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PSY1202 Introduction to biological psychology > Senses 1 > Flashcards

Flashcards in Senses 1 Deck (48)
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1
Q

what are sense organs?

A

structures containing receptors and interneurons that are specialised for detecting and processing particular types of stimuli

2
Q

mechanical modalities

A

touch

pain

hearing

vestibular

joint

muscle

3
Q

visual modalities

A

seeing

4
Q

thermal modalities

A

cold

warmth

5
Q

chemical modalities

A

smell

taste

common chemical

vomeronasal

6
Q

electrical modalities

A

electroreception

7
Q

touch

A

contact with/deformation of body surface

8
Q

pain

A

tissue damage

9
Q

hearing

A

sound vibrations in air/water

10
Q

vestibular

A

head movement and orientation

11
Q

joint

A

position and movement

12
Q

muscle

A

tension

13
Q

seeing

A

visible radiant energy

14
Q

cold

A

decrease in skin temp

15
Q

warmth

A

increase in skin temp

16
Q

smell

A

odorous substances dissolved in air/water in nasal cavity

17
Q

taste

A

substances in contact with tongue

18
Q

common chemical

A

changes in CO2, pH, osmotic pressure

19
Q

vomeronasal

A

pheromones in air/water

20
Q

electroreception

A

diffs in density of electrical currents

21
Q

what are receptor neurons?

A

are specialised to detect internal and external stimuli of a particular sensory modality, especially when stimuli change

act as filter for stimulus information, transforming stimulus energy in neural signals that are transmitted to sensory interneurons

22
Q

coding in diff sensory modalities

A

all neurons share the same vocabulary of neural signals.

23
Q

first stage in processing sensory info

A

receptor neuron

all in PNS – send info to CNS

taste receptors and sensory interneurons in the tongue

photoreceptor and sensory interneurons in the eye

hair cells and sensory interneurons in the ear

Pacinian corpuscle in the skin

don’t have axons that enter CNS

Olfactory receptor in the nose

sensory receptors and interneurons from each sensory modality project to segregated areas or layers within an area of the brain

24
Q

what other senses do animals rely on?

A

magneto-reception (e.g. birds, reptiles)

polarisation vision (e.g. insects)

electro-sensation (e.g. eels, teleost fish)

echolocation hearing (e.g. bats, whales)

such additional senses require adaptations at the level of receptor neurons and/or in the processing sensory pathways and brain areas

25
Q

what are sensory systems?

A

good examples to demonstrate some of the known fundamental principles of brain organisation and neural network functions.

26
Q

what are mechanoreceptors?

A

touch and pain: Diverse receptors in the skin and body

posture control:
Propioreceptors in the body (muscles, joints)

hearing: Hair cells in the inner ear

balance control: Vestibular receptors in the vestibular apparatus

27
Q

receptive field of a receptor neuron

A

receptive field is the region in space in which stimuli affect that neuron’s firing rate

28
Q

small receptive fields

A

in touch-sensitive receptors: Free nerve endings, Merkel’s disc and Meissner’s corpuscle sense innervate the surface of the skin and are sensitive to stimuli in small areas of the skin

29
Q

large/wide receptive fields

A

Pacinian corpuscles and Ruffini’s endings innervate deeper layers of the skin and are sensitive to stimuli over a larger areas of the skin

30
Q

receptors that transmit signals from skin to spinal cord

A

Pacinian corpuscle (in skin, muscles – detecting vibration and pressure) is a unipolar cell that extends one branch of its axon to skin and other to spinal cord

afferent projections form the dorsal root (spinal) nerve and the cell bodies are part of the dorsal root (spinal) ganglion.

31
Q

mechanically-gated ion channels

A

vibration or pressure on skin deforms the corpuscle and stretches the tip of the axon opening mechanically-gated ion channels.

note the concentric layers of tissue (like in an onion) around the axon tip that amplify the signal

32
Q

receptors with a graded potential

A

similar to the dendrites of a postsynaptic neuron, receptors respond to stimulation with a graded potential, the receptor potential

spiking receptor neurons convert the receptor potential into spikes

33
Q

response thresholds in receptor neurons

A

receptors respond to a stimulus within a range of stimulus intensities.

different types of receptor neurons vary in their response thresholds for the same type of stimulus.

response rates for three different hypothetical types of receptor neurons with different response thresholds.

low threshold fires no matter what

others need a stronger stimulus

34
Q

filtering and coding sensory info

A

sensory systems can combine receptor neurons with different sensitivities (=different thresholds).

this is useful for extending the range of intensities for which they jointly can respond and for distinguishing between different stimuli, if using a combinatorial code.

35
Q

receptor adaptation: adjustment of thresholds over time

A

receptors can adapt (to certain extent) their threshold, if the prevailing range of stimulus intensities changes, to optimise coding of the stimulus.

move threshold to experience lower freq if continuously experiencing lower thresholds and vice versa for high

36
Q

adjustment of receptor response over duration of stimulus

A

a single stimulus is usually not enough to shift the sensitivity of the receptor neuron (response threshold)

after a short break a second stimulus of the same intensity will elicit the same response.

37
Q

slow adapting and small receptive field receptors

A

Merkel’s disc - sensing texture

38
Q

slow adapting and large receptive field receptors

A

Ruffini’s ending - sustained contact

39
Q

fast adapting and small receptive field receptors

A

Messiner’s corpuscle - vibration

40
Q

fast adapting and large receptive field receptors

A

Pacinian corpuscle - initial contact

41
Q

sensory pathways

A

segregated projections to different areas of brainstem, thalamus and cortex (labeled-line principle).

where possible, information about the spatial location of stimuli is preserved by separating projections that come from receptors in different locations.

it is important to know where stimulation occurred in the body (e.g. whether the hand or back was touched) or relative to the body (e.g. whether wind blows into the face or neck).

42
Q

receptive fields of neurons

A

receptive fields can be mapped for neurons in the sensory pathway

43
Q

cortical encoding in form of somatotopic maps

A

primary somatosensory cortex is located in the postcentral gyrus in the parietal lobe of the human brain.

Brodman areas 1,2 and 3a,b

adjacent regions on body are generally encoded in adjacent regions in cortex
(with some curious exceptions)

44
Q

sensory segregation in cortical somatotopic maps

A

fast adapting signals (from Meissner’s and Pacinian corpuscles) and slow adapting signals (from Merkel’s disks and Ruffini’s endings) remain segregated in cortex

information from different skin receptor types is projected into the different Brodman areas

organisation of neurons in columns and layers in the primary somatosensory cortex.

45
Q

experience dependent plastic reorganisation of cortical maps

A

can be very plastic

cortical representations can change with use

Owl monkey trained for several months at task using fingers 2-4

46
Q

suppressing sensory input

A

just as nerve cells need to be inhibited, receptors and the signals they convey also need to be ‘switched off’ at times

often suppression involves accessory organs. Such structures reduce the intensity or alter the stimulus before it reaches the receptor e.g. Eyelids, muscles in ear

or it can be via top-down processes e.g. brain stem sends messages to receptor cells in the ear to selectively dampen sounds

47
Q

phasic receptors

A

receptors that show fast loss of response shortly after onset of stimulation

48
Q

tonic receptors

A

receptors show a slow loss of response