Pupillary response
{{Short description|Physiological response that varies the size of the pupil}}
Pupillary response is a physiological response that varies the size of the pupil between 1.5 mm and 8 mm,{{Cite journal |last=McDougal |first=David H. |last2=Gamlin |first2=Paul D. |year=2015 |title=Autonomic Control of the Eye |journal=Comprehensive Physiology |volume=5 |pages=439-473 |doi=10.1002/cphy.c140014|pmc=4919817 }} via the optic and oculomotor cranial nerve.
A constriction response (miosis),{{cite journal | vauthors = Ellis CJ | title = The pupillary light reflex in normal subjects | journal = The British Journal of Ophthalmology | volume = 65 | issue = 11 | pages = 754–9 | date = November 1981 | pmid = 7326222 | pmc = 1039657 | doi = 10.1136/bjo.65.11.754 | url = }} is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications. Constriction of the pupil occurs when the circular muscle, controlled by the parasympathetic nervous system (PSNS), contracts, and also to an extent when the radial muscle relaxes.
File:Voluntary pupil dilation.gif
A dilation response (mydriasis), is the widening of the pupil and may be caused by adrenaline; anticholinergic agents; stimulant drugs such as MDMA, cocaine, and amphetamines; and some hallucinogenics (e.g. LSD).{{Citation |author=Jaanus SD |title=Ocular side effects of selected systemic drugs |journal=Optom Clin |volume=2 |issue=4 |pages=73–96 |year=1992 |pmid=1363080 }} Dilation of the pupil occurs when the smooth cells of the radial muscle, controlled by the sympathetic nervous system (SNS), contract, and also when the cells of the iris sphincter muscle relax.
File:Pupillary light reflex.jpg
The responses can have a variety of causes, from an involuntary reflex reaction to exposure or inexposure to light—in low light conditions a dilated pupil lets more light into the eye—or it may indicate interest in the subject of attention or arousal, sexual stimulation,{{cite journal | vauthors = Hess EH, Polt JM | title = Pupil size as related to interest value of visual stimuli | journal = Science | volume = 132 | issue = 3423 | pages = 349–50 | date = August 1960 | pmid = 14401489 | doi = 10.1126/science.132.3423.349 | bibcode = 1960Sci...132..349H | s2cid = 12857616 | author1-link = Eckhard Hess }} uncertainty,{{cite journal | vauthors = Nassar MR, Rumsey KM, Wilson RC, Parikh K, Heasly B, Gold JI | title = Rational regulation of learning dynamics by pupil-linked arousal systems | journal = Nature Neuroscience | volume = 15 | issue = 7 | pages = 1040–6 | date = June 2012 | pmid = 22660479 | doi = 10.1038/nn.3130 | pmc = 3386464 }} decision conflict,{{cite journal | vauthors = Lin H, Saunders B, Hutcherson CA, Inzlicht M | title = Midfrontal theta and pupil dilation parametrically track subjective conflict (but also surprise) during intertemporal choice | journal = NeuroImage | volume = 172 | pages = 838–852 | date = May 2018 | pmid = 29107773 | doi = 10.1016/j.neuroimage.2017.10.055 | s2cid = 4960140 | url = https://discovery.dundee.ac.uk/en/publications/c404d52a-4ed8-48db-8f95-6bfc464581b4 }} errors,{{Cite journal|last1=Decker|first1=Alexandra|last2=Finn|first2=Amy|last3=Duncan|first3=Katherine|date=2020-11-01|title=Errors lead to transient impairments in memory formation|url=http://www.sciencedirect.com/science/article/pii/S0010027720301578|journal=Cognition|language=en|volume=204|pages=104338|doi=10.1016/j.cognition.2020.104338|pmid=32593745|s2cid=220044505|issn=0010-0277|url-access=subscription}} physical activity{{Cite journal |last1=Kuwamizu |first1=Ryuta |last2=Yamazaki |first2=Yudai |last3=Aoike |first3=Naoki |last4=Ochi |first4=Genta |last5=Suwabe |first5=Kazuya |last6=Soya |first6=Hideaki |date=2022-09-24 |title=Pupil-linked arousal with very light exercise: pattern of pupil dilation during graded exercise |journal=The Journal of Physiological Sciences |volume=72 |issue=1 |pages=23 |doi=10.1186/s12576-022-00849-x |pmid=36153491 |issn=1880-6562|doi-access=free |pmc=10717467 }} or increasing cognitive load{{cite journal | vauthors = Kahneman D, Beatty J | title = Pupil diameter and load on memory | journal = Science | volume = 154 | issue = 3756 | pages = 1583–5 | date = December 1966 | pmid = 5924930 | doi = 10.1126/science.154.3756.1583 | bibcode = 1966Sci...154.1583K | s2cid = 22762466 }} or demand. The responses correlate strongly with activity in the locus coeruleus neurotransmitter system.{{cite journal | vauthors = Aston-Jones G, Cohen JD | title = An integrative theory of locus coeruleus-norepinephrine function: adaptive gain and optimal performance | journal = Annual Review of Neuroscience | volume = 28 | issue = 1 | pages = 403–50 | date = 2005-07-21 | pmid = 16022602 | doi = 10.1146/annurev.neuro.28.061604.135709 | s2cid = 535645 }}{{cite journal | vauthors = Joshi S, Li Y, Kalwani RM, Gold JI | title = Relationships between Pupil Diameter and Neuronal Activity in the Locus Coeruleus, Colliculi, and Cingulate Cortex | journal = Neuron | volume = 89 | issue = 1 | pages = 221–34 | date = January 2016 | pmid = 26711118 | pmc = 4707070 | doi = 10.1016/j.neuron.2015.11.028 }}{{cite journal | vauthors = Murphy PR, O'Connell RG, O'Sullivan M, Robertson IH, Balsters JH | title = Pupil diameter covaries with BOLD activity in human locus coeruleus | journal = Human Brain Mapping | volume = 35 | issue = 8 | pages = 4140–54 | date = August 2014 | pmid = 24510607 | pmc = 6869043 | doi = 10.1002/hbm.22466 }} The pupils contract immediately before REM sleep begins.{{cite journal | vauthors = Lowenstein O, Feinberg R, Loewenfeld IE
|author1-link = Otto Lowenstein
|title = Pupillary Movements During Acute and Chronic Fatigue: A New Test for the Objective Evaluation of Tiredness
|journal = Investigative Ophthalmology
|publisher = C.V. Mosby Company
|place = St. Louis
|volume = 2
|issue = 2
|pages = 138–157
|date = April 1963
|url = http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-09.pdf
|url-status = dead
|archive-url = https://web.archive.org/web/20120319233224/http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-09.pdf
|archive-date = 2012-03-19
}}
A pupillary response can be intentionally conditioned as a Pavlovian response to some stimuli.{{cite journal | last = Baker | first = Lynn Erland | name-list-style = vanc | author-link = Lynn Baker | title = The Pupillary Response Conditioned to Subliminal Auditory Stimuli | publisher = Ohio State University | date = 1938 | oclc = 6894644 }}
Some humans have the ability to exert direct and voluntary control over their iris sphincter muscles and dilator muscles, granting them the ability to dilate and constrict their pupils on command, regardless of lighting condition and/or eye accommodation state.{{Cite journal |last=Eberhardt |first=Lisa V. |last2=Grön |first2=Georg |last3=Ulrich |first3=Martin |last4=Huckauf |first4=Anke |last5=Strauch |first5=Christoph |date=2021-10-01 |title=Direct voluntary control of pupil constriction and dilation: Exploratory evidence from pupillometry, optometry, skin conductance, perception, and functional MRI |url=https://www.sciencedirect.com/science/article/pii/S0167876021008448 |journal=International Journal of Psychophysiology |volume=168 |pages=33–42 |doi=10.1016/j.ijpsycho.2021.08.001 |issn=0167-8760|doi-access=free }} However, this ability is very rare, and its potential use or advantages are unclear.
The latency of pupillary response (the time in which it takes to occur) increases with age.{{cite book | vauthors = Feinberg R, Podolak E
|title = Latency of pupillary reflex to light stimulation and its relationship to aging
|url = http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-25.pdf
|publisher = Federal Aviation Agency, Office of Aviation Medicine, Georgetown Clinical Research Institute
|page = 12
|date = September 1965
|oclc = 84657376
|url-status = dead
|archive-url = https://web.archive.org/web/20120320010318/http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-25.pdf
|archive-date = 2012-03-20
}}
In ophthalmology, intensive studies of pupillary response are conducted via videopupillometry.{{cite journal | vauthors = Ishikawa S, Naito M, Inaba K | title = A new videopupillography | journal = Ophthalmologica | volume = 160 | issue = 4 | pages = 248–59 | date = 1970 | pmid = 5439164 | doi = 10.1159/000305996 }}
Anisocoria is the condition of one pupil being more dilated than the other.
File:Horner's Syndrome and Autonomic innervation of the eye.svg
| class="wikitable"
|+ Pupillary responses | ! Constriction (Parasympathetic) !! Dilation (Sympathetic) |
| Muscular mechanism
| Relaxation of iris dilator muscle, activation of iris sphincter muscle || Activation of iris dilator muscle, relaxation of iris sphincter muscle |
|---|
| Cause in pupillary light reflex
| Increased light || Decreased light |
| Other physiological causes
| Accommodation reflex || Fight-or-flight response, sexual arousal |
| Corresponding non-physiological state |