Central Nervous System Overview

Central Nervous System (CNS)

• Comprises the brain and spinal cord, protected by three layers of meninges: dura mater, arachnoid mater, and pia mater.
• Dura mater is the thickest layer, providing protection and containing blood vessels.
• Arachnoid mater has a web-like structure, while pia mater is the soft layer directly covering the CNS.
• Cerebrospinal fluid (CSF) produced in the choroid plexus fills the space between the arachnoid and pia maters, cushioning the brain.
• CSF is produced continuously; blockage can lead to hydrocephalus, causing brain swelling and possible cognitive impairment.

Brain Structure

• The brain is housed in the cranial cavity and includes various components such as the cerebral cortex, limbic system, basal ganglia, thalamus, hypothalamus, and cerebellum.
• It can be sectioned sagittally (left to right), coronally (front to back), and horizontally (top to bottom) for analysis.

Cerebral Cortex

• Outer layer of the brain, composed of folded tissue (gyri and sulci) and separated into left and right hemispheres by a large sulcus.
• The corpus callosum connects both hemispheres, allowing information exchange.
• Functions of hemispheres are largely redundant; complete removal of one hemisphere can result in surprisingly few problems, especially in children.

Functional Lobes of the Brain

• Four main lobes: frontal, parietal, temporal, and occipital.
• Frontal lobe processes motor functions, cognitive controls like attention and decision-making, and houses the olfactory bulb.
• Parietal lobe processes touch sensations and spatial orientation and contains a somatosensory map similar to the motor cortex.
• Occipital lobe is primarily involved in visual processing.
• Temporal lobe processes sounds and includes the hippocampus, critical for memory formation.

Advanced Techniques in Brain Study

• Techniques for studying brain functions include examining brain injuries, transcranial magnetic stimulation (TMS), and functional magnetic resonance imaging (fMRI).
• Discoveries show that brain areas can serve multiple functions, reflecting its complex organization.

Basal Ganglia

• A group of interconnected brain structures involved in movement control, posture, and motivation.
• Damage can lead to conditions like Parkinson’s disease and changes in motivation, as seen in specific case studies.

Thalamus and Hypothalamus

• Thalamus acts as a sensory and motor input gateway, modulating awareness based on attention and arousal.
• Hypothalamus controls the endocrine system, regulating hormones affecting hunger, thirst, energy expenditure, and circadian rhythms.

Limbic System

• Regulatory system for emotions, encompassing key structures like the amygdala (involved in fear recognition) and parts of the cerebral cortex.
• Important for memory formation and emotional responses.

Cerebellum

• Located at the base of the brain, essential for balance and coordination of movements, including learning motor tasks.

Brainstem

• Connects brain’s upper regions to the spinal cord, regulating basic functions like breathing, heart rate, and alertness.
• Contains essential pathways for sensory and motor signal relay.

Spinal Cord

• Acts as a communication highway between the brain and body, surrounded by vertebrae and composed of white and gray matter.
• Gray matter contains neuron cell bodies; white matter consists of myelinated axons.
• Functions include conveying sensory information and controlling motor signals, as well as reflex actions, such as the knee jerk.

Spinal Cord Injuries

• Approximately 10,000 annual spinal cord injuries in the U.S. can lead to varying degrees of paralysis based on injury location.
• Research explores treatment options, including stem cell transplants and hypothermia induction to reduce inflammation post-injury.