Lecture 33 Outline of Last Lecture I. The main olfactory system is responsible for detecting common odorantsa. Projects to olfactory bulb then pyriform cortex or amygdalaII. The accessory olfactory system is responsible for detecting pheromonesa. Projects to accessory olfactory bulb from vomeronasal organb. Extends to amygdala and hypothalamusc. Involved in reproductive and sociosexual behaviorsIII. There are five different receptor types giving rise to sweet, salty, sour, bitter, and umami taste sensationsa. Relayed from taste cells on the tongue to solitary tract b. Projections to insula or hypothalamus and orbitofrontal cortexIV. Innate releasing mechanisms are stereotypes actions that are induced by specific stimuliOutline of Current Lecture I. Regulatory behaviors are essential for survival and nonregulatory behaviors aid in other types of tasksII. The limbic circuit relies on the flow of information among several key structuresa. Hippocampus is important in memory function and learningb. Hypothalamus produces autonomic responses to external stimulic. Amygdala and frontal lobes are responsible for perceiving subjective feelingsIII. Seeking behaviors rely on the mesolimbic dopamine systema. Medial forebrain bundle projects dopaminergic neurons from the ventral tegmental area to the nucleus accumbensb. Dopamine is released in proportion to the motivation to self-stimulatec. Increased dopamine input to the nucleus accumbens is associated with pleasurable behaviors such as eating and sexCurrent Lecture- Regulatory behaviors maintain homeostasiso If compromised, death- Nonregulatory behaviors are not essential for survival- The hippocampus contains the mammilary nucleuso Relays information to the anterior hypothalamus to complete the limbic circuit Degenerated in alcoholism  major memory deficits o Very important in limbic system functiono Important in converting short term experiences into long term memories- Limbic circuit is important in memory and emotiono Emotion characteristics: Autonomic response  hypothalamusThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. NSCI 110 1st Edition Subjective feelings  amygdala and parts of the frontal lobe - Appraisal- Kluver and Bucy removed portions of the temporal lobe/amygdala, Rhesus monkeys were much more docile, exhibited hyperorality- Hypersexuality in humans when amygdala damages Cognition  cerebral cortexo James-Lange Theory states that we interpret autonomic changes as emotions Eliciting stimulus  autonomic arousal  conscious emotion Dependent on contexto Somatic Marker Hypothesis states that internal or external stimuli evoke emotionthat guides behavior and decision making Usually involves an unconscious biasREWARD- “Seeking behavior”- Olds and Milner (1950)  study showed that inserting an electrode into a rat’s brain caused them to self-administer electrical stimulation o Medial forebrain bundle (MFB) and lateral hypothalamus- Medial forebrain bundleo Dopaminergic tracts traveling from the ventral tegmental area to the nucleus accumbens (NAcc, associated with basal ganglia of the limbic system)o Ultimately connects to the brainstem  limbic systemo This constitutes the mesolimbic dopamine system (reward system)- Reward and dopamineo Dopamine is released in proportion to motivation to self-stimulateo Increased DA release to the NAcc in response to behaviors involving food, sex, nicotine, cocaine, sunbathing (all have some addictive effects) Viewing the stimulus even activates these areas - Reward may be separated into two distinct processeso Wanting  Seeking behavior, involves dopamineo Liking  Pleasure, involves opioids and GABA- Epigeneticso Experience alters gene expression in a way that can be long-lasting Doesn’t change the genes themselves, just rate of gene transcription These changes can be rapid and reversible, some may last a lifetime and can be passed on to subsequent generationso Chemical modifications can alter tightness of histones - Lasting effects of glutamateo Hippocampal neurons contain NMDA (blocked by magnesium ion) and AMPA receptors  Baseline activity increases only AMPA affinity when glutamate is released Increased activity depolarizes hippocampal neuron and magnesium ion leaves the pore- Calcium influx induced and may stimulate kinases that carry out metabolic activities inside cells- Influx may also increase the sensitivity of AMPA and NMDA receptors (increasing the number of these receptors) on the membrane- Forms a positive feedback loop and increases the size of the synapse So, the more you use a neural circuit (repeated actions), long-term retention is increasedo Experience alters the dendritic arbors and the dendritic spines (this is a long-term effect of