Mod 4 Flashcards
Dysarthria
Incoordination and/or slowness of speech
- cerebellar dysarthria: ataxic
Basal nuclei related dysarthria: hyper or hypokinetic
UMN or LMN: muscle weakness
Aphasia
Absence of speech
- involves multiple anatomic regions
- can be a result of damage to any area of the cortex
- the characteristics of the aphasia can reveal the area of the lesion
- Broca’s, Wernicke’s, Global
Structures of the limbic system
Hippocampal formation and amygdala
Largely a temporal lobe structure
Functions of the limbic system
Species preservation
Self preserfavtion
Expression of emotions and memory
Limbic system and the somatic motor system
Reticular formation: prepare for flight or escape
Reticulospinal tracts
- reflexes of trunk (axial) muscles and limbs
- maintains posture and balance
Basal nuclei
- limbic loop: motivational and emotional aspects of movement
- seems to be involved in sympathetic response
- impulse control
Facial expressions and emotionally charged body movement
Function of hypothalamus
Maintain homeostasis
- appetite
- fluid/electrolyte balance
- glucose balance
- metabolism
- sleep
- body temperature
Hypothalamic control of the ANS
PSNS and SNS responses
Hormone release which acts on cells of the anterior and posterior pituitary
Anterior pituitary hormones
CRH stimulated ACTH release: adrenal hormones
TRH stimulates TSH release: thyroid hormones
GnRH stimulates LH/FSH release
GHRH stimulates growth hormone release: liver
Posterior pituitary hormones
ADH
Oxytocin
Acute phase stress response
Limbic system/amygdala
Hypothalamus releases CRF
Pituitary releases ACTH
ACTH triggers cortisol release
If stress persists, chronic cortisol release creates adverse response.
Risk factors for stress
Lack of education
Previous trauma
Childhood adversity
Child abuse
Family psychiatric history
Proir psychological difficulties
Trauma severity
Lack of social support following the event
Subsequent life stress
Factors that predict successful coping
Hardiness
Self-enhancement
Positive emotion
Neuroplasticity beyond early development
synapse modification
Long term potentation
Results in well-established connections
Repeated exposure to a stimulus results in increased level of activity at that synapse
Long term depression
Results in poor connectivity, potentially cell death
Repeated exposure to a stimulus results in decreased level of activity at that synapse
Healing and learning
Require a change in neural connections
Neurogenesis is rare after early childhood, but gliogenesis persists throughout the lifespan.
Healing after CNS injury is often mediated by
Glial cells that salvage and strengthen surviving neurons
Facilitate new axon: dendrtitic connections
Spontaneous recovery involves
Neurite growth
Angiogenesis
Synaptogenesis
Experience dependent plasticity
Maladaptive prevents recovery
Adaptive promotes recovery
How does the brain adapt and reorganize in response to activity
Synaptogenesis
White matter changes
Altered gene expression
LTP is associated with skill acquisition, and LTD can lead to microglial synaptic pruning
Types of memory
Sensory or immediate: lasts no more than a few seconds
Short term: lasts seconds to minutes
Long term: permanent
Types of long term memory
Declarative/explicit
- facts and events
- to form long term declarative memories, the hippocampus must be intact
Nondeclarative/implicit
- procedures and responses
Reticular formation afferents
Sensory
Motor
ANS
Hypothalamus/limbic system
Efferents of the reticular formation
Every level of the CNS
Reticular formation control of motor function
Corticoreticular fibers synapse with motor interneurons
Function in locomotion and postural control
Control muscle tone and reflex activity
Maintains horizontal gaze steady when the head moves
Reticular formation control of pain sensation
Collateral branches of pain pathways extend to the RF
RF sends signals to the
- hypothalamus and limbic systems –> emotional response
reticulobulbar and reticulospinal tracts –> sertotonergic inhbition of pain
Reticular formation control of ANS
Receives afferents from
- cerebral cortex
- hypothalamus
- limbic system
- ascending sensory pathways
The reticulobulbar tract and reticulospinal tract carry signals to the ANS center of the brainstem
Confusion
impairment speed and clarity, associated with inattentiveness and disorientation
Drowsiness
inability to remain awake without external stimulation
Stupor
only vigorous external stimulation can arouse the patient; once aroused, responses remain markedly impaired
Coma
deep sleep-like state; patient cannot be aroused even with vigorous or repeated external stimulation
Increased intracranial pressure
Trauma –> swelling –> increased ICP
The only outlet for the cranium is the foramen magnum –> pressure on the brainstem
- medulla –> damage to respiratory centers –> apnea
- midbrain –> RF damage and hypersomnia –> coma
T6 and above
Descending reticulospinal tracts innervate sympathetic signals to the ANS organs of the thorax
Early –> reduced SNS activity
Late –> reflex SNS hyperactivity
