Drain Damage and the Mind Review

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  • Topic: Brain, Visual system, Retina
  • Pages : 17 (3686 words )
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  • Published : May 7, 2013
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Science = boat
- continually rebuild while trying to stay afloat
-phil/scientist…psych/nero same boat
-psych- info about mental models
-but psych needs to be constrined by knowledge of the brian
-psych- can be more functional
-but study of brain alone = not enough about mind
-psychologicl and phenomenicallevels need to be examined aswe Return to smith intro notes
-unerstand neuro cognitive operations and consciousness
-combo of operations
-experiencene, naural events, cognitive events +behavior

Acuity- sharpness/clearness of perception
-visual acuity varies with eccentricity (distance from center)
-mascular degeneration

2-point discrimination- ability to tell that 2 objects touhing skin are 2, not 1
-the closer together, the harder it is to tell
-easiest on lips/finger- where touching happens the most

Zemans description of “biological splendor of the brain…an ingenious microcomputer…bursting with life”

-brain = 100 billion neuron
-neocortex- 80% of the brain
-unfolded- big surface area

-neuroimaging techniques- x-ray CT, MRI, PET, post-modern histology

Return to jan 8 lecture

Neurons
-excitable cells
-sensory neurons/motor neurons
-send and recive info via electrical/chemical signals
-sourrounding bilayer of lips (w protiens) electrical insulator
-ion channels- allow charged ions to flow in and out
-voltage gated-can be open/closed via altering voltage diff across membrane
-other chemically gated
-ion pump- transport ions from one side to other
Synaptic transmission
1. a presynaptic neuron releases neurotransmitters that bind and activate the receptors of another neuron
-Resting potential- realtivley static, consistent membrane potential of a neuron
-passive electrical currents flow in and out
-about -70mV
2. action potential is initiated in the presynaptic neuron
Action potential- triggers neuron communication
-short-lasting event where the electrical membrane potential rapidly rises/falls
-voltage chemicals trigger it
Postsynaptic potential- (larger/long term action potentials)
-The changes in membrane potential in postsynaptic receptors resulting from the release of a neurotransmitter
-graded input singal:
Excitatory postsynaptic potential
-if opening of ion channel results in a net gain of pos charge across the membrane
-the membrane is said to be depolorized bc the potential comes close to zero
-EPSP brings the neurons potential close to the firing potential (-50mV)
Inhibitory Postsynaptic Potential
-opening of ion channel result sin net gain of negative charge
-moves the potential farther away from firing potential
-membrane is hyperpolarized- it is more negative

Feedback inhibition-  increased firing of the principal cell elevates the interneuron’s discharge frequency which, in turn, may decrease the principal cell’s output -regulatory mechanism /reduces further activity

Lateral inhibition- ability of an excited neuron to reduce activity of its neighbors -monosynaptic reflex- requires only 1 sensory neuron and 1 motor neuron
-single chemical synaps
-stretchmuscle contraction
-brief simulation to X muscle results in contraction of Y muscle

Neurons in Retina
Rod- neuron that is sensitive to light aka photoreceptor cell
-dim light vision/black/white vision
-most useful at night, when light energy is reduced
-little use during day- replenishing photo pigment takes time Cones- photoreceptor cell/neuron
-daytime vision/color vision  
- use photo pigments that can be generated rapidly
- differ in the sensitivity of their photo pigments to different wavelengths of visible light
-high acuity.
-Rods and Cones- not distributed equally throughout the retina
-Cones- densely packed near the center called fovea, of the retina fewer far out   Ganglion cells- photoreceptor cells
-transmitts image-forming and non-image forming visual info to several regions in the brain...
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