Neuro-Psych Midterm 1 Flashcards
Neuropsychology
The study of the relationship between brain function and behavior
It draws information from many disciplines, such as biology and physiology
Human Neuropsychology
How the brain (and nervous system) influence human behavior, cognition, and emotions
IMPORTANCE OF NEUROPSYCHOLOGY
Studies which area of the brain is associated with specific cognitive domains
- Can use lesion studies
Examines what happens to the brain with age and disease
- Examining development over time and different diseases (Alzheimer’s, autism)
Has implications in various fields
- Occupational therapy
- Education (IEP)
- Speech language pathology
Trepanation
The earliest evidence of interest in the brain comes from skulls with burr holes.
May have been used for relieving pressure, treating headaches, or mental disorders.
- Thought to be used to release “evil spirits”
Phrenology
Reading a skull to determine what type of characteristic traits or personality someone had.
Procedure: Felt for bumps or ridges
Problem: based on race/ethnicity bumps might be different, so this led to racism
Classic studies of neuropsychology
- Amnesia patients
- Split-brain patients
- Blindsight patients
- Lesion studies
Amnesia
Natural or surgical lesions in the medial temporal lobe that affected the ability to form and recall new memories.
Importance: Allowed researchers to identify the specific brain structures essential for memory (Temporal lobe associated to long term memory)
→ Showed that there are different types of memory
→ Provided evidence for memory consolidation
Split Brain
Involves surgically cutting the corpus callosum in people with epilepsy.
Importance: Lateralization/cerebral asymmetry:
○ Left hemisphere = involved with speaking
○ Right hemisphere = not involved with speaking
→ This work highlighted the importance of both hemispheres in cognition
→ Revealed that each hemisphere can independently perceive and process information
→ Showed how the two hemisphere communicate
Blindsight
Patients with damage to the visual cortex, resulting in loss of conscious visual perception in parts of their visual field.
○ Often result of a stroke
→ The information is still processed by other areas of the visual system that are still intact.
Importance: Provided valuable information of the association of vision and consciousness with the human brain.
→ Helped map visual pathways
→ Improved our understanding of brain plasticity
→ Provided insight for the study of consciousness
Lesion Studies
People who have damage to one hemisphere showed differing functional abilities.
Importance: These studies showed the specialized function of the cerebral hemispheres
→ Right hemisphere = drawing, puzzles, spatial skills, and navigation
→ Left hemisphere = language functions, reading, naming, arithmetic, control of voluntary movements
The job of neuropsychologists
- Expert diagnosticians
- Characterize cognitive strengths and weaknesses
- Link 1 & 2 to:
a. Select appropriate interventions
b. Estimate patient outcomes
c. Set goals
d. Direct to proper services
Central nervous system (CNS)
The brain is protected by the skull while the spinal cord is protected by the vertebrae
Peripheral nervous system (PNS)
Fibers that carry information to and away from the CNS
Somatic nervous system (SNS)
The part of the PNS associated with sensory and motor pathways
Has two parts:
1. Sensory pathways that bring information into the CNS (eg. skin receptors)(afferent)
- cannot be repaired
- Motor pathways that connect the brain and spinal cord to muscles (sending info out = efferent)
- can be repaired
Autonomic nervous system (ANS)
Subdivision of the PNS where the sensory and motor pathways influence the muscles of our internal organs
Dorsal
structures atop or within brain
- also known as superior
Medial
structures toward brainʼs midline
Lateral
structures located toward sides
Ventral
structures toward bottom of brain
- also known as inferior
Anterior
front
Posterior
back
Coronal slice
frontal view
Horizontal slice
dorsal view
Sagittal slice
medial view
Brain looks wrinkled with?
- clefts - can be fissure or sulcus
→ lateral fissures are deep enough to hit the ventricles; separates frontal and temporal lobe
→ central sulcus are not deep enough to hit the ventricles; separates frontal from parietal
- ridges - gyri
Frontal lobe
executive functioning
Parietal lobe
goal orientated movement
Temporal lobe
hearing, language, and music (encoding memory)
Occipital lobe
visual processing
Motor cortex
plan and control voluntary movements
- part of frontal lobe
Somatosensory cortex
sensory information
- part of pareital lobe
Forebrain
- Contains the cerebral hemispheres (cerebrum), basal ganglia, limbic system, thalamus, and hypothalamus
- Involved with many functions including mental activities, movement, emotion, and behaviors
Basal ganglia
involved with motor movements, executive functions, behavior, and emotions
Limbic system
involved with many functions like memory, emotions, and behavior
Diencephalon
Contains the:
1. Hypothalamus
- Controls the body’s hormone production
- Temperature regulation, feeding, sexual behavior, sleeping, emotional behavior, and movement
- Thalamus
- Channels sensory information travelling to the cerebral cortex from all sensory systems
The Midbrain
Contains neural circuits for:
- Hearing
- Seeing
- Orientating movements
- Pain perception functions
The Hindbrain
Cerebellum: plays a role in motor coordination, motor learning, and maintaining body equilibrium
Reticular formation: involved with sleep-wake behavior and behavioral arousal
Pons & medulla oblongata: controls vital body movements
The Brainstem
The bottom of the brain which connects the brain to the spinal cord
Regulates body functions & controls balance
Consists of midbrain, pons, and medulla oblongata
Reticular formation runs through it
Cerebral Connections
There are four main type of connections between regions:
1. Projections between one lobe and another
2. Projections within a lobe
3. Interhemispheric connections
4. Connections through the thalamus
CEREBRAL MATERIAL
gray matter & white matter
gray matter
- cerebral cortex (outer-most layer)
- folds in brain increase gray matter - more area for information and cognitive processing
- 40% of brain
- consists of nerve cell bodies (dendrites and axon terminal)
white matter
- deeper within brain (subcortical)
- 60% of brain
- made up of myelin and bundles of axons
- fatty molecule that provides insulation for axon
- involved in signal transmission
VENTRICLES
four ventricles are connected:
1. left lateral ventricle
2. right lateral ventricle
3. third ventricle
4. fourth ventricle
VENTRICLES AND CEREBROSPINAL FLUID
ventricles and subarachnoid space are filled with CSF
- CSF cushions brain and spinal cord, washes out waste, and delievers
nutrients
Ventricles are measure of atrophy
- loss of brain volume
- brain shrinkage → larger ventricles
CEREBRAL ASYMMETRY
both hemispheres are responsible for different functions
right and left hemispheres operate on contralateral sides of body
Cerebral lateralization
left hemisphere:
- language processing
- arithmetic
- analytical thinking
right hemisphere:
- visuospatial processing
- emotional processing
- holistic thinking
Cerebral asymmetry differences
- schizophrenia: reduced brain asymmetry (causes auditory hallucinations)
- dyslexia: bilateral language dominance
- handedness: left-handed individuals show bilateral language dominance
- sex differences: females show stronger left-sided language lateralization
SPINAL CORD
Extends from the bottom of the medulla
31 segments with spinal nerves
Supported by vertebra
Three main functions of the spinal cord
- Act as a pathway for impulses going to and from the brain
- Control automatic reflexes without consulting the high brain centers
- Control body movement and functions
Cranial nerves
12 pairs of cranial nerves in brain:
key part of nervous system - somatic nervous system
sense and motor impulses
- help you make facial expressions, move your eyes and process smells
Spinal nerves
31 pairs of spinal nerves:
facilitate voluntary motor control, sensory perception, and reflex responses
SPINAL NERVE CONNECTIONS
Posterior root: brings in sensory information
Anterior root: sends out motor information
White-matter: carries information to and from the brain
Branches: sensory neurons may influence motor neurons (e.g., spinal reflex arc)
AUTONOMIC NERVOUS SYSTEM- Sympathetic & parasympathetic
sympathetic division:
- body arousal
- fight-or-flight response
parasympathetic division:
- rest-and-digest
Electrical Messages
Also known as action potentials convey information form one area to another
Action potential steps
- neurons have resting potential (70mV)
- when threshold is reached (50mV), it becomes depolarized
- depolarization causes electrical spike
- membrane is then repolarized
- hyperpolarization occurs when neuron is in refractory period
- neuron is unable to be stimulated again - wave of action potential travels down axon
ELECTRICAL TO NEUROCHEMICAL MESSAGES
- synapses carry either excitatory or inhibitory messages
- involved with breathing, heart rate, cognition, and sleep
Presynaptic
membrane
encloses molecules that transmit chemical messages
Postsynaptic membrane
contains receptor molecules that receive chemical messages
Postsynaptic receptor
site to which a neurotransmitter molecule binds
Synaptic cleft
small space separating presynaptic terminal and postsynaptic dendritic spine
NEUROTRANSMISSION STEPS
- synthesis: neurotransmitters are transported from cell nucleus to terminal buttons
- release: transmitter is released across membrane by exocytosis
- receptor action:
transmitter crosses synaptic cleft and binds to receptor - inactivation:
transmitter is taken back into terminal or inactivated in synaptic cleft
NEUROTRANSMITTER CLASSES - three classes of neurotransmitters
- small-molecule transmitters: derived from food breaks down acetylcholine (ACh), amines, and amino acids
- neuropeptide transmitters: made through translation of mRNA from instruction in neurons DNA
- transmitter gases: synthesized in cell as needed
SMALL - MOLECULE NEUROTRANSMITTERS
Acetylcholine
Amines
Amino Acids
Acetylcholine
Essential for communication between motor neurons and muscle fibers
Key for “rest and digest”
Involved with learning and memory, arousal, and attention
Amines
Dopamine* – plays a role in movement, attention and learning, and in behaviors that are reinforcing
Serotonin* – involved with mood regulation, aggression, appetite, arousal, pain perception, and respiration
Norepinephrine – involved with alertness, arousal, attention, and the stress response
Epinephrine – also involved with the stress response
Amino Acids
Glutamate (Glu) – involved with learning and memory, motor function, pain perception, neuropsychiatric disorders
Gamma-aminobutyric acid (GABA) – associated with stress & anxiety, mood, sleep, and pain perception
Histamine – controls arousal and waking, and constriction of smooth muscles
NEUROTRANSMITTER CLASSES - BEHAVIOUR EFFECTS
cholinergic system (ACh)
- involved with waking behaviour, attention, and memory
dopaminergic system (dopamine)
- involved with coordinating movement, addiction, and mood regulation
noradrenergic system (NE)
- involved with emotions, hyperactivity and ADHD, and learning
serotonergic system (5-HT)
- involved with wakefulness, learning, depression, and schizophrenia
Anatomical Techniques
- x-ray (bones)
- conventional radiography - pneumoencephalography - angiography
- computed tomography (CT) - magnetic resonance imagine (MRI) (diagnosing conditions)
- structural MRI (sMRI)
- diffusion tensor imaging (DTI)
- magnetic resonance spectroscopy (MRS)
Conventional Radiography
X-rays pass through the skull (or body)
A shadowy image shows locations of different tissues (brain tissue = light grey, bone tissue = white)
Radiography is still used for examining the skull for fractures and the brain for gross abnormalities
This method is not the primary method for visualizing brain abnormalities
Pneumoencephalography
Advances traditional x-ray by taking advantage of the fact that x-rays are not absorbed by air
A small amount of CSF is removed from the spinal cord and replaced with air (spinal tap)
X-ray is taken as the air moves up the spinal cord and into the brain
Ventricles stand out because of the air
Pneumoencephalography advantages and disadvantages
Advantages:
- shows blockages and abnormalites
- brain tumors, hydrocephalis
Disadvantages:
- very invasive and painful
- high potential for morbidity and mortality
Angiography
A method for imaging blood vessels
- check how the blood is flowing through the brain and the health of the vessels
A substance that is absorbed by x-rays is injected into the bloodstream
Can be painful and dangerous
Computed Tomography (CT)
A narrow x-ray beam goes through the same object at many angles
- get a 3D image, and briefly exposed to radiation
The CT scan can localize brain tumors and lesions as they come up darker
Skull is white, grey and white matter are similar, and ventricles are dark
Computed Tomography advantage
In cases of brain trauma it’s much better than conventional radiology, you can see the ventricles and everything more clearly
Magnetic Resonance Imaging
A large magnet and a radiofrequency pulse generate a signal through the brain that produces an image
A hydrogen atoms nucleus consists of a single proton that align in the magnet. When many align in the same direction and can be summed
Proton density varies in different brain tissue therefore electrical currents differ depending on the tissue being examined
CFS, myelin, non-myelin atoms: all have different degrees of hydrogen atoms to allow use to see the different colours in the scan
Con: Patients Cannot go in scanner if have unremovable piercings or implanted metal though
Alzheimer’s MRI
much larger ventricles, a lot more black space = less overall brain volume
1.5T vs 3T vs 7T?
The number (e.g., 1.5) represents the strength of the magnetic fields
- 1.5T is the most common and widely available
- 7T is great for cutting-edge research but is not widely available
- 7T: good for seeing different sub-divisions, gives clear and crisp image
T1-weighted vs T2-weighted
T1w is great anatomical detail
- focuses more on the structure
T2w is great for detecting fluid-filled structures and edema
- focuses on the fluid (CFS build up in the frontal regions)
MRI vs CT scans
MRI
- CANT HAVE IT: People with pace-makers or cochlear implants
- MRI takes longer: on average 30 mins
- Common reasons for MRI: neurological conditions, headaches, trouble with vision, joint injury
CT
- CANT HAVE IT: Pregnant woman because of radiation for fetus, people under the age of 30
- 5-10 mins is length of the exam for most people
- Common uses: look at the head if people have chronic headaches, abdominal pain
Main difference between MRI and CT
Main difference is MRI uses strong magnetic filed to generate an imagine, CT uses radiation that generates through the body and is processed
Diffusion Tensor Imaging (DTI)
Detects the movements of water molecules to create virtual images of the brains nerve fiber pathways
A magnetic field is used to detect this water diffusion
Water molecules in nerve fibers follow the tract orientation moving in the direction of its longitudinal axis
DTI continued
Water molecules and nerve fibres are in the myelin, which allows us to see where the white matter is (the connections)
Different colours represent different representations
This method allows researchers and clinicians to study the structural connectivity between different brain regions and understand the organization of neural pathways
DTI can detect abnormalities in neural pathways and identify changes in fiber myelination
Has low signal-to-noise ratio
Arcuate pathway allows us to speak coherently
- If we have decreases in myelin (damage to the pathway) we might be slower at processing
DTI outcome measures
Fractional Anisotropy (FA) - reflects the directionality of water diffusion/displacement
Higher FA: more organized and coherent tracks (it’s good) (brighter colour)
- Brain regions are being connected at a higher rate
Low FA: potential tissue damage or disruption to the tracks
Mean diffusivity (MD) - reflects the average magnitude of water diffusion/displacement
High MD: is bad because there is a lot more water in the brain which can reflect swelling, inflammation and loss of neurons
Low MD: is good
Magnetic Resonance Spectroscopy (MRS)
Another MRI method to examine brain development, function, and disease
Used to look at the different metabolites in the brain
- NAA- most common metabolite: often observed where there’s neuronal loss
MRS varies the radiofrequency used for aligning the hydrogen protons
Can detect:
- Abnormalities in brain metabolism
- Brain-cell loss in degenerative disease
- Loss of myelin in demyelinating disease such as multiple sclerosis
Has limited special resolution and requires high concentration of the metabolite of interest to be reliably detected
Functional Techniques
Brain’s electrical activity
- Electroencephalography (EEG)
- Event-related potentials (ERPs)
Dynamic Brain imaging
- Position emission tomography (PET)
- Functional magnetic resonance imaging (fMRI)
- Optical tomography
Brain’s magnetic activity
-Magnetoencephalography (MEG)
