Regulatory systems

Identification and characterization of a melanin-concentrating hormone receptor.

An, S. et al. Proc. Natl Acad. Sci. USA 98, 7576–7581 (2001) Pubmed

Melanin-concentrating hormone (MCH) is involved in the control of food intake. This paper and three others report the identification of a new MCH receptor that is expressed in hypothalamic areas known to regulate feeding behaviour. The gene for the new receptor is located in a region of chromosome 6 that is associated with cytogenetic abnormalities in obese patients, highlighting its possible involvement in this condition.

Synaptic physiology

Epilepsy, hyperalgesia, impaired memory, and loss of pre- and postsynaptic GABAB responses in mice lacking GABAB(1).

Schuler, V. et al. Neuron 31, 47–58 (2001) [contents page]

The authors generated GABAB(1)-knockout mice and found that the animals showed spontaneous seizures, hyperalgesia, increased motor activity and impaired learning in a passive avoidance task. More importantly, pre- and postsynaptic GABAB-receptor-mediated responses were abolished. As metabotropic receptors in this class require dimerization for their function, the data indicate that GABAB(1) might be an obligatory component of GABAB receptors.

Development

Progressive cerebellar, auditory and esophageal dysfunction caused by targeted disruption of the frizzled-4 gene.

Wang, Y. et al. J. Neurosci. 21, 4761–4771 (2001) Pubmed

Wnt signalling is involved in patterning, cell proliferation and synapse formation in the developing embryo. Wang et al. now report that it might also be important in later life. They deleted frizzled-4, which encodes a Wnt signal transducer. The adult mutant mice showed cerebellar degeneration and loss of auditory neurons, neither of which could be attributed to primary developmental defects. This implies that Wnt signalling is required for maintenance, as well as development, of the nervous system.

learning and memory

A neural correlate of working memory in the monkey primary visual cortex.

Super, H. et al. Science 293, 120–124 (2001) Pubmed

Super et al. recorded from neurons in the primary visual cortex of monkeys during a delayed-response task. In this task, the animals had to remember the position of a stimulus and make a saccade to it after a delay. Neurons that responded to the visual stimulus continued to fire during the delay period, and their activity correlated with subsequent performance. The authors propose that this activity might represent a memory trace of the stimulus.