The subject is asked to report whether they felt one or two points. The tester alternates using one point and two points on the area being tested (e.g. While a subject's eyes are closed, a folded paperclip can be used to test two-point discrimination, which is mediated by the parietal lobe. Using callipers or a folded paperclip, and asking a subject to keep their eyes closed, this test can be used to check parietal lobe function. Different areas of the body have more sensory receptors, and so are more sensitive than others in discerning distinct points. This process is called two-point discrimination.
Areas in the parietal lobe are responsible for integrating sensory information, including touch, temperature, pressure and pain.īecause of the processing that occurs in the parietal lobe, we are able to, for example, discern from touch alone that two objects touching the skin at nearby points are distinct, rather than one object. The parietal lobe is behind the frontal lobe, separated by the central sulcus. Image: In 1848, Phineas Gage survived an explosion that drove a tamping iron through his left frontal lobe. (Image: Ratiu et al / CC BY-SA 2.1) Parietal lobe After the accident, others noticed changes in Gage’s personality: before the accident, he was known as responsible and hard-working, but afterwards, he became disrespectful, foul-mouthed and had difficulty carrying out plans. The frontal lobe also contains the primary motor cortex, the major region responsible for voluntary movement.
Miraculously, Gage survived, blinded in his left eye and sustaining damage to much of his left frontal lobe. While his head was slightly turned, a mistaken strike sparked an explosion that forced the rod upwards into his left eye and out through his skull. In 1848, Gage was using a tamping iron to pack in gunpowder for blasting a tunnel through rock. The most famous case of frontal lobe dysfunction is the story of railway worker Phineas Gage. This is why in frontotemporal dementia, personality changes are often the first signs of the disease. The frontal lobe is generally where higher executive functions including emotional regulation, planning, reasoning and problem solving occur. The frontal lobe is separated from the parietal lobe by a space called the central sulcus, and from the temporal lobe by the lateral sulcus. Image: (L) DJ / CC BY-SA 2.0 (R) Albert Kok / Public Domain Frontal lobe
The folding of the brain, and the resulting gyri and sulci, increases its surface area and enables more cerebral cortex matter to fit inside the skull. These are known as gyri (bumps) and sulci (groves or fissures). In humans, the lobes of the brain are divided by a number of bumps and grooves. Traditionally, each of the hemispheres has been divided into four lobes: frontal, parietal, temporal and occipital.Īlthough we now know that most brain functions rely on many different regions across the entire brain working in conjunction, it is still true that each lobe carries out the bulk of certain functions. The cerebral cortex is divided lengthways into two cerebral hemispheres connected by the corpus callosum. The brain’s cerebral cortex is the outermost layer that gives the brain its characteristic wrinkly appearance.
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