Lecture 23 - Brain Evolution and General Structure Flashcards
What are the types of tracts in the cerebral hemisphere?
L23 S46
Association:
-connects regions within a single hemisphere
Commissural:
-interconnect the two hemispheres
Projection tracts:
- connect hemispheres to other parts of brain and spinal cord
- forms internal capsule
What are the major components of the Diencephalon?
Epithalamus:
- Pineal body
- Parapineal body (organ)
- Choroid plexus
- Habenulae
Thalamus
Hypothalamus:
- Optic chiasma is cephalic boundary
- infundibular recess and stalk
- Posterior pituitary (pars nervosa)
What are the functions of the pineal body?
-Thought to be involved in emotional and visceral responses to odors
- Secretes melatonin (hormone):
- Regulates circadian rhythms
Lesions associated with precocious puberty
What are the functions of the thalamus?
- Relays all sensory information except smell to cerebral cortex
- Provides crude awareness
- Initial autonomic response of the body to intense pain (physiologic shock)
- Interpretation center for crude pain, temperature, light touch, pressure
- Plays a role in arousal and alerting
- Plays a role in complex reflex movements
What are the functions of the hypothalamus?
- Controls/integrate ANS
- Raises/Lowers arterial blood pressure and increases/decreases heart rate (posterior/anterior)
- Reception and integration of visceral sensory impulses
- Intermediary between nervous and endocrine systems
- Produces ADH and oxytocin
- Involved in psychosomatic disorders
- Associated with rage and aggression
- Controls normal body temperature
- Regulates food intake
- Maintains extracellular fluid volume
- Biorhythm oscillator
- Sexual center
What is the striatum?
-Refers to the collection of basal nuclei (basal ganglia) that develop in the floor of the telencephalon
What is the lamina terminalis?
- Original cephalic boundary of the neural tube
- Separates the two lateral ventricles
What is the pallium?
- The primitive roof of the telencephalon.
- It lacks a true cortex.
- It serves as a primitive sensory and association area and receives information from the olfactory apparatus and some from the thalamus.
What is the neocortex?
- In mammals, the neocortex is added on top of the pallium.
- Makes up the majority of our cerebrum.
- Divided into Frontal, Parietal, Temporal, Insula, and Occipital Lobes.
What are the functions of the occipital lobe?
- Integrates eye focusing movements
- Correlates visual images with visual memory.
- Involved in conscious perception of vision.
- Separated from parietal lobe:
- Parietooccipital sulcus
What are the functions of the parietal lobe?
- Somatesthetic interpretation:
- Postcentral gyrus
- Understanding speech
- Auditory association cortex
- Wernicke’s Area
-Formulating words to express thoughts and emotions
What are the functions of the frontal lobe?
- Voluntary motor control:
- Precentral gyrus
- Motivation
- Aggression
- Mood
- Personality
- Cognitive processes
- Verbal communication:
- Broca’s area
What are the functions of the temporal lobe?
- Receives/interprets olfactory and auditory sensations
- Responsible for storage of memory related to auditory and visual experiences.
What are the functions of the insula?
-Involved with memory
- Psychic cortex:
- Highest levels of brain function:
- Abstract thought
- Judgement
- Highest levels of brain function:
What are the nuclei of the Corpus Striatum?
- Putamen: large subconscious movements of skeletal muscles.
- Globus pallidus: regulates muscle tone.
- Caudate nucleus
What are the main subdivisions of the substantia nigra and characteristics of them?
- Dorsal: Pars compacta
- Melanin containing neurons
- Dopaminergic neurons
- Ventral: Pars reticularis
- Iron-containing glial cells
- Serotonin and GABA
What are the components of the limbic system?
- Amygdaloid body
- Hippocampus
- Cingulate gyrus
- Parahippocampal gyrus
- Hypothalamus
- Mammillary bodies
- Anterior nucleus of thalamus
What are the functions of the limbic system?
- “Emotional” brain:
- Emotional and motivational aspects of behavior
- Provides emotional component to learning process:
- Especially the amygdala
- Associated with memory:
- Especially the hippocampus
-Associated with pain/pleasure, rage.
What is the amygdala and what are its functions?
- Large nuclear group in temporal lobe
- Receives info from olfactory tract, limbic cortex and various regions of the neocortex.
What are the regions of the amygdala?
- Large basolateral region:
- Provides direct input to basal ganglia and motor system.
- Small corticomedial group of nuclei:
- Related to olfactory cortex.
- Medial and central nuclei:
- Connected to hypothalamus
What is the function of the Papez circuit?
-EMOTIONS
What pathologies are associated with the limbic system?
- Voracious appetite
- Increased (perverse) sexual activity
- Docility:
- Loss of normal fear/anger response
- Memory loss:
- Damage to hippocampus portion results in cells undergoing calcium-induced changes associated with memory
- Kluver-Bucy Syndrome:
- Results from bilateral destruction of amygdala
What are characteristics of Kluver-Bucy Syndrome?
- Increase in sexual activity
- Compulsive tendency to place objects in mouth
- Decreased emotionality
- Changes in eating behavior
- Visual agnosia
What are the major relay nuclei of the thalamus?
- Sensory
- Motor
- Reticular
- Anterior
What are the thalamic sensory relay nuclei?
- Medial geniculate body:
- Auditory
- Projects to primary auditory cortex in temporal lobe
- Lateral geniculate body:
- Visual
- Projects to primary visual cortex in occipital cortex
- Ventral posterior nucleus:
- General sensations and pain
What are the thalamic motor relay nuclei?
- Ventral lateral:
- Voluntary motor
- Ventral anterior:
- Voluntary motor and arousal
- Subthalamic:
- Voluntary motor
What are the functions of the thalamic reticular relay nuclei?
-Modifies neuronal activity in the thalamus
- May be involved in:
- Regulating sleep-wakefulness cycle and levels of awareness.
What are the functions of the thalamic anterior relay nuclei?
-Concerned with certain emotions and memory
- Receives input from:
- Hippocampus
- Mammillary bodies
What are the hypothalamic nuclei?
- Mammillary bodies
- Involved in olfactory reflexes and emotional responses to odors
- Relay stations for olfactory neurons to inferior colliculi
- Supraoptic nuclei:
- Send projections (axons) that release neurohormones into capillaries in the posterior pituitary:
- Oxytocin
- Vasopressin
- Send projections (axons) that release neurohormones into capillaries in the posterior pituitary:
- Suprachiasmatic nuclei:
- Located immediately above optic chiasma
- Acts as a master biological clock, controlling circadian and circannual rhythms
- Set to light-dark cycle by a direct retinal projection to the suprachiasmatic nucleus
