(Unit 3) Altering the Brain

Lecture 24-26

Central Nervous System

the brain and spinal cord

Peripheral Nervous System

the Ganglia (neuron bundles) outside the CNS, and all other nerves.

Neuron

The functional unit of the nervous system.

Dendrites

Branch-like structures that receive signals from other neurons.

Cell body

The part of the neuron that contains the nucleus.

Nucleus

The control center of the neuron containing genetic material.

Axon

The long, thin structure that transmits signals away from the cell body.

Synapse

The junction between two neurons where neurotransmitters are released.

Neurotransmitters

Chemicals released in response to an electrical impulse, passed between neurons.

Acetylcholine

neurotransmitter that controls skeletal muscles.

GABA

neurotransmitter that inhibits signaling.

Glutamate

neurotransmitter that stimulates signaling.

Dopamine

neurotransmitter that is heavily involved in the reward system.

Serotonin

neurotransmitter that regulates mood.

Spinal Cord

Surrounded by bony vertebrae; coordinates reflexes.

Brainstem

Has three sections: midbrain and hindbrain (pons and medulla); functions include homeostasis and coordination of movement.

Cerebellum

Part of the hindbrain; involved in coordination and learning motor skills.

Cerebrum

Part of the forebrain; processes sensory and motor information, decision making, and personality. Can be divided into 4 lobes

Temporal Lobe

process sensory information (smell, taste, sound), and stores memories

Frontal Lobe

controls thinking, planning, organizing, problem-solving, short-term memory and movement

Parietal Lobe

interprets feeling (sensory information), taste, texture, and temperature

Occipital Lobe

Responsible for vision.

Corpus Callosum

Bridges the two halves of the brain.

Primary Motor Cortex

Controls voluntary movements.

Cerebral cortex

Outer layer of the brain responsible for higher brain functions such as thought, memory, and sensory processing.

Primary Somatosensory Cortex

Processes sensory input from the body.

Somatic Nervous System

Controls skeletal muscle and external senses.

Autonomic Nervous System

Regulates involuntary bodily functions. Includes the sympathetic, parasympathetic, and enteric divisions of the brain

Sympathetic Division

Responsible for the fight or flight response.

Parasympathetic Division

Responsible for rest and digest functions.

Enteric Division

Controls the gastrointestinal system.

Psychoactive Drugs

Substances that alter a person's mood or behavior.

Drug Misuse

Using a drug for a purpose that is not indicated.

Drug Abuse

Excessive use of a substance.

Stimulants

Stimulate signaling in the brain.

Depressants

Inhibit signaling in the brain.

Hallucinogens/Psychedelics

Alter perception.

synergism

the activity of both drugs is heightened

antagonism

the combination inhibits each other's efficacy

inhibition

one drug prevents the activity of the other

intolerance

the combination produces unpleasant side effects (like nausea)

cross-tolerance

one drug causes tolerance to a different drug (not really inhibition, drives you to take more of the second drug)

alcohol

short term: relaxation, warmth, loss of fine motor control, balance, speech, vision, and hearing increasingly impaired, increasing loss of decision-making skills, nausea, loss of consciousness

long term: at a young age can damage the developing nervous system, light to moderate use reduces risk of heart disease, but heavy use leads to liver damage (called cirrhosis), risk for dependence on it

Marijuana

a naturally occurring stimulant derived from the buds of cannabis plants containing THC (Tetrahydrocannabinol)

marijuana (effects)

short term: intensifies stimuli, but reduces reaction time, can produce paranoia, increased appetite, and bloodshot eyes, occasionally can be used for medicinal purposes

long term: damages lungs and heart (similar to cigarettes)

Narcotics

also called opiates, derived from opium, a naturally occurring depressant in poppy flowers, sometimes used as pain killers

Amphetamines

a category of synthetic stimulants

methamphetamine (meth)

short term: Alertness

long term: Tolerance develops quickly, brain damage, increased risk for heart attack and stroke, can produce psychosis, paranoia, and aggression

Cocaine

The most powerful naturally occurring stimulant, a white powder derived from the coca plant, typically snorted

Crack

Freebase cocaine which is smoked

cocaine (effects)

short term: Energy and euphoria, increased heart rate and blood pressure, wears off quickly

long term: Users crash after usage, become quickly addicted, tolerance develops, results in mood disorders

Hallucinations

Alter a user's feelings, perceptions and thoughts, affecting the reticular formation in the brainstem

LSD (lysergic acid diethylamide)

common synthetic hallucinogen absorbed across the skin

LSD (effects)

short term: Introspection and insomnia

long term: There is no evidence of dependence

Mushrooms (psilocybin)

Natural hallucinogens that are ingested

mushrooms (effects)

Altered perceptions, usually visual, and nausea

MDMA/Methylene dioxymethamphetamine/Ecstasy

a synthetic stimulant and hallucinogen

Ecstasy (effects)

short term: Feelings of euphoria, love, and empathy; depression after use

long term: Damages the brain by killing serotonin-releasing cells

Addiction

Defined by a physical or psychological dependence on something, where stopping use causes symptoms of withdrawal

Symptoms of Addiction

Compulsion, loss of control, negative consequences, denial

How does addiction happen?

When substances provide pleasure, but as tolerance builds, more is required, leading to a lack of normalcy without the substance. Chemically, it messes with dopamine levels