midterm 1 Flashcards
Phrenology
studying the shape of heads in the belief that they reflect personality
neuron
basic unit of the brain, needs oxygen or dies, has cell body, axon, dendrite
cerebellum
in ventral posterior of brain, controls motor function
equipotentiality
mass action, all actors can do the same things
seizure
sudden electrical disturbance in brain
Jacksonian march
seizure “marches” down the body, limited affect
somatotopy
specific part of brain connects to specific part of body
Broca’s/Wernicke’s area and aphasias
Broca’s aphasia means that the person knows what to say but can’t get it out. Wernicke is basically like word salad
animal lesion experiment
Flourens found that cerebellum lesions caused uncontrolled movement rather than amativeness
brain stimulation experiment
the guy in the bed saw the doctor’s face distorting under electrical stim
craniotomy
surgical removal of skull to expose brain
neuropsychology/neurophysiology
study of behavioral modifications from brain trauma or mental condition/study of central nervous system
anterior
front of brain, also known as rostral
frontal lobe
‘control panel’ of personality and ability to communicate
posterior
back of brain/caudal
cerebral hemisphere
The cerebral hemisphere is one half of the cerebrum, the part of the brain that controls muscle functions and also controls speech, thought, emotions, reading, writing, and learning. The right hemisphere controls the muscles on the left side of the body, and the left hemisphere controls the muscles on the right side of the body.
stroke
the brain loses blood and can cause brain damage
diencephalon/thalamus
deep in brain+link to endocrine system, contains thalamus and hypothalamus/relays messages between brain and body
cortex
outer layer of cerebrum, contains lots of gray matter
hippocampus
located in medial temporal lobe. controls memory, part of limbic system
gray matter and white matter
gray matter are neuron cell bodies, gray from the glia
white matter are axons, white from myelin
glial cell
glial cells regulate neuron functioning
cell body of neuron
connects to dendrites and axon
dendrites
conduct electrical messages to cell body
myelin
insulates axons and enhances their transmission
corpus callosum
interconnects the cerebrum with the diencephalon - integrative
ventricle
there are four of them, contain CSF, provides nutrition to brain
axon hillock/action potential process
contains voltage-gated Na+ channels, opening them depolarizes axon, continues along axon via successive Na+ channels, then axon is repolarized by K+, hyperpolarized by P+, Na/K pump maintains high resting potential
step by step membrane action potential:
1) pumps maintain high rest potential
2) membrane potential depolarized by incoming signals
3) signal repolarized by K+ channels
4) action potential propagates along axon by activating sequential Na+ channels
5) resting potential reached again by action of Na and K pumps
depolarize
low action potential, occurs through the opening of Na+ channels in the AH and this continues along axon
synapse/synaptic cleft
synaptic cleft transports neurotransmitters from one synapse to another.
synapses connect neurons basically
excitatory neurotransmitter/glutamate
pyramidal neurons are usually excitatory, release glutamate onto AMPA receptor
if a ligand-gated channel lets in positive ions like Na+, it’s excitatory and will cause depolarization of post-synaptic neuron
inhibitory neurotransmitter/GABA/inhibitory interneuron
inhibitory interneurons release GABA onto various GABA receptors
if a ligand-gated channel lets in negative ions like Cl-, it’s inhibitory and will cause hyperpolarization of post-synaptic neuron
hyperpolarization
axons are hyperpolarized by voltage-gated P+, and the Na+ pumps maintain a hyperpolarized resting potential
reuptake
neurotransmitters are absorbed back from the synapse into the pre-synaptic neuron
local field potential
Summed electric potentials from multiple (thousands) of neurons near an electrode)
laminar /layering of cortex
Different layers (from 1 - 6, or superficial to deep) are defined by •Different connectivity •Feedforward comes in Layer 4 •Feedback comes in at Layer 1 •Different density of cells •Some layers have more cell bodies, some more axons •Different kind of cells •Pyramidal neurons in layer 4 •Other kinds in different layers
horizontal/coronal/sagittal plane
sunglasses/headphones/ between eyes to the back of head
oscillations and synchrony
correlated input increases spike probability, uncorrelated reduces
effective phase relation increases, ineffective reduces
rostral/caudal
front/back
dorsal/ventral
top/bottom
Electricorticography
records electrical activity from cerebral cortex
visual field
part of the world we can see - visible light
fovea
point of focus - highest acuity - most cones
scotoma
area of bad vision within a field of good vision
optic nerve/optic chiasm
connects brain to eye/the point where optic nerves cross
retina
layer of photoreceptors(rods+cones) that convert wavelengths of light to electrical changes
retinal ganglion cells interpret to the brain
bipolar cells integrate activity of these
retinal ganglion cells
can be on and off-center, 1.5m of them vs 16m cones, on center are responsible for edge detection
interpret retina -> brain
retinotopy(retinotopic organization)
mapping between retina and neurons
cortical magnification/feature detection/orientation selectivity
80% of cortex V1 is dedicated to retina(ie. fovea)/
different cells fire depending on orientation
laminar organization of V1
IV is the primary input layer with ocular dominance columns
Electroencephalography (EEG)
summed electirc potential from millions of neurons, has great temporal resolution but poor spatial resolution
Transcranial magnetic stimulation (TMS)
short magnetic pulse can depolarize neurons close to skull surface and cause them to fire
alpha oscillations/phosphenes
Alpha oscillations modulate phosphene perception •Alpha amplitude reflects the “excitability” of early visual cortex
basilar membrane
converts vibration into electrical signal via hair cells mechanically opening ion channels
tympanic membrane
the eardrum, receives air pressure waves from outside and causes vibration first step
ossicles
connect tympanic membrane and cochlea
cochlea
has fluid which vibrates to distort different parts of basilar membrane
ganglion
a structure containing a number of nerve cell bodies
auditory nerve
its neurons are triggered by the basilar membrane’s hair cells, they then synapse into the brainstem, then the medial geniculate nucleus, then the primary auditory cortex
place code and rate code
where the basilar membrane is stimulated and how frequently the neurons of the auditory nerve fire to represent sounds in the brain
fourier transform
mathematical thing to describe spectral decomposition
interaural intensity difference (IID) and interaural timing difference (ITD)
Interaural timing difference (ITD): the difference in when a signal arrives to each ear
•Interaural intensity difference (IPD): the difference in the intensity of a signal at each ear, caused by the heads ‘acoustic shadow’
tonotopy
in the primary auditory cortex V1 different layers are linked to different frequency (Hz)
somatosensation
Somatosensation really encompasses: •Mechanoreceptors: cells that detect touch/pressure/vibration of the skin
•Nociceptors (pain): cells that detect tissue damage/extreme temperature
•Thermoreceptors: cells that detect ranges of temperature
•Proprioceptors: cells that detect how much different muscles in the body are stretched/relaxed
damage to temporal and parietal cortex
Damage to temporal cortex impacts a task the requires identifying objects, but not identifying relative spatial locations
•Damage to parietal cortex impacts a task the requires identifying relative spatial locations, but not identifying objects (that much)
Dual streams hypothesis
Dorsal visual pathway involved in recognizing where objects are and how to interact with them
•Ventral visual stream more involved in recognizing objects on the basis of shape, texture, color, detail, etc…
•Supported by later work with human lesion patients
visual agnosia
Damage to inferior temporal and inferior occipital brain areas •Developed visual agnosia (inability to recognize objects!)
dorsal and ventral visual pathway
Dorsal and Ventral pathwayV1 —> V2 —> MT —> MST —> PPC
V1 —> V2 —> V4 —> IT•The circuits are even way more complicated than this! •Feedback at every stage •Loops to the thalamus at every stage!
object recognition in IT
•Highly dependent on stimulus but not location (i.e., location-invariant)•Many are also size invariant•Huge receptive fields (~10 to 30 degrees)
hierarchical feature combination/grandmother cell theory
This would mean that every new percept would rely on a new neuron at the top of the hierarchy2.How would the brain “know” how many neurons to allocate?3.Removing one neuron would mean I can no longer recognize my grandmother
combination coding or reduction method
Show real objects to a monkey while recording from IT •Find the object and viewpoint that really drives the cell •Render the object as a 2-D drawing •Create a simplified cartoon of the drawing with a few elements •Begin removing elements and see when the neuron stops responding
binding problem
a problem with combination coding how do these neurons which represent different features combine their inputs!
face recognition in inferior temporal cortext
pics of faces could not be reduced without causing neuron to stop firing
parvo and magnocellular layers in the lateral geniculate nucleus
Parvocellular pathway carries information primarily from ConesMagnocellular pathway carries information primarily from Rod
bipolar cells
in retina, integrate activity of retinal ganglion and photoreceptors(rods/cones)
