The Brain and its development Flashcards

Question

Division of cells

Answer 1

original cells in the ventricular zone are called progenitor cells and these undergo symmetrical division producing simialr cells At 7 weeks asymmetrical division occurs producing 1 progenitor and 1 brain cell First brain cell is radial glial cells with long extensions Next C-R cells and finally neurones are formed Asymmetrical division goes on for 3 months after which the progenitor cells die - apoptosis)

Answer 2

Somal translocation - like a lava lamp. Extensions come from the top and cell body moves after with bottom retracting - Ridley et al., 2003 Gila mediated migration - climbing rope. Follows the extensions from radial glial cells (Campbell and Gotz, 2002) Human cerebral cortex has at least 100 billion neurones. Shortest migration takes a day, longest 5 weeks. Once I I position they form dendrites and axons, connecting with other neurones. Cells forming neural crest go on to form the peripheral nervous system and migrate long distances tangentally

Answer 3

krubitzer (1998) removed area of cortex of an opossum which normally formed visual cortex. Visual cortex later developed in a different place and caused other areas, audio and somatosensory to be smaller Specialisation can be due to axon connections into area Axons from thalamus spread into cortex and control development of cells in the cortex. If the axons are cut then development of the cells is stopped Rely on external stimuli Visual stimuli required to generate area of occipital lobe which co-ordinates stereopsis is an example of how external stimulation can control cell development

Answer 4

50% more neurons produced than survive Active process apoptosis were contents of the cell is neatly packaged and macroglia attracted to remove If apoptosis blocked can cause cancer, if triggered inappropriately results in neurogenerative disease Incorrect connections likely to die, leading to increase in selectivity of transmission between cells

Answer 5

volume of the brain quadruples between birth and adulthood (Johnson, 2001) Due to increased dendritic branching, synaptic sis and myelination Not all increasing Reduction in synapse density in visual cortex over first 3 years but in prefrontal cortex adult levels out at 14 years Grey matter grows large in childhood then decreases in adulthood - Amso & Casey, 2005

Answer 6

Taxi drivers have a bigger posterior hippocampus than controls

Answer 7

longitudinal study to test cause and effect Positive correlation correlation between time in taxi and posterior hippocampus Volume change of anterior hippocampus - negative correlation

Answer 8

Studied taxi drivers and bus drivers. Only taxi drivers had larger posterior hippocampus than controls

Answer 9

Knudsen and brainard (1991) placing glasses on owls which altered view resulted in auditory field also changing Enhanced environments result in thickened cortex (Greenough, 1975) Juggling increases cortex (draganski et al., 2004) Brain volume decreases less in people who stay mentally active (Schooler, 2007) Munte, Altenmuller & Janke (2002) exposure to music training changes auditory cortex in humans, a musician with perfect pitch has a larger left plenum temporale String musicians were found to have larger motor cortical maps of the hand on the right cortex. They are required to hold down strings with left hand - Elbert et al., 1995 Being aware of stimulation matters (Braun et al., 2000) 2 groups had stimulation to finger and thumb. Group 1 passive exposure and group 2 active exposure - they were asked to identify which digit was stimulated only group 2 saw increase in size of map of finger on cortex

Answer 10

in adulthood we can gain new neurones 2 areas of neurogenesis Olfactory bulb Hippocampus (area involved with learning)

Answer 11

they have lower activation and plasticity threshold leading to preferential recruitment of these cells into functional circuits (Kee et al., 2007) Survival of new neurones - over first month over 50% die Creation of new cells (neurogenesis) is positively affected by enriched environments or behavioural tasks such as spatial learning (Gould et al. 1999) Reduced neurogenesis leads to poor spatial learning (Barkas et al. (2012)

Answer 12

intact somatosensory system: Original cortical area responding to touches at area B. Original cortical area responding to touches at A. Two days after damage to nerve B Area released from inhibition repsonds to touches at A. Original area responding to touches at A. Six months after damage to nerve B. Area into which sprouting has occurred responds to touches at A. Area released from inhibition responds to touches at A. Original area responding to touches at A

Answer 13

Pons et al (1990) found monkey with severed sensory neurons to their arms had reorganised somatosensory cortex. The face area had expanded into what had previously received inputs from the arm.

Answer 14

Ramachandran & Blakeslee, 1998 Reported the case of Tom who had a phantom limb. When Tom’s face on the same side as his amputated arm was touched he reported feeling sensations from various parts of his phantom hand