L2 - Sensory Processing Flashcards
What are qualia?
Perceived sensations
What is the explanatory gap?
We can’t explain why we all perceive colours, sounds and smells differently
Define an adequate stimulus
A physical or chemical stimulus that needsthe least energy to change the membrane potential of a sensory nerve cell
Outline the law of specific nerve energies by Müller
The final CNS destination not the type of stimulus determines the quality of perception
Outline Sperry’s experiments on the frog visual system
Severed optical tracts and connected them to the opposite sides to what they were originally. The frogs were confused as the cortical areas were the same as before therefore believed that what it was seeing with it’s right eye it was actually seeing with it’s left. This backs up the law of specific nerve energies
What is the Anes room illusion?
A room designed with forced perspective. This shows us that we are conscious of sensations/percepts not of physical reality
What are the senses for physical stimuli?
Mechanical senses Temperature Vision Electric Magnetoreception
What are the sense for chemical stimuli?
Olfaction
Gustation
What is proprioception?
the position of one’s own body in space
What is interoception?
Sense of the physiological condition of the body e.g. hunger, thirst etc.
What are primary sensors?
They cell detects the stimulus and directly sends an AP
What are secondary sensors?
The cell detects the stimulus which is then passed onto a secondary cell where it is transformed into an AP
What is transduction?
Conversion of a stimulus into a bioelectrical signal
What is transformation?
Conversion of an electrical signal into an AP train
What is conduction?
Passing on of the electrical signal
What are the properties of a sensor potential?
Graded, no threshold Summation possible as no refractory period Usually depolarising Local potential Electrotonic conduction
What is the wave code?
Frequency of an AP dependent on the intensity of the stimulus
Outline the experiment which tested light detection int he Horsehoe Crab compound eye
Increasing light intensity led to increased AP frequency
Increased length of stimulus led to increased length of AP train
The coding of sensory information is encoded via a temporal pattern of a sequence of APs. The analog sensor potential is transformed into a digital representation.
What are the receptor response types and outline them?
Proportional - tonic, static. The sensor encodes the stimulus based on strength
Differential - phasic. The sensor reacts to the speed of the stimulus change
Proportional-Differential response type - Encode stimulus amplitude and convert fast changes into higher AP rates
What is adaptation?
Decrease of tonic response over time to a persistent stimulus
What is habituation?
Decreased reaction of an organism to ongoing or repetitive stimulation
What is a receptive field?
The particular region of the sensory space in which a stimulus will trigger the firing of that neuron
Why overlap receptive fields?
To create a much more complicated receptive field at the cortical level
What is psychophysics?
The scientific study of he relationship between physical stimuli and the perceptions evoked by the stimulus
What are the two types of sensory detection threshold?
Absolute threshold
Just Noticeable Difference (JND)
What is Weber’s Law?
With increasing stimulus intensity R the absolute perceptible difference delta R also increases the relativ eperceptible difference delta R/R is constant
What is the law of Weber-Fechner?
The perceived intensity E is logarithmically dependent on the relative stimulus intensity
Why is the nervous system optimized to detect relative differences?
To adapt to changing environments
What is the psychometric function?
It models the relationship between a given feature of the physical stimulus and the forced choice responses of the subject.
Outline Newsome’s experiment Motion detection in the cortical area MT
A monkey had to detect coherent motion. The physical stimulus intensity was the percentage of coherently moving points. The greater the coherence the greater the firing in one direction detection.
MT = medial temporal area int he visual cortex
