Goal-Directed Motor Acts

What are goal-directed motor acts?

Voluntary movements performed to achieve a specific behavioural objective through coordinated activity of sensory, association, motor, basal ganglia, cerebellar, brainstem and spinal systems.

Are goal-directed movements generated by a single brain region?

No. They emerge from interactions among: Sensory systems, Association cortex, Motor cortex, Basal ganglia, Cerebellum, Brainstem, Spinal cord.

What is the core concept of goal-directed movement?

Voluntary movement arises through continuous perception–action loops linking sensory input, movement planning, execution and feedback correction.

What is the role of association cortex in motor control?

Determines behavioural goals, Decision making, Action selection.

Which association cortical regions are particularly important?

Prefrontal cortex, Posterior parietal cortex, Parietal-temporal-occipital association cortex.

What is the role of the premotor cortex (PMA)?

Movement preparation, Movement selection, Externally guided movement, Reaching and grasping.

What is the role of the supplementary motor area (SMA)?

Internally generated movement, Motor sequencing, Bimanual coordination.

What is the role of primary motor cortex (M1)?

Execution of voluntary movement, Final cortical output to the spinal cord.

What are the major motor functions of the basal ganglia?

Select desired motor programs, Suppress competing movements, Initiate movement, Control movement amplitude, Control movement vigour.

What is the key role of the basal ganglia?

Movement selection and initiation.

What are the major functions of the cerebellum?

Motor coordination, Timing of movement, Error correction, Motor learning, Prediction of movement outcomes.

What does the cerebellum continuously compare?

Intended movement vs actual movement.

What are the major motor functions of the brainstem?

Postural control, Locomotion, Eye movement control, Vestibular integration.

Why is the spinal cord called the final common pathway?

Because all descending motor commands ultimately activate spinal motor neurons.

Major functions of the spinal cord in movement?

Motor neuron activation, Reflex circuits, Pattern generation.

Why are sensory systems essential for movement?

They provide continuous feedback required for accurate motor control.

Which sensory modalities contribute to movement control?

Vision, Proprioception, Touch, Vestibular information.

What is a perception–action cycle?

A continuous loop in which sensory information guides movement and movement generates new sensory information.

What sensory systems provide information for goal-directed movement?

Vision, Somatosensation, Vestibular system, Auditory system.

Where is sensory information processed?

Primary sensory cortices, Association cortices.

What questions are answered during sensory processing?

What is the object? Where is it? Is action required?

Which structures are involved in action planning?

Prefrontal cortex, Posterior parietal cortex, Premotor cortex, SMA.

What occurs during action planning?

Selection of movement goals and motor strategies.

Which pathways execute movement?

M1, Corticospinal pathways, Brainstem pathways, Spinal motor neurons.

What forms of feedback are generated during movement?

Visual feedback, Proprioceptive feedback, Tactile feedback.

What does the brain compare during movement?

Expected outcomes versus actual outcomes.

Which systems contribute to movement correction?

Cerebellar circuits, Cortical circuits, Brainstem circuits.

What happens after movement correction?

The perception–action cycle repeats continuously.

What is the role of the prefrontal cortex in movement?

Intention formation, Goal setting, Decision making.

What question does the prefrontal cortex answer?

"What do I want to do?"

What is the role of PPC in planning movement?

Spatial awareness, Sensory integration, Target selection.

What question does PPC answer?

"Where is the target?"

What is the role of the premotor cortex in planning?

Movement preparation, Movement strategy selection.

What question does PMA answer?

"How should I move?"

What is the role of SMA in planning?

Internally generated actions, Movement sequences.

What question does SMA answer?

"What sequence of actions is required?"

Which structure is most important for movement initiation?

Basal ganglia.

What is the role of the direct pathway?

Facilitates desired movement.

What is the role of the indirect pathway?

Suppresses competing movements.

What decision do the basal ganglia make?

Whether a planned movement is released for execution.

Which cortical region generates descending motor commands?

Primary motor cortex (M1).

What is the major voluntary motor pathway?

Corticospinal tract.

Approximately what percentage of corticospinal fibres decussate?

About 90%.

Where do corticospinal fibres cross?

Lower (caudal) medulla.

What is the consequence of corticospinal decussation?

Each hemisphere controls the contralateral side of the body.

What are the major brainstem motor pathways?

Vestibulospinal, Reticulospinal, Tectospinal.

What do brainstem pathways primarily provide?

Balance, Postural adjustments, Orientation responses.

What is sensory-motor integration?

Transformation of sensory information into motor commands.

What is the major sensorimotor integration area?

Posterior parietal cortex (PPC).

Which types of information are integrated by PPC?

Visual information, Somatosensory information, Vestibular information.

What does PPC transform sensory information into?

Movement plans.

Give an example of PPC function.

Seeing a cup → determining its location and orientation → generating a reaching plan.

What does the premotor cortex do with PPC output?

Converts sensory information into motor programs.

What does M1 do after PMA generates a motor program?

Executes the motor program.

Why are intracortical connections important?

Motor control requires communication between multiple cortical areas.

What are association fibres?

Connections within the same hemisphere.

Examples of association fibre connections?

PPC ↔ PMA, PMA ↔ M1, SMA ↔ M1.

Functions of association fibres?

Information integration, Movement planning.

What are commissural fibres?

Fibres connecting the two hemispheres.

Which structure contains the major commissural fibres?

Corpus callosum.

Function of commissural fibres?

Bilateral coordination.

What are projection fibres?

Connections between cortex and subcortical structures.

Which structures are connected by projection fibres?

Thalamus, Brainstem, Spinal cord, Basal ganglia, Cerebellum.

What is the function of the cortex–basal ganglia loop?

Movement selection and initiation.

Outline the cortex–basal ganglia loop.

Cortex ↓ Striatum ↓ Globus pallidus/Substantia nigra ↓ Thalamus ↓ Motor cortex.

Roles of the basal ganglia loop?

Facilitate desired movement, Suppress unwanted movement, Control movement vigour.

Clinical examples demonstrating basal ganglia function?

Parkinson's disease, Huntington's disease.

What is the function of the cortex–cerebellum loop?

Movement coordination and error correction.

Outline the cortex–cerebellum loop.

Motor cortex ↓ Pontine nuclei ↓ Cerebellum ↓ Deep cerebellar nuclei ↓ Thalamus ↓ Motor cortex.

Functions of the cortex–cerebellum loop?

Timing, Precision, Coordination, Motor learning, Error correction.

What does the cerebellum continuously compare?

Intended movement and actual movement.

What is the function of the brainstem–cerebellum loop?

Balance, posture and locomotion.

What are major inputs to the brainstem–cerebellum loop?

Vestibular nuclei, Reticular formation, Sensory systems.

What are major outputs of the brainstem–cerebellum loop?

Vestibulospinal pathways, Reticulospinal pathways.

Functions of the brainstem–cerebellum loop?

Balance, Eye movement control, Postural stability, Gait control.

Outline the sensory-motor sequence for reaching for a cup.

Visual cortex ↓ PPC identifies location ↓ PMA plans reach ↓ Basal ganglia facilitate movement ↓ M1 activates corticospinal tract ↓ Arm moves ↓ Visual + proprioceptive feedback ↓ Cerebellar correction ↓ Accurate grasp.

Outline the sensory-motor sequence for catching a ball.

V5/MT motion processing ↓ PPC calculates trajectory ↓ PMA prepares movement ↓ Basal ganglia initiate movement ↓ M1 executes movement ↓ Cerebellum updates trajectory ↓ Ball caught.

Which structures contribute to learning piano?

Prefrontal cortex, SMA, Basal ganglia, M1, Cerebellum.

Role of the prefrontal cortex during piano learning?

Goal formation.

Role of SMA during piano learning?

Sequence generation.

Role of basal ganglia during piano learning?

Motor program selection.

Role of M1 during piano learning?

Finger movement execution.

Role of the cerebellum during piano learning?

Timing and error correction.

What process improves performance during repeated piano practice?

Neuroplasticity.

What structures are required for goal-directed motor acts?

Prefrontal cortex, PPC, Premotor cortex, SMA, Basal ganglia, M1, Cerebellum, Brainstem, Spinal cord.

Which structure is responsible for goal formation?

Prefrontal cortex.

Which structure is responsible for sensorimotor integration?

Posterior parietal cortex.

Which structure is responsible for movement preparation?

Premotor cortex.

Which structure is responsible for movement sequencing?

SMA.

Which structure is responsible for movement selection and initiation?

Basal ganglia.

Which structure is responsible for movement execution?

M1.

Which structure is responsible for coordination and error correction?

Cerebellum.

Which structure is responsible for posture and balance?

Brainstem.

Which structure provides final motor output?

Spinal cord.

What are the three major motor control loops?

Cortex → Basal Ganglia → Thalamus → Cortex, Cortex → Cerebellum → Thalamus → Cortex, Brainstem ↔ Cerebellum.

What does the basal ganglia loop primarily control?

Movement selection and initiation.

What does the cerebellar loop primarily control?

Coordination, timing and motor learning.

What does the brainstem–cerebellum loop primarily control?

Balance, posture and locomotion.

Ultimate exam concept for goal-directed movement?

Goal-directed movement is a distributed process emerging from continuous interaction between sensory systems, association cortex, motor cortex, basal ganglia, cerebellum, brainstem and spinal cord through interconnected perception–action cycles.