Chapter 10 Emotional Learning and Memory

10.2 Brain Substrates

3 The Amygdala: A Central Processing Station for Emotions Encoding Emotional Contexts with the Hippocampus Feelings and the Frontal lobes Learning and Memory in Everyday Life— A Little Stress Is a Good Thing

4 Brain Structures Involved in Emotion Processing Papez (1937) sees that lesions cause emotional impairment; posits hippocampus, cingulate cortex, thalamus, and hypothalamus have role in emotion. Regions operate in loop—Papez circuit. Reasoning is starting point for later discoveries. e.g., amygdala’s role in emotion.

5 Brain Structures Involved in Emotion Processing Group of emotional brain structures known as limbic system. Emotions activate many brain regions (limbic system and beyond). Emotion = function of whole brain. Amygdala is critical.

6 The Amygdala: A Central Processing Station for Emotions Amygdala = 10 subregions (nuclei) with different inputs/outputs. Lateral nucleus = primary entry point for sensory information from thalamus and cortex to amygdala. Central nucleus sends info from amygdala to the ANS (physiological responses) and motor areas (behavioral responses). Basolateral nucleus sends info to cortex, basal ganglia and hippocampus to modulate memory storage and retrieval.

7 After LeDoux, 1998, 2000; McGaugh, Key Nuclei in Amygdala and Major Connections

8 The Amygdala and Learning of Emotional Responses In study: Amygdala stimulation elicits species-specific defensive reaction in animals. Elicits only vague feelings of foreboding in humans. Humans tend to interpret the context and then produce conscious feelings. Amygdala lesions in humans limit learning and display (expression) of new emotional responses.

9 Adapted from Bechara et al., Conditioning the Human Skin Conductance Response (SCR)

10 Two Pathways for Emotional Learning in the Amygdala 1. Direct thalamic-amygdala path for emergencies. Faster, less detailed Activates fight-or-flight 2. Indirect thalamic-cortical-amygdala path for mindful analysis. Slower, finer discrimination of stimulus detail Allows termination of fear response

11 Two Pathways for Emotional Learning in the Amygdala Learning CS–US association may take place in lateral nucleus of amygdala. Amygdala may guide storage of such fear- response memories (from direct or indirect path) and may even store certain details.

12 (a) Data from Rosenkranz and Grace, Lateral Amygdala and Conditioning

13 Stress Hormones and the Emotional Modulation of Memory Epinephrine stimulates the brainstem nuclei to produce norepinephrine… …which, in turn, stimulates the basolateral nucleus in amygdala to strengthen memory storage.

14 After McGaugh, 2002, One Way Amygdala Activation May Modulate Memory Storage

15 Encoding Emotional Contexts with the Hippocampus Hippocampal region contributes to encoding and retrieval of the learning context (environmental cues). In study: Patient with hippocampal lesion (HL) learned to respond to a colored shape as a cue for a loud noise, but could NOT remember. In contrast, patient with amygdala lesion (AL) could not learn the CR, but could remembere.

16 Conditioned Emotional Learning (a) Adapted from Phillips and LeDoux, 1992; (b, c) adapted from Bechara et al., 1995.

17 Feelings and the Frontal Lobes Frontal lobe, especially medial prefrontal cortex, facilitates: Interpretation of sensory input. Modulation of situational emotional reactions. Helps us appropriately interpret and respond to emotional stimuli. Adapted from Williams et al., 2001.

18 Learning and Memory in Everyday Life—A Little Stress Is a Good Thing Low levels of stress can improve memory. Mild stress leads to moderate arousal. Chronic high stress and arousal can impair encoding and recall. Stress hormones may overexcite hippocampus. Unclear how much stress is too much. Different people = different breaking points.

19 Yerkes-Dodson curve Describes Arousal–Learning Relationship

Interim Summary There is no single brain system for emotion; rather, many brain regions participate. Amygdala is the brain’s central processing station for emotions. Amygdala modulation of hippocampal and cortical storage may account for the strength of emotional memories.

Interim Summary Fight-or-flight is mediated by outputs from the central nucleus of the amygdala to the autonomic nervous system (ANS). ANS temporarily diverts resources toward bodily systems needed to fight or run away. Stimulating the amygdala can initiate a fight-or- flight response.

Interim Summary Lesions of the amygdala can lead to impairments in learned emotional responses. Frontal cortex may modulate or suppress expression (display) of emotion.

10.3 Clinical Perspectives

Clinical Perspectives Phobias Posttraumatic Stress Disorder

25 Negative Emotions, Stress, and Health Negative emotions and high stress can cause: Physical problems (e.g., high blood pressure, suppressed immune system) Psychological problems (anxiety disorders)

26 Phobias Phobia—overwhelming, irrational fear of an object, place, or situation. e.g., ophidiophobia (fear of snakes), agoraphobia (fear of open spaces). Best explained as arising through classical conditioning procedure. Michael Medford

27 Classical Conditioning and Phobias Stimulus in a phobia almost always something that was threatening to human ancestors. A biological predisposition to fear certain things. Not everyone who has a fear-evoking experience develops a phobia. Possibly developed through social transmission (e.g., fear of flying develops after reports of airplane crash).

28 Systematic Desensitization Systematic Desensitization—therapy for phobias; present successive approximations of CS while patient stays relaxed. Eventually CS no longer elicits reaction.

29 Systematic Desensitization Procedure: Phobic person learns to relax on cue (progressive relaxation). Present anxiety hierarchy—least fearful to most fearful contact with phobic object or event. Apply hierarchy sequentially while the phobic person remains relaxed; apply step gradually. Procedure can be slow but is generally successful and long-lasting.

30 Posttraumatic Stress Disorder Posttraumatic Stress Disorder (PTSD)— Obsessive thoughts, nightmares, or flashbacks persist long after exposure to the traumatic event. Trigger = many different stimuli reminiscent of original trauma. Individuals with PTSD fail to extinguish normal fear response. May involve overactive stress hormones.

31 Patterns of Psychological Recovery After Traumatic Event Adapted from Bonanno, 2005.

32 Posttraumatic Stress Disorder Physiologically: Cortical levels remain low and persistent. Epinephrine may increase without corresponding cortisol release, so fear response lasts longer. Possible drug treatment: Drugs like propanolol interfere with epinephrine, reducing stress reaction. With administration, may be less likely to develop PTSD.

33 PTSD and the Brain How to identify individuals at risk for PTSD? MRI studies indicates individuals with PTSD typically have smaller hippocampal volumes.

34 Hippocampal Volume and PTSD Adapted from Gilbertson et al., 2002.

Interim Summary Anxiety disorders may reflect fear responses gone awry. Phobias are excessive fears that interfere with daily life. In posttraumatic stress disorder, a natural fear reaction does not subside with time.