Sensory Systems

2025-11-13

Rick Gilmore

Department of Psychology

Prelude

– TheWhoVEVO (2016)

Today’s topics

• Warm up
• Sensory systems

Warm up

Which of the following brain areas are not implicated in the threat conditioning paradigm?

• A. amygdala
• B. auditory thalamus
• C. somatosensory thalamus
• D. visual cortex (V1)

Which of the following brain areas are not implicated in the threat conditioning paradigm?

• A. amygdala
• B. auditory thalamus
• C. somatosensory thalamus
• D. visual cortex (V1)

Medina, Repa, Mauk, & LeDoux (2002) Figure 2

The hypothalamus gets input from this structure as part of the system regulating hormonal and ANS responses to threat.

• A. ventral tegmental area (VTA)
• B. amygdala
• C. cerebellum
• D. olfactory bulb

The hypothalamus gets input from this structure as part of the system regulating hormonal and ANS responses to threat.

• A. ventral tegmental area (VTA)
• B. amygdala
• C. cerebellum
• D. olfactory bulb

Whether stressors are ______ or _______ influences whether they cause long-term health problems.

• A. loud; quiet
• B. bright; dim
• C. social; chemical
• D. acute; chronic

Whether stressors are ______ or _______ influences whether they cause long-term health problems.

• A. loud; quiet
• B. bright; dim
• C. social; chemical
• D. acute; chronic

Sensory Systems

Minds in the world

Perception/action systems

Gibson 1966

Perception/action systems

Figure 10.2 from Swanson (2012)

Figure 1 from Swanson (2005)

My smartphone and me…

Smartphone design goals

• What information do your users need to acquire?
• Why do they need to know it? In what context, for what purpose?
• What types of information does your device need to gather, through which channels?

Important

• Animal sensory systems not designed per se
• Evolution via natural selection can look like design

Smartphone sensors

• Accelerometer
• Gyroscope
• Magnetometer
• Proximity sensor
• Ambient light sensor

• Barometer
• Thermometer
• Mic
• Camera
• Radios (Bluetooth, wifi, cellular, GPS)

– Todorov (2014)

My turn…

• What information do I need to acquire?
• Why do I need to know it? In what context & for what purpose?
• What types of information do I need to gather, through which channels?

Types of sensory processing

• Interoceptive
  • How am I?
• Exteroceptive
  • What’s in the world, where is it?

Questions for interoception

• Tired or rested?
• Well or ill?
• Hungry or thirsty or sated?
• Stressed vs. coping?
• Emotional state?
• Where am I?

Barker, Brewer, & Murphy (2021)

“Scripps research-led team receives $14.2M NIH award to map the body’s ‘hidden sixth sense’” (2025)

Questions for exteroception

• Who/What is out there?
• Where is it?

Mrs. Potraz was wrong…

• More than 5 senses!

From physics to psychology

• What is the energy/chemical channel?
• Channels carry different types of information about
  • What is out there?
  • Where is it located or moving?
• Channels convey information
  • at different rates
  • with varied precision
• Similar information often signaled by multiple sources

Psychophysics

• Earliest field of scientific psychology, origins in mid-1800s
• How precisely do human observers detect physical properties?
• Emphasizes quantitative relationships, precise measurement
• More: Wikipedia contributors (2025)

Case studies in sensory systems

• Vision
• Audition
• Chemosensation
• Somatosensation

Vision

• Source: Electromagnetic radiation
• Reflected from surfaces
• Emitted by sources (e.g., sun, screens)

Wikipedia

Vision

• What is it?
  • Shape, size, surface properties (color, texture, reflectance, etc.)
  • Wavelength/frequency, intensity
• Where is it?
  • Position: Left/right; up/down on retina
  • Near/far: retinal disparity, interposition, height above horizon…
  • Orientation, motion

Audition

• Source: Mechanical vibrations in air or water

Audition

• What is it?
  • Pattern of frequencies, amplitudes, durations
• Where is it?
  • Left/right or up/down: Interaural time/phase, intensity differences, pinnae filtering
  • Motion: Frequency shifts via Doppler effect

Chemosensation

• Source: Chemicals in mouth, nasal cavity, elsewhere

Bargmann (2006)

Chemosensation

• What is it?
  • Mixtures of chemicals
• Where is it?
  • Left/right; up/down; near/far via intensity gradients

Somatosensation

• Source: Thermal or mechanical stimulation (vibration/pressure) of skin

https://basicmedicalkey.com/the-somatosensory-system/

Somatosensation

• What is it?
  • Shape, size, smoothness, mass, temperature, deformability: Pattern of stimulation
• Where it it?
  • Pattern of cutaneous receptors on skin

Interoception

• Hunger/thirst
  • Receptors for nutrient, fluid levels
• Energy levels
  • Receptors for hormones, NTs
  • ANS responses

Figure 2 from Namkung, Kim, & Sawa (2017)

Interoception

• Temperature
  • Receptors in skin, viscera
• Body position & movement (proprioception)
  • Receptors in muscles, joints, skin

Figure 2 from Namkung et al. (2017)

Common features

• Signals change across time and space
  • Consist of repeating patterns
• Involve comparisons across multiple sensors
• Specialized neurons
• Receptive fields
• Brain regions contain topographic maps
• Sensitivity is non-uniform

Change across time

• Tonic (sustained) vs. phasic (transient) responses

https://humanphysiology.academy/Neurosciences%202015/Chapter%202/P.2.1%20Afferents.html

Change across time

• Adaptation
  • Decline in sensitivity with sustained stimulation
  • Most sensory systems attuned to change

https://hoeftvision.weebly.com/adaptation.html

Measuring sensitivity to change

• Just noticeable difference (JND): How much of a change is noticeable?
  • Most psychophysical functions are non-linear
  • JND a function of absolute intensity!

Psychophysical functions

Information propagates in CNS at different speeds

• Bigger diameter: Faster
• Denser myelin: Faster

Information consists of repeating signals

• e.g., patterns
• In space (textures)
• In time

Vision

• Spatial frequency/contrast sensitivity

Roark & Stringham (2019) Figure 1

Audition

• Frequencies in sound

https://www.mwmresearchgroup.org/blog/key-concepts-fourier-transforms-and-signal-processing

Somatosensation:

• Textures

Figure 1 from https://www.frontiersin.org/articles/10.3389/fnhum.2022.862344/full

Compare (>1) sensors located in different parts of the body

• Eyes
• Ears
• Skin surface
• Nostrils
• Tongue

Specialized neurons

• Photoreceptors

Wikipedia

Specialized neurons

• Cochlear hair cells

Specialized neurons

• taste receptor cells

Chandrashekar, Hoon, Ryba, & Zuker (2006)

“Receptive fields”

• Area on sensory surface (e.g., retina, skin) that when stimulated changes neuron’s firing

Tactile

https://www.nursinghero.com/study-guides/austincc-ap1/pain

Visual

https://openbooks.lib.msu.edu/neuroscience/chapter/vision-the-retina/

https://wandell.github.io/FOV-1995/

Topographic maps

Auditory: Tonotopic maps

Humphries, Liebenthal, & Binder (2010) Figure 3

Visual: Retinotopic maps

Visual: Retinotopic maps

Dougherty et al. (2003) Figure 1

Somatotopic maps

http://bio1152.nicerweb.com/Locked/media/ch49/49_16-MotorSensoryCorts-L.jpg

Sensivity non-uniform

Visual acuity non-uniform

Wikipedia

Hearing thresholds non-uniform

http://auditoryneuroscience.com/

Two-point touch thresholds

– OTGeddie (2017)

Somatosensory homunculus

Sequential & parallel processing

Wrap up

Main points

• Psychology originated with the study of perception
• Closing the behavioral loop
  • from sensation to action
  • important scientific goal

Main points

• Interoception vs. exteroception
• Key questions for exteroception
  • What’s out there (or who)?
  • Where is it?

Main points

• Sensory systems specialized (e.g., detect light, sound, chemicals)
• But have similarities
• Know more about (except interoception)
  • Easier to measure
  • Easier to access

Next time

• Somatosensation

Resources

About

This talk was produced using Quarto, using the RStudio Integrated Development Environment (IDE), version 2025.9.2.418.

The source files are in R and R Markdown, then rendered to HTML using the revealJS framework. The HTML slides are hosted in a GitHub repo and served by GitHub pages: https://psu-psychology.github.io/psych-260-2025-fall/

References

Bargmann, C. I. (2006). Comparative chemosensation from receptors to ecology. Nature, 444, 295–301. https://doi.org/10.1038/nature05402

Barker, M., Brewer, R., & Murphy, J. (2021). What is interoception and why is it important? Frontiers for Young Minds, 9. https://doi.org/10.3389/frym.2021.558246

Chandrashekar, J., Hoon, M. A., Ryba, N. J. P., & Zuker, C. S. (2006). The receptors and cells for mammalian taste. Nature, 444, 288–294. https://doi.org/10.1038/nature05401

Dougherty, R. F., Koch, V. M., Brewer, A. A., Fischer, B., Modersitzki, J., & Wandell, B. A. (2003). Visual field representations and locations of visual areas V1/2/3 in human visual cortex. Journal of Vision, 3(10), 1–1. https://doi.org/10.1167/3.10.1

Humphries, C., Liebenthal, E., & Binder, J. R. (2010). Tonotopic organization of human auditory cortex. NeuroImage, 50, 1202–1211. https://doi.org/10.1016/j.neuroimage.2010.01.046

Medina, J. F., Repa, J. C., Mauk, M. D., & LeDoux, J. E. (2002). Parallels between cerebellum-and amygdala-dependent conditioning. Nature Reviews Neuroscience, 3(2), 122–131. https://doi.org/10.1038/nrn728

Namkung, H., Kim, S.-H., & Sawa, A. (2017). The insula: An underestimated brain area in clinical neuroscience, psychiatry, and neurology. Trends in Neurosciences, 40(4), 200–207. https://doi.org/10.1016/j.tins.2017.02.002

OTGeddie. (2017). Tactile localization. YouTube. Retrieved from https://www.youtube.com/watch?v=t97QiEiKjD8

Roark, M. W., & Stringham, J. M. (2019). Visual performance in the “real world”: Contrast sensitivity, visual acuity, and effects of macular carotenoids. Molecular Nutrition & Food Research, 63(15), e1801053. https://doi.org/10.1002/mnfr.201801053

Scripps research-led team receives $14.2M NIH award to map the body’s “hidden sixth sense.” (2025, October 8). Retrieved November 13, 2025, from https://www.scripps.edu/news-and-events/press-room/2025/20251008-nih-award.html

Swanson, L. W. (2005). Anatomy of the soul as reflected in the cerebral hemispheres: Neural circuits underlying voluntary control of basic motivated behaviors. Journal of Comparative Neurology, 493(1), 122–131. https://doi.org/10.1002/cne.20733

Swanson, L. W. (2012). Brain architecture: Understanding the basic plan. Oxford University Press.

TheWhoVEVO. (2016). The who - pinball wizard (live at the isle of wight, 1970). YouTube. Retrieved from https://www.youtube.com/watch?v=-J03yCE15rg&list=RD-J03yCE15rg&start_radio=1

Todorov, N. (2014, July 6). Did you know how many different kinds of sensors go inside a smartphone? Retrieved March 27, 2023, from https://www.phonearena.com/news/Did-you-know-how-many-different-kinds-of-sensors-go-inside-a-smartphone_id57885

Wikipedia contributors. (2025, August 17). Psychophysics. Retrieved from https://en.wikipedia.org/wiki/Psychophysics