Neuroscience Overview

Neurotransmitters

• Serotonin: Regulates mood, appetite, and sleep.
• GABA (Gamma-Aminobutyric Acid): An inhibitory neurotransmitter that reduces neural activity.

Peripheral Nervous System (PNS)

• Comprises nerves and ganglia outside the brain and spinal cord, linking the CNS to the body.
• Divided into two main systems:
  • Somatic Nervous System (SNS): Controls voluntary movements, relaying signals between CNS and skeletal muscles.
  • Autonomic Nervous System (ANS): Regulates involuntary functions like heart rate and digestion, further divided into:
    • Sympathetic Nervous System: Activates "fight or flight" response, elevating heart rate and energy availability.
    • Parasympathetic Nervous System: Promotes "rest and digest" response, aiding energy conservation and digestion.
    • Enteric Nervous System: Controls gastrointestinal function.

Reflex Arc

• Simplest neural circuit enabling automatic reflex responses to stimuli.
• Processes reflex actions at the spinal cord, bypassing the brain for quicker reactions.
• Components include:
  • Sensory Receptor: Detects stimulus.
  • Sensory Neuron: Transmits impulse to spinal cord.
  • Interneuron: Processes information in the spinal cord.
  • Motor Neuron: Sends signal to effector to generate a response.

Microbial Environment in the Nervous System

• No normal flora is present in the nervous system; it remains sterile to prevent infections.
• Central nervous system protection includes the blood-brain barrier (BBB), controlling substance entry.

Symptoms of Neurological Infections

• Early Symptoms: Flu-like signs such as high fever, headache, chills, muscle aches, nausea, and diarrhea.
• Severe Symptoms:
  • Weil’s Disease: Causes liver failure and kidney damage.
  • Meningitis: Inflammation of protective membranes of the brain and spinal cord.
  • Respiratory Distress: Breathing difficulties.

Diagnosis and Treatment for Infections

• Diagnosis often involves blood tests.
• Antibiotics like doxycycline or penicillin are effective when started early.
• Preventive measures include avoiding contaminated water, wearing protective clothing, and controlling rodents.

Poliomyelitis (Polio)

• Infectious viral disease affecting the nervous system, potentially causing paralysis.
• Causative agent: Poliovirus from Enterovirus genus, with three serotypes: Type 1 (most prevalent), Type 2 (eradicated in 2015), and Type 3 (reduced incidence due to vaccination).
• Symptoms:
  • Asymptomatic cases are common.
  • Pain relief via over-the-counter medications like ibuprofen.

Shingles

• Caused by the reactivation of varicella-zoster virus (VZV), dormant after chickenpox.
• Reactivated by factors such as stress or immunosuppression, leading to localized skin symptoms.
• Treatment and Prevention:
  • Shingles vaccine recommended for adults aged 50 and older.
  • Good hygiene practices help reduce transmission risk.

Herpes Encephalitis

• Inflammation of the brain mainly caused by herpes simplex virus type 1 (HSV-1).
• Symptoms:
  • Early: Fever, headache, malaise.
  • Severe: Confusion, seizures, coordination loss, personality changes.
• Diagnosis: Clinical evaluation, MRI scans for brain inflammation, and CSF analysis.
• Treatment: Intravenous acyclovir and supportive care improve outcomes.

West Nile Virus Encephalopathy

• Caused by West Nile virus (WNV), primarily transmitted via mosquito bites.
• Signs and Symptoms: Mild flu-like symptoms, with severe cases leading to neurological complications.

African Sleeping Sickness

• Caused by Trypanosoma species transmitted by tsetse flies.
• Symptoms:
  • Early: Fever, headache, and joint pain.
  • Late: Behavioral changes, sleep disturbances, and Neurological complications.
• Diagnosis: Clinical evaluation and laboratory tests to identify parasites.
• Treatment: Antiparasitic medications vary by disease stage.

Cerebral Malaria

• Severe form of malaria affecting the brain and central nervous system.