Chapter 7 Flashcards
What is fNIRS?
- Functional near-infrared spectroscopy
- Cortical tissue transmits light which allows for the imaging of oxygen consumption in the brain
- Oxygen consumption as a marker of neuronal activity in specific cortical regions
What is Broca’s region responsible for?
Speech production.
-Located in the left frontal lobe
What is a histological tool for studying neuroanatomy?
Brains were sectioned after death, and the tissue was stained with various dyes–> identify cell bodies viewed with a light microscope
- Light microscopes allowed for the division of the cerebral cortex into distinct zones based on neuron characteristics in those zones
- Modern microscopes image a fluorescent signal that is displayed by a neuron’s calcium levels when they are being fired in mice as they navigate their environment
What is the brainbow technique?
Technique discovered by Jean Livet involving labelling neurons by highlighting them with specific colours
(Think “Live the rainbrow”)
-Offers a way to describe where each neuron sends its signals & how it’s connected to other neurons
-Identify brain cells implicated in diseases
What is the dentate gyrus & what role does it play?
A subregion of the hippocampus which helps mammals remember the context in which they encounter information
-Deficits in these regions lead to memory deficits
-Without the hormone corticosterone, neurons in the dentate gyrus die
(Think “The dentist is a different context unless you’re courteous & masculine”)
Describe the study comparing memory formation of healthy rats vs ADX rats with their adrenal glands removed:
3 groups: healthy rats, ADX rats with no treatment, ADX rats with treatments that increase neuron generation in the dentate gyrus (better housing & longer running on wheels)
- Each rat was placed in context A or B for 10 mins on 2 days with each context containing ONE type of object
- 2nd condition was the same but this time with 2 diff objects (1 from that context & another from the other context)
- When healthy rats encounter an object in the wrong context, they spend 3/4 of their time investigating & treating the familiar object as new
- Non-treated ADX rats treated mismatched cases & other objects the same. Only spend half the time on each object
- Treated rats perform like healthy rats due to regeneration of dentate granule cells & were unimpaired in the object-context mismatch
- Therefore dentate gyrus is necessary for contextual learning
What is behavioural neuroscience?
- Study to understand brain-behaviour relationships
- A major challenge is to develop methods to study both typical & atypical behaviour
- Must develop ways to enable lab animals to reveal their symptoms
- Ethology (animal behavioural studies)–> basis for modern behavioural neuroscience
What is the Corsi Block-tapping test?
Participants observe experimented tapping sequence of blocks & must repeat the sequence correctly
- (Block span)–>Measures ST recall of spatial positions
- Increase task difficulty by finding out what their max block span is, then adding one more block (Span + 1)
- (Span + 1)–> measures learning & LT memory storage of info
What is the mirror-drawing task?
Person traces pathway (e.g star) by looking at mirror as your movement appears backward
- Increased accuracy with practice & show good recall after a few days
- People with memory deficits don’t recall learning this task, but still, perform it perfectly
What is the recency memory task?
Person is shown a long series of cards with 2 stimulus items (words or pictures)
- On cards with a question mark between them, they have to say if they’ve seen it before & which item they saw most recently
- May not be able to recall which item was seen most recently
- Or may not be able to correctly identify items as familiar
What is the navigation task devised by Richard Morris for analysis of rodent behaviour?
Place-learning task–>
-Placed in the pool at different starting locations & must find a platform
They can only do this by considering the configuration of visual cues in the room (e.g decorations, windows)
- Matching-to-place task–>
- The platform is placed at a different location on each test day.
- The rat must learn that the platform is placed on the same spot where it is originally found on that day, throughout the entire day.
- Landmark-learning task–>
- Must ignore room cues & focus on the only cue on the pool wall to find the platform
- Platform & cue move on each trial
- The rat must learn that distant cues outside the pool are irrelevant & only local cue is relevant
(Think “Morris the mouse at the pool”)
What is another behavioural study in rats to study role of movement in stroke?
- The rat must reach through a slot to get sweet food
- Taught to put their hands into the slot, rotate them horizontally to grasp, and rotate them vertically & then withdraw hands to get food
- Researchers observe digit dexterity during the video playbacks
What is the principal technique in animal studies when dealing with the brain?
- Inactivate the brain via lesions or with drugs
- Activate it with electrical stimulation, drugs or light
- Then measure brain function & performance
Describe Karl Lashley’s method of ablation
-Ablation is removing or destroying tissue
-Trained monkeys & rats on mazes & motor tasks–> removed bits of the cerebral cortex–> produce amnesia for specific memories
-The experiment failed because memory is distributed throughout the brain & not located in a single place
-Memory loss was related to the amount of tissue removed
(Think “Lash person is not able”)
What is a stereotaxic apparatus?
A device that permits the researcher to target a specific part of the brain for destruction
- Head is held in a fixed position
- 3D brain map created based on precise positioning of all brain regions relative to each other
- Dorsal-ventral (top-bottom) measurement is the y-axis made relative to the brain surface
- Medial-lateral measurement is the x-axis relative to midline junction of cranial bones
(“Think stereo audio surrounds your brain, taxes must be paid at a precise time, otherwise you’re financially destroyed”)
What is the most widely used surgical technique today for the treatment of Parkinson?
-Drill a hole in the skull & use stereotaxic coordinates to target globus pallidus
(Think “Parking globe”)
-Current passes through the globus pallidus through an electrode to destroy structure & relieve the patient of tremor
What is high-intensity focused ultrasound’s role in treating Parkinson’s?
- Achieve same result of hole drilling but without surgery
- Focused ultrasound points individual beams at the same spot in the brain
- The beam passes through tissue & tissue gets heated at convergent point of beams
- Heating that area makes it stop working properly–> surgeons will know they got the right target
- Heating continues until target is destroyed & tremor is eliminated
- The patient will start modifying behaviour to compensate for lesion & to prevent this, surgeons make reversible lesion techniques like regional cooling to prevent synaptic transmission
- In regional cooling, a chilled fluid is passed through a hollow metal coil that is placed next to the neural structure to keep it at 18 C
- Synaptic transmission is restored once the chilled fluid is removed from the coil
- If regional cooling is not an option, they’ll administer GABA agonists to prevent brain structure from communicating with other structures through local inhibition
Describe Penfield’s use of electrical stimulation during neurosurgery:
-Used electrical stimulation on cerebral cortex during surgery with the objective to enhance/block neuronal activity & observe behavioural effects.
(Think “Pen in a field that is cerebral cortex, pen being electrode”)
- Later studies did the same thing with stereotaxic instruments to place the electrode in specific brain locations
- Rats will engage in electrical self-stimulation by pressing a bar to turn on current shooting through their lateral hypothalamus in order to eat
- This current affects the neural circuit involved in eating & pleasure
How is brain stimulation used in therapy?
- Intact cortex adjacent to injured cortex after stroke is electrically simulated–> improvement in motor behaviours
- Deep brain stimulation (DBS)–> facilitate behaviour through the administration of continuous low-voltage electrical currents to a targetted area via electrodes implanted into the brain.
- DBS to globus pallidus in basal ganglia makes movements smoother for Parkinson patients
- DBS used to treat OCD, Schizo, Depression, epilepsy & TBI
