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Evan Balaban

Publications and source records attributed to Evan Balaban.

10 recordsLinked to original sources
PubMed2006

Getting into shape: optimal ligand gradients for axonal guidance.

During neural development, neurons from downstream, presynaptic regions of the nervous system (such as the retina) send spatially patterned axonal projections to upstream, target regions (the tectum or superior colliculus). A servomechanism model has been proposed to explain the pattern and time-course of axonal growth between these two regions [Honda, H., 1998. Topographic mapping in the retinotectal projection by means of complementary ligand and receptor gradients: a computer simulation study. J. Theor. Biol., 192, 235-246]. Here, we show that a modification of this model incorporating a different criterion for axonal decision-making, called the local optimum rule, is guaranteed to converge to a topographic map under a wide range of conditions encountered during neural development. A theoretical investigation of these conditions leads to new hypotheses regarding map formation.

Animals↗
PubMed2006

Cognitive developmental biology: history, process and fortune's wheel.

Biological contributions to cognitive development continue to be conceived predominantly along deterministic lines, with proponents of different positions arguing about the preponderance of gene-based versus experience-based influences that organize brain circuits irreversibly during prenatal or early postnatal life, and evolutionary influences acting through selection on small numbers of genes. This article discusses evolutionary, mechanistic and probabilistic aspects of developmental processes that cognitive scientists need to better integrate. Developmental processes inseparably fuse experience-dependent and experience-independent components, have important stochastic contributions, and exhibit a greater degree of mechanistic continuity between developing and adult nervous systems than previously thought. Their balanced integration leads to new models for "critical or sensitive" period phenomena and behavioral biases. A general understanding of behavioral development - cognitive developmental biology--will require better coordination between comparative animal and human developmental research programs.

Brain↗
PubMed2005

Brain switching: studying evolutionary behavioral changes in the context of individual brain development.

Working together at Nogent, Marie-Aimee Teillet, Nicole Le Douarin and the author successfully developed an extension of the quail-chick transplant technique for relating species brain cell differences to behavioral differences. This article reviews the application of the technique to species differences in motor behavior (crowing) and auditory perceptual preferences. Interspecies brain transplants provide a unique means for elucidating general cellular mechanisms which integrate evolutionary and individual experience during the development of complex brain circuitry.

Animals↗
PubMed2004

Human auditory cortical dynamics during perception of long acoustic sequences: phase tracking of carrier frequency by the auditory steady-state response.

We recorded human auditory cortical activity during the perception of long, changing acoustic signals and analyzed information provided by dynamic neural population measures over a large range of time intervals (approximately 24 ms-5 s). Participants listened to musical scales that were amplitude modulated at a rate of 41.5 Hz, generating an ongoing, stimulus-related oscillatory brain signal, the auditory steady-state response (aSSR). The aSSR generated energy at the amplitude modulation rate that was recorded using magnetoencephalography. As in previous work, the timing (phase) of this response varied with stimulus carrier frequency over the entire course of minute-long tone sequences ('phase tracking' of carrier frequency). The length of the time interval over which phase was calculated was systematically varied; significant phase tracking was regularly observed at analysis intervals of <50 ms in length. The right auditory cortex exhibited better phase tracking performance than the left at analysis intervals of 24-240 ms, and frequency dependent phase delays were consistently larger than those predicted by cochlear mechanics. Based on these empirical data, a model of the neural populations responsible for phase tracking suggests that it is produced by a subpopulation ( approximately 25%) of the cells generating the aSSR.

Acoustic Stimulation↗
PubMed2003

Fos and FRA protein expression in rat precerebellar structures during the Neurolab Space Mission.

Changes in gene expression were examined in precerebellar structures during and after space flight. These structures included the inferior olive (IO), the source of climbing fibers, and the lateral reticular nucleus (LRt) and basilar pontine nuclei (PN), sources of mossy fibers. We examined two immediate early gene products with two different time courses of expression: Fos, which persists only for a few (6-8)h after activation and FRA expression, which lasts for longer periods of time, i.e. hours and/or days after activation. Gravity effects on Fos and FRA gene expression were evident in vestibular and visual areas of the IO, including the dorsomedial cell column, the beta subnucleus and the dorsal cap of Kooy of the medial nucleus (which projects to the flocculonodular lobe, i.e. to the vestibular area of the IO involved in the olivary control of the vestibulo-ocular reflex (VOR)). Gene expression also affected the subnuclei A, B, and C and the caudal part of the medial IO. These olivary regions do not receive vestibular afferents, but rather spinal afferents, and are particularly involved in the olivary control of the vestibulospinal reflex (VSR). Changes in Fos expression were also observed in the LRt and the PN. We suggest that sensory substitution, in which signals produced by a subject's own activity replace activity normally provided by macular stimulation, contributes to the recovery of microgravity-related postural and motor deficits. While no consistent increases in FRA expression occurred in vestibular IO regions 24h after launch, consistent increases in FRA expression occurred 24h after landing. We hypothesize that this asymmetrical pattern of gene expression resulted from (i). tonic microgravity experienced after launch counteracting the effects of increased phasic gravitational forces experienced during launch, and (ii). the tonic gravitational field experienced after landing potentiating the effects of increased phasic gravitational forces experienced during landing. The specificity of these results is demonstrated by an absence of direct gravity-related changes in Fos expression in other precerebellar structures such as the external cuneate nucleus, group X, and the dorsal column nuclei that transmit exteroceptive and proprioceptive signals to thalamic nuclei and somatosensory areas of the cerebral cortex. The gravity-related Fos and FRA expression changes in the IO and the LRt seen here are of interest in view of the important role their projections play in adaptive gain changes of the VOR and VSR during sustained visuo-vestibular and neck-vestibular stimulation.

Animals↗
PubMed2002

Fos and FRA protein expression in rat nucleus paragigantocellularis lateralis during different space flight conditions.

The nucleus paragigantocellularis lateralis (LPGi) exerts a prominent excitatory influence over locus coeruleus (LC) neurons, which respond to gravity signals. We investigated whether adult albino rats exposed to different gravitational fields during the NASA Neurolab Mission (STS-90) showed changes in Fos and Fos-related antigen (FRA) protein expression in the LPGi and related cardiovascular, vasomotor, and respiratory areas. Fos and FRA proteins are induced rapidly by external stimuli and return to basal levels within hours (Fos) or days (FRA) after stimulation. Exposure to a light pulse (LP) 1 h prior to sacrifice led to increased Fos expression in subjects maintained for 2 weeks in constant gravity (either at approximately 0 or 1 G). Within 24 h of a gravitational change (launch or landing), the Fos response to LP was abolished. A significant Fos response was also induced by gravitational stimuli during landing, but not during launch. FRA responses to LP showed a mirror image pattern, with significant responses 24 h after launch and landing, but no responses after 2 weeks at approximately 0 or 1 G. There were no direct FRA responses to gravity changes. The juxtafacial and retrofacial parts of the LPGi, which integrate somatosensory/acoustic and autonomic signals, respectively, also showed gravity-related increases in LP-induced FRA expression 24 h after launch and landing. The neighboring nucleus ambiguus (Amb) showed completely different patterns of Fos and FRA expression, demonstrating the anatomical specificity of these results. Immediate early gene expression in the LPGi and related cardiovascular vasomotor and ventral respiratory areas may be directly regulated by excitatory afferents from vestibular gravity receptors. These structures could play an important role in shaping cardiovascular and respiratory function during adaptation to altered gravitational environments encountered during space flight and after return to earth.

Animals↗
PubMed2002

Auditory stimulus-induced changes in immediate-early gene expression related to an inborn perceptual predisposition.

Auditory-induced expression of the immediate-early gene ZENK was examined in 18 brain areas of domestic chicken and Japanese quail subjects with no previous exposure to parental vocalizations. After one 30-min exposure (approximately 120 calls) within 24 h of hatching to either the chicken or quail maternal call, paired subjects from each species showed significantly more intense levels of ZENK staining to conspecific (own species) calls. Single brain areas did not show consistent, large differences in ZENK expression across all subject pairs. Instead, a majority of brain areas exhibited a small conspecific stimulus-induced staining advantage in each species. The species differed in the quantitative distribution of ZENK responses among brain areas; qualitative patterns of call-induced staining exhibited both similarities and differences. The results suggest shared neural correlates and potential developmental/evolutionary differences in congenital brain responses to biologically significant auditory stimuli in naïve individuals of the two species.

Acoustic Stimulation↗
PubMed2002

Tonic gravity changes alter gene expression in the efferent vestibular nucleus.

To assess effects of tonic gravity changes on efferent vestibular neurons, immediate early gene (IEG) protein expression was compared in the efferent vestibular nucleus (EVe) of adult rats exposed to microgravity during the NASA Neurolab Mission (STS-90), and matching control animals on the ground. Rats sacrificed 1 day and 12 days after launch (experiencing approximately 0g) showed significantly fewer IEG protein-expressing cells than corresponding ground control animals (at 1 g). Normal IEG protein-expressing cell numbers reappeared within I day after flight animals returned to earth, and were maintained at 14 days after landing. EVe neurons appear to play a role in gravity-induced modifications of vestibular hair cell synapses; a contribution to gravity-induced plasticity of the vestibulo-ocular reflex (VOR) is also suggested.

Animals↗