Neuroscience II Flashcards
What is the neuraxis?
Nervous system axis
True or false: the neuraxis goes straight up and down from the top of your neck to your toes
False
It curves at your head
What does “dorsal” refer to?
The back of the neuraxis
What does “ventral” refer to?
The front of the neuraxis
What does “rostral” refer to?
The top of the neuraxis
What does “caudal” refer to?
The bottom of the neuraxis
What do you call regions that are more central of the brain?
Medial
What do you call regions towards the outside of the brain?
Lateral
Where is the rostral ventral medial medulla located?
Towards the top (rostral)
In front of the neuraxis (ventral)
Towards midline of the brain (medial)
Describe the case study of Phineas Gage
Gage was a foreman of a railway construction crew. He was very kind and respected by his fellow crew-mates
One day, he was in an accident which resulted in the blasting of a three foot iron rod completely thru the top of his skull
Tho he recovered, his personality changed. He was now selfish, angry, etc.
Shows that the brain has specialized structures for complex behaviour
What is a limitation of case studies like Phineas Gage’s?
Rarely isolated to specific structures; makes a more difficult task of assigning impaired function to specific brain areas
How can you overcome the limitations presented by case studies (i.e. the ones in Phineas Gage’s)?
By studying specific brain lesions in animal models
Researcher removes a defined brain region and observes the result on behaviour
How accurate are lesion studies?
Depends on the precision of the lesion
Even so, bc brain is highly connected, a variety of behaviours can be affected by a single lesion
What is another approach to studying the brain, besides lesion studies?
Targeted electrical stimulation:
Electrically stimulate an area of the brain and observe the result on behaviour to build an anatomical map related to function
Which method of studying the brain did Dr. Wilder Penfield use as he performed brain surgery to treat patients with epileptic seizures?
Targeted electrical stimulation
Describe Wilder Penfield’s “Montreal Procedure”
A patient undergoing surgery would be under local anaesthetic and fully conscious (since the brain itself does not have pain receptors). They worked with Penfield to locate and remove the scarred tissue
Used a thin, carrying a small electrical charge to stimulate the cortex —> individual neurons fire —> patient gives observations –> accurately map perceptual processes to brain regions
How would Penfield know if an area of the visual cortex was stimulated [from his “Montreal Procedure”]?
If the patient reported seeing flashes of light when that area was stimulated
Describe the single cell recording procedure
Small electrode inserted into nervous tissue of a live animal model with its tip held just outside the cell body of an individual neuron.
Neural activity recorded while animal performs a task or a stimulus is presented. Pattern of firing reveals a PARTICULAR/individual neuron’s functional role
How did Hubel and Wiesel use single cell recordings in cats?
Presented cats with specific visual stimuli while recording from single cells in the visual cortex. Individ cell types were identified that responded to specific categories of visual stimuli
What do scientists use to study large-scale structure and function of brain regions?
Structural neuroimaging:
- CT
- MRI
Functional neuroimaging:
- PET
- fMRI
- EEG
What does CT stand for?
Computed tomography
What happens during a CT scan?
Series of xray slices of the brain are taken and pieced together to produce a quick and inexpensive pic of the brain
In what instance would you use a CT scan?
Diagnose brain injuries
What’s a limitation of CT scans?
Low res; difficult to examine fine brain anatomy
What does MRI stand for?
Magnetic Resonance Imaging
What happens during a MRI scan?
Powerful magnetic fields are generated and align the hydrogen atoms found throughout the brain; can localize tissue very precisely
What does PET stand for?
Positron Emission Tomography
What happens during a PET scan?
Radioactive tracer of glucose or oxygen is inserted into the bloodstream. Molecules make it to the brain and are used in metabolic processes, which are detected by the PET scan.
More active areas will use more metabolic resources –> image of brain’s relative pattern of activity can be constructed
In what instance would you use a PET scan?
To learn how brain function relates to cognitive tasks such as language and memory (cognitive scientists use this a lot)
What’s a disadvantage of PET scans?
Req a radioactive tracer to be injected (invasive procedure)
How does fMRI work?
Measures the blood oxygen dependent signal; measures the relative use of oxygen throughout the brain
More active areas will use more oxygen/metabolic resources
Why are fMRIs preferred over PET?
Less invasive
What’s a limitation of fMRIs?
Provides a rough image of brain activation. Oxygen use spikes a few seconds later than the spikes of activity in the brain
DON’T USE if interested in precise timing of brain activation and function
What does EEG stand for?
Electroencephalogram
How does EEG work?
Electrical activity of brain recorded thru scalp by cap of sensitive electrodes; provides rough pic provided by families of neurons
How can you make the EEG more informative?
In event related potential experiment, specific stimulus presented repeatedly while EEG is recording. Stimulus has a small and consistent reading that can be averaged out after many trials. This balances the noise usually made by EEG.
Even after balancing the noise in EEGs, the ERP signals are still difficult to interpret. How do they usually have to interpret most signals? Provide an example
Number of signals serve as markers for diff neural processes
Ex. N170 wave corresponds to face processing
What does the hindbrain consist of?
Medulla
Pons
Reticular formation
Cerebellum
The structures in the hindbrain are responsible for the regulation of vital bodily functions. Why is this not surprising?
Evolutionarily the oldest parts of the brain; found in nearly ever vertebrate species
What does the hindbrain do/where is it located?
Located at base of the skull, connects the brain to the spinal cord
What is the function of the medulla?
Regulate:
- breathing
- digestion
- heart rate
What is the function of the pons?
Has a role in:
- movement
- auditory perception
- emotional processing
What is the function of the reticular formation?
Has a role in:
- arousal and motivation
- circadian rhythm
- posture and balance
What is the function of the cerebellum?
Coordinated movement
Where does the midbrain lie?
Between the hindbrain and the forebrain
What are the two major subdivisions of the midbrain?
Tectum
Tegmentum
Which two structures does the tectum contain?
Superior and inferior colliculi
What functions of the two structures in the midbrain responsible for?
Functions related to perception and action
What is the superior colliculus involved in?
Eye movements
Visual reflexes
What is the inferior colliculus involved in?
Auditory integration
Which structures does the tegmentum contain?
Red nucleus
Substantia nigra
What functions is the red nucleus (in the tegmentum) involved in?
Motor control
What functions is the substantia nigra (in the tegmentum) involved in?
Reward-related behaviour (thru release of dopamine)
What functions is the forebrain responsible for?
Complex functions:
- emotion
- memory
- perception
- thought
What are the two sections of the forebrain?
Limbic system
Cortex
What are the stuctures in the limbic system?
Hypothalamus Pituitary gland Thalamus Amygdala Hippocampus
What is the function of the hypothalamus?
Integrative functions:
- directing stress-related reponses
- regulating energy metabolism by influencing feeding, digestion, metabolic rate
- regulating reproduction thru hormonal control of mating, pregnancy, and lactation
(Fight, Flight, Feeding, and Reproduction)
How does the hypothalamus exhibit its regulatory roles?
Thru neurons that are capable of producing a variety of regulatory hormones and via connections with pituitary gland, etc.
What are the two subregions of the pituitary gland called?
Anterior and posterior
What is the overall function of the pituitary gland?
To control the endocrine system
What is the function of the anterior pituitary gland?
Recieves signals from brain and releases stimulating hormones to regulate important endocrine glands (thyroid, testes, etc.)
What is the function of the posterior pituitary gland?
Extension of the hypothalamus and releases oxytocin and vasopressin
What is the role of oxytocin?
Lactation
Uterine contractions in women
Contributes to bonding, love, trust
What is the role of vasopressin?
Blood hormone that regulates thirst by interacting with kidneys to regulate glucose levels
What is the function of the thalamus?
Axons from every sensory modality synapse in the thalamus. Thalamus processes and relays info selectively to areas of the cerebral cortex
Output from cerebellum and limbic system first relay thru thalamus on its way to cortex
What is the function of the amygdala?
Receives sensory info and decodes emotions (especially stimuli that may be threatening)
During intense emotions, amygdala becomes very active
When the nuclei of amygdala are damaged, what happens to animals?
Animals show deficits in classical conditioning of fear responses; relates to post-traumatic stress disorder
What is the function of the hippocampus?
Memory
- Activity in this region associated with ability to retain short term memories and ability to turn short turn memories into long term memories
Ability to navigate
- maintains a ‘spatial map’ of the world around you
What is special of about the hippocampus? (neurogenesis)
In this region, neurogenesis continues throughout adulthood; helps with memory
How is the hippocampus related to Alzheimers?
Extreme trauma to the region leads to severe amnesia
Why are strong emotions triggered by particular memories?
Bc hippocampus is connected to amygdala
What are gyri and sulci?
Gyrus = bulge outward on the cortex (ridges) Sulcus = gap between the bulges (indents)
Why is the purpose of gryi and sulci/ why is the cortex folded?
Increase the surface area of the cortex
What are fissures?
Very deep sulci; often divide major areas of the cortex
What are the four diff lobes of the cortex and where are they located?
Frontal
Occipital - back
Parietal - between frontal and occipital
Temporal - wraps around both sides (near temple)
What is the function of the occipital lobe?
Visual processing; more complex visual processing begins here
A person with healthy eyes but a damaged Occ lobe will be blind
What is the function of the temporal lobe?
Processing form and identity of visual stimuli
Location of primary auditory cortex; auditory processing begins here
Partially responsible for memory and language
Individ with severe temporal lobe damage may display what symptoms?
Deficits in process of speech, amnesia, and auditory processing
Where is the sylvian fissure?
Above the temp lobe
What is the function of the parietal lobe?
Primary somatosensory cortex lies here; processing of touch begins
(Thru projections from occiptal lobe) it processes the location and movement of visual objects
Contains a spatial representation of the world that may be involved in visual attention and guiding eye and body movements
What are some consequences of damaging the parietal lobe?
Loss in sensation completely
Deficits in:
- orientation
- attention
- coordination of targeted movements
- somatosensory processing
Complete loss of attention to particular spatial regions
Where does the primary somatosensory cortex lie?
Directly along central sulcus, at connection point with frontal lobe
Where does the primary motor cortex lie?
Along central sulcus, where front lobe meets parietal
What is the function of the frontal lobe?
Motor processing
Complex decision making processes occur here
Language
Inhibition
Manipulation of items in short term memory
Individ with damage to the frontal lobe display which symptoms?
Trick question: depends on specific area of lesion
How does the behaviour of young children mirror the state of the developing front lobe?
Children have a lack of inhibition, underdeveloped social skills, and forward planning — their frontal lobe is still developing
What is brain lateralization?
Function specialized to one side of the brain
How could you conclude that a particular cortical region has a unique function on only one side of the brain?
Lesion studies:
- Damage to a specific cortical region on one side of the brain produces a specific behavioural deficit whereas damage to the other areas do not lead to the same behavioural deficit
Describe the case study done by Paul Broca
“Tan” suffered from a speech deficit known as aphasia. “Tan” was one of the few words that he could articulate
Broca discovered a lesion in the left frontal lobe (Broca’s area). This area is vital for the motor production of speech
What did Wernicke note about language deficits?
Noted that some are not motor production problems but rather, deficits in language comprehension
What is Wernicke’s Area?
Left temporal gyrus
An area important for language comprehension
Language processing is lateralized by which hemisphere?
The left one
What is the right hemisphere involved in processing?
Spatial representations of the world
Why is lateralization of the brain not noticeable by humans?
Because the corpus callosum (thick bundle of axons) passes thru the centre of the brain and joins the two hemispheres together
What is Split Brain Syndrome?
In normal patients, info crosses over from one side of the body to the contralateral/opposite side of the brain via the thalamus. Normally, this info is also available to the ipsilateral/same side hemisphere by corpus callosum.
In SBS, info is unable to travel to the other hemisphere bc the corpus callosum is severed.
Why are split-brain individuals usually relatively unaffected?
Bc stimuli in the world are percieved bilaterally
A split-brain patient stares straight ahead at a fixation point. You present a pic of a cup to the left visual field. If you ask her to name the object she saw, what will she say? Why?
She will be unable to do so because language is processed by left hemisphere of the brain and only the right hemisphere percieved the cup
A split-brain patient stares straight ahead at a fixation point. You present a pic of a cup to the left visual field. If you ask her to close her eyes and feel thru a set of objects to feel the one that she was presented with, what would she do?
She would have no problem picking the object as this is a distinctly spatial task (and spatiality is processed by the right hemisphere– the one that perceived the cup)
A split-brain patient stares straight ahead at a fixation point. You present a pic of a cup to the right visual field. You ask her to name it it and to pick it out while blindfolded. What will she do?
She’ll be able to name it but she won’t be able to pick it out
