Muscle Fibers

• Extrafusal muscle fibers generate force.
• Intrafusal muscle fibers are within the muscle spindle (proprioceptors).
• Two main types of motor neurons: alpha and gamma.

Types of Muscle Fibers

• Extrafusal muscle fibers are responsible for muscle contraction.
• Intrafusal muscle fibers (within muscle spindles) detect muscle length/stretch and rate of change.  

Sensory Systems

• Detect body position, movement, and external stimuli.
• Reception of signals is from the periphery, and the information is integrated and interpreted by the CNS.
• Information travels to and from the spinal cord.
• Includes proprioception (sense of position and movement of body in space), kinaesthesia (sense of movement), and exteroception (external environment sense).
• Receptors (thermal, mechanical, chemical) in the periphery trigger action potentials and send signals to the CNS. This information is processed through sensory pathways in the spinal cord into the brain. Further processing occurs within the cerebrum, brainstem, and cerebellum.

Peripheral Receptors

• Cutaneous receptors (touch, pressure, temperature, pain).
• Joint receptors (joint position and movement).
• Muscle spindles (muscle length and stretch).
• Golgi tendon organs (muscle tension/force).

Four Types of Cutaneous Receptors

• Slow-adapting (Merkel, Ruffini).
• Fast-adapting (Pacinian, Meissner). 

Joint Receptors

• Located within the joint capsule.
• Sensitive to changes and extremes of joint movement.

Muscle Spindles

• Encapsulated sensory organs.
• Located parallel to muscle fibers.
• Monitor changes in muscle length.

Two Types of Intrafusal Fibers

• Nuclear bag fibers (dynamic, and static).
• Nuclear chain fibers (static, and length information).

Golgi Tendon Organs

• Series with skeletal muscles.
• Respond to muscle tension/force.

Spinal Reflexes

• Involuntary, stereotyped responses to stimulus.

Motor Control Pathways

• Sensory and Motor. 

Visual System – Central Visual Pathway

• Information travels from the retina through the optic nerve.
• Pathways branch to different areas of the brain (superior colliculus, pretectal region, lateral geniculate nucleus) processing visual information and determining movements.
• The primary visual cortex (V1) plays a role in initial visual processing.
• Higher-order visual cortex (processing specific features like form or movement) processes information for actions.

Visual Pathway Deficits

• Optic ataxia (parietal lobe damage; difficulty with visually-guided movements).
• Visual agnosia (temporal lobe damage; difficulty recognizing objects despite being able to see them).

Vestibular System

• Detects head position/movement.
• Plays a role in balance, head and neck position, vestibular reflexes, and eye movements (e.g., visual fixations/compensations).
• Three semicircular canals detect angular acceleration/rotational movement.
• Two otolith organs detect linear acceleration/static orientation to gravity.

Vestibular Pathway

• Sensory neurons transmit information to the four vestibular nuclei in the brainstem.

Factors Affecting Performance and Learning

• Speed-accuracy tradeoff.
• Information processing capacity.
• Response time.

Measuring Performance

• Production measures record the action.
• Outcome measures record the result of the action.
• Human judgment, video recording, high-speed filming and computer analysis are used to evaluate performance.
• EMG, EEG, and fMRI help measure physiological activity during performance.

Four Measures of Error

• Constant error (CE): deviation from the target.
• Variable error (VE) : variability of the responses.
• Total variability (E): overall amount of error.
• Absolute error (AE): sum of absolute errors without direction.

Stages of Learning

• Cognitive stage: understanding task elements.
• Associative stage: connections and refining movement.
• Autonomous stage: efficient, automatic movement.
• Learning involves continuous improvement.

Test your knowledge of sensory and motor neurons, including their functions and locations. This quiz also covers concepts related to performance assessment in the central nervous system. Dive into the details of neuron types and their roles in motor performance.