L5 Flashcards
which area of the brain is activated when you are processing colour
V4
what happens when you damage V5
akinetopsia (cant see moving things)
monkeys have a similar area to V5. what is this
MT
describe the cells in V5
these cells respond to movement in different parts of the visual field. some of these cells also respond to the speed of the object
they change their firing rate
what use is motion detection
6
Captures attention
Segments foreground from background. (eg in the car things close to you are moving faster)
Helps in computing the 3D shape of an object.
Allows estimation of the direction in which you are heading within the scene. (optic flow)
Allows recognition of actions
Helps compute the distance to various objects in the scene
what is optic flow
If you fixate on something in the direction that you are moving in the periphery will flow past you. This is called optic flow. The NS uses this to detect what direction you are moving in
what is the definition of looming
change in visual angle as you approach an object
what is looming
Looming is when you get closer to an object that that object rapidly gets bigger in your visual field
This is not a linear relationship
This happen when you fixate on an object that you are walking toward. The object will be the same size until you get really close to it and then it will expand rapidly
what is the binding problem
this is the question of how your brain attaches a particular feature to an object
what is one potential solution to the binding problem
temporal binding
what is temporal binding
Distributed neural responses are tied together by the coordinated timing of their firing patterns.
This synchrony is often associated with repeated, oscillatory activity
Cells firing in synchrony form “cell assemblies” that collectively represent a given object at a moment in time
This shared timing tags specific cells as sharing the same “message” and links the features of an object together
what is proof of temporal binding
ambiguous figures
you can see 2 different images in the same image
the image is not changing which means that infoder for you to see the other image something in your brain must have changed
if you are preceaving thing at different time (temporal binding theory) then how come you still see a whole image and not just the thing you are looking at
being spread out over time does not mean you brain looks at one thing and then it looks at another it means that the pathways in the brain are active at different times
eg you have 2 networks firing in the brain. these are firing at the same time but the pathways have different firing rates meaning that the cell in those networks are not active at the same time
what is schizophrenia
A disorder characterized by abnormalities in perception,
cognition and emotion
what are the +ive symptoms of schizophrenia
hallucinations, delusions
what are the -ive symptoms of schizophrenia
apathy, lack of motivation
what are the cognitive symptoms of schizophrenia
bad memory, disorganised thinking
what are some examples of thought and language disorder in schizophrenia
clang
derailment
word salad
what is clang
inappropriate rhyming
eg “I said the bread and read the shed and fed Ned at the head”
what is derailment
when the statement starts off good but as time goes on the person gets more and more off topic/makes less sense
what is word salad
the extreme form of derailment
what are some risk factors for schizophrenia
Genetic (concordance in monozygotic (identical) twins is 30-40%; dizygotic 5-10%
Older age of father
Complications during pregnancy or at birth
Season of birth (winter and spring)
Urban living
Socioeconomic factors (stress)
Drug use in teens and young adulthood
if you were to look at the brain of a schizophrenic person what would you expect to see
Enlarged ventricles
Reduction in size of several regions including frontal cortex and medial temporal
lobes
Reduction of activity in frontal cortex and medial temporal lobes
Excessive subcortical dopaminergic activity with increased DA release,
synthesis and storage.
Decreased activity in GABAergic, inhibitory systems
Decreased activity at the NMDA subtype of glutamate receptors.
what is the dopamine hypothesis of schizophrenia
that schizophrenia is caused by dopamine
what is some evidence that supports the dopamine hypothesis
Drugs that enhance dopamine (DA) release or effects produce some of the positive effects of schizophrenia in healthy individuals
Dopamine super-sensitivity and elevated dopamine D2 receptors have been reported in patients
Antipsychotic drugs like chlorpromazine block DA receptors
what is the glutamate hypothesis of schizophrenia
Inhibitory neurons modulate excitation via NMDA receptors
(excitatory release glutamate, inhibitory release GABA)
What we think happens in schizophrenia is that we think the GABA receptor (NMDA) is desensitised which reduced the brake on the excitatory neuron
what is some evidence that supports the glutomate hypothesis
Negative and cognitive symptoms are not responsive to dopamine blockade
Antagonists of the NMDA subtype of glutamate receptor, such as ketamine and PCP, produce a psychosis that resembles
schizophrenia and generate the negative and cognitive
symptoms.
Dysfunction may occur where the NMDA receptor is involved in communication between excitatory and inhibitory neurons
what is the difference between when you present a mooney face to a normal brain to a schizophrenic brain
(a mooney face is one of those black and white images that is heart to make out)
you see changes in the way that the brain oscillates
When you present the picture to the control, about 100ms after presented you will see very large and bright gamma bands (high frequency brain oscillations).
In schizophrenic the response is suppressed which suggests that there must be something wrong with the circuits
this is also the same for beta bands but beta band is even lower
what is transcranial magnetic stimulation (TMS)
This is when you put a coil of wire over the top of your skelp which activates the neurons underneath it
which area of the brain has the largest reduction in frequency of oscillations in schizophrenia
the prefrontal cortex
what is the PANSS score
positive and negative syndrome scale
the higher the score the more symptoms you have
what is the relationship between the PANSS score and oscillation frequency
higher the score the lower the frequency
in the prefrontal cortex what did a low frequency relate to
poor memory
in schizophrenic brains, what would you see if you were to look at the hippocampus
you would see (in a scan) that there is less GABA receptor (A5) avalibilty in the hippocampus
