Key Concepts for Exam 2: Visual Pathways and Movement Control

Optic nerve

Transmits visual information from retina to brain.

Contralateral

Refers to opposite side processing in the brain.

Retinotopic maps

Neurons represent adjacent spatial areas in vision.

Lateral geniculate nucleus (LGN)

Processes visual information from both retinas.

Primary visual cortex (V1)

Initial cortical area for visual processing.

Ideal stimulus for V1 cells

Oriented lines or edges in visual field.

Where pathway

Processes spatial location; involves parietal lobe.

What pathway

Processes object recognition; involves temporal lobe.

Neurons in MT

Responsive to direction of motion in vision.

Akinetopsia

Loss of motion perception due to MT damage.

Neurons in V4

Responsive to color information in visual stimuli.

Achromatopsia

Loss of color perception due to V4 damage.

Neurons in IT

Responsive to complex visual objects and faces.

Prosopagnosia

Face blindness due to damage in FFA.

Motor unit

Single motor neuron and its muscle fibers.

Neuromuscular junction

Site where motor neuron stimulates muscle contraction.

Fast-Fatigable motor units

Generate quick, powerful contractions but fatigue quickly.

Fast Fatigue-Resistant motor units

Sustain activity longer than fast-fatigable units.

Slow motor units

Maintain posture; resistant to fatigue.

Local circuit neurons

Connect nearby motor neurons for coordinated movement.

Central pattern generators

Generate rhythmic locomotor behaviors through reflexes.

Cranial nuclei/nerves

Control head and neck movements; lower motor neurons.

Upper motor neurons

Control voluntary movements; located in brain.

Primary motor cortex (M1)

Initiates voluntary movement upon stimulation.

Corticospinal Tract

Pathway for complex voluntary movements.

Corticobulbar Tract

Controls facial and neck muscles.

Premotor Cortex

Involved in planning movements.

Mirror Neurons

Activate during observed and executed movements.

Cerebellum

Coordinates ongoing movement and balance.

Cerebellar Ataxia

Impaired balance, coordination, and movement precision.

Deep Cerebellar Nucleus

Processes motor commands and sensory feedback.

Efferent Copy

Copy of motor command sent to cerebellum.

Purkinje Cells

Inhibit deep cerebellar nuclei output.

Basal Ganglia

Regulates initiation and suppression of movement.

Direct Pathway

Excites movement via basal ganglia structures.

Indirect Pathway

Inhibits movement through basal ganglia structures.

Dopamine D1 Receptors

Excite neurons, enhancing movement initiation.

Dopamine D2 Receptors

Inhibit neurons, reducing movement initiation.

Parkinson's Disease

Loss of midbrain dopamine neurons causes motor issues.

Huntington's Disease

Genetic disorder causing uncontrolled movements.

Motor Stiffness

Rigidity and slowness in movement characteristic of Parkinson's.

Impulse Control Disorders

Side effect of Parkinson's treatment with dopamine.

Cerebellar Feedback

Adjusts movements based on expected vs. actual outcomes.

Vestibular System

Senses balance and spatial orientation.

Reticular Formation

Regulates arousal and motor control.

Autonomic Dysfunctions

Symptoms like constipation and low blood pressure in Parkinson's.

Dopamine

Neurotransmitter involved in reward signaling.

Taste Neuron Activation

Activated by direct or indirect signaling.

Labeled Line

Conveys specific taste information via ganglion cells.

Motivated Behavior

Actions driven by internal needs or desires.

Neurotransmitters

Produced in neurons, affect nearby cells.

Hormones

Produced in glands, released into bloodstream.

Ghrelin

Hormone released from stomach, stimulates hunger.

Leptin

Hormone from adipose tissue, decreases food intake.

GLP-1

Released from intestines, promotes weight loss.

AgRP/NPY Neurons

Promote hunger, inhibit energy expenditure.

POMC Neurons

Induce satiety, increase energy expenditure.

Cerebellum Function

Coordinates movement, balance, and posture.

Ataxia Symptoms

Impaired coordination and balance.

Purkinje Cells

Involved in motor coordination within cerebellum.

Direct Pathway

Facilitates movement via excitatory signals.

Indirect Pathway

Inhibits movement through complex signaling.

Substantia Nigra

Brain region critical for movement control.

Striatum

Integrates signals for motor control.

D1 Receptors

Excitatory dopamine receptors in the brain.

D2 Receptors

Inhibitory dopamine receptors in the brain.

Blood-Brain Barrier

Limits substance passage to protect the brain.

Second-Order Neurons

Regulate eating based on upstream neuron signals.