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Flashcards in Cortex 3 Deck (29):
1

what does M1 correspond to?

the primary motor area

Brodmann's area 4

2

how does M1 influence the motor system?

directly through the corticospinal and corticobulbar tracts

indirectly through their projections to the red nucleus and the RF

3

how is M1 organized?

somatotopically arranged

organized into radially arranged columns of neurons extending vertically from the surface into the depths of the cortex

a single column is a functional unit responsible for directing small groups of muscles acting on a single joint
-encodes the amount of force (frequency)
-trajectories are encoded by populations of neurons

4

describe the motor homunculus:

similar to sensory homunculus

large area for hand and face

eyes are gone though- doesn't control movement of eye but controls eyelids (eyelids are done by frontal eye field (area 8)

DOUBLE REPRESENTATION-

5

what is double representation?

- muscle groups are represented twice.

posterior- M1-4p- can be activated by attention w/out any sensory feedback and has been suggested to be important for initiation of movements -- works with BG

anterior- M1-4a- dependent on sensory feedback
-complex sensory motor interactions
-also is activated by imaginary finger movements and listening to speech while making no actual movements
-important in executing movements involving complex sensorimotor interactions

6

what are results of a lesion to M1?

UMNL contralateral symptoms
-immediate contralateral paresis, hypotonia, hyporeflexia
-weeks--> spasticity, hyperreflexia, Babinskis sign
-MAINLY weakness

7

what are trajectories?

?

summation determines trajectory

8

what does the motor association cortex consist of?

Brodmann's area 6 and parts of 8 and 44

includes the supplementary motor area (M2), the premotor area, the frontal eye fields and the posterior part of Broca's area

9

what is the premotor area?

what Brodmann's area?

what are its 2 divisions?

afferents? efferents?

function?

Brodmann's area 6

divided into PMA lateral dorsal & lateral ventral

poorly understood

afferents primarily from posterior parietal cortex

efferents to BS (medial descending system- reticulospinal)

thought to control proximal muscles that project a movement to the target

areas change over time as response becomes more automatic

movements are triggered by external sensory events (how sensory stim will be used to direct movements )

10

what does the posterior parietal lobe play a role in?

providing visual info for targeted movements (5,7,39)

11

because of the cephalic flexure, what terms are now changed at this level?

dorsal= up
ventral = down

12

what does the lateral dorsal premotor area do?

movement selection
-integration of sensory info into motor commands
-specific of movement parameters- amplitude, speed and direction

involved more with REACHING (afferents from parietal cortex; spatial relations and orientation; visual guided motion; sends strategy to BG)

involved with learning to associate a sensory event with a specific movement= ASSOCIATIVE LEARNING

13

what are results of a lesion to the lateral dorsal premotor area? (PMd)

have difficulty with associative learning

awkward movement
pick the wrong strategy

14

what does the lateral ventral premotor area do? (PMv)

densely interconnected with the hand area of M1 and the parietal lobe

related to grasping - conforming the hand to the shape of objects

also involved in the cognitive aspects of motor control
Mirror neurons:
- is active when an action is observed
- encode higher order, abstract representations for goal oriented actions
- form of motor learning?

15

what is the general result of a lesion to the premotor area?

impairs the ability to develop an appropriate strategy for movement

16

what is the supplementary motor area (M2) ?

what is it involved in? function?

SMA is involved in planning complex movements and in coordinating movements involving both hands

thought to function in the advanced planning of self initiated movements-especially bilateral ones

involved in learned sequences from memory in the absence of visual cues

more concerned with programming than executing

important in programming and coordinating complex sequences of movement

also play a role in coordinating posture and voluntary movement

NOT sensory drive; no visual/auditory/tactile guidance

17

what are results of a lesion to M2?

-can't orient hands and digits appropriately while reaching for something (hands assume awkward positions as it approaches object)

-subjects are severely impaired in their ability to use both hands to retrieve a morsel of food stuck in a hole

-subject's have a difficult time making postural adjustments that are needed during a movement

18

what do frontal eye fields control?

what do they work with?

initiation of saccades

works with:
-supplementary eye fields
-parietal eye fields
-superior colliculus

stimulation of this area results in conjugate deviation of the eyes to the opposite side

contributes to all volitional and visually guided saccades as well as to pursuit and mergence movements of the eye

19

what is the prefrontal lobe responsible for?

formulating plans and strategies, alone with a person's personality

20

what is the prefrontal cortex?

what is its function?

this brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior

the basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals

EXECUTIVE FUNCTION
-planning ahead- predicting future
-monitoring- evaluating a situation
-sustained attention- keeping eyes on target
-gorl directed behavior
-working memory- short term memory & rehearsal
-problem solving

21

what are the 3 areas of the pre frontal cortex?

what are the 2 divisions?

dorsal
ventral
orbital/frontal (sits on frontal bone)

Lateral dorsal and lateral ventral

22

what does the lateral dorsal prefrontal cortex do?

PFLD- 8,9,46

characterizes the spatial relationships b/w stimuli and ascertains which responses should be executed ("how/where" pathway)
-transforming perception into action

responsible for the monitoring of info in (spatial) working memory
-working memory is defined as "the info that is currently available in memory for working on a problem

does this by evaluating the situation from a sensory analysis, then develops a plan to deal with the problem
(ex: only answer your phone when appropriate)

also involved in planning ahead

23

what does the lateral ventral prefrontal cortex (PFLV) do?

ASSOCIATIVE LEARNING & DECISION MAKING
-necessary for normal learning of arbitrary visuomotor associations (no spatial or delay component)
-characterizes the features and attributes of stimuli in the environment- "what pathway"
-guiding the selection and retrieval of semantic/linguistic knowledge
-inhibition- resolve negative feelings; enables to direct attention to helpful solutions rather than ruminate over problems

Left side:
-control attention
-(maintain focus in distracting environments)

Right side:
-vigilance

*dopamine- activated

24

what is the orbitofrontal cortex (OFC)?

makes up an important part of who we are by regulating our emotions


inputs consist of internal environmental info
-subjective judgements we use in defining responses to stimuli: fear, hunger, thirst, sexual urge, love, envy, jealousy, ethics, morals
-the drive or value generated by limbic system

Output
-OFC-planning process that occurs- regulates one's behavior and physiological response, by using the consequence of one's action

THUS,
-the OFC takes care of many important functions by combining sensory observations and the reward system
-encodes the reward value (value of outcomes) as they are attained

25

afferent input for the OFC?

-from the dorsomedial thalamus and the temporal cortex (both linked to memory)
-the ventral tegmental area (associated with reward system)
-the olfactory system
-the amygdala

26

efferent output from the OFC?

sends signals to the limbic system (responsible for moods and emotions
-the cingulate cortex
-hippocampal formation
-temporal cortex
-lateral hpothalamus
-amygdala; along with other areas of the frontal lobe

27

what are results of a lesion to the OFC?

many behavioral abnormalities would arise:
-inappropriate behavior and emotional changes are imminent
-pateitns will become more impulsive
-they typically show greater unprovoked emotions of anger and less unwarranted happiness
-sense of time is impaired
-lack of initiative, unconcern or underestimation of the gravity of a situation are all side effects that hinder patients' relationships and every day lives
-frontal lobe damage can cause patients to be unable to plan or correct certain behaviors, though they can verbally express the right course of action

face and voice recognition problems

28

what activates the OFC?

smells activate neurons in the OFC
-reward value of smell

ease activates neurons in another part of OFC
-ex: once full, the OFC neurons no longer respond
-whereas, the neurons in the primary taste cortex are regulated by the identity of taste, not the reward value

The inferior temporal cortex also sends visual inputs directly to OFC

individuals react differently to itms or images depending on their reward association
-ex: OFC repsonds to face expression by signifying behavior should change

somatosensory inputs (touch, pain, etc) are sent from the post central gyrus; the amygdala transmits signals to the OFC. the more please and pain there is, the more OFC activity occurs

patients with damage to the ventral part of the frontal lobe may feel pain, but report that it does not feel very bad

29

what is the cingulate gyrus? what does it do?

involved with emotion formation and processing, learning and memory

highly influential in linking behavioral outcomes to motivation (a certain action induced a positive emotional response, which results in learning)

coordinates sensory input with emotions

emotional responses to pian

regulates aggressive behavior

implicated in schizophrenia