lec 6 Flashcards
(23 cards)
Two main motor functions
- Timing
- Movements and perceptions - Maintaining movement accuracy
- Error correction
-Compares intended movement with actual movement
Flocculus involved in
eye movements + balance
Damage to the basal ganglia can produce two main types of motor symptoms.
1.) Hyperkinetic symptom
- Damage to the caudate putamen may cause unwanted writhing and twitching movements called dyskinesias; seen in Huntington disease and Tourette syndrome.
2.) Hypokinetic symptom
- Damage to the basal ganglia may result in a loss of motor ability, leading to rigidity and difficulty initiating and producing movement;
seen in Parkinson disease.
HOW THE BASAL GANGLIA
CONTROL MOVEMENT FORCE
Volume control theory
- The globus pallidus internal acts like a volume control on the motor
cortex.
- If it is turned up, movement is blocked; if it is
turned down, movement is allowed.
- Two pathways within the basal ganglia
[Direct]
- When activated, the globus pallidus internal is inhibited, and the pathway is freed to produce movement.
[Indirect]
- When activated, the globus pallidus internal is activated and inhibits the thalamus, thus blocking movement
Nuclei forming the basal ganglia include
- The Striatum (Caudate nucleus and putamen)
- Subthalamic nucleus
- Globus pallidus
The basal ganglia
Receive input from
- All areas of the neocortex and
allocortex, including motor cortex
- The nigrostriatal dopaminergic system
from the substantia nigra
Project back to the motor cortex and
substantia nigra
Serve a wide range of functions,
including association or habit learning,
motivation, emotion, and motor control
Limb muscles are arranged in pairs.
1.) Extensor
- Moves (extends) the limb away
from the trunk
2.) Flexor
- Moves the limb toward the
trunk
Two kinds of neurons in the spinal column’s ventral horns
Interneurons project to motor neurons.
Motor neurons project to muscles of the body.
- Laterally located motor neurons project to the muscles that control the fingers and hands.
- Intermediately located motor neurons project to muscles that control the arms and shoulders.
- The most medially located motor neurons project to muscles that control the trunk.
what are the 4 motor tracts
1.) Corticospinal tract
2.) Lateral corticospinal tract
3.) Ventral (anterior) corticospinal tract
4.) Motor Tract Organization
Corticospinal tract is
Main efferent pathways from the motor cortex to the brainstem to the spinal cord
Lateral corticospinal tract is
- Branches at the brainstem level, crossing over to the opposite side of the brain and spinal cord
- Moves the digits and limbs on the
opposite side of the body
Ventral (anterior) corticospinal tract is
- Remains on the same side of the brain and spinal cord
- Moves the muscles of the midline body (trunk) on the same side of the body
Motor Tract Organization
Interneurons and motor
neurons in the left and
right anterior spinal cord
tracts are topographically
arranged
Roadblocks to knowledge about behavioral disorders
- Subjective nature of behavior.
- Caregiver and family subjectivity in noticing and reporting symptoms.
- Lack of specificity in identifying symptoms.
- Professional evaluators with different conceptual bases
Classification systems are frequently revised in light of new knowledge
- World Health Organization: International Classification of Diseases(ICD-10)
- American Psychiatric Association: Diagnostic and Statistical
Manual of Mental Disorders (DSM) - National Institute of Mental Health (NIMH): Research Domain Criteria (RDoC)
psychiatry 3 general behavioural categories that are most studied + understood
Psychoses, mood disorders, and anxiety disorders
Fritsch and Hitzig Discovered they could
electrically stimulate the neocortex of an
anesthetized dog to produce movements of the mouth, limbs, and paws on the opposite side of the dog’s body
PREMOTOR AREA
receives input from parietal cortex and is
involved in selecting movements from a movement
lexicon in response to external cues.
Cisek’s affordance competition hypothesis proposes
premotor cortex is constantly updating potential future
motor plans based on sensory input and internal goals.
Decision-making is embedded in motor system rather than a
higher-order “decision-making centre”
Ventral premotor area contains
mirror neurons which
respond selectively when viewing an animal perform
an action
Emotions are
Cognitive interpretations of subjective feelings.
Motivation
Behavior that seems purposeful and goal-directed.
Neuroanatomical structures related to emotion and motivation.
Hypothalamus
Limbic system
Frontal lobes
