Chapter 3 Flashcards
Nervous system
- central nervous system (CNS): brain and spinal cord
- peripheral nervous systen (PNS): connects the brain and spinal cord to the rest of the body, includes somatic nervous system and the autonomic nervous system
central nervous system
central nervous system (CNS): brain and spinal cord
peripheral nervous systen
peripheral nervous systen (PNS): connects the brain and spinal cord to the rest of the body, includes somatic nervous system and autonomic nervous system
somatic nervous system
part of peripheral nervous system, consists axons conveying messages from the sense organs to the CNS and from the CNS to the muscles
autonomic nervous system
Another part of the PNS, the autonomic nervous system, controls the heart, intestines, and other organs. The autonomic nervous system has some of its cell bodies within the brain or spinal cord and some in clusters along the sides of the spinal cord.
Dorsal
Toward the back, away from the ventral (stomach) side. The top of the brain is considered dorsal because it has that position in four-legged animals.
Ventral
Toward the stomach, away from the dorsal (back) side
Anterior
Toward the front end of the brain
Posterior
Towards the backside of the brain
Superior
above another brain part
Inferior
below another brain part
lateral
towards the side of the brain, something located away from the middle part of the brain
medial
Toward the midline, away from the side
proximal
Located close (approximate) to the point of origin or attachment
distal
Located more distant from the point of origin or attachment
Ipsilateral
On the same side of the body (e.g., two parts on the left or two on the right)
Contralateral
On the opposite side of the body (one on the left and one on the right)
Coronal plane (or frontal plane)
A plane that shows brain structures as seen from the front
Sagittal plane
A plane that shows brain structures as seen from the side
Horizontal plane (or transverse plane)
A plane that shows brain structures as seen from above
Lamina
A row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites
Column
A set of cells vertical to the surface of the cortex, with similar properties
Tract
A set of axons within the CNS, also known as a projection. If axons extend from cell bodies in structure A to synapses onto B, we say that the fibers “project” from A onto B.
Nerve
A set of axons in the periphery, either from the CNS to a muscle or gland or from a sensory organ to the CNS
Nucleus
A cluster of neuron cell bodies within the CNS
Ganglion
A cluster of neuron cell bodies, usually outside the CNS (as in the sympathetic nervous system)
Gyrus
A protuberance( = Austülbung) on the surface of the brain
Sulcus
A fold or groove that separates one gyrus from another
Fissure
A long, deep sulcus= long, deep fold or groove that separates one gyrus from another
spinal cord
- part of the CNS within the spinal column
- communicates with all the sense organs and muscles except those of the head.
- segmented structure, each segment has on each side a sensory nerve and a motor nerve; entering dorsal roots (axon bundles) carry sensory information, and the exiting ventral roots carry motor information
- gray matter in center of the cord, packed with cell bodies and dendrites: neurons from gray matter send axons to the brain or to other parts of spinal cord through white matter
dorsal root ganglia
ganglia = pl. ganglion : cell bodies of sensory neurons in clusters of neurons outside the spinal cord
- Cell bodies of the motor neurons are inside the spinal cord.
sympathetic nervous system
network of nerves that prepare organs for activity, consists of chains of ganglia just to the left and right of the spinal cord’s central regions (the thoracic and lumbar areas)
- Sympathetic axons prepare the organs for “fight or flight”: increasing breathing and heart rate
- sympathetic ganglia are closely linked, they often act as a single system “in sympathy”
- Most sympathetic nervous system axons release norepinephrine, besides those on sweat glands : acetylcholine
parasympathetic nervous system
facilitates vegetative, nonemergency responses (opposite of sympathetic activities, ex. decreasing heart rate,conserving energy)
- promotes sexual arousal, erection in males
- also known as craniosacral system because it consists cranial nerves and nerves from the sacral spinal cord
- long preganglionic axons extend from spinal cord to parasympathetic ganglia close to each organ
- shorter postganglionic fibers then extend from the parasympathetic ganglia into the organs themselves
- parasympathetic nervous system’s axons release neurotransmitter acetylcholine onto the organs
hindbrain
- the posterior part of the brain,
- consists of the medulla, the pons, and the cerebellum
brainstem
- structure extend from the top of the spinal cord into the center of the forebrain
- medulla and pons, the midbrain, and certain central structures of the forebrain constitute the brainstem
medulla
- just above the spinal cord, regarded as an enlarged extension of the spinal cord into the skull
- controls vital reflexes (breathing, heart rate, vomiting, salivation, coughing, sneezing) through cranial nerves
cranial nerves
- 12
- control sensations from the head, muscle movements in the head, and much of parasympathetic output to organs
- connect receptors and muscles of the head and organs to the brain
- each cranial nerve originates in a nucleus (cluster of neurons), integrates sensory information and/or regulates motor output
cranial nerves (all 12 detailed)
I. = Smell II. = Vison III. = Control eye movements, pupil constriction IV. = Control eye movements V. = facial skin sensation, control muscles chewing, swallowing VI. = Control eye movements VII. = Taste from anterior two thirds of tongue, control of facial expressions, crying, salivation, dilation of head’s blood vessels VIII. = Hearing; equilibrium IX. = Taste, other sensations from throat posterior third of the tongue; control swallowing, salivation, throat movements during speech X.= Sensations from neck and thorax; control throat, esophagus, and larynx; parasympathetic nerves to stomach, intestines, and other organs XI. = Control of neck and shoulder movements XII. = Control of muscles of the tongue
Pons
- lies anterior and ventral to medulla
- contains nuclei for several cranial nerves.
- “bridge” = axons from each half of brain cross to opposite side of spinal cord : the left hemisphere controls muscles of the right side of body, right hemisphere controls the left side.
Cerebellum
- control of movement, important for balance and coordination, shifting attention back and forth between auditory and visual stimuli, timing, detecting alterations in rhythm
Midbrain
- small area
- contains tectum (roof of midbrain), inferior colliculus (important for hearing) and superior colliculus (important for vision)
- tegmentum lies under tectum and covers other midbrain structures
- substantia nigra gives rise to dopamine-containing pathway, facilitates readiness for movement
Forebrain
- 2 cerebral hemispheres, connected through corpus callosum
- hemispheres: receive sensory information from the contralateral (opposite) side of body, and control mus- cles on the contralateral side (through axons to spinal cord and the cranial nerve nuclei)
- The outer portion = cerebral cortex
- thalamus, basal ganglia, limbic system ( hippocampus, amygdala, olfactory bulb, hypothalamus, mamillary body, cingulate gyrus, thalamus )
Limbic system
- interlinked structure around the brain stem
- structures important for motivations and emotions, such as eating, drinking, sexual activity, anxiety, and aggression
Thalamus
- in the center of forebrain
- 2 round structure joined side by side, one in the left hemisphere and one in the right
- Most sensory information goes first to thalamus, processing info and sends output to cerebral cortex
(exception: olfactory info because of own route) - cerebral cortex sends info back to thalamus, prolonging and magnifying certain kinds of input and focusing attention on particular stimuli
- thalamus and hypothalamus form diencephalo = section distinct from the telencephalon ( rest of the forebrain)
Hypothalamus
- small area ventral to the thalamus
- widespread connections with the rest of the brain.
- communicates information to pituitary glands partly through nerves and partly through hypothalamic hormones, thereby altering its release of hormones
- involved in motivated behaviors (feeding, drinking, temperature regulation, sexual behavior, fighting, activity level)
Pituitary gland
- endocrine (hormone-producing) gland attached to the base of the hypothalamus by a stalk that contains neurons, blood vessels, and connective tissue
- responses to messages from hypothalamus, synthesizes hormones that the blood carries to organs throughout the body
Basal ganglia
- group of subcortical structures lateral to the thalamus,
- three major structures: the caudate nucleus, the putamen, and the globus pallidus
- important for movement, involved in diseases such as Parkinson
- integrates motivational and emotional behavior to increase the vigor of selected actions. However, the role of the basal ganglia extends beyond movement.
- critical for learning and remembering skills and habits, and other types of learning
Nucleus basalis
- receives input from the hypothalamus and basal ganglia and sends axons that release acetylcholine to widespread areas in the cerebral cortex
- key part of the brain’s system for arousal, wakefulness, and attention
- inactivity or deterioration of their nucleus basalis involved in impairment of intellect and attention in people with parkinson and alzheimer
Hippocampus
- word meaning “sea horse” because of shape
- large structure between the thalamus and the cerebral cortex
- is critical for certain types of memories, especially memories for individual events.
central canal
-fluid-filled channel in the center of the spinal cord
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ventricles,
- four fluid-filled cavities within the brain
- each hemisphere contains one of the two large lateral ventricles
- toward their posterior, they connect to the third ventricle, positioned at the midline, separating the left thalamus from the right thalamus.
- The third ventricle connects to the fourth ventricle in the center of the medulla.
- inside the four ventricles are cells called the choroid plexus which produce cerebrospinal fluid
cerebrospinal fluid ( CSF)
-clear fluid similar to blood plasma.
-fills ventricles, flowing from the lateral ventricles to the third and fourth ventricles.
-from fourth ventricle, some of it flows into the central canal ( spinal cord), but more goes into the narrow spaces between the brain and the thin meninges, (membranes that surround the brain and spinal cord)
In subarachnoid space, the blood gradually reabsorbs the CSF
- meninges have pain receptors (Swollen blood vessels in meninges are responsible for pain of a migraine)
-cushions the brain against mechani- cal shock when the head moves
- provides buoyancy
-helps support the weight of the brain
- provides a reservoir of hormones and nutrition for the brain and spinal cord.
meninges
membranes that surround the brain and spinal cord
- have pain receptors
- swollen blood vessels in meninges are responsible for pain of a migraine
hydrocephalus
- condition in which flow of CSF is obstructed, accumulates within the ventricles or in the subarachnoid space, increasing pressure on the brain. When this occurs in infants, the skull bones spread, causing an overgrown head
- can lead to mental retardation, although the results vary from one person to another.
Cerebral cortex
- most prominent part of the brain
- cells on the outer surface of cerebral cortex are gray matter and their axons extending inward are white matter
- neurons in each hemisphere communicate with each other through corpus callosum (two bundles of axons) and the anterior commissure
laminae
- layers of cell bodies that are parallel to the surface of the cortex and separated from each other by layers of fibers
- vary in thickness and prominence from one part of the cortex to another
columns
cells of the cortex are also organized into columns of cells perpendicular to the laminae
- Each column extends through several laminae
- Neurons within a given column have similar properties
- areas named as lobes
the 4 lobes of the cerebral cortex
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
occipital lobe
- main target for visual information
- posterior pole of occipital lobe is known as the primary visual cortex, or striate cortex, because of striped appearance in cross-section
- destruction of any part of the striate cortex causes cortical blindness in related part of visual field (ex. damage to right hemisphere causes in left visual field)
parietal lobe
- monitors all the information about eye, head, and body positions and passes it on to brain areas that control movement
- important for interpreting visual and auditory information
- essential not only for spatial information but also numerical information
- area just posterior to the central sulcus, the postcentral gyrus, or primary somatosensory cortex, receives sensations from touch receptors, muscle-stretch receptors, and joint receptors
- If during brain surgeons they lightly stimulate the postcentral gyrus, people report tingling sensations on the opposite side of the body
temporal lobe
- lateral portion of each hemisphere, near the temples
- primary cortical target for auditory information
- human temporal lobe (mostly the left temporal lobe) is essential for understanding spoken language
- contributes to complex aspects of vision, including perception of movement and recognition of faces
- tumor in temporal lobe may give rise to auditory or visual hallucinations
- also important for emotional and motivational behaviors.
Klüver-Bucy syndrome
- failing to display normal fears and anxieties after temporal lobe damage
frontal lobe
- containing primary motor cortex and prefrontal cortex
- posterior portion of the frontal lobe, the precentral gyrus, is specialized for the control of fine movements, such as moving one finger at a time.
- Separate areas are responsible for different parts of the body, mostly on the contralateral side but also with slight control of the ipsilateral side
- precentral gyrus = primary motor cortex
- most anterior portion of frontal lobe is the prefrontal cortex
- dendrites in prefrontal cortex have 16 times as many dendritic spines as neurons in other cortical areas, that why the prefrontal cortex integrates an enormous amount of information
prefrontal lobotomy
- surgical disconnection of the prefron- tal cortex from the rest of the brain
- was common between 1940-1960 in the states as therapy against mental disorders such as schizophrenia ( Freenman, untrained guy)
- common consequenceswere apathy, a loss of the ability to plan and take initiative, memory disorders, distractibility, and a loss of emotional expressions and social inhibition
prefrontal cortex
- contributes to many functions such as attention, working memory,
- People with damage to the prefrontal cortex have trouble on the delayed-response task, in which they see or hear something, and then have to respond to it after a delay
- also important for decision making and planning movements; consider difficulty of the action, the probabilities of success and failure, cells in the prefrontal cortex respond to all these complex factors
- unexpected outcomes highly arouse many of these cells, as they update their response- outcome predictions
- People with prefrontal cortical damage often make decisions that seem impulsive, because they failed to weigh all the likely pros and cons.
binding problem
binding problem, also called large-scale integration problem
- occurs if you perceive two sensations as happening at the same time and in approximately the same place
ex. : when dummy’s mouth moves at the same time as speech of some trained person, in nearly the same place, you perceive the sound as coming from the dummy -> visual stimulus alters the response of the auditory cortex, so that the sound really does seem to come from the same location as the dummy’s mouth
4 purposes of research methods on the brain
- Examine the effects of brain damage. After damage or temporary inactivation, what aspects of behavior are impaired?
- Examine the effects of stimulating a brain area. Ideally, if damaging some area impairs a behavior, stimulating that area should enhance the behavior.
- Record brain activity during behavior. We might record changes in brain activity during fighting, sleeping, finding food, solving a problem, or any other behavior.
- Correlate brain anatomy with behavior. Do people with some unusual behavior also have unusual brains? If so, in what way?
Transcranial magnetic stimulation (TMS)
-magnetic stimulation to a portion of the scalp, inactivates neurons in a narrow area below the magnet, producing a “virtual lesion” that outlasts the magnetic stimulation itself -procedure enables researchers to study behavior with some brain area active, then inactive, and then active again.
optogenetics
- using light to control limited population of neurons
- First researcher uses specially manipulated virus to insert light-sensitive proteins into the membrane of a given type of neuron. One protein reacts to light by opening a sodium channel, exciting the neuron. Another reacts by opening a chloride channel, producing inhibition.
- virus can be altered chemically so that it delivers one of these proteins only to a certain type of neuron, or even to just one part of the neuron, such as the axon or the dendrites
- very thin optical fiber is implanted into the brain, making it possible to shine light that affects only the type of neuron containing the light-sensitive protein
- excitation or inhibition of those cells in small brain area with millisecond accuracy can then be controlled.
- greater detail than ever before
recording brain activity
- PET
- EEG
- MRI
- FMRI
- MEG
electroencephalograph (EEG)
- records electrical activity of the brain through electrodes attached to the scalp
- Electrodes glued to the scalp measure the average activity at any moment for the population of cells under the electrode. The output is then amplified and recorded
evoked potentials/results
results of brain activity in response to a stimulus
magnetoencephalograph (MEG)
- measures the faint magnetic fields generated by brain activity
- Like EEG, an MEG recording identifies the approximate location of activity to within about a centimeter
- excellent temporal resolution, showing changes from one millisecond to the next
- Researchers using an MEG can identify the times at which various brain areas respond and thereby trace a wave of brain activity from its point of origin to the other areas that process it
Positron-emission tomography (PET)
- provides a high-resolution image of activity in a living brain by recording the emission of radioactivity from injected chemicals
- first, injection of glucose or some other chemical containing radioactive atoms
- tracking the levels of glucose tells us something about brain activity
- When radioactive atom decays, it releases a positron that immediately collides with a nearby electron, emitting two gamma rays in exactly opposite direction
- person’s head is surrounded by a set of gamma ray detectors
- When two detectors record gamma rays at the same time, they identify a spot halfway between those detectors as the point of origin of the gamma rays
- computer uses this information to determine how many gamma rays came from each spot in brain and therefore how much of the radioactive chemical is located in each area
- The areas with the most radioactivity are presumably the ones with the most active neurons.
functional magnetic resonance imaging (fMRI)
- modified version of MRI based on hemoglobin ( blood protein that binds oxygen) instead of water
- fMRI scanner is set to detect the amount of hemoglobin with oxygen because when a brain area gets more active, blood vessels dilate to allow more blood flow to the area and when the brain area uses oxygen, the percentage of hemoglobin with oxygen decreases. An fMRI scan responds to both of these processes
- but: does not tell as the cause of the activity
phrenology
- process of relating skull anatomy to behavior
- not useful because they are not related
computerized axial tomography (CT or CAT scan)
-dye is injected into the blood (to increase
contrast in the image) and then person’s head is placed into a CT scanner
-X-rays are passed through head and recorded by detectors on the opposite side. CT scanner is rotated slowly until a measurement has been taken at each angle over 180 degrees
- computer constructs images of the brain can be made
- often used for detecting tumors
magnetic resonance imaging (MRI)
- based on fact that any atom with an odd-numbered atomic weight, such as hydrogen, has an axis of rotation
- MRI device applies a powerful magnetic field to align all the axes of rotation, and then tilts them with a brief radio frequency field
- When radio frequency field is turned off, atomic nuclei release electromagnetic energy as they relax and return to their original axis
- By measuring that energy, MRI devices form an image of the brain
- MRI shows anatomical details smaller than a millimeter in diameter
