Introduction to Neuroscience: Emotions, Aggression, and Stress

A comprehensive vocabulary review of Lecture 17 covering emotional concepts, neural circuits, pathways, clinical case studies, autonomic mechanisms, and emotional lateralization.

Emotions

Complex, short-lasting mental and physical reactions to an internal or external event (a trigger).

Feelings

Conscious, subjective perceptions and interpretations of an emotional state.

Moods

Longer-lasting, lower-intensity affective states that are not always tied to a specific trigger.

Six Core Emotions

The primary emotional states thought to be experienced universally by every individual: happiness (joy), sadness, fear, anger, disgust, and surprise.

Cognitive Appraisal

The cognitive process by which an individual evaluates and interprets a situation, event, or stimulus.

Limbic System

A network of interconnected brain structures—including the amygdala, hippocampus, hypothalamus, and cingulate gyrus—responsible for processing emotional stimuli and determining emotional significance.

Amygdala

A limbic structure in the temporal lobe responsible for detecting potential dangers and threats, triggering fear responses, facilitating emotional learning, and interpreting emotional stimuli.

"Low Road" Pathway

A rapid fear-processing pathway that routes sensory information directly from the thalamus to the amygdala, bypassing the cerebral cortex to permit immediate reactions to a threat.

"High Road" Pathway

A slower fear-processing pathway that directs sensory information from the thalamus through the sensory cortex before reaching the amygdala, allowing for conscious cognitive evaluation of the stimulus.

Patient S.M.

A clinical neurology patient with bilateral amygdala damage who demonstrated an inability to feel fear in response to threatening stimuli and difficulty identifying fear in facial expressions, though panic was still triggered by simulated suffocation through $CO_2$ inhalation.

Klüver-Bucy Syndrome

A neuropsychiatric condition caused by bilateral damage to the amygdala and hippocampus, characterized by an absence of fear and anger, unusual calmness, hyperorality, hypersexuality, hyperphagia, and visual object recognition deficits.

Orbitofrontal Cortex (OFC)

A prefrontal cortical region that acts as the final destination for emotional information before action, functioning to assign emotional value to stimuli, weigh rewards versus punishments, and regulate emotional impulses.

Phineas Gage

A railroad worker who survived an iron rod passing through his left frontal lobe, resulting in severe personality and behavioral alterations—such as impulsivity, profanity, poor social judgment, and lack of emotional regulation—despite intact intellectual capacity.

Decorticate Rage (Sham Rage)

Sudden, intense, and undirected rage evoked by mild stimuli in animals whose cerebral cortex has been removed or disconnected, providing evidence that cortical regions normally inhibit and regulate subcortical emotional responses.

Brainstem (in Emotion)

A subcortical structure responsible for coordinating physiological responses to emotion, including autonomic fight-or-flight reactions, alertness and wakefulness, basic defensive reflexes, and emotional expressions such as facial and vocal responses.

Locus Coeruleus (LC)

A small pontine nucleus that synthesizes the majority of the brain's norepinephrine, functioning to heighten arousal, alertness, and attention during threat or stress exposure.

Ventral Tegmental Area (VTA)

A midbrain dopaminergic nucleus that processes rewarding experiences, mediates reward-based learning, and motivates reward-seeking behavior.

Autonomic Nervous System (ANS)

A division of the peripheral nervous system responsible for involuntary physiological regulation to maintain homeostasis, split into the sympathetic (fight-or-flight; primary neurotransmitter norepinephrine) and parasympathetic (rest-or-digest; primary neurotransmitter acetylcholine) systems.

Facial Feedback Hypothesis

The proposition that sensory feedback from facial muscle movements directly influences emotional experience and subjective mood.

Bell's Palsy

A condition characterized by sudden unilateral facial muscle weakness or paralysis resulting from dysfunction of cranial nerve VII (facial nerve).

Moebius Syndrome

A congenital disorder characterized by the underdevelopment or complete absence of cranial nerves VI and VII, causing facial paralysis and an inability to produce facial expressions.

Emotional Lateralization

The asymmetrical distribution and processing of emotional recognition, expression, and regulation between the left and right cerebral hemispheres.

Left Frontal Lobe (in Emotion)

The frontal cortical region primarily associated with positive emotional processing and behavioral approach, including states such as joy, enthusiasm, and approach-related anger.

Right Frontal Lobe (in Emotion)

The frontal cortical region primarily associated with negative emotional processing and behavioral avoidance or withdrawal, such as fear, anxiety, and sadness.