Biopsychology Class Notes PSY 1000 by Dr. Escobar PDF

PSY 1000 (Dr. Escobar) Chapter 3 Chapter 3 Biopsychology 3.1 H...

PSY 1000 (Dr. Escobar) Chapter 3 Chapter 3 Biopsychology 3.1 Human genetics 3.2 Cells of the nervous system 3.3 Parts of the nervous system 3.4 The brain and spinal cord 3.1 Human genetics 3.5 The endocrine system Why are psychologists interested in Genes and DNA genetics? Because understanding genetics allow us to better understand the Genes are hereditary units located in the cell’s biological factors that contribute to certain behaviors nucleus − Focus on individual differences that arise from the interaction of genes and Genes are made of DNA (deoxyribonucleic the environment acid) Related field: evolutionary psychology The information contained in the DNA − Focus on what universal patterns of behavior and cognition evolved over time determines how our genes work How do genes work? Genes or environment? Each gene contains information for the manufacturing of a given Genotype: Traits that an individual inherits (genes) protein Phenotype: Traits that an individual expresses (genes + environment) Thus, genes can affect our behavior through the synthesis of proteins Many years later Twins with a gene Healthy diet Unhealthy diet that predisposes them to obesity Same genotype Different phenotype 1 PSY 1000 (Dr. Escobar) Chapter 3 Chromosomes Gene transmission in sexual reproduction Genes group together in structures called All cells in the body divide constantly into two identical cells chromosomes The exception are sexual cells: They do NOT divide into two identical Humans have 23 pairs of chromosomes. The cells, but into four different cells 23rd pair determines sex − A parent female cell produces 4 eggs of which only one survives Some conditions result from chromosomal − A parent male cell produces 4 sperm, all of which survive abnormalities Degree of Relatedness Individual Organism Percentage of genes The process of meiosis shared with you an identical twin 100% Recombination = some of the first degree a sibling (brother or sister) 50 genetic material crosses over to a mother or father 50 the other chromosome a child 50 Recombination can occur at any second degree a grandparent 25 level of the chromosome = Each a grandchild 25 a half-brother or half-sister 25 sperm and egg are different from an aunt or uncle 25 each other a niece or nephew 25 Recombination Each sperm and egg have only 50% third degree a first cousin 12.5 of the parent’s genetic information a stepchild 0 or ? a spouse 0 or ? Zygote The joining of an egg and a sperm results in the formation of a zygote Identical or monozygotic twins Fraternal or dizygotic twins 2 PSY 1000 (Dr. Escobar) Chapter 3 Homozygous and heterozygous traits Dominant and recessive traits An allele is a version of a gene Recessive traits get expressed only if they are homozygous For each genomic location, we inherited one allele from our mother Dominant traits are expressed if they are homozygous or and one allele from our father heterozygous For each trait we can be either: − Homozygous: Identical alleles get paired. b b b B B B − Heterozygous: Different alleles get paired. Blue eyes Brown eyes Brown eyes Mendel’s laws Punnett square Brown eyes Brown eyes b B b B Parent 2 Bb B b B B b B B b b b B BB Bb Parent 1 Bb b Bb bb Brown= 75% Blue = 25% Mutations Mutations are sudden, permanent changes in a gene Most mutations are harmful, but some are beneficial − Example: Sickle cell anemia and resistance to malaria Online activity posted on Moodle Mutations and sexual reproduction (recombination) allow for genetic variability − Natural selection acts on variability − Organisms that are best adapted to the environment are more likely to survive and pass their genes on to the next generation 3 PSY 1000 (Dr. Escobar) Chapter 3 Gene-environment interactions Gene-environment interactions Range of reaction: Idea that our genes set the limits to our potential, Epigenetics: Experience may change our genetic material and environment determines how much of the potential is achieved − Example: Children of men with PTSD tend to have higher levels of anxiety − Example: Genes determine how smart you can be, a rich environment allows than children on men without PTSD you to express than intelligence Genetic-environmental interaction: Our genes influence our environment, and our environment influences the expression of our genes − Example: The child of a scientist is raised in an intellectually-rich environment. The parents’ genes create an environment that allows the child to express their genes Primary types of cells in the nervous system Neurons: Information processing Glial cells: Support cells for neurons. Glia have many functions: − Scaffolding and physical support 3.2 Cells of the nervous system − Insulation − Transport of nutrients − Processing of waste − Immune functions − Dispose of dead cells We seem to have as many glial cells as neurons Neurons Parts of the neuron Neurons are the basic building blocks of the nervous system Membrane: Semi-permeable, allows some molecules to pass into the We are born with ~100 billion neurons cell They are cells specialized in transmission of electrical signals Soma: Body of the cell. It contains the nucleus They have three main functions: reception, conduction, and Dendrites: Extensions of the soma, serve to receive inputs from other transmission neurons Axon: Long extension that can transmit electrical signals Terminal buttons: Extensions of the axon that can release neurotransmitters; they serve to send information to other neurons 4 PSY 1000 (Dr. Escobar) Chapter 3 How do neurons communicate? The membrane separates the fluid outside the cell from the fluid inside the cell (cytoplasm) When the neuron is not active, the membrane has negative charge = resting potential (the membrane is polarized) The resting potential The action potential When the neuron is polarized, there is more potassium than sodium When the cell is activated, “gates” open in the membrane and allow inside the cell sodium ions to enter the cell All ions move from areas of high concentration to areas of low This makes the membrane less negative (the membrane is concentration. Thus, sodium is attracted to the inside of the cell, depolarized) while potassium is attracted to the outside of the cell The refractory period When the membrane becomes depolarized, sodium gates close and potassium gates open Potassium rushes out of the cell, making the membrane hyperpolarized (even more negative) This is called a refractory period because even more stimulation is needed for the cell to have another action potential 5 PSY 1000 (Dr. Escobar) Chapter 3 Important facts about action potentials Action potentials start at the dendrites and end at the axon terminals A neuron’s firing is all-or-none: neurons cannot partially fire, and all action potentials have the same potency Watch short videos posted on Moodle How fast an action potential travels depends on the length of the neuron and whether the neuron is maximized for speed (range: 2-270 mph) Need for speed? Myelin! Glial cells cover some axons with a fatty substance known as the myelin sheath Myelin insulates the axons and can help make nerve conduction faster The myelin sheath has small gaps (nodes of Ranvier). Nerve impulses “skip” myelinated segments and “jump” from node to node making the signal travel faster Gray or white matter? Is myelin necessary? Myelinated areas (axons) appear white = white matter The myelin sheath provides a structure for re-connection of severed Areas that lack myelin (soma, dendrites, and axon terminals) appear axons (nerves) pink in live tissue and gray in dead tissue = gray matter This repair function only takes place in the peripheral nerves (not the central nervous system) Multiple sclerosis (MS): Disease damages myelin  scar tissue (sclerosis)  Disruption of nerve conduction 6 PSY 1000 (Dr. Escobar) Chapter 3 Synapses send messages to other neurons The synapse The communication between two neurons is called the synapse The cells that synapse do not touch each other (synaptic cleft) In a synapse, the axon terminals of one neuron send information to The axon terminals secrete biochemicals (neurotransmitters) that the dendrites of another neuron take the message across the gap to other neurons Neurotransmitters are taken by the receiving neuron at specialized sites known as receptors Each receptor is specific for a type of neurotransmitter (lock and key analogy) The synapse The synapse Neurotransmitters are stored in Synaptic activity ends when sack-like structures called there are no more vesicles neurotransmitters in the cleft The action potential causes Neurotransmitters can be vesicles to fuse with the destroyed (enzyme membrane and release the deactivation), or taken back by neurotransmitter into the the transmitting neuron synaptic cleft (reuptake and autoreception) Neurotransmitters Agonists and behavior Neurotransmitter action can be Drugs that increase or enhance altered in three primary ways: the action of a neurotransmitter 1. Production/release Increase production of 2. Availability at the cleft neurotransmitter 3. Binding to the receptor Block reuptake of neurotransmitter Mimic a neurotransmitter at receptor sites 7 PSY 1000 (Dr. Escobar) Chapter 3 Antagonists Drugs that decrease or inhibit the action of a neurotransmitter Decrease release of neurotransmitter Destroy neurotransmitter at synapse Block receptor sites Divisions of the nervous system 3.3 Parts of the nervous system Central nervous system Peripheral nervous system Brain and spinal cord All nerves that extend from the spinal cord to the periphery of the Protected inside bony structures body − Brain = skull Two divisions: − Spinal cord = vertebrae − Somatic: Collects sensory information (afferent) and reacts to that information (efferent) Extra protections: − Autonomic: Rest and activity functions − The CNS “floats” in fluid (cerebrospinal fluid or CSF). − Blood-brain barrier The autonomic nervous system is further divided into − Sympathetic: Stress-related activities (e.g., anxiety because of a quiz) − Parasympathetic: Routine activities (e.g., digestion) 8 PSY 1000 (Dr. Escobar) Chapter 3 3.4 The brain and spinal cord The spinal cord Communication highway Two main functions: The brain communicates with distal body − Axons conduct information to and parts using nerves that travel in the spinal from the brain from and to distal cord body parts These nerves form “columns” or − Acts like a “primitive brain” responsible for fast, life-saving “pathways” reflexes 30 segments, with nerves that exit through the spaces between vertebrae Gray matter Spinal reflexes (reflex arc) White matter Reflexes that can occur without involvement of the brain Sensory (afferent) A spinal reflex requires the activity of at least 3 neurons: − A sensory neuron that brings information from the senses − An interneuron to connect the sensory and motor neurons Spinal pathway (column) − A motor neuron that controls muscle activity Spinal nerves Motor (efferent) 9 PSY 1000 (Dr. Escobar) Chapter 3 Spinal cord lesions The brainstem The consequences of The brainstem connects the lesioning the spinal brain and spinal cord cord depend on the Made up of three structures: level at which the The medulla, midbrain, and lesion took place pons Sensation and motor It is responsible for basic control below the level survival functions, like of the lesion may be breathing and control of heart impaired rate Midbrain Credit: European Spinal Cord Injury Federation Pons Medulla The cerebellum The hindbrain and the midbrain The cerebellum (Latin: little brain) is located on the back of the head The cerebellum and brainstem make up the hindbrain, which is the Primarily, motor function: rapid, involuntary fine motor movement evolutionarily oldest part of the brain and voluntary movements that occur in rapid succession, motor Immediately around the hindbrain, we find the midbrain, which learning contains many important structures responsible for sleep/wake Cognitive functions: Planning, remembering cycles, regulation of mood, and experience of reward Emotional functions: Empathy Damage to the cerebellum = spinocerebellar degeneration (cerebellar ataxia) Subcortical The forebrain structures Largest part of the brain We are going to focus on: Composed of the cortex and some subcortical structures Hypothalamus Thalamus Amygdala Hippocampus 10 PSY 1000 (Dr. Escobar) Chapter 3 The hypothalamus: Master control The thalamus: Sensory gateway One of the most vital regions of the brain = connects to almost all All sensory information stops at the thalamus on the way to the brain brain regions Damage to the thalamus: loss of sensory capacity Master regulatory structure Olfaction (smell) is the only sense that skips the thalamus − Regulates vital functions (e.g., glucose level) and the behaviors that maintain them (e.g., hunger) − Controls pituitary gland (endocrine system) − Regulates function of internal organs − Sex differences in size The hippocampus: Memory formation The amygdala: Emotional center Fundamental to form long-term memories that are later stored Involved in fear responses and memory of fear elsewhere in the brain Can trigger defensive responses even before the stimulus enters Size of the hippocampus can change with memory challenges awareness Damage to the hippocampus: Difficulty or incapability of forming new Damage to the amygdala: Reduced capacity to show fear responses memories for facts The cerebral cortex Right hemisphere Left hemisphere The cortex is bigger than it appears! It is folded and convoluted (all its surface does not show) Unfolded, it would be about 6 ft2 The cortex can be divided into 2 hemispheres and 8 (4x2) lobes 11 PSY 1000 (Dr. Escobar) Chapter 3 The brain lobes The brain lobes Each lobe is represented Each lobe is associated in the left and right with a primary function hemisphere Somatosensory cortex The brain lobes Each lobe is associated with a primary function What about the rest of the brain? Contralateral control The rest of the brain serves to associate information processed by the The right side of the brain “feels” and “controls” the left side of the primary areas body and vice versa We do not really know why, but nerve fibers “cross” to the other side at the brainstem Most of our brain structures exist in duplicate (left and right) Our two hemispheres are joined by a bundle of axons (the corpus callosum) 12 PSY 1000 (Dr. Escobar) Chapter 3 Different hemispheres, different functions? Corpus callosotomy The left and right hemispheres are symmetrical with respect to their A treatment for extremely severe epilepsy is to section the corpus motor and sensory functions callosum This symmetry is NOT evident in the association areas This procedure reduces the frequency of seizures, and has no impact − The left hemisphere is more active than the right during language production on IQ, conversational abilities, or coordination of the two sides of the and comprehension body − The right hemisphere is more active than the left during nonverbal and But Some tests suggest that the two hemispheres of the brain were visuospatial analysis of information not communicating What if the two hemispheres did not communicate? Able to Unable to recognize by recognize by tact tact Ball Ball Watch the split-brain study video (Moodle) I don’t know what Ball! it says! Consequences of damage to the cortex Damage to the cortex = Loss of function. Which function depends on the area damaged Sometimes other areas of the brain take over the lost function = neuroplasticity Examples: − The case of Phineas Gage 3.5 The endocrine system − Wernicke’s aphasia − Broca’s aphasia − Hemineglect − Blindsight 13 PSY 1000 (Dr. Escobar) Chapter 3 The endocrine system produces hormones Major glands Hormones are similar to neurotransmitters because they are chemical Hormones are produced by glands, distributed throughout the body messengers that must bind to a receptor to send their signal The pituitary gland, which is connected to the hypothalamus, is the However, they differ from neurotrasmitters in that hormones master gland of the body (it controls all other glands in connection − Can impact receptors distally in the body with the hypothalamus) − Are slower than neurotransmitters in having an effect The thyroid gland regulates metabolism and appetite − Have effects that are longer-lasting than neurotransmitters’ The pineal gland regulates biological rhythms (e.g., sleep) The pancreas regulates blood sugar levels The gonads (ovaries, testes) modulate sexual behavior/characteristics 14