Perception

PSY 511.003

Published

March 14, 2024

The big picture

Senses as (perception/action) systems

Gibson 1966

(Figure 10.2 from Swanson, 2012)

(Figure 1 from Swanson, 2005)

Smartphone as metaphor

  • Accelerometer
  • Gyroscope
  • Magnetometer
  • Proximity sensor
  • Ambient light sensor
  • Barometer
  • Thermometer
  • Mic
  • Camera
  • Radios (Bluetooth, wifi, cellular, GPS)

http://www.phonearena.com/news/Did-you-know-how-many-different-kinds-of-sensors-go-inside-a-smartphone_id57885

Perception/action system dimensions

  • Interoceptive
    • Body position, movement, posture
    • Internal status: hunger, thirst, arousal, discomfort/pain, etc.
  • Exteroceptive
    • Layout of environment, contents

Questions for interoception

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

Questions for exteroception

  • Who/What is out there?
  • Animate/inanimate?
    • Conspecific (same species)/non?
    • Threat/non?
    • Familiar/un?
    • Mate/non? or Friend/not?
    • Food source/non
  • Where is it?
    • Distance
      • Proximal
      • Distal
    • Elevation, azimuth
    • Coordinate frames
      • Self/ego (left of me)
      • Object (top of object)
      • Allo/world (North of College)
  • Where moving?

Questions for action

  • What kind of response?
    • External
      • Move body
        • Approach/avoid/freeze
        • Signal/remain silent
        • Manipulate
    • Internal
      • Change physiological state
  • Speed, quality, direction of response

Properties of the world

  • Behaviorally relevant conditions, events, and entities…
  • Generate patterns…
    • Chemical
    • Photic/electromagnetic
    • Mechanical/acoustic
  • That specialized sensors detect, and
  • Neural circuitry responds to
  • That yield internal states (short- and long-term)
  • That cause actions

Processing

Physics of sensation

Sorry, Mrs. Potraz, there are more than five senses!

Informal name Source
Vision Electromagnetic radiation
Audition Mechanical vibration in air/water
Touch Mechanical vibration of skin on surface
Vestibular Rotation & linear acceleration of head
Olfaction Chemical patterns in air/water
Gustation Chemical patterns in mouth
Electroception Electromagnetic radiation
Magnetoreception Electromagnetic radiation patterns
Kinesthesia Position, velocity, acceleration of limbs, body

Psychophysics (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?
  • Convey information at different rates, with varied precision
  • Information often signaled by multiple sources

Vision

  • Source: Electromagnetic radiation
    • Reflected from surfaces
  • 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
  • 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
  • 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
  • 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
  • Temperature
    • Receptors in skin, viscera
  • Mating interest
    • Receptors for hormones, NTs
    • ANS responses
  • Body position & movement (proprioception)
    • Receptors in muscles, joints, skin

(Figure 2 from Namkung, Kim, & Sawa, 2017). Figure 2. Interoceptive Information and Its Integration with Emotional, Cognitive, and Motivational Signals from an Array of Cortical and Subcortical Regions. Interoceptive information of constantly changing body states arrives in the posterior insula by ascending sensory inputs from dedicated spinal and brainstem pathways via specific thalamic relays. This information is projected rostrally onto the anterior insula, where it is integrated with emotional, cognitive, and motivational signals from an array of cortical and subcortical regions. As a result, the anterior insula supports unique subjective feeling states. The anterior insula regulates the introduction of subjective feelings into cognitive and motivational processes by virtue of its cortical location at the cross-roads of numerous pathways involved in higher cognition and motivation. Abbreviations: AI, anterior insula; AMG, amygdala; dACC, dorsal anterior cingulate cortex; DLPFC, dorsolateral prefrontal cortex; PI, posterior insula; THAL, thalamus; VMPFC, ventromedial prefrontal cortex; VS, ventral striatum.

Features of sensory signals

Change across time

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

https://www.researchgate.net/figure/Two-types-of-receptions-differing-by-the-rate-of-adaptation-to-the-dynamical-stimulus-A_fig1_51231510
  • Adaptation
    • Decline in sensitivity with sustained stimulation
    • Most sensory systems attuned 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

Consist of repeating signals (e.g. patterns)

  • In space (textures)
  • In time
Vision: Spatial frequency/contrast sensitivity

(Roark & Stringham, 2019)
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

“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://foundationsofvision.stanford.edu/chapter-6-the-cortical-representation/

Topographic maps

Auditory: Tonotopic maps

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830355/

Visual: Retinotopic maps

(Dougherty et al., 2003)

Somatosensory: Somatotopic maps in S1 & M1

Sensivity non-uniform

Two-point touch thresholds

Somatosensory homunculus

Visual acuity non-uniform

Wikipedia

Hearing thresholds non-uniform

http://auditoryneuroscience.com/

Hierarchical/sequential AND parallel

Feedforward and feedback

Case study: Vision

Animals respond to visual illusions, too

https://www.illusionsindex.org/i/rotating-snakes

A cat responds…

https://www.reddit.com/r/youseeingthisshit/comments/p9y7v1/the_reaction_of_the_cat_on_the_optical_illusion/?ref=share&ref_source=embed&utm_content=title&utm_medium=post_embed&utm_name=85f1a01593f447e092c5b300e5561d6e&utm_source=embedly&utm_term=p9y7v1

(Smith, Chouinard, & Byosiere, 2021)

(Smith et al., 2021)

Properties of Electromagnetic (EM) radiation

http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edit.svg
  • Wavelength/frequency
  • Intensity
  • Location/position of source
  • Reflects off some materials
  • Refracted (bent) moving through other materials
  • Information across space (and time)

http://apod.nasa.gov/apod/ap140605.html
  • Light provides fast (2.99 million m/s; 186 million mi/hr) information about surfaces at a distance
  • vs. sound (340 m/s; 767 mi/hr)
  • vs. chemical signals (min/mi)

Reflectance spectra differ by surface

Randeberg (2005)

http://http://www.vgt.vito.be/userguide/book_1/4/42/ie42bd.gif

Optic array specifies geometry of environment

Gibson

Categories of wavelength specify perception of color

  • Eyes categorize wavelength into relative intensities within wavelength bands
  • RGB ~ Red, Green, Blue
    • Long, medium, short wavelengths
  • Color is a neural/psychological construct

The biological camera

part of a self-stabilizing system…

https://www.youtube.com/embed/JGArTWOJtXs

Parts of the eye

  • Cornea - refraction (2/3 of total)
  • Pupil - light intensity; diameter regulated by Iris.
  • Lens - refraction (remaining 1/3; focus)
  • Retina - light detection
    • ~ skin or organ of Corti in inner ear
  • Pigment epithelium - regenerate photopigment
  • Muscles - move eye, reshape lens, change pupil diameter

Geometry of retinal image

  • Image inverted (up/down)
  • Image reversed (left/right)
  • Point-to-point map (retinotopic)
  • Binocular and monocular zones

The fovea

http://www.brainhq.com/sites/default/files/fovea.jpg
  • Central 1-2 deg of visual field
  • Aligned with visual axis
  • Retinal ganglion cells pushed aside
  • Highest acuity vision == best for details
  • Acuity varies from center to periphery

http://michaeldmann.net/pix_7/blndspot.gif
What part of the skin is like the fovea?

Photoreceptors in retina detect light

  • Rods
    • ~120 M/eye
    • Mostly in periphery
    • Active in low light conditions
    • One wavelength range
  • Cones
    • ~5 M/eye
    • Mostly in center
    • 3 wavelength ranges

https://foundationsofvision.stanford.edu/

http://cnx.org/content/col11496/1.6/

Photoreceptor physiology

  • Outer segment
    • Membrane disks
    • Photopigments
      • Sense light, trigger chemical cascade
  • Inner segment
    • Synaptic terminal
  • Light hyperpolarizes photoreceptor!
    • The dark current

Retina

  • Physiologically backwards
    • Dark current
  • Anatomically inside-out
    • Photoreceptors at back of eye

http://www.retinareference.com/anatomy/
  • Information flows…
    • From photoreceptors…
    • To Bipolar cells
      • <-> and Horizontal cells
    • To Retinal ganglion cells
      • <-> and Amacrine cells
    • To cerebral cortex

Center-surround receptive fields

  • Center region
    • Excites (or inhibits)
  • Surround region
    • Does the opposite
  • Bipolar cells & Retinal Ganglion cells ->
  • Most activated by “donuts” of light/dark
    • Local contrast (light/dark differences)

Opponent processing

http://www.visualexpert.com/sbfaqimages/RGBOpponent.gif
  • Black (darker) vs. white (lighter) (achromatic)
  • Long (red) vs. Medium (green) wavelength cones
  • (Long + Medium) vs. Short cones
  • Can’t really see reddish-green or bluish-yellow
    • “Oppose” one another at cellular/circuit level
    • DEMO

From eye to brain

  • Retinal ganglion cells
  • 2nd/II cranial (optic) nerve
    • Optic chiasm (\(\chi\) - asm): Partial crossing of fibers
    • Nasal hemiretina (lateral/peripheral visual field) cross
    • Left visual field (from L & R retinae) -> right hemisphere & vice versa
  • Lateral Geniculate Nucleus (LGN) of thalamus (receives 90% of retinal projections)
  • Hypothalamus
    • Suprachiasmatic nucleus (superior to the optic chiasm): Synchronizes day/night cycle with circadian rhythms
  • Superior colliculus & brainstem

LGN

  • 6 layers + intralaminar zone
    • Parvocellular (small cells): chromatic
    • Magnocellular (big cells): achromatic
    • Koniocellular (chromatic - short wavelength?)
  • Retinotopic map of opposite visual field

From LGN to V1

  • Via optic radiations
  • Primary visual cortex (V1) in occipital lobe
  • Create “stria of Gennari” (visible stripe in layer 4)
  • Calcarine fissure (medial occiptal lobe) divides lower/upper visual field

Human V1

http://www.scholarpedia.org/w/images/3/3a/03-Human-V1.png

(Dougherty et al., 2003)
  • Fovea overrepresented
    • Analogous to somatosensation
    • High acuity in fovea vs. lower outside it
  • Upper visual field/lower (ventral) V1 and vice versa

Laminar, columnar organization

  • 6 laminae (layers)
    • Input: Layer 4 (remember stria of Gennari?)
    • Output: Layers 2-3 (to cortex), 5 (to brainstem), 6 (to LGN)
  • Columns
    • Orientation/angle
    • Spatial frequency
    • Color/wavelength
    • Eye of origin, ocular dominance

https://foundationsofvision.stanford.edu/wp-content/uploads/2012/02/dir.selective.png

From center-surround receptive fields to line detection

(Panichello, Cheung, & Bar, 2013)

Ocular dominance columns

Beyond V1

  • Larger, more complex receptive fields
  • Dorsal stream (where/how)
    • Toward parietal lobe
  • Ventral stream (what)

What is vision for?

  • What is it? (form perception)
  • Where is it? (space perception)
  • How do I get from here to there (action control)
  • What time (or time of year) is it?

References

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
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
Panichello, M. F., Cheung, O. S., & Bar, M. (2013). Predictive feedback and conscious visual experience. Perception Science, 3, 620. https://doi.org/10.3389/fpsyg.2012.00620
Randeberg, L. (2005). Diagnostic applications of diffuse reflectance spectroscopy. Retrieved from https://www.semanticscholar.org/paper/ec9450b79923e2e2152b54ab9241b60bc5374944
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
Smith, G. E., Chouinard, P. A., & Byosiere, S.-E. (2021). If I fits I sits: A citizen science investigation into illusory contour susceptibility in domestic cats (felis silvestris catus). Applied Animal Behaviour Science, 240, 105338. https://doi.org/10.1016/j.applanim.2021.105338
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.