Flashcards in Chapter 7 Deck (94):
Functional Near-Infared Spectroscopy (fNIRS)
noninvasive technique that gathers light transmitted through cortical tissue to image blood-oxygen consumption, or oxygenated hemoglobin; form of optical tomography
study of the relations between brain function and behavior
8 or more similar cases and concluded that speech is located in the third frontal convolution of the left frontal lobe
Histological examination of brains
brains were sectioned postmortem and the tissue (histo) stained with differed dyes
makes it possible to image living brain tissue in a three-dimensional view
Parkinson's disease and the brain
early analysis of postmortem brain tissue showed that cells in the brainstem's midbrain (substantia nigra) had died
What happens if the substantia nigra is killed experimentally?
animals showed symptoms similiar to Parkinson's
necessary for remembering the context in which we encounter information
What happens if you prevent the growth of new hippocampal neurons?
leads to memory deficits
Hippocampus & Behavior
cellular changes in the hippocampus and behavioral changes are closely linked; hippocampal neurons are necessary for contextual learning to take place
Ultimate function of any brain region?
produce behavior (movement)
study of the biological bases of behavior
Corsi Block-Tapping Test
requires participants to observe an experimenter tap a sequence of blocks. The test is to repeat the sequence correctly (subject does not see the #, but remember the location of the blocks tapped)
What does the Corsi test measure?
short-term recall of spatial position (block span)
What does span +1 measure?
reflects the learning and longer-term memory storage of information
requires a person to trace a pathway, such as a star, by looking in a mirror. Motor task initially prove quite difficult because movements in mirror are backwards, but improve with practice
How do people with memory problems do on mirror-drawing?
They may not remember ever completing the task before, but they too show improvement
Recency Memory Task
participants are shown a long series of cards, each bearing two stimulus items that are words or pictures. Sometimes a ? appears between them and they have to indicate if they have seen the items before and if so which item they saw most recently.
the rat must find the platform from any starting location in the pool. The only cues available are outside the pool so the rat must learn the relation between several cues in the room and the platform's location
the rat has already learned that a platform always lies somewhere in the pool but is moved to a different location every day
the platform's location is identified by a cue on the pool wall. The platform moves on every trial, but the relation to the cue is constant.
has devised both novel tasks and novel scoring methods to measure the fine details of skilled reaching movements in rats
What does studying specific injuries in different regions tell us?
the function of the injured region AND what the remaining brain can do in the absence of the injured region
used ablation; trained monkeys and rats on mazes and motor tasks and then removed bits of cerebral cortex with the goal of producing amnesia for specific memories
What was the result of the Lashley studies?
memory loss was related to the amount of tissue he removed
a device that permits a researcher or a neurosurgeon to target a specific part of the brain for ablation. The head is held in a fixed position, and because brain structures hold a fixed relationship with the location of the junction of the skull bones, it is possible to image a 3d map of the brain
A small skull is drilled into the skull and an electrode is lowered into place. If a current is passed through the electrode the tissue in the region of the electrode tip is killed
Problems with electrolytic lesions
Neurons of the tissue and any nerve fibers passing through them are killed;
lower a narrow, metal tube (cannula) instead of an electrode, and infuse a neuron-killing chemical
slowness or absence of movement
dopamine agonist; relieves Parkinson's symptoms
acetylcholine antagonist; relieves Parkinson's symptoms
Rats with lateral hypothalamus stimulation
will eat when stimulated
when animals learn to press a lever to obtain a current; stimulation is affecting a neural circuit that involves both eating and pleasure
electrodes implanted in the brain stimulate a targeted area with a low-voltage electrical current to facilitate behavior
DBS and Parkinson's
can help make movements smoother by stimulating the globus pallidus (basal ganglia)
Transcranial Magnetic Stimulation (TMS)
noninvasive technique; small wire coil is placed adjacent to the skull. A high voltage current is pulsed through the coil, which in turn produces a rapid increase and subsequent decrease in the magnetic field around the coil that passes through the skull and causes neurons to depolarize and fire; Can be used to either induce behavior or disrupt ongoing behavior
dots of light that the participant will see if the visual cortex is stimulated
What if the motor cortex is stimulated?
movement is evoked OR is interrupted if movement was in progress
Can you stimulate brain activity with drugs?
Yes, drugs can pass into the brain through the blood stream and influence the activity of specific neurons in specific brain regions.
treats schizophrenia; reduces dopaminergic function and makes normal rats dopey and inactive (hypokinetic)
Advantages of administering drugs through the bloodstream?
effects wear off in time as the drugs are metabolized--> possible to study the effects of drugs on learned behaviors and then examine behaviors when drug wears off
How do repeated exposure to psychomotor stimulants like amphetamine, cocaine, and nicotine effect the brain?
long-term effects on the brain's later plasticity
transgenic technique that combines genetics and light to control targeted cells in living tissue, is based on the discovery that light can activate proteins (proteins can occur naturally or be inserted into the cell)
proteins derived from microorganisms, combine a light-sensitive domain with an ion channel. First one used as optogenetic technique was ChR2
when expressed in a neuron and exposed to blue light, the ion channel opens and immediately depolarizes the neuron, causing excitation
a green-yellow light activates a chloride pump, hyperpolarizing the neuron and causing inhibition
Fiber Optic Light and Optogenetics
can be delivered to selective regions of the brain such that all neurons exposed to the light respond immediately
measures the summed graded potentials from many thousands of neurons; related in time to a specific sensory event; recorded with a polygraph
graded potentials recorded with electrodes placed directly on the brain's surface
What EEGs show
1. EEG changes as behavior changes
2. An EEG recorded from the cortex displays an array of patterns, some of which are rhythmical
3. The living brain's electrical activity is never silent, even when asleep
When aroused, alert, or excited what does an EEG look like?
low amplitude and fast frequency
When calm and quietly relaxed what does an EEG look like?
rhythmical brain waves; alpha rhythms
extremely regular, with a frequency of approximately 11 cycles per second and amplitudes that wax and wane as the pattern is recorded, found in most people when they are relaxed with closed eyes
Advantages of ERPs
noninvasive; inexpensive; can be recorded from many brain areas simultaneously; detect not only which areas are processing particular stimuli, but also the order in which different regions play a role
How are ERP's analyzed?
Averaging numerous presentations to get a distinctive and more accurate wave presentation
magnetic potentials recorded from detectors placed outside the skull
Advantages of MEG
higher resolution than ERP; can more precisely identify the source of the activity being recorded
disadvantages of MEG
can record action potentials of single neurons with either an extracellular recording or an intracellular recording
can study a single neuron's electrical activity; inserting an electrode into the cell can kill it
neurons maximally responsive to specific locations in the world
x-ray approach (CT scan); a narrow x-ray beam could be passed through the same object at many different angles, creating many different images, and then the images could be combined with the use of computing and mathematical techniques to create a 3D image of the brain
CT scan interpretation
x-ray absorption varies with tissue density. High density tissue (bone) absorbs a lot of radiation(light colors). Low density material (ventricular fluid; blood) absorbs little (dark colors). images are in cross-section
the inability to speak fluently despite the presence of normal comprehension and intact vocal mechanisms
Magnetic Resonance Imaging (MRI)
technique that produces a static, 3D brain image by passing a strong magnetic field through the brain, followed by a radio wave, then measuring the radiation emitted from hydrogen atoms
MRI images are based on the density of the hydrogen atoms in different brain regions. Areas of the brain with high water content (neuron-rich areas) will stand out from areas with lower water content (axons)
Diffusion Tensor Imaging (DTI)
MRI method that detects the directional movements of water molecules to image nerve fiber pathways in the brain. can be used to delineate abnormalities in neural pathways and identify changes in the myelination of fibers (MS)
Magnetic Resonance Spectroscopy (MRS)
MRI method that uses the hydrogen proton signal to determine the concentration of brain metabolites such as N-acetyl aspartate (NAA) in brain tissue. Useful in detecting persisting brain abnormalities in brain metabolism in disorders like concussion
Dynamic brain imaging
measure the amount of blood, oxygen, and glucose the brain uses as subjects solve cognitive problems
How do you know if a region is active?
the amount of blood, oxygen and glucose increases
Functional Magnetic Resonance Imaging (fMRI)
magnetic resonance imaging in which changes in elements such as iron or oxygen are measured during the performance of a specific behavior; used to measure cerebral blood flow during behavior or resting
what can you tell when fMRI is superimposed on MRI?
fMRI changes in activity can be attributed to particular structures.
Disadvantages of fMRI
subjects must lie motionless in a loud noisy tube; restricted types of behavioral experiments
imaging method that measures changes in elements such as iron or oxygen when participants are resting (asked to look at a fixation cross and to keep their eyes open)
Positron Emission Tomography (PET)
imaging technique that detects changes in blood flow by measuring changes in the uptake of compounds such as oxygen or glucose; used to analyze the metabolic activity of neurons
electrons with a positive charge
How does PET measure blood flow in the brain?
the unstable radioactive molecules accumulate in the brain in direct proportion to the rate of local blood flow, which is related to neural activity because potassium ions released from stimulated neurons dilate adjacent blood vessels
greater the blood flow the higher the PET recordings
1. can detect decay of hundreds of radioactive chemicals which allows the mapping of a wide range of brain changes and conditions
2. can detect relative amounts of a given neurotransmitter, the density of neurotransmitter receptors and metabolic activities associated with learning, brain poisoning, and degenerative processes that might be related to aging
3. widely used to study cognitive function
a dynamic imaging technique that operates on the principle that an object can be reconstructed by gathering light that was transmitted through the object
Functional near-infared spectroscopy (fNRIS)
by measuring the bloods light absorption it is possible to measure the brain's average oxygen consumption
Advantages and Disadvantages of fNRIS
pros: easy to measure people throughout life
cons: light does not penetrate the brain very far (restricted to measuring cortical activity)
segments of DNA that encode the synthesis of particular proteins within cells
technique used to determine the chemical constituents of extracellular fluid; a catheter with a semipermeable membrane at its tip is placed in the brain and fluid flows through the cannula where it passes along the cell membrane
caudate nucleus and putamen of the basal ganglia
technique used to identify the concentration of specific chemicals in the brain as animals behave freely;
Brain-derived Neurotropic Factor (BDNF)
plays an important role in stimulating neural plasticity, and low levels are found in people with mood disorders like depression
associated with 11% reduction in hippocampal volume in healthy subjects; poor memory for events (episodic memory); dementia later in life
high incidence of neuroticism and anxiety
the way genes become active or not
can alter hippocampal organization and function via changes in gene expression
Does the same experience have the same effect on brain regions?
NO. the same experience changes different brain regions differently
Brain causes of ADHD?