5 systems and their receptors
- sight=visual=photoreceptors
- touch=somatosensory=specialized endings and free nerve endings
- smell=olfactory=olfactory receptors
- taste=gustatory=taste receptors
- hearing=auditory= hair cells
function of our sensory systems
give an organism information about the external world - and the organism’s internal state
general pathway sensory information through the brain
receptors–>thalamus–>primary sensory cortex–>secondary sensory cortex –>association cortex
transduction
- taking the signal from the environment and transforming it into neuronal activity (a signal our system can understand )
- So receptor cells must have ways that the physical stimulus they detect opens or closes ion channels, changing the membrane potential
4 types of information about a stimulus that are encoded by the nervous system
- modality - the type of info encoded by the receptor
- intensity - the size of thee stimulus
- duration - how long the stimulus continues
- location - where the information comes from
sensation
bottom-up process by which the physical sensory system receives and represents stimuli at the very basic level of sensory receptors and works up
-info coming from our receptors and traveling up the pathway through the brain
perception
Top-down mental process of organizing and interpreting sensory input from experience and expectations
-organizing input and making an experience
how do auditory hair cells work
- convert sound energy to neural impulses and send them along to the pathway to auditory cortex
- mounted in the basilar membrane
- mechanoreceptors such that shearing of the two membranes causes physical deflection of the cilia which opens or closes ion channels
how are the cochlea and primary auditory cortex organized
cochlea–> hair cells activated by sound, which gets translated into AP–>auditory nerve–>thalamus –> primary auditory cortex
does damage to auditory cortex cause deafness
Deafness is usually associated with damage to the ossicles, cochlea or auditory nerve
how does the brain calculate where a sound is coming from
Location is calculated using arrival time and volume differences between the 2 ears.
what are the functions of the olfactory and gustatory systems
- olfactory= smell; detects airborne chemicals
- gustatory = taste; responds to chemicals in the mouth
how does an olfactory receptor work
Each olfactory receptor responds to more than one chemical or odor
how does the brain encode the identity of an odor
through the pattern of activity of many neurons
what is unusual about the olfactory pathway
-does not go through the thalamus on its way to primary olfactory cortex
neural pathway of the gustatory pathway
-taste receptors–>thalamus–>primary gustatory cortex
how do we sense different types of tastes (including hot)? what are the different mechanisms for sensing
-Five primary tastes
◦ Sweet, Salty, Sour, Bitter, and Umami
- Salty and sour don’t have receptors, they merely act on ion channels directly
- Taste receptors are individually variable, continually replaced, and decline with age
- Heat like jalepenos (capsaicin) not detected by taste receptors, but pain receptors
how does satiation change activity in the brain in the gustatory system
- repeated presentation decreases the taste and how more we want with time
- activity decline with increasing presentation of the chocolate bc habituation is occurring so it does not activate gustatory cortex as much
anosmia
-inability to smell
3 somatosensory systems
- exteroreceptive
- proprioceptive
- interoceptive
what do somatosensory receptors respond to
- exteroreceptive: touch/pressure (mechanical stimuli); temperature (thermal stimuli); pain
- proprioceptive : body position
- interoceptive: body condition (temp and blood pressure )
ageusia
-inability to taste
how is the somatosensory system organized
-Different types of receptors detect different types of somatosensory stimuli
- some respond to pressure
- some to being squish
what does the homunculus tell us about the somatosensory system
a representation of the size of representation of the various size of our touch receptors
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Chapter 16
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Chapter 238
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Chapter 2 part 242
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chapter 328
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chapter 411
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chapter 540
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Chapter 6 Object Recognition24
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8: Control of Action29
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9: Memory Part 137
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9: Memory part 225
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7: Attention22
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Chapter 10 Emotions22
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12- cognitive control14
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13- Social Cognition17
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14- Consciousness19
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11-Language21
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12 SOCIAL COGNITION DEVELOPMENT32
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Onishi and Baillargeon 20053
