Brainy Behavior

I posted a video of my brain on YouTube just to show the quality of MRI scans we have now (and the fun things we can do with post-processing). The scans were done on a 3T Philips Achieva MR scanner. We acquired 2 T1 scans of my brain (160 1mm slices – 1 mm cubed voxel size) then post-processed the DICOMs using FreeSurfer. The skull-stripped output files (in NIFTI format) were then rendered in 3D in OsiriX. I created a fly-through movie of the brain and exported it as an MP4 movie. If you have any questions about the process, feel free to ask.

Here is the video PBS recently made about Parkinson’s disease called My Father, My Brother, and Me. From what I’ve watched so far, it’s done a good job putting a face to Parkinson’s disease while also focusing on the research and clinical aspects of it.

Archeologists discovered what may be the oldest human brain. The brain matter is within a skull and is fossilized, or in a similar state. Researchers estimate that the brain dates to around 300 BC. Here’s the link to the BBC story.

On Tuesday, December 2, 2008, Henry M., the most famous patient in modern neuroscience research and literature, passed away. He was 82. In 1953, H.M. had an experimental brain operation to try to stop his frequent seizures; his medial temporal lobes were resected bilaterally, with significant portions of his amygdalas and hippocampi in both cerebral hemispheres removed (parts of the brain are still resected in intractable epilepsy cases, however neurosurgeons do not perform that exact surgery any more because of the negative effects). His seizures stopped but immediately after the operation he had a severe anterograde amnesia. This means that from when he received the operation at age 27, he was unable to establish new memories for world events and for general information.

His amnesia became the focus of much scientific study from after his operation until the present. No one patient has been studied more in the 20th and 21st centuries than H.M. His memory impairment was also interesting because his overall intellectual abilities were still intact as was his personality. Neuropsychologists and neuroscientists will forever be grateful for the things they learned from H.M.

The New York Times has a very nice article about H.M.

Clive Wearing is a 70 year old British man who contracted herpes simplex encephalitis in 1985. The virus destroyed his hippocampi bilaterally (as well as surrounding areas). He has complete anterograde amnesia and can only remember up to about 20 seconds. He retained the ability to play the piano and conduct a choir (which he did previously to his illness); this is because this procedural memory involves different areas of the brain, including the basal ganglia and the cerebellum. I’ll revisit this case over the coming days. Meanwhile, here is a clip from a BBC production that presents part of Clive’s story.

To follow up my previous post on the hippocampus, here’s a video posted by drbobrd on YouTube. He uses a model of a brain to explain some brain anatomy, including the hippocampus and fornix.

I have to apologize for the paucity of posts on this blog. The grind of my semester got to me. After a few week break it’s time for a neuroanatomy post.

WIthin the temporal lobe of the brain is an elongated structure called the hippocampus. Some people have compared its shape to that of a seahorse (the word hippocampus comes from the Greek {hippos + campos}, which roughly means “seahorse”). This structure is special for a number of reasons. One is its role in memory encoding and consolidation.

From cytoarchitectonic standpoint, the hippocampus is special because unlike the surrounding cortex, it consists of only three layers instead of six. The hippocampus is phylogenetically an old part of the cortex, which means that it is an older branch on the evolutionary tree, whereas the rest of the cortex (more accurately called the neocortex), especially cortex of the frontal lobes, is a much newer development.

The hippocampus (to be more accurate, there are two hippocampi – one in each cerebral hemisphere) resides within the medial portion of the temporal lobe. It is continuous with the parahippocampal cortex, entorhinal cortex (the hippocampus receives its main input from this cortex), and perirhinal cortex. I’ll not write about the internal structure of the hippocampus, which becomes fairly complex, due to the brief nature of this post.

The hippocampus sends white matter tracts off its dorsal and posterior portions (the hippocampus also communicates through other tracts and pathways – this circuit is not the only output of the hippocampus). These white matter tracts are the fimbria of the hippocampus (technically, the fimbria are the “offshoots” of the alveus of the hippocampus). The fimbria proceeds upwards from the posterior portion of the hippocampus, at which point it ceases to be the fimbria and is called the fornix.

The fornices (plural of fornix) are prominent white matter tracts passing above the thalamus and medially in the brain. The fibers travel forward, then turn downward just posterior to the anterior commissure (a white matter tract that connects both hemispheres) to terminate in the mammillary bodies, two bumps on the ventral side of the brain. They are part of the hypothalamus of the brain. From there, the pathway courses upward through the mammilothalamic tract (MTT) to the anterior nucleus of the thalamus. From there axons course to the cingulate gyrus, then to the underlying cingulum (large white matter tract), and back to the hippocampus (via the parahippocampal and entorhinal cortices). This circuit is part of the limbic system and is called the Papez (pronounced “papes” – rhymes with capes) circuit. This circuit is important for emotion (and memory).

I have a new post up on BrainBlogger about Alien Limb Syndrome. Here’s the link.

I’m quite fascinated by human anatomy, especially neuroanatomy. The human body is amazing; it’s something of a miracle that it develops and works as well and as often as it does. The brain is very complex with up to 100 million neurons (that’s also an estimate of the number of stars in our galaxy) and 100 trillion synapses (connections between neurons)! 100 trillion is an estimate of how many individual cells the entire human body has. We have as many synapses as cells in the entire body. The brain is complex and beautiful. It has symmetry but individuality.

I discovered a website that allows you to watch some surgeries live (or to view archives of past surgeries). OR-Live.com is informational and free. For those interested in neurosurgeries – everything from scoliosis surgery to tumor resection to deep brain stimulation – here is the direct link. Most of the videos are available in Flash format for web-viewing. Many are also available to download as a video podcast. Warning – please don’t watch the videos if you get queasy easily; if you feel queasy while watching one, take a break and do something else for a while.

I hope my readers enjoy this site as much as I have in the past and will continue to in the future.

Mo at Neurophilosophy posted a great video of Deep Brain Stimulation (DBS) surgery being performed on a man with essential tremor, while he plays the banjo. As with most brain surgeries, the patient was awake, alert, and talking. The doctors had him play the banjo so they could fine tune (pun intended) the electrode placement in order to have the best response.