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Biopsych 215a Midterm 1


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Glia/Neurons: which is bigger/smaller?
Glia are about 1/10th the size of neurons - but they are also 10 times more numerous.
How many neurons & glial cells are there in the human nervous system?
about 100 billion
Function of dendrites?
Receive information from other neurons (or sensory receptors)
Function of axon hillock?
Processes information received by dendrites
Function of axon?
Carries information received by dendrites to other neurons (or muscles)
Neuron sending signal is efferent.
Neuron receiving signal is afferent.
Synaptic weight?
strength of synaptic connection (can change with learning)
Graceful degradation?
Even if a few neurons are damaged, the network can still produce the same representation, but the greater the damage, the greater the degradation of the representation.
Extracellular fluid?
Neuron sits in this
Intracellular fluid?
Neuron contains an intracellular fluid.
Electrical gradient?
Inner- and extra-cellular fluids have unequal # of ions. (more negative inside than out)
Polarized cell?
Negative ions inside cell; positive outside; creates a "potential"
What is a typical resting potential?
Resting potential?
When the neuron is polarized; the neuron is not doing anything special in this state.
Concentration gradient vs. electrical gradient?
A concentration gradient is the gradient of a substance relative to its own concentration; an electrical gradient is a gradient of positive/negative charges.
Is the cell resting during resting potential?
Resting potential is the cell's normal state (when it is not having an action potential), but, it takes energy to maintain the resting potential because of the sodium/potassium pumps at work.
IPSP (inhibitory postsynaptic potential)?
When the cell becomes even more polarized (hypopolarized) - more negative inside - in the region of the synapse.
Temporal summation?
If the same synapse is activated rapidly in succession, then the resulting changes in potential will add together.
Spatial summation?
If different synapses are activated at the same time, the resulting post-synaptic potentials can also summate.
Where does the net effect of all spatially and temporally summated EPSPs and IPSPs occur?
At the axon hillock.
What happens if the neuron's threshold of excitation is exceeded?
The nerve produces an action potential.
What happens during an action potential?
The membrane opens its sodium gates. This permits an explosive flow of sodium ions to cross the membrane, causing a massive depolarization of the cell membrane.
What happens during the refractory period?
The neuron becomes even more polarized than usual. Then, potassium gates open and allow potassium ions to follow their concentration gradient out of the cell. Also, there is no longer an electrical gradient to hold back the potassium. The neuron is now polarized, but there is still lots of sodium inside the cell (and too much potassium outside) - the opposite of what is normal. It takes a while for the sodium-potassium pump to clean things up.
Do dendrites and cell bodies have voltage-dependent gates?
No - they can produce graded potentials (EPSPs and IPSPs), but not action potentions - only the axon can do that.
Myelin Sheath?
An insulating material surrounding axon; speeds up conduction of nerve impulse.
Nodes of Ranvier?
At about 1mm intervals, these are breaks in the myelin sheath (the axon is exposed). The action potentials "jump" from one of these nodes to the next.
Saltatory Conduction?
The speeding-up of the nerve impulse by jumping from one node of Ranvier to the next.
How fast does saltatory conduction speed up the impulse?
Increases speed of propogation to about 100 m/s
What do excitatory signals do?
Cause sodium gates to open.
What do inhibitory signals do?
Open gates for potassium ions to leave the cell - or chlorid ions to enter the cell. This makes the cell more polarized (more negative inside)
How many dopamine receptor subtypes are there?
5. D1, D2, D3, D4, D5.
Receptor. Fast effects - immediately opens up gates in cell membrane for a particular ion.
Receptor. Slow effects - initiates a sequence of metabolic processes that in turn open up gates in the cell membrane for a particular ion. This sequence is mediated in part by second messengers, which carry information from the synapse to areas deeper within the cell.
Most abundant excitatory transmitter. Acts mainly on AMPA and NMDA receptors.
AMPA & NMDA Receptors?
Receptors mainly acted upon by glutamate, the most abundant excitatory transmitter.
The most abundant inhibitory transmitter; acts on GABA receptors.
Examples of other neurotransmitters?
Dopamine, norepinephrine, seratonin, acetylcholine.
What's the difference between neurotransmitters & hormones?
Hormones are released into the blood stream, not into the synaptic cleft. Their targets can be far away from the site of release.
Examples of hormones?
ACTH & cortisol - cortisol elevates blood sugar level and enhances metabolism (part of fight or flight response)
Brain orientation: Saggital?
Cross-section slice. Can be either medial or lateral (medial=in the middle, lateral=to the sides)
Brain orientation: Horizontal?
View from above.
Brain orientation: Coronal?
View from behind.
Brain orientation: Dorsal?
Brain orientation: Rostral/anterior?
Brain orientation: Caudal/posterior?
Brain orientation: Ventral?
"Triune Brain"?
Paul MacLean proposed a general organizing principle for understanding brain function - the brain can be understood in terms of its evolutionary history. 3 main parts, each reflecting a different stage of evolution.
What are the three parts of the "truine brain"?
1. The "reptilian part" consisting of the spinal cord and brain stem - the evolutionary oldest part, responsible for basic life functions; 2. the "neomamallian" part - consisting of the neocortex - the evolutionary newest part, responsible for higher cognitive functions; 3. the "paleomammalian" part - consisting of the limbic system - associated with an intermediate stage of evolution. Response for emotion, memory, and more.
"Reptillian" part of the brain?
part of triune brain theory - the spinal cord and brain stem. Evolutionarily the oldest part of the brain.
"Neomamallian" part of the brain?
Triune theory of the brain - evolutionarily the newest part of the brain. The neocortex. Responsible for higher cognitive functions.
"Paleomamallian" part of the brain?
Triune theory of the brain - evolutionarily intermediate stage. Limbic system. Responsible for emotion, memory, and more.
Longitudinal fissure?
Separates the brain into left and right hemispheres.
Each side of the brain (left and right) has some specific functions to that side - the left side of the brain controls the right side of the body, and vice versa.
Peripheral nervous system?
Portion of the nervous system outside the skull and spine.
Somatic nervous system?
Part of the PNS that interacts with the external environment. Affernt nerves carry sensory information from the skin, skeletal muscles, joints, eyes, ears, etc, to the CNS. Efferent nerves carry motor signals from the CNS to the skeletal muscles.
Autonomic nervous system?
Part of the PNS that regulates the internal environment. Afferent nerves carry sensory information from internal organs to the CNS. Efferent nerves carry motor signals from the CNS to the internal organs.
Sympathetic nervous system?
Excitement - fight or flight - increases heart rate, decreases digestion.
Parasympathetic nervous system?
Relaxation - decreases heart rate, increases digestion
How many spinal nerves are there?
What does gray matter consist of?
Cell bodies and dendrites
What does white matter consist of?
Myelin that surrounds axons.
Ventral column - carries motor info in which direction (to or from) brain?
Carries it away from brain
Dorsal column - carries sensory info in which direction (to or from) the brain?
Carries it to the brain.
Marks the transition from brainstem to spinal cord. Is involved in vital bodily functions, eg breathing and heart rate. Lesions of the medulla are often fatal.
A fiber tract (a neural pathway) that mainly carries information to and from the cerebellum.
Where do many sensory and motor axons cross from one side of the brain to the other?
At the medulla and pons.
What does the cerebellum do?
Involved in motor control and motor learning.
Where is the cerebellum located?
A large structure that sits at the base of the brain. Attached to the brain stem via the pons, but is not technically part of the brain stem.
Reticular formation? Raphe system? Locus coeruleus?
Groups of nuclei that project widely through the brain (their axons travel long distances)
Reticular formation?
Releases acetylcholine - increases arousal, attention, wakefulness (lesions cause sleep; damage can cause a coma..)
Raphe System?
Releases seratonin - low seratonin = more aggression. May be involved in monitoring appropriateness of behaviour.
Locus Coeruleus?
Releases norepenephrine - bursts of arousal, eg when making a sudden response.
What makes up the hindbrain?
The medulla, pons, cerebellum, and internal nuclei.
"Roof" - part of the midbrain - includes the superior and inferior colliculus, important routes for sensory information.
Superior colliculus?
Involved in visual attention.
Inferior colliculus?
Involved in audition.
Part of the midbrain - the "floor" - includes the substantia nigra and ventral tegmental area.
Substantia Nigra & Ventral tegmental area?
These nuclei project widely (axons project throughout brain). They release dopamine - they are important for movement and learning (dopamine deficiency causes trouble with movement in Parkinsons).
Cranial nerves?
Control sensation and muscle movement to the head.
Optic nerve?
Connects to the eyes, and carries visual information.
Pineal gland?
Sits at front of thalamus (looks like a clitoris). Releases melatonin.
The center of the forebrain - relay station for sensory information to/from the cerebral cortex (except olfactory).
Limbic system?
Involved in emotions and memory. Part of the forebrain - consists of a set of (mainly) subcortical structures that form a border (or limbus) around the brain stem.
Olfactory bulbs?
Process smell (olfaction).
Involved in emotion, particularly fear - and memory. Part of the limbic system.
Involved with drives (like sex drive, etc) - damage here affects sexual behaviour, temperature regulation, fighting, feeding, activity level. Part of the limbic system.
Part of the memory circuit. Takes info from hippocampus. Also part of the limbic system.
Looks like a seahorse. Involved in episodic memory.
Anterior cingulate cortex?
Transforms emotions into actions.
List the parts of the limbic system.
Amygdala, hippocampus, cingulate cortex, fornix, septum, and mammillary body.
Basal Ganglia?
Collection of nuclei that include the caudate nucleus, putamen, and globus pallidus. These structures are involved mainly in motor control, but are also involved in learning and higher cognitive function.
Nucleus accumbens?
Involved in processing rewards. Sometimes considered part of the limbic system, sometimes considered part of the basal ganglia.
Cerebral cortex?
Involved in higher cognitive function. The convoluted surface on the outside of the brain. Also part of the forebrain.
Blood brain barrier?
Although blood vessels carry nutrients and oxygen to the brain, the blood is separated from the brain (and cerebral spinal fluid) by a blood-brain barrier. The barrier lets across good things, like oxygen, but blocks bad things, like viruses.
The brain is protected by the skull and by the meninges - three layers.
What are the three layers of the meninges?
Dura mater (tough outer membrane); arachnoid membrane (porous membrane under the dura mater); pia mater (delicate inner membrane).
Subarachoid space?
Space beneath arachnoid membrane - contains blood vessels and cerebral spinal fluid.
Cavities filled with cerebral-spinal fluid. There are 4.
Cerebral spinal fluid?
Fills space between brain and meninges, and fills ventricles. Cushions brain against shock and sudden movements.
"Ridge" on cerebral cortex.
"Groove" on cerebral cortex.
Large fissure on cerebral cortex (like between hemispheres)
Occipital lobe?
Back of the head. Involved in vision.
Primary Visual cortex?
AKA Striate cortex. Part of the occipital lobe. Visual cortex is involved in elementary aspects of visual processing, such as identifying features (lines, spots, etc) of the environment.
Extrastriate cortex?
Part of the occipital lobe - involved in higher aspects of visual processing.
Parietal lobe?
Top middle of brain. Involved in determining where objects are located in space. Involved in spatial attention. Involved in transforming sensory information into action, for example, how to reach for an object.
People with damage to right parietal cortex, for example, neglect the left part of space - they may fail to eat food on the left side of the plate, etc.
Temporal lobe?
Sides of brain. Higher level vision; object categorization. Auditory cortex. Language comprehension (left hemisphere).
Impaired ability to recognize or identify faces. Results from damage to the ventral-medial aspect of the temporal lobe, in an area called the fusiform gyrus.
Fusiform gyrus?
An area of the brain which appears to specialize in face recognition. Damage in this area results in prosopagnosia, the impaired ability to recognize or identify faces.
Frontal Lobe?
Nearly half the cortex. Posterior parts involved in motor control. The Anterior part is the prefrontal cortex.
Prefrontal cortex?
Involved in executive control - high level plans and decision making.
Orbitofrontal damage?
Damage to a part of the prefrontal cortex called the oribotofrontal cortex (located behind the eyes). Phineas Gage - causes disinhibited and socially inappropriate behaviour, and the inability to forgo short-term rewards with longterm gain.
Central sulcus?
Frontal and parietal lobes are separated by the central sulcus, a deep cortical fissure.
Precentral gyrus?
AKA primary motor cortex - anterior to the central sulcus. Specialized for fine movements, and is characterized by a somatotopic map that controls different parts of the body.
Postcentral gyrus?
Posterior to the central sulcus. AKA primary somatosensory cortex. Processes touch sensations and proprioceptive information (information from joints & muscles). Characterized by a somatotopic map that receives information from different parts of the body.
Cingulate cortex?
Stretches along inner surfaces of the hemispheres. Little agreement on what it does.
Posterior cingulate cortex?
Involved in memory.
What is a specialization of the left hemisphere?
What is a specialization of the right hemisphere?
Emotional expression, spatial relationships, and gestalt (perceiving overall patterns)
Corpus callosum?
Large fiber tract connecting the hemispheres. Carries information between cortex in each hemisphere.

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