mt 1 deck :) Flashcards
what do neurons do
signal other neurons
what do neurons form
a complex electrical network that spans the brain and projects out to the muscles and sensory organs of the body
structural homogeny
evidence that pour common heritage is still visible in the similar shapes of our bodies and brains
major divisions of the brain
nertebrate nervous system (peripheral and central nervous systems). CNS is comrpised of brain and psinal chord, PNS is semantic and autonomic nervous system
what does semanitc nervous system to
interacts with external environment. afferent nerves that carry sensory signals from skin, skeletal muscles, joints, eyes, ears, etc into the CNS. efferent nerves that carry motor signals from DNS to skeletal muscles.
autonomic nervous system
interacts with internal environment. afferent nerves that carry sensory signals from internal organs to the CNS. efferent nerves that carry signals from CNS to internal organs.
sympathetic nerves
mobilize energy resources in threatening situations via adrenal glands
parasympathetic nerves
conserve energy
corpus callosum
each half of the brain is conected by this tract of neurons
cerebral cortex
part of the telencephalon. Many folds increases surface area. longitudinal fissue is biggest fissure. cerebral commisure connects the cerebral hemispheres, largest commisure is the corpus callosum.
4 lobes of the brain
frontal lobe, parietal lobe, temporal lobe, occipital lobe.
limbic system
hippocampus (memory), amygdala (fear), hypothalamus (pituitary gland)
occipital lobe
vision
temporal lobe
hearing
parietal lobe
bodily sensations (touch, temp, pain)
frontal lobe
movement, planning, motivation
thalamus
above the brain stem. divided into many nuclei for different types of reception.
basal ganglia
group of structures in cerebral hemisphere. caudate nucleus and putamen are striatum. globus pallidus and substantial nigra are made of multiple nuclei. basal ganglia are best know for facilitating movement.
nucleus accumbens
in the basal forebrain (front bottom of brain). outer shell is more limbic, inner core is for motor systems. reward system. part of the mesolimbic pathway. imp for processing situations and moving away from negative situations.
hippocampus
temporal lobe of cerebral hemisphere. known for memory. part of the hippocampal formation.
amygdala
collection of nuclei in temporal lobe. basolateral and cortico-medial division. amygdala is part of limbic system.
primary somatosensory cortex
behind the ventral sulcus. responsible for processing somatic sensations (touch, position of body, pain). info sent to thalamus them primary somatosensory cortex. divided into 3A, 3B, 1 and 2. homonculus.
primary motor cortex
involved with voluntary movement. divided into 2, primary and non primary. primary = homonculus. nonprimary: supplementary and pre motor cortex.
association areas
temporal and parietal lobes as well as prefrontal cortex (planning, voluntary behaviours, inhabition of inappropriate thoughts)
executive function
exerting cognitive effort for long term goals.
sections of pre frontal cortex
dorsolateral, dorsomedial, ventrolateral, ventromedial, and orbitofrontal cortex
oribitofrontal
understand relationship btwn choice and consequence
ventrolateral
inhibiting actions when not appropriate, inhibiting thoughts
dorsolateral
working memory, manipulating things in your mind.
5 methods of manipulating and measuring human brain activity
lesion, transcranial stimulation, EEG, MEG, PET
behaviourists
dont care what happened between the input and the output
cog neuroscis
want to know what happened btwn input and output
lesion studies
using brain damage to learn about cog. can be born with them, can get them via stroke or injury, disease.
transcranial magnetic stimulation & electric brain stimulation
uses electromagnetic coil/lectrode to ramp up or down neuronal activity.
EEG
electrodes on scalp record the electrical activity of the brain. Waves reflect the electrical output of columns of cortical neurons
even related potentials (ERP)
EEG signals compared between groups and conditions.
ERP increased or decreased communication
increased when crests align, decreased when crests dont align
magnetoencephalography (MEG)
magnetic detectors surrounding the head. detects small magnetic fluctuations in brain activity. signal is not distorted by skull so its better for localizing sources of signals than EEG is.
strengths/weakness EEG and MEG
good temporal resolution, EEG is inexpensive, non invasive, direct measure of brain activity. waknesses: poor spatial resolution, all correlational.
intracranial EEG
ECoG. form of intracranial EEG that records activity from grids of electrodes. stereo EEG is when single depth electrodes are inserted.
intracranial EEG pros and cons
great temporal accuracy, great spatial accuracy, useful for synchrony measures, good for looking at high frequencies. weaknesses: invasive, no control over where electrodes are placed, correlational
PET (position emission tomography)
measures radioactive tracers tagging neurotransmitters. expensive and v slow.
change brain, measure behaviour
lesion studies, transcranial stimulation, can infer causality
change behaviour, measure brain
EEG/MEG: electrical activity at the scalp tells tou when but not where.
ECoG/EEG: tells you when and where but its invasive.
ALL: allow measurement of oscillations as mechanistic signals of communication.
PET allows you to measure neurochemical activity
MRI
magnetic resonance imaging. can produce very good spatial resolution anatomical or structural images
fMRI
functional magnetic resonance imaging. measures differences in activity between groups or experimental conditions. does NOT directly measure neuronal activity. BOLD (blood oxygen level dependent)
BOLD
blood oxygen level dependent. dependent variable in fMRI study. statistical maps are produced to show where more oxygenated blood is being used in the brain.
strengths and limits of fMRI
strength: good spatial precision, non invasive.
weakness: expensive, poor temporal precision, indirect measure of brain activity, correlational
fMRI encoding
standard brain mapping. use a stimulus or experimental task and measure activity that is evoked
fMRI decoding
representational. look at brain activity to predice what the stimulus or cog process producing it is
voxel
MRI and fMRI are composed of voxels. fMRI BOLD activation level for every brain voxel.
standard fMRI analyses
encoding. focus on discovering the regions responsible for basic mental processes. identify regions active in a given experimental condition.
encoding fMRI voxel wise analysis
look at every voxel in the brain. ran a stat analysis for every voxel. average BOLD activation for each voxel across trials in each condition. Measure the differences between conditions.
standard fMRI
basic functional map of the brain.
assumption: an area codes for a stimulus if it activates more.
representational fMRI
info is in the pattern of activation across voxels.
decode representations of psychological states from these patters.
multi-voxel pattern analysis (MVPA) for decording representations
how do patterns of activation across voxels represent object categories or mental states. take voxels and use it to train the classifier. it learns what the voxels look like when a particular thing is seen.
representational similarity analysis (RSA) for mapping representational space
RSA is a type of MVPA. looking at how similar brain representations are to each other (are representations for a bird more similar to a chair or another animal).
standard encoding summary
what individual voxels light up more for animate vs inanimate objects?
MVPA summary
based on multi voxel patterns are you looking at a bird or a chair
RSA summary
do multivoxel patterns tell us that our brain represents a robin more like a parrot or a chair?
how is structural connectivity measured
presence of axonal connections
functional connectivity
correlation in activation between BOLD activity in different areas over time. examined while doing an experimental task or lying in the scanner at rest
canonical intrinsic networks
default, control, somato-motor, dorsal attention, visual, salience
where does information from each retina travel
from the nose side crosses to the other side of the brain via optic chiasm, from the outer half of retina stays on same side (ipsilateral).
johannes keppler
discovered that the image on your retina is upside down. this is bc light reflection on your lens causes the image to be flipped.
primary visual cortex (V1) maps:
where the visual info enters the cortex, retinotopicall organized, neurons have small receptive fields, V1 cells respond to specific types of info that allow us to detect contrast, edges, and motion direction
retinotopic map
each neuron sees only one point (one pixel in an image).
V2-V4 & MT
V2-V4 are regions that are part of occipital cortex. in these regions you find neurons that are responsive to other aspects of the visual world (shape, colour, motion, spatial location).
feedforward processing
info travels from occipital cortex to parietal and temporal. early stages processes elements, later stages integrates them
parallel visual pathways
dorsal and ventral. branch from primary to temoral and parietal
activity in dorsal visual stream
allows you to use the shape and orientation of an object to guide the motion of your hand when reaching for it.. the where and how stream. planned object-directed action
activity in ventral stream
the what stream. LOC uses shape and other info to identify the object.
apperceptive agnosia
where perception is disrupted. cant recognize a chair from below, cant recognize the forest for the trees.
associative agnosia
where semantic meaning is disrupted. cant recognize a bear when it is in front of you, cant recognize trees in a forest.
bottom up vision
moves from stages of earlier to later, and from simple and concrete at the bottom to more complex and abstract at the top.
feature detection model
we detect the features of an object and then glue them together into a whole. V1 passes through the ventral stream and pieces are put together at varying degrees of abstract. at the end it matches the mental template.
LOC
key role in detecting whole objects
hemodynamic response function
describes the change over time of the ratio of oxygenated to deoxygenated blood after an event. measuring the plateau is the block design.
grill-spector study
to see what lies between the ventral stream for whole objects and just bits of it, they tested the brain with scrambled pics.. higher plateau means voxels in the region of interest were more responsive to the image.
V1- lots of activity for the scramble
V4v- lots of activity for the intermediate level of scrambling
LOC - lots of activity for whole images and small bits, not for intermediate.
concluded that regions along the ventral stream progress from processing bits, to part, to whole images.
object recognition; intreim study
retinotopic cells in V1 have small receptive fields that perceive small bits of info.
challenges to object recognition
higher order neurons collect info from lower order neurons to make a decision about a view independent representation (same thing no matter distance/angle).
size invariance
the ability to know the object is the same when it is a different size on the retina
viewpoint invariance
the ability to recognize objects from different viewpoints
adaptive supression
when you see the same image repated, the hemodynamic response is smaller than when you are seeing a new image
anterior LOC (viewpoint or size invaraince)
both
early visual cortex and posterior LOC (size/viewpoint invariant)
not size or viewpoint invariant
thatcher effect (inversion effect)
if a face is upsidedown, we cannot tell the emotion nearly as well. we process an entire face at one time (not in its individual pieces).
prosopagnosia
you can recognize objects but not faces (damage to right side temporal lobe)
regions sensitive to faces
temporal lobe, amygdala
electrical stimulation to FFA
the face that the person is looking at will change to look like the face of another, unknown, person.
in what order are faces decoded
age -> gender -> identity
what do the amygdala and FFA have in common
the FFA recognizes faces, and the amygdala helps the FFA recognize what emotion the face is showing us.
Hadara paper
wanted to see what the influence of culture was on amygdala responses to negative emotional expressions of racial ingroup and outgroup faces. participants in fMRI scanner, shown images of 2 people, and had to match 1 of the 2 to the preset image. they were looking to see if the particpant’s amygdala would light up more for in group or out group images. native Japanese participants showed greater amygdala activation for angry or fearful faces of their own race.
