Chapter 5: Sensation and Perception

a neuron’s most preferred area(s) on a body surface, or in space, as indicated by the neuron’s most increased responsiveness, when compared with this neuron’s less responsiveness to activation(s) of other area(s)

a neuron’s less preferred area(s) on a body surface, or in space, as indicated by the neuron’s decreased responsiveness when compared with the neuron’s principal receptive field

that one neuron can have many principal, and many surround, receptive fields

proper ability to filter out “irrelevant” incoming sensory stimuli for our perceptions because of the balance of excitatory inputs and inhibitory inputs that neurons receive

• -provide excitatory inputs to neurons in the thalamus (subcortical) – these neurons in the thalamus then provide both excitatory inputs, and inhibitory inputs, to neurons in cortical layer IV for the particular sense -Sensory transduction, for all our senses, begins with the activation(s) of first order neurons (sensory cranial nerves and sensory spinal nerves); these first order neurons reach their thresholds of activations only when “specific intensities of environmental stimuli” are emitted

a class of neurons that activate in response to actions and emotions we observe in others hypothesized to understand the actions of others

Sensation – cognitive ability to detect environmental “non-biological” stimuli, so that this detection activates our sensory system(s) Perception – cognitions during which we integrate, organize and interpret incoming sensory information that is useful and meaningful for us

Vision Auditory or audition (hearing) Cutaneous (pressure, vibration, pain, temperature) Olfactory or olfaction (smell) Gustatory or gustation (taste)

Conversion of environmental stimuli, into “biological, neural” signals for the successful detection of these environmental stimuli essenatially encoding sensory stimuli into neural patterns to be interpretted

cutaneous (touch) stimuli below the head

procedures that measure the intensity of an environmental stimulus, and a person’s ability to detect this intensity to activate our senses One of the goals of psychophysics is to determine the intensity of the environmental stimulus required to evoke (or bring forth) activation of our sensory system(s) Examples of outcomes due to implementing psychophysics 1) Just Noticeable Difference (JND) 2) Absolute Threshold

when comparing different intensities of an environmental stimulus, the JND is the minimal change in intensity of this environmental stimulus that is needed for us to detect this change in intensity formula: where k = ((triangle)*i )/ i i - intensity of og stimulus (triangle i) - the difference in intensity between the comparison environmental stimulus, and the original environmental stimulus ( Note: if triangle i in intensity is the minimum intensity by which the comparison environmental stimulus differs from the original environmental stimulus that allows detection by humans, then this is the difference threshold, or the JND, for this particular environmental stimulus)

“minimum” intensity of the environmental stimulus needed for sensory transduction to occur Form a classical point of view, experimenters have derived the absolute threshold from participants’ reporting of their ability to correctly detect the presence of an environmental stimulus 50% of the time this environmental stimulus was presented

(From surface most to surface least) Cone and Rod cells (the first to be activated)

rod cell, when activated by light, releases glutamate–thus its most sensitive tio shades of black and white/ light and dark cone cell, is more colour sensitive than it is simply light sensitive

S cones (receptive to 437 nm wavelengths and tranduces the colour yellow) M cones (Receptive to 533 nm wavelengths to transduce the colour red L cones (receptive to 564 nm wavelengths to transduce indigo)

Clusters of cell body areas of all cranial nerves, and of all spinal nerves, for the relaying of sensory information

First order neurons

in the front layer of the retina – they are the last layer of cells in the retina to be activated and the first order neurons in visual stimuli bc the axons of the retinal ganglion are the first to go directly into the brain

The fovea

Compression: surrounding air particles, of the ear, are pushed together to cause an increase in the density of the particles Rarefaction: surrounding air particles, of the ear, spread to “fill in” space to cause a decrease in density of air particles

Sound waves from air particles»_space;> ear canal»_space;» vibration of tympanic membrane »_space;» malleus transmits vibrations to incus and stapes»_space;> which then transmits vibrations to spiral ganglion in cochlea»_space; spiral ganglion in the cochlea

Spiral ganglion

To the left side, as the spiral ganglion are not firing action potentials