Topic 2 - Cognitive Neuroscience Flashcards
VEP
visual evoked potential
Which machine produces VEP? How?
electroencephalography EEG
—> ERP (event related potential)
—-> VEP
By focusing on the object of interest, the VEP acts as a way of
confirming your selection. Evokes a large potential when focusing.
For individuals with severe communication problems, this is potentially a way of communicating via the eyes alone.
A patient in a vegetative state (‘locked-in’) as a result of a road traffic accident was asked to imagine playing tennis and imagine walking round their house. Differential brain activity was produced.
SMA
PMC
PPC
PPA
SMA =
PMC =
PPC =
PPA =
SMA = supplementary motor area PMC = premotor cortex PPC = posterior parietal-lobe PPA = parahippocampal gyrus
What was the difference i brain avit5ivty between a normal person and the person locked in vegetable state?
Normal controls’ brain activity was “indistinguishable” (p. 1402) from the activity of the locked-in patient.
Normal controls’ brain activity was “indistinguishable” (p. 1402) from the activity of the locked-in patient. Therfore?
this evidence of conscious awareness in an unconscious individual?
Parts of the neuron
- dentrites
- soma
- axon
- terminal button
- synapse
- dentrites
- soma
- axon
- terminal button
- synapse
FUNCTIONS ???
DENDRITE
Absorbs chemical stimulation from other neurons
SOMA
If dendritic activity is large enough an electric action potential will be fired
AXON
Conducts the electrical signal to terminal buttons at the end of the axon
TERMINAL BUTTON
Turns the electrical signal back into a chemical squirt
SYNAPE
The jump the chemical has to made to be taken up by the next dendrite
By attaching microelectrodes to _______, we are able to observe ..
AXONS, we are able to observe individual action potentials rather than large ensemble activity.
The whole process of going from baseline, to depolarization, repolarization, refractory period back to resting state takes about
5 ms.
What are the phases of an action potential?
Baseline (-70) Depolarization (+40) Repolarization (-70) Refractory period (below -70) Resting state (-70)
Does the magnitude of the AP change with function of sensory input?
NO, the magnitude stays exactly the same, the frequency that the AP are fired at does change as a function of sensory input.
Differences in the sensory environment are coded by
changes in the rate of axon firing
FEATURE DETECTORS
Types
Simple cells
Complex cells
End-stopped cells
Simple cells
respond to size, orientation, colour
Complex cells
respond to orientation and direction
End-stopped cells
respond to orientation, direction and size
cats were only exposed to light in a vertically stripped cylinder for 5 hours a day. Wat were their neurons responses?
neurons were only responsive to orientations they had previously been exposed to. These cats were essentially ‘blind’ to vertical and oblique lines.
exposed cats from birth to horizontal lines in one eye and vertical lines in the other eye.
What were thier neurons responses?
Single cell recordings revealed very specific neural sensitivity. Neurons had not generalised to oblique orientations, nor to orientations that the other eye had learnt.
Depending on how neurons connect and talk to one another, a form of _______________ arises.
hierarchical processing
hierarchical processing
This is where more and more complex
combinations of information can be
represented
Groups of neurons in the temporal lobe help to code specific examples of
stimuli in the environment. Visual faces, auditory frequencies, olfactory odours might all be sparsely coded.
Dorsal and ventral spans across where of the brain
From bottom to top of the entire head/brain
Lateral and medial spans across where of the brain
From left to right sides of the brain/head
Anterior and posterior spans across where of the brain
Form front to back of the brain/head
What are the three main portions of the brain?
Forebrain
Midbrain
Hindbrain
FOREBRAIN
- Hypothalamus involved in hormone release and appetite.
- Limbic system includes amygdala and hippocampus.
MIDBRAIN
Includes reticular activation system, which controls consciousness, heartbeat…
HINDBRAIN
Basic biological functions controlled here such as swallowing and digestion.
Cerebral cortex is made of what
4 lobes
Which lobes compose the cerebral cortex?
Frontal
Temporal
Parietal
Occipital
Frontal lobe function
information coordination
- personality
- executive decisions
- memory of current events
Temporal lobe functions?
AUDITORY PROCESSING
- connected with first stage of auditory processing
- sparsely code sensory objects
Parietal lobe functions?
Touch, temperature, and pain
- houses the somatosensory homunculus.
- body is mapped out spatially
- stimulation of parietal = specific sensory experiences
Primary somatosensory cortex
Organizes how the Brian mapped out the body.
- organizes the primary motor cortex
What organizes the primary motor cortex?
Primary somatosensory cortex
Which lobe contains the somatosensory homonculus ?
Parietal lobe
Individuals can experience a
‘phantom limb’, that is, experience perceptual sensations of a limb that has been amputated. This might be
due to residual neuronal firing in
certain areas of
primary somatosensory cortex.
One intriguing observation is that in
individuals who have lost an arm,
stroking the face can …
Explain?
reinstate tactile sensation in the arm.
This relates to the organisation of primary somatosensory cortex, and the idea that the face might have ‘moved into’ the empty cortical real estate left by the arm.
Occipital lobe functions
Visual processing
Visual agnosia
Inability to recognize faces or objects
What part becomes excited when seeing something recognizable with visual agnosia,
Fusiform face area FFA
Where is the basic face processing occur?
In the temporal lobe
Where does evaluation of attractiveness occur?
Frontal lobe
Emotional reaction inside occurs where?
Temporal lobe
Basic visual features are processed where in the brain?
Occipital lobe
Awareness of gaze direction occurs where?
Parietal lobes
The corpus callosum is responsible for
transferring information from left and right hemispheres
Transmission across the corpus callosum takes around
1 ms.
Damage to the corpus collusion results in
Split brain
Split Brian
- can be present at birth or form surgery to reduce epileptic symptomology.
Anna today evidence suggests that the two hemispheres may have
2 seperate consciousness
Damage to the right hemisphere?
Left side of visual field Left side control Emotion (?) Creativity (?) Holistic (?)
Damage to the left hemisphere?
Right side of visual field Right side control Language (?) Mathematics (?) Analytic (?)
Our brain is crossed in a peculiar way: information to the right of fixation will be processed by the
left side of both retina, and then, information from both eyes will merge in the left hemisphere.
Damage to LEFT HEMISPHERE Neglect of ____
Damage to RIGHT HEMISPHERE
Neglect of ____
Damage to LEFT HEMISPHERE Neglect of RIGHT VISUAL FIELD
Damage to RIGHT HEMISPHERE Neglect of LEFT VISUAL FIELD
Damage to which hemisphere impacts language ability on which visual side?
Damage of the right hemisphere impairs left visual field
Damage to the left hemisphere impairs right visual field.
Damage to which hemisphere impacts motor based responding ability
Damage to the right hemisphere impairs left visual field and retrieval with left hand is impaired.
Damage to the left hemisphere impairs right visual field and retrieval with right hand is impaired.
Phineas cage case
- Impaired benevolence and agreeableness
- personality changes
Aphasia can be both
Non-fluent —> brochas aphasia
Fluent —> wernickes aphasia
Brochas aphasia
Non-fluent
- impairs expressive language
- brocha’s area located in the left frontal lobe, Near the front of the brain.
- words uttered are slow and poorly articulated.
Wernickes’s aphasia
Fluent
- impairs receptive speech and language (don’t understand words)
- wernick’s area located in the temporal lobe of the dominant hemisphere.
Where does object identification occur?
Temporal lobe
Where do emotional responses occur?
Amygdala
Where’s the amygdala located
In the medial temporal lobe.
Does lesion to a section of the brain and it effecting a specific function mean that that area is responsible for that specific function?
No because u may have just lesioned a communication link instead, effecting a specific function or behaviour, doesn’t necessarily mean its directly responsible for that specific function.
Brain scanning processes
TMS
ERP
PET
MRI
TMS
TRANSCRANIAL MAGNETIC STIMULATION .
Sends weak magnetic fields across the cortical surface, leading to temporary (non-permanent) disruption of electrical activity.
ERP
EVENT-RELATED POTENTIALS
Records the weak electrical fields generated by large scale neural ensembles that permeate out through the skull.
PET
POSITRON EMISSION TOPOGRAPHY
After ingestion of a radioactive tag which attached itself to glucose, glucose uptake related to increased brain activity
MRI
MAGNETIC RESONANCE IMAGING
Records BOLD signal on the principle that oxygenated blood has different magnetic properties than deoxygenated blood.
Pros and cons to TMS
PRO: Relatively safe way of simulating lesions
CON: Effects are not long-lasting, not for epileptic samples
Pros and cones to ERP
PRO: Incredibly precise temporal recording (millisecond)
CON: Spatially diffuse, what does no ERP modulation mean?
Pros and cons to PET
PRO: Allows for insights into functionality of brain regions
CON: Poor spatial resolution, involve radioactive substances
Pros and cons to MRI
PRO: (functional)MRI popular in revealing brain networks
CON: BOLD signal very slow, not sure what it really means
More neuroimaging techniques work on the compromise between
temporal resolution and spatial resolution
Naturally occurring lesions that we ‘find’ are often the most interesting cases, but lack control and are often incredibly
diffuse in terms of affected brain regions.
