Unit 8 Flashcards
(42 cards)
Emotion
is any relatively brief conscious experience characterized by intense mental activity and a high degree of pleasure or displeasure.
Valence, or hedonic tone
is the affective (mood-related) quality referring to the intrinsic attractiveness/”good”-ness (positive valence) or averseness/”bad”-ness (negative valence) of an event, object, or situation. The term also characterizes and categorizes specific emotions. For example, emotions popularly referred to as “negative”, such as anger and fear, have negative valence. Joy has positive valence. Positively valenced emotions are evoked by positively valenced events, objects, or situations. The term is also used to describe the hedonic tone of feelings, affect, certain behaviors (for example, approach and avoidance), goal attainment or nonattainment, and conformity with or violation of norms. Ambivalence can be viewed as conflict between positive and negative valence-carriers.
Feedback from facial muscles
Emotions correspond to universal qualities of associated facial expression, and making theses expressions produce corresponding body responses like change in heart rate and skin temp.
Neonatal imitation
We are pre wired to practice manipulating the muscles of emotional expressions based on the behavior of others.
Emotional Arousal
describes the level of physiological activity, which is independent of the valence of the emotion.
Schachter-Singer Theory, also known as the “two-factor theory” of emotion
states that 2 factors are needed to experience emotion. First, environmental stimuli elicits a physiological response. Second, we cognitively appraise this physiological activity, and try to give it the correct label.
Learned helplessness
is behavior exhibited by a subject after enduring repeated aversive stimuli beyond their control. It was initially thought to be caused from the subject’s acceptance of their powerlessness: discontinuing attempts to escape or avoid the aversive stimulus, even when such alternatives are unambiguously presented. Upon exhibiting such behavior, the subject was said to have acquired learned helplessness. Over the past few decades, neuroscience has provided insight into learned helplessness and shown that the original theory actually had it backwards: the brain’s default state is to assume that control is not present, and the presence of “helpfulness” is what is actually learned. If prefrontal cortex is removed, it won’t learn this.
Limbic system
is a set of brain structures located on both sides of the thalamus, immediately beneath the cerebrum and forming a border (=Latin ‘limbus’) around the brain stem. It is not a separate system but a collection of multiple structures. These structures are involved in the control of mood and attitude; are involved in storage of highly charged emotional memories; and in the control of appetite and sleep cycles.
The Papez circuit (or medial limbic circuit)
it’s one of the major neural circuit/pathway in the limbic system involved in the control of memory and emotional expression. It begins and ends with the hippocampus. Dysfunction of this circuit underlies temporal lobe epilepsy.
Hippocampus
Structure
Stretches from middle of brain (below corpus callosum) down into the temporal lobes, ending adjacent to the amygdala
Functions
Memory consolidation and retrieval
Spatial memories
Involved in emotion processing
Fornix (Latin: arch)
is a C-shaped bundle of nerve fibers in the brain that acts as the major output tract of the hippocampus. Has a role in modulating general cognition and episodic memory recall. Damage to the fornix can affect some aspects of memory.
Amygdala (plural: amygdalae; Latin: almond)
Structure
is one of two almond shaped groups of nuclei (groups of cell bodies) anterior to hippocampus in medial temporal lobes in complex vertebrates
Centromedial - autonomic functions
Basolateral - conscious/arousal processing
Function
Aggression, sex, stress
Fear conditioning
Memory consolidation
Role in learning to associate object with reward/punishment.
Centromedial nuclear group
Central nucleus is the major input to sympathetic nervous system; Stimulation causes smacking, salivation, licking and chewing movements, emptying of the bladder and rectum; increased food intake.
Basolateral nuclear group
Stimulation causes arousal, attention, reduced feeding; Strong stimulation causes powerful rage. Also has a role in conditioned fear (e.g., startle reflex)
Lateral Amygdala
Output to central gray area of midbrain; Part of tegmentum for motor control, esp. of neck muscles. Clenching these muscles helps protect fragile cervical neurons near surface during actions like the startle reflex. Output to hypothalamus (master hormone regulator) to influence autonomic nervous system responses like blood pressure and heart rate. Input from pain fibers/responses, sensory activity. Triggers startle reflex. Also involved in detecting and learning emotional associations with central and baso-lateral nuclei (info in the environment).
startle reflex
is a brainstem reflectory reaction (reflex) that serves to protect vulnerable parts, such as the back of the neck (whole-body startle) and the eyes (eyeblink) and facilitates escape from sudden stimuli. It is found across the lifespan of many species.
Post-traumatic stress disorder (PTSD)
an anxiety disorder in which patients have nightmares, flashbacks, increased arousal (sleeplessness, hypervigilance), depression, irritability, conditioned enhancement of startle reflex and avoidance of stimuli associated with a traumatic event such as war, rape, or assault. A new diagnosis of complex PTSD is now being used to describe PSTD symptoms that arise from an extended period of more mild/moderate stress, rather than from one very high stress event as is typically associated with PTSD.
Possible causes of PTSD
Alterations in baseline stress hormone levels (cortisol): initial differences in baseline cortisol levels may predispose individuals to PTSD
Anatomical/functional differences in amygdala, hippocampus, prefrontal cortex
Possibly maladaptive learning pathway to fear response through a hypersensitive, hyper-reactive and hyper-responsive hypothalamus-pituitary-adrenal axis [= major part of the neuroendocrine system that controls reactions to stress and regulates many body processes, including mood and emotion]
Cholecystokinin (CCK)
is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, also called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum, the first segment of the small intestine. CCK plays important physiological roles both as a neuropeptide in the central nervous system and as a peptide hormone in the gut. It participates in a number of processes such as digestion, satiety (fullness), and anxiety. CCK is found extensively throughout the central nervous system, with high concentrations found in the limbic system. In both humans and rodents, studies clearly indicate that elevated CCK levels cause increased anxiety. The site of the anxiety-inducing effects of CCK seems to be central with specific targets being the basolateral amygdala, hippocampus, hypothalamus, peraqueductal grey, and cortical regions.
CCK in amygdala
CCK stimulates post synaptic cell, opening Na+ gates (increasing activity)
Involved in learned enhancement of startle reflex
CCK in hypothalamus
CCK in hypothalamus suppresses hunger when blood sugar rises
Some diet pills are CCK agonists, that mimic CCK effects (activate CCK channels)
Side effect in amygdala = increased anxiety
CCK antagonists can block receptor sites, without opening gates
Has a calming effect but cause hunger (can promote over eating)
Serotonin (5-HT) in amygdala
Serotonin is released into post synaptic cell and once it’s bound it’s reuptaken whole into the pre synaptic cell
This breaks serotonin apart and creates a metabolic byproduct 5-HIAA
5-HIAA is disposed of into bloodstream by glial cells
Low lv of 5-HIAA in bloodstream creates impulsivity and depression (marker of low serotonin)
Anti depressants like PROSAC block serotonin reuptake by binding with the receptor, freeing available serotonin to re-stimulate the post synaptic cell (gives it more time to react with receptor and build up larger depolarization)
GABA in amygdala
GABA opens Cl- gates, inhibiting post synaptic cell (increased gaba = decreased activity and firing in amygdala) which helps to suppress startle reflex and reduces anxiety
Anti anxiety drugs like Valium are GABA agonists enables GABA to bind more easily and for longer to receptor site at post synaptic cell, increasing its effectiveness (larger signal)
Urbach–Wiethe disease
is a rare recessive genetic disorder that causes general thickening of the skin and mucous membranes. In some cases there is also a hardening of brain tissue in the medial temporal lobes, including calcification of the amygdala which impairs function. These amygdalar changes can cause impaired emotional responses, like a flattening of affect (limited mood range) and issues with interpreting emotions in other people.
