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50 Cards in this Set

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Platonic view of vision and the world?
The 'real world' exists but mortal sense are only capable of sampling a small fraction of it.
Friedrich Nietzsche's view of vision and the world?
There is no real world, only the world inside your head. Vision as construction.
The world that we visually sense is entirely dependent upon...
- our individual perceptions
- light
Excitation refers to...
a state/response due to external stimuli, an application of energy.
Sensation refers to...
the detection of external stimuli by sensory organs.
At what stage in the visual pathway is an action potential first generated?
Ganglion cells
What do L, M & S denote when applied to cones?
Long (red), Medium (green) & Short (blue) wavelengths of light.
Why are photoreceptors anchored to the retina despite there being neural matter between between the light source and receptor?
Inverted retinal neural design, reason for blind-spot.
Protection and insulation of photoreceptors.
Transportation of nutrients.
A colour space is...
an abstract model/representation of colour in space.
e.g. RGB & CYMK
Orthogonality in the vector representation of signal-coding confers which of the following properties upon that stage of the system?
- Orthogonality allows overlapping stimulus-coding.
- Positive and negative interactions
Which statement best describes a receptive field?
Receptive fields are an abstract construction describing the sensitivity of a sensory neuron.
What is the most likely format of the first spatially structured (or differentiated) receptive fields in the visual system?
Centre - Surround organisation. Donut shape.
The receptive field arrangement referred to in Question 12 confers what properties to the system?
The property of opponency.
The term "opponency" refers to...
Theory of opponency records the differences/opposites between colour or stimuli.
Why, when considering the processing of the neural signal, is the actual physical location of any visual neurone other than the photoreceptors, arbitrary?
Information from the receptive fields relate to the same x,y,t space and photoreceptors are the only thing in direct contact with the stimuli. It doesn't matter after that point.
Why, however, is the relative location of any sensory neurone potentially important?
Information (shapes, lines and contours) in the real world has to be represented the same way in the brain.
What is meant by the term "retinotopic mapping"?
Retinotopic map is the topopgraphic map of the retina as represented in the brain. It maintains relative relationship of neurons whilst the actual location is irrelevelant/arbitrary as long as they are in close proximity. (Visual cortex)
What is meant by the term "tonotopic mapping"?
Tonotopic map is the topographic map of the audio input from the cochlea represented in the primary audio cortex of the brain.
The term "phase-coherence" refers to the hypothesis that...
an edge/border is signalled consistently across all scales of analysis.
The idea of modularity in visual processing refers to...
different modules in the brain have differentiated functions.
What reason may you have for questioning the assumption that the LGN is just a relay station fo signals travelling from the retina to the cortex?
There are more neural pathways from the visual cortex to the LGN than from the LGN to the visual cortex.
Taken as a population, primary visual cortical (v1) neurones have what critical property?
V1 cortex (striate) are responsible for representing everything in the raw form. All visual information enters at this point.
- Cortical magnification
- Orientation sensitivity
An example of context-dependency in vision is...
Matchsticks arranged in circles.
Matchsticks arranged in circles.
What is red?
Red is definitive as a specific wavelength but sensation and perception of it differs between individuals.
An attentionally-controlled motion system may...
Attention modulated motion is the isolation of a particular aspect of motion so that we are not overwhelm by input of information.
e.g. Keeping the world still as you move your eyes.
The visual system appears to dissociate motion-signals elicited by eye-movements or from the retinal motion by...
the In-Flow Hypothesis: feedback from the eye-movement.
the Out-Flow Hypothesis: feedback from the commanding signal.
the In-Flow Hypothesis: feedback from the eye-movement.
the Out-Flow Hypothesis: feedback from the commanding signal.
The spatial structure of natural textures is consistent with the properties of the system because...
Receptive fields are more selective to natural textures due to evolution???
"Adaptation" refers to...
reduced sensitivitity to the stimulus as a result of repeated exposure.
What is meant by the term "parallel processing"?
It is the ability of the brain to process information simultaneously.
A form of parallel processing in the auditory system is implemented in the cochlea nucleus by...
Divergence of auditory signals received from the cochlea before its input into the auditory cortex.
One critical similarity between the auditory system and visual system is...
Inputs are both topographically mapped out onto the brain in their respective cortexes.
One critical difference between the auditory system and visual system is...
Visual information is processed contra-laterally whilst auditory information is processed bilaterally.
The terms M and P in the context of the visual system refer to...
two types of LGN cells: Magnocellular (input from Parasol Ganglion cells) and Parvocellular (input from Midget Ganglion cells). Oh the irony.
Information is...
What stimuli is translated into for the brain to process.
A vector is...
Direction + Magnitude. A single directional signal.
The theoretical hierarchy established by David Marr is...
Problem -> Algorithm -> Implementation
"Retino-cortical expansion" refers to...
Cortical expansion. Where there is a larger number of neurones corresponding to the centre of the visual field compared to the peripheral.
Cortical expansion. Where there is a larger number of neurones corresponding to the centre of the visual field compared to the peripheral.
Which of the two structures listed below exploit orthogonality in the representation or operation?
semicircular canals? Orientation receptive fields in V1 cortex.
What computational role does the cochlea play in audition other than simply transduce the auditory signal?
It also has a function in the vestibular system, spatial awareness.
Psychophysics is...
The relationship between a physical stimuli and the sensation and perception they affect.
What aspect of the relationship between the stimulus and the cortical representation is different between vision and audition?
The visual system exhibits some form of cortical magnification whereas the auditory system does now. (Varies a bit but relatively constant)
The two most likely kinds of motion detector in the human visual system are called...
- Delay&Compare/Correspondence/Hassenstein-Reichardt/Fly&Beetle Detector
- Spatiotemporal Gradient Detector
The three critical dimensions of vision are...
X axis, Y axis and time. (x,y,t)
The term "Biological motion" describes...
Movement made by biologically active stimuli. e.g. Stick figures. Dots fit our expectations and fill in gaps of biological movement.
Interaction between V1 orientation-selective receptive fields follow what laws?
Aligned V1 receptive cells positively interact whilst orthogonal receptive cells negatively interact.
Aligned V1 receptive cells positively interact whilst orthogonal receptive cells negatively interact.
The visual system is sensitive to...
The visual wavelengths of 380 - 760?
What critical neural interaction is affected by hallucinogenic drugs?
Affects neurotransmitter receptors, particularly serotonin. Disrupts action potentials and signalling.
Your experience of reality is...
Subjective and individual.
Synaesthesia is...
a cross wiring of different senses.
One fish, two fish,...
Red fish, blue fish.