Topic 6: Brain Control of Human Movement Flashcards
3 stages of movement control
- Determines what needs to be done (Prefrontal Cortex): Identifies the goal of the movement and best strategy to accomplish goal
- Plans the specific movement (Motor cortex): Specific sequences of muscle activations and patterns required to do the movement
- Execute the plan (Spinal Cord): Activation of the motor neurons to do the movement and make minor adjustments
- Also have input from cerebellum and basal ganglia at stage 2
Prefrontal Cortex
- Highest in the chain of command and the greatest complexity
- Identifies a goal and determines what needs to be done to accomplish this
- Highly connected with sensory cortex
Executive Function
- Higher cognitive processes for planning, organizing, and controlling thoughts, speech, and behaviour
- Involves a wide-range of skills
Executive Functions involvement in movement
- Goal-directed actions
- Organizing
- Planning
- Directing: send info to next processing system - Attention
- Multitasking: allocating effectively among tasks performed simultaneously
- Response inhibition: respond effectively with distractions/irrelevant information
Executive Function and aging
EXECUTIVE FUNCTION DECLINES WITH AGE
- Lesions in white matter
- loss of grey matter
- loss of dendritic branching
CHANGES ARE HIGHLY VARIABLE
- Decline can be minimal in health adults
- Influenced by things like lifestyle, education, genetics
AGING RELATED DELINES IN:
- overall processing speed
- problem solving ability (Goal-directed actions)
- Controlling attentional resources (Attention)
Changes in gait parameters with age
- Decrease in gait speed and step length
- Increase in step time and variability in these parameters
- Reduced executive function may be an important driver of these changes
- healthy older adults may have little to no change
Executive Function and Gait
GAIT IS A COMPLEX MOTOR TASK THAT USES EXECUTIVE FUNCTION
- not fully managed by CPGs
- EF needed to plan, organize, and direct movements
- Often must also divide attention to other tasks
EF ALLOWS EFFECTIVE DIVISIONS OF ATTENTION BETWEEN GAIT AND OTHER TASKS (multitasking)
Area 6 involvement in the planning of movement
- Creates movement plans and holds them until ready to execute (Active just before movement occurs)
- Plans must be highly integrated with sensory information
- Details of coding taking place remains unclear
Premotor area involvement in planning of movement
Selection of best motor plans based on current sensory information
Supplementary Motor Area in planning of movement
- More Complex motor sequences often with bilateral connections
- May be more internally driven (remembering sequences)
Measuring the planning of movement
Instruction stimulus
- Red light where movement will need to be
- PMA neuron begins firing
Trigger Stimulus
- Blue light tell it to act
- PMA neuron stops firing soon after the action is made
Mirror Neurons
Exist in the PMA
- Respond when movement is imagined or watched
- Each cell has very specific movement preference
May be part of an extensive brain system for understanding actions and intentions of others
Primary motor cortex involvement in movement planning
- Transforms the motor plan into specific movement patterns
- Motor map masks the deeper complexity
- Very different from lower motor neurons
- Complex and overlapping neurons work together to control specific movements
- Coding related to direction and force of movement
Premotor lesions
AREA 6
- Difficulty choosing the correct or appropriate sequence of muscle actions needed to accomplish a goal
Primary motor region lesions
AREA 4
- While the appropriate action may be taken, there is difficulty in the execution of the task
- Weakness, lack of coordination, or even complete paralysis