Bilkey Flashcards
how many pairs of spinal nerves do we have?
31
how many cranial nerves do we have?
12
what is a sensory dermatome?
an image that describes where the sensory nerves synapse in the spinal cord
what are the two divisions of the forebrain?
telencephalon and diencephalon
are there more neurons lower in the neocortex or less?
less; there are less individual neurons lower in the neocortex and more nerve fibres that form
what are the ion concentrations of sodium and potassium of a neuron cell?
positive charge OUTSIDE the neuron and negative charge INSIDE the neuron
what does the Hodgkin/Huxley cycle describe?
that if an EPSP depolarises a nerve cell, more channels will be opened leading to larger depolarization of the nerve cell to create a positive feedback loop
what axon-related dysfunction is related to multiple schelorsis?
demyelination of nerve axons
do rods or cones have high acuity?
cones
which photoreceptor is more highly concentrated on the fovea?
cones
what is the fovea?
the spot on the retina where light hits when we focus on an object
what is another name for the high acuity vision cones have?
phototopic vision
what is another name for the low acuity vision cones have?
scotopic vision
what does it mean for rods to have a lower visual acuity?
they can be activated by lower light levels
why can rods work at nighttime but cones can’t?
because cones require higher light levels that are not there at nighttime, rods do not require this high light stimulation
why is the stuff we see in our periphery blurry?
because rods are concentrated on the peripheral retina which have a low visual acuity
which form of photoreceptor tends to activate a small number of bipolar cells?
cones
which photoreceptor is better at amplifying their information to many retinal ganglia cells?
rods
what are the 2 types of photoreceptors?
rods and cones
what is spatial frequency?
how detailed an image is based on how much light is sensed
what is high spatial frequency?
when an image has higher details (more specific) but less colours
what is low spatial frequency?
when an image has less details but more colour
why does Mona Lisa seem like she is smiling and not smiling at the same time?
because at a high resolution, she is not smiling (fovea) but our peripheral cells notice the lower resolution in which she is smiling
what area of the retina allows us to see high spatial resolutions?
fovea
what are intrinsically photoreceptive retinal ganglia cells (ipRGC)?
specialised retinal ganglia cells which also notice light, more dominantly blue light by using melanopsin photopigment
where do ipRGC transduce their information?
to the SCN to help govern the sleep/wake cycle
where in the retina are ipRGC found?
bottom, front
what colour light is dominant in the early morning?
blue (hence use of ipRGC to djust our sleep/wake cycles)
what neurotransmitter do RGC’s and photo transmitters mainly release?
glutamate (depolarisation)
what neurotransmitter do bipolar cells mainly release?
GABA (hyperpolarisation)
what is lateral inhibition?
the phenomenon where a neuron’s response to a stimulus is inhibited by a neighbouring stimulus
why does lateral inhibition occur?
because images that receive brighter light in the periphery will activate more inhibitory horizontal cells which makes the image seem dimmer compared to the one next to it
what is an opponent process?
when there are two systems competing to represent the world, for example:
- off/on centres of receptive fields
- approach-avoidance conflict
- homeostasis
- lateral inhibition
how do Mach bands demonstrate opponent processing?
the bands that form do not exist, but because the dark and light colours are placed next to each other, the left side seems darker and the right seems lighter
what is the frequency of purple light?
400nm
what is the frequency of red light?
700nm
is red light or purple light a higher frequency?
purple
what are the 3 main types of cones?
blue, green, red
what is deuteranomaly?
colour blindness weak in green perception (most common)
what is protanopia?
colour blindness weak in red perception
what are the two opponent systems of colour?
red-green and blue-yellow
what are the 5 examples of opponent processing Bilket discussed?
- simultaneous contrast
- Mach bands
- colour perception
- homeostasis
- motivation
where do most of the neurons in the retina send through axons?
to the lateral geniculate nucleus (LGN)
what is retinotopic mapping?
idea that the way we see the world is also organised in how the information is understood in the brain
what is the main difference between simple and complex cells found in the V1?
simple cells have on/off areas where they only respond if light hits them a certain way but complex cells will respond if light falls on them at any area
what is meant by the columnar architecture of V1?
that the cells are close to each other in V1 are responsible for transmitting information about the same region of a visual field
why is the LGN topographically represented?
reduces axon volume which reduces overall brain volume
where do most auditory stimuli travel through before reaching the primary auditory cotex in the brain?
the medial geniculate nucleus (MGN)
what is top-down processing vs bottom-up?
when you use prior knowledge and experience to help you understand the world and novel experiences, bottom-up is using the new information to better understand the world
do humans do more top-down or bottom-up processing in our visual system?
top-down processing
why do humans do more top-down processing than monkeys?
because humans have more brain tissue dedicated in the surrounding tissues of the auditory system, not in the actual primary auditory cortex (like monkeys)
what is the McGurk effect?
that we will perceive an audible stimulus using visual information (‘ba’ and ‘va’ experiment)
what does the dorsal stream from V1 share information about?
the movement of an object
what does the ventral stream share information about?
the object’s features: shape, colour, size
what did researchers learn about facial recognition in monkeys a long time ago?
that they have specific neurons in their IT that fire at different points of a monkey’s head turning
what was the method of the Quironga study about Jennifer Aniston cells?
showed people 100 images and recorded how their V1 neurons fired in response to these images
what were the results from the Quironga study about Jennifer Aniston cells?
- invariance: that the cells fired despite how the image of Jennifer Aniston was changed
- local coding theory
what is the local coding theory?
that a small number of cells in the V1 fire and give you the perception and recognition of an object eg Jennifer Aniston
what are the advantages and disadvantages of the local coding theory?
adv: means the neurones are separated so they don’t mix up the people you see
disad: it doesn’t support the idea of object generalisability or pattern completion
what is pareidolia?
seeing faces in inanimate objects
what is the dense encoding theory?
that many cells have components of the representation of something and the pattern of firing is unique to each situation
what did Doris Tsao find in her experiments of facial recognition?
the main points that make up a face are processed by specific V1 neurons, and the firing sequence of these neurons leads to the recognition of faces
what does V5 process?
movement
what does V4 process?
colour and form
what is akinetopsia?
not seeing movements as fluid movements, but as many still images (Patient MP)
why is it beneficial we can see motion?
- captures attention
- separates back from front
- distance from objects
- 3d shape of an object
- recognition of objects
what is looming?
when you detect a change in an object as you get closer to the object (truck thing)
what is the binding problem?
the problem the brain faces in representing different elements of an image in different areas of the brain, but somehow still is able to make all the information merge into one representation