Psychophysics & Neural Activity - Vocabulary Flashcards

Vocabulary flashcards covering psychophysical methods, thresholds, scaling laws, and neuronal biology (neuron structure, glia, plasticity, and action potentials).

Psychophysical methods

Techniques to measure perception and thresholds, including adjustment, limits, constant stimuli, and signal detection theory.

Adjustment (self-tuning)

A fastest psychophysical method where subjects control stimulus intensity until it becomes detectable.

Limits (ascending/descending)

A psychophysical method using ordered yes/no trials to determine detection thresholds.

Constant stimuli

A psychophysical method with randomized intensities around a suspected threshold to reduce bias.

Signal detection theory

A framework that accounts for noise in perception and distinguishes hits, misses, false alarms, and correct rejections.

Absolute threshold

Minimum stimulus intensity needed to be detected about 50% of the time.

Audibility curve

Curve showing typical human hearing sensitivity, often best around 2–5 kHz.

Perimetry

Clinical tests that measure absolute thresholds across the visual field to detect defects.

Differential threshold (Just Noticeable Difference, JND)

Smallest detectable difference between two stimuli.

Weber’s Law

JNDs are proportional to the baseline intensity of the stimulus.

Weber fractions

Approximate ratios for JND relative to baseline: brightness ~0.08, loudness ~0.05, weight ~0.02.

Psychophysical scaling

Methods like magnitude estimation to relate perceived magnitude to stimulus intensity.

Fechner’s Law

Perception grows as the logarithm of stimulus intensity.

Stevens’ Power Law

A law that describes perceived magnitude with a power function, allowing compression or expansion.

Compression (in perception)

Perception grows more slowly than stimulus intensity (e.g., brightness).

Expansion (in perception)

Perception grows faster than stimulus intensity (e.g., pain, electric shock).

Neuron

A nerve cell that transmits electrical signals via soma, dendrites, axon, and terminals.

Soma (cell body)

The central part of a neuron containing the nucleus; integrates inputs.

Dendrites

Branching structures that receive input from other neurons.

Axon

Long fiber that conducts electrical impulses away from the soma.

Terminals

Endings of axons that release neurotransmitters to other neurons.

Myelin

Insulating sheath around axons that speeds conduction of nerve impulses.

Glial cells

Support cells that regulate the neural environment and signaling (e.g., astrocytes, oligodendrocytes, Schwann cells, microglia).

Astrocytes

Glial cells that regulate the neural environment and help recycle neurotransmitters.

Oligodendrocytes

CNS glial cells that form myelin around multiple axons.

Schwann cells

PNS glial cells that myelinate a single axon and aid regeneration.

Microglia

Glial immune cells that clear waste; chronic activation may be linked to neurodegenerative disease.

Neural plasticity

Brains’ ability to change in structure and function through learning and experience; greater in the PNS than CNS.

Wallerian degeneration

Degeneration of the distal axon segment after injury; can occur in the PNS with regeneration potential.

Nodes of Ranvier

Gaps in the myelin sheath that facilitate rapid saltatory conduction.

Action potential (AP)

All-or-none spike; Na+ influx depolarizes the neuron, K+ efflux repolarizes, followed by a refractory period.

Resting potential

Baseline membrane potential (~−70 mV) maintained by ion pumps and leak channels.

Na+/K+ ATPase

The sodium-potassium pump that restores ion gradients after an action potential.

Ion channels

Protein channels (e.g., Na+ and K+ voltage-gated) that open/close to regulate ionic flow during signaling.

All-or-none coding

Neural information is encoded by firing rate and pattern, not by the amplitude of spikes.