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Psych 402 Biological Psychology Chapter 6 and 7
Terms in this set (18)
1. Be able to describe the parts of the eye and its connections to the brain.
Light enters through the pupil and is focused by the lens and cornea and projected onto the retina which is ligned with rods and cones. Receptor - bipolar cells - ganglion cells - optic nerve (blind spot) - brain.
2. Understand the process by which three types of cones, and the neurons they connect with, can produce a rich spectrum of perceived color.
Young Helmholtz trichromatic theory -Short, medium, and long, wavelengths of light are picked up by their respective cones which interpret them as blue, green, and red respectively. Overlap of wavelengths produces varying colours.
Opponent process theory says we perceive color in terms of opposites. Red to green, yellow to blue, white to black.
The rods pass the signal onto the bipolar cell - ganglion cell - optic nerve. Horizontal cell is involved in inhibition.
3. Understand the trade-off between acuity for detail and sensitivity to dim light.
Sensitivity to detail in bright conditions and sensitivity in low light demands two different types of visual mechanisms, and hence a tradeoff between them. This tradeoff is based on:
1. Two types of photoreceptors: rods and cones
2. A difference in the retinal distribution of the two receptor types
3. Variation in photoreceptor density across the retina: cones densely packed in the central retina (around the fovea), rod density greatest about 18 - 20° from the fovea
4. Rods and cones adjust for sensitivity differently
5. Rods and cones differ in the extent of their convergence on retinal neurons
1. Understand the concept of receptive fields and how they change from the retina to the various areas of the visual cortex.
Receptive field in a receptor is the area of light that strikes it. In other cells it's the are of visual space excited or inhibited. Receptive fields grow larger as they progress through the various cells - rod/come - bipolar cell - ganglion cell - visual cortex. They include excitatory and inhibitory receptive fields.
2. Understand the inputs to the dorsal and ventral streams of cortical processing and what each pathway analyzes.
Ventral is the what stream - processes object and visual identification. Foveal and parafoveal inputs.
Dorsal is where stream - processes spatial location relative to the viewer. Acrross the retina inputs.
Both sent out ffrom the visual cortex V1 or lateral geniculate nucleous.
Ganglion cells fall into :
Parvocellular - Small bodies small receptive fields. Found near fovea. Good details and color as they are small and located near the fovea where many cones reside.
Magnocellular - Larger bodies, larger fields. Distributed evenly throughout retina. Movement and large patterns but not detail and color.
Koniocellular - Small bodies but throughout retina.
3. Know the contributions of areas V1, V2, and inferior temporal cortex to shape perception.
V1 detects spatial frequencies. It sends information to the secondary visual cortex V2, which processes it and sends it on to other areas. V1 and V2 are reciprocal with information. V2 sends on to ventral stream (temporal cortex) and dorsal stream (parietal cortex).
Inferior temporal cortex responds to what is perceived, not what the shape actually is. The inferior temporal cortex learns what the object is and can recognize it at a different position, with a different size or angle.
4. Be able to describe the brain areas that process color and motion.
Area V4 processes colour perception - the ability to recognize a colour despite a change in lighting or background or nearby objects.
MT: Middle temporal cortex or V5. Responds to acceleration, deceleration, absolute speed.
MST: Medial superior temporal cortex. Responds to more complex, expansion, contraction, rotation.
Receive stimulus from the magnocellular path which perceives patterns and movement over large visual areas.
1. Be able to describe the physical structures of the ear and their contributions to hearing.
Outer Ear - Pinna alters the reflection of sound waves which helps to locate sound. External canal.
Middle Ear - Tympanic membrane. Vibrates at the frequency of the sound waves striking it. Tympanic membrane connects to the hammer, anvil, and stirrup which transmits and amplifies the vibrations/pressure to the oval window.
Inner Ear - The increased force Is needed because of the viscous fluid on the inside of the oval window. Inside the inner ear lies the cochlea and vestibules within. Vibration of the oval window causes the viscous fluid to move in the vestibules where hair cells connected to the auditory nerve are located. Movement of these cells stimulates the nerve and is perceived as hearing.
2. Understand the mechanisms of pitch perception and sound localization
Different frequencies register with different receptors along the basal membrane with the highest frequencies being closest to the oval window 20khz. The basal membrane widens and becomes less stiff as it progresses.
Place theory - states that perception of sound depends on where each component of frequency produces vibration along the basal membrane.
Frequency theory - states that the basilar membrane vibrates in synchrony with a sound, causing auditory nerve axons to produce action potentials at the same frequency. Downfall is the refractory period 1/1000 sec of neurons would limit the frequency to 1000hz.
Current theory and volley principle - up to 100hz the basal membrane vibrates with the frequency of the sound. At higher frequencies the neurons may fire every second, third, etc. as the action potentials of the nerve are phase locked. A sum of other auditory neurons phase locked at different points of the frequency come together to account for the whole frequency.
3. Know the types of hearing loss and the conditions that can cause them.
Conductive deafness or Middle ear deafness - diseases, infections, tumor growth
Nerve deafness can be inherited or developed. - results from damage to cochlea, hair cells, or auditory nerve. Can occur in any degree. Can be inherited if the mother is exposed to rubella, syphilis. Inadequate O2 during birth, deficient thyroid, MS, loud noises.
1. Understand the roles of the otoliths and semicircular canals in vestibular sensation.
Otoliths are calcium carbonate particles that lie next to hair cells, when the head tilts the otoliths press against the hair cells and excite them.
Semicircular canals are oriented in perpendicular planes filled with a jelly like substance and hair receptors. Acceleration of the head at any angle causes the jelly to stimulate the hair cell.
Action potentials initiated by the vestibular system travel through part of cranial nerve VIII to the brainstem and cerebellum.
Modified touch receptors
3. Be able to describe the cortical processing of somatosensory information.
Receptors from the head enter the CNS through the cranial nerves. Below the head the 31 spinal nerves. Each spinal nerve has sensory and motor component.
Somatosensory information converges in the parietal lobe of the cerebral cortex where it is processed to provide a cohesive perception of your body and your physical environment.
4. Understand the roles of the various neurotransmitters in the production and the alleviation of pain and itch sensations.
In the spinal cord pain axons release GLUTAMATE for mild pain and GLUTAMATE plus SUBSTANCE P for stronger pain.
Opiate receptors block substance p. Endorphins stimulate opiate receptors with endogenous morphines.
1. Understand the concepts of the labeled-line and across-fiber pattern principles and how they apply to each of the senses.
Labeled-line pattern - Requires each receptor responds to a limited range of stimuli and the meaning depends on which neuron Is active.
Across fiber pattern - Each receptor responds to a wide range of stimuli and a given response by a single axon means little without the context of what other axons are doing.
Most perceptions require a response across several axons.
2. Understand the mechanisms of the taste receptors and be able to describe the pathways of taste coding in the brain.
Salt receptor simply allows sodium to enter the cell.
The remaining receptors stimulate a secondary messenger via G protein.
Signals from the anterior tongue travel along the chorda tympani of the 7th cranial nerve.
Signals from the posterior tongue travel along the 9th and 10th cranial nerves.
Signals project to the NTS of the medulla. It branches out from the for interpretation.
3. Be able to describe the operation and numbers of olfactory receptors, and the implications of the numbers of receptors for coding olfactory information.
Estimated to have several hundred receptors. Olfactory receptors proteins transverse the cell membrane 7 times. Triggering of a receptor causes a g protein secondary messenger response. Sends impulse to olfactory bulb.
Each chemical stimulates several receptor but rhe strongest response inhibits other receptors, similar to lateral inhibition. Result is a given chemical produces a major response in 1 or 2 receptors and a minor response in some others.
Having many receptors allows a single receptor to identify only one or two chemicals precisely. This is required to process air born particles that are arranged in no particular order.
4. Understand the types of stimuli that the vomeronasal organ responds to and differences between the vomeronasal and olfactory systems.
Pheromones. Less important in humans. Vomeronasal organ located near but separate from the olfactory. Olfactory stimulation sensitizes but vomeronasal stimulation continues strongly.
5. Be able to describe synesthesia and its possible anatomical basis.
Experience of one sense is perceived as that sense plus another sense.
Beef tastes dark blue. Axons from one cortical area branch into another cortical area
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