Auditory System and Memory Processes

Vocabulary flashcards covering key terms and concepts from the lecture on the auditory system and memory processes.

Auditory System

Sensory system responsible for detecting, locating, and interpreting sound.

Sound

Mechanical energy transmitted as pressure waves through air.

Cycle

The distance between successive compressed regions of air in a sound wave.

Frequency (Hz)

Number of cycles per second; determines Pitch.

Intensity / Amplitude

Size of the sound wave; determines Loudness.

Outer Ear

Collects and funnels sound; includes the Pinna and Auditory Canal.

Tympanic Membrane

The eardrum; vibrates in response to sound waves.

Middle Ear Ossicles

Malleus, Incus, Stapes; amplify and transmit vibrations to the oval window.

Oval Window

Membrane that receives vibrations from the stapes and moves cochlear fluid.

Cochlea

Spiral-shaped, fluid-filled organ for sound conversion.

Basilar Membrane

Flexible membrane in the cochlea; critical for frequency detection.

Organ of Corti

Sits on the basilar membrane; contains the sensory hair cells.

Inner Hair Cells

Main sensory receptors transmitting info to the auditory nerve.

Outer Hair Cells

Amplifiers that enhance basilar membrane motion for quiet sounds.

Stereocilia

Hair-like projections that bend to trigger electrical signals.

Tectorial Membrane

The rigid membrane that stereocilia contact to trigger bending.

Endolymph vs. Perilymph

Endolymph: High $K^+$ (Scala Media). Perilymph: Low $K^+$ (Scala Vestibuli/Tympani).

Tonotopy

The spatial mapping of sound frequency along the basilar membrane.

Phase Locking

Neurons firing at a specific phase/point of a sound wave.

Volley Principle

Groups of neurons firing in turns to encode medium frequencies.

Superior Olive

Brainstem nucleus used for sound localization.

Short-Term Memory (STM)

Capacity to hold a small amount of info in an active state for ~30 seconds.

Working Memory

A subset of STM used for holding and manipulating info (e.g., mental math).

Long-Term Memory (LTM)

Large-capacity, durable storage of information over long periods.

Encoding

The process of integrating new information with existing knowledge.

Consolidation

The process of converting unstable STMs into stable LTMs.

Rehearsal

Repetition that maintains info in STM and aids the transfer to LTM.

Hebbian Learning

"Cells that fire together, wire together"; synaptic strengthening via co-activation.

Engram

The physical location or "trace" of a memory in the brain.

Plasticity

The ability of synapses to change in strength over time.

Explicit (Declarative) Memory

Memories for facts and events; requires conscious recall.

Implicit (Non-Declarative) Memory

Memories for skills, habits, and conditioning; unconscious recall.

Hippocampus

Essential for forming new explicit memories and consolidation.

Cortex

The site for permanent, long-term storage of explicit memories.

Striatum (Basal Ganglia)

Key structure for procedural memory and habit learning (e.g., riding a bike).

Amygdala

Interacts with the hippocampus to enhance emotional memory strength.

Anterograde Amnesia

Inability to form new memories after a brain injury.

Retrograde Amnesia

Loss of pre-existing memories from before a brain injury.

Patient H.M.

Famous case: Hippocampus removed; had severe anterograde amnesia but intact procedural memory.

Habituation

Decreased behavioral response to a repeated, non-threatening stimulus.

Sensitization

Increased response to a mild stimulus following a strong/noxious one.

Aplysia Model

Sea slug used to study the Gill Withdrawal Reflex and basic synaptic plasticity.

Ebbinghaus Curve

Shows rapid initial forgetting followed by a plateau; rehearsal reduces relearning time.

Limbic System

The brain’s "emotional headquarters"; includes the amygdala, hypothalamus, cingulate cortex, and PFC.

Basic Emotion Theory

Proposes that emotions (like joy or anger) are innate and universal across cultures.

Dimensional Theory

Proposes emotions are combinations of Arousal (intensity) and Valence (pleasantness).

Learned Fear

The amygdala supports conditioning by associating neutral stimuli with negative outcomes.

Serotonin

Modulates aggression; low levels are often associated with increased impulsive aggression.

Oxytocin

The "cuddle hormone"; essential for social bonding, trust, and maternal behavior.

Vasopressin

Primarily involved in pair bonding and social recognition.

Dopamine

Provides the reward signal associated with the "feeling" of love or achievement.

Phineas Gage

Famous case study: Damage to the PFC led to drastic personality changes and loss of emotional regulation.

Psychopathy

Often linked to reduced amygdala activity, leading to decreased empathy and fear recognition.

Emotional Decision Making

Personal/moral decisions engage emotional brain regions, while impersonal ones favor cognitive regions.

Synaptic Plasticity

The ability of synapses to change in strength based on activity and experience.

Long-Term Potentiation (LTP)

A lasting increase in synaptic strength following high-frequency stimulation.

AMPA Receptor

Glutamate receptor that allows $Na^+$ influx; responsible for initial depolarization.

NMDA Receptor

Coincidence detector; requires both Glutamate AND Depolarization to remove its $Mg^{2+}$ block.

$Ca^{2+}$ (Calcium)

The central signaling molecule; influx through NMDA receptors triggers the LTP cascade.

Early LTP

Short-term strengthening via phosphorylation and insertion of existing AMPA receptors.

Late LTP

Permanent strengthening requiring gene transcription (CREB) and new protein synthesis.

Long-Term Depression (LTD)

A long-lasting decrease in synaptic strength due to low-frequency stimulation.

Kinase

Enzyme that adds phosphate groups (phosphorylation) to strengthen synapses (LTP).

Phosphatase

Enzyme that removes phosphate groups to weaken synapses (LTD).

CREB

Transcription factor that regulates the genes needed for long-term memory consolidation.

Sleep Drive

The homeostatic need for sleep; driven by the accumulation of Adenosine during wakefulness.

VLPO

Hypothalamic "sleep switch" that uses GABA to inhibit arousal systems.

Orexin (Hypocretin)

Neurotransmitter that promotes wakefulness; lack of this leads to Narcolepsy.

EEG Waves

Theta (Stages 1–2; light sleep); Delta (Stages 3–4; deep/slow-wave sleep).

REM Sleep

Stage characterized by high brain activity, dreaming, and muscle paralysis.

SCN

The brain's "master clock" in the hypothalamus; regulated by light (Zeitgebers).

Synaptic Scaling

Occurs during sleep; strengthens relevant synapses while pruning/weakening irrelevant ones.

ASD (Autism)

Characterized by reduced synaptic pruning, leading to increased synapse density and hyper-excitability.

Alzheimer's Proteins

Amyloid-β (extracellular plaques) and Tau (intracellular neurofibrillary tangles).

Amyloid Cascade

Hypothesis that Aβ accumulation is the primary trigger for downstream neurodegeneration.

Schizophrenia

Involves excessive synaptic pruning and the Dopamine Hypothesis (overactive dopamine causing psychosis).

HPA Axis

Stress-response system (Hypothalamus-Pituitary-Adrenal); dysregulated in Anxiety and Depression.

Cortisol

The primary stress hormone released by the adrenal glands during HPA activation.

Monoamine Hypothesis

Suggests depression is caused by a deficiency in serotonin, dopamine, or norepinephrine.

BDNF

Protein linked to neuroplasticity; increased by fast-acting antidepressants like Ketamine.

Anxiety

Overactive Amygdala / Underactive Hippocampus.

Depression

Low Monoamines / Reduced Hippocampal Feedback.

Schizophrenia Treatment

Antipsychotics (Dopamine blockers).

Narcolepsy Treatment

Stimulants / Orexin agonists.