Brain Flashcards

Question

cerebellum

Answer 1

maintenance of balance and posture coordination of movements- especially across joints motor learning

Answer 2

tectum controls rapid orientation of the head and neck- superior colliculus- vision inferior colliculus- sound substantia nigra- Parkinson's disease associated with sleep, wake cycles, alertness, temp regulation

Answer 3

acts as a switchboard takes information from PNS and passes to cortex NB- hypothalamus hormones metabolic control e.g. hunger, body temp

Answer 4

it plays a key role in: * movement * attention * perception * awareness * thought * memory * language * consciousness

Answer 5

* a series of interconnected nuclei * movement regulation * skill learning * habit formation * reward systems * selection of appropriate behaviours * self-initiation of behaviours

Answer 6

Pathways to and from the brain

Answer 7

the middle of the cord (that looks a bit like an H) is made up of neurones and other cells (grey matter). outside cord- made up of fibres (white matter) carry information up and down the cord.

Answer 8

touch proprioception vibration pain temperature sensory information enters the spinal cord at the dorsal horn

Answer 9

located in the ventral spinal cord the neurones make direct contact onto muscles stimulation causes movement each cell is part of a motor unit

Answer 10

all motor neurones that innervate a single muscle are called a motor pool more muscle fibres than neurones so each fibre is innervated by a single neurone but one neurone may innervate many fibres The size of this innervation is important as muscles that are capable of fine movements are innervated by more neurones.

Answer 11

Maps are referred to as ‘somatotopic’ when that space is related to locations on the body, such that adjacent neurons in the neural tissue respond selectively to stimuli presented to adjacent locations on the body.

Answer 12

fibre tracts that carry information to and from the brain

Answer 13

The corticospinal and rubrospinal tracts

Answer 14

The vestibulospinal and reticulospinal tracts

Answer 15

The corticospinal and rubrospinal tracts make up the the lateral descending system * fibres of the lateral system are in the dorso- lateral part of the spinal cord. * they connect to motor neurones in the lateral part of the ventral horn. * this system influences lateral musculature.

Answer 16

Corticospinal fibers strongly influence movement of every part of the body and is particularly useful for individual finger use. 2. Other descending fibers, primarily the rubrospinal tract, can compensate almost completely for the loss of descending corticospinal input. 3. The one ability of the descending corticospinal tract for which no other tract can compensate is the ability to use the fingers individually. Individual finger movements are the sole province of the corticospinal system.

Answer 17

The vestibulospinal and reticulospinal tracts make up the the medial descending system. * fibres of the medial system are in the ventro-medial part white matter. * they connect to motor neurones in the medial part of the ventral horn. * this system influences medial musculature.

Answer 18

1. the medial systems are involved in the control of balance and posture. 2. these functions happen with little conscious control. 3. the vestibulospinal tract retains balance when the body is moved – external disturbance. 4. the reticulospinal tract helps us retain posture and balance during our own volitional movements – internal disturbance.

Answer 19

carries sensory information from the joint and skin about: * fine touch. * vibration. * two-point discrimination. * proprioception (position) from the skin and joints.

Answer 20

The lateral spinothalamic tract conveys * crude touch. * a sense of being touched without knowledge of where. * pain. * temperature.

Answer 21

Regardless of where the cell bodies are, both the sensory and motor axons run in the same nerves. * These nerves are spinal nerves.

Answer 22

The cell bodies of incoming sensory neurones lie outside the spine in a series of ganglion – called the Dorsal Root Ganglion (DRG) This is unlike the motor neurones that have their cell bodies in the ventral horn.

Answer 23

* There are 31 pairs of spinal nerves. * The positions in the spine these nerves will determine what part of the body each spinal nerve serves. * Because some parts of the body have more muscles and more sensory receptors. The size of the nerve and the amount of information carried by the nerve will be different.

Answer 24

an area of the skin supplied by nerves from a single spinal root

Answer 25

Chickenpox is caused by the varicella zoster virus ). After recovery the virus remains in your DRG. * Sometimes in later life the virus can reactivate producing a painful or itchy rash that is isolated to a single dermatome

Answer 26

is the ability to discern that two nearby objects touching the this ability reflects how finely innervated an area of skin is

Answer 27

Motor units make up motor pools: * a lower motor neurone (or alpha motor neurone) in the spinal cord innervates a muscle. * each motor neuron synapses with multiple fibres within the muscle. The motor neurone and all the muscle fibres it contacts define the motor unit. * cross section through the muscle shows the relatively diffuse distribution of muscle fibres (dark fibres) contacted by a single motor neuron

Answer 28

he arms and legs (particularly the hands and feet) have many highly innervated muscles and have a high density of sensory receptors. Because of this the portions od the spinal cord that provide the spinal nerves to the arms and legs are enlarged

Answer 29

* dorsal horn - contains sensory neurones. these receive sensory information and send this up to the brain. * Ventral horn – contain neurones that send messages directly to the muscles. * intermediate zone –contain interneurones. these integrate information. e.g – inhibition.

Answer 30

timulus intensity determines size of receptor potential & thus frequency of action potentials firing frequency codes for intensity (“rate code”) very non-linear usually codes for intensity of contrast between two levels.

Answer 31

* Motor neurons use a rate code to signal the amount of force to be exerted by a muscle. * An increase in the rate of action potentials fired by the motor neuron causes an increase in the amount of force that the motor unit generates.

Answer 32

* For small forces small motor units are recruited first, as the required force increases, larger motor units are recruited. * Size principle states that, with increasing strength of input onto motor neurons, smaller motor neurons are recruited and fire action potentials before larger motor neurons are recruited.

Answer 33

* humans before and after dynamic training. - Note the increased rate of tension development after dynamic training * increased rate of of tension achieved after training is accompanied increase in rectified surface EMG activity in the early phase of contraction.

Answer 34

Stretching a muscle is detected in the muscle and leads to increased activity in sensory neurones that in turn leads to an increase in the activity of motor neurons that innervate the same muscle, while inhibiting the motor neurons that innervate antagonists.

Answer 35

* rapid automatic control of movement. * little or no voluntary control. * some are very simple: * stretch reflex. * some are more complex: * swallowing, breathing. * these mainly happen in the spinal cord and low in the brain stem.

Answer 36

the brainstem sits at the top of the spinal cord and is made of three parts: 1. medulla 2. pons 3. midbrain

Answer 37

The reticular formation is a set of interconnected nuclei that are located throughout the brainstem. The vestibular nuclei (VN) are the nuclei for the vestibular system and are located in the brainstem.

Answer 38

The vestibular system is thesensory system that provides the sense of balance and spatial orientation for the purpose of coordinating movement with balance The vestibulospinal tract originates in the vestibular nuclei. They send most of their output to the spinal cord and to the muscles that move the eyes.

Answer 39

* the reticular formation is a set of interconnected nuclei that are located throughout the brainstem. * It is a very old part of the brain. * The reticulospinal tract originates in reticular formation. * These tracts function in maintaining tone, balance, and posture.

Answer 40

* the cerebellum has a very conserved, highly folded structure in all animals * 10% volume of the brain. * More than neurones than the cortex. * 69Billion v 16Billion * input:output connections ratio. * 40:1

Answer 41

Superior cerebellar peduncle * efferent (out) pathway to the red nucleus and the cortex (via the thalamus) & sup colliculus. Middle cerebellar peduncle: * most fibres originate in the pons * input from sensory, visual, vestibular and motor systems. * but its largest input is from the cortex. Inferior cerebellar peduncle * carries information to and from the the spinal cord (and the body) and vestibular nuclei

Answer 42

The red nucleus is a roughly spherical collection of cell bodies in the midbrain. It is called the red nucleus because it is extremely vascular. In fresh tissue the red nucleus is distinctly pinker than the surrounding tissue. The red nucleus receives a very large input from the cerebellum and from the primary motor cortex.

Answer 43

* movement regulation * skill learning * habit formation * reward systems * selection of appropriate behaviours * self-initiation of behaviours

Answer 44

* the DIRECT pathway that runs DIRECTLY through the basal ganglia * the INDIRECT pathway takes a longer loop through the basal ganglia.

Answer 45

DIRECT * short loop though the basal ganglia. * has excitatory effect on cortex. * Net effect is pro-movement. INDIRECT * long loop through the basal ganglia. * has inhibitory effect on cortex. * Net effect is anti-movement.

Answer 46

basal ganglia * damage to the BG produces states where there is too much, or too little movement. cerebellum * damage to the cerebellum produces states where movements can still be made, but they are uncoordinated.

Answer 47

* Because of the close relationship with the body surface & muscles, both the primary sensory and motor cortex have detailed somatotopic maps of the body in them. * Areas of the body with many highly innervated muscles and densely packed sensory receptors have expanded representations in the brain.

Answer 48

Neurones in the primary motor cortex have a simple relationship to movement. They fire around 5 to 100 ms before movement onset and can code for the basic parameters of movement, i.e.: * Force. * Direction. * Extent. * Speed

Answer 49

As we have seen neurones in the primary motor cortex have a simple relationship with movement parameters. Neurones in the non-primary motor cortex have a more complex relationship to movement. They code for the more complex aspects of movement

Answer 50

Neurones in the non-primary motor cortex have a more complex relationship to movement. They code for the more complex aspects of movement, for example: * planning movement. * spatial guidance of movement. * sensory guidance of movement.

Answer 51

Neurones in the non-primary motor cortex code for more complex aspects of movement. They code for the more complex aspects of movement, for example: * coordinating temporal sequences of actions. * bimanual coordination. * initiation of internally generated as opposed to stimulus driven movement *NB – the SMA is well connected to the basal ganglia.

Answer 52

* A monkey is trained to perform a complex bimanual task that requires the animal to push a peanut through a hole to collect a peanut. * After a lesion of the SMA the animal cannot perform this task and the function does not recover

Answer 53

These area are needed for complex movements and are highly interconnected with the motor areas

Answer 54

* touch: vibration, heat, pain, pressure. * Proprioception: Afferent information, including joint position sense, kinesthesia, and sensation of resistance: * Joint position sense: The ability to recognize joint position in space. * Kinesthesia: The ability to appreciate and recognize joint movement or motion. * Sensation of resistance: The ability to appreciate and recognize force generated within a joint.

Answer 55

* integration of sensory, visual information to execute complex movement in the environment. * representations for different motor effectors (e.g. arm vs. eye) * a command apparatus for operation of the limbs, hands and eyes within immediate extrapersonal space

Answer 56

The most important tract in the human for precise control of the limbs. * Origin: * primary motor cortex (30%) * Premotor, supplementary (30%) * Somatosensory, parietal, cingulate (40%) * About 1 million fibers in humans. * 90% cross at lower medulla * All are excitatory

Answer 57

he complexity of the movements the nervous system controls increases as you move toward (and through the brain): spinal cord – simple reflexes. medulla – complex reflexes. cerebellum – coordinated movement. basal ganglia – programmed movements. cortex – complex conscious movements.

Brain Flashcards

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