Chapter 3 Flashcards
what are the two main approaches to studying the brain?
1.) Studying what happens when part of the brain isn’t working normally (normal vs messed up) → case studies, lesioning, electrical stimulation, magnetically deactivating
2.) Use fancy equipment to study not brain function and structure → CT scans, MRI, fMRI, PET scans, EEG, ERP, DTI
why are case studies used to study the brain?
when a stroke or injury damages part of the brain, we have a chance to see the impact on the mind
what is leisoning?
- surgical deconstruction of brain tissues performed on animals
- purposely doing surgery and destroying the brain to see what changes
what is electrical stimulation?
- parts of the brain and neurons can be stimulated electrically, chemically or magnetically
what is magnetically deactivating (TMS)?
a procedure in which an electromagnetic pulse is delivered to a specific region of the brain to temporarily deactivate that region (learn what these regions of the brain do)
what is computed tomography (CT)
when a computer constructs a 3D x-ray image from a series of 2D images
what is magnetic resonance imaging (MRI)?
- brain structure is mapped out using magnetic fields, produces a very clear picture
- different areas of the brain are made of slightly different molecule compositions (different densities) which have different magnetic properties
what is functional magnetic resonance imaging (fMRI)?
- relies on the fact that oxygen is sent to regions of the brain that are active
- fMRI scanner can measure differences in brain oxygen over a time while a person is completing a task (functional map is overlaid on structural map to get an overall map of how much each brain region is working on a given task)
what is positron emission tomography (PET scan)?
- allows us to see what part of the brain is active by tracing where a radioactive form of glucose goes while a brain performs a specific task
-prior to performing a task, the patient is injected with a substance and attaches a tracer to the glucose so it can be visualized - colours represent the most and least active parts of the brain
what is electroencephalogram (EEG)?
- a recording of the electrical waves sweeping across the brain’s surface
- useful for studying seizures (location) and sleep (stages, dreams)
- it is not spatially specific and cannot detect what part is active during a task
what is event related potential (ERP)?
- measuring the electroactivity in the brain and how it changes when presented with a stimulus
- requires many trials averaged over many EEG signals to remove the random fluctuations in the EEG signals
what is diffusion tensor imaging (DTI)?
a structural neuroimaging technique that allows researchers to measure white matter pathways in the brain
what are the two main categories of cells in the nervous system?
glial cells (white matter) and neurons (grey matter)
what are the 4 classes of glial cells?
astrocytes, oligodendrocytes, microglia, schwann cells
what are astrocytes?
- largest glia, star shaped, many functions
- protect CNS from pathogens
what are oligodendrocytes?
- myelinate axons in CNS
what are microglia?
- respond to injuries or disease
what are schwann cells?
- myelinate axons in PNS
what are the 5 components of a neuron?
dendrites, cell body, axon, myelin sheath, terminal buttons
what are dendrites?
- branching extensions that receive inputs from other neurons (where info is picked up from other neurons)
- very important in communication
what are cell bodies?
- contains the metabolic machinery that maintains the neurons (structures that keep neurons healthy and produce neurotransmitters)
what are axons?
- asingle process that extends from the cell body and represents the outburst side of the neuron
- carries the neurons messages from the cell body to the terminal buttons
what are myelin sheath?
- a type of glial cell that covers segments of the of the axon to insulate and speed neural processes
what are terminal buttons?
- stores neurotransmitters and release them (brain chemicals) into synaptic gap space
what is the central nervous system?
- brain and spinal cord
- makes decisions for the body
what is the role of the spinal cord in the CNS?
- most nerves enter/leave through spinal cord
- spinal reflexes do not involve the brain (body reacts before your brain is even aware)
what is the role of the brain in the CNS?
- number of brain structures control voluntary and involuntary behaviors
- two hemispheres: left and right with numerous structures in and beneath each one
what are the two divisions of the nervous system?
central nervous system (CNS) and peripheral nervous system (PNS)
what is the peripheral nervous system (PNS)?
- all neural pathways outside of the brain and spinal cord
- connect CNS with muscles, glands and sensory receptors
- sends and receives information to and from the rest of the body
what are the two subsystems of the PNS?
somatic and autonomic nervous systems
what are the components of the autonomic nervous system?
sympathetic and parasympathetic nervous system
what is the sympathetic nervous system?
arouses fight or flight, sympathizes with the situation
what is the parasympathetic nervous system?
calms (rest and digest), conserves resource, slow down body processes
what are the 3 main regions of the brain?
hindbrain, midbrain, forebrain
what is the main role of the hindbrain?
survival functions (breathing, reflexes)
what is the role of the midbrain?
sensation and action (picking up and relaying stuff to higher brain and body)
what is the role of the forebrain?
memory, thought and action (“higher brain functions”)
what are the components of the midbrain?
medulla, pons, cerebellum, reticular formation
what are the components of the midbrain?
substania nigra
what are the components of the forebrain?
thalamus, hypothalamus, pituitary gland, amygdala, hippcampus, basal ganglia, cerebral cortex
what is the role of the medulla?
autonomic survival functions like breathing, blood circulation, reflexes
what is role of pons?
- sleep and wakefulness
- coordinates automatic and unconscious movements like swallowing, posture, facial expressions, eye movements, sound localization
what is the role of the cerebellum?
- balance, coordination, and timing of movements (damage = jerky, uncoordinated movements)
- attention and emotion (damage = impulsivity, personality changes)
what is the role of reticular formation?
- a network of neurons that extend through the whole brain
- enables alertness and filters incoming sensory information (damage = coma)
what is the role of the substantia nigra?
- the nucleus from which dopamine neurons send their axons to the forebrain
- involved in movement control by receiving input from sensory neurons and motor areas and then sending to higher brain areas (damage = Parksinsons)
what is the role of the thalamus?
- the sensory switchboard
- all sensory messages (hear, vision, taste, touch) except smell are routed through the thalamus on their way to the cortex
- sends messages from the cortex to the medulla and cerebellum
what is the role of the hypthalamus?
- involved in drives and motivated behaviours like activity, thrust, hunger, sleep, sex (homeostasis)
what is the role of the pituitary gland?
- the ‘master’ gland of the endocrine system
- produces hormones that regulate other glands (thyroid, adrenal, reproductive)
what is the role of the amygdala?
- helps process emotions (fear and aggression)
- mediates memory formation for emotional events by telling hippocampus to remember the event as an important memory
what is the role of the hippcampus?
- processes continuous, episodic memories (what you ate for dinner, bday)
- important for the formation of new memories (without it, you can’t form new memories but you can remember old ones)
what is the role of the basal ganglia?
- functions in both voluntary movement and responses to reward stimuli
- helps control and coordinate movement (damage = tourettes)
what is the cerebral cortex?
- the outermost layer of the brain
- made up of mostly cell bodies (gray matter)
- has many folds to fit into the skull, allowing for more cortical structure and decrease axonal distance
- deep grooves define the 4 lobes found in each hemisphere
what are the 4 lobes?
occipital, parietal, temporal, frontal
what is the occipital lobe?
- processes visual information
- contains the primary visual cortex
what is the parietal lobe?
- processes body sensations and involved in spatial processing (“where”)
- contains the somatosensory cortex
what is the temporal lobe?
- processes auditory information and visual object perception (“what”)
- contains primary auditory cortex and Wernicke’s area
what is the frontal lobe?
- speech and skeletal motor functions
- contains the primary motor cortex, Broca’s area and the prefrontal cortex
what is the primary motor cortex?
- controls movement on opposite side of body
- laid out in a pattern represented by a motor homunculus
- the amount of cortical space devoted to each motor area is proportional to the sensitivity of the motor function (hands and mouth = more cortical space)
what is the somatosensory cortex?
- receives sensory information from opposite side of the body
- laid out in a pattern represented by a sensory homunculus
- the amount of cortical space devoted to each sensory input is proportional to the sensitivity of the sensory function (fingers, mouth = more cortical space)
what is the role of glutamate?
-used by most neurons in the CNS and PNS anytime you see, smell, hear, taste or move your body
- most widely distributed excitatory neurotransmitter
what is GABA?
- most common inhibitory neurotransmitter
- ised by approximately 30% of neurons in the brain
what is the role of Acetylcholine (ACh)?
involved in memory and muscle activity
what is the role of norepinephrine?
important for mood stability and arousal (depression)
what is the role of serotonin?
influences mood, eating, sleep, and sexual behaviour (OCD)
what is hemisphere lateralization?
the fact that each hemisphere of the brain performs somewhat different functions
what are the right and left hemispheres responsible for?
- Left Hemisphere: language, mathematical, logical abilities, positive emotions
- Right Hemisphere: spatial relations, music, facial processing, negative emotions
Left visual field is processed in right hemisphere
Right visual field is processed in left hemisphere
what is resting potential in neural communication?
- if an axon is not sending or receiving g any signals, then it is negatively charged (-70mV)
- the inside of the neuron has more negative charged than the outside
what are the 2 main reasons for the negative charge when a neuron is in resting state?
1.) concentration gradient - the tendency for molecules is to distribute themselves evenly in their environment and move from [high] to [low]
2.) electrostatic pressure - ions will attract or repel each other depending on their electric charge
what are 3 main players in neural communciation?
- organic ions (A-) are stuck inside the cell
- potassium ions (K+) flow relatively freely, concentration gradient wants to push them out of the cell (high to low) but electrostatic pressure wants to keep it inside the cell (+ and - attract)
- sodium ions (Na+) are concentrated outside of the cell and electrostatic pressure and concentration gradient want it to go in, but Na+ doors don’t open well so it is stuck outside
what are the steps to action potential?
- first, the membrane must depolarized, or made less negative (10 or 20mV)
- if threshold is reached (depolarization reaches a certain level), then Na+ channels open
- cell’s electric charge becomes significantly more positive (+40mV)
- voltage gated sodium channels close until cell returns to resting state
- potassium channels also open, but with more of a lag
- concentration gradient and electrostatic pressure work harder to force K+ ions outside of the cell
- the cell becomes hyper-polarized (more negative -80mV)
Cell closes and returns to resting
what is the all-or-none principle?
once a neuron’s electrical charge reaches threshold and an action potential is triggered, the action potential will always occur with the same strength
