L06 Flashcards
What is neurogenesis?
The production of new neurons.
- Neural progenitor cells produce neurons when they undergo asymmetrical cell division. Human neurogenesis largely stops four months after conception.
- There may be a little neurogenesis in some adult mammals, but this is controversial.
What is apoptosis?
A process of programmed cell death that occurs in multicellular organisms.
- Apoptosis is a highly regulated and controlled form of cell suicide that ensures a dying cell does not cause problems for its neighbors.
- Human neural progenitor cells undergo apoptosis 125 days after conception.
How does the brain develop from conception?
A hollow, enclosed neural tube forms during the first month of human development. The first cells are neural progenitor cells, and they initially only exhibit symmetrical cell division: each cell becomes two of the same type.
This period of symmetrical cell division ends and asymmetrical cell division starts 40 days after conception (in humans). Over the next 85 days, each time a neural progenitor cell divides, it produces one neural progenitor cell and either one neuron or one glial cell.
By day 125 after conception, there are over 100 billion neurons in the human brain. This is the most neurons we ever have. Many die before birth, seemingly because they can’t find a place in the network.
What is the midbrain and what are its 2 major parts?
A collection of nuclei that orchestrate complex reflexive behaviors, such as species typical responses to threat and pain, as well as orienting responses to sounds and lights.
Its 2 major parts are the tectum and the tegmentum.
What is the tectum and what is its function?
The tectum (“roof”) appear as two pairs of bumps on the dorsal surface of the midbrain.
The top 2 bumps are the superior colliculi. They are involved in orienting the animal to things seen in peripheral vision.
The bottom 2 bumps are the inferior colliculi. They are involved in orienting to unexpected sounds.
What is the tegmentum and what is its function?
The tegmentum includes several structures that coordinate and motivate complex species-typical movements. Some areas of the tegmentum process pain and orchestrate behavioural responses to threats.
What is the hypothalamus and what is its function?
The hypothalamus is a bilateral structure made up of several nuclei, which generally regulate autonomic nervous system activity.
They hypothalamus is critically involved in behaviors that directly relate to survival (i.e. the four F’s: feeding, fighting, fleeing and mating).
Different hypothalamic nuclei control body temperature, sleep-wake cycles, hunger, and social behavior, among other things.
One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system (release of hormones into the blood stream) via the pituitary gland.
What is a hormone?
A chemical substance that is released by an endocrine gland and that has effects on target cells in other organs.
What is an endocrine gland?
A gland that secretes chemical signals (hormones) into the bloodstream. Much of endocrine system is controlled by hormones produced by cells in hypothalamus
What is the thalamus?
A bilateral structure that is divided into several nuclei, many of which relay ascending sensory information to different regions of the cerebral cortex.
For example, visual information from the eye passes through the thalamic lateral geniculate nuclei, whereas sound information from the ear passes through the thalamic medial geniculate nuclei.
Many nuclei of the thalamus have widespread cortical projections.
Is the cerebral cortex made up of nuclei?
No (except in birds)
What is the cerebral cortex made of?
It is made of a multi-layered structure (typically 6 layers in mammals, 3 layers in reptiles). Neurons are interconnected between layers in a way that gives rise to cortical columns, which are thought to be partially distinct functional units.
What is the cerebral cortex made of?
It is made of a multi-layered structure (typically 6 layers in mammals, 3 layers in reptiles). Neurons are interconnected between layers in a way that gives rise to cortical columns, which are thought to be partially distinct functional units.
What is the largest site of neural integration in the CNS?
The cerebral cortex. It plays a key role in attention, perception, awareness, thought, memory, language, decision making, and consciousness.
The surface of the cerebral hemispheres is the cerebral cortex, which is highly convoluted with _____, _____, and _____.
sulci (small grooves), fissures (large/major grooves), gyri (ridges between sulci or fissures)
These convolutions increase the surface area of the cerebral cortex.
What is the outermost portion of the cerebral cortex called and why do we call it that?
The gray matter. We call it that because of the high concentration of cell bodies there, which makes it gray.
What does the white matter contain and where is it located?
It has a large concentration of myelinated axons. There are very few neurons in this area. It is located beneath the gray matter.
What is the name of the fissure that separates the 2 hemispheres?
The longitudinal fissure
What is the name of the fissure that separates the frontal from the temporal lobe?
The lateral fissure
What structure provides a good landmark separating the rostral and caudal divisions of the cerebral hemispheres?
The central sulcus
What is the corpus callosum and what is its function?
A large band of axons that connects corresponding parts of association cortex of the left and right hemispheres. Although the two cerebral hemispheres perform somewhat different functions, perceptions and memories are unified by the corpus callosum.
What are the 4 lobes of the cerebral cortex?
- The frontal lobe
- The parietal lobe
- The occipital lobe
4.The temporal lobe
What does the frontal lobe control?
Movement
What does the parietal lobe process?
Touch information
What does the occipital lobe process?
Visual information
What does the temporal lobe process?
Auditory information
Where are taste and smell processed?
Near the junction of the frontal, parietal, and temporal lobes inside the lateral fissure.
Taste is processed in the insular cortex. Smell in the piriform cortex.
What does the primary motor cortex in the frontal lobe contain?
The motor neurons that synapse in the spinal cord.
Where does touch information first enter the cerebral cortex?
In the somatosensory cortex in the parietal lobe.
Different regions of the somatosensory cortex receive information from different parts of the body (ex: feet, hands, fingers).
Where does visual information first enter the cerebral cortex?
In the primary visual cortex in the occipital lobe
Where does the auditory information first enter the cerebral cortex?
In the primary auditory cortex in the temporal lobe
Where does gustatory information first enter the cerebral cortex?
In the insular cortex hidden in the lateral fissure
Where do each primary sensory areas of the cortex send information to?
The sensory association cortex
What is it that takes place in the sensory association cortex?
Perception takes place there and memories are stored there.
Regions of the sensory association cortex located closest to the primary sensory areas receive information from only one sensory system
What did the basal ganglia use to be called?
The primitive “reptilian” brain. It is now clear that reptiles and birds have other components of the cerebrum than the basal ganglia.
The basal ganglia and limbic system are often referred to as _____ _____, since they sit beneath the cerebral cortex.
subcortical structures
