Neurotransmitters and Their Functions

Neurotransmitters

• Chemical messengers manufactured in the brain.
• Released from the axon terminal of a neuron into the synaptic cleft.
• Bind to receptors on the dendrites or cell body of the receiving neuron.
• Act like a lock and key, fitting into specific receptors based on their shape.
• Influence the receiving neuron to either fire or not fire.
• Play a role in cognitive abilities alongside hormones.

Acetylcholine

• Involved in learning and memory.
• Regulates heart muscle contractions, slowing it down when necessary.
• Plays a role in muscle control and movement.
• Reduced levels are associated with Alzheimer's disease.
• Botox inhibits its release, resulting in decreased muscle tension.

Dopamine

• Involved in learning, attention, movement, motivation, and reward.
• Increased levels are associated with pleasurable experiences.
• Plays a role in addiction, where it is hijacked to increase dopamine levels.
• Decreased levels are associated with Parkinson's disease.

Norepinephrine

• Influences eating habits, alertness, and wakefulness.
• Predominant in fear and the fight-or-flight response.
• Released during allergy reactions.
• Levels are low during sleep.

Glutamate

• Excitatory neurotransmitter involved in memory.
• Excess glutamate can lead to headaches and seizures.
• Avoiding MSG in the diet can help regulate glutamate levels.

Serotonin

• Plays a role in emotional states, sleep, impulsivity, aggression, and appetite.
• Low levels are linked to depression.
• Used to treat OCD and anxiety disorders by manipulating serotonin levels.

GABA

• Main inhibitory neurotransmitter.
• Controls anxiety.
• Found throughout the central nervous system.
• Activated by opiates (e.g., opium, morphine, heroin).
• Used for pain management in the medical field.

Endorphins

• Promote a natural sense of pleasure and enjoyment.
• Reduce pain.
• Released during physical activity, leading to the "runner's high."

Brain Hemispheres

• The brain has two hemispheres (left and right).
• The left hemisphere controls the right side of the body and vice versa.
• Left hemisphere: Language processing and speech.
• Right hemisphere: Visual and spatial tasks, nonverbal memory, and spatial awareness.

Frontal Lobes

• Located at the front of the brain and extend to the top center of the skull.
• Control voluntary body movement, speech production, thinking, motivation, planning, impulse control, and emotional responses.
• Damage to this area can affect personality and behavior, as seen in the case of Phineas Gage.

Motor Cortex

• Strip of tissue at the rear of the frontal lobes.
• Controls voluntary body movement.
• Studied by Wilder Penfield during brain surgery.
• Fine motor movements in hands and face have a larger representation in the motor cortex.

Somatosensory Cortex

• Located in the parietal lobes.
• Responsible for body awareness and spatial orientation.
• Tested in sobriety tests.
• Receives sensory information like temperature, touch, texture, and pain.
• Areas with greater sensitivity have larger representations in the somatosensory cortex (e.g., the mouth).

Occipital and Temporal Lobes

• Occipital Lobes: Primary visual cortex, responsible for interpreting visual information.
• Temporal Lobes: Primary auditory cortex, responsible for processing auditory information.
• Wernicke's Area (left lobe): Involved in interpreting auditory information.

Brain Waves

• Measured by an EEG (electroencephalograph).
• Reflect the electrical activity of the brain.
• Amplitude: Height of the wave.
• High amplitude, low frequency waves indicate low brain activity.

Scanning Techniques

• CT Scan: Uses rotating X-rays to create cross-sectional images of the brain. Reveals brain structure.
• MRI: Produces high-resolution images of brain structures using magnetic fields. Safe and does not expose patients to radiation. Reveals brain structure.
• fMRI: Functional MRI, measures changes in blood flow to determine brain activity.
• PET Scan: Functional scan that uses radioactive tracers to measure brain activity by monitoring glucose and oxygen consumption.

Key Points About the Nervous System

• Nervous System: Consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves throughout the body).
• Neuron: Basic unit of the nervous system, responsible for transmitting information.
• Synapse: Gap between two neurons where communication takes place.