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113 Cards in this Set
- Front
- Back
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Neuroscience Methods (3 Classes of Methodologies)
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1. Lesion
2. Stimulation 3. Recording |
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Lesion (as a Neuroscience Method)
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-remove or inhibit part of the brain
-measure change in behavior -ex. modality-specific retrograde amnesia in HM, who had trouble remembering years of life prior to removal of hippocampus; his autobiographical and spatial memory were impaired, but his skill memory was in tact |
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Stimulation (as a Neuroscience Method)
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-stimulate or activate part of the brain (by passing electrical current through, pouring on glutamate, etc.)
-measure change in behavior -thus can determine actions of certain parts of the brain |
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Recording (as a Neuroscience Method)
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-manipulate physiology or behavior
-measure change in brain activity (by recording directly from the brain) -recording methods include: CT, PET, fMRI, and electrophysiology |
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CT aka CAT Scan (as a Recording Method)
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-Computerized Axial Tomography
-inject radioopaque dye into bloodstream in order to increase resolution -pass x-rays through head (to measure the density of tissue) |
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PET Scan (as a Recording Method)
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-Positron Emission Tomography (radiation)
-inject dye or radiolabeled molecule into bloodstream (ex. usually glucose because it can cross the BBB) -measure radioactivity levels (because presumably suck up more glucose when working hard, so if one part of brain is engaged in the task/behavior, it will be the most radioactive - cells can't use the glucose that's radiolabeled right away) |
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fMRI (as a Recording Method)
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-functional Magnetic Resonance Imaging (current gold standard)
-create strong magnetic field around the head (measure changes in the magnetic character of brain tissue) -measure changes in magnetic nature of hemoglobin that accompany release of oxygen (which parts of the brain are using the most oxygen because those are the parts most active) -spin a strong magnet around and create a field thata sucks out any metal -structures can be seen as a map -need to use a projection map (flat) to compare across subjects because different folds of brain are set up slightly differently from one individual to another |
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Limitations of Recording Methods
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-PET has an accuracy of 1 cm
-MRI has an accuracy of 3-5 mm -Problem is that 1 sq. mm of cortex = 100,000 neurons (up to 250,000 in V1) |
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Historical Study of Brain and Behavior
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-Phrenology: phrenologists beleived that the cortex consisted of separate functional areas and each was responsible for a separate behavioral faculty; assertion that we're born with particular tendency, expressed in brain tissue and can be felt by bumps of head
-Broca: Paul Broca discovered that particular language deficits were correlated with damage to particular area of brain; in 1861, performed autopsy on "Tan" and published the first conclusive linkage between anatomical location and function -Later, Carl Lashley: made large lesions in the cortex of rats and measured maze behavior and incorrectly concluded that there were no specialized cortical areas and that instead the mass action hypothesis was correct in saying that all of the brain is responsible for all things -Later, more sophisticated techniques led to recordings of single cells and functional imaging in humans |
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Basic Terminology
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-Sagittal: slice down midline along lateral fissure or parallel to it
-Horizontal: slice from front to back, perpendicular to body -Coronal: slice from top to bottom along central gyrus or parallel to it -Dorsal: back surface, or top in brain Ventral: front surface or bottom in brain -Anterior: front (of brain) -Posterior: back (of brain) -Lateral: more towards side -Medial: more towards middle -Ipsilateral: on same side -Contralateral: on opposite sides -Gray Matter: contains mostly cell bodies; on outside of brain and inside of spinal cord -White matter: contains mostly myelinated axons; on inside of brain and outside of spinal cord -Ganglia: groups of cell bodies in the PNS -Nuclei: groups of cell bodies in the CNS |
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Spinal Anatomy
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-spinal cord communicates with sense organs, muscles, organs and glands BELOW THE HEAF
-the head is served by the cranial nerves, which are not contained in the spinal cord, and which also handle some functions of the body |
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Dorsal Roots
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-carry sensory information to the cord
-bodies of cell bodies of sensory neurons contained in the dorsal root ganglia |
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Ventral Roots
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-carry motor information from the cord
-cell bodies lie in the spinal cord |
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Divisions of the PNS
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1. Somatic Nervous System
2. Autonomic Nervous System |
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Somatic Nervous System
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-conveys messages from the sense organs to the CNS and from the CNS to the muscles and glands
-most "normal" behaviors |
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Autonomic Nervous System
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-conveys messages from the heart and other organs to the CNS and from the CNS to the heart and other organs
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Divisions of Autonomic Nervous System
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1. Sympathetic Nervous System
2. Parasympathetic Nervous System -truly, both systems are constantly active in a balance |
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Sympathetic Nervous System
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-handles responses to stressors
-prepares the heart and other organs for vigorous activity -ganglia are organized near cord; final link is in sympathetic chain ganglion |
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Parasympathetic Nervous System
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-system at rest
-counters the sympathetic system, brings body back down to rest and controls nonemergency activity of the heart and other organs -ganglia are dispersed, usually near the target organ |
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Hindbrain
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consists of medulla, pons, and cerebellum
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Cranial Nerves
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-12 pairs of nerves that enter and exit the CNS from the hindbrain and the midbrain
-some are sensory, some are motor, and some are both/mixed -they control all sensory and motor functions of the head and much of the parasympathetic control of the organs |
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Medulla
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-controls vital functions such as breathing and heart rate
-contains nuclei for some cranial nerves |
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Pons
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-functions in both motor control and sensory analysis
-includes the first stop for auditory information -contains nuclei for some cranial nerves |
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Cerebellum
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-"little brain"
-functions include balance, coordination, attention, timing, and probably many others -as many cells here as in rest of brain combined -motor outputs that require timing; intricately timed outputs and inputs |
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Raphe System
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-a nucleus of the hindbrain
-ascending control over attention |
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Reticular System
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-a nucleus of the hindbrain
-descending control over motor signals to the spinal cord -ascending controlover cortical arousal and attention -ex. handles REM sleep; dreaming inhibits descending motor output so you don't act out your dreams |
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Midbrain
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1. Tegmentum
-includes some cranial nerves nuclei and part of the reticular formation 2. Tectum -top of the midbrain -contains two sets of colliculi (round swellings) -superior colliculus: processes visual information -inferior colliculus: processes auditory information 3. a nucleus of the midbrain is the substantia nigra, which sends dopamine-releasing projections up to motor areas of the brain |
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Forebrain
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-everything else, including:
1. thalamus 2. hypothalamus 3. pituitary gland 4. basal ganglia 5. basal forebrain 6. hippocampus 7. neocortex |
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Thalamus
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-located at the center of the forebrain
-major relay for incoming sensory information, except olfaction |
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Hypothalamus
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-located below the thalamus
-at least 20 different nuclei -very important for motivated behaviors -especially for the Four F's: feeding, fighting, fleeing, f....mating |
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Pituitary Gland
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-part CNS and part gland
-located at the base of the hypothalamus -important in hormonal control of physiological processes in the body |
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Basal Ganglia
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-located lateral to the thalamus and below the cortex
-important for planning motor movements and for some cognitive processes |
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Basal Forebrain
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-on the ventral surface of the forebrain
-important for arousal and attention -base of frontal cortex -implicated in Alzheimers |
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Hippocampus
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-lies along the ventricles between the thalamus and the cortex
-important for memory and spatial behaviors -c-shaped structure -episodic/autobiographical memory -memorizing/storing spatial maps -example: HM |
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Neocortex
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-aka cerebral cortex
-gray matter(cell bodies) that comprises the outer surface of the cerebral hemispheres -columnar organization -outer 6mm of cortex -each column processes a very specific stimulus |
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Ventricles
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-fluid-filled spaces
-contain CSF -control distribution of solutes in the CNS (act as ionic reservoir) -act as a shock absorber -4 of them, all interconnected: 2 lateral, 3rd and 4th |
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Cerebral Cortex Organization
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-is organized in layers called laminae
-up to 6 distinct laminae in each thickness of cortex (neocortex always has 6 layer, each with a distinct function, and the rest, paleocortex, can have 3 layers) -4 is major sensory input, so thick in cortex that performs a lot of sensory processing -5 is major motor output, so thick in cortex that controls a lot of motor functions |
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Columnar Organization in Visual Cortex
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-each column of cortex is specialized for a particular function
-in the visual cortex, different columns respond to different: 1. visual fields 2. orientations of lines 3. colors |
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Lobes of the Brain
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1. Occipital
2. Parietal 3. Temporal 4. Frontal |
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Occipital Lobe
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-main area for receiving visual input
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Parietal Lobe
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-main area for sensory input from the touch receptors, strecth receptors, and joints
-contains a number of somatotopic maps, each processing a different kind of input: touch, pressure, etc. -postcentral gyrus: primary target area on central cortex for touch and other skin sensations |
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Temporal Lobe
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-main area for auditory input
-essential for understanding spoken language -contains a number of other structures involved in emotion (amygdala) and memory (hippocampus) |
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Frontal Lobe
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-contains both primary motor cortex and the prefrontal cortex
-primary motor cortex is the main cortical output for movement -prefrontal cortex received sensory information from all modalities; important for integrating information -important for working memory, ex. delayed match to sample task |
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Retina
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-rear surface of the eye
-lined with photoreceptors |
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Lens
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-bends in response to contraction of ciliary muscles, in order to focus the image on the retina
-makes minor adjustments in the image |
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Fovea
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-part of the retina with the greatest ability to resolve detail (sharpest detail)
-no vasculature -tightly packed receptor cells -reduced number of other cells -light goes directly to the receptor cells without having to pass through other things -each receptor contacts a single bipolar cell, which then contacts a single ganglion cell, which sends one axon to the brain, thus: each receptor has its own line to the brain -our fovea is focused ahead; a hawk's or an owl's is focused downward; a mouse's is focused upward |
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Blind Spot
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-formed by the optic nerve
-area of the retina that lacks receptors -we actively fill in the blind spot |
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Optic Nerve
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-contains axons of ganglion cells and carries information out of the eye and to the brain
-goes to the lateral geniculate nucleus, superior colliculus, etc. |
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Receptors
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-sensory receptors use receptor potentials to transduce a stimulus
-all receptors contain photopgments, which release energy when struck by light |
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Receptor Potential
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-voltage difference between the inside and the outside of the cell that results from receiving a stimulus
-types: 1. graded with a stimulus 2. passive 3. local |
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Transduce
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-to turn one type of energy into another
-receptors turn various stimulus energies into electricity |
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Flow of Information in the Eye
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1. visual receptors transduce light energy
2. receptors modulate the activity of bipolar cells 3. bipolar cells send information to the ganglion cells 4.ganglion cells send information to the brain 5. activity in these cell types is further modulated by horizontal cells and amacrine cells So: light → receptors → bipolar cells → ganglion cells → brain |
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Cones
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-4 million
-most abundant in the fovea, and get less and less compact as move toward the periphery -respond best to bright light -responsible for color vision (because of the types of photopigments) -each cell has only one photopigment, but three types in cones -ratio of cones to bipolar cells closer to 1:1 |
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Rods
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-100 million
-most abundant in the periphery -respond to low levels of light -not very useful in bright light -have one type of photopigment -very sensitive, and thus easily saturated -rods have poor resolution; pool resources → give only general area -when in low light, put object of interest in periphery -multiple rods share one bipolar cell, so pixelated perception |
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Trichromatic Theory of Color Vision
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-primary light colors are: red, green, and blue
-behavioral evidence: human subjects can match any perceived color by matching 3 individual wavelengths -physiological evidence: there really are 3 different types of cone cells that each respond maximally to different wavelengths of light (called high/long, medium, and low/short) -however, they each respond to a range of light wavelengths and the peaks are not exactly what was predicted by the original trichromatic theory |
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Opponent-Process Theory of Color Vision
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-the brain perceives light according to 3 opponents:
1. white to black 2. red to green 3. blue to yellow -behavioral evidence: subjects report negative after-images according to these opponents -physiological evidence: bipolar cells are excited by one wavelength and inhibited by another along these scales |
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Color Constancy (Other Theories of Color Vision)
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-ability to perceive colors as constant despite changes in illumination
-example: know that something partly covered in shadow is still the same color |
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Retinex Theory (Other Theories of Color Vision)
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-states that the cortex compares information from various parts of the retina and then adjusts the perception of color and brightness for each area of the visual field
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Central Processing of Visual Information: The Basics
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-rods/cones send information to the ganglion cells
-ganlion cells send information to: 1. lateral geniculate nucleus of the thalamus 2. superior colliculus 3. other areas of the thalamus -the lateral geniculate nucleus sends information to: 1. other parts of the thalamus 2. the visual cortex -the visual cortex sends information to: 1. other areas of visual cortex 2. back to the thalamus -left half of brain processes right half of world and vice versa, but each eye sees both, so split each image into two halves |
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VIsual Field
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-part of the world that can be seen at any given time
-there is a right visual field and a right visual field -these refer to the center of the person: the right visual field = right side of the person |
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Receptive Field
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-part of the visual field that any given neuron "sees" or responds to
-each neuron has a receptive field that is some part of the visual field |
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Early Processing
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-processing starts to get complex early on, at the level of the ganglion cell:
1. some ganglion cells are on-center: excited by stimuli in the center of their receptive field 2. some ganglion cells are off-center: inhibited by stimuly in the center of their receptive field -there are overlapping receptive fields, which allows for great detail because huge difference in signalling based on a very small difference in distance/placement |
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On-Center
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-ganglion cells that are excited by stimuli in the center of their receptive fields
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Off-Center
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-ganglion cells that are inhibited by stimuli in the center of their receptive fields
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Rods/Cones excite two "sets" of cells:
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1. bipolar cells (sometimes via amacrine cells)
2. horizontal cells |
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Bipolar Cells
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-send information further up the line to the ganglion cells, etc.
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Horizontal Cells
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-are responsible for sharpening contrasts through lateral inhibition
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Lateral Inhibition
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-horizontal cells can inhibit a wide stretch og bipolar cells
-as a result, activity in one bipolar cell is associated with inhibition of its neighbors -the inhibition of neighbors results in a sharpening of contrasts at the edges of a stimulus -so can get" moderately excited, really excited, moderately inhibited, and really inhibited |
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Types of Primate Ganglion Cells
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1. Parvocellular
2. Magnocellular 3. Koniocellular |
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Parvocellular
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-small cell bodies and receptive field
-located mostly near the fovea (have private lines from the cones) -detect visual details -highly sensitive to color -connect to lateral geniculate nucleus of the thalamus |
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Magnocellular
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-large cell bodies and receptive fields
-located throughout the retina (widely dispersed -detect motion and patterns -insensitive to color -connect to lateral geniculate nucleus of the thalamus and other areas of the thalamus |
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Koniocellular
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-small cell bodies and receptive fields
-located throughout the retina -various functions (least well-known) -connect to lateral geniculate nuclues of the thalamus and other areas of the thalamus and superior colliculus |
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Primary Visual Cortex = V1
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-responsible for the first stage of cortical processing
-responds to any kind of visual stimulus and is active during visual imagery (imagination) -V1 sends information to V2 |
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V2
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-responsible for further processing
-responds to particular forms and illusory contourr, which are perceived visual stimuli that are not actually there -one V2 for dorsat half of world and another for ventral half -after V2, the parvocellular and magnocellular cortical projections split off |
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Cortical Pathways
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-after V2, magnocellular and parvocellular cortical projections split off:
1. one pathway, mostly carrying information from the parvocellular pathway, is sensitive to the details of shape 2. one pathway, mostly carrying information from the magnocellular pathway, is sensitive to movement and is important for integrating vision and action 3. one pathway, with mixed parvocellular and magnocellular information, is sensitive to brightness and color (identifying characteristics of an object -the parvocellular pathway is othersise known at the what pathway (identity of object) -the magnocellular pathway is otherwise known as the where pathway (location of object in space) -it seems that these may actually be split at the level of the ganglion cell input, even though it seems input is the same going into V2 |
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What and Where Experiment
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-Ungerleider and Mishkin (1982)
-Monkeys perform two different short-term memory tasks, each dependent on either remembering "what" or "where" -"what" task is object discrimination -"where" task is landmark discrimination -both dorsal (where) and ventral (what) pathways branch out from V1 |
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Object Discrimination (What)
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-monkey is shown one object
-after some short delay, the monkey is given a choice between two objects -it must choose the object previously seen -has difficulty remembering what is shown if temporal area/ventral pathway is removed, but can perform where task |
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Location Discrimination (Where)
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-monkey is shown a landmark and a corresponding relative location of food
-after some short delay, the monkey is given a choice between two locations -it must choose the location previously seen -has difficulty remembering where if the parietlal cortex/dorsal pathway has been removed, but can perform what task |
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Cortical Cell Types: Method
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-measure action potentials and find out what receptive fields are
-projection on screen → cat → microelectrodes hooked up → amplifier → oscilliscope → record of response (neural spikes) |
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Cortical Cell Types
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1. SImple Cells
2. Complex Cells 3. Hyper-Complex Cells |
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Simple Cells
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-contained in V1
-receptive field has a single, fixed excitatory portion and an inibitory surround (have a very simple thing that they like -shape of the excitatory or inhibitory portions are different for different simple cells -most respond to bars or line, or areas near bars or lines -highly sensitive because they will pick out orientation and direction of line they will respond to |
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Complex Cells
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-get their input from the simple cells (one synapse down)
-contained in both V1 and V2 -receptive fields cannot be mapped into fixed excitatory and inhibitory zones (like complicated things) -example: one type responds to a particular orientation (like a simple cell), but does so regardless of location within the receptive field (unlike a simple cell) -"I like rectangles, but I don't care where they are" |
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Hyper-Complex Cells
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-cells that are more complex than complex cells
-that is, they contain all of the features of complex cells, plus at least one more -typically, the added feature is an area of strong inhinbition -"I like rectangles no matter where they are except for here" -exclusionary logic → high levels of processing |
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Cortical Columns
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-cells are organized into columns in the cerebral cortex
-cells within a single column typically have the same characteristics (shape of excitatory field, motion sensitivity, etc.) -usually respond to either left or right eye (called Ocular Dominance) |
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Spatial Frequency Filter Model
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-V1 cells are sensitive to gratings of a particular frequency; each cell likes a different frequency and frequency can be used to recognize an object
-spatial frequency is the number of light and dark (or color) cycles per degree of visual space -perhaps the CNS has different spatial frequency channels for analyzing visual data -visual cortex uses calculus to extract series of sine waves from complicated waveforms -evidence: V1 does contain cells that are responsive to particular spatial frequencies and subjects do adapt to particular spatial frequencies |
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Shape Analysis
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-in V2, which is responsible for shape perception, some cells respond to particular patterns of stimulation: line conjunctions, circles, etc.
-in V4, many cells respond to dimensions/depth |
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Disorders of Object Recognition
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1. Visual Agnosia
2. Prosopagnosia |
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Visual Agnosia
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-inability to recognize objects
-typically, the patient can describe the features of an object, but cannot name the object |
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Prosopagnosia
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-inability to recognize faces
-the fusiform gyrus may be specialized for face recognition: cells there respond to a variety of stimuli, but respond most strongly to faces |
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Mechanical Sensation
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-includes audition, vestibular sensation, and somatosensation
-a sense for which the receptor cells are physically distorted by the stimulus (mechanical pressure from energy of the real world) |
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Chemical Sensation
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-includes gustation and olfaction
-a sense for which the receptor cells detect chemical(s) in the stimulus (chemical components from real world act on chemical receptors on sense cells) |
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Parts of the Ear
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1. Outer Ear
-Pinna = the eat 2. Middle Ear -tympanic membrane (eardrum) -middle ear bones: transmit vibration from eardrum to Oval Window 3. Inner Ear -the cochlea -contains a fluid that is displaced when the oval window vibrates, which then displaces hair cells |
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Characteristics of Auditory Stimuli
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1. Amplitude: intensity of a soundwave, measured in dB
2. Frequency: compressions (cycles) per second, measured in Hz 3. Loudness: perception of amplitude/intensity 4. Pitch: perception of frequency |
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Theories of Auditory Processing
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1. Frequency Theory
2. Place Theory 3. Combined Theory |
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Frequency Theory (of Auditory Processing)
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-basilar membrane vibrates in synchrony with the stimulus
-auditory axons produce action potentials at the same frequency -pitch is derived from action potential freqeuncy -problem because frequency of hearing goes beyond frequency of action potential firing ability -at higher frequencies, a bunch of cells combine efforts to keep up with the stimulus (Volley Principle) |
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Place Theory (of Auditory Processing)
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-different parts of the basilar membrane vibrate at different frequencies
-the vibrating part produces action potentials -pitch is derived from action potential origin (in cochlea) -so not how many APs, but where they come from |
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Combined Theory (of Auditory Processing)
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-at low frequencies, system uses frequency/volley
-at higher frequencies, system uses place -in between, uses in between (500-5000 Hz) |
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Hair Cells
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-lie in the cochlea and are mechanically displaced when the fluid in the cochlea moves
-when processes on the hair cell are displaced, ion channels in the membrane open up and let K into the cell -this works because cochlear fluid has high K concentration on outside, so it wants to get into hair cells (not like in neurons where it is leaking out) |
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Auditory Information
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-is bilateral above the level of the inferior colliculus
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Primary Auditory Cortex
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-located in the temporal lobe
-some cells in the PAC have spatial receptive fields -some cells in the PAC have frequency receptive fields -damage to PAC does not cause deafness, but does injure ability to recognize combinations or sequences of sound (such as music or speech) |
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Conductive Deafness
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-middle ear deafness
-failure in transmission in the bones of the middle ear -caused by disease/infection or malformation of the bones of the inner ear -can be somewhat alleviated by hearing aids |
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Nerve Deafness
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-inner ear deafness
-failure in cochlea, hair cells, or auditory nerve -caused by disease or prenatal problems -can be somewhat alleviated by hearing aids -also, cochlear implant where you insert electrodes |
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Sound Localization
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1. Interaural intensity difference
-best for high frequencies 2. Interaural timing difference -especially for stimuli with quick onset, because arrives at one ear before the other 3. Interaural phase difference -best for low frequencies, because at higher frequencies, harder to distinguish different points -only works at particular angles -none of these works particularly well for sounds that come from right in front or in back of us |
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Vestibular Sensation
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1. vestibular organ:
-2 otolith organs -3 semicircular canals 2. otolith: "ear stone" -small calcium carbonate particles -otolith measures head tilt -how? rocks displace hair cells, and brain knows angle of tilt 3. semicircular canal: -contains fluid and hair cells (like in cochlea) -measures head acceleration |
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Taste Receptors
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-hybrid skin cells that are similar to both neurons and skin cells
-excitable, release transmitter -high turnover (replaced with high frequency) -first cells in chain do not produce APs, but do respond to graded potentials and release transmitter |
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Types of Taste Receptors
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1. Salty
2. Sour 3. Sweet 4. Bitter 5. Umami |
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Salty Receptors
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-receptors have Na channels that are relatively permeable to the sodium contained in salt (Na just leaks in)
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Sour Receptors
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-receptors have K channels that have binding sites for acids
-binding closes the channel, which prevents K from leaking out, thus increasing the potential |
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Sweet, Bitter, and Umami Receptors
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-receptors have specialized binding sites that are coupled to metabotropic mechanisms (G-proteins)
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Taste Perception
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-there are only 5 primary tastes that we know of
-to distinguish between different stimuli, the brain must compare responses of a large number of receptors -the integration begins at the first cell (the target of the receptor cells) |
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Taste Nerves
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-project to the nucleus tractis solitarius (solitary nucleus or NTS) in the medulla
-NTS projects to: 1. Cortex -insular cortex (primary taste cortex, aka G1) -primary somatosensory cortex (somatosensation) 2. hypothalamus and amygdala (emotion and motivation) -helps determine the emotional valence of the stimulus, ex. taste aversion |
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Olfaction
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-receptors are the olfactory cells of the olfactory epithelium
-epithelium, bulb, cortex, are organized topographically (like the nose has a map of chemical world) -each receptor cell has only one type of receptor molecule -mechanism is metabotropic -humans have hundreds (about 700) of different receptor proteins, whereas rats have thousands -smell is the sense that we have the widest variety of receptors for! |
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Olfaction: Pheremones
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1. pheremone receptors respond to: chemicals that are released by animals that are designed to affect the behavior of other members of their species
2. pheremone effects -female secretions promote synchronization of cycle -male secretions promote regularity of cycle -we don't know how the effects are transduced |
