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155 Cards in this Set

  • Front
  • Back
La majeure partie des systèmes nerveux est organisée en trois composantes:
•Détecteur afférent, intégration et l’action efférente
Les cnidaires sont une exception - pourquoi?
•Leur système nerveux est un réseau interrelié(une toile nerveuse)
•Les neurones ne sont pas spécialisés
•Les neurones peuvent transporter leur potentiel d’action dans les deux sens (pas d’afférent et d’efférent)
•Cette organisation permet tout de même des comportements complexes
•Symétrie bilatérale:
Côtés droit et gauche forment une image miroir
•Céphalisation:
Les organes sensoriels se concentrent à la partie avant de l’animal
•Ganglion:
Groupes de corps cellulaires neuronaux
•Noyau:
Groupes de corps cellulaires neuronaux dans le cerveau
•Cerveau:
Centre d’intégration regroupant plusieurs noyaux
•Voie:
Groupe d’axones à l’intérieur du système nerveux central (SNC)
•Nerf:
Groupe d’axones à l’extérieur du SNC
•Endonèrve:
Entoure chaque axone
•Périnèrve:
Entoure un faisceau (fascicule) d’axones
•Épinèrve:
Entoure le nerf entier
Nerf mixte:
Contiens des neurones afférents et efférents
•Les _______ et les _________ ne présentent pas de céphalisation
Les cnidaires et les échinodermes
Les animaux au système nerveux plus complexe ont moins de neurones, donc moins de synapses - V/F?
Faux
Les animaux au système nerveux plus complexe ont plus de neurones, donc plus de synapses
In the invertebrates, bundles of axons that connect ganglia or run between a ganglion and he brain are called what
CONNECTIVES or COMMISSURES
The total number of neurons is not necessarily larger in species with more complex integrating centers. - T/F
TRUE Ex. some flatworms have several thousand neurons, despite lacking an obvious brain.
Est-ce que les cnidaires (méduse) a un centre d'integration principale?
NON
Describe the neural architecture of a flatworm (planaire)
Architchture varies between groups - this one has two nervous cords

Flatworms are the simplest of the bilaterally symmetrical animals. Some species lack an obvious brain whereas others have a brain so well developed, the flatworm can perform complex behaviours.
Describe the neural architecture of an annelid (round worm/ver de terre)
More structured nervous system than flatworms:
- well-developed brain
- ganglia in each body segment
- one or more nerve cords that communicate information between the tissues and the various integrating centres.
Describe the neural architecture of an arthropod (crab)
Cerveau centrale
Une corde nerveuse principale
ganglion thoracique principale

Arthropods:
- ventral nerve cord
- brain
- a large ganglion within each body segment
Describe the neural architecture of molluscs (patelle)
Des ganglions sont regroupes - les centres d'integrations = former une cerveau (ensemble des centres d'intergrations regroupes)

patelle - petit mollusc - un font de cone (comme un chapeau)

Most species have
- dual nerve cords
- series of large ganglia
- cerebral ganglia (innervate head and neck)
- buccal ganglia (innervate mouth and stomach)
Describe the neural architecture of Cephalopod molluscs (calmar/squid)
Ganglion ici est pour le periphery
Le controle de pattes est pris en charge par les ganglions et PAS par le cerveau

This group includes octopus and squid
The anterior pairs of ganglia are greatly expanded and placed close together to create a tightly packed mass that lies between the eyes and encircles the esophagus - in other words, a large and complex brain.

Octopus have brains that are much larger relative to its body size, which suggests substantial intelligence (can navigate mazes, mimic other octopi, etc.)
- Each arm has a large ganglion that controls arm movements and that can function essentially independently of the brain. Thus, the integrating center of an octopus is actually highly distributed and involves both the brain and the ganglia.
Describe the neural architecture of Echinoderms (starfish)
Le geometrie est radial *exception aussi
Cephalisation = on va avoir les gangilions

Radial symmetry + lack an obvious brain.
Have a series of ganglia and a series of nerve rings
These echinoderms have most likely descended from a bilaterally symmetrical ancestor that likely had some cephalization.
Describe the neural architecture of Chordé/chordate (alligator)
Les ganglions dans tout le long de la moelle epiniere) comme les humaines
What is the difference between invertebrates and vertebrates in terms of spinal cords?
Vertebrates, being one of the most highly cephalized organisms, have a hollow dorsal nerve cord, rather than a solid ventral nerve cord (invertebrates).
What do the cervical nerves innervate?
Innervate the head, neck, arms, hands, and diaphragm
What do the thoracic nerves innervate?
Les muscles intercostaux
la region du ventre (chest)
Heart
Nerfs lombaires + sacrés, coccygien: - what do they innervate?
Nerfs lombaires + sacrés, coccygien:
Les parties inferior et vicaires
legs, pelvis, bladder, and bowel
How many cranial nerves are there?
13
What is contained in grey matter?
Gray matter: neuronal cell bodies and dendrites
What is contained in white matter?
White matter: bundles of axons and myelin sheaths
Is the white matter inside our outside for the spinal cord?
Moelle épinière
•Matière blanche à l’extérieur et grise à l’intérieur
Is the white matter inside our outside for the brain?
Cerveau
•Matière grise à l’extérieur et blanche à l’intérieur
•Méninges:
•Le nombre de couches varie en fonction du groupe animal: __ couche chez les poisson et __ chez les mammifères
Couches de tissu conjonctif entourant le cerveau et la moelle épinière
1 - poisson
3 - mammifères
2 - amphibians, reptiles and birds
Liquide cérébro-spinal (LCS)
•Remplis l’espace du SNC et agit comme amortisseur
Protects against shock
Cushions the delicate tissues of the CNS
Barrière hémato-encéphalique
•Jonctions serrées de l’endothélium des capillaires du cerveau limitent le passage des solutés du sang vers le LCS

protege le CNS contre des molecules (principalement)
les vessaux endothelial est tres dur (c'est difficle de transferer les molecules a travers le barrier)
liposoluble et petit = les molcules qui est capable de trsporter a travers le barrier

Blood-brain barrier:
- tight junctions between the endothelial cells lining the brain capillaries. = prevents materials from leaking out of the bloodstream and into the CNS via paracellular pathways (between the cells)
- NO pinocytosis
- small, lipid soluble molecules (ethanol and some barbiturate drugs) can diffuse across the barrier directly
- Specialized carrier transport systems allow the brain to take up circulating nutrients such as glucose and aa.
- More permeable: pineal gland, pituitary gland, parts of the hypothalamus (allows hormones to leave the brain and enter the circulatory system).
What are the names of the three meninges surrounding the brain?
Just before which layer is the epidural injected into?
Dura mater
Arachnoid
Pia mater

Just outside the third tissue layer (or dura mater) lies the epidural space, where the epidural is inserted.
What are the three principle regions of the vertebrate brain?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Prosencephalon (forebrain) - what does it control? What are the brain sections that it forms (fully developed brain)?
•Intègre l’olfaction avec les autres sens
•Régulation de la température, reproduction, alimentation, émotion
•Mémoire et apprentissage chez les mammifères

Cerebral cortex
(olfactory bulb)
Thalamus
(hypothalamus, hypophyse)
Mesencephalon (midbrain)
What are the brain sections that it forms (fully developed brain)?
- coordinating visual, auditory and sensory info from touch and pressure receptors (in mammals it is more of a routing centre than an integration centre per se)

Coordinating sensory information

NONE - brain sections
Rhombencephalon (hindbrain)
What are the brain sections that it forms (fully developed brain)?
Involuntary reflexes and actions
Ex. Breathing and body position maintenance

Pons
Cerebellum
Medulla oblongata
Which part of the brain is relatively large for both BIRDS and MAMMALS
forebrain
Birds have a thin and undeveloped cortex. - t/f
True
What is the difference between the organization of white matter and grey matter of the brain between mammals and vertebrates?
Mammals: White matter = INSIDE, Grey matter = OUTSIDE
- Isocortex for mammals
- Presence of Basal nuclei = clusters of gray matter deep within the brain.

Vertebrates: White matter = OUTSIDE, Grey matter = INSIDE
Which two organisms have a relatively large midbrain and cerebellum? Why?
BONY FISHES and BIRDS have a relatively large midbrain and cerebellum - involved in interpretation of sensory signals and coordinating motion. These creatures move in a three dimensional environment (whereas terrestrial creatures only move along the ground), therefore they need to interpret complex sensory information and coordinate their body accordingly.
•Le cerveau des ______ et des ______ est plus gros que les autres vertébrés
des mammifères + des oiseaux
Brain size tends to increase with body size - t/f
True
Cerveau postérieur
•Trois régions
(1) Medulla oblongata
(2) Pons
(3) Cerebellum
Medulla oblongata - what does it do? Where is it located?
Adjacent to the spinal cord

Regulates:
- Respiration
- Cardiac rhythm
- Blood pressure
- Blood vessels (contraction and dilation)

Pathway between the spinal cord and the brain

Crossing of the axons controlling the opposite sides of the brain occurs at this point.

Damage at this point, is almost always fatal.
Pons - what does it do?
- Between the medulla and the cerebellum
- Alertness, initiates states of sleep and dreaming

Centres de regulation - controls the respiration rhythm, by influencing activity of the medulla oblongata

- aka "bridge" - impt pathway that communicates information between the medulla, the cerebellum and the forebrain.
Cerebellum - what does it do?
- 2 hemispheres at the base of the brain
- Motor coordination (locomotion), maintains body posture, integrates information from proprioceptors
- Damage here = cerebral palsy
Le cerveau moyen = Centre primaire de coordination et initiation de réponses comportementales chez les (2) ?
les poissons et amphibiens
Chez les mammifères la taille et les fonctions sont réduites - c'est quoi la function primaire pour le cerveau moyen pour les mammifères?
•Sert surtout de relai entre le cerveau antérieur et la moelle épinière
•Parfois le cerveau moyen est groupé avec _____ et ___________ et nommé tronc cérébral (brainstem)
le pont
le bulbe rachidien
- _______ (midbrain) helps with fine muscle control (reflex responses to visual, auditory, and touch information). If lesions are present =
Tegmentum
Parkinsons disease
Roof of midbrain =, which contain optic lobes (coordinate sensory input from the eyes).
tectum
Cerveau antérieur - what is its main job?
•Régions principales (4)
•Impliqué dans le traitement et l’intégration de
l’information sensorielle et coordonner les comportements

•Cerebrum
•Épithalamus
•Thalamus
•Hypothalamus
What coordinates the two hemispheres, the two homologous regions of the brain -
corpus callosum
Are the two hemispheres of the brain identical functionally?
The two hemispheres are not functionally identical.
Left controls speech whereas right controls perception of spatial relationships.
The corpus callosum allows the two hemispheres to work with each other and communicate.
Hypothalamus - where is it located and what is its primary role?
Situé à la base du cerveau antérieur (sous le thalamus)

•Important pour le maintien de plusieurs fonctions
homéostatique

•Température corporelle, pression sanguine, équilibre
hydrique, faim, soif, reproduction, plaisir

•Interagis avec le système nerveux autonome

•Régule la sécrétion d’hormones de l’hypophyse (pituitary)
Système limbique AKA _________ affecte quoi?
What are the four parts?
cerveau émotionnel
Affecte les émotions, la motivation et la mémoire

Hypothalamus
Amigdala
Hippocampus
Olfactory bulb
Amigdala - what does it do?
contrôle l’agression et la réaction de peur

a lesion in the area of the amygdala can affect the social interaction one can have, not capable of reading the signals of aggression others may portray
Hippocampus - what does it do?
Convertis la mémoire à court terme en
mémoire à long terme

Damage = prevention from creating and storing long term memories
Olfactory bulb - what does it do?
Sense of smell

Can revive previous associations and memories with specific smells/scents
- olfactory information bypasses the thalamus (where all other sensory info is first processed) and takes a more direct route to the olfactory bulb.
- the olfactory bulb is also connected to the amygdala and hippocampus, and thus odours tend to provoke strong emotions and memories in humans.
Is the thalamus made of grey matter or white matter? Where is it located?

What does it do?
Grey matter
Above the hypothalamus

Physical link/pathway in the cerebral trunk (relays information to the cortex)
Receives information from the limbic system and olfactory senses
What is the reticular formation?
The reticular formation is a net of neurons extending from the thalamus down through the brainstem, including parts of the midbrain, pons, and medulla oblongata.

The reticular formation acts as a filter for incoming sensory information.
Epithalamus - where is it located and what does it do?
Above the thalamus
Melatonin secretion (pineal gland) - circadian rhythms, regulation of hunger and thirst
What does the cortex do?
Concentration
Reasoning
Abstract thought

Integrates sensorial information and voluntary movement
What is the difference between a gyrus and a sulcus?
What is their purpose?
Gyrus = fold, sulcus = groove

These folds greatly increase the surface area of the cortex, increasing the number of neurons and their interconnections, and thus increasing the functional complexity of the forebrain. Therefore the degree of folding appears to be correlated with the functional complexity of the brain and the intelligence of the organism.
Couches du cortex - combien?
Nommé également ______ chez les mammifères
Diffèrent selon la _______ et la _____ des neurones
•Six couches distinctes chez les mammifères
néocortex (isocortex)
la densité et la forme
•Nombre de connexions variables selon les couches
Frontal lobe:
reasoning, planning, some aspects of speech
Parietal lobe:
movement, orientation, recognition, and perception of stimuli
Occipital lobe:
visual processing
Temporal lobe:
perception and recognition of auditory stimuli, memory, and speech
What is Topography?
he specific areas of the cortex correspond to particular functions
Ex. Somatosensory cortex and the primary motor cortex

These regions can be disproportionate.
Draw out the pathway that a incoming stimulus would take when travelling to the brain and then back to the muscles. Label the PNS and CNS, as well as the afferent, interneuron and efferent neurons.
Slide 1 - PDF #1
Les interneurones permettent _________?
L’intégration
Divisions du système nerveux périphérique - Dessinez les branches divisées qui viennent de la système nerveux périphérique.
Slide 36 (PDF #3)
Qu'est-ce que les trois branches du système nerveux autonome?
Sympathique
Parasympathique
Entérique
Divisions du système nerveux périphérique système nerveux autonome est essentiel au maintien de quoi?
l'homéostasie
Branche du système nerveux autonome: sympathique
- Le plus actif quand?
- Réguler quoi?
•Le plus actif lors de période de stress ou l’activité physique
•Régule la réponse de fuite

Fight or flight response - recruite les voie sympateques le plus

Organes cibles:
- Rhythme cardiac est controle/regule par la reponse de fuite.
- Toutes les machineries pour l'action de respiration.
- Systeme digestif (constrictions des vaseux du system digestif)
- Liberation de l'adrenaline (la glande surrenale)
Branche du système nerveux autonome: parasympathique
- Le plus actif quand?
- Réguler quoi?
•Le plus actif lors du repos
•Régule la période de repos et digestion
Branche du système nerveux autonome: entérique
- Le plus actif quand?
- Réguler quoi?
•Indépendant des deux autres branches
•Innerve les organes du canal alimentaire
•Équilibre entre le système nerveux sympathique et parasympathique - c'est quoi le mot qui décris ceci?
l'homéostasie
Trois mécanismes régulant les fonctions autonomes - qu'est-ce que c'est?
•Double innervation
•Action antagoniste
•Tonus de base
38Double
•Double innervation
•La plupart des organes sont innervés par les deux systèmes
•Action antagoniste
•Un système stimule et l’autre inhibe
•Tonus de base
•En condition de repos (de base) les neurones autonomes envoi des potentiels d’actions

Thus, both increases and decreases in action potential frequency can alter the response of the target organ, similar to volume control on a radio.
Les recepteurs adrenergic sont liee avec le systeme ________.
SYMPATHETIQUE
List the effector organs that ONLY have ALPHA adrenergic receptors
- Pupil of the eye
- Arterioles
- Exocrine and endocrine pancreas
- Sweat glands
- Arrector pili muscles of the skin
- Male sex organs
List the effector organs that ONLY have BETA adrenergic receptors
- Heart
- Bronchioles of the lungs
- Kidney
- Adipose tissue
List the effector organs that have BOTH ALPHA and BETA adrenergic receptors
- Salivary glands
- Digestive tract
- Bladder
- Urethra
Stronger affinity:
Alpha = which NT(s)?
Beta = which NT(s)?
Stronger affinity:
Alpha = noradrenaline
Beta = both adrenaline and noradrenaline
Similarités des voies des systèmes autonomes (2)?
•Ces voies contiennent deux neurones en série
•Les neurones pré et postganglionnaires font synapse au niveau de ganglion autonome
Decris la difference entre le Préganglionnaire et le Postganglionnaire.
•Préganglionnaire
•Peut former des synapses avec plusieurs neurones postganglionnaires et neurones intrinsèques

•Postganglionnaire
•Libère les neurotransmetteurs à l’organe effecteur par des varicosités
What are intrinsic neurons?
- intrinsic neurons: located inside the ganglion, which allows for relatively complex integration of function within the ganglion itself.
T/F - One preganglion usu synapses with more than one/several post ganglion
True
Différences des voies des systèmes autonomes - il y a trois! What are the differences between the S and PS systems for each of these three differences.
•Localisation des corps cellulaires préganglionnaires
•Sympathique (S): Régions thoracique et lombaire de la moelle épinière
•Parasympathique (PS): Cerveau postérieur et région sacrée de la moelle épinière

•Localisation des ganglions
•S: Chaine près de la moelle épinière
•PS: Près des organes effecteurs

•Nombre de neurones postganglionnaire formant des synapses avec un seul neurone préganglionnaire
•S: 10 ou plus
•PS: 3 ou moins
What is the difference between the stimulation of a preganglionic sympathetic neuron and the stimulation of a preganglionic parasymthetic?
Stimulation of a single sympathetic preganglionic neuron will thus have rather WIDESPREAD effects, while stimulation of a preganglionic parasympathetic neuron typically causes a much more LOCALIZED response.
Describe the structure of the pre and post ganglionic neuron for the PS system
- what NT is released at the preganglionic terminals, and what receptor does it act on?
- what NT is released at the post-ganglionic terminals, and what receptor does it act on?
- long pregang - NT: ACh --> Cholinergic Nicotinic receptor
- short post gang - NT: ACh ---> Cholinergic muscarinic receptor
Describe the structure of the pre and post ganglionic neuron for the S system
- what NT is released at the preganglionic terminals
- what NT is released at the post-ganglionic terminals
- Short pregang -NT: ACh --> cholinergic Nicotinic receptor
- Long postgang - NT: NE --> Adrenergic receptor
What type of receptor is a muscarinic receptor?
Muscarinic receptors are G-protein coupled receptors - typically they cause a much slower response than nicotinic Ach receptors
What type of receptor is a nicotinic cholinergic receptor?
The effects of nicotinic receptors are always stimulatory.
- they are ligand-gated ion channels, therefore binding Ach allows an influx of Na+ into the cell for depolarization
Generally what kind of effects are seen from:
- alpha receptors: _____
- beta receptors: ______
Generally:
- alpha receptors: stimulatory
- beta receptors: inhibitory
What is special about adrenergic receptor?
NE binds to alpha or beta adrenergic receptors which work through different second messenger pathways and cause a variety of responses in the target cell.

Be aware that there are some postsynaptic sympathetic neurons that release Ach instead of NE (ie. sweat glands of the skin) but these neurons are much less numerous than the adrenergic neurons.
•Certains organes effecteurs reçoivent seulement une innervation sympathique - nommez les 5 organes qui sont inclues.
•Médullosurrénale (Adrenal medulla)
•Amas de neurones postganglionnaires modifiés
•Glandes sudoripares (sweat glands)
•Muscles horripilateurs (Arrector pili muscles of the skin)
•Reins
•La plupart des vaisseaux sanguins
Do bony fish have an adrenal medulla? What about sharks and rays?
No

Bony fish do not have an adrenal medulla, they have the adrenal-like cells dispersed throughout the anterior part of the kidney, similar to the location in mammals.

In sharks and rays, these neurosecretory cells are associated with the autonomic ganglia.
What happens when the adrenal medulla is stimulated? Which cells secrete the NT that will then travel to the effector organs?
Adrenal medulla (core of the adrenal gland)- a highly modified sympatheic ganglion

When preganglionic sympathic neurons terminate in the adrenal medulla, there are no post-gagnlionic neurons to reach an effector organ. RATHER, there is modification of neurosecretory cells called CHROMAFFIN CELLS that release E and NE directly into the circulation, producing widespread excitatory effects.
Discute la régulation du système nerveux autonome - dessinez une image (flow chart)
Slide 47 - PDF#3
Which organ initiates fight or flight response, which involves widespread activation of sympathetic neurons
Hypothalamus
Where is the reticular formation found?
The thalamus
What effects does the limbic system have on the ANS?
Limbic system also affects the ANS
- blushing
- fainting at the sight of blood
- 'butterflies'
= responses of the ANS to emotions
Describe what happens in the ANS when the blood pressure drops. Draw a flow chart to illustrate your ideas.
Slide 48 - PDF#3
What are the main adjustments that the ANS does? (3)
ANS adjustments for:
- HR
- Stroke volume
- vasoconstriction
Voies motrices somatiques - Voies de contrôle des muscles squelettiques: which part of the body controls conscious movement
Cerebrum
Provide an example of an organ that is not under conscious control?
le réflexe rotulien

Tapping on the knee - the brief stretch of the muscle from the tap stimulates a arc reflex which automatically constricts the muscle and causes it to shoot out in a kicking fashion

GEN: some efferent pathways are not under conscious control, and instead represent reflex responses - rapid involuntary movements in response to a stimulus.
*sitting with your legs crossed and giving a tap right below the kneecap will cause the leg to kick out in response to the patellar (knee-jerk) reflex.
Caractéristiques des voies motrices somatiques - nommez les 7 qualités de SNC
SEVEN ways that efferent motor pathways can be distinguished from autonomic pathways

(1) Efferent motor neuron --> skeletal muscle

(2) Cell bodies ALWAYS in CNS

(3) Monosynaptic = only a single synapse b/w the CNS and the effector organ. These neurons are LONG.

(4) At neuromuscular junction, motor neuron splits into a cluster of axon terminals that branch our over the motor plate. (ANS = series of varicosities)

(5) Smaller synaptic cleft compared to ANS neurons

(6) Ach is the NT liberated. For ANS it is Epi for symp and NE for parasymp. Invertebrates = glutamate

(7) Ach effect is ALWAYS excitatory (ANS can be with excitatory or inhibitory
Comportements animaux - trois catégories - qu'est-ce que c'est?
•Comportement réflexe
•Simple et involontaire

•Comportement rythmique
•Sous‐jacent à la locomotion, respiration et fonction du coeur

•Comportement volontaire
•Le plus complexe et diversifié
Comportements réflexe - nommez les deux types
•Réponse intégrée la moins complexe
•Peu impliquer aussi peu que deux neurones
(monosynaptique) ou plus (polysynaptique)
Comportements réflexe - Monosynaptique
- seulement 2 neurones
- un seul synapse

exemple: les arcs de réflexe
- si on frappe le rotule, le choc résulte dans l’étirement du quadriceps
- les mécanorécepteurs font directement un synapse avec les neurones efférents dans le quadriceps, au niveau de la moelle épinière.

Monosynaptic reflex arc - contains only one neuron-to-neuron synapse in the chain from sensory neuron to effector neuron. These types of arcs can have more than 2 neurons, as long as there is only one neuron-to-neuron synapse along any path from the stimulus to the response.
Comportements réflexe - Polysynaptique
- un interneuron joue un rôle dans l’intégration d’information; permet un niveau additionnel de complexité.

exemple: des arcs de réflexe
- cette organisation polysynaptique permet deux ou plusieurs réponses.
- par exemple: un muscle peut se relâcher tandis que l’autre se contracte (ex: au niveau de l’étirement du quadriceps.)

Adding interneurons to a reflex arc greatly increases the potential responses of the arc and the complexity of the processing.
ex. C. elegans response to touch
Les neurones des arcs réflexes peuvent être organisés de deux façons - qu'est-ce que c'est?
Convergence et divergence des arcs réflexes

•Certains arcs réflexes ont les deux
Convergence des arcs réflexes
- Permet la sommation spatiale
In a convergent arrangement, many presynaptic neurons interact with a single postsynaptic neuron

Plusieurs receptors va converger sur un seul synapse
- de generer une action avec plus de puissance = *l'etendue de stimulation
- plus de recepteurs qui sont stimule = summation spatiale de reponse sera passer = augment la puissance de la reponse

ex. the activity of a single afferent neuron may be insufficient to excite the efferent neuron, but the simultaneous activity of many afferent neurons may be sufficient to cause a response.
* Convergence can also allow the comparison and integration of sensory signals from multiple parts of the body, increasing the complexity of information processing.
Divergence des arcs réflexes
- Peut amplifier le signal
In a divergent arrangement, a single presynaptic neuron forms synapses with many postsynaptic neurons.

Amplifie le signal aux plusiers site effectuers

- single signal = controls multiple independent processes
- amplifies the signal
- Allows the nervous system to engage in parallel processing, which allows very rapid integration of inputs and responses
- ultimately, allows for a coordinated and amplified response
Comportement rythmique - Géré par des ?
générateurs de patrons ---> Groupe de neurones produisant des dépolarisations rythmiques
et autosuffisantes

Pattern generators govern many important physiological processes and simple rhythmic behaviours such as chewing, walking, swimming, and breathing.
- self sustaining patterns of depolarization, independent of sensory input
Deux types de générateur de patrons - qu'est-ce que c'est?
•Cellule rythmogène: Une cellule à dépolarisation spontanée génère le rythme de l’ensemble du groupe

•Propriété émergente d’un réseau: La dépolarisation rythmique se produit grâce à l’organisation des neurones dans un réseau
Décris le cellule rythmogène:
Pacemaker cell - spontaneous rhythmic deploarization and thus controls the firing of all the cells in the network. *initiate the heartbeat in many kinds of animals

- une cellule rythmogène, toute isolée, peut se dépolariser d’une manière autonome.
Décris le Propriété émergente d’un réseau:
- on a besoin de plusieurs neurons pour travailler ensemble.
- une cellule qui se dépolarise, émet un signal, alors que la deuxième cellule se dépolarise, etc.

- made up of neurons that do not, as individuals, generate rhythmic depolarizations. Instead the rhythm is an EMERGENT PROPERTY of the network that manifests itself because of the organisation of the neurons in the network, rather than being an intrinsic property of the neurons themselves.

Various mechanisms can start the rhythmic oscillations. Often, input from a sensory receptor is needed in order to start the rhythm.
Comportement de nage chez la sangsue - décris le, et dessine une image
- lorsque les mécanorécepteurs détectent un mouvement adjacent, la nage est déclenchée.

Swimming behaviour can be initiated without a touch stimulus. An additional neuron in the circuit, sometimes called the swim excitor interneuron, can modulate the activity of the swim gating neuron or the central pattern generator itself in response to signals from the leech brain. (pathways not yet understood)

Slide 55 PDF #3
Les modulateurs de movement principales (pour le sangsue) c'est quoi - il y en a deux.
(1) Arc de reflex
(2) Oscillateur de nage
Describe tetrapod locomotion
Stereotyped reflexes, such as walking, running and swimming for tetrapods are called 'gaits'
Brainstem (pons and medulla) initiates the command to begin locomotion --> signal sent to a network of neurons in the spinal cord that acts as a central pattern generator (similar to the ones in leeches), --> coordinated motor output signals to the muscles that control the limbs, initiating rhythmic movements.

- lorsqu’on se déplace, on n’a pas besoin de penser au sujet de notre coordination.

- l’information au sujet de l’environnement est envoyée vers le SNC, afin de permettre l’interprétation et l’intégration; permet le raffinement et régulation du mouvement.
What does the cortex do in terms of locomotion?
•Le cortex participe afin de gérer la locomotion dans un environnement complexe
- guides locomotion in complex environments
- coordinates visual signals with locomotion
- signals are then sent to the brain stem and spinal cord to modify locomotion

The brain regulates and coordinates the activity of the spinal cord pattern generators, controlling the speed and smoothness of locomotion and adjusting locomotion in response to visual stimuli.

The integration of all of these sensory signals are sent to the cortex to refine and adjust the descending motor output in order to complete the planned movement successfully.
What does the cerebellum do in terms of locomotion?
•Le cervelet raffine la coordination des mouvements
(dommage = les mouvements saccadés)

Cerebellum:
- regulates the timing and intensity of signals of the spinal cord pattern generator
- when damage is inflicted here the movement is jerky and uncoordinated, they may stumble.

ACTION:
- cerebellum receives input from the stretch receptors and proprioceptors in the limbs, compares these signals to the intended movement and then sends signals to the brainstem to correct the movement if necessary thus coordinating locomotion.

The cerebellum not only receives signals from the proprioceptors and stretch receptors to manage movements, but it also receives input from the vestibular apparatus of the ear - involved in a sense of balance.
•La _____ ______ agit comme générateur de patron
moelle épinière
•Le _____ _______ initie le processus et régule la vitesse
tronc cérébral
What does the brain stem do in terms of locomotion?
Brainstem:
- regulates speed
- when stimulated by electrodes, initiates walking, trotting, running, etc. (modulates speed)
Is Sensory feedback necessary to generate rhythmic locomotory patterns?
Sensory feedback is not necessary to generate rhythmic locomotory patterns, but simply modifies the output of the pattern generator.
In the case of paralysed muscles when curare is applied (no nervous system interference), 'fictive locomotion' will occur when motor neurons produce rhythmic firing patterns when the central pattern generator is stimulated and sends signals to the motor neurons. (this occurs even though the muscle is paralyzed)
What are the steps for making voluntary movement?
STEPS TO MAKING A VOLUNTARY MOVEMENT:
(1) decision to move is made in the cerebral cortex of the brain
- incorporates inputs from the association cortex, supplementary motor cortex, the visual cortex, and the limbic system.

(2) Decision to move is then developed into a program for movement in the primary motor cortex
- this motor program is independence of the actual muscles that execute the program. (ex. you can write your name with your fingers and your toes)

(3) Primary motor cortex executes the motor program by sending signals along a series of tracts (groups of axons) to the spinal cord.
- two types: pyramidal and extrapyramidal
What is the difference between pyramidal and extrapyramidal?
PYRAMIDAL:
- direct pathway from the primary motor cortex to the spinal cord
- passes through the medullary pyramids
- major role: directing voluntary movements
- tracts cross over in the medulla

EXTRAPYRAMIDAL:
- indirect pathways to the spinal cord
- make multiple synaptic connections within the brain prior to entering the spinal cord
- control posture and balance

EX. Signing your name: fine movements of hands = pyramidal, maintenance of body position and orientation = extrapyramidal
Le _____ _______ permet de mettre une lien entre les informations visuelles
zone associative
What is the purpose of propriocepteurs?
Stretch receptors and proprioceptors in the limbs sense information about the position of the limbs and the impact of the feet on the ground during walking or running. These receptors send sensory feedback to the pattern generator, allowing the pattern generator to modify the output in response to changing environmental demands.
•La plupart des animaux peuvent apprendre et mémoriser grâce à la ________ du système nerveux
plasticité
Define:
- Apprentissage
- Mémoire
- Plasticité
•Apprentissage
• Le processus d’acquérir de nouvelles informations (l’apprentissage implique la formation et le renforcement des connections entre neurones.)

•Mémoire
• Rétention et remémoration d’information

•Plasticité
•Changements de fonction neuronale et synaptique en réponse à un stimulus
Mémoire et apprentissage chez les invertébrés - c'est quoi l'exemple ce qui était discuté en classe?
la limace de mer Aplysia
Decris l'Habituation (ou accoutumance)

C'est quoi la cause?
•Diminution de la réponse à un stimulus suivant une exposition répétée

•Permet à l’animal d’ignorer les événements répétés moins importants et se concentrer sur les événements nouveaux

• Causé par des changements au niveau de la terminaison présynaptique
• Canaux calcium inactivé diminue la libération de neurotransmetteur

Habituation occurs because of functional changes at the synapse between the sensory neuron and the motor neuron.
- Short term: Ca2+ channel in the membrane of the presynaptic axon terminal of the sensory neuron is inactivated
*touching siphon = AP< but less CA2+ flows into axon terminal therefore less NT is released

Morphological changes:
- number and location of NT-containing vesicles. for long term, these changes occur to a greater degree.
Where are the Ca2+ channels situated for the 'Habituation'
Ces canaux se situent aux terminaisons presynaptique!
Describe the effect of 'sensibilisation'. What is it caused by? Provide an example.
Increase in the response to a gentle stimulus after exposure to a strong stimulus.
Ex. Loud noise heard from basement = now acutely aware of all smaller noises around you. You are sensitized

With Aplysia:
- an electrical shock applied to the tail, will cause the gill-withdrawl reflex to be larger and last longer than unsensitized animals. Multiple strong shocks produce effects for more than a week.
- physiological changes also occur in the presynaptic axon terminal of the sensory neuron from the siphon. DIFFERENT: there is an increase in Ca2+ entry and increased NT release, rather than a reduction.

•Augmentation de la réponse à un faible stimulus suivant l’exposition à un fort stimulus
•Causé par des changements au niveau de la terminaison présynaptique
What are the cellular mechanisms of sensitization? (4)
(1) Serotonin is released from the axon terminal of the sensory neuron involved in the gill-withdrawl response

(2) 5-HT binds to G-protein-coupled receptr that activates adenylate cyclase --> 2nd messenger cAMP

(3) cAMP activates PKA --> phosphorylates voltage-gated K+ channels in the membrane of the axon terminal, inactivating them.

(4) voltage gated K+ channels are responsible for repolarizing the cell after the depolarization phase of an action potential. When inactivated, AP last longer, leasing to more Ca2+ influx through voltage-gated Ca2+ channels and greater NT release.
Which NT is involved in the short term effects of sensitization.
Serotonin = SHORT TERM EFFECTS OF SENSITIZATION
What happens when an electric shock is sent to the tail of the Aplysia
- The sensory neuron from the tail makes a synaptic connection with several interneurons.
- These interneurons make connections on the axon terminal of the sensory neuron involved in the gill-withdrawl response. An electrical shock to the tail sends an afferent signal to the interneurons --> release of NT serotonin onthe the axon terminal of the sensory neuron involved in the gill-withdrawl response.
Describe the long term sensitization molecular pathway.
- repeated electrical shocks
- repeated release of 5-HT from axon terminals --> increased levels of PKA --> enters the nucleus and phosphorylates a transcription factor called CREB-1 (cAMP response element building protein 1) --> promotes gene transcription
- genes code for proteins that increase PKA activity, increase the number of synaptic connections and their responsiveness,
Is the hippocampus involved in long term memory stockage?
•L’hippocampe est impliqué dans la mémoire à long terme, mais les souvenirs sont « stockés » ailleurs
What is Long term potentiation:
•Potentialisation à long terme (PLT): Une amélioration à long terme de la réponse postsynaptique résultant de la stimulation répétitive par le neurone présynaptique

: repetitive stimulation of a particular presynaptic neuron eventually leads to an increase in the response of the postsynaptic neuron.

*Long term potentiation is thought to be important in memory formation because it provides a mechanism in which repetitive activity of a particular neural pathway can leave a record of itself even after the activity has stopped.
Describe the molecular differences seen between weak frequency stimulation and elevated frequency stimulation.
If you have a stimulation that is less frequent, you will have a response that is modest (modest depolarization) (glutamate)

If you have a stimulation that is repetative - liberation of glutamate is amplified. Thius opens the Ca2+ channels and will intitiate a long term action potential = increases the response, and increases the connection and signalling between the two neurons = long term stimulation

Slide 66 - PDF #4