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Lecture 1b Final.docx

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PSYC 2800
Amanda Helleman

Lecture 1b *final+ • What Causes Emotional and Motivated Behavior? • Identifying the Causes of Behavior • Biology, Evolution, and Environment • Neuroanatomy of Motivated Behavior • Stimulating Emotion • Control of Regulatory Behavior • Control of Nonregulatory Behavior • Neuroanatomy of Motivated Behavior • Critical Structures – Hypothalamus and associated pituitary gland • Sends information to other brainstem circuits to produce behavior – Limbic system – Frontal lobes – Funnel metaphor • Hypothalamus critical in maintaining homeostasis – Process that maintains critical body functions within a narrow, fixed range – Body wants balance • Regulatory and Nonregulatory Behavior • Regulatory Behavior – Behavior motivated to meet the survival needs of the animal. Critical. – Controlled by homeostatic mechanisms (detecting mechanism), which involve the hypothalamus – Thermostat mechanism: Detects if temp drops and brings back to certain temp. – Examples: • Internal body temperature • Eating and drinking • Salt consumption • Waste elimination – Nonregulatory Behaviours • Behaviour unnecessary to meet the basic survival needs of the individual animal. • Not controlled by homeostatic mechanisms • Most involve the frontal lobes more than the hypothalamus. Newer behaviors (evolutionarily) as frontal lobes developed last. • Strongly influenced by external stimuli • Examples: – Sexual behavior, parental behavior, aggression, food preference, curiosity, and reading The Regulatory Function of the Hypothalamic Circuit • Hypothalamus maintains homeostasis by acting on the endocrine and autonomic nervous systems. Main structure for regulatory function maintenance. • Three regions of the hypothalamus important in maintaining homeostasis – Lateral Region – Medial Region rd – Paraventricular Region (surrounds 3 ventricle) • Lateral Hypothalamus • Contains nuclei and nerve tracts that connect the lower brainstem to the forebrain – Medial Forebrain Bundle (MFB) *tract+ • Tract that connects structures in the brainstem with various parts of the limbic system • Forms the activating projections form the brainstem to the basal ganglia and frontal cortex • Contains dopamine neurons • Dopamine-containing fibers are involved in reward and therefore contribute to many motivated behaviors • The Regulatory Function of the Hypothalamic Circuit • A principal function is to control the pituitary gland – Endocrine gland attached to the bottom of the hypothalamus – Associated with biological rhythms : ex: sleep/awake – Secretions control the activities of many other endocrine glands – Endocrine system consists of many glands, pituitary is one of them. Send signals to other glands to create hormones – Pituitary Gland • Posterior Pituitary – Neural tissue; continuation of the hypothalamus – Hormones released by axon terminals, carried by capillaries – Peptides released; enter bloodstream • E.g., oxytocin (critical for pairbonds, social bonding in humans). Released by women in labor, causes uterine contractions. Involved in breastfeeding. • Anterior Pituitary – Glandular tissue; synthesizes various hormones – Controlled by releasing hormones • Pituitary Gland • Releasing Hormones – Peptides that are released by the hypothalamus and act to increase or decrease the release of hormones from the anterior pituitary • E.g., prolactin controlled by prolactin-releasing factor. • The Regulatory Function of the Hypothalamic Circuit • Factors involved in controlling hypothalamic hormone-related activity – Feedback Loops • Control the amount of hormone that is released – Neural Regulation • Other brain regions (e.g., limbic system and frontal lobes) influence hormone release • Milk letdown, need oxytocin. Touch receptors in nipples send signals to higher brain regions to release oxytocin. Infant related stimuli also does this. • Anxiety decrease oxytocin release – Experiential Responses • Experience can alter the structure and function of hypothalamic neurons – E.g., oxytocin cells increase in breastfeeding women • The Regulatory Function of the Hypothalamic Circuit • Hypothalamus also is involved in generating behavior • Electrical stimulation of different nuclei in the hypothalamus will produce goal-directed behaviors, such as: – Eating and drinking – Digging – Displaying fear – Predatory or attack behavior – Reproductive behavior• Indistinguishable from normally occurring behaviours • Requires presence of eliciting stimuli • The Organizing Function of the Limbic Circuit • The primitive limbic cortex comprises: – Cingulate gyrus – Hippocampal formation • Hippocampus – Distinctive three-layered subcortical structure of the limbic system lying in the medial temporal region of the temporal lobe – Plays a role in species-specific behaviors, memory, and spatial navigation – Vulnerable to the effects of stress • Includes Parahippocampal cortex • Amygdala • Almond-shaped collection of nuclei located within the limbic system • Plays a role in emotional and species-specific behaviors • Receives input from all sensory systems – Many neurons respond to more than one sensory modality (multimodal) – Sensory stimuli elicits flashbacks in PTSD due to over activation of amygdala • Sends projections primarily to the hypothalamus and brainstem • The Executive Function of the Frontal Lobes • Three main regions – Motor Cortex • Controls fine movements – Premotor Cortex • Selection of appropriate movement sequences – Prefrontal Cortex: executive control, last to develop • Involved in specifying the goals toward which movement should be made • Dorsolateral and inferior regions • Receives connections from the amygdala, the dorsomedial thalamus, the posterior parietal (sensory association) cortex, and the dopaminergic cells of the ventral tegmental area – Dopaminergic input influences how prefrontal neurons react to stimuli, especially emotionally arousing stimuli – Engage in reward activities, this pathway activated. Teaching signal (about motivationally stimulating stimuli), important for survival – Also drug addiction • Outputs • Inferior region projects to the amygdala and the hypothalamus: Influences autonomic nervous system (HR, fight/flight, etc.) • Dorsolateral region projects to the posterior parietal cortex, the cingulate cortex, the basal ganglia, and the premotor cortex: Influences movement and memory • What is Emotion? • Difficult to describe/define – inferred internal state • Three components of emotion – Autonomic Response (e.g., increased heart rate) • Implicated structures: Hypothalamus and associated structures – Subjective Feelings (e.g., fear) • Amygdala and parts of frontal lobes – Cognitions (e.g., thoughts about the experience): Interpretation of autonomic response. • Cerebral cortex The Amygdala and Emotional Behavior • Involved in species-specific behaviors and emotion • Influences autonomic and hormonal responses via connections with the hypothalamus • Influences conscious awareness of the consequences of events and objects via connections with the prefrontal cortex. Ex: Fear & public speaking • Klüver-Bucy Syndrome: when lesion amygdala • Klüver-Bucy Syndrome • Behavioral syndrome, characterized especially by hypersexuality, that results from bilateral injury to the temporal lobe • Symptoms in monkeys – Tameness and loss of fear – Indiscriminate dietary behavior (eat ev – Greatly increased autoerotic, homosexual, and heterosexual activity with inappropriate object choice – Tendency to attend to and react to every visual stimulus – Tendency to examine all objects by mouth – Visual agnosia (inability to recognize objects) • The Prefrontal Cortex and Emotional Behavior • Damage to the prefrontal cortex has severe effects on social and emotional behavior – Inability to experience and express their own emotions and to recognize the emotional expression of others – Apathy and loss of initiative or drive – Inability to plan and organize, leading to poor decision-making – Can’t hold down jobs, bad at relationships, always late, etc. – Not respond to all stimuli in environment – Can’t assess consequences of behavior. – Control of Regulatory Behavior: Eating • Eating disorders entail being either overweight or underweight • Obesity or Binge-Eating Disorder – Excessive accumulation of body fat – Binge on high calorie amount in one sitting but don’t purge (as
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