Even though psychology is a social science and defined as the study of the mind, the fields genetics and biology are also important. Specifically, we draw on these fields to understand the biological causes of behaviors and to understand the significance of brain functions and development. A big focus in this line of inquiry is the nature-nurture debate, namely whether our genes (nature) or our contexts and experiences (nurture) cause us to behave the way we do. Consequently, scientists differentiate between genotype (our genetic makeup) and phenotypes (inherited physical traits and characteristics).
It is generally recognized that genes do not exist in isolation -- that is, nature alone is not predictive of human behavior. Our genes provide the general structure (possible range for behaviors) in which we operate, but our inherited traits and our surroundings (nurture/environment) also contribute to those behaviors. So, our genes (nature) determines the possible range of a certain behavior (for example, artistic development) while our environment (nurture) determines its potential. For example, if a child has an innate talent for music (singing, playing an instrument) (gene) and is raised in a home in which parents provide ample opportunities and resources to foster a love for music, then this child will be more likely to reach her full potential of musical talent compared to a child who is not reared in such a fostering environment.
A nerve cell, or neuron, consists of a cell body, membrane, an axon covered in a myelin sheath, dendrites, and terminal buttons. Neurons rely on chemical messengers called neurotransmitters to communicate with one another; these neurotransmitters are stored in a neuron's terminal button. Once a neuron has been activated, an action potential fires,"activates" the neuron, and releases the neurotransmitter into the synaptic gap between neurons. When the receiving dendrites receive the signal, the receptors open and allow Na+ ions to move into the receiving cell. This causes the internal state of the receiving neuron to become positive. If that charge is strong enough to meet the threshold of excitation for the receiving neuron, it will become activated and start firing.
The central nervous system (CNS) consists of the brain and the spinal cord while the peripheral nervous system (PNS) is made up of the nerve cells throughout one's body. Essentially, the PNS connects the CNS to the rest of the body.
Neurons rely on chemical messengers called neurotransmitters to communicate with each other. These are stored in a neuron's terminal button. There are a number of neurotransmitters, each of which have different effects on behaviors. For example, dopamine and serotonin are associated with mood and sleep, while acetylcholine and glutamate are linked to memory. The release or inhibition of neurotransmitter release is associated with specific behaviors so if a neuron fires and releases acetylcholine, a person will have enhanced memory and cognition. However, when neurons are inhibited from releasing this neurotransmitter, the person will experience decreased memory.
Psychoactive drugs can impact neurotransmitters for example by forcing or inhibiting release of a neurotransmitter to regulate behavior. These are called agonist and antagonist responses, respectively. For example, patients experiencing schizophrenia symptoms have been found to have an overactive dopamine presence. Medications used to treat these patients consist primarily of dopamine antagonists to regulate this imbalance.
If brain functioning is impaired by an accident (damage to the head during a car accident, for example) or a stroke, researchers can draw upon brain imaging techniques to explore further. Strokes occurs when brain cells are deprived of oxygen and thus cannot function properly anymore.
Brain imaging techniques among patients with brain injuries can inform the field of neuropsychology greatly as we are still learning about specific brain structures and functions.
There are two methods involving radiation that allow researchers to study and take pictures of human brains. These techniques are particularly useful, as they are pain-free and not very invasive. They can provide ample evidence of brain functioning and damage following a stroke or an accident, for example. Computerized tomography (CT) is an x-ray of the brain. Magnetic resonance imaging (MRI) uses magnetic fields to image the brain.
The two hemispheres of our brain are connected with fibers. Some patients with severe epilepsy elect to separate those fibers through split-brain surgery, which disconnects both hemispheres in the hopes of stopping the spread of seizures. This surgery is often successful in taming epilepsy, but patients display a number of side effects. For example, they may be able to name an object but not be able to grasp it with their hand.
The endocrine system is made up of a number of glands that rely on chemical substances called hormones to communicate with each other and to regulate a number of behaviors such as metabolism, growth, sexual functions, sleep, reproduction, and mood. The pituitary gland is the master gland of the endocrine system; it regulates growth and pain hormones, among others. The thyroid gland is mostly responsible for regulating metabolism and appetite, while the pancreas secretes hormones that regulate sugar. Adrenal glands regulate stress hormones, and gonads secrete sexual hormones.
Unlike neurotransmitters, hormones travel through the body in the bloodstream. Hormones are typically slower to act, but tend to last longer than neurotransmitters. When hormones travel throughout the bloodstream, they must attach to their intended receptor cells for a message to be relayed. When a hormone binds to the correct cell, a biological process activates the receiving cell and corresponding gland. The major glands release hormones to regulate a number of functions, such as growth, appetite, sex, reproduction, and stress.
To review, see section 3.5 of the textbook.
Sleep is a daily period of time and state of consciousness during which the nervous system is relaxed and relatively inactive. Research concludes that sleep is essential to our everyday health and functioning; even a short time without sleep can be linked to changes in our mood, awareness, and overall psychological functioning.
Non-REM or NREM sleep has 4 stages. Stage 1 sleep is the transition from being awake to sleeping; stage 2 is deeper, more relaxing sleep; and stages 3 and 4 are deep sleep. Brain waves are different during each of these stages [how?]. REM sleep is characterized by rapid eye movements, but no muscle response; during REM sleep, brain waves show similar patterns to those while awake. Common sleep disorders include insomnia (the inability to fall or stay asleep), sleepwalking, sleep apnea (difficulty breathing during sleep), and narcolepsy (the tendency to fall asleep).
Sleep is an altered state of consciousness. Psychoactive drugs, such as prescription drugs or illegal substances, can also induce altered states. Drugs can impact our brain and behaviors in a number of ways and are categorized by their function. For example, alcohol, marijuana, and barbiturates have a sedative effect on the body and central nervous system. These substances are referred to as "depressants" because they slow the body and brain functioning down.
On the other hand, there are drugs that stimulate the brain and body resulting in increased activities. Stimulants such as cocaine and amphetamines increase dopamine activity and often result in increased body activity or feelings of pleasure.
Heroin and morphine are examples of opioids that have an analgesic effect on the body, and typically decrease pain sensations.
Hallucinogens such as LSD and PCP profoundly alter the users' perceptions and sensations, for example, by causing vivid hallucinations or strange and new body sensations (like ants crawling on one's skin).
This vocabulary list includes terms that might help you with the review items above and some terms you should be familiar with to be successful in completing the final exam for the course.
Try to think of the reason why each term is included.