PSYC 210 Exam 4

Emotions

Neurobiological states that cause coordinated behavioral and cognitive responses triggered by the brain

Significant stimuli, thoughts, and memories can trigger neurobiological states

Emotions can trigger cognitive changes, hormone release, autonomic activation, and behavioral responses

Functions of emotions

Emotions help us survive, remember, cope, communicate, or motivate

Tell us important information and promote survival

They are adaptive

Limbic system

Set of regions that activate during and regulate emotion (especially fear), along with instinctual behavior, homeostasis, and memory

Patient S.M.

“Woman with no fear”

Had no amygdala and reported little to no fear

Did not learn from fearful experiences

Stood closer to people when talking

Alex Honnold

Famous free solo rock climber

Showed little amygdala activity when presented with frightening or disturbing images

Patient H.M.

Severe epilepsy lead to removal of his hippocampus, and damage to amygdala

Could not form new declarative memories

Fear conditioning was intact, but had no recollection of conditioning

Hypothalamic hamartoma

Tumors of the hypothalamus

Associated with aggression, rage attacks, reduced threshold for frustration, and extensive reactivity to minor stimuli

Phineas Gage

Iron rod went through his skull and damaged his prefrontal cortex (PFC)

After the accident, he was reported to be disinhibited and displayed gross, profane, and coarse behavior

Fear conditioning in rats

Emotion neural circuits

Low road: unconscious processing of threat

High road: conscious processing of threat

Hypothalamus, periacqueductal gray (PAG), and other regions involved in fear response

Lateral nucleus of amygdala: involved in fear learning

Central nucleus of amygdala: involved in regulating fear responses

Emotion regulation

System of top-down control that manages the intensity, duration, and expression of emotions

Cortex (especially PFC) projects to thalamus, sensory cortex, and amygdala to regulate emotions

Stress

Any circumstance that threatens or is perceived to threaten homeostasis

Can vary in duration, frequency, intensity

Stressor

An internal or external adverse force

Stress response

Coordinated physiological and behavioral reaction to homeostatic challenges

Stress appraisal

Cognitive process where individuals evaluate whether an event is threatening, harmful, or challenging, and determine their capacity to cope

Posits that interpretation of a stressor, rather than the event itself, dictates emotional and behavioral response

Thus, perceived intensity of stressor varies from person to person

Fear circuits

Low road: Sensory organ → thalamus → amygdala lateral nucleus → amygdala central nucleus → fear response

High road: Sensory organ → thalamus → Sensory cortex/hippocampus → amygdala lateral nucleus → amygdala central nucleus → fear response

Changes in arousal

Central amygdala (CeA) → Locus coeruleus (LC) → long range projections of norepinephrine to cortex, hippocampus → norepinephrine increases arousal

Changes in autonomic nervous system function

Central amygdala (CeA) → hypothalamus (lateral) → brainstem nuclei → spinal cord

Or CeA → brainstem nuclei → spinal cord

Increases heart rate, respiration, release of adrenaline

Adrenaline (epinephrine)

Hormone released in response to fearful stimulus by sympathetic nervous system

Circuit: spinal cord → adrenal gland → adrenal cortex → adrenal medulla → releases adrenaline

Increases heart rate, blood pressure, dilation of bronchioles in lungs, glucose release from liver, lypolysis (breakdown of fat), alertness

Hypothalamic-pituitary-adrenal (HPA) axis

Periventricular nuclei of hypothalamus (PVN) → Anterior pituitary via Corticotropin Releasing Hormone (CRH) → Adrenal cortex via Adrenocorticotropin Hormone (ACTH) → cortisol

Cortisol can act on the pituitary to inhibit ACTH via negative feedback loop

Effects of glucocorticoids

Brain: increases alertness, enhance memory consolidation

Metabolism: increases blood glucose, breakdown of protein, lipolysis

Cardiovascular: increases blood pressure

Immune: suppresses inflammation, inhibits immune response

Graph of adaptive responses to stress

Broad array of neurobiological endpoints show…