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96 Cards in this Set
- Front
- Back
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Sensation
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Receptors detecting stimuli
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Perception
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Organizing stimuli for understanding
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Sensory Transduction
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Transforming external stimuli into an electrical code (action potentials)
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Graded Electrical Potential
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Activation of the sensory receptor alters the membrane potential of a neuron producing a receptor potential
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Ways Neural Codes Differ
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Intensity, Quality, Duration
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Intensity
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Single neuron= # firings per unit of time
Population= # firings across neurons |
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Quality
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“labeled lines” individual primary afferent fibers carry information from a single type of receptor (taste)
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Duration
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Duration of response
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Principles Guiding the Interactions of Sensory Cortex
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Hierarchical Organization, Functional Segregation, Parallel Processing
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Hierarchical Organization
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Specificity and complexity increases with each level
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Functional Segregation
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Motion, color, etc. processed separately
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Parallel Processing
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Two primary systems working at the same time
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Perceptual Dimensions
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Hue, Brightness, Saturation
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Hue
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Color
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Brightness
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Intensity
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Saturation
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Purity of color of light
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# Light Receptors Per Eye
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130 million
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Rods
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120 million in retina
Most sensitive to light Can't see color Night vision Mostly in periphery of eye |
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Cones
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6 million in retina
Color vision Provides sharpness, acuity Daytime vision Mostly in fovea |
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Fovea
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Contains cones
Very detailed vision Few axons and cells in the way |
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Photoreceptors
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At rest are depolarized (-40mV), release glutamate
Graded potentials, no action potentials |
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Bipolar Cells
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Photoreceptors' glutamate release hyperpolarizes them
Light decreases glutamate from receptors and depolarizes bipolar cells and increase neurotransmitter release Graded potentials, no action potentials |
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Ganglion Cells
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Bipolar cells increase neurotransmitter release on ganglions resulting in ACTION POTENTIAL
Project to the brain |
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Horizontal and Amacrine Cells
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Interneurons that inhibit bipolar cells (horizontal) and ganglions (both)
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Image compression
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130 million receptors to 1.2 million ganglion cells
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Receptive Field
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A region of space in which the presence of a stimulus will alter the firing of that neuron
Circular or oval Often overlap One neuron can be in many receptive fields |
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How Receptive Fields Differ
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Precision: as to location
Attributes coded: color/form Amount of cortex: how much neural tissue responds to that input (more territory=better acuity) |
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Point-to-Point Topographic Organization
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Point on skin or retina projects to specific point in cortex
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Pathway of light from retina to V1
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Axons of retinal ganglion cells → optic nerve
→laternal geniculate nucleus → primary visual cortex (V1) |
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Simple Cells in Visual Cortex
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Respond to a line at one particular location
One specific orientation Small receptive field Receptive field has narrow excitatory area, flanked by symmetrical inhibitory areas |
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Complex Cells
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Respond to a bar of light in a specific orientation anywhere in the receptive field
Located in V1 and V2 Medium sized receptive fields |
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Lateral Geniculate Nucleus
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Primary relay center for visual information received from the retina.
Found in the thalamus 6 layers 2 magnocellular layers 4 parvocellular layers |
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Parvocellular (Ventral) Stream
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Derives from fovea where cones are
ganglions have small (parvo) cell bodies and SLOW transmission Important for discriminating details Recognition of visual objects Enables identification of shape and color The "what is it" pathway |
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Magnocellular (Dorsal) Stream
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Derives from periphery where rods are
Ganglions have large (magno) cell bodies and FAST transmission Pathway to parietal lobe Detects movement and sudden changes Informs movement system how to orient or manipulate an object The "where"/"how to" pathway |
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Lateral Inhibition
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A method of enhancing neural information in which each neuron's activity inhibits the activity of its neighbors, and in turn its activity is inhibited by them
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Amplitude
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Loudness/Intensity--Height of the wave--physical energy in a sound
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Frequency
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Pitch-- # of waves of alternating compression and decompression of the vibrating medium that occur in a second
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Complexity
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Timbre
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Cochlea
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Where the auditory stimulus is converted into neural impulses
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Frequency Range of Humans
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20 hertz -- 20,000 hertz
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Pinna
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Outer ear
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Organ of Corti
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sound-analyzing structure that rests on the basilar membrane
4 rows of specialized hair cells, their supporting cells, and the tectorial membrane above the hair cells |
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Hair cells
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Receptors for auditory stimulation
Basilar membrane vibrates, cochlear fluid bends hair cells, opening potassium and calcium channels depolarizing the hair cell |
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Inner Hair Cells
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Single row of 3,500 cells
Receive 90-95% of auditory neurons Provide majority of information |
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Outer Hair Cells
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Three rows of 12,000 cells
Amplify the signal of weak sounds Provide adjustable frequency selectivity |
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Pathway of Auditory Signaling
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From cochlea on each side → auditory nerve → brain stem nuclei (cochlear nucleus and superior olivary nucleus) → Midbrain: inferior colliculus → Thalamaus (medial geniculate nucleus) → auditory cortex
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Tonotopic map
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In the primary cortex, specific places process specific frequencies (like the cochlea)
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Sound Localization
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Binaural cues: using both ears
Sound intensity in one ear compared to the other Phase: low frequency sounds will be a different phase when they reach one ear compared to the other Timing: Sound directed to one ear takes .5 ms to reach the other ear |
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Somatosensory Systems
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Proprioceptive--body position
Interoceptive--body conditions Exteroceptive--external stimuli |
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Meissner's Corpuscle
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Small receptive field
Fast adapting Sense Vibration Touch |
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Merkel's Disk
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Small Receptive Field
Slow adapting (texture / fine detail) Touch Respond to gradual skin indentation |
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Pacinian Corpuscle/Ruffini Organ
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Large receptive field
Deep Pressure Detect stretching, shape Touch and pressure |
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Free Nerve Endings
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Small or large Receptive Fields
Pain (Chemical signals released at the damage site) Heat Cold Transient Receptor Potential (TRP) (Protein ion channels) |
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Somatosensory Cortex
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The larger the area the greater the acuity of processing
Input contralateral |
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Primary Somatosensory Cortex
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Supplies motor areas with information about the body, such as limb position
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Posterior Parietal Cortex
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Supplies motor areas with information about location of body parts in relation to objects in space
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Prefrontal Cortex
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Holds in memory information about the world and about the body while selecting appropriate movement and target
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Premotor Cortex
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Combines information needed for movement begins programming
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Supplementary Motor Area
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Assembles sequences of movements
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Cerebellum
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Contributes order and timing to intended movements, sends information back to motor cortex
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Primary Motor Cortex
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Executes movements
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Basal Ganglion
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Smooth motor movements
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Pheromones
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Chemicals given off by animals that have a physiological or behavioral effect on another animal of the same species
Most pheromones are detected by the Vomeronasal Organ (VNO) |
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# Human Odor Receptor Genes and Receptors
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Receptor Genes=350
Receptors=6 million |
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# of Human Detectable Odors
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10,000 odors
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Major Histocompatibility Complex
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Each human gives off a unique genetically determined odor. People can identify clothing worn by family members as opposed to strangers
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Olfactory sensory neurons
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2-3 synapses
direct path to limbic structures |
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Hypothalamus/Amygdala in Olfaction
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Motivational and emotional aspects of smell
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Hippocampus in Olfaction
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Odor memory
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Frontal Cortex
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Conscious perception of smell
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Fish Malodor Syndrome
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High levels of trimethylamine (TMA) released from skin, breath and urine
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Language
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The generation and understanding of written, spoken, and gestural communication
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Language related areas
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Broca's Area: speech production
Wernicke's Area: understanding speech and writing Motor Cortex: control facial and hand muscles Primary visual cortex: sends information to angular gyrus Angular Gyrus: reading and writing, relays info to and from Wernicke's |
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Aphasias
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Language impairment caused by brain damage
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Broca's Aphasia
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Non-fluent speech, purely a production problem
Speech formation Use of content words (verbs/nouns) but not grammatical connectors (function words) |
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Wernicke's Aphasia
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Fluent Speech, but meaningless
Problems understanding and producing spoken and written language Speech lacks content words Impaired repetition |
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Multiple Memory Systems
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Hippocampus: declarative memory
Amygdala: emotional memory Striatum: procedural memory |
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Episodic Memory
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Memory for the temporal organization of events in experiences
Distinct spatial memories are represented as sequences of events and places |
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Cognitive Mapping
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Dedicated navigational system that plots locations and integrates paths
Hippocampal cells indicate location in the environment |
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Arousal
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Activating sympathetic nervous system
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Parts of Brain involved with Emotion
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-Cingulate Gyrus: attention, cognitive processing and emotion, size can determine harm avoidance
-Prefrontal Cortex: final destination for information on emotion processing -Hippocampus: memory about emotional situations -Amygdala: fear and anxiety, happy faces and pleasant memories and sexually exciting stimuli -Hypothalamus: starts sympathetic nervous response |
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Hypothalamic-Pituitary-Adrenal Axis
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A complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland and the adrenal glands.
Controls reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality and energy storage and expenditure |
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Aggression
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Behavior intended to do harm
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Predatory Aggression
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Cold, emotionless
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Affective Aggression
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Emotional arousal
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Testosterone levels
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Can be 53-1500 ng/dl
Normal: 270-1070 ng/dl |
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Serotonin (5-HT) and Aggression
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Serotonin inhibits aggression
Depleted 5-HT increases aggression Alcohol facilitates aggression in people with low 5-HT |
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Melatonin
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A hormone that induces sleep
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Suprachiasmatic Nucleus (SCN)
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SCN in the hypothalamus
Is the pacemaker of the brain (keeps time) Regulates the pineal gland |
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Pineal gland
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Releases melatonin
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Brain Activity During Sleep Stage
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-Awake: fast, random neuron firing and low voltage
-Drowsy or relaxed: Slower neuron firing and start to synchronize -Stage 1 and 2: Even slower firing and more synchronizing -Stage 3 and 4: Slow wave sleep, highly synchronized Deep sleep -REM(Rapid Eye Movement): Fast and random firing with atonia |
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Atonia
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Muscle paralysis
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REM Stage
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20% of sleep cycle
80% of dreaming Atonia Increased breathing and heart rate Infants start sleep cycle in REM, are in REM 50% of time Memory: learning retention |
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Non-REM
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Restoration--Brain repair and other body maintenance
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Sleep Controls
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-Basil forebrain: Throughout the day adenosine increases
-Decreasing activity of arousal stimulating neurons -Preoptic area (POA): Adenosine build up to alter cells activity in this area -Ventrolateral POA: Doubles firing during sleep |
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Sleep Disorders
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Insomnia: inability to obtain quality sleep
Sleepwalking: during slow wave sleep Narcolepsy: falling into REM suddenly Cataplexy: sudden atonia but still awake REM sleep behavior disorder: REM without atonia, violently acting out dreams |
