The Brain: Structure and Function

The Brain

• The frontal lobe is responsible for social behavior, decision-making, emotions, and higher mental functions. Damage can lead to risk-taking/impulse issues, distraction, behavioral/emotional problems, and motor weakness.
• The parietal lobe processes sensory information, visuospatial processing, language, and mathematical skills. Damage results in impaired imagery, neglect of the left side, difficulties with reading, writing, and math.
• The occipital lobe houses the visual cortex. It receives visual information from the eyes and transmits it to the frontal lobe to help respond to what is seen. Damage causes hallucinations, homonymous hemianopias.
• The temporal lobe is associated with hearing, speech comprehension, memory, and perception/recognition. Damage leads to anterograde amnesia.
• The brain stem controls vital functions such as eye movement, hearing, speech, chewing, and swallowing.
• The cerebellum is responsible for motor control, balance, coordination, precision, and timing.

Grey vs White Matter

• Grey matter contains neuron somas and is mostly inside the CNS, typically in layers of cortex (brain).
• White matter contains myelinated axons and surrounds grey matter, like in the spinal cord.

ANS vs SNS

• The autonomic nervous system (ANS) regulates internal organs (smooth and cardiac muscles).
• The sympathetic nervous system (SNS) is part of the ANS and promotes increased activity for "fight or flight" situations (exercise, excitement, emergency, and embarrassment).
• The parasympathetic nervous system (PNS) is part of the ANS and promotes "rest and digesting" activities.

Neuron

• Neurons are nerve cells, and each contains: dendrites to receive signals, a nucleus controlling the cell, a soma organizing function, axons as the pathway for signals, and axon terminals that form junctions with other cells.
• Myelin sheaths speed up signal transmission, and nodes of Ranvier allow signal diffusion between them.
• Sensory neurons receive information from the environment, while motor neurons send commands to effectors (muscles/glands).

Motor Control

• Reflex Theory: Stimulus-response to create actions and behaviors.
• Hierarchical Theory: Cortical centers control top-down behavior in the nervous system.
• Motor Program Theory: Preprogrammed motor patterns in response to task demands, adaptive/flexible movements.
• Ecological Theory: Person/task/environment influences motor behavior and learning.
• Motor Programs: Prefabricated sets of commands in the central nervous system.
• Open Loop: Movement preprogrammed and executed without continuous sensory feedback.
• Closed Loop: Movement preprogrammed and executed with sensory feedback.
• Neurofacilitation: Therapeutic approach to facilitate normal movement patterns, inhibiting abnormal ones.

Neuroplasticity

• The brain's ability to modify itself in response to individual/task/environment influences, experiences, and injury.
• Repetition and intensity promote neural changes.
• Early intervention is crucial, as time is sensitive in this process.
• Synaptic connections strengthened by frequent use, weakening through disuse.
• Aerobic activity increases blood flow to the brain.
• Motor learning involves practice, feedback, skill acquisition, leading to permanent changes.
• Denervation supersensitivity increases receptor sensitivity.
• Neural regeneration can regrow axons, re-establish synapses, or form new strategies to compensate for damage.
• Cortical reorganization can involve more areas of the brain taking on lost functions.

Rules

• Use it or improve it.
• Specificity matters.
• Repetition matters.
• Intensity matters.
• Time matters.
• Salience matters (importance).
• Age matters.
• Transference.
• Interference.

Altered Movement and Sensation

• Volitional movement (intentional, purposeful actions) disruption can occur from neural impairment. Common causes include stroke, multiple sclerosis, Parkinson's disease, and traumatic brain injury (TBI).
• Sensation can be altered by heightening, reducing or eliminating sensory input; this also includes specific sensations like paresthesia, and allodynia.
• Damage to sensory pathways (spinal cord, brainstem, peripheral nerves, or cortex) can create these altered sensations.

Motor Control in Conditions

• Various conditions like stroke, multiple sclerosis, Parkinson's disease, and traumatic brain injury can impact motor control through differences in tone, rigidity, gait, postural instability, and freezing.

Postural Control

• Adaptation of posture for functional demands emphasizing balance, equilibrium, stability, and orientation (relationship between body and environment).

Sensory Systems

• Modalities: Visual, auditory, vestibular (balance), proprioceptive (body position awareness), somatosensory (touch, pressure, and temperature).
• CNS damage can affect perception in these sensory modalities.

Neural and Non-Neural Impairment

• Neural impairments include CNS and PNS damage, impacting motor control and sensation.
• Non-neural impairments include musculoskeletal (fractures, tendinopathies), cardiovascular/pulmonary (COPD, heart failure, PAD).
• Other systemic impairments like diabetes, obesity, and cancer can also impact function.

Other Specific Topics

• Parkinson's : Progressive loss of dopaminergic neurons in the substantia nigra.

• Multiple Sclerosis : Progressive, degenerative disease affecting the central nervous system, characterized by demyelination of nerves.

• Stroke : Cerebrovascular accident disrupting blood flow to the brain..

• Traumatic Brain Injury : Injury resulting from head trauma categorized as acquired or traumatic.