8 - General Principles of Sensory Processing, Touch, and Pain Flashcards
Stimulus
A physical event that triggers a sensory response
Sensory receptor organ
An organ (such as an eye or ear) specialized to receive particular stimuli
Receptor cell
A specialized cell that responds to a particular energy or substance in the internal or external environment, and converts this energy into a change in the electrical potential across its membrane
Adequate stimulus
The type of stimulus for which a given sensory organ is particularly adapted
Specific nerve energies
The doctrine that the receptors and neural channels for the different senses are independent and operate in their own separate ways, and can produce only one particular sensation each
Labeled lines
The concept that each nerve input to the brain reports only to a particular type of information
Sensory transduction
The process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane
Generator potential
A local change in the resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of action potentials
Pacinian corpuscle
A skin receptor cell type that detects vibration
Threshold
The stimulus intensity that is just adequate to trigger an action potential at the axon hillock
Coding
The rules by which action potentials in a sensory system reflect a physical stimulus
Range fractionation
A hypothesis of stimulus intensity perception stating that a wide range of intensity values can be encoded by a group of cells, each of which is a specialist for a particular range of stimulus intensities
Somatosensory
Referring to the body sensation, particularly touch and pain sensation
Adaptation
The progressive loss of receptor sensitivity as stimulation is maintained
Tonic receptor
A receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained
Phasic receptor
A receptor in which the frequency of action potentials drops rapidly as stimulation is maintained
Central modulation of sensory information
The process in which higher brain centers, such as the cortex and thalamus, suppress some sources of sensory information and amplify others
Sensory pathway
The chain of neural connections from sensory receptor cells to the cortex
Thalamus
The brain regions at the top of the brainstem that trade information with the cortex
Receptive field
The stimulus region and features that affect the activity of a cell in a sensory system
Primary sensory cortex
For a given sensory modality, the region of cortex that receives most of the information about that modality from the thalamus or, in the case of olfaction, directly from the secondary sensory neurons
Secondary sensory cortex or nonprimary sensory cortex
For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality
Primary somatosensory cortex (S1) or somatosensory 1
The gyrus just posterior to the central sulcus where sensory receptors on the body surface are mapped. Primary cortex for receiving touch and pain information; in the parietal lobe
Secondary somatosensory cortex (S2) or somatosensory 2
The region of cortex that receives direct projections from primary somatosensory cortex
Attention
A state or condition of selective awareness or perceptual receptivity, by which specific stimuli are selected for enhanced processing
Polymodal
Involving several sensory modalities
Synesthesia
A condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality
Epidermis
The outermost layer of skin, over the dermis
Dermis
The middle layer of skin, between the epidermis and the hypodermis
Hypodermis
Also called subcutaneous tissue. The innermost layer of skin, under the dermis
Tactile
Of or relating to touch
Meissner’s corpuscle
A skin receptor cell type that detects light touch
Merkel’s disc
A skin receptor cell type that detects light touch
Dorsal column system
A somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain
Dermatome
A strip of skin innervated by a particular spinal root
Ruffini’s ending
A skin receptor cell type that detects stretching of the skin
Pain
The discomfort normally associated with tissue damage
Congenital insensitivity to pain
The condition of being born without the ability to perceive pain
Nociceptor
A receptor that responds to stimuli that produce tissue damage or pose the threat of damage
Free nerve ending
An axon that terminates in the skin without any specialized cell associated with it and that detects pain and/or changes in temperature
Capsaicin
A compound synthesized by various plants to deter predators by mimicking the experience of burning
Transient receptor potential vanilloid type 1 (TRPV1)
Also called vanilloid receptor 1. A receptor that binds capsaicin to transmit the burning sensation from chili peppers and normally detects sudden increases in temperature
Transient receptor potential 2 (TRP2)
A receptor, found in some free nerve endings, that opens its channel in response to rising temperatures
A delta (Aß) fiber
A moderately large, myelinated, and therefore fast-conducting, axon, usually transmitting pain information
C fiber
A small, unmyelinated axon that conducts pain information slowly and adapts slowly
Cool-menthol receptor 1 (CMR1)
Also called TRP8. A sensory receptor, found in some free nerve endings, that opens an ion channel in response to a mild temperature drop or exposure to menthol
Gastrin-releasing peptide (GRP)
A neuropeptide that stimulates neurons in the dorsal horn to provide the sensation of an itch
Anterolateral system or spinothalamic system
A somatosensory system that carries most of the pain information from the body to the brain
Glutamate
An amino acid transmitter, the most common excitatory transmitter
Substance P
A peptide transmitter implicated in pain transmission
Neuropathic pain
Pain caused by damage to peripheral nerves; often difficult to treat
Cingulate cortex
Also called cingulum. A region of medial cerebral cortex that lies dorsal to the corpus callosum
Analgesia
Absence of or reduction in pain
Opiates
A class of compounds that exert an effect like that of opium, including reduced pain sensitivity
Opioids
A class of peptides produced in various regions of the brain that bind to opioid receptors and act like opiates
Endogenous opioids
A family of peptide transmitters that have been called the body’s own narcotics. The three kinds are enkephalins, endorphins, and dynorphins
Endorphins
One of three kinds of endogenous opioids
Enkephalins
One of three kinds of endogenous opioids
Dynorphins
One of three kinds of endogenous opioids
Opioid receptor
A receptor that responds to endogenous and/or exogenous opioids
Periaqueductal gray
The neuronal body-rich region of the midbrain surrounding the cerebral aqueduct that connects the third and fourth ventricles; involved in pain perception
Transcutaneous electrical nerve stimulation (TENS)
The delivery of electrical pulses through electrodes attached to the skin, which excite nerves that supply the region to which pain is referred. TENS can relieve the pain in some instances
Naloxone
A potent antagonist of opiates that is often administered to people who have taken drug overdoses. It binds to receptors for endogenous opioids
Placebo
A substance, given to a patient, that is known to be ineffective or inert but that sometimes brings relief
Acupuncture
The insertion of needles at designated points on the skin to alleviate pain or neurological malfunction
