neuro exam 2

Biological Rhythms

•  Regular, repeating fluctuations in any living process or bodily function.

Circadian Rhythms

• Daily patterns of behavioral, biochemical, or bodily fluctuations that repeat on a 24-hour cycle (such as hormone levels, body temperature, or drug sensitivity).

Diurnal vs. Nocturnal

• Diurnal means active during the day; nocturnal means active at night (both evolved historically for survival).

Mammalian Circadian Clock Period

• Mammals have an internal biological clock that naturally ticks on a cycle slightly longer than 24 hours.

Entrainment

• The process where something in our body’s internal cycle (like a heartbeat, brainwave, or sleep clock) synchronizes and aligns with an outside cue.

Zeitgeber

• Any naturally occurring outside time cue that resets and regulates the body's internal biological clock (the sun is the primary zeitgeber for our sleep rhythm).

Forebrain Sleep System

• A brain system that generates slow-wave sleep; stimulating it makes people sleepy, while removing it causes insomnia.

Brainstem Sleep System

• A brainstem network that activates the forebrain to promote wakefulness and alertness.

Pontine System

• A control area in the pons (part of the brainstem) that triggers dream sleep (REM sleep).

Hypothalamic Sleep System

A control center in the hypothalamus that coordinates and regulates the other three sleep systems

Hamster Wheel-Running Studies

•  In constant dim light with no outside time cues, hamsters kept the same daily running cycle, but it shifted slightly later each day because their built-in clock is naturally a bit longer than 24 hours.

SCN Hamster Removal Experiment

• Removing the SCN caused hamsters to completely lose their organized daily schedule, resulting in small, random bursts of activity and sleep scattered all through the day and night.

Suprachiasmatic Nucleus (SCN)

• A tiny area in the hypothalamus that serves as the body’s master internal biological clock.

SCN Transplant Experiment

• Taking SCN master clock cells from a donor hamster and implanting them into a host hamster causes the host to adopt the donor's personal cycle rhythm.

Retinohypothalamic Pathway

• A pathway in mammals that carries light information straight from the eye to the SCN via melanopsin

Melanopsin

• A light-sensitive photopigment found in certain eye cells that detects daylight without using rods and cones, triggering chemical events that reset the clock.

Melatonin

• A hormone released as night approaches; it informs the brain about day length to synchronize biological rhythms.

Exogenous Melatonin

Melatonin taken from the outside as a sleep treatment; it acts as a chronobiotic, shifting the internal body clock forward by about 30 to 60 minutes.

Two Broad Categories of Sleep

• Non-REM sleep (Stages 1, 2, and 3/slow-wave sleep) and REM sleep.

Nighttime Sleep Stage Progression

• We have more deep slow-wave sleep and less REM sleep at the beginning of the night, while later in the night we have more REM sleep and less slow-wave sleep.

Polysomnography

• A clinical sleep recording test that monitors brain waves, blood oxygen, heart rate, breathing, and eye and leg movements.

Stage 1 Sleep

• The lightest stage of sleep that happens right after falling asleep; marked on brain scans by alpha rhythms and sharper vertex waves.

Stage 2 Sleep

• A stage where muscles relax, body temperature drops, and breathing and heart rate slow; defined on brain scans by sleep spindles (sudden rapid wave bursts) and K-complexes (large spikes and sudden drop-offs).

Stage 2 Sleep Duration

•  We spend the majority of our sleeping time in this stage, making up about 50% of adult sleep.

Stage 3 / Slow-Wave Sleep (SWS)

• Deep, restorative recovery sleep marked on brain scans by delta waves (fewer full waves that dip low); vital for releasing growth hormone and cementing factual (declarative) memories.

Stage 4 REM (Paradoxical Sleep)

•  An active brain state with vivid dreams and moving eyes where brain waves look like waking, but the body stays completely still; occupies about 20% of sleep and lengthens toward morning.

Major Depressive Disorder (MDD) Sleep Sign

• Depression is linked to an elevated amount of REM sleep.

Motor Neuron Inhibition in REM

• the brainstem blocks voluntary movement during REM sleep by releasing GABA (a calming chemical), hyperpolarizing spinal motor neurons so muscles cannot move.

Nightmares vs. Night Terrors

Nightmares are long, scary dreams that wake people up from REM sleep; night terrors are sudden fright arousals from Stage 3 slow-wave sleep marked by panic and bodily agitation.

Dolphin Sleep (Unilateral Sleep)

• Dolphins lack REM sleep because body paralysis would drown them; instead, half of their brain sleeps in slow-wave sleep while the other half stays awake to surface and breathe, then they switch sides.

Infant Sleep

• Newborns require the most sleep and have much more REM sleep than adults; it takes them a few weeks after birth to establish a 24-hour rhythm because there are no daylight cues inside the womb.

Puberty Sleep Shift

• During puberty, the biological clock shifts later, causing teens to naturally fall asleep later and wake up later.

Aging and Slow-Wave Sleep

• Sleep quality drops in older age with more awakenings; slow-wave sleep drops by 50% by age 60 and completely disappears by age 90, coinciding with cognitive decline.

Four Biological Functions of Sleep

• (1) Energy conservation (lower heart rate, blood pressure, temperature, and breathing);

• (2) Ecological niche adaptation (staying hidden to avoid predators);

• (3) Brain and body restoration (secreting growth hormones and fighting infection);

• (4) Memory consolidation.

Glymphatic Cleaning

• Glial cells flush out toxic brain waste during sleep using cerebrospinal fluid.

Sleep and Memory Types

• Deep slow-wave sleep cements declarative (factual) memory, while REM sleep cements perceptual and skill learning (visual discrimination tasks).

Sleep Transformation of Memory

• Sleep actively reorganizes memory traces so the brain can extract new insights, draw inferences, combine abstract ideas, and spot emotionally significant details.

Night Half Memory Paradigm

• Testing memory after early sleep (rich in slow-wave sleep) produces better episodic/factual memory, while testing after late sleep (rich in REM) produces better procedural/skill memory.

Narcolepsy

• A disorder marked by frequent, intense daytime sleep attacks where a person skips slow-wave sleep and plunges straight into REM sleep.

Cataplexy

• A sudden loss of voluntary muscle tone causing physical collapse, often seen in narcolepsy.

Insomnia Treatments

• Treated medically with Z-drugs that boost GABA receptors (which carry a fast tolerance risk), or without drugs using Cognitive Behavioral Therapy (CBT) and light therapy.

Neuroendocrinology

• The scientific study of how the endocrine (hormone) system and the nervous (brain) system communicate and interact.

Hormone

• A chemical messenger secreted by an endocrine gland into the bloodstream that circulates through the body to regulate distant organs and tissues.

Endocrine Gland

• A bodily gland that releases chemical hormones directly into the bloodstream to act on distant targets.

Hormones vs. Neurotransmitters

•  Hormones travel through the bloodstream, act slowly over hours to months, and affect widespread body tissues at once; neurotransmitters release locally into microscopic synapses and act within milliseconds.

Peptide Hormones

• Water-soluble protein molecules that cannot pass through cell walls; they must bind to outer surface receptors and use second messengers to create rapid, short-term effects.

Steroid Hormones

•  Fat-soluble hormones that easily pass straight through cell membranes to bind inside cells; this hormone-receptor pair acts directly on DNA to produce slower, long-lasting physical changes.

Amine Hormones

• Simple hormones built from single amino acid building blocks, including norepinephrine and melatonin.

Hypothalamus

• A central brain region vital for bodily balance (homeostasis) that acts as the primary bridge linking the nervous system to the endocrine system.

Pituitary Gland

• The central hormone gland sitting at the base of the brain that serves as the bridge between the hypothalamus and the rest of the body.

Neuroendocrine Cell

• A hybrid brain cell that receives electrical signals from other neurons but responds by releasing hormones directly into the blood.

Homeostasis

• The biological maintenance of steady, stable internal body conditions despite changes in the outside world.

Negative Feedback Circuit

• The primary thermostat-like control system where high levels of an end hormone signal the brain and pituitary gland to turn down further hormone production.

Posterior Pituitary

• The back section of the pituitary gland that stores and releases two hypothalamic hormones—oxytocin and vasopressin—straight into the bloodstream.

• the posterior’s hormones are synthesized in hypothalamus, travel to posterior pituitary, then are spread into bloodstream

Oxytocin

• A hormone involved in social bonding, trust, maternal attachment, nursing, and birth contractions; it promotes bonding within your own group, but can increase outgroup mentality

Vasopressin

• A hormone essential for pair-bonding in males; blocking it stops male pair-bond formation, while injecting it triggers pair-bonding even without mating.

Anterior Pituitary 3-Step Chain

• secretes tropic hormones (FSH, LH, etc)

• (1) The hypothalamus makes and sends "releasing hormones" down a local bridge;

• (2) Releasing hormones tell the anterior pituitary to release "tropic hormones";

• (3) Tropic hormones travel through the blood to control glands throughout the body.

Three Human Endocrine Axes

• The Growth axis, the Hypothalamus-Pituitary-Adrenal (HPA) stress axis, and the Hypothalamus-Pituitary-Gonadal (HPG) reproductive axis.

Two Stages of Stress

• Stage 1 is an immediate physical emergency reaction;

• Stage 2 handles stress lasting past immediate moments by activating the HPA axis to release cortisol.

HPA Stress Axis Pathway

• The hypothalamus releases CRH, telling the anterior pituitary to secrete ACTH, which commands the adrenal glands on the kidneys to release cortisol into the blood.

Cortisol Effects & Risks

• Cortisol mobilizes energy similarly to sympathetic fight-or-flight activation (pupil dilation, elevated heart rate); however, excessive cortisol has toxic brain effects, hurting memory, stopping new neuron growth, and driving depression.

Cushing’s Syndrome

•  A condition caused by chronic excess cortisol, resulting in physical symptoms like a rounded "moon face," obesity, and bone thinning.

HPG Axis in Men

• The hypothalamus releases signals telling the anterior pituitary to secrete LH and FSH; in the testes, FSH helps make sperm while LH helps produce testosterone.

HPG Axis in Women

• The anterior pituitary sends FSH and LH to the ovaries; FSH helps ovarian follicles grow while LH triggers ovulation.

Testosterone and Human Aggression

•  Elevated testosterone is linked to social dominance and status rather than direct violence; testosterone levels naturally rise in winners and drop in losers after competitions.

Organizational Effect

• Exposure to male hormones (androgens/testosterone) during early, sensitive windows permanently organizes the physical wiring of the brain and external genitalia.

Congenital Adrenal Hyperplasia (CAH)

• A condition where developing female (XX) babies are exposed to excess adrenal androgens before birth, often resulting in intersex external genitalia.

Androgen Insensitivity Syndrome (AIS)

• A condition where a genetic male (XY) has testes and testosterone, but body cells lack androgen receptors, causing them to physically look, develop, and behave as women.

Puberty and the HPG Axis

• The reproductive axis is active during fetal development, goes quiet during childhood, and becomes highly active again at puberty to drive maturation.

Menstrual Cycle Brain Connectivity

• Brain scans reveal significant fluctuations in neural connectivity across the different phases of the monthly menstrual cycle.

Emotion

A subjective mental feeling state accompanied by distinctive cognition (how we think), behaviors (how we act), and physical body changes (heart rate, sweating).

Autonomic Balance in Emotion

• The body balances the sympathetic branch (fight-or-flight, preparing the body for action) and the parasympathetic branch (rest-and-digest) to maintain bodily balance.

Emotion vs. Feeling vs. Mood

• A feeling is a brief, immediate reaction; an emotion is a stronger feeling state that drives or stops motivated behavior; a mood is a diffuse, milder, and longer-lasting emotional background.

Circumplex Model of Emotion

•  A two-dimensional map plotting all emotional feelings along two lines: arousal (high energy vs. low energy) and valence (positive pleasure vs. negative distress).

Emotional Granularity

The ability to define emotions with rich detail; people develop greater granularity as they grow older rather than just feeling generally good or bad.

Common Sense (Basic) Theory of Emotion

• An outside stimulus makes you feel a mental emotion first, and that mental feeling then triggers physical body arousal.

James-Lange Theory

• An outside event triggers physical body changes first, and your conscious emotion is created by noticing those bodily sensations.

Cannon-Bard Theory

• An outside event triggers the conscious emotion and physical body changes at the exact same time.

Schachter-Singer Two-Factor Theory

• An event triggers a physical bodily reaction, and the brain then uses outside social and situational clues to cognitively label the cause, which decides which emotion you feel.

Classic Schachter-Singer Experiment

•  Men given adrenaline were either told the real bodily side effects, given wrong side effects, or told nothing. Those told nothing or given false information matched the mood of a confederate actor (acting playful or angry), showing that while bodily arousal intensifies feelings, cognitive labels determine which emotion we experience.

Theory of Constructed Emotion

• theory suggests that emotions are not hardwired or innate, but rather categories or concepts that the brain uses to make sense of the continuous stream of bodily sensations and stimuli

Interoception

The brain constantly sensing, monitoring, and predicting internal body states (like heartbeat, breathing, and stomach sensations).

Alexithymia

•  A condition where a person struggles to identify, name, and describe their own emotions, having limited emotional vocabulary beyond "good" or "bad" and focusing on outside events.

Eight Core Emotions

• universal facial expressions across cultures: anger, sadness, happiness, fear, disgust, surprise, contempt, and embarrassment.

Mouse Facial Expressions

High-speed cameras and artificial intelligence revealed that mice make distinct, measurable facial expressions for disgust, pleasure, pain, fear, sickness, and flight, evoking empathy signals in other mice.

Decorticate Rage

• Intense, uncontrolled rage seen in animals when the outer thinking cerebral cortex is surgically removed, showing that the cortex normally puts the brakes on deeper aggression circuits.

Klüver-Bucy Syndrome

•  A dramatic loss of fear and anxiety following surgical damage to the amygdala on both sides.

Prefrontal Lobotomy Side Effects

• Surgically severing prefrontal connections caused emotional flattening (blunting), loss of emotional depth, and poor impulse control, proving the prefrontal cortex is essential for expressing and regulating emotions.

Patient S.M.

• A woman with early bilateral amygdala damage who shows an absence of fear responses and cannot detect fearful facial expressions in others.

Emotional Salience Circuitry

•  A group of evolutionarily old, deep brain regions—the amygdala, insula, and anterior cingulate cortex—that spot and process vital threats and rewards.

Amygdala

• An almond-shaped subcortical structure that handles fear conditioning (linking warnings to bad outcomes), emotional memory, social threat evaluation, and reward motivation.

Anterior Cingulate Cortex (ACC)

• A medial brain region responsible for error detection, conflict monitoring, emotion regulation, motivational drive

Insula

• A deep brain structure serving as the bridge between body sensations and conscious feelings; it handles interoception (gut feelings), disgust, empathy, and bodily balance.

Prefrontal Cortex (PFC)

• An evolutionarily recent, expanded brain region responsible for higher-level cognitive executive functions, planning, and regulating emotional responses.

Emotion Regulation

 Conscious or unconscious processes used to start, stop, or change the direction and intensity of an emotional feeling.

Trigger for Emotion Regulation

• Regulation begins when the emotional reaction itself becomes the target of mental valuation (we notice our emotion and decide to change it).

Automatic Emotion Regulation

• Unconscious regulation driven by natural body systems (like the calming parasympathetic branch), including fear extinction and habituation.

Effortful Emotion Regulation

• Conscious mental strategies used to manage feelings; includes distraction, cognitive reappraisal, and emotional suppression (suppression is unhealthy; reappraisal is healthy and used in CBT).

Cognitive Reappraisal

Consciously thinking about an upsetting situation differently to change its emotional sting (such as reframing nervous stress as helpful excitement).

Lateral Prefrontal Cortex (lateral PFC)

• The side outer region of the front brain required for conscious emotion regulation, willpower, working memory, and goal-focused behavior.