Cog Neuro II Bullet Points

Pasko Rakic

•Develloped the concept that Brain organization determined in the ventricular zone

•He states that a ventricular “protomap” determines functional variation and predicts laminar organization of the brain

• From this cortical - cortical connection forms, with radiations determining laminar organization

Jean Piaget

• A stage theory of cognitive development • General theoretical framework: “genetic epistemology” • A theory of how knowledge develops in humans • Genetic Epistemology: • A central concept: “cognitive structures” • Patterns of physical or mental action that underlie specific acts of intelligence • Correspond to stages of child development

Rene Baillergeon

• Tested Piaget’s theory about object permanence • Has found that 3.5 month olds are surprised or puzzled by the behavior of the car • Concludes that infants have more information about object permanence that piaget thought • Babies as young as 3.5 months express surprise when the sequence of events suggest that the object has disappeared • Suggests that children exhibit “object permanence” much younger than what Piaget thought they did

Judy DeLoache

• Judy DeLoache: children’s ability to use symbols (mental representations of objects in the world) • Uses a scale model as a symbol of a real room • She finds that 2.5 year olds have difficulty with her task (find the big snoopy in the real room after seeing the little snoopy being hidden in model room) • But 3 y.o. Have no difficulties with the task

Gretchen Van de Walle

• Piaget argued that quantitative skills did not develop until around age 7 • More recent research however has shown that infants can distinguish differences in numbers of objects much younger • Gretchen Van de Walle studies quantitative ability in children • Showed 2 y.o. 2 trays • Tray with 2 vs 1 object was the “winning tray” (there was a prize in it) • Van de Walle than showed toddlers tray with 3 vs 4 items • Subjects reliably picked the tray with the greater number as the “winning tray”

Adele Diamond

• Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Behavior suggests “preservation” of responding • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

Alexander Luria

• Posterior visuospatial dominance • Done on soldiers • Pt.’s with parietal injuries had normal visual acuity but were unable to scan visually or reach for an object. Could not give a coherent scene description. • Holmes and Luria studied head-wounded soldiers • Posterior parietal cortex associated with personal space perception and scene coherence

Phineas Gage

• Involuntary resection of prefrontal cortex • Revealed important role of PFC in personality and numerous higher-order “executive” functions • Change in personality and higher-order “executive” functioning

Patient HM

• Bilateral temporal lobe resection for treatment of epilepsy • Included removal of hippocampus and amygdala from both sides • Resulted in retrograde amnesia for the previous 10 years • Profound anterograde amnesia • Short-term or working memory normal • Taught us about the difference between declarative and nondeclarative memories • Declarative memories: involve the conscious recollection of events and information • H.M. Lost ability • Non declarative: (skilled memory) involves the ability to acquire and perform new behaviors H.M. • Tower of Hanoi

The methods of experimental psychology

• Behavior is the basic unit of study • Phenomena must be well characterized • Stimulus -> cognition -> response • Basic units of measurement: • Reaction time • Accuracy • Much work has been done to establish the validity and reliability of these measurements • Basic methods have yielded a circumscribed number of phenomena in need of explanation

Posner letter-matching task

• “Are the 2 letters from the same vowel-consonant category or not?” • Results demonstrate that multiple representations are activated by a single stimulus • Reaction time decreases as time between letter presentations increases

The Sternberg item-recognition Task

• Reaction time increases monotonically with increasing memory set-size • Similar reaction time slopes for both “yes” and “no” responses • Shows string of letters and then single letter pops on screen and must say if it was part of string of letters or not • Delayed response task • Short Term Memory • Only ever responding to a single letter • “Serial exhaustive search” (Sternberg saw evidence of this) • Absence in yes / no response function they must sort through every item • Sequentially searching in memory for letters • Memory retrieval is a serial comparison process between items in memory and those in the world • Each comparison takes a fixed amount of time (msec) • Mental operations can be quantified in terms of the amount of time they take

Stroop task

• Subjects take longer to name a color word (red) when it is printed in a color that does not match the word • Multiple representations • “Privleged access” of some representations over others

Word-superiority effect

• A target letter can be identified more quickly when it is imbedded in a word than when it appears among a random letter string • Can ID letter in word > than in random string of letters • In terms of speed and accuracy

Properties of the reaction-time distribution

• R foot curve (positive skewed distribution of reaction times) • L foot curve (longer reaction time with accuracy) • Can use reaction time and accuracy to determine cognitive processes (Speed/accuracy trade-off) • Manipulation are response bias (put more emphasis on speed therefore graph is skewed)

Speed-accuracy trade-off

• L foot curve (longer reaction time with accuracy) • Can use reaction time and accuracy to determine cognitive processes (Speed/accuracy trade-off) • Manipulation are response bias (put more emphasis on speed therefore graph is skewed)

Single and Double dissociations

• Single dissociation: • 1 patient group, 1 control group • 2 tasks • Difference between groups only occurs in Task A • Inference Problems with Single Dissociations: • Both tasks assumed to be equally sensitive to group differences • Single dissociation may result from general effects of trauma, not specific effect of lesion • Double dissociation: • [ NOT COVERED IN THE SLIDES ]

Lesion methods

• The study of cognitive deficits following brain damage

The role of a missing brain region may be inferred from what the patient cannot do after it is removed •

The Lesion Method: (does not accommodate neuroplasticity

• Laid the empirical foundation for modern cognitive neuroscience

Logic is based on a localizationist perspective

• An “additive factors” logic

• Does not take into account the adaptive “parallel” nature of brain function

• Electrically Produced Lesion:

• DC Lesions

• RF Lesions

• Poison-produced lesions: Destroys chemical systems by neurotoxins

• Leaves other systems intact •

Encephalotome : Insulated wire inserted into brain tissue using stereotaxic device • Tissue destroyed • Axons severed •

Naturally Occurring Lesions: • Tumors • Degenerative disorders • Infection • Head trauma • Epilepsy

Single unit recording

• Extracellular: • Strongest signal obtained from closest cell • Filters used to wipe out weaker signal • Requires repetition to determine if signal is typical • Single unit recording intracellular: • Actual penetration of cell by micropipette • Requires fine control • Tolerance within a single micron • Blood pulse can change location • Can be used to determine the response characteristics of single cells • For instance Hubel and Wiesel used this method to map the response characteristics of primary visual cortex • Single cell recording permits observation of spike trains that correlate with stimulus presentation • Mapping of foveal-extrafoveal mappings in V1 • Mapping of ocular-dominance and orientation columns in V1 • … and functional mapping of specific brain regions (tonotopic mapping of primary auditory cortex)

Microiontophoresis

• Simultaneous recording while depositing chemicals on neuron • Uses multibarreled micropipette • Complicated method • Difficult to know what to manipulate: • Cognitive tasks? • Chemicals?

Degenerative disorders

• Alzheimer’s Disease: • Cause unknown • Progression runs posterior to anterior • Characterized by presence of cortical “amyloid plaques” • Memory loss early; executive, personality late • Pick’s disease • Cause unknown • Progression runs anterior to posterior (inverse of Alzheimer's) • Characterized by presence of cortical “pick’s bodies” (bundles of disorganized filaments) • Filaments composed of proteins • Huntington’s Disease: • Caudate and putamen of basal ganglia degenerate • GABA levels reduced in basal ganglia • Ach also reduced • Parkinson’s Disease: • Lack of dopamine • Results from atrophy of substantia nigra • Substantia nigra responsible for production of dopamine

The multi-barreled micropipette

• Simultaneous recording while depositing chemicals on neuron • Uses multibarreled micropipette

The methodology of Positron Emission Tomography

• Production of positron emitting isotope in a cyclotron • Chemistry of labeling compound with positron emitter and preparing compound in a form suitable for administration in humans • Transport of labeled compound from chemistry lab to PET lab • Administration (injection) of tracer compoun & data acquisition with PET camera • Processing of data from PET camera to extract information related to the tracer’s kinetics in the body • Interpretation of result • Positrons: • When a positron meets an electron the collision creates 2 gamma rays that have the same energy but go in opposite directions, • PET detects the gamma rays as they leave the pt’s body. • The information is fed to a computer and makes a picture • Depending on the type of tracer, different gamma rays are given off and detected. In this way multiple things can be evaluated • [18F]-labeled 2-deoxyglucose (FDG) is used to study glucose metabolism • [15O]-labeled water measures oxygen extraction. [15O]-labeled oxygen • [13N]-labeled ammonia can be used to measure blood flow • [11C]-labeled methionine and leucine can be used to evaluate amino acid uptake and protein synthesis • Many detectors are connected to a photomultiplier tube and arranged in circular, hexagonal, or orthogonal rings • The field of view is defined by the width of the array of detectors • The smaller the size of the detectors the better the spatial resolution of the PET system

The methodology of functional magnetic resonance imaging

• The strong magnetic field causes hydrogen nuclei to align in a common orientation • Short radio pulses from the head coil briefly realign these nuclei and then they return to their original alignment • Different kinds of tissue return at different rates, sending different radio frequencies back to the antenna • By detecting what frequencies come from different areas, we can determine that location of different tissue types and construct 3D brain images • Takes advantage of the fact that neural activity is followed by blood flow in a highly predictable manner • Altered blood flow alters RF signal from active brain regions • Neurons in the brain need oxygen from blood to do their work. When they’re working harder, they need more oxygen • fMRI can detect changes in the relative levels of oxygen in different areas of the brain • If certain areas show relatively higher levels of oxygen during certain types of tasks, we can hypothesize that these areas have something to do with that kind of thinking. We say that kind of task activates that area. • The time course of a voxel shown as percentage of mean intensity • Analysis software compares the model to each voxel and determine whether the fit is statistically significant

The methodology of functional electroencepholography

• Population recording • Temporally high-density recording • Critically depends upon trial-averaging • High temporal resolution • Maps based on known temporal, physical, and physiological properties of the head and brain • Event-related field maps • In combination with dipole technology can produce more precise localization • Tell inferences of consciousness (alpha v beta) (asleep v awake) (varying levels of consciousness)

Temporal and spatial resolution in imaging methods

• EEG: good for high temporal resolution (low spatial resolution) • PET: middle (reasonably good spatial resolution) (not the best temporal resolution because time crunch due to radioactive substance) • Measures glucose uptake to index neural activity • Poor spatial resolution • Often accompanied by MRI for more accurate localization • Generates high resolution structural images • Generates high resolution functional images • fMRI: temporal resolution not the best

Embryonic development

• Fertilization • Multicellular blastula develops (WILL BE ON EXAM) • Contains precursors of three main types of cell lines • Ectoderm: • Will form nervous system and outer skin • Endoderm: • Will form gut and digestive organs • Mesoderm: • Will form skeletal system and voluntary muscle • Blastula undergoes two processes • Gastrulation: • Invagination and cell migration cause ectoderm to surround embryo • Neurulation: • Ectodermal cells form the neural plate • Know: neural plate invaginates as neural folds push up becoming neural groove = central nervous system • Migration and specialization of cell lines • Leads to formation of primitive nervous system • Centered around “neural groove” • Brain is centered around anterior part of embryo • Central canal formation is a major developmental mile stone • Developmental Sequence: • Neural tube runs anterior to posterior along embryo • Surrounding ectoderm eventually encloses neural tube • When neural tube closes off brain and spinal cord are formed (21 days) • Primitive brain consists of 3 cavities that will form ventricles • Brain’s gross features are then formed through a series of bends • Goes through a series of folds or “flexures” • Gives rise to the compact structure of the brain • Brain, Diencephalon (thalamus), MB (brain stem)

“H-thymidine labeling

• Thymidine taken up by neurons during formation of DNA of cells • Cells undergoing division at time of injection get radiolabelled • Method for determining developmental timecourse: • H-thymidine labeling • Radioactive injection into embryo • So it can be imaged later in development

Neurogenesis

• Nearly all cells generated prenatally • Research has focused on the developmental timeline of brain cells • Timecourse of Corticogenesis: • In primates, begins during first quarter of gestation • All cells formed within 1 to 2 months after this process begins

Histogenetic timecourse

• Cortex develops from the inside out as cells adjacent to ventricles differentiate • Precursor cells: undifferentiated cells that will form glial cells or neurons • Cluster along ventricular walls • Migrate outwards on projections • Radial glia: • Cells which radiate outward from ventricular zone and guide cells on migratory paths • Project out from ventricular zones • Guides cells to developmental destinations (satellite vs astrocyte vs neuron vs etc) • Transform into astrocytes

Precursor cells, their division and migration

• Precursor cells: undifferentiated cells that will form glial cells or neurons • First 5 to 6 weeks of gestation cells divide in undifferentiated fashion in ventricular zones • Leads to exponential growth of precursor cells • After 5 to 6 weeks some cells differentiate into cells that will migrate while others stay behind • Cells that migrate will differentiate into different types of neurons while those staying behind form ventricular walls • Precursor Cell Division: • Three methods of division. They may divide into: • Brain cells • Brain cells and PC cells • PC cells • Cells migrate along radial glia

Correlational and experimental evidence for migration

• Type of neuron a cell will become is determined at genesis point • Two types of evidence support this hypothesis: • Correlational: • Determination of cell type correlated with time of creation during gestation • Evidence: different cell types formed at different times in gestation (graph) • Experimental: • Transplantation does not affect connectivity • Evidence: • Cells transplanted from one animal to another migrate to region of cortex determined by their creatine time • Cells prevented from migration still form connections consistent with their time-determined function • Suggests that cell’s function determined at time of creation

The Radial Unit Hypothesis

• Cortical neurons formed in ventricular zones • Radial glia project in an orderly fashion through cortical layers • Cells migrate along radial glia • Yields a topographic relation between cells formed adjacent to one another in ventricular zone • Cells born next to each other remain near each other in adult brain • Cells born remote to each other remain remote to each other in adult brain • Thus, columnar organization in cortex • “Cortical column” principal unit of cortical organization • Brain has a “laminar organization" • Brain may expand through increases in cell number, not in unit type

The Protomap Hypothesis

• Ventricular “protomap” determines functional variation • From this cortical - cortical connection forms • Protomap determines attraction of visual afferents to LGN, auditory afferents to MGN • Final role of cells appears to be determined by a complex interplay of genetic and environmental factors

Piaget’s theory

• A stage theory of cognitive development • General theoretical framework: “genetic epistemology” • A theory of how knowledge develops in humans • Genetic Epistemology: • A central concept: “cognitive structures” • Patterns of physical or mental action that underlie specific acts of intelligence • Correspond to stages of child development • Develop through 3 processes • Adaptation • Attempts to adapt to the world • Assimilation • Interpretation of events in terms of existing cognitive structures • Accommodation • Changing cognitive structures to make sense of the environment

Piaget’s developmental stages

• Sensorimotor: (0-2) • Object permanence NOT PRESENT (poor concept of objects in the world) • Unconnected • Integration achieved by relationship of sensory inputs to motor acts • Preoperations: (2-7) • Conservation of numbers/quantity and egocentric • Imagination and imitation • Concrete operations: (7-11) • Concrete (hands on) concepts able to solve in logical fashion and no abstract thinking • Able to classify • Understand reversibility • Formal operations: (12+) • Development of abstract thoughts and able to solve abstract problems in logical way • “Scientific” thinking

Neo-Piagetian research

• Rene Balliergeon • Tested Piaget’s theory about object permanence • Has found that 3.5 month olds are surprised or puzzled by the behavior of the car • Concludes that infants have more information about object permanence that piaget thought • Judy DeLoache: children’s ability to use symbols (mental representations of objects in the world) • Uses a scale model as a symbol of a real room • She finds that 2.5 year olds have difficulty with her task (find the big snoopy in the real room after seeing the little snoopy being hidden in model room) • But 3 y.o. Have no difficulties with the task • Gretchen Van de Walle: • Piaget argued that quantitative skills did not develop until around age 7 • More recent research however has shown that infants can distinguish differences in numbers of objects much younger • Gretchen Van de Walle studies quantitative ability in children • Showed 2 y.o. 2 trays • Tray with 2 vs 1 object was the “winning tray” (there was a prize in it) • Van de Walle than showed toddlers tray with 3 vs 4 items • Subjects reliably picked the tray with the greater number as the “winning tray” • Challenges notions of fixed stages of development • Cognitive abilities may be in place earlier than Piaget thought • Why the discrepancy? • May have resulted from developmental properties of PFC • Children may have difficulty performing behaviors that reflect their cognition • Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Behavior suggests “preservation” of responding • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

Contrast Piaget’s theory with those of the neopiagetians

• A stage theory of cognitive development • Do such stages actually exist? • Do they develop in the rigid fashion that Piaget suggested? • Babies as young as 3.5 months express surprise when the sequence of events suggest that the object has disappeared • Suggests that children exhibit “object permanence” much younger than what Piaget thought they did • Piaget argued that quantitative skills did not develop until around age 7 • More recent research however has shown that infants can distinguish differences in numbers of objects much younger • Challenges notions of fixed stages of development • Cognitive abilities may be in place earlier than Piaget thought • May have resulted from developmental properties of PFC • Children may have difficulty performing behaviors that reflect their cognition • Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

Performance-competence distinction

• Performance / competence distinction • May have resulted from developmental properties of PFC • Children may have difficulty performing behaviors that reflect their cognition • Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

Pointing vs. looking

• Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Behavior suggests “preservation” of responding • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

Object permanence studies

• Object permanence: know object is still there even when out of view • Rene Balliergeon • Tested Piaget’s theory about object permanence • Has found that 3.5 month olds are surprised or puzzled by the behavior of the car • Concludes that infants have more information about object permanence that piaget thought • Babies as young as 3.5 months express surprise when the sequence of events suggest that the object has disappeared • Suggests that children exhibit “object permanence” much younger than what Piaget thought they did

Symbol use studies

• Judy DeLoache: children’s ability to use symbols (mental representations of objects in the world) • Uses a scale model as a symbol of a real room • She finds that 2.5 year olds have difficulty with her task (find the big snoopy in the real room after seeing the little snoopy being hidden in model room) • But 3 y.o. Have no difficulties with the task

Ordinality studies

• Piaget argued that quantitative skills did not develop until around age 7 • More recent research however has shown that infants can distinguish differences in numbers of objects much younger • Gretchen Van de Walle studies quantitative ability in children • Showed 2 y.o. 2 trays • Tray with 2 vs 1 object was the “winning tray” (there was a prize in it) • Van de Walle than showed toddlers tray with 3 vs 4 items • Subjects reliably picked the tray with the greater number as the “winning tray”

stages from fertilization

• Fertilization to multicellular blastula • Blastula undergoes two processes • Gastrulation: • Invagination and cell migration cause ectoderm to surround embryo • Neurulation: • Ectodermal cells form the neural plate • Know: neural plate invaginates as neural folds push up becoming neural groove = central nervous system • Migration and specialization of cell lines • Leads to formation of primitive nervous system • Centered around “neural groove” • Brain is centered around anterior part of embryo • Central canal formation is a major developmental mile stone • Developmental Sequence: • Neural tube runs anterior to posterior along embryo • Surrounding ectoderm eventually encloses neural tube • When neural tube closes off brain and spinal cord are formed (21 days) • Primitive brain consists of 3 cavities that will form ventricles • Brain’s gross features are then formed through a series of bends • Goes through a series of folds or “flexures” • Gives rise to the compact structure of the brain

consequences of radial migration (be able to apply these principles)

• Cortical neurons formed in ventricular zones • Radial glia project in an orderly fashion through cortical layers • Cells migrate along radial glia • Yields a topographic relation between cells formed adjacent to one another in ventricular zone • Cells born next to each other remain near each other in adult brain • Cells born remote to each other remain remote to each other in adult brain • Thus, columnar organization in cortex • “Cortical column” principal unit of cortical organization • Brain has a “laminar organization" • Brain may expand through increases in cell number, not in unit type

fate of radial glia

• Radial glia: • Cells which radiate outward from ventricular zone and guide cells on migratory paths • Project out from ventricular zones • Guides cells to developmental destinations (satellite vs astrocyte vs neuron vs etc) • Transform into astrocytes

patient HM (Henry Molaison) (damage, resulting disfunction and function retained)

• Bilateral temporal lobe resection for treatment of epilepsy • Included removal of hippocampus and amygdala from both sides • Resulted in retrograde amnesia for the previous 10 years • Profound anterograde amnesia • Short-term or working memory normal • Taught us about the difference between declarative and nondeclarative memories • Declarative memories: involve the conscious recollection of events and information • H.M. Lost ability • Non declarative: (skilled memory) involves the ability to acquire and perform new behaviors H.M. • Tower of Hanoi

single unit recording (methods and characteristics)

• Extracellular: • Strongest signal obtained from closest cell • Filters used to wipe out weaker signal • Requires repetition to determine if signal is typical • Single unit recording intracellular: • Actual penetration of cell by micropipette • Requires fine control • Tolerance within a single micron • Blood pulse can change location • Can be used to determine the response characteristics of single cells • For instance Hubel and Wiesel used this method to map the response characteristics of primary visual cortex • Single cell recording permits observation of spike trains that correlate with stimulus presentation • Mapping of foveal-extrafoveal mappings in V1 • Mapping of ocular-dominance and orientation columns in V1 • … and functional mapping of specific brain regions (tonotopic mapping of primary auditory cortex)

2 processes from blastula -> embryo

• Blastula undergoes two processes • Gastrulation: • Invagination and cell migration cause ectoderm to surround embryo • Neurulation: • Ectodermal cells form the neural plate

neo-Piagetian psychologists and how their research contradicted Piaget’s theories

• Rene Balliergeon • Tested Piaget’s theory about object permanence • Has found that 3.5 month olds are surprised or puzzled by the behavior of the car • Concludes that infants have more information about object permanence that piaget thought • Judy DeLoache: children’s ability to use symbols (mental representations of objects in the world) • Uses a scale model as a symbol of a real room • She finds that 2.5 year olds have difficulty with her task (find the big snoopy in the real room after seeing the little snoopy being hidden in model room) • But 3 y.o. Have no difficulties with the task • Gretchen Van de Walle: • Piaget argued that quantitative skills did not develop until around age 7 • More recent research however has shown that infants can distinguish differences in numbers of objects much younger • Gretchen Van de Walle studies quantitative ability in children • Showed 2 y.o. 2 trays • Tray with 2 vs 1 object was the “winning tray” (there was a prize in it) • Van de Walle than showed toddlers tray with 3 vs 4 items • Subjects reliably picked the tray with the greater number as the “winning tray” • Challenges notions of fixed stages of development • Cognitive abilities may be in place earlier than Piaget thought • Why the discrepancy? • May have resulted from developmental properties of PFC • Children may have difficulty performing behaviors that reflect their cognition • Adele Diamond (1991) showed that 2 year old toddlers can learn to repeatedly reach for an occluded object • What site of occlusion changes toddlers will look to new location but reach to old location • Behavior suggests “preservation” of responding • Similar to “set-switching” deficit exhibited by frontal lobe patients • Similarity in behavior suggests common etiology: deficient frontal lobe activity

object permanence

• Object permanence: know object is still there even when out of view • Rene Balliergeon • Tested Piaget’s theory about object permanence • Has found that 3.5 month olds are surprised or puzzled by the behavior of the car • Concludes that infants have more information about object permanence that piaget thought • Babies as young as 3.5 months express surprise when the sequence of events suggest that the object has disappeared • Suggests that children exhibit “object permanence” much younger than what Piaget thought they did

fMRI (mechanism, strengths/weaknesses, uses, RF pulses, hemodynamic response, info captured by the images <- how)

• Strong magnetic field causes hydrogen nuclei to align in a common orientation • Short radio pulses from the head coil briefly realign these nuclei and then they return to their original alignment • Different tissues return to equilibrium at different rates • By detecting what frequencies come from different areas, we can determine the location of different tissue types and construct 3D brain images • Head coils: transmit-receive antennae • Takes advantage of the fact that neural activity is followed by blood flow in a highly predictable manner • Taken over time (can see brain while you are thinking about something) • Altered blood flow alters RF signal from active brain regions • Blood flow: HEMODYNAMIC RESPONSE (higher blood flow = higher need for oxygen thus activation) • fMRI can detect changes in the relative levels of oxygen in different areas of the brain • If certain areas show relatively higher levels of oxygen during certain types of tasks, we can hypothesize that these areas have something to do with that kind of thinking. We say that kind of task activates that area. • The time course of a voxel shown as percentage of mean intensity • Analysis software compares the model to each voxel and determine whether the fit is statistically significant • fMRI is non-invasive technique used to study the living brain • Generates high resolution functional images • Permits the examination of brain regions that become active during cognitive performance • Facilitates comparison of brain activity in younger and older • fMRI: temporal resolution not the best

contra-coup / brain injuries

• Contusion is blood leakage aka bruising • Example: frontal contusion • Skull fracture • Contra-coup • Closed head injury: MVC very common • Moving forward at high speed causing head to move forward hitting frontal lobe the hardest (snap back not as hard) • Hit via T-bone and moves head side to side hitting parietal lobe

Embryo development (cavities, flexures, gross structure, cell tissue layers, neurulation, gastrulation)

• Fertilization • Multicellular blastula develops (WILL BE ON EXAM) • Contains precursors of three main types of cell lines • Ectoderm: • Will form nervous system and outer skin • Endoderm: • Will form gut and digestive organs • Mesoderm: • Will form skeletal system and voluntary muscle • Blastula undergoes two processes • Gastrulation: • Invagination and cell migration cause ectoderm to surround embryo • Neurulation: • Ectodermal cells form the neural plate • Know: neural plate invaginates as neural folds push up becoming neural groove = central nervous system • Migration and specialization of cell lines • Leads to formation of primitive nervous system • Centered around “neural groove” • Brain is centered around anterior part of embryo • Central canal formation is a major developmental mile stone • Developmental Sequence: • Neural tube runs anterior to posterior along embryo • Surrounding ectoderm eventually encloses neural tube • When neural tube closes off brain and spinal cord are formed (21 days) • Primitive brain consists of 3 cavities that will form ventricles • Brain’s gross features are then formed through a series of bends • Goes through a series of folds or “flexures” • Gives rise to the compact structure of the brain • Brain, Diencephalon (thalamus), MB (brain stem)

Phineas Gage (damage, result)

• Involuntary resection of prefrontal cortex • Revealed important role of PFC in personality and numerous higher-order “executive” functions • Change in personality and higher-order “executive” functioning

lesion method (neuropsychology)

• The study of cognitive deficits following brain damage • The role of a missing brain region may be inferred from what the patient cannot do after it is removed • The Lesion Method: (does not accommodate neuroplasticity) • Logic is based on a localizationist perspective • An “additive factors” logic • Does not take into account the adaptive “parallel” nature of brain function

brain tumors

• A mass of abnormally growing tissue • No purpose or function • 3 major types: • Gliomas • Abnormal growth of glial cells • Meningiomas • Grow in meninges • Cause pressure on brain • Metastatic • Space occupying tumors

PET (mechanism, strengths/weaknesses, uses, info captured by images)

• Production of positron emitting isotope in a cyclotron • Chemistry of labeling compound with positron emitter and preparing compound in a form suitable for administration in humans • Transport of labeled compound from chemistry lab to PET lab • Administration (injection) of tracer compoun & data acquisition with PET camera • Processing of data from PET camera to extract information related to the tracer’s kinetics in the body • Interpretation of result • Positrons: • When a positron meets an electron the collision creates 2 gamma rays that have the same energy but go in opposite directions, • PET detects the gamma rays as they leave the pt’s body. • The information is fed to a computer and makes a picture • Depending on the type of tracer, different gamma rays are given off and detected. In this way multiple things can be evaluated • [18F]-labeled 2-deoxyglucose (FDG) is used to study glucose metabolism • [15O]-labeled water measures oxygen extraction. [15O]-labeled oxygen • [13N]-labeled ammonia can be used to measure blood flow • [11C]-labeled methionine and leucine can be used to evaluate amino acid uptake and protein synthesis • Measures glucose uptake to index neural activity • Good for ID disease of the brain • Wide range of NT it can detect • Diseases of the brain PET imaging can provide information to pinpoint and evaluate diseases of the brain. PET imaging can show the region of the brain that is causing pt seizures and is useful in evaluating degenerative brain diseases such as Alzheimer's, Huntington's, and Parkinson's. Within the first few hours of a stroke, PET imaging may be useful in determining treatment therapies. • Very expensive $$ • PET: middle (reasonably good spatial resolution) (not the best temporal resolution because time crunch due to radioactive substance) • Must inject radioactive ligands/ tracers for scanning • Poor spatial resolution • Often accompanied by MRI for more accurate localization

ectoderm, endoderm, mesoderm

• Ectoderm: • Will form nervous system and outer skin • Endoderm: • Will form gut and digestive organs • Mesoderm: • Will form skeletal system and voluntary muscle

precursor cells

• Precursor cells: undifferentiated cells that will form glial cells or neurons • First 5 to 6 weeks of gestation cells divide in undifferentiated fashion in ventricular zones • Leads to exponential growth of precursor cells • After 5 to 6 weeks some cells differentiate into cells that will migrate while others stay behind • Cells that migrate will differentiate into different types of neurons while those staying behind form ventricular walls • Precursor Cell Division: • Three methods of division. They may divide into: • Brain cells • Brain cells and PC cells • PC cells • Cells migrate along radial glia

assimilation (development of cognitive structures)

• Assimilation • Interpretation of events in terms of existing cognitive structures

Parkinson’s disease

• Lack of dopamine • Results from atrophy of substantia nigra • Substantia nigra responsible for production of dopamine

Huntington’s disease

• Caudate and putamen of basal ganglia degenerate • GABA levels reduced in basal ganglia • Ach also reduced

3H-thymidine

• Thymidine taken up by neurons during formation of DNA of cells • Cells undergoing division at time of injection get radiolabelled • Method for determining developmental timecourse: • H-thymidine labeling • Radioactive injection into embryo • So it can be imaged later in development

key measures of human performance in experimental psychology

• Stimulus -> cognition -> response • Basic units of measurement: • Reaction time • Accuracy • Much work has been done to establish the validity and reliability of these measurements

EEG (mechanism, strengths/weaknesses, uses, what does the image capture,

• EEG: good for high temporal resolution (low spatial resolution) • Temporally high-density recording • Critically depends upon trial-averaging • High temporal resolution • Maps based on known temporal, physical, and physiological properties of the head and brain • Event-related field maps • In combination with dipole technology can produce more precise localization • Tell inferences of consciousness (alpha v beta) (asleep v awake) (varying levels of consciousness)

lesion studies (single disassociation, double disassociation, inference problems)

• Single dissociation: • 1 patient group, 1 control group • 2 tasks • Difference between groups only occurs in Task A • Inference Problems with Single Dissociations: • Both tasks assumed to be equally sensitive to group differences • Single dissociation may result from general effects of trauma, not specific effect of lesion • Double dissociation: • [ NOT COVERED IN THE SLIDES ]

Rakic’s “protomap hypothesis” (ventricular zone)

• Ventricular “protomap” determines functional variation • From this cortical - cortical connection forms • Protomap determines attraction of visual afferents to LGN, auditory afferents to MGN • Final role of cells appears to be determined by a complex interplay of genetic and environmental factors

word superiority effect

• A target letter can be identified more quickly when it is imbedded in a word than when it appears among a random letter string • Can ID letter in word > than in random string of letters • In terms of speed and accuracy

microsurgical transplantation of cells during migration

• Transplantation does not affect connectivity • Cells transplanted from one animal to another migrate to region of cortex determined by their creatine time • Cells prevented from migration still form connections consistent with their time-determined function • Suggests that cell’s function determined at time of creation • Final role of cells appears to be determined by a complex interplay of genetic and environmental factors • This interplay studies by microsurgical experimental techniques • If cells implanted in region they are not meant to be they DONT GROW • If cells implanted in region they are meant to be they GROW • Experiment: • Somatosensory cortex barrels transplanted into visual cortex NO develop • Visual cortex cells transplanted into somatosensory cortex YES develop

Reeler mice experiment

• Genetic manipulation reorients radial glia • Neuronal organization disrupted • Laminar organization of cells is inverted • Mice demonstrate: • Reduced cerebellar volume • Ataxic gait • Dystonia • Tremors

topographic relations

• Yields a topographic relation between cells formed adjacent to one another in ventricular zone • Cells born next to each other remain near each other in adult brain • Cells born remote to each other remain remote to each other in adult brain • Thus, columnar organization in cortex • “Cortical column” principal unit of cortical organization

declarative (explicit) vs nondeclarative (implicit) memories – describe and give an example

• Declarative = semantic/episodic/explicit memory • Declarative memories: involve the conscious recollection of events and information • Example: remembering a historical fact • Nondeclaritive = how to do things, implicit, behavioral • Non declarative: (skilled memory) involves the ability to acquire and perform new behaviors H.M. • Example: riding a bike

neurogenesis

• Nearly all cells generated prenatally • Research has focused on the developmental timeline of brain cells • Timecourse of Corticogenesis: • In primates, begins during first quarter of gestation • All cells formed within 1 to 2 months after this process begins

cognitive structures (Piaget’s theory)

• Patterns of physical or mental action that underlie specific acts of intelligence • Correspond to stages of child development • Develop through 3 processes • Adaptation • Attempts to adapt to the world • Assimilation • Interpretation of events in terms of existing cognitive structures • Accommodation • Changing cognitive structures to make sense of the environment

neurodegenerative diseases (3)

• Alzheimer’s Disease: • Cause unknown • Progression runs posterior to anterior • Characterized by presence of cortical “amyloid plaques” • Memory loss early; executive, personality late • Pick’s disease • Cause unknown • Progression runs anterior to posterior (inverse of Alzheimer's) • Characterized by presence of cortical “pick’s bodies” (bundles of disorganized filaments) • Filaments composed of proteins • Huntington’s Disease: • Caudate and putamen of basal ganglia degenerate • GABA levels reduced in basal ganglia • Ach also reduced • Parkinson’s Disease: • Lack of dopamine • Results from atrophy of substantia nigra • Substantia nigra responsible for production of dopamine

Sternberg task (delayed response task) - reaction time pattern and indications about memory retrieval

• Reaction time increases monotonically with increasing memory set-size • Similar reaction time slopes for both “yes” and “no” responses • Shows string of letters and then single letter pops on screen and must say if it was part of string of letters or not • Delayed response task • Short Term Memory • Only ever responding to a single letter • “Serial exhaustive search” (Sternberg saw evidence of this) • Absence in yes / no response function they must sort through every item • Sequentially searching in memory for letters • Memory retrieval is a serial comparison process between items in memory and those in the world • Each comparison takes a fixed amount of time (msec) • Mental operations can be quantified in terms of the amount of time they take

Piaget’s developmental stages

• Sensorimotor: (0-2) • Object permanence NOT PRESENT (poor concept of objects in the world) • Unconnected • Integration achieved by relationship of sensory inputs to motor acts • Preoperations: (2-7) • Conservation of numbers/quantity and egocentric • Imagination and imitation • Concrete operations: (7-11) • Concrete (hands on) concepts able to solve in logical fashion and no abstract thinking • Able to classify • Understand reversibility • Formal operations: (12+) • Development of abstract thoughts and able to solve abstract problems in logical way • “Scientific” thinking

Rakic’s hypothesis (correlational and experimental evidence)

• Brain organization determined in ventricular zone • Predicts laminar organization of the brain • Ventricular “protomap” determines functional variation • From this cortical - cortical connection forms • Radiations determine laminar organization • Type of neuron a cell will become is determined at genesis point • Two types of evidence support this hypothesis: • Correlational: • Determination of cell type correlated with time of creation during gestation • Evidence: different cell types formed at different times in gestation (graph) • Experimental: • Transplantation does not affect connectivity • Evidence: • Cells transplanted from one animal to another migrate to region of cortex determined by their creatine time • Cells prevented from migration still form connections consistent with their time-determined function • Suggests that cell’s function determined at time of creation • Genetic manipulation reorients radial glia • Neuronal organization disrupted • Laminar organization of cells is inverted

Stroop efffect

• Subjects take longer to name a color word (red) when it is printed in a color that does not match the word • Multiple representations • “Privleged access” of some representations over others

Michael Posner letter matching experiments and implications for cognition

• “Are the 2 letters from the same vowel-consonant category or not?” • Results demonstrate that multiple representations are activated by a single stimulus • Reaction time decreases as time between letter presentations increases

Pick’s Disease vs. Alzheimer’s Disease (physiology and symptomology)

• Alzheimer’s Disease: • Cause unknown • Progression runs posterior to anterior • Characterized by presence of cortical “amyloid plaques” • Memory loss early; executive, personality late • Pick’s disease • Cause unknown • Progression runs anterior to posterior (inverse of Alzheimer's) • Characterized by presence of cortical “pick’s bodies” (bundles of disorganized filaments) • Filaments composed of proteins • Pick’s disease symptomology: • [ NOT COVERED IN THE SLIDES ]

structural MRI (high-resolution pictures of soft-tissues like brain) - how?

• Manipulates the behavior of Hydrogen protons to yield radio signal • Generates high resolution structural images • Takes advantage of the fact that different types of tissue produce different RF signals • The strong magnetic field causes hydrogen nuclei to align in a common orientation • Short radio pulses from the head coil briefly realign these nuclei and then they return to their original alignment • Different kinds of tissue return at different rates, sending different radio frequencies back to the antenna • By detecting what frequencies come from different areas, we can determine that location of different tissue types and construct 3D brain images • The nucleus of the H in water acts like a small bar magnet • Different tissues will return to equilibrium at different rates

What happens to PET spatial resolution when detector size decreases?

• The smaller the size of the detectors the better the spatial resolution of the PET syst