Final Exam Flashcards
Retina
Light-sensitive tissue at the back of the eye
Fovea
Location of maximum visual acuity (aligned with center of cornea
Optic Disk
Where optic nerve exits the eye (causes blindspot)
Rods
-More numerous
-Low-light vision
-cannot distinguish colors
-do not respond to red
Cones
-Color vision
-require more light
-Sensitive to red, blue, and green
Rods Location
Outside fovea
Cones Location
In fovea
Photopic vision
Daylight vision (cone-based)
Scotopic vision
Night-time vision (rod-based)
Retinotopic maps
Parts of the visual field that are near each other are presented by neurons near each other
V1
-Primary Visual cortex
-Responds to lines of a specific direction
-Neurons have different receptive fields which have to line up for excitation
Ocular Dominance Columns
-There is still separation in the left and right eye in each hemisphere separating the same hemifield
-Combination of nature (genetic map) and nurture (experience)
-Born blind in one eye=no ocular dominance columns
-Born blind in both eyes=ocular dominance columns are present
Purpose of Pain
A protective mechanism to warn us before permanent damage occurs
Thermal nocieptors
-Activated by extreme cold (< 41degrees)
-Activated by extreme heat (>113 degrees)
Mechanical nociceptors
Activated by strong pressure applied to skin
Chemical nociceptors
Activated by certain chemicals
Polymodal nociceptors
Activated by:
-Intense temperatures
-noxious chemicals
-intense mechanical signals
A range of different things; a more dull pain
Myelination in pain pathways
-Thermal and mechanical nociceptors: Myelinated and non-myelinated
-Chemical and polymodal nociceptors: non-myelinated
Why are some pain pathways non-myelinated?
Pain is one of the oldest systems and predates myelination
How pain is mediated
-By pathways in the spinal cord
-Deep brain stimulation
-opiates as inhibitors
-Pain is sort of an illusion and can be modulated with different techniques
NMDA receptors
-Cell needs to be sufficiently depolarized and a glutamate neurotransmitter needs to bind to the receptor
-Helps strengthen connections for memory
-Neurons that fire together wire together
Semantic memories
Remembering facts that aren’t tied to an experience
Procedural memories
-Like riding a bike or tying your shoe
-Requires repeated exposure
-Not necessarily tied to memories or describable
-Doesn’t use hippocampus
-Encoded in motor pathways
Episodic memories
-Memory of events
-formed in hippocampus but stored in cortex
Memory damage
-Semantic: can’t remember facts
-Procedural: can’t remember how to do things like put on a shirt
-Episodic: lose recent episodic memories and prevent you from forming new memories
Hippocampus
-Involved in learning and memory
-Critical for formation of new memories, but not retention of old memories
-Old memories moved to cortical regions
Amygdala
-Reciprocal connections with hippocampus
-involved in memory and emotional reactions, particularly fear
-strong emotional events tend to form very strong memories
Role of forgetting
-Forgetting allows generalization
-Generalization allows you to recognize that two situations are similar
-Can transfer generalization from one situation to the next
How neural prostheses work
-Electrical current stimulates or inhibits neural activity
-Work is being done on adding chemicals to encourage neurons to grow towards electrical devices
Deep Brain Stimulation
-Stimulates the basal ganglia, stimulating the region that’s normally missing due to loss of dopaminergic neurons, stimulating more neurons in that pathway
-For Parkinson’s patients
Retinal Implant
-Allows 20/1260 vision (legal blindness is 20/200)
-Patients learn to interpret visual patterns sent to the brain
-Retinal camera is mounted on glasses
-Patients move their head around to capture a visual scene
Vestibular impalnt
-Skips normal process by directly stimulating the vestibular nerve
-For patients without a working vestibular system
-Not yet clinically available
Cochlear Implant
-For those with lost or damaged inner hair cells
-Circumvents hair cells and directly stimulates auditory nerve
-Provides sensation of hearing; but not normal hearing
-You can measure electrically-evoked compound action potentials (corresponds to wave I of the ABR
-
Evidence for place and temporal coding
-Location of electrode stimulated determined by the frequency of a sound
-You can stimulate place of electrode or rate in cochlear implant to increase pitch
Limits of number of electrodes used in cochlear implants
-Current spread: Electrical fields will start interacting, even if electrodes give independent information.
-The more electrodes you put in, the closer together they get, the more you get a smearing effect.
-Distortion effect from electrical fields interacting between different electrodes, as well as what’s happening at the neural level
