NEUR346 #21 Fa24

Lesson 21: Emotions and Motivated Behaviors

Page 1

• SYSTEMS NEUROBIOLOGY FALL 2024 Lesson 21 Emotions and Motivated Behaviors

Page 2: Objectives for Lesson 21

• Discuss the pyramidal and extrapyramidal contributions to emotional expression.

• Identify principal neuroanatomical structures of the limbic system and key inputs and outputs.

• Describe roles of the amygdala, nucleus accumbens/mesolimbic dopamine system, and hypothalamus in emotional responses and motivated behaviors.

• Understand the concept of hypothalamic-pituitary-target organ cascade.

• Describe emotional circuits and dysfunctions in clinical conditions such as affective disorders and addiction.

Page 3: Emotions

• Definition of Emotion: A complex psychological state involving a subjective experience, physiological response, and behavioral or expressive response.

• Evolutionary Utility: Emotions enhance survival by promoting adaptive behaviors.

• Generation of Emotions:

  • Physiological changes could lead to emotional perception.

  • Emotions may also trigger physiological responses.

• Neural Circuitry Involved: Anticipated circuits for emotional responses could include the limbic system and cortical processing.

• Facial Expressions: Connects with emotional expression through motor components.

Page 4: Components of Emotions

• Behavior: Observable response to emotions.

• Physiology: Bodily responses to emotions, such as heart rate increase.

• Emotion: Subjective feeling state.

• Feeling: Conscious experience of emotion.

Page 5: Emotional Circuits

• Inputs:

  • Sensory signals from sense organs, muscles, and internal organs.

  • Complex processing in the forebrain.

• Outputs:

  • Regulation of hormonal systems via the hypothalamus.

  • Activation of brainstem reticular formation.

  • Activation of somatic and autonomic motor systems.

Page 6: Expression of Emotional Experience

• Volitional Movement:

  • Pyramidal Projections: From limbic and motor cortex, fine control of movements.

• Emotional Expression:

  • Extrapyramidal Projections: Nonvolitional movements related to emotions.

  • Involvement of brainstem reticular formation and motor neuron pools.

Page 7: Emotional Expression

• Somatic Motor Processes:

  • Volitional: Controlled by pyramidal pathways from motor cortex to brainstem/spinal cord.

  • Nonvolitional: Controlled by extrapyramidal pathways from cingulate cortex via reticular formation.

Page 8: The Limbic System

• Key Structures:

  • Amygdala

  • Nucleus accumbens (ventral striatum)

  • Hypothalamus

  • Limbic cortex (cingulate gyrus, orbitofrontal cortex, prefrontal cortex)

  • Hippocampus

• Current Understanding: Shift from integrated emotional systems to functions of specific brain regions.

Page 9: The Amygdala

• Emotional Significance: Crucial for interpreting emotional context through converging sensory inputs.

• Emotional Behavior Expression: Outputs to hypothalamus and brainstem regulating emotional behaviors.

• Emotional Learning: Involvement in complex behaviors and reciprocal connections with limbic cortex, and other structures.

Page 10: Evidence for Role of Amygdala in Emotional/Fear

• S.M. Case Study:

  • Extensive amygdala damage resulted in lack of fear and inability to recognize fear in others.

  • Difficulty interpreting negative facial expressions.

Page 11: Emotional Experience and Decision Making

• Influence of Emotion on Behavior: Emotional context greatly affects social interactions and decision-making processes.

• Impact of Damage: Certain brain region damages can impair risk/benefit evaluation, affecting decision-making abilities such as those observed in affective disorders (depression, bipolar disorder, PTSD).

Page 12: Lateralization of Emotionality

• Language Prosody:

  • Right hemisphere responsible for expression and comprehension of emotional aspects of speech.

• Mood Asymmetry:

  • Left hemisphere linked to positive emotions; right hemisphere to negative emotions.

  • Dysfunction in the left hemisphere associated with depression.

Page 13: Internal Drives and Motivated Behaviors

• Necessary for Survival:

  • Hunger, thirst, thermoregulation, etc.

• Non-survival Drives:

  • Mating, exploration, social affiliation, aggression, pleasure-seeking.

Page 14: Motivated Behaviors

• Consummatory Behaviors:

  • Directly address needs (eating, drinking).

• Appetitive Behaviors:

  • Indirectly achieve goals; involve seeking and proceptive behaviors.

Page 15: Neural Mechanisms of Motivation (Slide 1 of 2)

• Brainstem and Spinal Cord: Execution of consummatory actions.

• Hypothalamus:

  • Integration of internal drives and sensory inputs.

  • Outputs influence autonomic functions in the brainstem.

Page 16: Neural Mechanisms of Motivation (Slide 2 of 2)

• Dopaminergic Pathways:

  • Nigrostriatal system: Activation of behaviors triggered by endogenous stimuli.

  • Mesolimbic system: Activation in response to learned incentives; changes in dopamine levels affect reward anticipation.

Page 17: Basal Ganglia Limbic Loop

• Nucleus Accumbens: Critical for reward motivation.

  • Inputs from limbic system, prefrontal cortex, and other brain structures.

  • Outputs to various brain areas associated with rewards and locomotion.

• Dysfunction: Linked to addiction, affective disorders, and other psychological conditions.

Page 18: Reward and Reinforcement

• Pleasure Centers: Identification through intracranial self-stimulation; involve areas like locus coeruleus and VTA.

Page 19: Ventral Striatal Circuits in Reward

• Reward stimuli elevate dopamine release in the nucleus accumbens, enhancing VTA neuron activity.

Page 20: Changes in Ventral Striatal Circuits in Addiction

• Addiction alters baseline dopamine and glutamate release, leading to compensatory receptor changes and tolerance development.

Page 21: Role of the Hypothalamus in Emotional Behavior Integration

• Regulates physiological states, neuroendocrine functions, and motivated behaviors.

Page 22: The HPA Axis

• Hormonal Cascade: Involved in stress response and energy homeostasis; involves multiple hormonal interactions across various organs.

Page 23: Actions of Glucocorticoids

• Physiological Effects: Enhance cardiovascular tone, regulate energy storage, and interact with other endocrine systems.

Page 24: End of Lesson 21

Page 25

• SYSTEMS NEUROBIOLOGY FALL 2024 Lesson 22 Learning and Memory

Page 26: Objectives for Lesson 22

• Distinguish between declarative, procedural, and emotional memory.

• Identify key structures and circuits in mediating different types of memory.

Page 27: Functional Categories of Memory

• Memory Types:

  • Working Memory

  • Long-term Memory (Declarative and Nondeclarative)

  • Declarative: Episodic (events) and Semantic (facts)

  • Nondeclarative: Priming, Skill Learning, Conditioning

Page 28: Functional Categories of Memory

• Conscious Accessibility:

  • Declarative memory is expressible in language; nondeclarative memory is not available in detail.

Page 29: Working Memory vs. Long-term Memory

• Working Memory:

  • Immediate recall, compromised by damage to the prefrontal cortex.

• Long-term Memory:

  • Hours to years, includes qualitative distinctions and relies on specific brain regions.

Page 30: Modulation of Memory

• Influencing Factors:

  • Priming effects, significance and associations, motivational states, and practice through repetition.

Page 31: Conditioned Learning

• Conditioning: Process of eliciting responses to stimuli through repeated pairing (classical and operant conditioning).

Page 32: Forgetting

• Normal Forgetting: Influenced by factors like time and significance; issues can arise as amnesia.

Page 33: Declarative Memory

• Components: Involves encoding, storage, and retrieval of facts/events, particularly linked to the hippocampus and associated areas.

Page 34: Storage of Declarative Memory

• Neocortex and Hippocampus: Projecting connections crucial for memory output and integration with cortical areas.

Page 35: Effects of Lesions on Declarative Memory

• Lesions: Impact memory retention; specific cases (H.M., N.A., R.B.) demonstrate varying deficits linked to damaged structures.

Page 36: Effects of Lesions on Declarative Memory

• Spatial Learning: Rodent models show that hippocampal damage impairs the ability to generalize from learned associations.

Page 37: Declarative vs. Nondeclarative Memory

• Acquisition and Storage Differences: Variation across memory types regarding sites of long-term storage.

Page 38: Procedural Memory

• Skill Acquisition: Involves the neostriatum and cerebellum, focusing on habits, skills, and adjustments in motor behaviors.

Page 39: Emotional Memory

• Key Aspects: Influenced by emotionally charged stimuli, independent of declarative memory; facilitated by the amygdala.

Page 40: Emotional Memory Circuits

• Anatomy: Involves pathways from sensory input to various regions, controlling neuroendocrine and autonomic responses.

Page 41: Emotional Memory

• Conditioned Fear: Requires specific pathways highlighting the importance of amygdala function over mere auditory cues.