Module one - Bilkey Flashcards
what regulates the body’s internal environment?
autonomic nervous system
what system interacts with the external environment?
somatic nervous system
what is the charge of the inside of a neuron
-70mV
what is a concentration gradient?
difference in the concentration of a substance from the outside of the membrane to the inside.
what is depolarisation?
an electrical state whereby the inside of the cell is made less negative to the outside than at the resting membrane potential.
what is a graded potential?
they are like an electrical signal that is initiated by a weak or strong stimulus; they begin in the dendrites and cel; body.
action potential
the pulse is all or nothing. once it gets to a certain point it goes and the size of the potential doesn’t change.
What happens when we depolarise the membrane
it is more likely other channels will open.
What happens when more channels open due to depolarisation
potassium channels will open that balances the outside and inside of the membrane
What speeds up reaction time?
myelin.
three primary retina cells
ganglion cells, middle layer, receptor cells.
where are rods and cones
receptor cells of the retina.
cones
photopic (colour) vision
rods
scotopic vision-less colour, allow us to see in low levels.
distribution of rods and cones
rods are evenly distributed with lower levels at the centre of the fovea. cones are high at the centre of the fovea but really low levels outside of that range.
what other cells are sensitive to light
intrinsically photosensitive retinal ganglion cells - sensitive to blue light.
the blind spot
where the optic nerve is - there are no photoreceptors there. however we can still see because our brain is constantly processing information and filling in the blanks.
lateral inhibition
creates illusions with our vision. the horizontal cells activate and makes some things seem darker or lighter depending on what is surrounding them.
Mach bands
dark colours will have a dark strip on the edge when they are placed next to a lighter colour - this enhances contrast and tells us where the edge of an object is.
colour cones we have
red, green, blue. red and green (yellow) compete with blue.
opponent processes with colour vision
if you are presented with an image in a particular colour the cells will initially fire strongly but then start to adapt and firing rate will drop off.
the ability to compete with other neurons then decreases.
then we get a rebound of opposing receptors showing a different colour.
approach-avoidance
conflict that results from having to choose between the drive to pursue a reward and to avoid harm.
response of cells in LGN
they respond to information in different parts of our visual field and is active when light hits the cell.
response of cells in V1 (simple cells)
light must be presented in a particular orientation across the certain part of the cell.
response of cells in V1 (complex cells)
light must be presented in a particular orientation but it doesn’t matter where on the cells the light hits.
is mapping evenly distributed?
no, we have higher resolution in our foveal vision.
why is our vision topographical
reduce axon volume and facilitated processing (lateral inhibition)
where are pressure waves of sound converted to electrical currents
cochlea
what do our inner hair cells do?
more vibrations which cause ion channels to open that produced electric currents.
what do we hear at the start of the cochlea vs the end.
start is high frequency and gets lower and lower.
what does the medial geniculate do?
draws our attention to certain sounds. for example sounds off to the side that then grasps our attention.
what happens to sound we hear that our own body is creating?
is it subtracted from our hearing, this is why we don’t often know if we are chewing loudly or notice the sound of our own breathing.
why is our auditory system tonotopic?
reduced axon length, facilitates processing, allows sounds to be encoded, scene analysis, detection of beat (this promotes social cohesion)
what is top down processing
where information that we have influence and how we understand information the comes from sensory systems.
what is the influence of top down processing on our auditory system
use prior information to make predictions about what we will then see or hear. this allows our system to respond rapidly.
dorsal stream
object location in relation to the body. information going to the body.
ventral stream
what an object is. information coming in
what part of the brain are cells that fire to objects located in our visual system found?
inferotemporal cortex.
what people produce the highest firing rate?
people we know in the current context, then friends and family, then famous, then non-famous people.
what is invariance in relation to detecting objects
encoding a representation so that is it identified regardless of size, orientation, colour etc.
what are grandmother cells?
they are cells that represent one certain thing.
problems with grandmother cells
huge number of neurons needed, susceptible to damage, we have to have vacant cells for new objects that use energy, and probability of detecting certain cells is low.
ensemble, population or distributed coding
there are cells that respond to aspects of the person/object. its all these cells firing in a pattern that represent an object etc.
sparse vs. distributed coding
only a few cells vs. multiple cells active.
critical goals of visual information processing
complete patterns, separate patterns, generalisation
pareidolia
is where we complete patterns so much and see them where there aren’t any (seeing faces in objects).
generalisation
helps us to recognise parts of an object or the object from a different orientation/angle.
what critical goals relate to sparse representation
pattern separation
what critical goals relate to distributed representation
pattern completion and generalisation.
how do we identify faces?
by identifying landmarks on the face 25 of which have been noted as ones that produce the greatest variance.
what does knowing which cells are detecting what in faces mean?
it means we can predict what something is looking at based on its neuron activity.
what accounts for the greatest variation in faces
a combination of features together.
what area of the brain is related
V4
what area of the brain is related to movement
V5.
whats happening in the visual system of the brain
lots of parts are firing together and joining the image.
what is looming
that it’s not until we get quite close to an object that is starts to get bigger in our visual field (indicating it is getting closer)
what part of the brain does orientation
V1.
what does the IT cortex do?
where we start to get representations of shape.
temporal binding
distributed neural responses tied together by coordinated timing of their firing patterns.
schizophrenia and binding
there is evidence to suggest those with schizophrenia have trouble with binding.
two hypotheses of why schizophrenia may occur
dopamine hypothesis (positive symptoms) and glutamate hypothesis (negative and cognitive symptoms)
what is the glutamate hypothesis
our excretory neurons are making other neurons too excited which makes them send messages to shut down so there is a constant loop of excitement and shutting down that acts like a pulse.
Mooney face
in control subjects there is a stronger and faster response than those with schizophrenia.
what band in lower in those with schizophrenia
gamma band.
how do we remember an experience
there is a pattern of cell activity that occurs that corresponds to an experience.
how do we remember short term?
by recalling the same pattern of cells that were firing when the event actually happened.
how do we remember things in the long-term?
with strengthened synapses, cells don’t need to be firing all the time but can be activated usually with a sensory cue.
when is a synaptic cell strengthened vs. not
when the postsynaptic and presynaptic cells fire together
long-term alterations in strength of synapses.
over time, after repeated stimulation more receptors are built and placed in the synapse meaning there is much larger potential
what prevents memory formation?
blocking LTP (this can be done with a drug)
what produces forgetting
the reversal of LTP (done with the drug ZIP. rats in a spinning thing not going into a particular section of it)
what can we do that leads to LTP like changes
learn, shown by rats learning new tasks.
what does motor learning produce?
branch specific spine formation. some spines are created and some disappear because they are no longer useful.