06. Important information Flashcards
Why have sensory systems evolved in animals?
In order to guide their behaviour and provide specific kind of information the animal needs to survive and reproduce
Define sensation
The psychological experience associated with sound, light, or other simple stimuli and the initial information-processing steps by which sense organs and neural pathways take in stimulus information from the environment.
Define perception
The recognition, organisation, and meaningful interpretation of sensory stimuli.
What are the steps in the process of sensation
physical stimulus- physiological response- sensory experience
True or false: each sense has distinct sensory receptors and neural pathways to and within the brain?
true
What are sensory receptors?
Specialised biological structures—which in some cases are separate cells and in other cases are the sensitive tips of sensory neurons—that respond to physical stimuli by producing electrical changes that can initiate neural impulses (action potentials) in sensory neurons.
What are sensory areas?
Areas of the brain’s cerebral cortex that receive and analyse input from the body’s senses. Separate sensory areas exist for each distinct sense.
What is sensory coding?
The process by which information about the quality and quantity of a stimulus is preserved in the pattern of action potentials sent through sensory neurons to the central nervous system
What is transduction?
The process by which a receptor cell produces an electrical change in response to physical stimulation.
What are receptor potentials?
Electrical changes in neurons that can trigger action potentials in sensory neurons
How does the coding of stimulus quality occur?
Qualitatively different stimuli optimally activate different sets of neurons
What is sensory adaptation?
The temporary decrease in sensitivity to sensory stimulation that occurs when a sensory system is stimulated for a period of time, and the temporary increase in sensitivity that occurs when a sensory system is not stimulated for a period of time.
What is pyschophysics?
The scientific study of the relationship between physical characteristics of stimuli and the psychological (sensory) experiences that the stimuli produce.
What is the absolute threshold?
In psychophysics, the faintest (lowest-intensity) stimulus of a given sensation (such as sound or light) that an individual can detect.
What is the difference threshold?
In psychophysics, the minimal difference that must exist between two otherwise similar stimuli for an individual to detect them as different; also called the just-noticeable difference (jnd).
What is Weber’s law?
The idea that, within a given sensory modality (such as vision), the difference threshold (amount that the stimulus must be changed in magnitude to be perceived as different) is a constant proportion of the magnitude of the original stimulus.
What is signal detection theory?
Proposes that the detection of a sensory stimulus is dependent upon both the physical intensity of the stimulus and the psychological state (including expectations, motivation, and alertness) of the perceiver.
Why are smell and tase called chemical senses?
Because the stimuli for them are chemical molecules
Define olfaction
Sense of smell
How many different types of sensory neurons are contained in the olfactory nerve and where are their terminals located?
roughly 400 different types, the olfactory epithelium
Where do the glomeruli in the olfactory bulb send most of their output and what effect might this account for
Most output goes to structures in the limbic system and the hypothalamus which are involved in basic drives and emotions. These connections account for the strong and often unconscious effects that smell can have on our motivational and emotional states
Where are the primary and secondary olfactory areas located?
Primary- underside of the temporal lobe
Secondary- orbitofrontal cortex located at the underside of the frontal lobe
Areas are crucial for the conscious understanding of and identifying of odors
Odourants can reach the olfactory epithelium via two different routes which are…
The nostrils and an opening in the mouth called the nasal pharynx
Where does flavour come from?
Taste and smell triggered through the nasal pharynx
Which gender is more sensitive to odor?
Women
When does the sense of smell decline?
With age
What is one finding that helps to substantiate the theory that olfaction serves one or more special functions related to reproduction?
Women of child bearing age have smell sensitivity which is not present in prepubescent girls or post-menopausal women
Odour figures into the complex stimuli that are involved in attachment between human infants and their mothers. True or false
True
Why would mice choose mates that have the most different smell from them?
- This indicates that the are not likely to be close relatives
- This will add new genetic variation to the mix of disease-fighting cells that develop in offspring
(their smell is associated with genes that determine some cells in the immune system)
How does smell play a role in incest avoidance?
By creating a natural aversion. Those pairings most likely to suffer negative consequences of incest (father-daughter, siblings) have a natural aversion to each others body odour.
What is a pheromone?
A chemical that is released by an animal and that acts on other members of the species to promote some specific behavioural or physiological response.
What is the vomeronasal organ?
A structure found in the nasal cavity of most mammals designed to respond to specific pheromones
Where do human taste receptors exist?
Only in the mouth
Where are receptors for taste found?
In special taste receptor cells (not directly on sensory neurons) which are located on taste buds which are in turn located in spherical structures called fungiform papillae
How many taste buds do most people have?
Between 2000- 10000, located on the tongue, roof of the mouth, and opening to the throat
How is a chemical tasted?
First, it must be dissolved in saliva, then come into contact with the appropriate receptor cell, then, via transduction (action potential) the taste information is carried to the sensory neurons that run to the brain
What are the six primary tastes?
sweet, salty, bitter, sour, umami and fat
Where is the primary taste area located?
In the insula- buried in the central fissure that separates the temporal and parietal lobes
Where does the primary taste area send output to create flavour?
The orbitofrontal cortex
Pain is a somatosense, true or false?
true. It can originate from multiple places throughout they body
Pain is not only a sense but also…
a perception, an emotion, and a drive
What is one example of the evolutionary value of pain?
People born with a genetic condition which prevents them from feeling pain often die young due to tissue deterioration or wound infections
What are the primary neural pathways for pain?
receptor cells are located in sensory neurons, pain neurons are thinner than other neurons from the skin and their sensitive terminals (free nerve endings) can be found in all body tissues from which pain is sensed
What are the two types of pain sensory neurons
- C fibres- thin unmyelinated, slow conducting (respond to all types of pain)
- A-delta fibres- thicker, myelinated, faster-conducting (respond to strong pressue (pin prick) or temperature)
What are the three psychological components of pain?
- Sensory component- (somatosensory cortex) perceive pain and locate it
- Primary emotional and motivational component- (cingulate and insular cortexes) desire to escape pain
- secondary emotional and motivational component- (prefrontal lobe) suffering that derives from worrying about the future and meaning of pain
List one example of pain which does not derive from stimulation of pain receptors
phantom limb pain
What is the gate-control theory of pain?
Melzack and Wall’s theory proposing that pain will be experienced only if the input from peripheral pain neurons passes through a “gate” located at the point that the pain-carrying neurons enter the spinal cord or lower brainstem.
What are two possible evolutionary explanations for pain enhancement?
- to motivate ill individuals to rest rather than move around in order to conserve energy needed to heal/ fight disease
- to motivate individuals to protect damaged areas of their bodies
What is the neural centre for pain inhibition in the midbrain called?
periaqueductal gray (PAG)
Where are endorphins produced in the body
The brain, spinal cord, pituitary and adrenal glands
What is stress-induced analgesia?
The reduced sensitivity to pain that occurs when one is subjected to highly arousing (stressful) conditions (depends partly if not entirely on the release of endorphins)
Which mammals have the keenest hearing?
bats
What is sound?
the vibration of air or some other medium produced by an object
What is amplitude?
The amount of physical energy or force exerted by a physical stimulus at any given moment. For sound, this physical measure is related to the psychological experience of loudness. (decibels- dB)
What is frequency?
For any form of energy that changes in a cyclic or wave-like way, the number of cycles or waves that occur during a standard unit of time. For sound, this physical measure is related to the psychological experience of pitch (Hertz- Hz)
What is pitch?
The quality of the psychological experience (sensation) of a sound that is most related to the frequency of the physical sound stimulus.
What is the frequency range of sounds audible to humans?
20- 20,000 Hz
Hearing evolved out of which other sense?
Touch
What is the outer ear?
The pinna (the visible, external portion of the ear) and the auditory canal (the air-filled opening that extends inward from the pinna to the middle ear).
What is the middle ear?
The air-filled cavity separated from the outer ear by the eardrum; its main structures are three ossicles (tiny bones) that vibrate in response to sound waves and stimulate the inner ear.
What is the inner ear?
The portion of the ear lying farthest inward in the head; it contains the cochlea (for hearing) and the vestibular apparatus (for the sense of balance).
What is the cochlea?
A coiled structure in the inner ear in which the receptor cells for hearing are located.
What is the basilar membrane?
A flexible membrane in the cochlea of the inner ear; the wave-like movement of this structure in response to sound stimulates the receptor cells for hearing.
What are hair cells?
The receptor cells for hearing, which are arranged in rows along the basilar membrane of the cochlea in the inner ear.
What are the two general categories of deafness?
- conduction deafness (ossicles become rigid, helped by conventional hearing aid)
- sensorineural deafness (damage to the hair cell/ auditory neurons, can be helped by cochlear implant if damage is to hair cells)
Where are low, medium, and high frequency sounds perceived along the (uncoiled) cochlea?
High- peak near the oval window (shortest distance)
Medium- peak near the middle of cochlea
Low- peak near distal end (near round window, longest distance)
How do modern cochlear implants code sound frequency and perception of pitch?
By using place (location along cochlea) and timing (frequency of action potentials- higher/ lower pitch).
What does it mean that neurons in the primary auditory cortex are tonotopically organised?
neurons are systematically arranged such that high frequency tones activate neurons at one end of the cortical area and low-frequency tones activate neurons at the other end
How do heredity and experience play a role in hearing?
Heredity determines the general form of the tonotopic map and experience determines the specific amount of cortex devoted to any particular range or frequencies
What other area does the brain use to distinguish pitch?
An area in the parietal lobe of the primary auditory cortex called the intraparietal sulcus (it involves both music perception and visual space perception)
What is a key factor in sound location?
The time at which each sound wave reaches one ear compared to the other
What are phonemes?
The various vowel and consonant sounds that provide the basis for a spoken language
What is phonemic restoration?
An illusion in which people hear phonemes that have been deleted from words or sentences as if they were still there (gap must be filled with noise, cannot be silent)
