Somatosensory & Other Senses Vocabulary

Flashcards of key vocabulary from the Somatosensory & Other Senses lecture.

Modalities of Sensory Systems

Touch, Pain, Hearing, Vestibular, Joint, Muscle, Vision, Thermal, Cold, Warmth, Chemical, Smell, Taste, Vomeronasal, Electrical, Electroreception, Magnetic, and Magnetoreception.

Receptor cell

A specialized cell that responds to stimuli in the internal or external environment, acting as filters and converting stimuli to electrical signals.

Labeled lines

Particular neurons that are labeled for distinctive sensory experiences from the outset.

Receptor potential

Electrical change in the receptor.

Sensory transduction

Conversion of environmental stimuli into action potentials.

Pacinian corpuscle

An onion-like structure in the innermost layer of the skin that responds to vibration and pressure.

Receptive field

Region of space in which a stimulus alters the neuron’s firing rate.

Sensory adaptation

Progressive decrease in a receptor’s response to sustained stimulation.

Phasic Receptors-definition

Frequency of action potentials drops rapidly as stimulation is maintained.

Tonic receptors

Frequency of action potentials declines slowly or not at all as stimulation is maintained.

Central Modulation of sensory information

Brain actively controls information it gets

Dermatome

Strip of skin that is innervated by a particular spinal dorsal root.

Primary sensory cortex

Initial destination of sensory inputs to the cortex.

Nonprimary sensory cortex

Collaborates with the primary cortices.

Primary somatosensory cortex (S1)

Located in the post central gyrus; gets info from the opposite side of the body.

Association areas

Process mix of inputs from different modalities.

Polymodal neurons

Allow different sensory systems to interact.

Synesthesia

A stimulus in one sensory modality evokes perception in another sensory modality.

Pain

Unpleasant sensory and emotional experience associated with actual and potential tissue damage.

Nociceptors

Free nerve endings specialized to detect damage.

Substance P

Peptide that selectively boosts pain signals and remodels pain pathway.

Neuropathic pain

Neurons continue to direct signal pain and amplify the pain signal in absence of tissue damage.

Gate Control Theory

Hypothesizes that spinal gates modulation sites at which pain can be facilitated or blocked which control the signal that gets to the brain.

Analgesia

Absence of pain

Naloxone

Opioid antagonist

Transcutaneous electrical nerve stimulation (TENS)

Mild electrical stimulation is applied to nerves around an injury to relieve pain.

Placebo effect

People believe they are getting a proven treatment.

Movements

Contractions of muscles that provide our sole means of interacting with the world around us.

Reflexes

Simple, unvarying and unlearned responses to sensory stimuli such as touch, pressure, and pain.

Motor plan

Complex set of commands to muscles is established before an act occurs.

Electromyography (EMG)

Electrical activity of muscles as they contract.

Antagonists

Muscles that counteracts effect of another

Synergist

Muscles that work together to move a limb

Motor Neurons

Transmits signal to motor nerves

Motor Unit

Motor neuron with all the muscle fibers it innervates

Proprioception

Collective information about body movements and positions.

Muscle spindle

Capsule buried amid other fibers of muscle that contains intrafusal fiber

Golgi tendon organs

Respond to tension as muscle shortens

Pyramidal System

Neuronal cell bodies within the frontal cortex & axons which pass through brainstem forming pyramidal tract

Extrapyramidal System

Axon pathways run from forebrain to brainstem & spinal cord and are outside the pyramids of the medulla

Primary Motor Cortex (M1)

Major source of pyramidal tract

Non-Primary Cortex Areas

Motor & premotor areas map behaviors rather than mapping specific movements in M1

Supplementary motor area (SMA)

Medial aspect of hemisphere for initiation of movement sequences

Premotor Cortex

Anterior to the primary motor cortex activated when motor sequences are guided by external events

Basal ganglia

Interconnected forebrain nuclei.

Ataxia

Decay of movement.

Parkinson’s Disease

Degeneration of dopamine-containing cells in substantia nigra

Huntington’s Disease

Excessive movement, Clumsiness, Twitches to face & fingers, Involuntary jerking

Pinnae

Outermost part of ear that funnels sound wave into ear canal

Cochlea

Coiled fluid-filled part of inner ear that converts vibrations from sounds to neural activity.

Organ of Corti

Converts vibration to neural activity

Hair Cells (Sterocilia)

Sensory cells-mini hairs

Basilar Membrane

Membrane that contains structures involved in auditory transduction

Tectorial Membrane

Blob atop organ of Corti

ICH afferents

Convey to the brain at potentials that provide the perception of sounds

OHC efferent

From the brain enable it to activate OHC to change length instantly; can modify stiffness of regions of the basilar membrane allowing for sharpened tuning and amplification

Place Coding Theory

Pitch of a sound is determined by the location of activated hair cels along the length of the basilar membrane

Temporal Coding Theory

Proposes that the frequency of a sound is encoded in the rate of firing of auditory nerves

Interaural intensity differences (IIDs)

Comparison of the intensity of the sounds

Interaural temporal differences (ITDs)

Differences between the time of arrival of sounds

Amusia

Inability to discern tunes or sing

Conduction Deafness

Fail to convert sounds vibrations within cochlea

Sensorineural Deafness

Fail to convert ripples created in basilar membrane into volleys of action potentials

Central Deafness

Auditory brain areas are damaged

Semicircular Canals

3 fluid-filled canals & 2 bulbs (saccule & utricle) allows head to move up/down, side to side, or tilting left/right

Ampulla

Chamber where hair cells embedded in gelatin mass are

Flavors

Variety of sensations aroused by food

Olfaction

Odor perception

Olfactory Epithelium

Lines part of nasal cavities Each olfactory receptor cell is a complete neuron