psy 201 midterm2
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- when does action potential occur
-
*Phases of action potential:
1)resting
2)Depolarizing
3)Repolarizing
4)Hyperpolarzing
5)Refactory - Resting Potential
- Neurons possess electrical properties even when they are not receiving or transmitting messages. A difference in electrical charge between the inside (more negative) and outside of the neuron.
- Depolarization
- occurs when positive ions enter the neuron, making it more prone to firing an action potential (caused by excitatory messages)
- Repolarization
- Occurs when positive ions move out of the neuron restoring the membrane potential back to a negative value after the depolarization.
- Hyperpolarization
- caused by repolarization when negative ions enter the neuron, making it less prone to firing an action potential (caused by inhibitory messages)
- Threshold
- each neuron receives depolarizing and hyperpolarizing currents from many neurons. When the difference between these current exceeds a minimum intensity(threshold) the neuron fires an action potential. Difference=depolarization-hyperpolarization.
- Refractory Period
- after a neuron fires an action potential, it cannot fire again a short time
- Synapse
- a junction, the synaptic gap, between the axon terminal of one neuron and the dendrite of the next one.
- Neurotransmitters
- when an action potential reaches the end of the axon, it triggers vesicles in the axon terminal to release neurotransmitters (chemicals). Neurotransmitters bind to receptor sites on the receiving neuron and generate an action potential.
- Reuptake
- neurotransmitters in the synapse are reabsorbed into the sending neuron. Recycles neurotransmitters. Regulates normal level of neurotransmitter in the synapse.
- Major types of Neurotransmitters
-
-acetylcholine (ACh)
-Dopamine
-Endorphin
-Serotonin
-Gamma Amino-Butyric Acid (GABA) - Acetylcholine (ACh)
- Involved in triggering muscles to contract. Involved in learning and memory. A shortage of ACh has been associated with Alzheimer Disease.
- Serotonin
- Involved in modulating mood, anger, aggression, sleep, hunger, and arousal, as well as stimulating vomiting. July 4th, 2008- issue of science, decreased levels of serotonin have been associated with sudden infant death syndrome (SIDS)
- Gamma-Amino-Butyric Acid (GABA)
- Involved in regulating anxiety, decreased levels have been associated with anxiety disorders, epilepsy, schizophrenia, and addiction.
- Lock and Key Mechanism
- neurotransmitters bind to the receptors in a key-lock mechanism. A certain type of transmitter only works with certain receptor. Some drugs mimic action of transmitters (agonist and antagonist)
- Agonist
-
similar in structure to the neurotransmitter, mimicking its effects on the receiving neuron, eg producing an action.
ex. nicotine, mimics ACh, and morphine mimics endorphins by stimulating receptors invovled in mood and pain. - How do we study the Brain?
- clinical observation, activating brain electrically or chemically, and monitoring the brain.
- Clinical Obersavation
- Studying brain damage patients caused by neurological, psychiatric, diseases or accidents.
- Activating the Brain (Electrically or Chemically)
- Temporary brain manipulation (e.g used during brain surgery to reduce the seizures)
- Monitoring the Brain
- computerized tomography (CT) or computed Axial Tomography (CAT) scan. USes 2 computers to generate a 3D image from 2D xray pictures. Can reveal small tumors that cannot be seen on xray.
- Average Weight of Human Brain
- 3 pounds
- 3 major structurs of the brain
- hindbrain, midbrain, and forebrain.
- Hindbrain
-
acts as the "life support" e.g. breathing and heartbeat. no emotion/thought involved.
4 components, Reticular formation, pons and medula, and cerebellum. - reticular formation
- controls arousal
- pons and medula
- controls heartbeat and breathing
- cerebellum ("little brain")
- coordinates voluntary movements and balance
- Midbrain
- acts as a "relay system" for visual and auditory information. 3 major components, superior colliculus and inferios colliculus, substania nigra.
- Superior and Inferior Colliculus
- coordinates reactions to sensory information in the environment
- Forebrain
- carries out "higher" mental activity. 3 components, cerebral cortex, thalamus, limbic system.
- Limbic System
- (Hypothalamus, amygdala, and hippocampus) associated with memory, motivation, and emotion. hypothalamus=maintains activities like eating, drinking, body temp, control of emotions and sleep regulation
- structure of the cerebral cortex
- 4 lobes, frontal, parietal, temporal, and occipital
- frontal lobe
- motor control, speech production (brocas area), higher cognitive functions, inhibition or inappropriate behaviors.
- Phineas Gage
- foremane who had a rod go through his frontal lobe, personality changed.
- parietal lobe
- body sensation and perception of touch, includes motor cortex and sensory cortex
- occipital Lobe
- visual processing center (eg shape, color, light and orientation, ect.)
- The divided brain
- our brain is divided into 2 hemispheres which are lateralized
- Left hemisphere
- linguistic analysis (speech, reading, writing, math, and comprehension skills)
- Right hemisphere
- nonverbal analysis (responsible for emotional expression, artistic ability and visul/spacial information processing)
- Corpus Callosum
- transfers information across hemispheres
- Splitting the brain
- the brain is split by cuttin ghte corpus callusum
- split brain patients
- objects(apple) presented in the right visual field can be named, but objects (pencial) in the left visual field cannot. Moving head and eyes solves problem.
- Roger Sperry
- nobel prize winner for split brain research, documenting specialization of left and right hemispheres. "The great pleasure and feeling in my right brain is more than my left brain can find the words to tell you."
- sensation
- detect physical energy and convert into neural images
- perception
-
organize and interpret our sensations
- signal detection
- detection of weak signal in noise is crucial to performance of many tasks
- signal detection theory
- predicts how and when we detect presence of signal in noise. (depends on person level of experience, expectations, motivations, level of fatigue)
- 2 variables in signal detection theory matrix
- observer decides whether the signal is there, reality if it is there or not
- wavelengths humans are sensitive to
- 381-760 nanometers
- parts of retina
-
3 layers-
ganglion cell, bipolar cell, and rods and cones - rods
- little spacial detail, operate in love life. max response is 500 nm, blueish
- cones
- detect detail, operate in high light, longer than 500 nm, respond to color
- Purkinje shift
-
during day= cone system
during night= rod system - fovia
- only contains cones, no rods
- blind spot
- light enters-back of eye-rods and cones-bipolar cell-ganglian cell-optic nerve
- trichromatic theory
- blue, green and red only. blue is short, green is medium and red is long. colors are sensed by comparing amount og activation coming from each type
- subtraction of colors
- if 3 primary colors(pigments) are mixed subtraction of all wavelength occurs and the color black results.
- addition of colors
- if 3 primary colors (light) are mixed, wavelengths are added and the color white results. ex) tv create all visible colors by additively mixing blue, green and red.
- color blindness
- genetic disorder in which people are blind to some colors, according to trichromatic theory, results from having the wrong kind of photopigment in the cones
- opponent process theory
- process 4 primary colors combined in pairs (red-green, blue-yellow, and white-black). receptors respond positively to one color and negatively to the complimentary color.
- sensation blend
- bottom up theory testing, controlled by physical message delivered to the senses
- gesalt principles
- organize visual info, perception differs from reality, "the whole is more than the sum of the parts"
- proximity
- elements close together in space tend to be grouped together
- similarity
- similar shapes, colors, sizes, orientation, tend to be grouped together
- continuity
- objects arranged in a straight or curved line tend to be grouped together
- closure
- open curves tend to be perceived as a complete.
- common fate
- elements moving in a common speed tend to be grouped together
- common region and connectedness
- stove oven design
- motion perception
- images are always movig around on the retina regardless of whether the pbjects are still or not
- induced motion
- light appears to move in the opposite direction of the frame
- autokinetic motion
- occurs when a stable light is viewed in a completely dark room and appears to move
- movement aftereffect
- if moving striped are viewed prior to viewing s still object, object movesin opposite direction. hypnotize yourself youtube
- oculomotor
- accomodation and convergence, provide depth cues through feedback from the muscles that control the lense and the convergence angle
- binocular
- the retinas in our eyes receive different images (retinal disparity)
- monocular
- requires input from only one eye, called pictorial cues.
- motion parallax
- as we move, stable objects appear to move relative to us.