Memory: Hippocampus, Perirhinal Cortex and Striatum

Memory: Hippocampus, Perirhinal Cortex and Striatum

Song and colleagues (2011) propose nonlinear relationships between activity in the hippocampus and perirhinal cortex during time of encoding and memory strength; and also that the two are dissimilar. The fMRI (functional Magnetic Resonance Imaging) study they conducted supports the statement.

Using the same neuroimaging method, Duncan and others (2011) highlight the importance of hippocampal area CA1 in match/mismatch detection. The way the structure records an event depends on whether what takes place corresponds to expectations. The authors believe that, precisely, the CA1 neurons perform this calculation.

La douleur. Memory plays a role in most aspects of learning, even in skill games and cue sports, such as pool (i.e. two types retention are involves, explicit memory: one must remember the rules, and implicit memory: one needs to know how to hold the cue stick). Young woman on billiards table. Image: Copyright © Megan Jorgensen (Elena)

Clearly, the hippocampus is important for memory. However, the striatum also plays a role. Sadeh and coauthors (2011) explain how cooperation between the two regions ensues during episodic encoding. Continuing with BOLD (Blood Oxygen Level Dependent) signals methodology, the group was able to demonstrate that successful information recording was linked to higher activity in both: the hippocampus and the striatum (putamen).

Hypothalamus & Food

The major inhibitory neurotransmitter GABA (γ-Aminobutyric acid or Gamma-AminoButyricAcid) is often associated with energy regulation and eating. So is the hypothalamus, located at the base of the brain. For instance, hypophagia and resultant weight loss caused by cobalt protoporphyrin in mice, is related to diminished activity of nitric oxide synthase in that part of the brain (Li et al. , 2006). Further, the link (via the pituitary gland) between the endocrine and nervous systems is also hypothalamic in nature.

Moreover, Williams & Elmquist (2011) write that the optogenetic placement of nutrition intake related actions, corresponds to the arcuate nucleus of the hypothalamus. More precisely, the pro-opiomelanocortin (POMC) and agouti-related peptide (AGRP) neurons would be responsible for this regulating mechanism. Furthermore, the roles played by the two cell types appear contradictory. POMC activity decreases food intake, while AGRP elevates it.

Along these lines, leptin orOBprotein expression in the hypothalamus, has also been said to reduce appetite in rats (Schwartz et al., 1996). Clearly, the structure is crucial for metabolism.

Intelligence – Neural Correlates

Intelligence is a significantly broad topic, and can thus be approached from different angles. On the one hand, Lefebvre (2011) maintains that innovation constitutes an ecological measure of intelligence in the wild. Along these lines, behavioral flexibility would allow animals to cope with their environments. However, the author also proposes that cognition should be viewed in general terms, rather than in modular, despite some components definitely being domain-specific. Interestingly, tool use may correlate with brain size. For example the New Caledonian crow, the non-human most apt at using tools, has a proportionately larger brain than its avian close relatives.

On the other hand, Geake (2011) centers on educational neuroscience and proclaims, “our brains did not evolve to go to school” (44). Interestingly, the researcher suggests that analogy making is central to acumen. Although the author introduces a distinction, since in creative thinking, fluid analogizing takes center stage. Therefore, more than one right answer is possible. Further, the experimenter found a correlation between the process and verbal IQ. IQ scores, despite being disputed as an absolute representation of sharpness, are a good predictor of academic performance. Again, the writer stresses that several brain areas are involved in higher cognitive processes, even though the frontal and parietal lobes have consistently been implicated. Further, Brodmann areas have similarly been indicated in the literature as candidates for explaining differences in astuteness between persons (Deary et al., 2010).

Finally, one must also keep in mind that the capability may be subdivided into several components, such as vocabulary, processing speed, memory, spatial ability and reasoning. However, general intelligence or ‘g’, means that those who perform well in one domain usually perform well across the board. Such a situation renders difficult defining neural correlates of intelligence, since even on domain specific tasks, level of g is important; g may compensate for any lack of ability – consequently – it’s hard to separate the parts from the whole.

To conclude, the idea that intelligence is highly heritable (genetically programmed) started with Galton’s paper in the 19th century. Also, national IQs have risen over time, at least in Western societies in the 20th century, a phenomenon dubbed the Flynn effect. Lastly, another significant theory on the topic (Multiple Intelligences) comes from Gardner, but lies outside the scope of the present short essay.

References:

• Duncan, K., Ketz, N., Inati, S. J. & Davachi, L. (2011). Evidence for area CA1 as a match/mismatch detector: A high-resolution fMRI study of the human hippocampus. Hippocampus, 00 (0): 1-10.
• Sadeh, T., Shohamy, D., Levy, D. R., Reggev, N.& Maril, A. (2011). Cooperation between the hippocampus and the striatum during episodic encoding. Journal of Cognitive Neuroscience, X (Y): 1-12.
• Song, Z., Wixted, J. T., Smith, C. N. & Squire, L. R. (2011). Different nonlinear functions in hippocampus and perirhinal cortex relating functional MRI activity to memory strength. Proceedings of the National Academy of Science (PNAS): Neuroscience, Early Edition:1-6.

Copyright © 2011 Megan Jorgensen. All Rights Reserved.