Cog neuro exam 1 Flashcards
ch 1, 2, 3, 5
What is the localizationist view?
specific cognitive functions have a specific location in the brain
What is the aggregate view?
cognitive processes are distributed throughout the brain.
What is phrenology?
the pseduoscientific view that there were 35 areas that would differ in size on the skull and could predict personality (anatomical phrenology)
What supported the localization view?
Phineas Gage (frontal lobe), broca’s area, wernicke’s area, HM: Hippocampus, damage causing face blindness, Brodmann (cytoarchitectonics)
Cognitition
the process of knowing
Neuroscience
the study of the nervous system
Cognitive neuroscience
the study of how the brain enables the mind
What is dualism?
Mind and body as separate, Descartes, Mind (pineal gland) is immortal and the body is mortal
Empiricism
All knowledge comes from sensory experiences, the mind is a blank slate, Hobbes, Locke, Hume, Mull
Localization (mass action) vs equipotentiality (anti-localization)
Localization: specific processes are localized within circumscribed brain regions (destroyed parts of pigeon and rat brains and saw localization)
Aggregate Field View: cognitive processes are controlled by the entire brain, removed localized portions of cortex and noted their effects on bird behaviors (Jean Pierre Florens)
What is cyctoarchitectonics?
the study of the cellular composition of structures in the body. Brodmann used tissue stains to visualize the different cells in different areas and identified 52 distinct regions- consistent with localizationist view.
Neuron Doctrine
the nervous system is made up of individual cells. The basic functional unit of the brain is the single nerve cell, the neuron.
How did the neuron doctrine arise?
Golgi believed the whole brain was a syncytium, but Cajal found that neurons were discrete entities (unitary). Cajal used Golgi staining and saw they were connected together
What is the neuron doctrines competing theory?
Reticular theory (everything is continuous)
What did Fritz and Hitzig do?
o Electrical stimulation in a dog to produce movement
o Observed that the stimulation produced characteristic movements in the dog which led to neuroanatomists to analyze the cerebral cortex and its cellular organization more closely
oDiscovered the motor cortex
Rostral
Front of the brain, closest to the eyes
Dorsal
(think dorsal fin)
Top of the brain, closest to the hair
Caudal
back of the brain, closest to the cerebellum
What are ventricles for?
Ventricles contain cerebrospinal fluid, allows the brain to float, helps regulate pressure, shock absorption, and damage to the ventricle system is dangerous
Ventral
bottom of the brain, closest to the ear
Why is the cortex folded?
its a larger surface area in a smaller space so it can bring neurons closer to reduce axonal distance and connection times.
Sulci lobes
Lobes of the cortex: infoldings of the cortical sheet (crevices)
Gyri
crowns of the folded tissue that are visible on the surface
central sulcus
divides the frontal lobe from the parietal lobe
Sylvian (lateral) fissure
separates the temporal lobe from the frontal and parietal lobes
What distinguishes the occipital lobe from the parietal and temporal lobes?
the parieto-occipital notch
Where is the insula located?
Between the temporal and frontal lobes
Where are the four functional areas located?
Frontal lobe: front
Occipital lobe: back
Parietal lobe: top
Temporal lobe: bottom
functions of the frontal lobe
Motor cortex, complex cognitive processes, imagination, decision making, cognitive control, reasoning, problem solving
occipital lobe functions
contains primary visual cortex at back of the head, vision
Parietal lobe functions
primary somatosensory cortex, perception of spatial movement, touch
Temporal lobe functions
primary auditory cortex, wernicke’s area, face and object recognition, hearing
Cell body (soma)
contains the nucleus and other parts of the cell needed to sustain life
Dendrites
branching extensions of the neuron that receive inputs from other neurons (take information in)
axon
single process that extends from the cellbody and sends information out of the neuron or down the length of the axon
Axon terminal
Found at the end of the axon where synapses and other neurons are found, neurotransmitters are stored
Myelin Sheath
Layers of a fatty substance as insulation for axon, allows action potential to move quickly
Receptor site/receptor
can be specialized to certain molecules/neurotransmitters on the postsynaptic neuron, protein membrane site where neurotransmitters may bind
Synapse
the space between the terminal buttons of one axon and the dendrites of the next one so chemical or electric signals are passed from one cell to the next
Nodes of Ranvier
Gaps between myelin sheath, allow for saltatory conduction ( rapid electrical ion diffusion)
Schwann cells
glial cell, create myelin in peripheral nervous system, found close to axons and peripheral nerves
Neurotransmitter
signaling molecule, Chemical signal released by pre-synaptic neuron and picked up by post-synaptic neuron
Action potential
Rapid depolarization and repolarization of a small region of the membrane caused by the opening and closing of ion channels
o Glial cells
provide structural support and electrical insulation to neurons and modulating neuronal activity
Form myelin sheath
Transmits ions, keeps out bacteria and large hydrophilic molecules
Lets in oxygen, CO2, hormones, and respond to and release neurotransmitters
Oligodendrocytes
creates myelin in the CNS
Astrocytes
large glial cells with round or radially symmetrical forms, creates a blood brain barrier between the tissues of the CNS and blood
Microglial Cells
small and irregularly shaped; phagocytes that devour and remove damaged cells.Microglia cells are the immune cells of the central nervous system and consequently play important roles in brain infections and inflammation.
Which ions are involved in the neuron’s electrical potential
K+, Na+, CI-, Proteins (A)
Inner: K+, A
Outer: Na+, CI-
What are the steps in the neuronal signaling pathway?
receive–evaluate–transmit information
1. Graded potential reaches the axon and depolarizes above a threshold which causes electrical discharge
2. Neuron fires (all or nothing law)
3. Change originates near the cell body. Positive charged particles flow into the axon and then flow out rapidly
4. a spike in positive charge followed by a sudden decrease in charge shoots down the axon terminal
Transverse (axial)
separates top from bottom
Coronal
separates front from back
Saggital slice
Seperates left from right
Lateral view
side
Medial view
Middle
Dorsal
top
ventral
below
Dura matter
outer membrane and below the skull, most protective, encases the brain and spinal cord
Arachnoid mater
the middle layer of your meninges, lies directly below your dura mater. It’s a thin layer that lays between your dura mater and pia mater. It doesn’t contain blood vessels or nerves.
Pia matter
inner membrane and most delicate. Allows blood vessels to permeate.
Gyrus
o Gyrus: rounded surface on the cerebral cortex that one can see upon gross anatomical viewing (raised tissue layer, convoluted ridges)
FOLDS OR BUMPS
Folding the cerebral cortex creates gyri and sulci
Sulcus
a fissure that appears as a cut or a crease at the surface of the cerebral cortex (groove between structures)
INDENTATIONS OR GROOVES
Central Sulcus
a deep fold or tissue that divides the frontal lobe from the parietal lobe (primary motor cortex to primary somatosensory cortex)
Gray Matter
regions of the nervous system that contain primarily neuronal cell bodies. Gray matter includes the cerebral cortex, the basal ganglia, and the nuclei of the thalamus. Gray matter is so called because in preservative solution, these structures look gray in comparison to the white matter
Composed of neuronal cell bodies and glia
Made up of cell bodies (soma of neurons) and located around the outer surface.
White Matter
regions of the nervous system composed of millions of individual axons, each surrounded by myelin. Myelin is what gives the fibers their whitish color.
Composed of axons and glial cells
* Covered in myelin sheath which is made up of glial cells
Arteries
carries oxygenated blood away from the heart and toward the brain and organs; supplies the brain with blood
Vertebral Arteries
supply blood to the caudal portion of brain
internal carotid arteries
supply blood to wider brain regions
Why is redundancy important with arteries?
o Redundance means that any particular area of the brain is usually supplied by more than one piece of the arterial system
Meaning that you could block capillaries that supply one area, but there are other capillaries that also supply that area. This can allow us to have that blockage but not experience a stroke.
What happens if an artery is blocked?
o As a safety measure for blockage, the circulatory system can reroute blood to reduce the probability of a disruption in blood supply
If the blood flow is blocked, cortical areas supplied by that artery could be damaged and that can impair cognitive functions
what is the limbic lobe made up of?
the cingulate gyrus (a band of cerebral cortex that extends above the corpus callosum in the anterior-posterior direction and spans both the frontal and parietal lobes)
Cingulate gyrus, hypothalamus, anterior thalamic nuclei, hippocampus (ALL apart of limbic system)
Where are all areas of the limbic system located?
ventromedial temporal lobe (on top of the brainstem and under the cerebral cortex
What is included in the limbic system?
amygdala, hippocampus, orbitofrontal cortex, parts of the basal ganglia, and sometimes the medial dorsal nucleus of the thalamus
Limbic system functions
Binding scattered information
Concerning recent events and experiences (supports memory)
Focusing emotion and motivational states
Thirst, hunger, libido
Perceiving taste, smell, pain
Linking autonomic, hormonal, and immunological states with mental activity
Cerebellum function and location and characteristics
o Clings to the brainstem at the level of the pons
o Home to most of the brains neurons
o Surface is covered with thinly spaced, parallel grooves but is just a continuous layer of tightly folded neural tissue
o Forms the roof of the fourth ventricle and sits on the cerebellar peduncles
o Subdivisions include the cerebellar cortex, four pairs of deep nuclei, internal white matter
o Resembles the forebrain’s cerebral
o Critical for maintaining posture, walking, and performing coordinated movements
o Integrates information about the body such as its size and speed with motor commands
If damaged, your movements are uncoordinated and you can’t maintain balance
Spatial vs Temporal resolution
o Spatial: the capacity a technique has to tell you exactly which area of the brain is active
o Temporal: describes its ability to tell you exactly when the activation happened
What is cognitive psychology?
o Study of behavior to figure out mental representations
o Emphasis on mathematics and calculations
There is this assumption saying we do not directly perceive and act in the world; perceptions, thoughts, and actions depend on internal transformation/computations
o Goals:
Describe human performance
Identify internal processing that underlies performance
o Concepts
Information processing depends on mental representations
Mental reps undergo transformation
o Encode, compare, decide, respond (input-rep-transformation-output)
Physical identity, phonetic identity, category
Comparisons happen in serial not in parallel (Sternberg memory)
What is the purpose of mathematical psychology and computer modeling? Pros/cons?
o Computers represent and transform info
Good model for studying human cognition
AI, symbols, mapping
Simplification, not neurons, nonlinear activations, small in scale and narrow problems
What are some pros/cons of neuropsychology?
o Pros: can be a powerful test of brain region function; testable predications for other techniques, examination of temporal effects of disorders
o Cons: can’t control diffuse versus focal; no proper controls; can’t control location, size, extent; small sample sizes
What are some pros/cons of single cell recordings?
o Microelectrode inserted into neuron and action potentials are recorded
o Multiunit recording= an array of electrodes is inserted in brain such that many cells can be recorded simultaneously
Raster plots show timing of AP
o Recordings can be done to identify surgical sites in human medial temporal lobe for epilepsy
o Pros: excellent spatial AND temporal resolution (“gold standard”)
o Cons: poor spatial coverage, is single neurons representative of whole region? not healthy in humans, not casual
Intracellular vs. Extracellular recording
o Extracellular: more common, action potentials, no way to know if it accurately represents the change in electrical activity
o Intracellular: difficult, graded membrane potentials, usually damages cell
Basic idea of CT and how it works
o A noninvasive neuro imaging method that provides images of internal structures such as the brain
o X-ray absorption correlates with tissue density
Bone absorbs a lot of radiation and appears white
o Air and CSF absorb very little radiation
o Neural tissue absorbs moderate amount of radiation
o Several x-rays are taken from difference angles
o X-rays are combined using 3D scanning software methods
Reconstruction of 3D space from the compressed 2D images
Basic idea of MRI and fMRI and how they work
o MRI
Neuroimaging technique that exploits the magnetic properties of organic tissue
Certain atoms are especially sensitized to magnetic forces because of the number of protons and neutrons in their nuclei
Orientation of the atoms can be altered by the presence of a strong magnetic field
Magnetic fields aligns orientation of protons, when turned off, protons release energy and spin back to orientation
o FMRI
Neuroimaging method that utilizes MRI to track blood flow changes in the brain that are thought to be correlated with local changes in neuro activity
Altered blood flow alters the RF signal from active brain regions
As blood flow increases, so does the oxygen concentration in the blood
MRI measures how long it takes protons to return to aligned spin
Excellent spatial resolution
Poor temporal resolution
FMRI data are noisy and BOLD response is SLUGGISH
o DTI
Uses an MRI scanner that allows white matter pathways to be imaged
* Water diffusion
Basic idea of EEG and ERP vs. MEG
o EEG (electroencephalography)
A technique to measure the electrical activity of the brain
* Changes in voltages between electrodes
Surface recordings are made from electrodes placed on the scalp
ER time-lock data to event to look at magnitude/latency of response
Pro: temporal resolution
Con: spatial localization
The EEG signal includes endogenous changes in electrical activity due to changes in arousal and changes triggered by events
Measures changes in voltages between electrodes and relies on dipoles created a cortical dendrites
o MEG (magnetoencephalography)
Measures the magnetic fields produced by the brain’s electrical activity and is measured by cortical response
Measures electrical activity that is parallel to the surface of the skull (small magnetic fields that can be measured by sensitive magnetic detectors placed along the scalp)
Spatial resolution is superior because magnetic signals are minimally distorted by organic tissue such as the brain or skull
Same temporal resolution as ERP
More accurate is spatial localization and more accurate solution to the inverse problem
SQUIDS- device used to record MEG
o ERP (even-related potential)
A change in electrical activity that is time-locked to specific events, such as the presentation of a stimulus embedded within an EEG recording
When the events are repeated many times, averaging the EEG signals reveals the relatively small changes in neural activity triggered by these events
Extracting the response evoked by an external event
Coup vs. Countercoup
o Orbital region injuries
o Other areas susceptible as well (occipital and temporal lobes)
Coup front, countercoup back
o Coup: initial impact
o Counter-coup: secondary impact
What are the basic steps in producing the BOLD signal? (Blood Oxygen Level-Dependent)
o Change in the magnetic resonance (MR) signal intensity of the hydrogen ion concentration in the brain, which results from changes in the local tissue oxygenated state
o Increased neural activity triggers an increase in the amount of oxygenated blood entering local capillaries in the tissue, thus altering the ratio of oxygenated to deoxygenated hemoglobin in the tissue
o An indirect measure of neural activity and is delayed with respect to the neural activity that leads to the signal
What are the two main types of fMRI designs?
o Block design
The researcher integrates the recorded neural activity over a “block” of time during which the participant performs multiple trials of the same type
During some blocks of 40 seconds, the participant might view static dots whereas in other 40 second blocks, the dots are moving about in a random fashion
Compares neural activations between experimental and control scanning phases
Continuous block of the same condition and take the average across the interval
o Event-related Design
Different types of trials may occur randomly
BOLD response can be extracted from signal data
BOLD response links to specific events such as the presentation of a stimulus or the onset of a movement
Improves the experimental design because the researcher presents the experimental and control trials randomly
Single trials with many repetitions (take average from trials
Basic idea behind TMS and value in research
o Noninvasive method used to stimulate neurons in the intact human brain
o A strong electrical current is rapidly generated in a coil placed over the targeted region which generates a magnetic field that causes the neurons in the underlying region to discharge
o Used to evaluate motor function by direct stimulation of the motor cortex
o Procedure is used to disrupt neural processing creating reversible lesions
o Area of neural activation depends on the shape and position of TMS coil
o Has become valuable in research because of its ability to induce “virtual lesions”
The experimenter is disrupting normal activity in a selected region of the cortex
Safe and noninvasive to allow comparisons between stimulated and non stimulated conditions
o Allows for double dissociations
o Coil is positioned over occipital lobe to disrupt visual processing, participant attempts to name letters on screen, TMS pulse is applied before, during, or after stimulus presentation, if TMS pulse occurs around 100ms after letter presentation, perception is disrupted, performance also goes down if pulse comes around 50ms before the stimulus
Understand single dissociations and double dissociations in neuroscience research
o Single Dissociation: a method used to develop functional models of mental and/or neural processes
Requires a minimum of two groups AND two tasks
Single dissociation is present when the groups differ in their performance on one task but not the other
Provide weak evidence of functional specialization since it is possible that the two tasks differ in terms of their sensitivity to detect group differences
Example: Broca’s area in the left hemisphere impairs a person’s ability to speak fluently, but it does not impair comprehension
Damage to brain structure X disrupts one function but not the other
* Patient A’s brain is damaged in area X thus, face recognition is impaired but object recognition is normal
CANNOT be independent
To draw a conclusion about area X, we would want to know that damage to some other area of the brain results in opposite symptoms
o Double Dissociation: a method used to develop functional models of mental and/or neural processes
Requires a minimum of two groups AND two tasks
Double dissociation is present when one group is impaired on one task and the other group is impaired on the other task
Present when one experimental manipulation produces changes in activation in one neural region and a different manipulation produces changes in activation in a different neural region
Provide strong arguments that the observed differences in performance reflect functional differences between the groups
Damage to area X impairs the ability to do task A but not task B and damage it area Y impairs the ability to do task B but not task A
* Damage to one part of the brain causes function A to be absent while function B is present and damage to another area causes function B to be absent while function A is present
* Patient A: brain is damaged in area X thus face recognition is impaired but object recognition is normal
* Patient B: brain is damaged in area Y thus face recognition is normal but object recognition is impaired
o Able to see that area X is involved with face recognition
Example: damage to Wernicke’s area impairs comprehension but not the ability to speak fluently (ADDED to the Broca’s area example)
Identifies whether two cognitive functions are independent of each other
* Researchers can compare performances of the two groups to each other
Know the basics of visual processing.
- Eye (remote sensation)
- Lens inverts and focuses
- Retina (photoreceptors rods and cons)
- Light causes changes in photopigments
- Electrical current—neural signal
- Bipolar and ganglion cells (horizontal connections)
- Retinal ganglion cells fire action potentials
- Optic nerve
- Optic chiasm (contralateral crossover: LVF to R-hem)
- Thalamus (LGN)
- Optic radiation
- Primary visual cortex (V1)
- Secondary visual areas (V2,V3)
i. eye> lens inverts and focuses> retina (photoreceptors)> light causes changes in pigments> electrical current> bipolar and ganglion cells> retinal ganglion cells fire AP> optic nerve> optic chiasm (contralateral crossover LVF to Rhem)> thalamus> optic radiation> primary visual cortex V1> secondary visual areas
ii. Primary cortex: V1, “striate cortex”
iii. Secondary visual cortex: V2/3, “extrastriate”
What is retinotopic mapping
fMRI retinotopic mapping provides detailed information about the correspondence between the visual field and its cortical representation in the individual subject. Localizes functional image data w/ the functional architecture of visual system.
What are receptive fields in visual processing?
o V1: single cell is monitored; monkey maintains fixation; stimuli presented at various locations in visual field
Electrophysiological response in visual cortex: this cell responds to stimuli in upper right quadrant and indicates receptive field of a neuron
o Receptive field: the area of external space within which a stimulus must be presented to activate the cell
Have a center-surround organization (sharpen contrast and edge detection
How does the ear receive sounds waves and transmit them to the brain? (basics)
o Auditory pathway
Outer ear—middle ear—inner ear—cochlea—auditory nerve—midbrain—thalamus MGN—primary auditory cortex A1—A2
* Auditory nerve
* Midbrain relays (cochlear nucleus, inferior colliculus)
* Thalamus (MGN)
* Primary auditory cortex (A1)
* Secondary auditory cortex (A2)
What is a tonotopic vs. retinotopic map? à What arrangement for sensory processing is typically accepted for vision?
a. Tonotopic: the spatial arrangement of where sounds of different frequency are processed in the brain
i. Cochlea organized by frequency (tonotopic map): hair cells at base activated by high frequencies; at apex, low frequencies
o Auditory and begins at cochlea
o Retinotopic: mapping of visual input from the retina to neurons, particularly those neurons within the visual stream (ACCEPTED FOR VISION)
o Retinotopic organization of V1 and the contralateral projections of the visual hemifields into the hemispheres of the brain respectively
What are the primary functions of the following areas: LGN, V1, V4, and V5?
- V1: oriented lines, primary visual cortex/striate cortex, sharpen contrast, edge detection
- LGN: vision relay system in thalamus; the thalamus, output directed to primary visual cortex
- V4: color, shapes, attention
- V5: motion, human area MT
- MT V5: movement, speed
- Higher level vision pathways
o Dorsal: where
o Ventral: what
Which sense does not go directly through the thalamus?
o olfaction/smell
What is the location of the primary auditory cortex?
o Lies in the superior temporal gyrus of the temporal lobe and extends into the lateral sulcus and the transvers
o A1—Heschl’s Gyrus
i. Located within the Sylvian fissure on the surface of the supra temporal plane and upper banks of the superior temporal gyrus (contains tonotopic map)
Know the sensory role of lateral geniculate nucleus (LGN)
o Portion of the thalamus that processes visual information
Know the sensory role of medial geniculate nucleus (MGN)
o Portion of the thalamus that processes visual information
Know the sensory role of the Ventral Posterior Nuclear Complex
o Thalamus: somatosensory information
What is the role of interaural timing & interaural intensity?
o Interaural timing difference: sound reaches ear closest first
o Interaural intensity difference: sound louder in closest ear
o The neurons compare firing rates from both ears
- How are somatosensory messages translated and sent to the brain? (basics)
o Somatosensory goes through the thalamus
o VENTRAL POSTERIOR NUCLEAR COMPLEX NUCLEUS
Taste does too!
o Pathway: dorsal root ganglion, spinal cord, brainstem and midbrain (cross)
o Receptors in the skin are called corpuscles
o Receptors send signals to the brainstem via spinal cord then cross over to the contralateral side of the thalamus
1. Spinal nerve (dorsal root ganglion)
2. Spinal cord
3. Brainstem/midbrain relays (cross)
4. Thalamus (ventral posterior nuclear complex)
5. Primary somatosensory cortex (S1)
6. Secondary somatosensory cortex (S2)
7. Cerebellum
2. Touch receptors detect stimulation of the skin and generate action potentials
3. The axons of the receptors enter the dorsal horn of the spinal cord and synapse on spinal neurons, some of which ascend along the dorsal column
4. The first synapse of the ascending column is made in the medulla
5. Output from the medulla crosses to innervate the contralateral thalamus, and from there projects to the somatosensory cortex
Know about cortical plasticity.
o Size and shape of cortical sensory and motor maps can be altered by experience
o Severing a finger causes cortex signaling to cover adjacent finger
o Remapping occurs when digits are sewed together
o The brain has an amazing ability to “rewire” cortical areas for adaptation
What is synesthesia?
o Mixing of two (or more) senses
o Colored letters
o Colored songs or sounds
o Remember the Stroop task (green word that is red)
Know about phantom limbs, and what the most effective treatment is.
o Phantom limbs is when an individual feels pain as if their other limb that was amputated is still there
o Best treatment is mirror treatment (“mirror neurons”)
o Sometimes amputated limbs still take up cortical space and “misfire”
Know the basics behind gustatory transmission of tastes to our brain.
o The tongue contains small bumps called papillae, within or near which taste buds are situated.
o In the tongues taste buds, the taste receptors receive sensory input via two important mechanisms- depolarization and neurotransmitter release
o Intake of salty foods leads more sodium ions to enter the receptor, causing the said mechanisms
o Transmission: mouth—tastant binds to taste cell—chemical transduction—action potential—gustatory nerves
o Pathway: gustatory nerves—midbrain relays—thalamus—primary gustatory complex—orbitofrontal cortex
Know the basics behind olfactory transmission of smells to the brain.
o Smell doesn’t go through the thalamus
1. Nose
2. Nasal cavity (odor receptors)
3. Odorant binds to bipolar neuron (combinatorial coding)
4. Signaling cascade—action potential
5. Signal sent to olfactory bulb (glomeruli)
6. Olfactory nerve
o Olfactory nerve, primary olfactory cortex, orbitofrontal cortex (secondary olfactory)
What are some problems in studying olfactory sensation (in fMRI)?
- Controlling how much odorant to deliver
- The device itself
- Controlling how long the odorant will persist
Which sense does not predominantly project contralaterally
o Taste (gustation)
What are the types of sensory receptors in the skin?
o Merkel’s: for regular touch
o Meissner’s: for light touch
o Pacinian: for deep pressure
o Ruffini Corpuscles: for temperature information
o Nociceptors: signal pain via both myelinated and unmyelinated fibers
o Proprioceptors: at linkages of muscles and tendons provide physical state
How many types of receptors in the olfactory epithelium?
o More than 1000 types of receptors: different odorants bind to different combinations of receptors
S1: contains a representation of the body called the homunculus
S2: builds more complex representations, such as object texture and size
- Receives information from both hemispheres, forming integrated representations (like holding something in both hands)
