Muchado Flashcards
what is a single cell recording?
measures action potentials of an individual neuron
what are event-related potnetials?
when an EEG is taken based on an event, so the person does an event and their brain activity is noted as a response to that event
what is spatial resolution?
how good the imaging is at picking up WHERE in the brain something happens
what is temporal resolution?
how good the imaging is at picking up WHEN the activity happens
which form of brain scan has bad spatial resolution but good temporal resolution?
EEG
what are the 3 types of structural MRI images?
CT, MRI and DTI
what are the 3 types of functional MRI images?
PET and fMRI images
how do CT scans work?
use x-ray to produce many brain images, good for finding changes in structure of the brain due to damage
what are diffusion tensor images (DTI) used for?
images white matter tracts using MRI
what do PET scans capture?
detects radioactive material in the brain
what brain imaging technique has greater spatial resolution than PET scans ?
fMRI
how is sound mapped in the auditory cortex?
tonotopically
what is interaural time?
the slight differences in the arrival time of sound between the two ears, helps with sound localisation
what are cochlear implants used for?
implant doesn’t amplify sound (like hearing aids) but stimulates the spinal ganglia cells with electrical impulses
what are the black, coloured and white parts of the eye called?
black = pupil
coloured = iris
white = scalera
what wavelengths of light are visible to the human eye?
400-700nm
where is the blindspot?
around 15 degrees eccentric of the temporal hemifield
what information crosses from the eye - nasal hemifield or temporal hemifield?
nasal
where does visual information cross?
optic chiasm
what are the three locations that optic information go to?
superior colliculus, thalamus (LGN) and the pretectum
what is the retinotectal pathway?
subcortical vision, from the retina to the SC, 10% of cells send their info here
what is the retinogeniculostriate pathway?
cortical vision, retina, thalamus and primary visual cortex
what is the name of the light flashes caused by TMS to the occipital lobe?
phosphenes
what is the phosphene threshold?
the minimum TMS intensity needed to evoke a phosphene; a lower threshold indicates an increased cortical excitability
do people who take ecstasy have a lowered phosphene threshold and why?
yes, because the drugs make their neurons more excitable - led to more hallucinations
what is the ventriloquist illusion?
the sound source is in sync but is spatially discriminated
what info does the V4 process?
colour and form, in the ventral stream
what info does the V5 process?
motion and speed of motion perception, in the dorsal stream
study on mice with cortical vs subcortical lesions doing localisation and discrimination tasks found that…?
mice with cortical lesion = good at localisation but bad at discriination
mice with subcortical lesion = good at discrimination but bad at localisation
- therefore: cortical damage leads to damage in telling WHAT something is and subcortical damage leads to damage in telling WHERE something was
- was a double dissociation
what is the Sprague effect?
this guy Sprague found that if vision is lost because of cortical damage, their vision can be restored in the blind hemifield by removing the contralesional superior colliculus or by cutting the fibres that connect the two superior colliculi
why does the Sprague effect work?
the vision in the blind area can be restored because removing the SC that is opposite to the damaged area disinhibits the SC that IS on the same side of the blindness, meaning the vision that was blinded can be seen using the SC (alternative pathway), but the subcortical areas that were ipsilesional were impaired
what is blindsight?
where blind people can still see a stimulus (light) in the visual field they are blind to. People can still see it, it is just not conscious to them, because it still activates the retinotectal pathway
what do neurons in the superior colliculus notice?
movements in the contralateral visual fields, with the smallest movements being represented in the upper SC and bigger movements in the lower SC
what area of the brain has a major role in generating rapid eye movements?
superior colliculus
what is reflexive orienting?
being able to quickly react to something that happens in your periphery vision
what is a saccade?
quick movement of the eyes (REM)
what are fixation cells?
cells that fire when a stimulus is fixated on and decreases firing when the fixation point declines; causing the fixation reflex
what is the fixation reflex?
triggered by an external visual stimulus that is present at the fixation point. SC cells are activated and this activation ensures the eyes maintain their position on the fixation point
how are fixation and eye movement an opponent process?
because reflexive saccades help our eyes to move in response to sudden changes in the periphery, but the fixation reflex makes our eyes stay in position (like a blinking contest, someone tries to distract you but you need to focus on keeping your eyes open)
what is the fixation offset effect paradigm?
when a stimulus is present as the fixation point, cells in the rostral SC are activated, then when the fixation point is lost, the firing rate decreases, but also inhibits the saccade cells to stop eye movements
what is the frontal eye field (FEF)?
a region of the brain between the superior frontal sulcus and the precentral sulcus, that receives visual information indirectly, and projects down to the saccade generators (SG) in the brainstem
what does damage to the frontal eye field cause?
delayed voluntary saccades, showing the FEF is associated with voluntary eye movements
endogenous vs exogenous eye movements?
endogenous = voluntary and not dependent on external stimulation
exogenous = depending on external stimulation
why are exogenous saccades faster than voluntary saccades?
exogenous are controlled by brainstem, but voluntary saccades are controlled by the frontal eye field (cortex)
how do infants learn the fixation reflex?
so the idea is that with time babies learn to better control the fixation reflex so they follow stimuli more, to switch from mainly exogenous orientation to endogenous control of eye movements
what is the anti-saccade task?
subjects are required to make a saccadic eye movement away from a target, rather than towards it; requires the inhibition of the reflexive saccade and followed by a voluntary saccade
how does aging affect anti-saccades?
more anti-saccades errors when older so can get more easily distracted
overt vs covert shifts of attention?
overt = actually moving the eyes when you place your attention on something
covert = when something holds your attention without moving your eyes
what is the inhibition of the return idea?
when you react faster to something when it appears as you expect vs when it appears in a location you didn’t expect; this allows us to focus our attention on one thng at a time
what is the Flanker task?
used to see how distracted someone can be, older people make more mistakes with this
what is the prenatal formation of the brain?
cell division, cell migration, cell differentiation
do people who have never seen light before (born blind) still have visual processing abilities/infrastructure in their brains?
yes, visual cortex was still active in blind people, but people used other senses to sense things
how does the human brain respond to training?
when people learnt a new skill, their performance got better as they practiced it and greater amounts of blood flow occurred in the motor cortex when doing trained sequences rather than untrained experiences after only three weeks of training. They also found after 8 weeks without any training; the blood flow rate remained high to retain the learning
