midterm

Asomatagnosia

Loss of awareness or denial of ownership of a body part, often after parietal lobe damage.

Nociceptor

Specialized sensory receptor that detects tissue damage or potential damage (pain).

Analgesia

Reduced or absent pain.

Algesia

Sensitivity to pain.

Referred pain

Pain felt in a different location than its source (e.g., heart attack → arm pain).

Phantom pain

Pain perceived in a missing or amputated limb.

Dorsal column–medial lemniscus pathway (DCML)

Carries touch, vibration, and proprioception: receptors → spinal cord → medulla → thalamus (VP) → somatosensory cortex.

Mechanoreceptor

Receptor that responds to physical pressure or distortion (touch, vibration).

Pacinian corpuscle

Mechanoreceptor specialized for detecting deep pressure and vibration.

Dermatome

Skin area supplied by a single spinal nerve.

Shingles

Painful viral infection (reactivation of varicella virus) affecting specific dermatomes.

Neglect syndrome

Failure to attend to one side of the body/space (usually right parietal damage → neglect left side).

Periaqueductal gray (PAG)

Midbrain region that controls pain suppression via descending pathways.

Afferent pain gates

Incoming pain signals traveling from body → spinal cord → brain.

Descending pain gates

Brain pathways that inhibit/block pain signals at the spinal cord.

Endorphins

Natural opioids that reduce pain by binding opioid receptors.

Naloxone

Opioid antagonist that blocks endorphins/opioids, reversing analgesia/overdose.

Substance P

Neurotransmitter that transmits pain signals.

Capsaicin

Chemical in chili peppers that activates pain receptors (heat/burning sensation).

Histamine

Chemical released during injury/allergy causing inflammation & itching.

Bradykinin

Chemical that promotes inflammation and activates nociceptors.

Pain & placebo

Expectation of relief can reduce pain via brain mechanisms (endorphin release).

Melzack & Wall Gate Control Theory

Pain signals can be blocked or amplified in the spinal cord depending on competing input (e.g., rubbing reduces pain).

Topographic mapping

Spatial organization of sensory input in the brain (body mapped onto cortex).

Cortical map plasticity

Brain’s ability to reorganize sensory maps after injury or experience.

A-alpha

Fastest sensory axon class that is responsible for motor/proprioception.

A-beta

Sensory axon class responsible for touch.

A-delta

Sensory axon class responsible for fast sharp pain.

C fibers

Sensory axon class responsible for slow dull pain.

VP nucleus (ventral posterior nucleus)

Thalamic relay for body sensory info to the somatosensory cortex.

Warm-sensitive cells

Cells that respond to increases in temperature.

Cold-sensitive cells

Cells that respond to decreases in temperature.

Infrasound

Sound < 20 Hz (below human hearing).

Ultrasound

Sound > 20,000 Hz (above human hearing).

Middle ear ossicles

Malleus, incus, stapes—amplify sound vibrations.

Cochlea

Fluid-filled inner ear structure that converts sound into neural signals.

Basilar membrane

Vibrates at different locations depending on sound frequency.

Organ of Corti

Structure containing hair cells that transduce sound.

Inner hair cell

Primary sensory receptor for hearing, sending signals to the brain.

Spiral ganglion

Neuron cell bodies that carry auditory info to the brain.

Medial geniculate nucleus (MGN)

Thalamic relay for hearing to the auditory cortex.

Pheromones

Chemical signals released by one individual affecting behavior/physiology of others of the same species.

Set-point

Body’s regulated 'target' weight it tries to maintain.

Eating disorders

Disruptions in eating behavior (e.g., anorexia, bulimia, binge eating).

LH (lateral hypothalamus)

'Hunger center' that stimulates eating.

VMH (ventromedial hypothalamus)

'Satiety center' that stops eating.

Arcuate nucleus

Hypothalamic region integrating hunger signals.

Neuropeptide Y (NPY)

Strongly stimulates appetite.

Agouti-related protein (AgRP)

Increases hunger and food-seeking.

CART

Suppresses appetite.

Osmotic thirst

Triggered by cell dehydration (high salt concentration).

Antidiuretic hormone (ADH)

Reduces urine to conserve water.

Renin

Enzyme released by kidneys that starts a cascade to increase blood pressure.

Angiotensin

Stimulates thirst and vasoconstriction.

Aldosterone

Hormone that increases sodium retention (and water).

Subfornical organ (SFO)

Brain structure that detects blood osmolarity and triggers thirst.

Hyponatremia

Dangerously low sodium levels often from excess water intake.

Preoptic area (POA)

Hypothalamic region controlling body temperature and sleep initiation.

Narcolepsy

Disorder with sudden sleep attacks; linked to low hypocretin.

Circadian rhythms

~24-hour biological cycles (sleep, hormones, etc.).

Zeitgebers

External cues (light, food) that reset circadian rhythms.

SCN (suprachiasmatic nucleus)

Main biological clock in the hypothalamus.

Hypocretin / Orexin

Promotes wakefulness and stabilizes sleep-wake states.

Adenosine

Builds up during wakefulness to promote sleep pressure.

Desynchronized sleep (REM)

Active brain, dreaming, and muscle paralysis.

Synchronized sleep (NREM)

Slow-wave, deep sleep.

PGO waves

Brain waves during REM linked to dreaming and visual activity.

Purpose of dreams

Likely involved in memory processing, emotional regulation, and brain activity maintenance.

Sleep disorders

Conditions disrupting normal sleep.

Serotonin

Neurotransmitter involved in sleep regulation and mood.

Dopamine

Neurotransmitter involved in arousal and motivation.

Norepinephrine

Neurotransmitter involved in alertness.

GABA

Neurotransmitter that promotes sleep (inhibitory).

Acetylcholine

Neurotransmitter involved in REM sleep and wakefulness.