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Describe drug craving and withdrawal. What are
the neural substrates associated with each?
- Craving= enhanced transmission in the
- mesocorticalimbic dopamine system during drug use.
What are the roles of dopamine, acetylcholine and
serotonin in addiction?
- Dopamine and Seritonin= produce drug hunger and
- real hunger.
-Dopamine= primary fuel for addiction
- -Acetylocholine= Addition is a potential role of
- acetylocholine, conditioned, learned, reward…
How are the nucleus accumbens and orbitofrontal
cortex involved in addiction?
- They both establish addiction
How is dopamine and the reward pathway involved
in learning, and how does this affect addiction?
- dopamine activity from drugs make learning difficult.
- -Dopamine is
- released when reward pathway is stimulated.
Name the lobes of the brain, indicate where they
are located and discuss their functions?
Frontal Lobe- Motor, speech and thought process.
- Parietal Lobe- Cognition, Information processing,
- pain and touch (somata sensory).
Occipital Lobe- Vision
Temporal Lobe- Auditory, memory and learning.
Describe the major subdivisions of the forebrain?
List major structures found in each and give their functions.
- cortex and lobes, (sub cortical) Limbic system, Basal Ganglia, thalamus,
- Hypothalamus (the forebrain is broken down into 2 sections)
- -Telencephalon =
- Cerebral Cortex, Basal Ganglia and Limbic System= organization and planning,
- motor, learning memory.
- -Diencephalon =
- Thalamus and Hypothalamus.= eating, drinking, sex, biorhythms and temperature
Describe how the major divisions of the brain
arise from the neural tube.
- First neural plate folds, curls over to make
- forebrain, midbrain, and hindbrain.
How is visual information transduced?
- -Absorption of light causes rhodopsin
- to break into opsin and retinal.
-Enzymes break down cyclic GMP.
-Fewer sodium channels remain open.
- -Cell hyperpolarizes in light (it’s
- depolarized in the dark).
- -Photoreceptors produce graded
- -Photopigments are located in the
- membrane of the outer segment of rods and cones
- -Each pigment consists of an opsin
- (a protein) and retinal (a lipid)
- -In the dark, membrane NA+
- channels are open -> glutamate is released which depolarizes the membrane
- -Light splits the opsin and retinal
- -Activates transducin (G
- -Reduces cGMP -> closes NA+
- -The net effect of light is to hyperpolarize the retinal
- receptor and reduce the release of glutamate.
Describe the primary visual pathway and the
secondary extrastriatal pathways.
- pathway- Tectum – back to aliarybody (pupil control) to hypothamamus, then to
Provide an example of how the sensory systems
process information in both a serial and parallel fashion.
- - Parallel processing- two eyes to see depth
- perception in the world. The two eyes provide two visual streams. Appear to be
- independent streams of information about light and dark. Ganglion cells of both
- ON and OFF have different tyes of receptive fields.
- Strong desire to consume a drug accompanied by diminishing capacity to
- limit the intake of the drug. (SLIDES- Drug addiction is conceptualized
- as a chronic relapsing syndrome that moves from an impulse control disorder
- involving positive reinforcement to a compulsive disorder involving negative
- Vast array of variables, sometimes difficult to tease apart, typically
- associated with drug addiction, including one’s predisposition to consume
- drugs, the development of tolerance to a drug, withdrawal symptoms on the
- removal of a drug, craving for a drug, and the likelihood of relapse after
- ceasing consumption of a drug.
- Defining feature of drug addiction in which the individual becomes
- increasingly less sensitive to the drug, requires higher doses to obtain the
- initial effect of the drug.
- Defining feature of drug addiction in which the individual experiences
- either physiological or psychological symptoms after ceasing the consumption of
- a particular drug.
- Cessation of an aversive stimulus on the presentation of a particular
- response. Relapse into drug use is reinforced because it reduces the negative
- experience of withdrawal.
- Development of tolerance and withdrawal following chronic use of a drug;
- physical and psychological problems arise upon cessation of drug use.
Vental tegmental area (VTA
- Cluster of cell bodies in the midbrain that synthesize dopamine; extends
- to the nucleus accumbens and is involved with reward circuits of the brain.
Orbitofrontal Cortex (OFC)
- plays an important role in aquiring an addiction, there is more than the
- simple pleasure. Caused the rats to keep pushing the lever for cocaine.
- Stimulation to the brain lever.
- Brain structures continuous with and sharing morphological similarities
- with the amygdaloid nuclei, including the nucleus accumbens, BNST, and olfactory
- -Also works with hippocampus, prefrontal cortex
- to send projections to the nucleus accumbens.
Medial forebrain bundle
- Large collection of axons that extend from the hypothalamus to the
- septum, a structure in the limbic system. Animals respond continuously to
- receiving electrical brain stimulation in this area; consequently, it is
- considered the most prevalent brain reward system of the nervous system.
- Neurochemical technique in which the level of a neurotransmitter from a
- particular area of the brain is assessed. This technique is unique because the
- researcher can extract the neurotransmitter while the animal is engaging in a
- particular behavior.
- The rat get injections in one certain place, There is another place
- available to the rat when it is drug free. If it prefers the same compartment
- as when it was injected is it place pereference. Rats do this.
- (Mesolimbic dopamine pathway)- Neurons extending from the midbrain to
- the forebrain produce and release dopamine into the forebrain. Two pathways
- make up this system: (1) the mesocorticolimbic (reward circuit) system extends from the ventral tegmental
- area to the nucleus accumbens; (2) the nigrostriatal pathway, involved in
- neuromuscular functions, extends from the substantia nigra to the corpus
Persistent, intense desire to consume a drug.
- An examination of behavior
- in animals or humans whose cerebral hemispheres have been disconnected by
- cutting the corpus callosum.
- A movement disorder caused by
- damage to the substantia nigra, characterized by paucity of movement,
- difficulty in initiating willed movement, and resting tremor.
- - A result of the depletion of
- cerebral dopamine.
- A cell group in the
- midbrain that uses dopamine as a neurotransmitter and innervates the striatum.
- Naked big handed and lipped
- located in the
- metencephalon that participates in balance, muscle tone, muscle coordination,
- some types of learning, and possibly higher cognitive functions in humans.
- Collection of nuclei within
- the cerebral hemispheres that participates in the control of movement.
- forebrain structures that
- participate in emotional behavior and learning.
- Three membranes that cover
- the surface of the central nervous system and the peripheral nerves.
Planes of dissection
- Sagittal plane- Left from right Coronal (or
- transverse) plane- Front from back. Horizontal
- plane- Top from Bottom.
- The cerebrospinal fluid-
- filled spaces inside the brain, consisting of the lateral ventricles, third
- ventricle, cerebral aqueduct, and fourth ventricle.
Swelling of ventricles in babies
- - Serious issue for adults
- because skull can not expland.
Differentiation of the Forebrain
- Secondary vesicles: Optic
- and telencephalon and Diencephalon (between brain)
- Results from failure of the
- anterior and posterior ends of the tubes to close.
- Results from failure of the
- neural tube to close.
Secondary vesicles of forebrain
Optic and telencephalon
Midbrain structure and function
- Passes information from the
- spinal cord to the forebrain, contribute to sensory systems, control of
- movement, pain mood and pleasure.
Differentiation of Hindbrain
- Cerebellum- tissue along dorsal
- lateral side or rostril hindbrain until it fuses with other side.
- -PONS- ventral wall, swells to
- form PONS.
- -Medulla Oblongata – walls of
- caudal portion of hindbrain swells.
- 4th ventricle-
- residual central ventricle in hindbrain.
- The cerebral cortex, with
- six or more layers of neurons, found only in mammals.
Primary cortical areas
- – Primary motor cortex- An area of the cortex in the frontal lobe that
- provides the highest level of processing for body senses such as touch,
- position, temperature and pain. Primary visual cortex- an area of the sensory
- cortex in the occipital lobe that provides the initial cortical processing of
- visual information.
- The sulcus in the cerebrum
- that divides the frontal lobe from the parietal lobe.
- Separates Temporal and
- frontal lobes.
Primary motor cortex
- Brodmann’s area 4, located
- on the precentral gyrus; the region of cortex that, when weakly stimulated,
- elicits localized signals at the body’s sensory surfaces.
Primary Somatosensory cortical areas-
- Brodmann’s area 3b located
- in the postcentral gyrus, also called S1.
Longitudinal cerebral fissure
- The large separation of the
- hemispheres, (right down the corpus collosum.
- The inability to recognize
- objects, even though simple sensory skills appear to be noral: most commonly
- caused by damage to posterior parietal areas of the brain.
Neurons of retina
120 million rods
-6 million cones
- Visual pigment found in
- retina, altered by light.
- The pit or depression in
- the retina at the center of the macula; in humans, the fovea contains only cone
- photoreceptors ad is specialized for high-acuity vision.
- The location on the retina where
- optic nerve axons leave the eye.
Accomodation by the lens
- The focusing of light by changing the shape of the eye’s lens.
Trichromatic theory of color vision
- color vision reacts from 3
- different receptors.
Opponent process theory of color vision
- Color vision is based on
- red-green and blue-yellow opposition.
LGN (Lateral Geniculate Nucleus)-
- A thalamic nucleus that
- relays information from the retina to the primary visual cortex.
- The topographic
- organization of visual pathways in which neighboring cells on the retina send
- information to neighboring cells in a target structure.
- The half of the visual
- field to one side of the fixation point.
binocular visual field
- The portion of the visual
- field viewed by both eyes.
- A term used to describe the
- superior colliculus, particularly in nonmammalian vertebrates.
- A structure in the tectum
- of the midbrain that receives direct retinal input and controls saccadic eye
M, P, non-M and P cells
- A collection of cells,
- mainl in primary visual cortical layers II & III, characterized by a high
- level of the enzyme cytochrome oxidase.
koniocellular (LGN) layer
- A layer of the lateral
- geniculate nucleus containing very small clles, lying just ventral to each
- magnocellular and pavocellular layer.
- The unit of cerebral cortex
- that is necessary and sufficient to analyze one discrete point in a sensory
primary visual cortex
- Brodmann’s area 3b located at the
- pole of the occipital lobe’ also called striate cortex and V1.
-4th Layer, Primary layer for input.
- Primary visual cortex,
- Brodmann’s area 17; also called V1.
- The region of a sensory
- surface (retina, skin) that, when stimulated, changes the membrane potential of
- a neuron.
- Optic nerve, no sensory
- area in the retina where the nerve is.