Ch8-General Principles of Sensation

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Questions and Answers

How is intensity encoded in sensory processing?

Exclusively by the frequency of action potentials

Only by the density of receptors in the area

By which neurons are active and the number of action potentials (correct)

Only by the type of neurons active

What characteristic differentiates tonic and phasic receptors?

Phasic receptors have a higher density than tonic receptors in sensory organs.

Tonic receptors adapt quickly, while phasic receptors show slow adaptation.

Phasic receptors represent different stimulus intensities, while tonic receptors remain constant.

Tonic receptors show slow or no adaptation, while phasic receptors undergo rapid adaptation. (correct)

What role does neural assembly play in encoding intensity?

They solely represent the total number of action potentials in a single neuron.

Neural assemblies only encode tone frequency.

Neural assemblies do not affect intensity encoding.

Assemblies can recruit different neurons for higher intensities. (correct)

Which statement about the processing of stimulus frequency is correct?

Both which neurons are active and the number of action potentials indicate frequency. Signup and view all the answers

How do sensory systems adapt to maintain accurate representation of stimuli?

By adjusting the incoming sensory information at the receptor level. Signup and view all the answers

What is the correct sequence of the stages of sensation?

Reception, Transduction, Coding Signup and view all the answers

Which of the following best describes the function of sensory receptors?

They detect specific physical stimuli and convert them to electrochemical signals. Signup and view all the answers

What is meant by the term 'receptive fields' in sensory processing?

Distinct regions that activate certain neurons in response to stimuli. Signup and view all the answers

How does lateral inhibition enhance sensory processing?

By suppressing the activity of adjacent neurons, enhancing contrast. Signup and view all the answers

What does hierarchical processing in sensory systems imply?

Lower levels of sensory processing are responsible for basic features, which are integrated at higher levels. Signup and view all the answers

What type of information do nociceptors primarily convey?

Pain and heat sensations Signup and view all the answers

Which statement about sensory receptors is false?

Sensory receptors are responsible for processing all forms of incoming information. Signup and view all the answers

What role does coding play in sensation?

Corresponds specific aspects of stimuli to patterns of action potentials. Signup and view all the answers

What is the function of receptive fields in sensory processing?

To sharpen and define sensory inputs Signup and view all the answers

How do receptive fields generally differ between sensitive and less sensitive systems?

Sensitive systems have smaller receptive fields Signup and view all the answers

What is the role of lateral inhibition in sensory recognition?

It sharpens the acuity of sensory recognition Signup and view all the answers

In hierarchical processing, what occurs at successive levels of stimulus processing?

Extraction of more complex attributes Signup and view all the answers

Where is most sensory information relayed before reaching appropriate cortical circuits?

Thalamus Signup and view all the answers

Which statement correctly describes the relationship between receptive fields and stimulus localization?

Smaller receptive fields are crucial for detecting movement Signup and view all the answers

What limits the processing of stimulus localization and movement direction?

The spatial organization of receptive field inputs Signup and view all the answers

During the sensory processing stages, what is primarily enhanced through lateral inhibition?

Contrast and clarity of specific stimuli Signup and view all the answers

What best describes the function of successive levels of processing in sensory systems?

To refine and analyze complex properties of stimuli Signup and view all the answers

What can be inferred about larger receptive fields in less sensitive systems?

They provide less acuity in sensory recognition Signup and view all the answers

Study Notes

General Principles of Sensory Processing

Five senses: vision, audition, somatosensation, gustation, olfaction
Each sensory system processes various stimulus attributes
Each sensory system has multiple receptors and neural pathways to integrate features of stimuli. Additional senses include vestibular for balance, temperature, pain, and proprioception.
There are distinct hierarchical neural pathways for various sensory systems.

Stimulus Salience

Umwelt is a species-specific perceptual world, differing between species
Salience is a consequence of brain processing. Important modalities occupy larger brain regions
Different animal species have varying hearing ranges which influence stimuli salience for social interactions

Sensation and Perception

Sensation: detection and recognition of a stimulus
Perception: interpretation and appreciating the stimulus
Different species construct different sensations and perceptions.

The Doctrine of Specific Nerve Energies (Johannes Müller)

Sensory inputs use different nerve "energies" interpreted by the brain to create specific perceptions.
The brain is functionally divided with specific nerves conveying specific types of information
Sensations depend on which neurons are active and to what degree.

Sensory Receptors

Specialized neurons detecting specific physical stimuli
Key distinction: these are not neurotransmitter/hormone receptors
Most sensory receptors do not have axons; they synapse with other neurons

Three Stages of Sensation

Reception: absorption of physical energy by sensory receptors
Transduction: conversion of physical energy to electrochemical patterns in neurons
Coding: correspondence between aspects of the physical stimulus and action potentials in the brain.

Organization of Sensory Inputs

Sensory systems are topographically organized
Sensory information is relayed through the thalamus to cortical circuits, with varying degrees of processing.

Processing of Stimulus Intensity

Intensity can be encoded by active neurons or firing frequency.
Intensity range is processed beyond individual neuron firing, with assemblies of neurons encoding diverse intensities.

Processing of Stimulus Frequency

Frequency can be encoded by active neurons or number of action potentials.
Frequency is encoded differently compared to intensity encoding, and firing rates are limited. Cochlear hair cells encode different sound frequencies along the basilar membrane; different frequencies are processed at different locations.

Adaptation to a Stimulus

Tonic receptors: slow or no adaptation
Phasic receptors: rapid adaptation
Neural activity and perception may change as a consequence of adaptation.

Plasticity in Sensory Processing

Experience-dependent plasticity in topographical organization of somatosensory maps.
Sensory input can reorganize based on peripheral lesions or environmental stimulation.

Somatosensation - Epicritic and Protopathic Touch

Epicritic touch: fine, discriminative touch (mechanoreceptors)
Protopathic touch: nondiscriminating, pain, and temperature (free nerve endings)

Somatosensation - Pathway Components

Sensory neurons (afferent) that carry information from the skin and other body parts are the first-order neurons. These neurons synapse with second-order neurons in the spinal cord or brainstem.
Second-order neurons decussate, which means they cross over to the opposite side of the body before traveling to the thalamus
Third-order neurons synapse in the thalamus and carry information to the primary sensory cortex.
There are both dorsal column medial lemniscal pathways and spinothalamic pathways for somatosensation. The dorsal column-medial lemniscus pathway is for fine touch, pressure, and proprioception, whereas the spinothalamic pathway is for pain, temperature, and crude touch.

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Description

This quiz explores the complexities of sensory processing, focusing on the five primary senses and additional sensory modalities. It delves into how different animals perceive their environment and the distinction between sensation and perception. Learn about the neural pathways that facilitate these critical functions.