Biopsychology Winter 2022 | Maya Varghese

      This week's reading was about psychological disorders, and focused on substance abuse disorders, mood disorders, schizophrenia, and autism. I've taken an abnormal psychology class at Foothill, but I found the reading was packed with a lot of information I had not come across before.     For each of the disorders, there was a section focused on genetics. Across all four, there's no definitive gene or set of genes that causes the condition. Instead, there may be multiple genetic pathways that intersect with environment to lead to the condition. In the case of substance abuse disorders, mood disorders, and schizophrenia, genetics only lead to a predisposition. Events throughout life, particularly stressful events, can lead to individuals with a predisposition developing the condition more easily than their non-predisposed peers. Autism is considered a neurological difference and lifelong condition, but it's not necessarily purely genetic. Prenatal environment, especi

    Regulating body temperature and making sure we eat and drink involves complex processes in which the brain tracks conditions inside the body and corrects imbalances. Sometimes this is handled without our being conscious of changes, but sometimes the brain triggers behaviors needed to maintain the body.      Homeostasis keeps body variables like temperatures within a fixed range or at a set point, by reacting to negative feedback. Allostasis is a similar concept, but works in anticipation of changes to prevent body variables from getting too far from the appropriate range. Temperature Mammals and birds are endothermic, meaning we generate our own heat. Basal metabolism, used to keep temperature constant, uses about ⅔ of a mammal’s energy, and is generated by brown adipose cells, which are a type of fat cell. For cooling, mammals use evaporation. This can be done through sweat, licking oneself, or panting. For heating, shivering, saving heat for internal organs, and fluffing fur add

  There are different definitions of emotion, but many include a cognitive aspect, a behavioral/physiological aspect, and feeling. Emotions can arouse both the sympathetic and parasympathetic branches of the nervous system, and most situations arouse parts of both. But a re these physical symptoms the result of an emotion, or is an emotion what we label a set of physical responses? The James-Lange theory suggests the latter. According to the theory, an event triggers an appraisal of the situation, followed by an appropriate action, including changes to physiology like increased heart rate. Then comes the emotional feeling. The principal idea of the James-Lange theory is that of cognition, behavior, and feeling, the feeling aspect is not first, but last of these three. Cognitions, behaviors, and feelings don’t always “stick” together. For example, you can have a cognition about a danger and take action without feeling much fear (getting a flu shot). And sometimes feelings are hard t

Brain Development, Damage, and Recovery      The developing brain starts as a neural tube surrounding a fluid cavity, when the embryo is at about 2 weeks. One end then starts to enlarge and differentiate into the hindbrain, midbrain, and forebrain. The midbrain and hindbrain start out as much larger proportions of the brain, and the forebrain grows and folds the most throughout later stages of embryo/fetus development.      Neurons mostly form in the first 28 weeks. Immunoglobulins and chemokines are chemicals that guide the neurons and glia when they migrate. After migrating the cell will differentiate into a neuron or glia. Neurons will develop dendrites and an axon. Axons then form synapses onto cells nearby. This process, of forming synapses, is a bit less precise than the migration. But while these synapses develop before birth, connections are strengthened, new ones will be added, and others pruned throughout an individual’s life (though it does slow as we age). Therefore, the co

Signals Across The Synapse While transmission of a signal along an axon is electrical, transmission between neurons is chemical. The chemicals used to signal are known as neurotransmitters, and the neuron synthesizes them in the axon terminals. Neurotransmitters There are about a hundred chemicals that are either confirmed or suspected neurotransmitters. Most fall into the following categories: Amino acids Modified amino acids/monoamines Includes serotonin, dopamine, norepinephrine, ephinephrine Neuropeptides, which are chains of amino acids Includes endorphins Purines Gases     Neurons make most neurotransmitters by modifying amino acids. For example, catecholamines, which includes dopamine, epinephrine, and norepinephrine, are made by attaching a catechol group to an amine group. These three all come from phenylanine. Serotonin comes from tryptophan (found in soy). We get these amino acids from our diet. Neurons keep supplies of neurotransmitters in the axon terminal after synthe

 The Cells of the Nervous System There are only two kinds of cells that make up the nervous system. Neurons are the ones we hear the most about, as they’re the ones that actually receive and transmit information. Glia perform many functions to support the nervous system’s work. Neurons There are a lot of neurons in our brains -- the average adult has 86 billion, plus another billion in the spinal cord. However, it varies from person to person. In addition to the organelles most cells have, like a nucleus, mitochondria, and ribosomes, neurons have unique structures. The main parts of a neuron are the: Soma: the main cell body, containing typical cell organelles Dendrites: branching fibers lined with synaptic receptors to receive information from other neurons Axon: a thin fiber which conveys an impulse. The impulse can be headed to other neurons, an organ, or a muscle. Axons can be very long -- we have axons that stretch from our spinal cords to our feet. The end of an axon has one