Definitions Flashcards
chronic traumatic encephalopathy (CTE)
form of progressive brain damage that has been linked to repeated concussions. associated with an array of cognitive and emotional deficits in affected individuals, including an ability to concentrate, memory loss, irritability, and depression, usually beginning within a decade and worsening with time.
neurons
cells in the nervous system that communicate with one another to perform information-processing tasks. composed of three basic parts: the cell body, dendrites, and the axon.
cell body
also called the soma; coordinates the info-processing tasks and keeps the cell alive. functions such as protein synthesis, energy-production, and metabolism take place here.
nucleus
contained in the cell body; houses chromosomes that contain DNA.
cell membrane
surrounds the cell body and allows some molecules to flow into and out of the cell.
two types of specialized extensions of the cell member that allow neurons to communicate
dendrites and axon.
dendrites
receive info from other neurons and relay it to the cell body. comes from the greek word for “tree”
axon
carries info to other neurons, muscles, or glands, can be very long, even stretching up to a meter from the base of the spinal cord to the big toe.
synapse
junction or region between the axon of one neuron and the dendrites or cell body of another. transmission of info across the synapse is fundamental to communication between neurons, a process that allows us to think, feel, and behave.
myelin sheath
covers the axon; an insulating layer of fatty material.
glial cells
composes the myelin sheath; support cells found in the nervous system. named for the greek word “glue.” some digest parts of dead neurons, others provide physical and nutritional support for neurons, and other form myelin to help the axon carry important info more efficiently.
axons insulated with myelin
can more effectively transmit signals to other neurons, organ, or muscles.
dymyelinating diseases
such as multiple sclerosis, the myelin sheath deteriorates, slowing the transmission of info from one neuron to another. leads to problems including loss of feeling in the limbs, partial blindness, and difficulties in coordinated movement and cognition.
sensory neurons
(somatic side) receive info from the external world thru sensory receptors and conveys info to the brain via from the axons that carry the Aps back to the spinal cord. specialized ending on dendrites that receive signals for light, sound, touch, taste, and smell.
motor neurons
(somatic side) carry signals from the brain to the spinal cord to the muscles to produce movement. long axons that can stretch to muscles in our extremities from spinal cord.
interneurons
(inside cns, skull, vertebrate) connect sensory, motor, or other interneurons. some carry info from the nervous system to motor neurons and others perform a variety of info-processing functions within the nervous system. connects one area of brain w/ another.
conduction
info travels inside a neuron via an electrical signal that travels from the dendrite to the cell body to the axon.
transmission
signal has to be passed from one neuron to another, usually via chemical messengers traveling across the synapse.
ions
small electrically charged molecules. flow across the neuron’s cell membrane creates the conduction of an electrical signal within the neuron.
resting potential
No communication, negative char within the neuron . difference in electrical charge between the inside and the outside of a neuron’s cell membrane. differences arise from the concentrations of ions. a high concentration of a positively charged ion, potassium (K+), as well as negatively charged protein ions (A-), inside the neuron’s cell membrane. a high concentration of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl -) outside the neuron’s cell membrane.
resting state
the channels that allow the flow of K+ molecules across the cell membrane are open, while the channels that allow the flow of Na+ and other ions are generally closed.
charge of neuron at rest
due to the higher concentration of K+ molecules inside the neuron, some K+ molecules move outside through open channels, leaving the inside of the neuron with a charge of -70 millivolts relative to the outside.
Hodgkin and Huxley
could produce a signal by stimulating the axon with a brief electric shock, which resulted in the conduction of an electric impulse down the length of the axon.
action potential
communication; brief positive electrical charge that travels down as axon as charged ions move in and out of the axon’s membrane to the synapse.
threshold
the level at which an electrical shock reaches to cause action potential to occur. all or none firing.
all or none
electric stimulation below the threshold fails to produce an action potential, whereas electric stimulation at or above the threshold always produces the action potential, which always occurs with exactly the same chars and at the same magnitude regardless of whether the stimulus is at or above the threshold. all or none firing.
during an action potential
the K+ channels briefly shut down and the channels that allow for the flow of positively charged sodium ions (Na+) are opened. Na+ flow inside, increasing the positive charge inside the axon relative to the outside. +40 millivolts.
after action potential
after max is reached, the membrane channels return to their original state and K+ flows out until the axon returns to its resting potential. leaves extra Na+ ions inside and extra K+ outside.
refractory period
ions are imbalanced; time following an action potential during which a new action potential cannot be initiated. imbalance is reversed by a chemical “pump” in the cell membrane that moves Na+ outside the axon and moves K+ inside the axon.
how action potentials spread
when an AT is generated at the beginning of the axon, it spreads a short distance, which generates an AT at a nearby location on an axon, thus conducting charge down the length of the axon.
nodes of Ranvier
break points between myelin clumps covering axons. named after Louis-Antoine Ranvier, who discovered them.
saltatory conduction
an electric current that passes down the length of a myelinated axon, the charge jumps from node to node rather than transverse the entire axon. helps speed the flow of info.
terminal buttons
knob-like structures that branch out from an axon. filled with tiny vesicles.
vesicles
found within terminal buttons; contains neurotransmitters.
receptors
parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electrical signal.
presynaptic neuron
Sending neuron that the action potential travels down the length of its axon to the terminal buttons, where it stimulates the release of neurotransmitters from the vesicles into the synapse.
Postsynaptic neuron
Receiving neuron where neurotransmitters that float across the synapse bind to receptor sites on nearby dendrites of these neurons
Synaptic transmission
New electrical signal initiated in the postsynaptic neuron, which at generate an action potential in that neuron. Allows neurons to communicate with one another.
neurotransmitter binding
Some will only bind to specific receptor sites on dendrites.
Neurotransmitters leave the synapse through three processes
Reuptake, enzyme deactivation, and auto receptors
Reuptake (synaptic communication terminated)
Neurotransmitters can be absorbed by the terminal buttons of the presynaptic neuron’s axon.
Enzyme deactivation (synaptic communication terminated)
Neurotransmitters can be destroyed by enzymes in the synapse.
Autoreceptors
Neurotransmitters can bind to these on the presynaptic neuron. Detect how much of a neurotransmitter has been released into a synapse and signal the presynaptic neuron to stop releasing the neurotransmitter when an excess is present.
Acetylcholine (ACh)
Neurotransmitter involved in a number of functions, including voluntary motor control. Found in neurons of the brain and in the synapses where axons connect to muscles and body organs, such as the heart. Contributes to the regulation of attention, learning, sleeping, dreaming, and memory. Alzheimer’s disease is associated with the deterioration of this.
Dopamine
Neurotransmitter that regulates motor, behavior, motivation, pleasure/reward, and emotional arousal. Plays a role in drug additions. High levels linked to schizophrenia and low levels linked to Parkinson’s disease.
Glutamate
Major excitatory neurotransmitter in the brain, meaning that it enhances the transmission of info between neurons.
GABA (gamma-aminobutyric acid)
Primary inhibitory neurotransmitter in the brain. Tends to stop the firing of neurons. Helps fall asleep, prevents seizures/getting too excited.
Overactive neurons
Caused by too much glutamate or too little GABA. causes seizures.
Norepinephrine
Involved in vigilance, or a heightened awareness of dangers in the environment. Low levels implicate mood disorders.
Serotonin
Involved in the regulation of sleep and wakefulness, eating, and aggressive behavior. Low levels implicate mood disorders.
Endorphins
Chemicals that act within the pain pathways and emotion centers of the brain. Help full the experience of pain and elevate moods.
Agonists
Drugs that increase the action of a neurotransmitter.
Antagonists
Drugs that block the function of a neurotransmitter.
Parkinson’s disease
Movement disorder characterized by tremors and difficulty initiating movement and caused by the loss of neurons that use the neurotransmitter dopamine.
How dopamine is creates
Created in neurons by a modification of a molecule called L-dopa. Ingesting L-dopa will spur the surviving neurons to produce more dopamine.
Amphetamine
Drug that stimulates the release of norepinephrine and dopamine. Both amphetamine and cocaine prevent the reuptake of these releases and this floods the synapse with these neurotransmitters, resulting in increased activation of the receptors. Increase results in euphoria, wakefulness, and a burst of energy. Norepinephrine also increases heart rate dangerously.
Nerves
Bundles of axons and the glial cells that support them.
Nervous system
An interacting network of neurons that conveys electrochemical info throughout the body.
Central nervous system (CNS)
Composed of the brain and the spinal cord. Receives sensory info from the external world, processed, and coordinates this info and sends commands to the skeletal and muscular systems for action.
Peripheral nervous system (PNS)
Connects the CNS to the body’s organs and muscles. Subdivisions include the autonomic and somatic nervous systems.
Somatic nervous system
Set of nerves that conveys info between voluntary muscles and gathers sensory input (pain, heat, cold, pressure); sent back to the CNS. Conscious control and use it to perceive, think, and coordinate behavior.
Autonomic nervous system (ANS)
Set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, and glands. Largely outside conscious control. Divided into sympathetic and parasympathetic nervous systems.
(autonomic ->) sympathetic nervous system
(fight or flight) revs up organs you need, less energy to things you don’t need. Set of nerves they prepares the body for action in challenging or threatening situations.
(autonomic ->) parasympathetic nervous system
(resting and digesting) interested in conserving energy and only using what you need. Helps the body return to normal resting state.
Brain
Supports the most complex perceptual, motor, emotional, and cognitive functions of the nervous system.
Spinal cord
Branches down from the brain to relay commands to the body.
Spinal reflexes
Simple pathways in the nervous system that rapidly generate muscle contractions.
Injuries on spinal cord
The higher up, the more damaging the effects are.
Hindbrain =
Area of the brain that coordinates info coming into and out of the spinal cord. Controls the most basic functions of life: respiration, alertness, and motor skills. Structure include the medulla, the reticular formation, the cerebellum, and the pons.
Medulla (hindbrain: Myelencephalon)
Extension of the spinal cord into the skull that coordinates heart rate, circulation, and respiration.
Reticular formation (midbrain: Mesencephalon)
extends from hind brain to part of forebrian. nonrepreprhine comes from here. Small cluster of neurons; regulates sleep, wakefulness, and levels of arousal. Cat experiment: stimulation kept the cat alert, severing the connection created a permanent coma.
Cerebellum (hindbrain: Metencephalon)
Large structure of the hindbrain they controls fine motor skills. Contributed to the fine-tuning of behavior: smoothing our actions to allow their graceful execution rather than initiating the actions.
Pons (hindbrain: Metencephalon)
Structure that relays info from the cerebellum to the rest of the brain. Essentially acts as a relay station/bridge between the cerebellum and other structures in the brain.
Midbrain
Relatively small and contains the tectum and tegmentum, which help orient an organism in the environment and guide movement towards/away from stimuli.
Forebrain
Highest level of the brain and controls complex cognitive, emotional, sensory, and motor functions. Divided into the subcortial structures and the cerebral cortex.
Subcortial structures
Areas of the forebrain housed under the cerebral cortex near the center of the brain they include the thalamus, hypothalamus, pituitary gland, hippocampus, amygdala, and basal ganglia, and these structures play an important role in relaying info throughout the brain as well as performing specific tasks that allow us to think, feel, and behave as humans.
Thalamus (Forebrain: Diencephalon)
Delays and filters info from the senses and transmits the info to the cerebral cortex. Receives input from all major senses except smell, and acts as a computer server in a networked system, tasking in multiple inputs and relaying them to a variety of locations. Filters sensory info, giving more weight to some inputs and less to others. Closes the pathways of incoming sensations during sleep, proving a valuable function in not allowing info to pass the rest of the brain.
Hypothalamus (Forebrain: Diencephalon)
Located below the thalamus; regulates the body temp, hunger, thirst, and sexual behavior. controls endocrine system; sends horomones.
Pituitary gland
The master gland of the body’s hormone producing system, which releases hormones that direct the functions of many other glands in the body. Hypothalamus sends hormone signals to the pituitary gland, which in turns sends the signals to other glands that control stress, digestive activities, and reproductive processes.
Hippocampus (limbic system)
Critical for crating new memories and integrating them into a network of knowledge so that they can be stored indefinitely in other parts of the cerebral cortex. Damage is limited to the disruption of everyday memory for facts and events that we can bring into consciousness; memory of learned habitual routines or emotional reactions remain intact.
Amygdala (limbic system)
Located at the tip of each horn of the hippocampus, plays a critical role in many emotional processes, particularly the formation of emotional memories. In emotionally arousing situations, the amygdala stimulates the hippocampus to remember many details surrounding the situation.
Basal ganglia
Set of subcortial structures that direct intentional movements. Receives input from the cerebral cortex and sends outputs to the motor centers in the brain stem.
Striatum
Part of the basal ganglia; involved in the control of posture and movement.
Parkinson’s disease
Uncontrollable shaking and sudden jerks, unable to initiate a sequence of movements to achieve a specific goal. Dopamine producing neurons in the tegmentum have become damaged and the undersupply affects the striatum.
Cerebral cortex (forebrain: telencephalon)
The outermost area of the brain, visible to the naked eye, and divided into two hemispheres. Highest level of the brain and responsible for the most complex aspects of perception, emotion, movement, and thought.
1) organization across the hemispheres
Divides the cortex into left and right hemispheres. Each hemisphere controls the functions of the opposite of the body. Connected by bundles of axons that make communication between parallel areas of the cortex in each half possible.
Contralateral control
Right cerebral hemisphere perceives stimuli from and controls movements on the left side of the body. Vice versa.
Corpus callosum
Connects large areas of the cerebral cortex on each side of the brain and supports communication of info across the hemispheres. Largest of the bundles of axons that make communication possible.
2) organization within hemispheres
Second level of organization; distinguishes the functions of the different regions within each hemisphere of the brain. Each hemisphere of the cerebral cortex is divided into four lobes: the occipital lobe, the parietal lobe, the temporal lobe, and the frontal lobe.
Occipital lobe
Located at the back of the cerebral cortex; processes visual info. Sensory receptors in the eyes send info to the thalamus, which in turn sends info to the primary areas of the lobe, where simple features of the stimulus are extracted, such as location and orientation of the object’s edges. Processes further, leading to comprehension. Damage = blindness. Contains visual cortex (oragnizes and processes visual stimuli such as color, movement, depth)
Parietal lobe
Located in the front of the occipital lobe; processes info about touch. Contains somatosensory cortex (organizes and perceives the touch signals)
Somatosensory cortex
Within the parietal lobe; a strip of brain tissue running from the top of the brain down to the sides. Represents the skin areas on the contra lateral surface of the body. Each part of the cortex maps onto a particular area of the body. More sensitive = larger part of the somatosensory cortex is devoted to it. Homunculus illustration.
Motor cortex
In front of the somatosensory cortex, in the frontal lobe. Different parts correspond to different body parts. Initiates voluntary movements and sends messages to the basal ganglia, cerebellum, and spinal cord.
Temporal lobe
Located on the lower side of each hemisphere; responsible for hearing and language. Contains auditory cortex (receives incoming auditory signals from thalamus, sorts into recognizable pattern)
Primary auditory cortex
In the temporal, analogous to the somatosensory cortex in the parietal lobe and the primary visual areas of the occipital lobe. It receives sensory info from the ears based on frequencies of sounds. Secondary areas of the temporal then process the info into meaningful units such as speech and words. Houses the visual association areas that interpret the meaning of visual stimuli and help us recognize common objects in the environment.
Frontal lobe
(cerebral cortex) Specialized areas for movement, abstract thinking, planning, memory, and judgement. Contains the motor cortex (comes up w/ plan to do something) and prefront cortex (stores social norms/rules). Other areas coordinate thought processes that help us manipulate info and retrieve memories.
3) organization within specific lobes
Hierarchy of processing stages from primary areas that handle fine details of info all the way up to association areas.
Association areas
Composed of neurons that help provide sense and meaning to info registered in the cortex.
Mirror neurons
Active when an animal performs a behavior, such as reaching for or manipulating an object, and they are also activated when another animal observed the first animal as it performs the same behavior. Found in the frontal lobe near the motor cortex and in the parietal lobe.
Neurons in association areas
Usually less specialized and more flexible than neurons in the primary areas. Can be shaped by learning and experience to do their job more effectively. Allows for brain plasticity.
Sensory cortices
Not fixed and can adapt to changes in sensory inputs.
Functions in the brain
Functions assigned to certain areas of the brain may be capable of being reassigned to other areas of the brain to accommodate changing input from the environment.
Exercise
Studies in rats and other animals indicate that exercise can increase the number of synapses and even promote the development of new neurons in the hippocampus.
Cilia
Help the Protozoa toward the food source.
First neurons
Appeared in simple invertebrates such as jellyfish.
First CNS
Appeared in flatworms. Collections of neurons in the head including sensory neurons for vision and tease and motor neurons that control feeding behavior.
In all vertebrates
The CNS is organized into a hierarchy: the lower levels of the brain and spinal cord execute simpler functions, while the higher levels the nervous system performs more complex functions.
In lower vertebrate species
The forebrain consists only of small clusters of neurons at the end of the neural tube.
In higher vertebrates
The forebrain is much larger and it evolves in two different patterns. Reptiles and birds have almost no cerebral cortex. Mammals have a highly developed cerebral cortex, which develops multiple areas that serve a broad range of higher mental functions uniquely human abilities include self awareness, sophisticated language, abstract reasoning, and imaging.
Gene
Major unit of hereditary transmission. Sections on a strand of DNA that are organized into large threads called chromosomes.
Chromosomes
Strands of DNA wound around each other in a double helix. Comes in pairs, one from mother and father. Humans have 23 pairs.
Degree of relatedness
Probability of sharing genes.
Monozygotic twins (identical twins)
Most genetically related people; develop from splitting a single fertilized egg and therefore share 100% of their DNA.
Dizygotic twins (fraternal twins)
Develop from two separate fertilized eggs and share 50% of their genes. The same as any two siblings born separately.
Epigentics
Environmental influences that determine whether or not genes are expressed, or the degree to which they are expressed, without altering the basic DNA sequences that constitute the genes themselves. Known to play a role in functions including learning and memory and also responses to stress.
3 days to understand how the brain affects behavior
Studying people with brain damage; studying the brain’s electrical activity; and using brain imaging to study brain structure and watch the brain in action.
Research in neuroscience
Correlates the loss of specific perceptual, motor, emotional, or cognitive functions with specific areas of brain damage.
Corpus callosum
Thick band of nerve fibers that allows the two hemispheres to communicate.
Split brain procedure
To alleviate the severity of the seizures, surgeons can sever the corpus callosum. A seizure that starts in one hemisphere cannot cross to the other side. In a split brain, info entering on hemisphere stays there. Objects (apple) presented in right field can be named. Objects (pencil) presented in the left visual field cannot.
Electroencephalograph (EEG)
Device used to record electrical activity in the brain. Electrodes are placed on the outside of the head and this provides a visual record of the underlying electrical activity. Researchers can determine the amount of brain activity during different states of consciousness. Can also be used to examine the brains electrical activity when awake individuals engage in a variety of psychological functions, such as perceiving, learning, and remembering.
Feature detectors
Neurons in the visual cortex; selectively respond to certain aspects of a visual image. Identify basic dimensions of a stimulus and these dimensions are then combined to allow recognition and perception of a stimulus.
Neuroimaging techniques
Used advanced technology to create images of the living healthy brain.
Structural brain imaging
Provides info about the basic structures of the brain and allows clinicians or researchers to see abnormalities in brain structure.
Functional brain imaging
Provides info about the activity of the brain when people perform various kinds of cognitive and motor tasks.
Computerized axial tomography (CT) scan
A scanner rotates a device around a person’a head and takes a series of X-Ray photographs from different angles. Computer programs then combine these images to provide views from any angle. Show different densities of tissue in the brain. White = high density skill, gray = cortex, dark = least dense fissures and ventricles in the brain.
Magnetic resonance imaging (MRI)
Uses a strong magnetic field to line up the nuclei of specific molecules in the brain tissue. Brief and powerful pulses of radio waves cause the nuclei to rotate out of alignment. When a pulse ends, the nuclei snap back in line with the magnetic field and give off a small amount of energy in the process. Different molecules have unique energy signatures when they snap back in line with the magnetic field, so these signatures can be used to reveal brain structure with different molecular composition. Soft tissues have a better resolution.
Diffusion tensor imaging (DTI)
Type of MRI that is used to visual matter pathways, which are fiber bundles that connect both nearby and distant brain regions to one another. Measures the rate and direction of diffusion or movement of water molecules along white matter pathways. Can use measures based on the rate and direction of diffusion to assess the integrity of a pathway, useful for neurological and psychological disorders.
Human Connectome Project
Collaborative effort funded by the national institutes of health in 2009. Aims to provide a complete map of the connectivity of neural pathways in the brain: the human Connectome. DTI plays central role.
Positron emission tomography (PET)
Harmless radioactive substance is injected into a persons bloodstream. Brain is scanned by radiation detectors ass the person performs perceptual or cognitive tasks. Areas activated during these tasks demand more energy and greater blood flow, resulting in a higher amount of radioactivity in that region. Produce computerized images of that area.
Functional magnetic resonance imaging (fMRI)
Detects the difference between oxygenated hemoglobin and deoxygenated hemoglobin when exposed to magnetic pulses.
Hemoglobin
Carries oxygen to tissues.
Advantages of fMRI over PET
1) fMRI does not require exposure to radioactive substances 2) fMRI can localize changes to brain activity across briefer periods than PET, which makes it more useful for analyzing psychological processes that occur extremely quickly.
Fusiform gyrus
Region located near the border of the temporal and occipital lobes. When damaged, people experience problems recognizing faces.
Resting state functional connectivity
Rest while fMRI measurements are made. Measures the extent to which spontaneous activity in different brain regions is correlated over time.
Networks
Sets of brain regions that are closely connected to one another.
Default network
Identified by functional connectivity; group of interconnected regions in the frontal, temporal, and parietal lobes that is involved in internally focused cognitive activities, such as remembering past events, imaging future events, daydreaming.
Transcranial magnetic stimulation (TMS)
Delivers magnetic pulse that passes through the skill and deactivates neurons in the cerebral cortex for a short period. Can direct TMS impulses to particular brain regions and then measure temporary changes in vision, thinking, remembering, speaking, or feeling.
Magnetic stimulation of the visual cortex
Temporarily impairs a person’s ability to detect the motion of an object without impairing the ability to recognize the object. Activity in the visual cortex causes motion perception.
Combining TMS with fMRI
Allows them to localize precisely in the brain TMS is having its effect.
sensory branding
notion that the sight and sound of exciting things will become associated with what might be an otherwise drab product. enlists sound, smell, taste, and touch as well as vision.
sensation
simple stimulation of a sense organ. basic registration of light, sound, pressure, odor, or taste as parts of your body interact with the physical world. takes place in the CNS.
perception
Occurs in cerebral cortex. organization, identification, and interpretation of a sensation in order to form a mental representation. takes place in the brain.
transduction
when many sensors in the body convert physical signals from the environment into encoded neural signals sent to the CNS.
psychophysics
developed by Gustar Fechner; methods that measure the strength of a stimulus and the observer’s sensitivity to that stimulus.
absolute threshold
minimal intensity needed to just barely detect a stimulus in 50% of the trails.
changes vs onset/offset
human perceptual system is better at detecting changes in stimulation than the simple onset or offset of stimulation.
just noticeable difference (JND)
minimal change in a stimulus that can just barely be detected. not a fixed quantity, rather it is roughly proportional to the intensity of the stimulus.
Weber’s law
the JND of stimulus is a constant proportion despite variations in intensity.
noise
the other stimuli coming from the internal and external environment.
signal detection theory
the response to a stimulus depends both on a person’s sensitivity to the stimulus in the presence of noise and on a person’s decision criterion
sensory adaptation
sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions.
sensory system responses
respond more strongly to changes in stimulation than to constant stimulation.
visual acuity
the ability to see fine detail.
wavelengths
the height and distance in between the peaks of light waves. hue.
length
determines the hue of a lightwave.
amplitude
the height of the peaks; determines the brightness.
purity
number of distinct wavelengths that make up the light; determines saturation.
cornea
clear, smooth outer tissue of the eye. where light passes through the eye first.
pupil
hole in the colored part of the eye
iris
translucent muscle that controls the size of the pupil and the amount of light that can enter the eye. pigmented circular muscle.
behind the iris
muscles inside the eye control the shape of the lens to bend the light and focus it onto the retina.
retina
light sensitive tissue lining the back of the eye.
lens: flat vs round
flatter for objects that are far away, rounder for nearby objects
accommodation
process by which the eye maintains a clear image on the retina.
nearsightedness (myopia)
eyeball is too long, so images are focused in front of the retina.
farsightedness (hyperopia)
eyeball is too short, so images are focused behind the retina.
photoreceptor cells
contain light sensitive pigments that transduce light into neural impulses. cones and rods.
cones
detect color, operate under normal daylight conditions, and allow us to focus on fine detail. Each retina contains only 6 mill cones, which are densely packed in the fovea and sparsely distributed over the rest of the retina. Affects visual acuity, which explains why objects in peripheral vision aren’t as clear
rods
become active under low light conditions for night vision. 120 million rods are distributed around each retina.
fovea
an area of the retina where vision is the clearest and there are no rods. decreases the sharpness of vision in reduced light because of the absence of rods.
Bipolar cells
Collect neural signals from the rods and cones and transmit them to the retinal ganglion cells (RGCs).
Retinal ganglion cells (RGCs)
Organize the signals from photoreceptors and sends them to the brain through the optic nerve.
Optic nerve
Formed by bundled RGC axons; leaves the eye through a hole in the retina. This holes creates a blind spot.
Blind spot
Location in visual field that produces no sensation on the retina.
Visible spectrum
Shortest wavelengths = deep purple. Then blue, green, yellow, orange. Longest = red.
3 types of cones
Red, green, blue.
Color deficiency
When one, two, or three cones are missing. Sex linked, affecting men more often. Referred to as color blindness.
Color afterimage
Results from staring too long at one color which fatigues the cones that respond to that color.
Axons in the optic nerve
Half of the axons in the optic nerve that leave each eye comes from the RGCs that code info in the right visual field and half from the left. These two nerve bundles link to the left and right hemispheres of the brain. The optic nerve travels from each eye to the thalamus. The visual signal then travels to area VI
Area VI
Part of the occipital lobe that contains the primary visual cortex.
Perceiving shape
Depends on the location and orientation of the objects edges.
Neurons in area VI
Each tuned to respond to edges oriented at each position in the visual field.
Visual streams
Project from the occipital cortex to visual areas in other parts of the brain.
Ventral (below) stream
Travels across the occipital lobes to the temporal lobe and includes brain areas that represent an object’s shape and identity.
Dorsal (above) stream
Travels up from the occipital lobe to the parietal lobes (including some of the middle and upper levels of the temporal lobes), connecting with brain areas they identify the location of an object as well as its motion. Crucial for guiding movements, such as ailing, reaching, or tracking with the eyes.
neurotransmitters
chemical messengers released when AP reaches the terminal button, carry message across the synapse, fit into receptors (lock and key) on the receiving neuron (inhibitory, excitatory)
why study the nervous system?
Controls all thoughts and behavior, shaped by our experiences/behavior (plasticity)
Neuronal structure
- Cell body (soma), dendrites, axons –myelin – terminal buttons – vesicles (storage container of neurotransmitters) – transporter molecules
Visual form agnosia
Inability to recognize objects by sight.
Brain damage to parietal lobe (part of dorsal)
Have difficulty using vision to guide their reaching and grasping movements. Ventral streams are intact, so they recognize what objects are.
Binding problem
How feature are linked together so that we see unified objects in our visual world rather than free floating or miscombined features. Makes use of feature info processed by structures within the ventral visual stream. Also depends on the parietal lobe in the dorsal stream.
Illusory conjunction
A perceptual mistake where features from multiple objects are incorrectly combined.
Feature integration theory
Proposed by Anne Treisman; focused attention is not required to detect the individual features that compromise a stimulus, such as color, shape, size, and location of letters, but it is required to bind those individuals features together.
Modular view
Specialized brain areas, or modules, detect and represent faces or houses or even body parts.
Distributed representation
Pattern of activity across multiple brain regions identifies any view viewed object, including faces.
Gestalt perceptual grouping rules
Govern how features and regions of things fit together.
G1) simplicity
Visual system tends to select the simplest or most likely interpretation.
G2) closure
Tend to fill in missing elements of a visual scene, allowing us to perceive edges that are separated by gaps as belonging to complete objects.
G3) continuity
When edges or contours have the same orientation, we tend to group them together perceptually.
G4) similarity
Regions that are similar in color, lightness, shape, or texture are perceived as belonging to the same object.
G5) proximity
Objects they are close together tend to be grouped together.
G6) common fate
Elements of visual images they move together are perceived as parts of a single moving object.
Perceptual grouping
Involved visually separating an object from its surroundings. In gestalt terms, this means identifying a figure apart from the (back)ground in which is resides.
Monocular depth cues
Aspects of a scene that yield info about depth when viewed with only one eyes.
MD1) relative size
Used to perceive distance.
MD2) linear perspective
Phenomenon that parallel lines seem to converge as they recede into the distance.
MD3) texture gradient
Fact that the size of the elements on a patterned surface grows smaller as the surface recedes from the observer.
MD4) interposition
When one object partly blocks another, you can infer that the blocking object is closer than the blocked object.
MD5) relative height in the image
Objects are closer to you are lower in your visual field, whereas faraway objects are higher.
automatic responses to stimuli
occurring entirely within the spinal cord. sensory neuron sends AP to spinal cord via axon and the interneuron sends its own msg to the motor neuron that sends an AP to release a neurotransmitter telling you to pull away. you pull away before the brain has even received info about the event.
kinesthetic sense
where you are in space and motion in space
binocular disparity
the difference in the retinal images of two eyes that provides info about depth
Ames room
trapezoidal in shape rather than square
Neural circuits in the brain
can detect the changes in retinal stimulation and responds to specific speeds and directions of motion
MT
region in the middle of the temporal lobe, part of the dorsal stream. specialized for the visual perception of motion and brain damage in this area leads to a deficit in normal motion perception
apparent motion
perception of movement as a result of alternating signals appearing in rapid succession in different locations.
change blindness
occurs when people fail to detect changes to the visual details of the scene. most likely to occur when people fail to focus attention on the changed object and is least likely to occur for items that draw attention to themselves
inattentional blindness
a failure to perceive objects that are not the focus of attention
pure tone
simple sound wave that first increases air pressure and then creates a relative vaccum.
3 physical dimensions of a sound wave that determine what we hear
frequency, amplitude, complexity
SW1) frequency (wavelength)
depends on how often the peak in air pressure passes the ear or microphone, measured in cycles per second, or hertz (Hz).
SW2) amplitude
refers to its height, relative to the threshold for human hearing.
SW3) complexity
mix of frequencies
pitch
changes in the physical frequency of a soundwave, how high or low the sound was.
loudness
sound’s intensity, corresponds to amplitude
timbre
a listener’s experience of sound quality or resonance.
the human ear is divided into 3 parts
the outer ear, the middle ear, and the inner ear.
outer ear
consists of the visible part on the outside of the head (called the pinna); the auditory canal; and the eardrum, an airtight flap of skin that vibrates in response to sound waves gathering by the pinna and channeled through the canal.
middle ear
tiny, air filled chamber behind the eardrum, contains the three smallest bones in the body, called ossicles.
ossicles
named for their appearance as a hammer, anvil, and stirrups. fit together into a lever that mechanically transmits and intensifies vibrations from the eardrum to the inner ear.
inner ear
contains the spiral shaped cochlea
cochlea
fluid filled tube that is the organ of auditory transduction. divided along its length by the basilar membrane.
basilar membrane
structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid. wave like movement stimulates thousands of tiny hair cells.
hair cells
specialized auditory receptor neurons embedded in the basilar membrane. release neurotransmitters molecules initiating a new neural signal in the auditory nerve that travels to the brain
area AI
portion of the temporal lobe that contains the primary auditory cortex. neurons in this area respond well to simple tones and successive auditory areas in the brain process sounds of increasing complexity
left auditory areas
analyze sounds relating to language
right auditory areas
specialize in rhythmic sounds and music
spatial (“where”) auditory features
allow you to locate the source of the sound in space and are handled by areas towards the back (caudal) part of the auditory cortex.
nonspatial (“what”) features
allow you to identify the sound and handled by areas in the lower (ventral) part of the auditory cortex
place code
mainly for high frequencies; different frequencies stimulate neural signals at specific places along the basilar membrane.
Low sound frequencies
Cause the wide, floppy tip (apex) of the basilar membrane to move the most.
High sound frequencies
Cause the narrow, stiff end (base) of the membrane to move the most.
Auditory axons
Axons fire the strongest in the hair cells along the area of the basilar membrane that moves the most and the brain uses this to determine which pitch you hear
Temporal code
Registers relatively low frequencies (up to 5000 Hz) via the firing rate of action potentials entering the auditory nerves. Action potentials from the hair cells are synchronized in time with the peaks of the incoming sound waves
Conductive hearing loss
Arises because the eardrum or ossicles are damaged to the point that they cannot conduct sound waves effectively to the cochlea.
Sensorineural hearing loss
Causes by damage to the cochlea, the hair cells, or the auditory nerve. Can be heightened in people regularly exposed to high noise levels. Amplify in the sound does not work bc the hair cells can no longer transfer sound wave. Cochlear implant might help
Cochlear implant
Electronic device they replaces the function of the hair cells. Sound picked up in microphone is transformed into electrical signals by the speech processor. Signal is transmitted to the implanted receiver which activated the electrodes in the cochlea
Somatosenses
Body senses
Haptic perception
Active exploration of the environment by touching and grasping objects with our hands.
Four types of receptors under skin allow us to sense
Pressure texture pattern or vibration against skin
Thermoreceptors
Nerve fibers that cold and warmth; respond when skin temp changes
Tactile brain
Devoted to parts of the skin surface they have greater spatial resolution.
What system for touch
Provides info about the properties of surfaces and objects.
Where system of touch
Provides info about a location in external space that is being touched or a location on the body that is being stimulated.
left hemispehre
(language) Broca’s area – produces languages; puts together in order, motor controls tongue, hand etc. for any form of language Wernicke’s area – language comprehension. You recognize the difference between a sneeze and a conversation. Analyzes sequences
right hemisphere
Emotion – takes in body language of others, controls your own expression. Big picture (don’t need to hear tone before seeing expression) Spatial relation – map inside your head, big picture.
External stimuli = sensory modalities
Light waves = eyes (sensors in retinal receptors) Sound waves = ears (receptors in the auditory system) Pressure, warmth, cold, pain = somtasensory receptors in skin etc. Chemical messengers = smell & taste Body position + movement = proprioception, vestibular system.
Congenital insensitivity to pain
Rare inherited disease that specifically impairs pain perception
A delta fibers
Transmit the initial sharp pain one might feel right away from a sudden injury.
C fibers
Transmit the longer lasting, duller pain that persists after the initial injury.
First Pain pathway
Sends signals to the somatosensory cortex, identifying where the pain is occurring and what sort of pain it is
Second pain pathway
Sends signals to the motivational and emotional centers of the brain, such as the hypothalamus and amygdala, and to the frontal lobe.
Referred pain
Sensory info from internal and external areas converge on the same nerve cells in the spinal cord
Gage control theory of pain
Signals arriving from pain receptors in the body can be stopped, or gated, by inter neurons in the spinal cord via feedback from two directions
Periaqueductal gray (PAG)
Region in the midbrain where inhibitory neural feedback comes from.
Bottom up control
Senses feed info such as pain sensations to the brain. Brains processes this sensory date into perceptual info at successive levels to support movement, object recognition, memory, and planning. | scientific explanation, begins w/ receptors and works up to integration.
Top down control
Visual illusions and the gestalt principles of filling in, shaping up, and rounding what isn’t really there. | Understanding stimuli based on prior expectation and experience. The brain will rapidly interpret stimuli based on their “most likely” explanation. influenced by biological, psychological, and sociocultural factors.
Receptors in the muscles, tendons, and joints
Signal the positions of the body in space, whereas info about balance and head movement originates in the inter ear
Vestibular system
The three fluid filled semicircular canals and adjacent organs located next to the cochlea in each inner ear. Canals are arranged in three perpendicular orientations and studded with hair cells that detect movement of fluid when the head moves. Bending of hair cells generates activity in the vestibular nerve which is conveyed to brain
Olfaction
Directly connected to the forebrain, with pathways into the frontal lobe, amygdala, and other forebrain structures. Indicates close relationship with areas involved in emotional and social behavior
visual cortex
respond to these features: color, movement, form, and depth in parallel. passed to the visual association areas of the occipital, parietal, and temporal loves for higher processing. indiv. features are integrated, resulting in perception of what we see.
gestalt psych
branch of cognitive psych. organization of many sensation into perception of a whole unit. based on experience and expectation. perceived whole is not always the same as its parts (illusions)
sensory adpation
Diminished sensitivity to a continuous stimulus. Allows for focus on relevant stimuli aka habituation (getting tattooed a lot, you get used to the pain)
Olfactory epithelium
Top of the nasal cavity, mucous membrane. Contains 10 million ORNs.
Olfactory receptor neurons (ORNs)
Receptor cells that initiate the sense of smell. Odors the molecules bind on sites on these receptors, and if enough binding occurs, the ORNs send action potentials into the olfactory nerve
Olfactory bulb
Brain structure located above the nasal cavity beneath the front lobes. Where ORNs send their axons from the olfactory epithelium. Sends outputs to various centers in the brain, including parts controlling drives, emotions, and memories
Pheromones
Biochemical odorants emitted by other members of a species that can affect an animals behavior and physiology
Papillae
Bumps that cover the tongue. Hundreds of taste buds within one
Taste buds
Orange of taste transduction. Tongue, roof of month, upper throat.
5 types of taste receptors
Salty, sour, bitter, sweet, and umami (savory).
Umami receptors
Discovered by Japanese scientists; attributed to foods containing a high concentration of protein, such as meats and cheeses.
Monosodium glutamate (MSG)
Activated umami receptors
Food molecules dissolved in saliva
Evoke specific, combined patterns of activity in the five taste receptor types
Tasters
50% of people who report bitter taste in caffeine, saccharine, certain green veggies etc
Non tasters
25% no bitter taste
super tasters
25% extremely bitter
